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HUMAN ANATOMY
MORRIS


ARRANGEMENT
OF
SUBJECTS AND AUTHORS.
OSTEOLOGY. By J. Bland Sutton, F.R.C.S., Lecturer on Compara-
tive Anatomy, and Senior Demonstrator of Anatomy, Middlesex Hospital;
Hunterian Professor Royal College of Surgeons, etc.
JOINTS. By the Editor, Henry Morris, F.R.C.S., Surgeon to, and
Lecturer on Surgery at, Middlesex Hospital; Examiner on Anatomy in
Royal College of Physicians and Royal College of Surgeons, etc.
MUSCLES. By J. H. Davies-Colley, F.R.C.S., Mem. Path. and Clin.
Soc., London; Fellow Medico Chir. Soc.; Surgeon to, and Lecturer on
Surgery (late Lecturer on Anatomy), Guy's Hospital, etc.
BLOOD-VESSELS AND LYMPHATICS. By Wm. J. Walsham,
F.R.C.S., Author of "Manual of Practical Surgery," Assistant Surgeon
to, and Lecturer on Anatomy at, St. Bartholomew's Hospital, etc.
NERVOUS SYSTEM. By H. St. John Brooks, M.D., of Dublin,
Secretary for Ireland of Anat. Soc. of Great Britain; Chief Demon-
strator of Anatomy University of Dublin, etc.
EYE. By R. Marcus Gunn, F.R.C.S., Mem. Path., Ophthal., and
Neurol. Soc.; Surgeon to Royal London and to the Western Ophthal-
mological Hospitals, etc.
TONGUE, NOSE, EAR, HEART, VOICE, RESPIRATION.
By Arthur Hensman, F.R.C.S., Aural Surgeon (late Senior Demonstrator
of Anatomy) Middlesex Hospital, Lecturer on Aural Surgery and
Anatomy Middlesex Hospital Medical School.
ORGANS OF DIGESTION. By Frederick Treves, F.R.C.S., Sur-
geon and Lecturer on Anatomy London Hospital, etc.
URINARY AND GENERATIVE ORGANS. By William Ander-
son, F.R.C.S., Assistant Surgeon, Lecturer on Anatomy, and Surgeon to
Skin Department St. Thomas' Hospital, Professor of Surgery and Path-
ology Royal College Surgeons, etc.
SURGICAL AND TOPOGRAPHICAL ANATOMY. By W. H.
A. Jacobson, F.R.C.S., Assistant Surgeon to Guy's Hospital, Surgeon to
Royal Hospital for Children and Women, Lecturer on Anatomy (late
Teacher of Operative Surgery) Guy's Hospital Medical School. Author
of "The Operations of Surgery," etc.
PUBLISHERS' NOTICE.
The Illustrations in this book have all
from drawings made by special artists.
been cut on wood
They are mostly
from original sources; those that are not have been duly
credited; all, however, owing to re-drawing and engraving,
are protected by copyright.

HUMAN ANATOMY
A COMPLETE SYSTEMATIC TREATISE
BY VARIOUS AUTHORS
INCLUDING A SPECIAL SECTION ON SURGICAL AND
TOPOGRAPHICAL ANATOMY
Sir
EDITED BY
HENRY MORRIS, M.A. AND M.B. LOND.
SURGEON TO, AND LECTURER ON SURGERY, FORMERLY LECTURER ON ANATOMY, AT THE
MIDDLESEX HOSPITAL, LATE EXAMINER IN ANATOMY IN THE UNIVERSITY
OF DURHAM, AND FOR THE ROYAL COLLEGE OF
PHYSICIANS ON THE CONJOINT BOARD
ILLUSTRATED
BY SEVEN HUNDRED AND NINETY-ONE WOODCUTS
214 OF WHICH ARE PRINTED IN COLORS
FROM DRAWINGS MADE EXPRESSLY FOR THIS WORK BY SPECIAL ARTISTS

PHILADELPHIA
P. BLAKISTON, SON & CO.
IOI2 WALNUT STREET
1895
Medical Library
QM
23
.M88
1895
COPYRIGHT, 1893, BY P. BLAKISTON, SON & Co.
PRESS OF WM. F. FELL & CO.,
1220-24 SANSOM ST.,
PHILADELPHIA.
11-30-59
Medical
08121-59
gift

EDITOR'S PREFACE
THIS Treatise on Human Anatomy is designed for the use of Students
preparing for the Conjoint Board of the Royal Colleges of Physicians and
Surgeons, for the Fellowship of the Royal College of Surgeons, and for the
Examinations in Anatomy at the various Universities.
It aims at being a complete and systematic description of every part
and organ of the human body so far as it is studied in the dissecting room.
Histology and development-except the mode and dates of development
of the bones, and in a few other instances are not included, as it is felt that
these subjects are more appropriately dealt with in books on Physiology
than they can conveniently be in works on Anatomy.
The different sections have been written by separate Authors who are
known to have devoted special attention to the subjects allotted to them.
To these gentlemen my best thanks are due for their generous assistance
and able co-operation.
Whilst each Author is alone responsible for the subject-matter of the
article which follows his name, the proof-sheets of other articles besides his
own have in certain cases been submitted to him, so that several of the
articles may be considered to have received the approval and endorsement
of two, three, or more Authors. This has been particularly the case with
the sections on Osteology, Arthrology, Myology, and Neurology. There is,
therefore, reason to believe that such important points as the attachments
of ligaments and of muscles, and the nerve-supply of muscles, etc., will be
found to be in perfect accord in the various sections in which they are
referred to or described.
In the illustrations of the bones, the origins of muscles are indicated by
red lines, the insertions by blue lines, and the attachments of ligaments
by dotted black lines.
A feature of the work which, it is confidently hoped, will facilitate the
work of students, is the mode of describing the illustrations.
vi
PREFACE
This plan was decided upon at a conference of all the Authors and one
of the artists. It consists in printing the descriptions in different types at
the end of the pointers. Thus it will be found that muscles, fasciæ, and
ligaments are in one kind of type; arteries, veins, and lymphatics in another;
bones in a third; and nerve-structures in a fourth. The names of special
organs-such as the liver, lungs, etc.-are printed in the same type as the
bones, so as to avoid too great a variety of lettering.
Several of the illustrations are repeated in different parts of the book,
with the object of sparing the reader the trouble of referring from one
section to another when reference is made in the letterpress to such figures.
As much uniformity as possible has been observed in the size and gen-
eral style of the drawings; but exceptions will be found in the section on
Surgical and Topographical Anatomy, for which many of the illustrations
have been borrowed from another work published by Messrs. J. and A.
Churchill, namely, Bellamy's Surgical Anatomy.'
6
I have to acknowledge with grateful thanks the assistance I have
received from Mr. GORDON BRODIE, who made several dissections from which
drawings were taken; from Mr. J. BLAND SUTTON and Mr. FRANK STEELE
in reading over proof-sheets; from Mr. BURGHARD for the care with which
he has drawn up the Index and Tables of Contents; and from all the artists
named on the title-page.
Mr. BERJEAU and Mr. BALCOMB have drawn a very large proportion of the
figures; and, with Mr. SMIT and Mr. PARKER, have shown a degree of
interest in, and given an amount of time and trouble to the illustrations
for which they merit the fullest recognition.
The beautiful anatomical dissections in the Hunterian Museum which
have been, by permission, copied for this Treatise, are from the hand of
Mr. WILLIAM PEARSON, to whose great skill in dissecting I have much
pleasure in referring.
Too much praise cannot be given to all engaged in the actual printing
of the book for the painstaking care they have devoted to it; especially to
the difficult and precise work of properly registering' and printing the
coloured illustrations.
6
I need only say, in conclusion, that I shall not consider my prolonged
and laborious task has been in vain if it be found that the Treatise
adequately meets the requirements of Students, for whom it is written.
HENRY MORRIS.
8 CAVENDISH SQUARE: January 1893.
ALPHABETICAL LIST OF CONTRIBUTORS
WILLIAM ANDERSON
H. ST. JOHN BROOKS
J. N. C. DAVIES-COLLEY
R. MARCUS GUNN
ARTHUR HENSMAN
W. H. A. JACOBSON
HENRY MORRIS

J. BLAND SUTTON
FREDERICK TREVES
W. J. WALSHAM
Page 11, fig. 11, for Splenius capitis
دو
27,
55
109,
دو
وو
39
29
59
دو
99
Scalenus medius
(origin)
ERRATA
Splenius colli
read Scalenus medius
(insertion)
30, for Sterno-mastoid read MIDDLE NUCHAL LINE For MIDDLE NUCHAL LINE read Sterno-mastoid
113, insertion of the Serratus posticus superior should be blue, not red.
114, opposite the twelfth rib, for FCAET read FACET
132. 132, for External lateral ligament read Internal lateral ligament
دو
وو
figs. 132 and 133, at the lower end of the bone substitute Anterior and Posterior radio-carpal ligament for
Capsular ligament and Capsule respectively
165 and 166, figs. 165 and 166, substitute Coronary for Capsule at the head of the tibia. At the lower end, sub-
stitute Anterior and Posterior ligament of ankle joint for Capsule
255, line 12, for THE INTERCARPAL ARTICULATIONS read THE INTERMETACARPAL ARTICULA-
TIONS
,, 293,
", 300,
23
وو
59
30, for The metacarpo-phalangeal joint of the great toe read The metatarso-phalangeal joint of the
great toe
14, after elbow, should be inserted: it therefore forms a lever of the second order.'
355, fig. 280, for Anterior annular ligament read Deep fascia of forearm
,,452, 4 lines from foot, for inframaxillary read inframandibular
وو
22
66
33
99
35
35
39
59
35
35
41
66
465, last line but one,
467, 5 lines from foot, for supramaxillary read supramandibular
468, line 16,
469, lines 17 and 18,
470, line 6,
471,
472,
99
14,
28,
for inferior maxillary nerve read mandibular or third division of the fifth nerve
478, lines 14 and 15 from foot, for inferior dental branch of the inferior maxillary read mandibular nerve
480, line 11, for inferior dental read mandibular nerve
489, "
13, for thyroidea read thyroideæ
59
55
14, for arteria septum narium read arteria septi nasi
518, 7, for inferior dental read mandibular nerve
99
548, 32, for external intercostal membrane read anterior (or external) intercostal membrane
دو
578, fig. 360, The commencement of the left common carotid, and left subclavian arteries should have been
" 584,
دو
66
35
29
601,
coloured red.
,, 363, The cystic artery has been omitted on the red block: its position on the gall bladder is, however,
indicated.
59
615, "
623,
670,
29
65
دو
95
368, There is an accidental red coloured blot at the end of the pointer of Iliacus muscle. This error
372, is corrected on page 1216, where the figure is repeated.
375, The long or internal saphenous nerve is inadvertently coloured blue where seen above the insertion
of the Adductor magnus. This error is corrected in the repetition of the figure on page 1226.
391, The cystic artery has been omitted on the red block: its position on the gall bladder is, however,
indicated.
725, line 4, for external orbital gyrus read posterior orbital gyrus
3 from foot, omit in
99
779,
99
22
782,
23
33
66
25
دو
دو
omit and
818, last line, for pharynx read larynx
821, line 14, for concavity read convexity
837,
دو
1, for posterior cord read outer cord
849,
55
4 from foot, for hip joint read knee joint
29
867, headline, for GANGLIONS read GANGLIA
891, fig. 482, In right upper corner of this figure the lachrymal artery is printed without its red colour.
39
دو
956, line 2, for thyroid body read thymus gland
8, for thyroid gland read thymus gland
وو
965 and 973, figs. 547 and 554, The red and blue valves are not accurately registered; the blue are slightly too
low; the red both too low and too much to the right of the reader.
27
وو
981, line 25, for enervated read innervated
,, 1064,
10, for one-sixteenth read one-sixtieth
NOTE.-The nerve-supply of the Lumbrical muscles of the foot, and of the External Oblique muscles of the abdo-
men, is somewhat differently given in the two sections. See respectively pages 405 and 863; and pages 430 and 845.

CONTENTS
SECTION I
OSTEOLOGY
BY J. BLAND SUTTON

PAGE
PAGE
The Skeleton
A Classified List of the Bones to
show their Mode of Develop-
ment
The Spine.
Characters of a Typical Verte-
bra.
The Cervical Vertebræ
The Thoracic or Dorsal Vertebræ
The Lumbar Vertebræ
The Sacral and Coccygeal Verte-
bræ
The Spinal Column in general
Ossification of the Vertebræ .
Serial Morphology of the Verte-
bræ
The Bones of the Skull
The Appendicular Elements of the
Skull
Mandible (Lower Jaw).
Hyoid Bone
•
1
25
6
7-11
12
.15-18
EA 38 882
.26-68
Styloid Process
Ear Bones
The Skull as a whole-
Exterior of the Skull
The Orbits
The Nasal Fossæ
Interior of the Skull
The Teeth
Morphology of the Skull
Metamorphosis of the Branchial
Bars
Skull at Birth
Peculiarities of Individual Bones
at Birth.
Nerve-Foramina of the Skull.
•
73
73-75
578 89 9டிஐஐன
97
86
88
100
105
The Ribs and Sternum
106
The Thorax.
117
The Bones of the Upper Extremity 118-148
The Hip-Bone
148
.
155
The Bones of the Lower Extremity 156-185
The Pelvis.
SECTION II
THE ARTICULATIONS
BY HENRY MORRIS
Structures entering into the formation
of Joints
186
The Articulation of the Atlas
with the Occiput.
193
•
The various kinds of Articulations
187
The Articulations between
The various Movements of Joints
188
the Atlas and Axis .
196
The Articulations of the Skull
189
The Temporo-mandibular Articu-
lation
The Ligaments uniting the
Occiput and Axis.
198
.
189
The Articulations of the Trunk.
200
The
Ligaments and
Joints
The Articulations of the Vertebral
between the Skull and Spinal
Column
201
Column, and between the Atias
The Articulations of the Bodies
and Axis
193
of the Vertebræ
201
X
CONTENTS
PAGE
PAGE
The Ligaments uniting the
Articular Processes
205
The Ligaments uniting the
Laminæ .
205
The Ligaments uniting the
Spinous Processes
206
•
The Ligaments uniting the
Transverse Processes
207
The Intermetacarpal Articulations 255
The Union of the Heads of the
Metacarpal Bones .
. 255
The Metacarpo-phalangeal Joints . 256
The Metacarpo-phalangeal Joints
of the Four Inner Fingers . . 256
The Metacarpo-phalangeal Joint

of the Thumb
257
209
211
214
The Inter-coccygeal Joints
216
The Articulations of the Pelvis with
the Spine
The Articulations of the Pelvis..
The Sacro-iliac Synchondrosis
and Sacro-sciatic Ligaments 211
The Sacro-coccygeal Articula-
tion
The Tibio-fibular Union.
The Superior Tibio-fibular Joint
The Middle Tibio-fibular Union
The Inferior Tibio-fibular Articu-
The Interphalangeal Articulations
The Articulations of the Lower Limb
258
258

The Hip Joint
259
•
The Knee Joint.
266
277
277
278
The Symphysis Pubis.
216
lation
.
278
The Articulations of the Ribs with
The Ankle Joint.
.
279
the Vertebræ
218
The Tarsal Joints
282
The Costo-central Articulation
219
The Costo-transverse Articula-
The Calcaneo-astragaloid Union
The Posterior Calcaneo-astraga-
282
tion
221
loid Joint.
282
The Articulations at the Front of
the Thorax
222
The Anterior Calcaneo-astraga-
loid Joint
283
•
The Chondro-sternal Articula-
tions
222
The Articulations of the Anterior
Part of the Tarsus
285
The Costo-chondral Joints.
224
The Cubo-scaphoid Union
285
The Union of the Segments of
the Sternum
224
The Scapho-cuneiform Articu-
lation.
285
.
The Interchondral Articulations
Movements of the Thorax as a whole
The Articulations of the Upper Ex-
tremity
225
225
The Intercuneiform Articula-
tions
286
The Cubo-cuneiform Articula-
227
286
The Sterno-clavicularArticulation 227
The Scapulo-clavicular Union
. 230
230
234
·
The Elbow Joint.
239
The Union of the Radius with the
Ulna
241
The Acromio-clavicular Joint.
The Coraco-clavicular Union. 231
The Proper Scapular Ligaments 232
The Shoulder Joint
The Medio-tarsal or Transverse
Tarsal Joints
The Astragalo-scaphoid Articu-
lation.
The Calcaneo-cuboid Articula
tion.
The Tarso-metatarsal
tions
The Internal Tarso-metatarsal
286

. 287
. . 288
Articula
metat
. 290
The Superior Radio-ulnar Joint
The Mid Radio-ulnar Union .
The Inferior Radio-ulnar Joint
242
Joint
•
290
242
243
The Middle Tarso-metatarsal
Joint
291
.
The Radio-carpal Articulation
The Carpal Joints
245
The Cubo-metatarsal Joint.
291
249
The
Intermetatarsal
Articula-
•
The Union of the First Row of
tions
292
Carpal Bones .
249
The Union of the Heads of the
The Union of the Pisiform with
Metatarsal Bones.
293
the Bones of the First Row
249
•
The Metatarso-phalangeal Articu-
The Medio-carpal Joint
The Carpo-metacarpal Joints
The Union of the Second Row of
Carpal Bones
The Four Inner Carpo-metacarpal
lations
293
250
The Metatarsophalangeal
250
253
Joints of the Four Outer
Toes
293
The Metatarso - phalangeal
Joints.
253
Joint of the Great Toe
293
The Carpo-metacarpal Joint of
the Thumb
The Interphalangeal Joints
294
254
Morphology of Ligaments
294
CONTENTS
xi
SECTION III
THE MUSCLES
By J. N. C. DAVIES-COLLEY
General Remarks on Muscles
Muscles of the Upper Extremity--
Posterior Division of the Group
of Muscles passing from the
PAGE
296

Trunk to the Upper Extremity 3020
First Layer.
Second Layer
. 302
305-308
Anterior Division of the Group of
Muscles passing from the
Trunk to the Upper Extremity 308
First Layer
Second Layer
Third Layer.
. 309-311
. 311-313
313-315
Muscles which pass from the
Scapula to the Upper Limb 315-321
Group of Muscles which move
the Elbow Joint .
Fascia of the Upper Arm
Extensors of the Forearm
PAGE

Muscles of the back of the Leg 391
First Layer
.90 391-393
Second Layer
394-396
Third Layer
396
Fourth Layer
398
The Fascia and Muscles of the
Sole of the Foot
399
First Layer.
401-403
Second Layer
403-405
Third Layer.
405-408
Fourth Layer
408
200 Muscles of the Front of the Leg 410-414
Muscle on the Dorsum of the Foot 415
Muscles on the Outer Side of the
Leg.
415-417
Muscles of the Thorax
Thorax
417-422
321
The Diaphragm.
423
•
321
The Abdominal Parietes
425
.
Flexors of the Forearm
322-325
The Abdominal Muscles
425

326
Anterior Vertical Muscles
426
·
Muscles of the Forearm
327
•
Transverse and Oblique Muscles 428-435
Muscles of the Front of the Fore-
Posterior Vertical Muscle
435
arm.
328
Muscles of the Back
436
First Layer
328-332
Third Layer
436-438
Second Layer
332-335
Third Layer
335-338
arm.
ence
Eminence
Muscles of the Lower Extremity
Fourth Layer
Radial Group of Muscles
Muscles of the Back of the Fore-
Superficial Layer
Deep Layer.
The Fascia of the Hand.
The Palmar Fascia .
Muscles of the Hand
Superficial
Deep Muscles of the Palm
Central Group
Muscles of the Thenar Emin-
Muscles of the Hypothenar
Muscles and Fascia of the Thigh. 364
Muscles of the Front of the
338
.339-342
General Arrangement of the Muscles
acting upon the Spinal Column. 438
The Vertebral Aponeurosis.
Fourth Layer.
36 Fifth Layer.
342
.
342-346
346-351
351
.
351
•
352
•
Scalp
352
·
354
354-358
Sixth Layer
Seventh Layer
The Suboccipital Muscles
Muscles of the Head and Neck
Superficial Muscles of Neck
Muscles of the Eyelids and Eye-
brows
Extrinsic Muscles of the Auricle.. 458
Muscles of the Nose
438
•
439
440-445
446-449

449
•
450
452
and
452-455
455-457
459
.
358-362
Muscles of the Mouth
460
.
Transverse Muscles of the Mouth
462
.
363
Labial Group of Muscles
Muscles of Mastication
Angular Muscles of the Mouth
Muscles radiating from the Mouth. 468
Muscles and Fascia of the Front of the
464

•
466
Thigh
The Gluteal Muscles
First Layer..
Second Layer.
Third Layer.
468-472
366-371
370
Neck.
472
370-373
First Group
473
373
Second Group-Infra-hyoid
475
374
. 475
375-379
477
478-480
480-483
The External Rotators of Thigh
The Adductors of the Thigh 379-384
The Hamstring Muscles 384-387
The Anterior Muscles of the
Thigh
The Deep Fascia of the Leg and
Annular Ligaments.
6.387
390
Superficial Layer
Second Layer
Third Group-Supra-hyoid
Extrinsic Muscles of the Tongue
Deep Muscles of the Front of the Neck 483
Outer Group
Inner Group
Abnormal Muscles. (By J. Bland
Sutton)
.
483
485
487
xii
CONTENTS
SECTION IV
ARTERIES, VEINS, AND LYMPHATICS
By W. J. WALSHAM
PAGE
PAGE
The Arteries
491
•
Branches
. 600
The Pulmonary Artery
The Right
491
Internal Iliac Artery
600
493
Variations
600
Aorta
The Left
The Systemic Arteries
The Aorta
Arch of the Aorta
•
Variations of the Arch of the
Aorta
•
Branches of the Arch of the
Coronary Arteries and their
Variations
Innominate Artery
Branches and Variations
Common Carotid Arteries
Common Carotid.
495
495
sion.
495
•
Branches of Posterior Divi-
Branches of Anterior Divi-
601-604
495
sion
·
.604-611

External Iliac Artery
. 611
500
.
Branches and Variations
.
612
Collateral Circulation
•
.
612
. 501
Femoral Artery
.
613
Branches and Variations
. 616
502
Popliteal Artery.
. 621
503
504
•
Posterior Tibial Artery
504
·
Thoracic Portion of Left
505
Common Carotid in the
Branches and Variations
Branches
External Plantar Artery
Branches
·
Internal Plantar Artery
. 623
626
. 627
628
630
631
Neck
506
•
Branches
•
·
632
Branches and Variations
509
Anterior Tibial Artery.
•
632
External Carotid Artery
509
Branches
634
Branches and Variations 510-527
Dorsalis Pedis Artery
•
634
Internal Carotid Artery.
528
Branches
636
Branches.
530-536
Variations
Branches
Subclavian Artery
Distribution of the Cerebral
Arteries
Axillary Artery
536
•
The Veins
638

539
540-552
544
.
552
Branches and Variations
553
Brachial Artery.
559
Branches and Variations
561
Ulnar Artery.
Superficial Palmar Arch.
Variations
Branches
Radial Artery
Variations
Branches
Deep Palmar Arch
Branches and Variations
Descending, or Thoracic Aorta
Visceral Branches .
Parietal Branches
Abdominal Aorta
Variations
Parietal Branches
Visceral Branches
Terminal Branches
Middle Sacral Artery
Branches and Variations
Common Iliac Arteries
Variations
Collateral Circulation
563
•
Branches and Variations.
565
568
.
569
•
570
571
572
573
. 576
Veins of the Thorax
Pulmonary Veins
Vena Cava Superior
Innominate, or Brachio-cepha-
lic Veins
Variations
Azygos Veins
Veins of the Heart
Veins of the Head and Neck.
Superficial Veins of the Head
and Neck.
•
Deep Veins of the Head and
Neck
Veins of the Diploë
Venous Sinuses of the Cra-
nium
Veins of the Brain
638
639
639
640
•
642
642
646
•
•
648
648-655

·
655
•
655
656
661

. 576
Veins of the Nasal Cavities.
663
579
Veins of the Ear.
663
•
.
. 579
Veins of the Orbit
663
. 581
Veins of the Pharynx and
. 584
Larynx
•
665
. 585
Deep Veins of the Neck.
665
•
586-588
.
Spinal Veins
•
667
588-597
Veins of the Abdomen and
. 598
Pelvis
669
598
Inferior Vena Cava.
669
•
•
598
Variations
•
672
598
Common Iliac Veins
•
672
599
·
•
600
Variations
Portal Vein and its Tributaries
. 673
676
•
CONTENTS
xiii
Veins of the Pelvis
Veins of the Upper Extremity
Superficial Veins of the Upper
Extremity
Deep Veins of the Upper
Extremity
676
•
678
•
678
682
•
PAGE
Deep Lymphatic Vessels and
Glands of the Upper Ex-
tremity
•
Lymphatics of the Thorax
Parietal Lymphatic Vessels and
Glands of the Thorax
PAGE


693
695
695
•
.
Veins of the Lower Extremity . 683
Superficial Veins of the Lower
Visceral Lymphatic Vessels and
Glands of the Thorax
697
•
Extremity
. 683
Thoracic Duct
698
Extremity
The Lymphatics
Deep Veins of the Lower
Lymphatics of the Head and
Neck
Superficial Lymphatic Vessels
and Glands of the Head and
Neck
Variations
699
.685
Lymphatics of the Abdomen and
Pelvis.
•
699
. 688
688
Parietal Lymphatic Vessels and
Glands of the Abdomen and
Pelvis
699
689
Visceral Lymphatic Vessels and
Glands of the Abdomen and
Pelvis.
Deep Lymphatic Vessels and
Glands of the Head and
Neck
691
Lymphatics of the Upper Extre-
mity
693
Lymphatics of the Lower Ex
tremity
Superficial Lymphatic Vessels
and Glands of the Lower
Extremity
•
702
705
705
•
Superficial Lymphatic Vessels
and Glands of the Upper
Extremity
693
Deep Lymphatic Vessels and
Glands of the Lower Ex-
tremity
707
SECTION V
THE NERVOUS SYSTEM
By H. ST. JOHN BROOKS

Lymphatics of the Brain and
Third or Mandibular Division 801
Submandibular (Submaxil-
lary) Ganglion.
Otic Ganglion.
. 805
. 805
Sixth or Abducent Nerve . 805
Neurology
. 708
The Meninges
710
Spinal Cord
717
The Encephalon
. 718

Base of the Brain
719
Cerebral Hemispheres
720
Lobes of Cerebral Hemispheres
with the Fissures and Convolu-
tions
723
Basal Ganglia of the Hemispheres 739
The Thalamencephalon.
745
The Mesencephalon
749
.
The Epencephalon.
753
The Metencephalon
. 760
.
766
771
External Characters
774
. 776
778
Cranio-cerebral Topography
The Spinal Cord
Internal Structure
Deep Origin of the Spinal Nerves
The Peripheral Nervous System
Cranial Nerves
First or Olfactory Nerve.
Second or Optic Nerve
Seventh or Facial Nerve
Eighth or Auditory Nerve
Ninth or Glosso-pharyngeal
Nerve.
. 806
. 811
813
Tenth or Pneumogastric Nerve 815
Eleventh or Spinal Accessory
Nerve
819
Twelfth or Hypoglossal Nerve 820
Spinal Nerves
822
·
Posterior Primary Divisions
Anterior Primary Divisions
825
·
828
•
Cervical Nerves
828
·
786
Cervical Plexus
Superficial Branches
Deep Branches
Brachial Plexus
Branches given off
above the Clavicle
Branches given off
829
. 829
. 831
832
834
below the Clavicle
835
.
Thoracic Nerves
843
846
846
853
853
.
854
. 786
. 788

. 790
. 791
793
.794
9. 797
Third or Oculo-motor Nerve
Fourth or Trochlear Nerve
Fifth or Trigeminal Nerve
First or Ophthalmic Division 795
Lenticular Ganglion
Second or Maxillary Division 797
Meckel's Ganglion.
800
Lumbar Nerves
Lumbar Plexus
Sacral and Coccygeal Nerves
Fourth Sacral Nerve.
Coccygeal Plexus
xiv
CONTENTS
PAGE
PAGE
Sacral Plexus
. 854
The Great Sciatic Nerve.
Inferior Cervical Ganglion 867

. 858
Thoracic Portion
.
. 868
Sympathetic Nerves
. 863
Lumbar Portion.
. 869
Gangliated Cords of
the
Sacral Portion
. 869
Sympathetic
. 864
Great Prevertebral Plexuses .
869
Cervical Portion
. 864
Cardiac Plexus
.
869
glion
Superior Cervical Gan-
Middle Cervical Ganglion 867
SECTION VI
ORGANS OF SPECIAL SENSE
BY R. MARCUS GUNN AND ARTHUR HENSMAN
Solar Plexus
. 870
. 865
Hypogastric Plexus.
. 871
Pelvic Plexuses
873
The Eye
. 874
The Eyelids
. 902
The Eyeball and its Surroundings 874
General Surface View
Examination of the Eyeball . 878
The Lachrymal Apparatus
.904
. . 874
The Ear
. 907
The External Ear.
. 907
Cavity of the Orbit .
.890
The Middle Ear
. 910
General Arrangement of its
The Internal Ear or Labyrinth. 916
Contents
. 890
The Tongue
. 921
The Optic Nerve
.897
The Nose
. 926
Blood-vessels and Nerves of the
Orbit
. 899
SECTION VII
THE THORAX, INCLUDING THE ORGANS OF VOICE,
RESPIRATION, AND CIRCULATION
BY ARTHUR HENSMAN
The Thorax.
.935
The Organs of Circulation
The Organs of Voice
.938
The Pericardium
The Larynx.
.938
The Trachea
.950
The Bronchi
.952
The Thyroid Body or Gland
.952
The Thymus Body or Gland.
.955
The Organs of Respiration
.958
The Vessels and Nerves
The Lungs
.958
The Pleuræ
The Heart
.962
.962
.. 963
The Openings and their Valves. 969
The Relations of the Chief Open-
ings one to the other and to
the Chest Wall
. 972
.972
Peculiarities of the Foetal Heart 977
.958
SECTION VIII
THE ORGANS OF DIGESTION
BY ARTHUR HENSMAN AND FREDERICK TREVES
The Organs above the Diaphragm . 978 The Abdominal Viscera
The Mouth
The Peritoneum
The Palate.
The Salivary Glands
The Pharynx
The Esophagus
989
. 978
989
. 980
The Abdomen
994
982
The Stomach.
996
985
The Intestines
. 1000
·
987
The Small Intestine
. 1000
The Large Intestine
. 1005
CONTENTS
XV
PAGE
The Evolution of the Peritoneum
and an Explanation of its Arrange-
ment in the Human Body
The Liver
1012
•
Varieties of the Liver
. 1023
The Pancreas.
. 1023
The Spleen.
. 1025
SECTION IX
THE URINARY AND REPRODUCTIVE ORGANS
BY WILLIAM ANDERSON
PAGE
1028
The Kidneys.
. 1042
The Uterus.
. 1081
The Suprarenal Bodies
. 1050
The Renal Ducts
. 1051
The Fallopian Tubes or Oviducts 1088
The Ovaries
. . 1090
The Bladder
. 1053
The Male Reproductive Organs
. 1058
and its Appendages.
The Prostate
11058
Vessels and Nerves of the Uterus
Development of the Genito-urinary
. 1091
The Testicles with their Appen-
dages and Coverings
Organs
. 1092
. 1060
The Perinæum
. 1096
The Spermatic Cord
. 1068
The Male Perinæum
. 1096
The Penis.
. 1069
The Pelvic Fascia and Muscles. 1098
The Urethra
. 1073
The Perinæum Proper.
. 1103
The Female Organs of Generation
. 1076
The Female Perinæum .
. 1107
The Vagina
. 1079
The Mammæ
. 1108

1111
•
•
. 1111
SECTION X
SURGICAL AND TOPOGRAPHICAL ANATOMY
By W. H. A. JACOBSON
Superficial Anatomy of the Head and
Neck
The Head and Face
The Eyelids and Lachrymal Ap-
The Back
Superficial Anatomy of the Upper
Limb.
The Shoulder
. 1170
1. 1180
. 1180
paratus
The Mouth.
The Palate
The Neck
The Abdomen
1119
The Arm
.1186
. 1121
The Elbow
. 1188
. 1124
The Forearm
. 1193
. 1124
The Wrist and Hand.
. 1198
Superficial Anatomy of the Thorax . 1134
The Perinæum and Genitals
Female External Genitals
The Lower Extremity
. 1210
. 1141
The Thigh.
. 1210
. 1150
The Buttocks
. 1216
. 1156
The Knee
. 1220
Hernia
. 1159
Parts involved in
The Popliteal Space
1225
Inguinal
The Leg
1228
Hernia
. 1159
The Ankle
1233
Parts involved in
Femoral
Hernia
1165
•
The Foot
Arches of the Foot
1238
1242
Parts involved in Umbilical
The Regions of the Abdomen
1247
•
Hernia
1169
INDEX
6.1251
LIST OF ILLUSTRATIONS
FIG.
1. The Tibia and Fibula in section, to show the Epiphyses
2. A Vertebral Centrum to show the Pressure Curves
3. A Diagram to show the Pressure and Tension Curves of the Femur
PAGE
3
4
5
After Wagstaffe
4. A Diagram showing Pressure and Tension Curves in the Head of the Humerus.
5
After Wagstaffe
5. A Thoracic Vertebra (side view).
6. A Thoracic Vertebra
7. A Cervical Vertebra
8. The First Cervical Vertebra or Atlas
9. The Axis
10. The Cervical Vertebræ (anterior view)
11. The Cervical Vertebræ (posterior view)
12. Peculiar Thoracic Vertebræ
13. A Lumbar Vertebra (side view)
14. A Lumbar Vertebra. (Showing the compound nature of the transverse pro-
cesses. Upper view)
15. Variation in the Fifth Lumbar Vertebra
16. A Variation in the Fifth Lumbar Vertebra
17. The Sacrum and Coccyx (anterior view)
18. The Sacrum (posterior view).
19. Base of Sacrum .
20. The Spine (lateral view)
21. A Divided Thoracic Vertebra
22. A Vertebra at Birth
23. Lumbar Vertebra at Eighteenth Year, with Secondary Centres
24. Immature Atlas (third year)
25. Development of the Atlas
26. The Axis (from an Adult) in section
27. An Immature Cervical Vertebra
28. Ossification of the Fifth Lumbar Vertebra
29. Morphology of the Transverse and Articular Processes
30. The Occipital (external view)
31. Occipital Bone (cerebral surface)
Channels
•
669
7
8
9
10
11
Modified from Gray
12
13
14
After Turner
14

After Turner
15
16
17
17
19
After Turner
20
21
21
22
22
22
23
23
24
27
28
28
29
31
31
32
33
34
34
36
32. Cerebral Surface of the Occipital, showing an occasional disposition of the
33. The Foramen Magnum at the Sixth Year
34. The Occipital at Birth (anterior view)
35. The Occipital with a separate Interparietal
36. The Sphenoid (viewed from above)
37. The Left Half of the Sphenoid .
38. The Sphenoid (anterior view)
39. The Right Half of the Sphenoid (anterior view)
40. The Under Surface of the Pre-Sphenoid at the Sixth Year
LIST OF ILLUSTRATIONS
xvii
FIG.
41. The Sphenoid at Birth
42. The Jugum Sphenoidale
43. The Left Temporal Bone (outer view)
75. The Palate Bone (posterior view)
44. The Left Temporal Bone (inner view)
45. The Foramina in the Fundus of the Left Internal Auditory Meatus of a
Child at Birth (diagrammatic)
46. The Left Temporal Bone (inferior view).
47. The Temporal Bone with Muscle Attachments
48. The Inner Wall of Tympanum
49. The Left Osseous Labyrinth (from a cast)
50. The Cochlea in sagittal section
51. The Temporal Bone at Birth (outer view)
52. The Temporal Bone at Birth (inner view)
53. The Temporal Bone at the Sixth Year
54. The Mastoid Antrum at the Third Year.
55. The Mastoid Antrum at the Ninth Year
56. The Mastoid Antrum of an Adult .
57. The Left Parietal (outer surface)
58. The Left Parietal (inner surface)
59. The Frontal (anterior view)
60. The Frontal Bone (inferior view)
61. The Frontal Bone at Birth.
62. Section through the Nasal Fossa to show the Mesethmoid
63. The Ethmoid (side view)
PAGE
36
37
37
38
39
40
41
43
After Henle
44
After Henle
45
46
46
46
47
After Symington 47
After Symington
After Symington
64. Section through the Nasal Fossa to show the Lateral Mass of the Ethmoid
65. The Sphenoidal Turbinal at the Sixth Year
66. The Sphenoidal Turbinals from an Old Skull
67. The Inferior Turbinal, Adult Sphenoidal Turbinal, and Lachrymal Bones
68. The Vomer (side view)
69. The Vomer at Birth
70. The Left Nasal Bone
•
71. The Left Maxilla (outer view)
72. The Left Maxilla (inner view)
73. Ossification of the Maxilla .
74. The Left Palate Bone (inner view)
76. The Left Malar Bone
48
49
49
51
51
52
53
54
55
56
56
57
58
59
60
61
61
63
65
65
67
77. The Mandible (outer view)
69
78. The Mandible (inner view)
70
79. The Mandible at Birth
71

80. The Skull of an Old Woman eighty-three years old, to show the changes in the
Mandible and Maxilla
71
81. The Hyoid.
72
82. The Ear Bones
Modified from Henle
74
83. The Skull (norma lateralis)
76
84. A Section of the Skull, showing the Inner Wall of the Orbit, the Base of the
Antrum, and the Spheno-maxillary Fossa
77
85. Hard Palate of a Child five years old.
78
86. The Skull (norma basilaris)
87. The Skull (norma basilaris)
88. The Skull (norma facialis) .
89. The Skull (norma facialis)
90. The Inner Wall of the Orbit
91. Section through the Nasal Fossa to show the Septum
92. Section through the Nasal Fossa to show the Outer Wall with the Meatuses
93. The Posterior Nares
80
81
82
83
85
86
87
88
94. The Skull in sagittal section.
95. The Skull in horizontal section
89
90
96. The Skull in horizontal section
91
a
xviii
LIST OF ILLUSTRATIONS
FIG.
97. The Teeth of an Adult
98. A Molar Tooth in section, and a Canine Tooth
99. The Temporary Teeth
100. The Chondro-Cranium
101. The Cranium at Birth
102. The Cranium at Birth
103. The Cranium at Birth in sagittal section
104. The Occipital at Birth.
105. The Sphenoid at Birth
106. The Temporal Bone at Birth.
107. The Temporal Bone at Birth (outer view).
108. The Temporal Bone at Birth (inner view)
109. The Frontal at Birth .
110. The Maxilla at Birth
111. The Mandible at Birth
112. The Seventh Rib of the Left Side (seen from below)
113. The First and Second Ribs
114. The Vertebral Ends of the Tenth, Eleventh, and Twelfth Ribs
115. Rib at Puberty
PAGE
94
95
96
97
98
99
99
100
•
100
•
101
•
101
•
102
102
103
103
107
109
109
. 111
116. The Thorax at the Eighth Month.
112
117. The Sternum (anterior view)
114
118. The Sternum (posterior view)
115
119. Two Stages in the Formation of the Cartilaginous Sternum
120. The Thorax (front view)
After Ruge 116
117
126. The Left Humerus (anterior view)
127. The Left Humerus (posterior view)
attachments (anterior view)
129. Ossification of the Humerus
130. The Head of the Humerus at the Sixth Year (in section)
131. Upper End of Left Ulna (outer view)
132. The Left Ulna and Radius (antero-internal view).
133. The Left Ulna and Radius (postero-external view)
135. Posterior View of the Lower End of the Radius and Ulna
121. The Left Clavicle (superior surface)
122. The Left Clavicle (inferior surface)
123. The Left Scapula (dorsal surface)
124. The Left Scapula (ventral surface)
125. Ossification of the Scapula
128. The Left Humerus with a Supracondyloid Process and some Irregular Muscle-
118
118
120
121
123
125
126
127
128
130
131
.
132
.
133
134. The Articular Facets on the Lower End of Left Radius and Ulna
136. Ossification of the Radius and Ulna
137. The Left Hand (dorsal surface).
138. The Left Hand (palmar surface)
139. The Left Scaphoid
140. The Left Semilunar
141. The Left Cuneiform
142. The Left Pisiform
143. The Left Trapezium
144. The Left Trapezoid
145. The Left Magnum
146. The Left Unciform
135
135
136
138
•
139
140
140
140
140
.
141
141
141
142
147. The First (Left) Metacarpal
148. The Second (Left) Metacarpal
149. The Third (Left) Metacarpal
143

144
144
151. The Fifth (Left) Metacarpal
150. The Fourth (Left) Metacarpal
152. The Phalanges of the Third Digit of the Hand (dorsal view).
153. Ossification of the Metacarpals and Phalanges
154. The Left Hip-Bone (internal surface)
145
•
146
•
147
147
150
LIST OF ILLUSTRATIONS
xix
159. The Pelvis (Male)
160. The Left Femur (anterior view)
161. The Left Femur (posterior view)
162. The Femur at Birth
FIG.
155. The Left Hip-Bone (posterior view)
156. An Immature Innominate Bone, showing a Cotyloid Bone
157. The Pelvis of a Foetus at Birth, to show the three portions of the Innominate
Bones
158. Hip-Bone, showing Secondary Centres
PAGE
151
. 152

152
154
•
155
.
158
159
160
.
164. The Left Patella
163. The Left Femur at the Twentieth Year (posterior view)
165. The Left Tibia and Fibula (anterior view)
•
161
•
162
•
164
166. The Left Tibia and Fibula (posterior view)
.
165
167. The Tibia and Fibula at the Sixteenth Year
168. The Left Foot (dorsal surface)
167
.
. 170
169. The Left Foot (plantar surface)
170. The Left Astragalus (plantar view)
171. An Astragalus with the Os Trigonum
171
.
172
173
175. The Left Cuboid (inner view)
172. The Left Calcaneum (dorsal view)
173. The Calcaneum at the Fifteenth Year, showing the Epiphysis.
174. The Left Cuboid (inner view)
176. The Left Scaphoid (anterior view).
177. The Left Scaphoid, showing a Facet for the Cuboid
178. The Left Internal Cuneiform (internal surface)
179. The Left Internal Cuneiform (external surface)
180. The Left Middle Cuneiform (internal surface)
181. The Left Middle Cuneiform (external surface)
182. The Left External Cuneiform (internal surface)
183. The Left External Cuneiform (external surface)
184. The First (Left) Metatarsal
185. The Second (Left) Metatarsal
186. The Third (Left) Metatarsal
187. The Fourth (Left) Metatarsal
174
.
174
.
175
•
176
177
177
•
. 178
178
178
178
179
•
179
180

180
181
.
181
•
188. The Fifth (Left) Metatarsal
182
.
189. The Phalanges of the Middle Toe
183
•
190. A Longitudinal Section of the Bones of the Lower Limb at Birth
191. The Secondary Ossific Centres of the Foot
184
.
185
.
192. External View of the Temporo-mandibular Joint.
191
193. Internal View of the Temporo-mandibular Joint
191
194. Vertical Section through the Condyle of Jaw to show the two Synovial Sacs
and the Interarticular Fibro-Cartilage
192
195. Anterior View of the Upper End of the Spine
•
194
.
196. Vertical Antero-posterior Section of Spinal Column through Median Line,
showing Ligaments .
197. Horizontal Section through the Lateral Masses of the Atlas and the Top of the
Odontoid Process
195
197
198. The Superficial Layer of the Posterior Common Vertebral Ligament has been
removed to show its Deep or Short Fibres. (These deep fibres form the Occipito-
cervical Ligament)
199
199. Vertical Transverse Section of the Spinal Column and the Occipital Bone to
show Ligaments
199
•
200. Horizontal Section through an Intervertebral Disc and the corresponding Ribs
201. The Anterior Common Ligament of the Spine, the Stellate, and the Superior
Costo-transverse Ligaments
201
202
202. Posterior Common Ligament of the Spine (Thoracic Region)
203. Posterior Common Ligament (Lumbar Region)
203
•
204
204. Ligamenta Subflava in the Lumbar Region
206
•
205. The Interspinous and Supraspinous Ligaments in the Lumbar Region.
207
•
a 2
XX
LIST OF ILLUSTRATIONS
FIG.
206. Anterior View of the Pelvis
207. Vertical Antero-posterior Section of the Pelvis
PAGE
210
212
208. Sacro-sciatic Ligaments (posterior view)
213
209. Ligaments connecting Sacrum and Coccyx posteriorly
215
210. Anterior View of the Symphysis Pubis (Male), showing the Decussation of the
Fibres of the Anterior Ligament
216
211. Anterior View of the Symphysis Pubis (Female), showing the greater width
between the Bones.
. 217
212. Posterior View of the Symphysis Pubis, showing the Backward Projection of the
Symphysial Substance and the Decussation of the Fibres from the Inferior
Pubic Ligament.
.
217
213. Section of the Symphysis to show the Synovial Cavity
214. The Capsular Ligaments of the Costo-vertebral Joints.
215. Showing the Anterior Common Ligament of the Spine, and the Connection of
the Ribs with the Vertebræ
218
219
220
216. Horizontal Section through the Intervertebral Disc and Ribs
220
217. The Sternum.
223
218. Diagram of Axis of Rib-movement
After Kirkes 226
219. Posterior View of the Sterno-clavicular Joint
220. Anterior View of Sterno-clavicular Joint
221. Section through Sterno-clavicular Joint
228
•
228
229
222. Anterior View of Shoulder, showing also Coraco-clavicular and Coraco-acromial
Ligaments
231
223. Posterior View of the Shoulder Joint, showing also the Acromio-clavicular
Joint and the Proper Ligaments of the Scapula
•
224. Vertical Section through the Shoulder Joint to show the Gleno-humeral Liga-
ment
233
234
225. Foetal Shoulder Joint, showing the Gleno-humeral Ligament, and also the Short
Head of the Biceps being continuous with the Coraco-acromial Ligament . 235
226. Outer View of the Shoulder Joint, showing the Coraco-humeral and Transverse
Humeral Ligaments.
227. Biceps Tendon, bifurcating and blending on each side with the Glenoid Fibro-
cartilage.
236
237
228. Internal View of the Elbow Joint.
240
229. External View of the Elbow Joint
230. Orbicular Ligament
231. Anterior View of Wrist
232. Posterior View of Wrist
233. Front of Wrist with Anterior Annular Ligament
240
•
242.
246
247
248
•
234. Posterior View of Wrist, with Capsule cut to show Articular Surfaces.
251
235. Synovial Membranes of Wrist, Hand, and Fingers
252
236. Anterior and Posterior View of Ligaments of the Fingers
237. Anterior View of the Capsule of the Hip Joint.
256
260
238. Posterior View of the Capsule of the Hip Joint
261
239. Section through the Hip Joint, showing the Cotyloid Ligament, Ligamentum
Teres, and Retinacula
262
240. Hip Joint after dividing the Capsular Ligament, and disarticulating the Femur 263
241. Portions of Ischium and Pubes, showing the Cotyloid Notch and the Ligamen-
tum Teres attached outside the Acetabulum.
263
•
242. Ligamentum Teres, lax in flexion.
265
243. Ligamentum Teres, very lax in complete Extension .
265
244. Ligamentum Teres, drawn tight in Flexion combined with Rotation outwards
and Adduction
266
245. Posterior View of the Knee Joint
268
•
246. Anterior View of the Internal Ligaments of the Knee Joint.
269
.
247. Structures lying on the Head of the Tibia (Right Knee)
270
•
248. Anterior View of the Knee Joint, showing the Synovial Ligaments
271
249. Vertical Section through the Knee Joint in the Antero-posterior Direction
250. The Lateral Ligaments of the Knee in Flexion and Extension
273
•
274
LIST OF ILLUSTRATIONS
xxi
FIG.
251. Section of Knee, showing Crucials in Extension
252. Crucial Ligaments in Flexion
253. Inner View of the Ankle and the Tarsus, showing the Groove for the Tendon of
the Tibialis Posticus
254. Ligaments seen from the Back of the Ankle Joint.
255. External View of the Ligaments of the Foot and Ankle
256. View of the Foot from above, with the Astragalus removed to show the Inferior
and External Calcaneo-scaphoid Ligaments
257. Ligaments of Sole of Foot. Long Plantar
258. Section to show the Synovial Cavities of the Foot
259. Diagram showing Penniform Muscle, the Peroneus Longus; and Bipenniform,
the Tibialis Posticus
260. Diagram illustrating the advantage of Oblique Insertion of Tendons
PAGE
275
.
276
10.9. 280
. 281
. 284
287
289
294
... 298
. 300
261. Diagram illustrating the advantage of Oblique Insertion of Tendons
262. First Layer of Muscles of the Back
. 301
303
263. The Levator Anguli Scapula and Rhomboidei
306
264. The Pectoralis Major and Deltoid
309
270. Superficial View of the Front of the Upper Arm
275. Front of Forearm: Third Layer of Muscles .
277. Tendons upon the Dorsum of the Hand
265. The Subclavius and the Upper Portion of the Serratus Magnus
266. The Pectoralis Minor, Obliquus Internus, Pyramidalis, and Rectus Abdominis
267. Serratus Magnus
268. Back View of the Scapular Muscles and Triceps
269. Front View of the Scapular Muscles
271. Deep View of the Front of the Upper Arm
272. Front of the Forearm: First Layer of Muscles.
273. Front of the Forearm: Second Layer of Muscles .
274. Diagram of the Great Palmar Bursa .
276. Muscles of the Radial Side and the Back of the Forearm
278. The Deep Layer of the Back of the Forearm
279. Diagram of a Vertical Section through the Middle of the Hand
280. The Superficial Muscles of the Palm of the Hand
281. The Palmar Interossei
282. The Dorsal Interossei
311
312
•
314
•
318
320
.
322
•
324
329
333
334
336
dab. 340
343
347
353
355
356
357
283. The Deeper Muscles of the Palm of the Hand
359
286. Psoas, Iliacus, and Quadratus Lumborum.
288. The External Rotators and the Hamstring Muscles
284. The Pronator Quadratus and Deep View of the Palm
285. Obliquus Externus and Fascia Lata
287. Muscles of the Front of the Thigh
289. The Deep Muscles of the Front of the Thigh
290. The Deep Muscles of the Back of the Thigh
291. Superficial Muscles of the Back of the Thigh and Leg
292. The Deep Muscles of the Back of the Leg.
293. First Layer of the Muscles of the Sole
294. Second Layer of the Muscles of the Sole
295. Third Layer of the Muscles of the Sole.
296. Fourth Layer of the Muscles of the Sole
297. The Muscles of the Front of the Leg
·
361
365
367
370
376

. 380
381
392
397
400
403
406
409
411
298. The Muscles of the Dorsum of the Foot
414
299. The External Intercostals and Levatores Costarum
300. The Intercostal Muscles
418
•
420
301. The Muscles attached to the Back of the Sternum
422
302. Diaphragm
423
303. External Oblique and Ilio-tibial Band
7.429
304. Transversalis Abdominis and Sheath of Rectus.
433
305. The Third and Fourth Layers of the Muscles of the Back
437
306. The Fifth Layer of the Muscles of the Back
442
xxii
LIST OF ILLUSTRATIONS
FIG.
307. The Fifth Layer of the Muscles of the Back, after separating the Outer and
Middle Divisions
PAGE
308. The Sixth Layer of the Muscles of the Back
309. The Superficial Muscles of the Head and Neck
310. The Tensor Tarsi and Corrugator Supercilii
311. The Deeper Layer of the Muscles of the Face and Neck
312. The Temporal Muscle
313. The Pterygoid Muscles .
314. Anterior and Lateral Cervical Muscles
315. Side View of the Muscles of the Tongue
316. The Muscles of the Front of the Neck
317. Anterior View of the Heart with the Large Arteries and Veins
Royal College of Surgeons Museum
318. The Heart, with the Arch of the Aorta, the Pulmonary Artery, the Ductus
Arteriosus, and the Vessels concerned in the Foetal Circulation
St. Bartholomew's Hospital Museum
319. Diagram of the Relations of the Pulmonary Artery and its Right and Left
Branches
320. Posterior View of Heart and Greater Vessels
Royal College of Surgeon's Museum
321. The Arch of the Aorta, with the Pulmonary Artery and Chief Branches of the
Aorta
St. Bartholomew's Hospital Museum
322. Scheme of the Relations of the First Portion of the Arch of the Aorta.
323. Scheme of the Relations of the Transverse Portion of the Arch of the Aorta
324. The Heart and Great Vessels with the Root of the Lungs, seen from behind
St. Bartholomew's Hospital Museum
325. Scheme of the Relations of the Third Portion of the Arch of the Aorta
326. Scheme of the Coronary Arteries
444
447
.
453
457
463
470
471
•
474
482
486
492
.
492
494
494
496
497
•
498
•
499
•
500
502
327. Scheme of the Relations of the Innominate Artery
328. Scheme of the Relations of the Left Common Carotid and Left Subclavian
Arteries within the Thorax
504
505
329. The Common Carotid, the External and Internal Carotid, and the Subclavian
Arteries of the Right Side and their Branches
507
St. Bartholomew's Hospital Museum
330. The Collateral Circulation after Ligature of the Common Carotid and Subcla-
vian Arteries .
508
331. Scheme of Ascending Pharyngeal Artery
511
332. Scheme of Superior Thyroid Artery
. 512
333. Scheme of the Lingual Artery
514
334. Scheme of the Facial Artery
516
335. Scheme of Occipital and Posterior Auricular Arteries
. 519
336. Scheme of Internal Maxillary Artery
523
337. The Middle Meningeal Artery within the Skull
338. The Internal Carotid Artery, and Deep Branches of the External Carotid
Artery
339. The Ophthalmic Artery and Vein
340. The Arteries of the Brain
341. The Subclavian Artery
•
525
Royal College of Surgeons Museum 528
531
.
St. Bartholomew's Hospital Museum 535
538
342. Scheme of the Vertebral Artery
344. Scheme of the Internal Mammary Artery.
541
343. Diagram of the Anastomoses of the Scapular Arteries
345. Scheme of the Superior Intercostal Artery
346. The Lower Part of the Axillary, the Brachial, and the Radial and Ulnar
Arteries
347. The Dorsal Scapular Artery
348. The Posterior Circumflex Artery
349. The Anastomoses about the Scapula .
350. The Brachial Artery
.
Royal College of Surgeons Museum 554
Royal College of Surgeons Museum 556
St. Bartholomew's Hospital Museum 557
558
Royal College of Surgeons Museum 559
•
560
351. The Brachial Artery at the Bend of the Elbow
547
•
549
551
.
LIST OF ILLUSTRATIONS
xxiii
FIG.
PAGE
352. The Arteries of the Forearm, with the Deep Palmar Arch.
353. The Back of the Forearm, with the Posterior Interosseous Artery and Branches
564
of the Radial at the Back of the Wrist. Royal College of Surgeons Museum 567
354. Anastomoses and Distribution of the Arteries of the Hand
355. The Arteries of the Forearm and the Deep Palmar Arch
356. Diagram of the Relation of the Arteries of the Forearm to the Bones
357. The Bend of the Elbow

358. The Radial Artery at the Wrist
•
•
569
570
572
·
577
St. Bartholomew's Hospital Museum 573
Royal College of Surgeons Museum 575
359. Anastomoses and Distribution of the Arteries of the Hand
360. The Arch of the Aorta, the Thoracic Aorta, and the Abdominal Aorta, with the
Superior and Inferior Vena Cava and the Innominate and Azygos Veins . 578
361. Scheme of the Thoracic Aorta
362. Scheme of the Intercostal Artery
580
583
363. The Abdominal Aorta and its Branches, with the Inferior Vena Cava and its
Tributaries
.
584
364. Scheme of the Abdominal Aorta
.
586
365. The Coeliac Artery and its Branches
589
366. The Superior Mesenteric Artery and Vein.
593
367. The Inferior Mesenteric Artery and Vein
597
368. Side View of the Pelvis and Upper Third of Thigh, with the External Iliac,
Internal Iliac, and Femoral Arteries and their Branches
601
St. Bartholomew's Hospital Museum
369. The Gluteal Region with the Gluteal, Sciatic, and Pudic Arteries.
603
•
St. Bartholomew's Hospital Museum
370. Scheme of the Ovarian, Uterine, and Vaginal Arteries
370A.The Arteries of the Perinæum
371. Scheme of the Pudic Artery and its Branches
372. The Femoral Artery in Scarpa's Triangle
.
605
609
·
€ 610
615
St. Bartholomew's Hospital Museum
373. To show the Anastomoses of the Arteries of the Lower Extremity
617

After Smith and Walsham
374. Relations of the Popliteal Artery to Bones and Muscles
375. Side View of the Popliteal Artery
376. The Anastomoses about the Knee Joint (semi-diagrammatic)
377. The Popliteal, the Posterior Tibial, and the Peroneal Artery
378. The Plantar Arteries
St. Bartholomew's Hospital Museum 629
379. The Deep Plantar Arteries.
Royal College of Surgeons Museum 631
380. The Anterior Tibial Artery, Dorsal Artery of the Foot, and Anterior Peroneal
Artery, and their Branches
381. Diagram of the Distribution and Anastomoses of the Arteries of the Foot
381A.The Vena Cava Superior and the Innominate Veins
. 633
635
641
St. Bartholomew's Hospital Museum
382. The Superior and Inferior Vena Cavæ, the Innominate Veins, and the Azygos
Veins
622
623
. 625
626
643
383. The Coronary Sinus
646
384. The Scheme of the Coronary Veins.
647
385. The Superficial Veins and Lymphatics of the Scalp, Face, and Neck
649
386. The Veins of the Diploë
St. Bartholomew's Hospital Museum
656
387. The Venous Sinuses
St. Bartholomew's Hospital Museum 657
388. The Venous Sinuses (longitudinal section)
389. The Veins of the Orbit
658
•
664
.
390. The Spinal Veins .
391. The Abdominal Aorta and Inferior Vena Cava .
392. The Veins of the Stomach and Portal Vein
393. The Superior Mesenteric Vein
394. The Inferior Mesenteric Vein
•
667
•
670
.
674
675
676
395. The Bend of the Elbow with the Superficial Veins
680
St. Bartholomew's Hospital Museum
396. Superficial Veins and Lymphatics of the Forearm and Arm
681
xxiv
LIST OF ILLUSTRATIONS
FIG.
397. The Superficial Veins and Lymphatics of the Lower Limb
398. The Superficial Lymphatics of the Scalp, Face, and Neck
399. The Superficial Lymphatics of the Upper Limb and Axillary Glands
400. The Superficial Lymphatics of the Lower Limb
PAGE
684
690
694
706
712
401. Diagrammatic Sagittal Section of a Vertebrate Brain
After Huxley 708
402. Diagrammatic Horizontal Section of a Vertebrate Brain
After Huxley 709
403. Coronal Section of the Head passing through the Mastoid Process
Anatomical Department, Trinity College, Dublin
Head passing through the Posterior Horns of the
Anatomical Department, Trinity College, Dublin
405. The Cranium opened to show the Falx Cerebri, the Tentorium Cerebelli, and
the places where the Cranial Nerves pierce the Dura Mater
406. Coronal Section through the Great Longitudinal Fissure,
404. Coronal Section of the
Lateral Ventricles .
Meninges
407. The Cranial Nerves in the Base of the Skull
408. View of the Base of the Brain
713
Sappey 714
showing the
Key and Retzius 715
716
After Beaunis 719
409. The Fissures and Convolutions of the Cerebrum, viewed from above
410. Lateral View of the Fissures and Convolutions of the Cerebrum
411. Convolutions and Fissures on the Mesial and Tentorial Surfaces of the
Hemisphere
412. Mesial Section of Entire Brain.
721
723
. 730
After Henle 733
413. A Dissection of the White Matter of the Posterior Part of the Right Cerebral
Hemisphere (viewed from the inner side).
Schwalbe 734
735
414. Diagrammatic Coronal Section of the Third and Lateral Ventricles.
From Schwalbe, slightly modified
415. Coronal Section of the Hemispheres, passing through the Anterior Cornua of
the Lateral Ventricles. Anatomical Department, Trinity College, Dublin 736
416. Coronal Section of the Head, passing through the Posterior Horns of the
Lateral Ventricles
Anatomical Department, Trinity College, Dublin 737
417. A Dissection of the Descending Cornu of the Lateral Ventricle, with a Sagittal
Section through the Basal Ganglia
738
418. A Dissection showing the Free or Intraventricular Portion of the Caudate
Nucleus. The Mesial and Tentorial Surfaces of the Hemisphere are also
shown.
Anatomical Department, Trinity College, Dublin 739
419. Horizontal Section of the Cerebrum
After Landois and Stirling
420. Horizontal Section of the Cerebral Hemispheres
•
741
744
745
Anatomical Department, Trinity College, Dublin
421. Coronal Section through the Anterior Part of the Third Ventricle
Anatomical Department, Trinity College, Dublin
422. Coronal Section through the Middle Commissure of the Third Ventricle Schwalbe 747
423. Coronal Section through the Third Ventricle behind the Middle Commissure. 748
424. Deep Origin of the Third Nerve
425. Lateral View of Mesencephalon, Pons, and Medulla .
426. Inferior Surface of the Cerebellum
Gegenbaur
After Krause 750
Gegenbaur 751
755
Anatomical Department, Trinity College, Dublin
427. Right Half of the Encephalic Peduncle as seen from the inside of a Median
Section
Allen Thomson, after Reichert 757
428. Metencephalon, Mesencephalon, and Thalamencephalon, from the Dorsal
Surface
•
After Obersteiner 759
Schwalbe 762
763
429. Transverse Section through the Upper Part of the Pons
430. Transverse Section of the Pons near the Centre of the Fourth Ventricle.
Schwalbe
431. Transverse Section of the Medulla, a little above the Lower Extremity of the
Fourth Ventricle
After Krause 764
432. Transverse Section of the Medulla in the Region of the Decussatio Lemnisci 765
Schwalbe
Cunningham 768
433. Drawing of a Cast of the Head of an Adult Male
434. Drawing of a Cast of the Head of a Newly-born Male Infant Cunningham 770
.
LIST OF ILLUSTRATIONS
XXV
FIG.
435. Transverse Section through the Spinal Cord and its Membranes
PAGE
. 771
After Key and Retzius
Ellis 772
436. View of the Membranes of the Spinal Cord.
437. Posterior View of the Medulla Oblongata and of the Spinal Cord, with its
Coverings and the Roots of the Nerves
•
438. Anterior and Posterior View of the Spinal Cord
439. Sections through different Regions of the Spinal Cord
Hirschfeld and Leveillé 773
Modified from Quain 775
After Schwalbe 777
440. Diagram of the Tracts of the Spinal Cord and of the Deep Origins of the Spinal
Nerves
•
441. Surface Origin of the Cranial Nerves
442. Nerves of the Nasal Cavity
443. Deep Origin of the Third Nerve
. 780
After Allen Thompson.-Quain 787
444. Sections through the Origin of the Fourth Nerve
445. Nerves of the Orbit, from the Outer Side
789
After Krause 792
Stilling 793
From Sappey after Hirschfeld and Leveille
•
796
Beaunis 798
Henle 802
Krause 807
446. The Maxillary Nerve, seen from without
447. Distribution of the Mandibular Division of the Trigeminal Nerve.
448. Diagrammatic Lateral View of the Origin of the Facial Nerve.
449. Superficial Distribution of the Facial and other Nerves of the Head
After Hirschfeld and Leveillé
450. Transverse Section of the Pons, passing through the most Distal of the Striæ
Medullares
.
Krause
809
451. Distribution of the Pneumogastric Nerve, viewed from behind
452. Distribution of the Posterior Primary Divisions of the Spinal Nerves
453. Diagram of the Cervical Plexus.
454. Superficial Branches of the Cervical Plexus
455. Diagram of the Brachial Plexus
•
811
Krause 816
Henle
826
829
After Hirschfeld and Leveille 830
456. Distribution of Cutaneous Nerves on the Anterior and Posterior Aspects of the
Superior Extremity
. 833
836
837
Ellis 839
.
457. A Dissection showing the Arrangement of the Nerves in front of the Elbow
Anatomical Department, Trinity College, Dublin
458. Superficial Nerves of the Palm
459. A Dissection of the Cutaneous Nerves on the Dorsal Aspect of the Hand and
Fingers.
H. St. J. Brooks
460. Cutaneous Nerves of the Thorax and Abdomen, viewed from the side
After Henle
842
844
Modified from Paterson 847
461. Diagram of the Lumbar and Sacral Plexuses
462. Branches of the Lumbar and Sacral Plexuses, viewed from before
•
After Hirschfeld and Leveillé
·
848
Ellis 850
463. Anterior Crural and Obturator Nerves.
464. Distribution of Cutaneous Nerves on the Posterior and Anterior Aspects of the
Inferior Extremity

. 851
465. Diagram of the Lumbar and Sacral Plexuses
Modified from Paterson 855
466. A Dissection of the Lumbar and Sacral Plexuses, from behind.
467. A Dissection of the Nerves in the Gluteal Region.
. 856
857
468. Distribution of the Musculo-cutaneous and Anterior Tibial Nerves on the Anterior
Aspect of the Leg, and on the Dorsum of the Foot
. 860
469. Superficial Nerves in the Sole of the Foot
Ellis
862
470. The Cervical Portion of the Sympathetic, and the Distribution of the Pneumo-
Hirschfeld and Leveillé
gastric Nerve, viewed from behind
Krause 866
471. Lumbar Portion of the Gangliated Cord, with the Solar and Hypogastric
Plexuses
472. View of the Eyeball, etc., obtained on drawing the Lids forcibly apart
After Merkel, slightly modified
473. Left Fundus Oculi, as seen by direct Ophthalmoscopic Method After Fuchs 878
474. Diagrammatic View of the Insertions of the Ocular Muscles
475. Equatorial Section of Eyeball: Anterior Segment viewed from behind.
After Merkel 879
880
Henle 872
876
After Merkel

xxvi
LIST OF ILLUSTRATIONS
FIG.
476. Diagrammatic Horizontal Section of Eyeball and Orbit
PAGE
883
885
•
•
Leber 887
After Fuchs, much modified
477. Semi-diagrammatic Horizontal Section through Eyeball and Optic Nerve
After Elfinger, reduced and altered
478. Diagrammatic Representation of the Blood-vessels of the Eyeball
479. Surface of Choroid and Iris exposed by removal of Sclerotic and Cornea,
showing Distribution of Blood-vessels and Nerves
•
After Zinn 888
480. The Lymphatics of the Eyeball
Diagrammatic, after Fuchs 889
481. Left Eyeball seen in its Normal Position in the Orbit, with View of the Ocular
Muscles
After Merkel, modified 890
482. Section through Contents of Right Orbit, 8-11 mm. behind the Eyeball, viewed
from behind
After Lange 891
483. Diagrammatic Representation of Origins of Ocular Muscles at the Apex of
the Right Orbit.
After Schwalbe, slightly altered
484. View of Left Orbit from above, showing the Ocular Muscles
From Hirschfeld and Leveillé
485. Vertical Section through the Eyeball and Orbit in the direction of the Orbital
Axis, with closed Eyelids .
Semi-diagrammatic, after Schwalbe, modified to show fascia
486. Horizontal Section through Left Orbit, viewed from above
After Von Gerlach, to show check ligaments etc.
487. Transverse Section through Optic Nerve, showing the Relations of its Sheaths
and Connective-tissue Framework
892
894
•
895
896
898
. 898
•
899
After Lange 900
488. Longitudinal Section through Termination of Optic Nerve
489. The Blood-vessels of the Left Orbit, viewed from above
490. Section through Contents of Right Orbit, 1-2 mm. in front of the Optic
Foramen, viewed from behind
491. Vertical Transverse Section through Upper Eyelid. After Waldeyer and Fuchs
492. Lachrymal Apparatus
493. External View of the Left Auricle
902
After Schwalbe 905
907
•
908
494. Section through the Orifice of the Right External Auditory Meatus
495. External and Internal Surface of the Cartilage of the Right Pinna and its
Muscles, etc.
496. Section of the Middle and External Ear
497. External View of the Left Membrana Tympani
498. Internal View of the Right Membrana Tympani
499. Section of the Tympanum, etc.
500. Osseous Labyrinth of the Right Side
501. Interior of the Osseous Labyrinth of the Left Side
·
909
. 910
911
. 912
914
Modified from Soemmerring, enlarged 916
Modified from Soemmerring, enlarged
917
502. Interior of the Osseous Cochlea.
503. Section of the Osseous Cochlea
917
918
•
504. Membranous Labyrinth (magnified), with Nerves
505. Enlarged Diagrammatic View of Membranous Labyrinth
506. Enlarged View of Longitudinal Section of the First Turn of the Cochlea,
showing the Positions and Boundaries of the Three Scale
Modified from Breschet 919
919
920
507. Dorsum of the Tongue
508. The Foetal Tongue
509. Under Surface of the Tongue with Muscles
510. Transverse Section through the Left Half of the Tongue (magnified)
922
923
923
924
Middlesex Hospital Museum
511. Side View of the Tongue, with its Muscles
512. Side View of the Nose, showing its Cartilages, etc.
513. Anterior View of the Nose, showing its Cartilages, etc.
514. Under View of the Nose, showing its Cartilages, etc.
515. Section showing Bony and Cartilaginous Septum
516. Muscles of the Nose
•
924
926
927
928
.929
517. Oblique Section passing through the Nasal Fossæ, just in front of the Posterior
Nares, seen from behind
After Bourgery 930
931

LIST OF ILLUSTRATIONS
xxvii
FIG.
518. Section of the Nose, showing the Turbinal Bones and Meatuses, with the Open-
ings in dotted outline
519. Transverse Section passing through the Nasal Fossæ and Antra at the posterior
extremity of the Middle Turbinal Bone.
520. Nerves of the Nasal Cavity
PAGE
932
932
•

933
521. Anterior View of the Thorax, with Outlines of the Diaphragm and Lungs .936
522. Superior View of a Section of the Thorax, passing through the Sternum
immediately below the First Costo-sternal Articulation, through the Trachea
at its Division, and through Body of the Fourth Thoracic Vertebra. Braune 937
523. Front View of the Cartilages of the Larynx Modified from Bourgery and Jacob 939
524. Side View of the Cartilages of the Larynx. Modified from Bourgery and Jacob
525. Front View of the Cricoid and Arytenoid Cartilages
Modified from Bourgery and Jacob
526. Back View of the Cricoid and Arytenoid Cartilages
·
Modified from Bourgery and Jacob
527. Superior View of the Cartilages of the Larynx
528. Side View of the Muscles and Ligaments of the Larynx
529. Scheme of the Rima, showing Action of Crico-arytenoideus Posticus
940
942
942
943
944
945
Modified from Stirling
530. Posterior View of Thyroid Cartilage, with Epiglottis.
531. Scheme showing Action of Thyro-Arytenoid.
946
946
.
532. Scheme showing Action of Arytenoideus
947
533. View of the Interior of Larynx as seen during Inspiration
948
534. View of the Interior of the Larynx as seen during Vocalisation
535. Nerves of the Larynx (posterior view)
948
.
949
536. Anterior View of Larynx, with Trachea and Bronchi Modified from Bourgery 951
537. View of the Thyroid Body.
953
538. Thyroid Body, with Middle Lobe and Levator Muscle.
954
539. The Suspensory Ligaments of the Thyroid Body
After Berry 955
540. Thymus Gland in a Child at Birth
956
541. Thymus Gland in a Child at the Age of Two Years
957
€959
·
959
960
.
542. Anterior View of the Foetal Heart, Vessels, and Lungs.
543. Anterior View of the Thorax with Chest Wall removed, showing the Lungs
Modified from Bourgery
544. Posterior View of the Thorax with Chest Wall removed, showing the Lungs
545. Anterior View of the Lungs: Pericardium
546. Anterior View of the Heart with the Larger Vessels
Modified from Bourgery
Modified from Bourgery 961
964
Royal College of Surgeons Museum
547. Showing the Position of the Heart and its Valves in relation to the Chest Walls 965
Reduced from Hensman and Fisher
548. Transverse Section passing through the Auricles of the Heart, showing the
Auriculo-ventricular Orifices and the Semilunar Valves of the Pulmonary
Artery and Aorta (seen from above)
966
549. Anterior View of the Right Chambers of the Heart, with the Great Vessels.. 967
550. Transverse Section through the Heart near its Apex, showing the relative
thickness of its Muscular Walls, the bulging of the Septum towards the Right
Ventricle, and the Shape of the Cavities
551. Interior View of the Aortic Semilunar Valves
•
968
969
553. Posterior View of the Left Chambers of the Heart with the Great Vessels and
the Coronary Sinus laid open
·
554. Showing the Position of the Heart and its Valves to the Chest Wall.
552. View of the Auricular Cavities from below (the Transverse Section passing
above their middle).
970
.
971
973
Reduced from Hensman and Fisher
555. Anterior View of the Heart, showing its Arteries and Veins.
556. Posterior View of the Heart, showing its Arteries and Veins
557. Anterior View of a Foetus. The Heart, Vessels, and Chief Organs displayed,
974
975
with the Placenta and Umbilical Cord
976
xxviii
LIST OF ILLUSTRATIONS
FIG.
558. Anterior View of the Heart and Great Vessels of Foetus, the Anterior Chest
Wall being removed and the Heart Sac opened
559. The Salivary Glands
560. Section showing the Posterior Wall of the Pharynx, with the Pharyngeal Bursa,
Fauces, etc.
PAGE
. 978
983
. 986
561. Transverse Section of the Peritoneal Sac at about the Level of the Umbilicus. 989
562. Transverse Section of the Abdomen at the Level of the Foramen of Winslow. 990
563. Diagram to show the Peritoneum as seen in a Vertical Section. Allen Thomson 991
564. Diagram to show the Peritoneum as seen in Vertical Section Allen Thomson 993
565. The Viscera as seen on fully opening the Abdomen, without Disarrangement
of the Internal Parts
566. Posterior Surface of the Stomach
567. Anterior Surface of the Stomach
568. Muscular Coat of the Stomach
569. Muscular Coat of the Stomach
570. The Duodenum from the front
571. The Duodenum from behind
572. The Fossa Duodeno-jejunalis
.After Sarazin 995
996
997
Luschka 998
Luschka 999
. 1001
. 1001
Treves 1002
573. Portion of the Small Intestine, laid open to show the Valvula Conniventes
Brinton 1004
574. Vessels of the Small Intestine
575. The Four Types of Cæcum
576. Section of the Ascending Colon
. 1005
Treves 1006
Allen Thomson 1008
577. View of the Deeper Abdominal Viscera
578. The Viscera of the Fœtus.
579. The Superior Surface of the Liver.
580. The Inferior Surface of the Liver
581. The Posterior Surface of the Liver.
582. Relation of the Abdominal Viscera to the Parietes
583. Relation of the Abdominal Viscera to the Parietes
584. Relation of Structures at and below the Transverse Fissure
585. Structure of a Portal Canal.
586. Abdominal Viscera, from behind
587. The Pancreas and its Duct
588. Outer Aspect of the Spleen.
Rüdinger 1010
.Rüdinger 1013
1014
. 1015
.1016
Treves 1017
Treves 1018
Thane 1020
Quain 1021
Rüdinger 1022
. 1024
. 1025
589. Inner Aspect of the Spleen
590. Transverse Section of the Body at the Lower Part of the Epigastric Region
591. View of the Spleen, etc., from behind
592. Diagram of the Primitive Alimentary Canal
593. Diagram of the Primitive Alimentary Canal.
594. Alimentary Canal of Salamandra maculosa
595. Alimentary Canal of Salamandra maculosa.
596. Alimentary Canal of Cholapus Hoffmanni
597. Diagram to show the Rotation of the Intestinal Canal.
598. Diagram to show the Relation of the Peritoneum to the Duodenum.
. 1026
Rüdinger 1026
Rüdinger 1027
599. Diagram to show the Lines along which the Peritoneum leaves the Wall of the
Abdomen to invest the Viscera
600. Diagram to show the Formation of the Great Omentum
601. Great Omentum in Macropus penicillatus
. 1030
. 1030
. 1031
•
1032
1033
. 1034
. 1035
Cunningham 1037
1038
1038
•
602. Formation of Great Omentum as seen in Vertical Section
603. Relation of Great Omentum to Transverse Colon
.1039
1040
604. Transverse Section of the Abdomen at the Level of the Foramen of Winslow
1040
605. Intestine of Macropus penicillatus
1041
606. Duodenal Fold of Macropus penicillatus
. 1041
607. Postero-internal Aspect of Left Kidney
608. Diagram showing Relation of Kidney to Capsule
. 1042
1043
609. Section of Kidney, showing the Sinus
After Henle 1044
610. Diagram of Relations of the Posterior Surface of the Kidney
1044
.
LIST OF ILLUSTRATIONS
xxix
FIG.
611. The Abdominal Viscera, seen from behind
PAGE

From the model of His 1045
•
612. Diagram showing Anterior Relations of Kidneys and Suprarenal Bodies . 1046
613. Horizontal Section of Kidney, showing the Sinus
614. Scheme of Tubules and Vessels of the Kidney
•
1048
After Macalister 1049
615. Diagram showing Relations of the Kidneys and Suprarenal Bodies
616. Upper Portion of Duct
1051
1.After Henle 1052
617. Median Sagittal Section of the Male Pelvis St. Thomas's Hospital Museum 1054
618. The Posterior Wall of the Bladder
619. Section of the Female Pelvis.
620. Semi-diagrammatic Section of the Male Pelvis.
621. Horizontal Section of the Scrotum and Tetsicle (diagrammatic)
622. The Left Testicle, with Vessels and Duct.
623. Diagram of the Testicular Tubules
624. Vasa Deferentia and Vesiculæ Seminales
625. Vas Deferens and Vesicula Seminalis dissected
626. Section of the Spermatic Cord.
627. Transverse Section through the Body of the Penis
628. Transverse Section of the Penis through the base of the Glans.
629. The Male Perinæum
.
Modified from Hirschfeld
After Henle 1056
After Henle 1057
. 1059
.. 1061
After Sappey 1062
. . 1064
After Sappey 1066
After Sappey 1067
After Henle 1068
.1069
. 1070
and Leveillé 1071
630. The Male Urethra, cleft dorsally to show Ventral Mucous Wall
631. The External Genitals of the Female
632. Diagrammatic Representation of the Perineal Structures in the Female.
633. Section of the Female Pelvis.
634. Horizontal Section of Vagina and adjacent Structures
635. The Female Organs of Generation.
636. The Posterior Surface of the Uterus
637. Frontal Section of the Virgin Uterus
638. Sagittal Section of the Virgin Uterus.
. 1073
After Sappey 1076
. 1077
After Henle 1078
After Henle 1080
Modified from Sappey 1082
639. The Broad Ligament and its Contents, seen from the Front.
640. Diagrammatic Section of the Broad Ligament.
After Sappey 1082
After Sappey 1083
•
After Sappey 1083
After Sappey 1085
. 1086
. 1087
After Sappey 1089
641. Section of the Pelvis showing the Ligaments of the Uterus.
642. The Broad Ligament and its Contents, seen from the Front
643. Diagram of the Arteries and Lymphatics of the Female Generative Organs
644. Diagram of the Primitive Genito-urinary Organs before Differentiation of
Sex
645. Development of the Urino-generative Organs, Female Type
646. Development of the Urino-generative Organs, Male Type

647. The Male Perinæum
648. Diagram of the Pelvic Fascia
649. Muscles of the Floor of the Pelvis.
. 1091
•
After Henle 1093
After Henle 1094
After Henle 1095
Modified from Hirschfeld
and Leveillé 1097
1098
•
. 1099
650. Diagram showing Lines of Attachment of the Fascia and Muscles of the Pelvis 1100
651. Muscles of the Floor of the Pelvis
1. 1101
•
•
€1102
652. Sagittal Section through the Perinæal Ledge and Ischio-rectal Fossa to the left
of the Middle Line (diagrammatic)
653. Section showing the Ischio-rectal Fossa in its relations to the Pelvic Viscera 1103
654. Diagram of the Superficial and Deep Triangular Ligaments
655. Vertical Frontal Section of the Pelvis, showing Fascia Modified from Braune 1105
656. Diagrammatic Representation of the Perineal Structures in the Female . . 1107
657. The Female Mamma during Lactation
658. Development of the Mamma of the Female Embryo
659. The Skull in Sagittal Section
660. The Cranium at Birth
·
661. The Skull (norma lateralis)
662. Drawing of a Cast of the Head of an Adult Male.
663. Section through the Scalp, Skull, and Dura Mater
664. The Course of the Occipital Artery
665. Scheme of the Facial Artery
.1104
After Luschka 1108
After Langer 1110
. 1112
. 1112
1113
Cunningham 1114
Tillaux 1115
1. 1117
. 1118
666. Vertical Transverse Section through Upper Eyelid After Waldeyer and Fuchs 1119
667. The Lachrymal Apparatus and Nasal Duct
Bellamy 1120.
XXX
LIST OF ILLUSTRATIONS
FIG.
PAGE
668. Side of the Face and Mouth Cavity, showing the three Salivary Glands
669. Section of the Skull and Brain in the Median Plane
. 1121
Braune 1122
670. Section of the Nose, showing the Turbinal Bones and Meatuses, with the Open-
ings in dotted outline
671. Section showing Bony and Cartilaginous Septum
672. Thymus Gland in a Child at Birth
673. Anterior and Lateral Cervical Muscles
. 1123
1123
. 1125
1. 1126
674. The Internal Carotid Artery, and Deep Branches of the External Carotid
Artery
Royal College of Surgeons Museum 1127
675. The Common Carotid, the External and Internal Carotid, and the Subclavian
Arteries of the Right Side and their Branches
. 1128
St. Bartholomew's Hospital Museum
676. The Subclavian Vessels .
Royal College of Surgeons Museum 1129
677. Region of the Third Part of the Subclavian Artery.
Bellamy 1130
678. The Collateral Circulation after Ligature of the Common Carotid and Subclavian
Arteries.
679. Diagram of the Layers of the Deep Cervical Fascia in an Antero-posterior
Section opposite to the Sternum.
. 1131
Tillaux 1132
680. Diagram of the Arrangement of the Deep Cervical Fascia, the section passing
through the Clavicle
Tillaux 1132
Braune 1133
681. Section of Neck through the Sixth Cervical Vertebra
682. The Arch of the Aorta, with the Pulmonary Artery and Chief Branches of the
Aorta
St. Bartholomew's Hospital Museum 1135
683. Section of the Sixth Left Intercostal Space, at the Junction of the Anterior and
Posterior Thirds
684. Anterior View of the Lungs: Pericardium
Tillaux 1136
Holden 1138
Modified from Bourgery 1137
685. Outline of the Heart, its Valves, and the Lungs (shaded)
686. Diagram of the Relations of the Thoracic Viscera to the Walls of the Chest
Bellamy 1139
1140
•
. 1142
687. Anterior View of Foetal Heart, Vessels, and Lungs
688. The Obliquus Externus and Fascia Lata
689. The Pectoralis Minor, Obliquus Internus, Pyramidalis, and Rectus Abdominis 1143
690. The Viscera as seen on fully opening the Abdomen without Disarrangement of
the Internal Parts
After Sarazin 1145
691. Section of Abdomen between the Third and Fourth Lumbar Vertebræ Braune 1146
692. Diagram showing Relation of Kidney to Capsule
. 1147
693. Transverse Section of the Abdomen through the Kidneys and Pancreas, at the
level of the First Lumbar Vertebra
Braune 1148
694. The Abdominal Aorta and Inferior Vena Cava
1149
•
695. The Male Perinæum
696. The Male Perinæum
697. The Arteries of the Perinæum
Modified from Hirschfeld and Leveillé 1150
Roser 1151
. 1152
Braune 1153

698. Sagittal Section of the Male Pelvis in the Mesial Line
699. Section showing the Ischio-rectal Fossa in its Relations to the Pelvic Viscera. 1153
700. Scheme of the Pudic Artery and its Branches
701. The Muscles attached to the Pubes
702. Diagram of the Pelvic Fascia
1154
•
Royal College of Surgeons Museum 1154
.
1155
703. External Genitals of the Virgin, with Diaphragmatic Hymen After Sappey 1156
704. Diagrammatic Representation of the Perinæal Structures in the Female .
. 1157
705. Section of the Female Pelvis
After Henle 1158
706. The Parts involved in Inguinal Hernia. Royal College of Surgeons Museum 1160
707. Dissection of the Lower Part of the Abdominal Wall from within, the
•
Peritoneum having been removed
708. Vertical Section of Pelvis, through the Heads of the Thigh Bones
709. Transversalis Abdominis and Sheath of Rectus
710. Superficial Dissection of the Inguinal and Femoral Regions
Wood 1162
Blandin 1163
1164
Wood 1165
Blandin 1167
After Gray 1168
711. Section through the Crural Arch and Sheath of the Femoral Vessels
712. Irregularities of the Obturator Artery
713. The First Layer of the Muscles of the Back.
•
1171
LIST OF ILLUSTRATIONS
xxxi
FIG.
714. The Levator Anguli Scapulæ and Rhomboidei
PAGE
. 1172

715. Diagram and Table showing the Approximate Relation to Spinal Nerves of the
various Motor, Sensory, and Reflex Functions of the Spinal Cord. Gowers 1173
716. Chief Arterial Anastomoses of the Scapula. Royal College of Surgeons Museum 1174
717. Arrangement of Lumbar Aponeurosis at Level of Third Lumbar Vertebra
718. Relation of the Abdominal Viscera to the Anterior Parietes
719. Relation of the Abdominal Viscera to the Posterior Parietes.
720. Abdominal Viscera, seen from behind
•
. 1175
Treves 1176
Treves 1177
Rüdinger 1178
721. The Superior and Inferior Vena Cave, the Innominate Veins, and the Azygos
Veins.
722. View of the Spleen, etc. from behind.
. 1179
Rüdinger 1180
723. Transverse Section through the Right Shoulder Joint, showing the Structures
in contact with it
724. The Pectoralis Major and Deltoid
725. Superficial View of the Front of the Upper Arm
726. The Brachial Artery
•
Braune 1181
. 1181
. 1182
Royal College of Surgeons Museum 1183
727. Section through the Middle of the Right Upper Arm
728. The Lower Part of the Axillary, the Brachial, and the Radial and Ulnar
Arteries
Heath 1184
Royal College of Surgeons Museum 1185
729. Back View of the Scapular Muscles and Triceps
730. Deep View of the Front of the Upper Arm
731. Vertical Section of the Elbow
732. Longitudinal Section of the Elbow Joint
733. Bend of the Elbow
. 1186
. 1187
Braune 1188
Braune 1189
Blandin 1189
734. The Bend of the Elbow with the Superficial Veins
1090
Saint Bartholomew's Hospital Museum
735. The Brachial Artery at the Bend of the Elbow
736. The Arteries of the Forearm with the Deep Palmar Arch.
737. Front of the Forearm: First Layer of Muscles
. 1191

1192
1193
738. Front of the Forearm: Second Layer of Muscles
739. Section through the Middle of the Right Forearm.
740. Superficial Nerves of the Forearm
1194
Heath 1195
1196
.
741. Distribution of Cutaneous Nerves on the Anterior and Posterior Aspects of the
Superior Extremity
742. Superficial Veins and Lymphatics of the Forearm and Arm
743. Relation of the Palmar Arches to the Folds of the Palm

744. Anastomoses and Distribution of the Arteries of the Hand
745. The Deep Layer of the Back of the Forearm
746. The Superficial Muscles of the Palm of the Hand
747. Muscles of the Radial Side and the Back of the Forearm
748. The Deeper Muscles of the Palm of the Hand
.
•
. 1197
1198
Tillaux 1199
•
1200
.
1201
. 1202
. 1203
•
1204
749. Section through Region of Wrist, a little above the Joint. Right side, upper
half of the Section
. Tillaux 1205
750. Transverse Section of the Wrist, through the middle of the Pisiform Bone. 1205
751. Diagram of the Great Palmar Bursa .
•
1206
.
752. Section of Carpus, through Unciform Bone
753. Horizonal Section of the Hand through the Carpo-metacarpal Joints
Bellamy after Henle 1207
1207
.
Bellamy after Henle
754. Tendons upon the Dorsum of the Hand
1208
•
1209
755. Diagram of a Vertical Section through the Middle of the Hand
756. Transverse Section of the Hip Joint and its Relations.
757. Muscles of the Front of the Thigh
•
Braune 1211
1212
Heath 1213
Hirschfeld and Leveillé 1214
758. Section of the Right Thigh at the Apex of Scarpa's Triangle
759. Superficial Dissection of the Front of the Thigh
760. Anterior Crural and Obturator Nerves
Ellis 1215
761. Side View of the Pelvis and Upper Third of Thigh, with the External Iliac,
Internal Iliac, and Femoral Arteries and their Branches
1216
St. Bartholomew's Hospital Museum
762. The Deep Muscles of the Front of the Thigh
1217
xxxii
LIST OF ILLUSTRATIONS
FIG.
763. Superficial Muscles of the Back of the Thigh and Leg
•
764. Section through the Hip and Gluteal Region
765. The Gluteal Region, with the Gluteal, Sciatic, and Pudic Arteries
PAGE
1218
. 1219
1220
St. Bartholomew's Hospital Museum
Royal College of Surgeons Museum 1221
1221
.
1223
766. Deep Dissection of the Gluteal Region
767. Horizontal Section of the Knee Joint
768. The Deep Muscles of the Back of the Thigh
769. Vertical Section through the Knee Joint in the Antero-posterior Direction . . 1224
770. The External Rotators and the Hamstring Muscles
1225
771. Side View of the Popliteal Artery.
772. Deep View of the Popliteal Space
773. The Popliteal, the Posterior Tibial, and the Peroneal Arteries
774. The Anterior Tibial Artery, the Dorsal Artery of the Foot, and Anterior
Peroneal Artery, and their Branches
Royal College of Surgeons Museum 1226
Hirschfeld and Leveillé 1227
•
775. Relations of the Popliteal Artery to Bones and Muscles
776. Section of the Right Leg in the Upper Third
777. Branches of the External Popliteal Nerve
778. The Muscles of the Front of the Leg.
1228
1229
1230
•
Heath 1231
1232
•
779. Transverse Section through the Lower Third of the Left Leg, immediately above
the Ankle Joint
•
780. Relations of Parts behind the Inner Malleolus
781. The Deep Muscles of the Back of the Leg
782. Articulations of the Foot, Dorsal Aspect
783. Vertical Section through the Cuneiform and Cuboid Bones
784. Superficial Nerves in the Sole of the Foot .
785. The Plantar Arteries (Deep)
786. Longitudinal Section of Foot
•
1234
Braune 1235
Heath 1235
1236
Bellamy 1239
•
1239
Ellis 1240
Royal College of Surgeons Museum 1241
Braune 1242
Ellis (of Gloucester) 1243
787. The Arch in the Ordinary Position of Standing
788. The Effect of Muscular Action in throwing up the Arch Ellis (of Gloucester) 1243
789. Fourth Layer of the Muscles of the Sole
790. The Superficial Veins and Lymphatics of the Lower Limb
. 1244
1245
•
791. Distribution of Cutaneous Nerves on the Posterior and Anterior Aspects of the
Inferior Extremity
1246

Additional List of Errata discovered since this work was published
Page 55, fig. 64, for INTERIOR NASAL SPINE read ANTERIOR NASAL SPINE
29
69, line 3 from bottom, for stylo-maxillary read stylo-mandibular
99
87, fig. 92, for INTERIOR NASAL SPINE read ANTERIOR NASAL SPINE
29
""
دو
176, 17, after calcaneum read and external cuneiform
,
29
22
""
""
145, line 6 from bottom, for third palmar interosseous read second palmar interosseous
289, fig. 257, for LIGAMENTS read LIGAMENTS OF THE SOLE OF THE FOOT
323, line 28, for posterior aspect now becomes external read anterior aspect now becomes external
437, at upper portion of fig. 305, for Serratus posticus inferior read Serratus posticus superior
471, fig. 313, at end of pointer read Interarticular fibro-cartilage
484, line 19, for pneumogastric nerve read phrenic nerve
609, fig. 370A, for Transverse perineal vessels and nerve read Inferior haemorrhoidal vessels and nerve
743, line 1, for macroscopic read microscopic
29
""
821, lines 3 and 5 from bottom, for stylo-hyoid read stylo-glossus
""
""
849, line 6, for inferior oblique read internal oblique
861, 6, for anterior interosseous read posterior interosseous
863,
دو
11 from bottom, for third and fourth toes read fourth and fifth toes
911,
""
99
3, for notch of Rivini read notch of Rivinus
,, 961,,, 9, for bronchus, artery, and vein read vein, artery, and bronchus
,,1136,,, 12, for thyroid gland read th ymus gland
وو وو
دو
22, for last thoracic nerve read first thoracic ner ve
29
1152, fig. 697, for Transverse perineal vessels and nerve read Inferior hæmorrhoidal vessels and nerve
,, 1179, last line, for superior vena cava read inferior vena cava
,, 1194, line 3, for higher level read lower level
,, 1196, fig. 740, for Flexor carpi radialis read Flexor carpi ulnaris
دو
1233, line 4, for of the head of the fibula read of the tibia and the head of the fibula
SECTION I.
OSTEOLOGY
BY J. BLAND SUTTON, F.R.C.S.ENG.
ASSISTANT-SURGEON TO THE MIDDLESEX HOSPITAL, LONDON
THE SKELETON

THE skeleton contains 206 distinct bones. They are arranged by anatomists in
two sets:-the bones of the trunk and the bones of the limbs. The skeleton
of the trunk is made up of the skull, which contains twenty-nine bones exclusive
of the teeth; the vertebral column consisting of twenty-six separate bones;
twenty-four ribs, and the sternum. The skeleton of the upper limbs comprises
sixty-four bones; and that of the lower limb, including the patella, sixty-two.
In
Several of the skull bones are compound, that is, in the immature skeleton they
consist of separate elements which ultimately unite to form a single bone.
order to comprehend the nature of such bones, it is necessary to examine them
in the various stages through which they pass in the embryo and child. Thus the
student, anxious to convince himself of Man's place in nature, studies carefully the
development and ossification of bones, and compares them with the bones of other
Vertebrata. He then finds that many elements which make a compound bone are
osteological units for the Comparative Anatomist.
Comparisons of this nature constitute the science of Morphology, one of the
most fascinating departments of Biology.
It is the duty of the student to follow the descriptions with the actual bones in
his hand. He should also remember that many variations occur in the outlines
and markings of bones. Hence the various types described and figured represent
the average of a large number of bones examined. It is very rare to meet with
bones which accurately correspond to the description in every detail.
In order to appreciate the morphology of the skeleton, the osteogenesis or mode
of development of bones must be studied as well as their topography or position.
Some bones arise by ossification in membrane, others in cartilage. In the early
embryo, many portions of the skeleton are represented by cartilage which becomes
infiltrated by lime salts-calcification. This earthy material is taken up and
redeposited in a regular manner--ossification. Portions of the original cartilage
persist at the articular ends of bones, and, in young bones, at the epiphysial lines.
Long bones increase in length at the epiphysial cartilages, and increase in
thickness by ossification of the deeper layers of the investing membrane or
periosteum. These processes-intercartilaginous and intermembranous ossifica-
tion-proceed concurrently in the limb-bones of a young and growing mammal.
There is no bone in the human skeleton which, though pre-formed in cartilage,
is perfected in this tissue. The ossification is completed in membrane. On the
B
2
THE SKELETON
other hand, there are numerous instances in the skull, of bones the ossification of
which begins in, and is perfected by, the intermembranous method. Ossification in
a few instances commences in membrane, but later invades tracts of cartilage;
occasionally the process begins in perichondrium and remains restricted to it, never
invading the underlying cartilage, which gradually disappears as the result of
continued pressure exerted upon it by the growing bone. The vomer and nasal
bones are the best examples of this mode of development.
A CLASSIFIED LIST OF THE BONES TO SHOW THEIR MODE OF
DEVELOPMENT
1. All the limb-bones and those of the vertebral column are pre-formed in carti-
lage and perfected in membrane, with the exception of the clavicles. These begin
in membrane, proceed in cartilage, and are finally perfected in membrane.
2. The Skull.
Parietals.
Frontal.
Squamosals.
Maxillæ.
Malars.
Palates.
Nasals.
Sphenoid.
Petrosals.
Mallei.
Stapes.
Hyoid.
Inferior turbinals.
MEMBRANE-BONES
Interparietal portion of occipital.
Wormian bones and the epipterics.
Tympanics.
Mandible (except part near the
symphysis).
Lachrymals.
Vomer.
CARTILAGE BONES
Occipital (except interparietal portion).
Ethmoid.
Incudes.
Styloid processes.
Symphysial portion of the mandible.
Internal pterygoid plate.
Many of the skull bones are composite, that is, they consist of two or more
elements which remain separate in other vertebrates. To this group belong :-
The Occipital.
Temporals.
Ethmoid.
Maxillæ.
Hyoid.
Sphenoid.
Frontal.
Malars.
Mandible.
The details of the development and ossification of each bone are added to the
description.
The limb-bones differ in several important particulars from those of the skull.
Some of the long bones have many centres of ossification, but the centres are of
very different morphological value to those of the skull. Speaking generally, it is
only the primary nuclei that have any especial value for the morphologist. The
primary nucleus of a long bone appears before birth. In only three instances does
a secondary centre appear before birth; e.g. the condyles of the femur, the head of
the tibia, and occasionally in the head of the humerus. Many primary ossific nuclei
appear after birth; for example, those for the carpal bones, the cuneiform and
scaphoid bones of the foot, the coracoid, and the third, fourth and fifth pieces
of the sternum.
When a bone ossifies from one nucleus only, this nucleus may appear before
or after birth. Examples: the astragalus at the seventh month of embryonic
life, and the trapezoid at the eighth year. When a bone possesses one or more

OSSIFICATION-RULES OF EPIPHYSES
3
secondary centres, the primary nucleus, as a rule, appears early. Examples: the
femur, humerus, phalanges, and the calcaneum.
Secondary centres which remain for a time distinct from the main portion of a
bone are termed epiphyses. An epiphysis may arise from a single nucleus, as is
the case with the lower end of the femur; or from several, as at the upper end of
the humerus. Prominences about the ends of long bones may be capped by separate
epiphyses, as is the case at the upper end of the femur. Epiphyses, though of
no morphological value, seem to follow certain rules, thus :-

FIG. 1.—THE TIBIA AND FIBULA IN SECTION TO SHOW THE EPIPHYSES.

EPIPHYSIS
-CENTRE OF OSSIFICATION OF EPIPHYSIS
EPIPHYSIAL LINE
SHAFT OF FIBULA
SHAFT OF TIBIA IN SECTION
EPIPHYSIS OF TIBIA
EPIPHYSIS OF FIBULA
1. Those epiphyses which appear last are the first to unite with the shaft.
Exception.-The distal epiphysis of the fibula is visible three years before the
proximal, but fuses with the shaft much earlier than it. It should be remembered
that the proximal end of the fibula in man and many mammals is vestigial.
2. The epiphysis towards which the nutrient artery is directed unites first with
the shaft.
B2
4
THE SKELETON
3. When a bone has only one epiphysis, the nutrient artery is directed towards
the extremity which has no epiphysis.
4. The centres of ossification appear earliest for those epiphyses which bear the
largest relative proportion to the shafts of the bones to which they belong.
5. When an epiphysis ossifies from more than one centre, the various nuclei
coalesce before the shaft and epiphysis consolidate.
On section the shaft of a fœtal long bone is found occupied with red marrow
lodged in bony cells which do not present any definite arrangement. In an adult,
the central portion of the shaft of a long bone is filled with fat, or marrow, held
together by a delicate reticulum of connective tissue; the space containing the
marrow is the medullary cavity. The expanded ends of the bone contain a network
of cancellous tissue, the spaces being filled with red marrow. This cancellous tissue
differs from that of the foetal bone in that it is arranged in a definite manner
according to the direction of pressure and tension exerted by muscles. Pressure
lines are well shown in the vertebræ. In a vertical section through the centrum of
a vertebra the fibres of the cancellous tissue are seen to be arranged vertically and
horizontally; the vertical fibres are curved with their concavities directed towards
the centre of the bone. The horizontal fibres are slightly curved parallel with the
FIG. 2.-A VERTEBRAL CENTRUM IN SECTION TO SHOW THE PRESSURE CURVES.

upper and lower surfaces, with their convexities towards the centre of the bone.
They are not so defined as the vertical set. (Wagstaffe.)
The arrangement of the cancelli in individual bones is a consequence of the
mechanical conditions to which the bone is subject. This is well illustrated in the
femur. In the upper end of this bone the cancellous tissue is arranged in
divergent curves. One set springs from the inner wall and spreads into the greater
trochanter; a second series of curves crosses this and forms a set of Gothic arches,
and is continued into the neck and head; a third set springs from the lower thick
wall of the neck and spreads into the upper part of the head, and ends perpen-
dicularly in the articular surface mainly along the lines of greatest pressure. A
nearly vertical plane of compact tissue projects into the neck of the bone from the
inferior cervical tubercle towards the great trochanter. This is placed in the
line through which the weight of the body falls, and adds to the stability of the
neck of the bone: it is said to be liable to absorption in old age. In the lower
end of the bone the vertical and horizontal fibres are so disposed as to form a
rectangular meshwork.
The plan of construction exhibited by the femur is the most complex in the
skeleton, but the principles involved are the same in all bones. An interesting
disposition of these curves is exhibited in the head of the humerus. The pressure
curves radiate in two directions: one set at right angles to the articular surface of
the head of the bone; the other at right angles to the greater tuberosity. The last
set, like those in the trochanter, are the result of tension exerted by the muscles
attached to these prominences.
The shafts of long bones at the time of birth are mainly cylindrical and free
from ridges. The majority of the lines and ridges so conspicuous on the shafts of


THE SPINE
5
long bones in adults are due to the ossification of muscle-attachments. The more
developed the muscles, the larger the ridges become.
The surfaces of bones are variously modified by environing conditions. Pressure
at the extremities causes enlargement, and movement renders them smooth. The
two causes combined produce an articular surface. When rounded and supported

FIG. 3.-A DIAGRAM TO SHOW THE
PRESSURE AND TENSION CURVES OF
THE FEMUR. (After Wagstaffe.)
FIG. 4.-A DIAGRAM SHOWING
V PRESSURE AND TENSION CURVES
IN THE HEAD OF THE HUMERUS.
(After Wagstaffe.)
upon a constricted portion of bone, an articular surface is termed a head, sometimes
a condyle; when depressed, a glenoid fossa. Blunt, non-articular processes are
called tuberosities; smaller ones, tubercles; sharp projections, spines. Slightly
elevated ridges of bones are crests; when narrow and pronounced, lines and
borders. A shallow depression is a fossa; when narrow and deep, a groove; a
perforation is usually called a foramen. The majority of terms-such as canal,
spine, notch, sulcus, and the like--are so obvious as to render explanation needless.
THE SPINE
The spine (vertebral column) consists of thirty-three superimposed bones
termed vertebræ. Of these the upper twenty-four remain separate throughout
life and form three groups. The first seven are called cervical, the succeeding
twelve thoracic (dorsal), and the last five lumbar. In adult life the last nine
vertebræ ankylose to form two composite bones named the sacrum and the coccyx.
The sacrum is formed by the fusion of five vertebræ from the twenty-fifth to the
twenty-ninth inclusive; the four terminal are vestigial, and form the coccyx. In
order to gain a general notion of the characters of a vertebra, it is desirable to select
a bone from the middle of the thoracic series.
6
THE SKELETON
A vertebra presents the following parts: The body or centrum is a solid disc
of bone slightly concave on its superior and inferior aspects, and wider transversely
than antero-posteriorly. The upper and lower surfaces are rough for intervertebral
discs, and the margins are slightly lipped. The circumference of the body is, in
front, concave vertically, but convex from side to side; posteriorly it is excavated,
and presents foramina for the escape of veins from the cancellous tissue. On the
FIG. 5.-A THORACIC VERTEBRA. (Side view.)
SUPERIOR ARTICULAR PROCESS-
FACET FOR TUBERCLE OF RIB-
TRANSVERSE PROCESS
DEMI-FACET FOR HEAD OF RIB

BODY
DEMI-FACET FOR HEAD OF RIB
INFERIOR ARTICULAR PROCESS
-SPINOUS PROCESS
sides of the body, at the upper and lower angles, there are four demi-facets;
when two vertebræ are superimposed, the adjacent demi-facets form a complete
articular facet for the head of a rib.
The pedicles are two constricted short piers of bone projecting horizontally
backwards from the upper angles of the posterior surface. The lower border of
FIG. 6.-A THORACIC VERTEBRA.

FACET FOR TUBERCLE OF RIB-
DEMI-FACET FOR HEAD OF RIB-
Brodgronds Stonegua
BODY
each pedicle is deeply notched; hence, when two vertebræ are in position the
notches are converted into intervertebral foramina for the transmission of spinal
nerves and vessels.
The laminæ are broad plates of bone continuous with the pedicles; each
THE CERVICAL VERTEBRE
7

lamina meets its fellow dorsally to complete the neural arch, and conjointly form
the spinous process. The superior borders of the laminæ are rough for the
insertion of ligamenta subflava. The anterior surface, in its upper part, is smooth
where it bounds the neural canal. The lower part is rough for the origin of the
ligamenta subflava. This rough surface is continuous with the inferior border of
the spinous process.
The spinous process projects backwards and downwards from the confluent
laminæ. To its upper and lower borders the interspinous ligaments are attached;
its tip is rounded for the supraspinous ligament. It is mainly a muscular process.
The articular processes are four in number: two are superior and have the
articular facets directed backwards with a slight outward tendency; their ante-
rior surfaces complete the intervertebral foramina; posteriorly their margins give
attachment to capsular ligaments. The inferior articular processes are slightly
concave oval facets on the lower and outer angles of the anterior surface of the
laminæ. They are directed forwards and slightly inwards.
outwards from the
The tip presents an
When the rib is in situ its
The transverse processes are two in number, and jut
laminæ between the superior and inferior articular processes.
oval facet for articulation with the tubercle of the rib.
neck forms with the process a costo-transverse foramen. The transverse processes,
in addition to supporting the ribs, afford powerful leverage to muscles.
THE CERVICAL VERTEBRE
A typical cervical vertebra (from the third to sixth inclusive) presents the
following characters. The centrum is smaller than in other regions of the column,
and is of oval shape, the major axis being transverse. The upper surface has its
lateral margins raised into prominent lips, whilst the lower surface is somewhat
concave, its anterior margin being lipped so as to slightly overlap the anterior

FIG. 7.-A CERVICAL VERTEBRA.
COSTAL PROCESS
COSTO-TRANSVERSE FORAMEN-
TRANSVERSE PROCESS
SUPERIOR ARTICULAR PROCESS-
INFERIOR ARTICULAR PROCESS.
LAMINA-
SPINOUS PROCESS.
BODY
surface of the vertebra below. The inferior lateral margins are rounded, and
come into relation with the raised edges of the centrum next below.
The pedicles are directed obliquely outwards, and the intervertebral notch is
narrower above than below. The lamina are long and narrow. The spinous pro-
cess is short, and bifid at the extremity.
The superior articular processes look backwards and upwards; the inferior are
directed forwards and downwards.
The transverse process presents near its base the costo-transverse foramen for
the transmission of the vertebral artery, vein, and a plexus of sympathetic nerves.

8
THE SKELETON
The process behind the foramen has a shallow groove for the corresponding spinal
nerve. The extremity of the transverse process is bifid; each arm is terminated by
a tubercle referred to as anterior and posterior. The costo-transverse foramen is
very characteristic of a cervical vertebra. It is bounded posteriorly by the pedicle,
externally by the rudimentary transverse process, and anteriorly by a narrow bar
of bone springing from the centrum posterior to the neuro-central suture. This
thin bar is a vestigial rib, and will be referred to as the costal process.
The spinal foramen of all the cervical vertebræ is large, and somewhat
triangular in form.
Peculiar cervical vertebræ. The various cervical vertebræ possess distinguish-
ing features. The first, second, and seventh have characters so different from
their fellows as to render them peculiar.
THE ATLAS
This vertebra has neither body nor spinous process: it is an irregular ring of
bone with two thicker portions, the lateral masses, united anteriorly by a bridge,
the anterior arch, which constitutes one-fifth of the entire circumference. This
arch presents a tubercle on its anterior face for the anterior vertebral ligament and
the longus colli muscle; its posterior surface has a circular facet for the odontoid
process of the axis. The upper and lower borders are for ligaments.
The lateral masses are united posteriorly by a larger arch of bone, forming
two-fifths of the circumference. Posteriorly this arch has a tubercle, representing
a rudimentary spinous process. The upper and under surfaces of the arch afford
FIG. 8.-THE FIRST CERVICAL VERTEBRA OR ATLAS.

ANTERIOR TUBERCLE-
SUPERIOR ARTICULAR PROCESS
COSTAL PROCESS-
COSTO-TRANSVERSE FORAMENT
TRANSVERSE PROCESS
GROOVE FOR VERTEBRAL ARTERY
POSTERIOR TUBERCLE
TUBERCLES
FOR TRANSVERSE
LIGAMENT
attachment to ligaments. At the junction of the arch with the lateral masses
there is, on the upper surface, a deep groove which lodges the vertebral artery
and the suboccipital (first spinal) nerve. A bridge of bone sometimes con-
verts this into a foramen. A similar, but much shallower, notch is present on
the under surface; this, with the axis, forms an intervertebral foramen for the
second nerve. The atlas and axis are peculiar in that the first and second
spinal nerves issue behind the articular processes, whereas the remaining spinal
nerves emerge in front of the articular facets of the vertebræ. Each lateral mass
has, on its upper surface, an elongated, deeply concave articular fossa or cup.
These articular cups converge anteriorly. Occasionally each presents two oval
facets united by an isthmus. These cups receive the occipital condyles and permit
nodding movements of the head. The inferior articular processes are circular and
almost flat; they are directed downwards, with an inclination inwards, and rest
upon the axis, and permit rotatory movements of the head. Between the upper

EXCEPTIONAL CERVICAL VERTEBRE
9

and lower articular surfaces on the inside of the ring two tubercles exist for the
transverse ligament. This ligament divides the space within the ring into an
anterior smaller segment for the odontoid process of the axis, and a larger portion
-the spinal foramen of other vertebræ-for the spinal cord and its membranes.
The transverse processes are large, to serve for the attachment of muscles
which help to rotate the head. The costo-transverse foramina are large, but the
costal processes are slender.
THE AXIS
The Axis is easily recognised by the large rounded odontoid process which
surmounts its upper surface. The centrum has a more prominent lip than the
other cervical vertebræ, and the anterior surface has a median ridge separating
two lateral depressions.
The odontoid process is an irregularly rounded peg of bone. The anterior
surface has an oval facet for the anterior arch of the atlas. Posteriorly it presents
a deeply cut smooth groove for the transverse ligament. To the apex a thin narrow
FIG. 9.-THE AXIS.
ODONTOID PROCESS
GROOVE FOR TRANSVERSE LIGAMENT-
SPINE
LAMINA
FACET FOR ATLAS
SUPERIOR ARTICULAR PROCESS
COSTO-TRANSVERSE FORAMEN
BODY-
COSTAL PROCESS
INFERIOR ARTICULAR PROCESS
fibrous band (the suspensory ligament) is attached. On each side of the apex there.
is an oblique facet for the check ligaments which connect it with the occipital bone.
The pedicles are stout and broad; they support the oval, upwardly directed,
articular surfaces for the atlas. The inferior articular surfaces do not differ from
the cervical type. The transverse are smaller than the costal processes.
The spinous process is stout and strong, deeply concave on its under aspect,
and affords firm attachment for muscles, especially those which help to rotate
the head.
THE SEVENTH CERVICAL VERTEBRA
This vertebra has a longer spinous process than any other cervical vertebra,
hence it is sometimes called vertebra prominens. The extremity of this process
is not bifid, but has two small lateral tubercles which give attachment to the liga-
mentum nuchæ. The transverse processes are of large size; the costal processes
are very small; and the costo-transverse foramina are the smallest of the series.
Very frequently the costal process is segmented off, and constitutes a cervical rib,
sometimes of large size.
Occasionally a demi-facet exists on each side of the lower border of the centrum
for the head of the first rib. When this demi-facet is present, there is usually a
well-developed cervical rib.
The cervical vertebræ also exhibit great variation in regard to the extremities

10
THE SKELETON
of their spinous processes. As a rule among Europeans, the second, third, fourth,
and fifth vertebræ possess bifid spines. The sixth and seventh exhibit a tendency to
bifurcate, their tips presenting two small lateral tubercles; sometimes the sixth has
a bifid spine, and more rarely the seventh presents the same condition. Occasionally
all the cervical spines, with the exception of the second, are non-bifid, and even in
the axis the bifurcation is not extensive. In the lower races of men the cervical spines
are relatively shorter and more stunted than in Europeans generally, and, as a
rule, are simple. The only cervical vertebra which presents a bifid spine in all
FIG. 10.-THE CERVICAL VERTEBRE. (Anterior view.)
ANTERIOR TUBERCLE OF ATLAS
TO WHICH THE longus colli IS INSERTED
THE UPPER OBLIQUE
PORTION
longus colli
ATLAS
AXIS
23
II
OF-
ΠΙ
IV
THE UPPER OBLIQUE
PORTION OF longus
colli AND INSER--
TION OF INFERIOR
OBLIQUE PORTION
T
VI
VII
ORIGIN OF VERTICAL PORTION OF THE longus colli.
IT IS INSERTED INTO THE SECOND, THIRD, AND FOURTH VERTEBRÆ
Rectus capitis
anticus minor
THIS AND THE THREE
SUCCEEDING PRO-
CESSES GIVE ORIGIN
TO THE rectus capi-
tis anticus major
AND INSERTION TO
THE scalenus anti-
cus
races is the axis; even this may be non-bifid in the Negro, and occasionally in the
European. (Owen, Turner, Cunningham.)
The laminæ of the lower cervical vertebræ frequently present over the inferior
articular processes distinct tubercles from which fasciculi of the multifidus spina
muscle arise. They are usually confined to the sixth and seventh vertebræ, but
are fairly frequent on the fifth, and are occasionally seen on the fourth.
A large number of muscles are attached to the cervical vertebræ.
To the atlas:-Rectus capitis anticus minor, rectus capitis posticus minor,
rectus capitis lateralis, superior oblique, inferior oblique, longus colli, splenius
colli, intertransversales, levator anguli scapulæ.

MUSCULAR ATTACHMENTS
11
To the axis:-Rectus capitis posticus major, inferior oblique, longus colli,
splenius colli, intertransversales, interspinales, levator anguli scapulæ, transversalis
cervicis, the scalenus medius, semispinalis colli, and multifidus spinæ.
FIG. 11. THE CERVICAL VERTEBRE. (Posterior view.)
Rectus capitis
lateralis
Superior oblique
Inferior oblique
Rectus capitis posticus
major (The pointer
crosses the origin of
the inferior oblique),
Semispinalis colli
Rectus capitis posticus minor
TRANSVERSE PROCESS
OF ATLAS
Levator anguli
scapulæ (origin)
Splenius colli
(insertion)
Levator anguli scapulæ
Splenius capitis
Scalenus medius
(origin)
Cervicalis transversus
Semispinalis colli
Cervicalis transversus
Cervicalis ascendens
Levator anguli scapulæ
Splenius colli
Scalenus medius
Complexus
Levator anguli scapulæ
Splenius colli
(sometimes)
Scalenus medius
Complexus and multi-
fidus spinæ
Semispinalis colli
Cervicalis transversus
Cervicalis ascendens
Cervicalis transversus
Cervicalis ascendens
Semispinalis colli
Levator costæ (origin)
Accessorius (insertion)
Interspinales
Scalenus medius
Scalenus posticus
Complexus and
tracnelo-mastoid
Multifidus spinæ
Scalenus medius
Scalenus posticus
Complexus and
trachelo-mastoid
Multifidus spinæ
Scalenus medius
Scalenus posticus
- Complexus and
Tracnelo-mastoid
Multifidus spinæ
(The large surface is for
the multifidus spinæ)
Trapezius
Interspinales.
Rhomboideus minor
Serratus posticus superior
Splenius
Complexus
Multifidus spinæ (and to each spinous
process as high as the second)
To the seventh:-Trapezius, complexus, serratus posticus superior, splenius,
rhomboideus minor, multifidus spinæ, semispinalis, eight intertransversales, inter-
spinales, levator costæ, scalenus posticus, accessorius, scalenus medius, trachelo-
mastoid, and the longus colli.
12
THE SKELETON
THE THORACIC OR DORSAL VERTEBRÆ
The general characters of the thoracic vertebræ have already been considered
in the description of the type vertebra. Their most distinguishing features are the
FIG. 12. PECULIAR THORACIC VERTEBRE. (Modified from Gray.)

AN ENTIRE FACET ABOVE; A DEMI--
FACET BELOW. IN SHAPE THE
BODY RESEMBLES THAT OF A
CERVICAL VERTEBRA
USUALLY A DEMI-FACET
ABOVE
(SOMETIMES IT HAS A DEMI-FACET
BELOW)
USUALLY AN ENTIRE FACET ABOVE.
OCCASIONALLY THIS FACET IS IN-
COMPLETE. THE FACET ON THE
TRANSVERSE PROCESS IS USUALLY
SMALL
I
IX
AN ENTIRE FACET ABOVE. NONE
ON TRANSVERSE PROCESS, WHICH
IS SMALL. SOMETIMES IT HAS A
WELL-MARKED MAMMILLARY TU-
BERCLE. THIS IS THE ANTI-CLINAL
VERTEBRA
xie!!
AN ENTIRE FACET ABOVE; NO FACET
ON TRANSVERSE PROCESS. CENTRUM
LARGE. INFERIOR ARTICULAR PRO-
CESSES TURN OUTWARDS AS IN A
LUMBAR VERTEBRA; IT HAS ALSO A
WELL-MARKED MAMMILLARY PRO-
CESS
XII
facets on the transverse processes and sides of the bodies for the tubercles and
heads of ribs.
Peculiar thoracic vertebræ.-Several vertebræ in this series differ from the
type form. The exceptional are-the first, ninth, tenth, eleventh, and twelfth.
LUMBAR VERTEBRE
13
The first has a body resembling a cervical vertebra, the upper surface being
concave and lipped laterally; it has two entire facets above for the first pair, and
two demi-facets below for the second pair of ribs. The spinous process is thick,
strong, almost horizontal, and more prominent than the vertebra prominens.
Occasionally the transverse process is perforated near its root.
The ninth has demi-facets above, and usually none below; when the inferior
demi-facets are present, this vertebra is not exceptional.
The tenth usually has an entire costal facet at its upper border, on each side,
but occasionally only demi-facets. It has no lower demi-facets, and the facets on
the transverse processes are usually small.
The eleventh has a large body resembling a lumbar vertebra. The rib facets
are on the pedicles; they are complete and of large size. The transverse processes
are short and have no facets for the tubercles of the eleventh pair of ribs.
In many mammals the spines of the anterior vertebræ are directed backwards,
and those of the posterior directed forwards; in the centre of the column there is
usually one spine vertical. This is called the anti-clinal vertebra. It is at this
point that the thoracic begin to assume the characters of lumbar vertebræ. In
man, the eleventh thoracic is the anti-clinal vertebra.
The twelfth resembles in general characters the eleventh, but may be distin-
guished from it in having the inferior articular processes convex and turned
outwards as in the lumbar vertebræ. It also resembles a lumbar vertebra by
possessing well-marked mammillary and accessory tubercles. These tubercles are
occasionally present on the tenth and eleventh vertebræ.
A peculiarity, more frequent in the thoracic and lumbar than in the cervical
and sacral regions of the column, is the existence of a half-vertebra. Such speci-
mens have a wedge-shaped half-centrum, to which are attached a lamina, a
transverse, superior and inferior articular, and half a spinous process. As a rule, a
half-vertebra is ankylosed to the vertebræ above and below.

LUMBAR VERTEBRE
The distinguishing features of lumbar vertebræ are their large size; the
margins of the centrum are prominent; the pedicles are stout and strong; the
FIG. 13.-A LUMBAR VERTEBRA. (Side view.)
BODY
INFERIOR ARTICULAR PROCESS-
SUPERIOR ARTICULAR PROCESS
MAMMILLARY PROCESS
-TRANSVERSE PROCESS
ACCESSORY PROCESS
SPINE
inferior intervertebral notches are deep, and the laminæ are thick and strong.
The superior articular processes have concave facets directed backwards and
14
THE SKELETON
inwards, and their posterior borders are surmounted by rounded mammillary
processes or tubercles. The inferior articular processes have facets which look
forwards and outwards. The transverse processes are long, slender, and each
presents near the base, on the posterior aspect, a small accessory tubercle. The
spinous processes are thick, broad, and project horizontally backward.
FIG. 14.-A LUMBAR VERTEBRA.
(Showing the compound nature of the transverse process. Upper view.)

ACCESSORY
MAMMILLARY PROCESS.
PROCESS
OR TIP OF THE TRUE
TRANSVERSE PROCESS
COSTAL ELEMENT-
[COSTO TRANSVERSE-
FORAMINA
BODY
FIG. 15.-VARIATION IN THE FIFTH LUMBAR VERTEBRA. (After Turner.)

PEDICLE
FISSURE
LAMINA

The transverse processes of the lumbar vertebræ are more complex than they at first
appear. Each is compounded of a transverse and a costal process. The accessory process
represents the tip of the partially suppressed transverse process, and the part in front
is an undifferentiated rib. Between the transverse and costal elements some large vascular
foramina are usually present, representing the costo-transverse foramina of other vertebra.
Occasionally the costal element differentiates and becomes a well-developed lumbar rib.
LUMBAR VERTEBRE
15
A glance at the spine will show that the accessory tubercles are in line with the thoracic
transverse processes, and the costal elements are in series with the ribs (see also fig. 29).
The fifth lumbar vertebra has several distinguishing features. The centrum
is much thicker in front than behind. The inferior articular processes are widely
separated to articulate with the first sacral vertebra. The transverse processes
are of large size, and the spinous process is small.
FIG. 16.-A VARIATION IN THE FIFTH LUMBAR VERTEBRA. (After Turner.)

CENTRUM
SP
FISSURE
LAMINA
The pedicles of this vertebra are liable to a remarkable deviation from the conditions
found in other parts of the spine. The peculiarity consists of a complete solution in
the continuity of the arch immediately behind the superior articular processes. In such
specimens the anterior part consists of the body carrying the pedicles, transverse and
superior articular processes; whilst the posterior segment is composed of the laminæ, spine,
and inferior articular processes. The posterior segment of the ring of this vertebra may even
consist of two pieces. There is reason to believe that this abnormality of the fifth lumbar
vertebra occurs in five per cent. of all subjects examined. Sir William Turner, in his report
on the human skeletons in the Challenger' Reports, found seven examples among thirty
skeletons examined. The skeletons in which this occurred were: a Malay, an Andamanese,
a Chinese, two Bushmen, an Esquimaux, and a Negro. Turner has also seen it in the
skeleton of a Sandwich Islander.
THE SACRAL AND COCCYGEAL VERTEBRÆ
In the adult skeleton, the five vertebræ succeeding the lumbar series are firmly
ankylosed to form a single bone, the sacrum: the components of the sacrum are
termed sacral vertebræ. Beyond the fifth sacral, four, and occasionally five, other
rudimentary vertebræ to which the adjective coccygeal is applied, are ankylosed
in adult life, to form a single piece, the coccyx. In advanced life the coccyx unites
with the sacrum.
THE SACRUM
is a large triangular-shaped bone, firmly wedged between the innominate bones.
It forms the posterior boundary of the true pelvic cavity. The sacrum is curved
upon itself with the concavity looking forwards. The upper end of the curve
forms, with the body of the fifth lumbar vertebra, an anterior projection known
as the promontory. The middle portion of the anterior face of the sacrum
exhibits four transverse ridges corresponding to the intervertebral spaces. The
intervening portions are the bodies of the vertebræ. The upper two sacral vertebræ
are almost equal in size to those of the lumbar series, but the three lower
rapidly diminish in size from above downwards. The ridges terminate laterally

16
THE SKELETON
in the anterior sacral foramina, four pairs in all, which are the intervertebral
foramina of the sacral vertebræ, and transmit the anterior divisions of the first
four sacral nerves. The upper two are also traversed by the lateral sacral arteries.
The bone immediately outside the foramina corresponds to the costal processes,
and the portion formed by the second, third, and fourth sacral vertebræ gives
origin to the pyriformis muscle. The lateral part of the fifth sacral vertebra
gives partial insertion to the coccygeus.
The posterior surface is strongly convex and rough. The middle line is
occupied by four tubercles representing the suppressed spinous processes. Of these
the first is the largest, the second and third may be confluent, and the fourth
is often absent. The bone on each side of the spines is formed by the ankylosed
FIG. 17. THE SACRUM AND Coccyx. (Anterior view.)
WING
Coccygeus
-Levator Ani
-Iliacus
Pyriformis
Coccygeus
laminæ. In the fourth sometimes, but always in the fifth, the lamina fail to
meet in the middle line, and this leaves a gap, the hiatus sacralis. The median
borders of this hiatus are prolonged downwards as rounded processes, the sacral
cornua, to which the posterior sacro-coccygeal ligaments are attached. External
to the laminæ is a second series of small prominences: these are the articular
processes. The first pair are large for the last lumbar vertebra, the second and
third are small, and the fourth and fifth are inconspicuous.
Immediately external to the articular processes are the posterior sacral
foramina, four on each side; they are smaller than the anterior, and give exit to
the posterior divisions of the first four sacral nerves. External to the foramina
there are five eminences on each side, representing the transverse processes. The
first pair are large and conspicuous; the second form part of the articular surface

THE SACRUM
17
for the ilium; the third, fourth and fifth give attachment to ligaments and muscles.
The furrow formed by the laminæ, and bounded on the median aspect by the
spinous, and externally by the articular processes, is known as the sacral groove,
and lodges the erector spine muscle.
FIG. 18.-THE SACRUM. (Posterior view.)
bas
ARTICULAR PROCESS-
AURICULAR SURFACE
SPINOUS PROCESS
Latissimus dorsi
ARTICULAR PROCESS
TRANSVERSE PROCESS
SACRAL FORAMEN
HIATUS SACRALIS
LEADING INTO THE,
SACRAL CANAL
SACRAL CORNU.
NOTCH FOR FIFTH SACRAL NERVE
APEX
Multifidus
spinæ
Erector
spinæ
-Gluteus maximus
The upper surface, or base, of the sacrum resembles the corresponding aspect
of a lumbar vertebra, and its articular processes have well-marked mammillary
ARTICULAR PROCESS.
FIG. 19.-BASE OF SACRUM. a
LAMINA
SACRAL CANAL
TRANSVERSE
PROCESS
COSTAL
PROCESS
SPINE
BODY
bred lensiel adT
odi to bi
от Благо
tubercles. The conjoint transverse and costal processes form on each side a broad
surface, the wing or ala. From its margin the iliacus has a small point of origin.
The apex is directed downwards and forwards, and is formed by the inferior
aspect of the body of the fifth sacral vertebra; it articulates by means of an inter-
C

18
THE SKELETON
vertebral disc with the coccyx. In advanced life the coccyx and sacrum ankylose
at this spot.
The lateral surface presents in the upper two-thirds a broad irregular tract
called the auricular process, which is rough and, in the recent state, covered
with fibro-cartilage for union with the ilium. The margins are rough for ligaments.
Below the auricular surface the lateral borders are sharp and give attachment to
the greater and lesser sacro-sciatic ligaments. Near the extremity it presents a
notch which is converted into a foramen by articulation with the coccyx. Through
the space thus enclosed the anterior branch of the fifth sacral nerve issues. Some-
times the foramen is represented by a notch even when the sacrum and coccyx are
articulated. The middle of the sacrum is occupied by a continuation of the spinal
canal. It is triangular in form at the base, and flattened towards the apex. It
lodges the terminal branches of the cauda equina, the filum terminale, and the
lower extremity of the dura mater.
The sacrum exhibits sexual differences. In the female it is usually wider,
much less curved, and is directed more obliquely backwards, than in the male.
Muscles. The following muscles are attached to the sacrum :-Pyriformis,
coccygeus, iliacus, latissimus dorsi, multifidus spinæ, erector spinæ, gluteus
maximus; and the occasional muscles, namely, curvator coccygis, extensor coccygis,
and the agitator caudæ.
Ligaments.-Anterior and posterior common ligaments of the spine; anterior
and posterior sacro-coccygeal; greater and lesser sacro-sciatic, anterior and posterior
sacro-iliac, two capsular, ligamenta subflava, and the supraspinous.
THE COCCYX
The coccyx in the adult is made up of four and occasionally five vestigial
vertebræ ankylosed to one another. Rarely the number of segments is reduced to
three. The first two segments contain, in addition to the body of a vertebra, traces
of articular and transverse processes: the rest are mere nodules of bone, represent-
ing centra. The anterior surface gives attachment to the anterior sacro-coccygeal
ligament; and near its tip to the levator ani; it is in relation with the lower end
of the rectum.
The posterior surface is convex, and along its margin affords attachment to the
gluteus maximus muscle.
The lateral borders are thin: they receive parts of the greater sacro-sciatic
ligaments and of the coccygeus muscle. The base has an oval facet for the fifth
sacral vertebra, and presents the two long coccygeal cornua for the posterior sacro-
coccygeal ligament. The junction of the coccyx and sacrum completes the foramen
of exit for the fifth sacral nerve. In many skeletons the foramen is incomplete
externally. The apex is rounded and gives attachment to the sphincter ani, and
in front to the levator ani muscles.
ว
THE SPINAL COLUMN IN GENERAL
When the various vertebræ are in their relative positions, the whole is termed
the spinal column. It occupies the median line of the posterior aspect of the
trunk. Superiorly it supports the head; laterally it gives attachment to ribs; these
in their turn receive the weight of the upper limbs. Inferiorly, the sacrum affords
attachment to the innominate bones, by which the weight of the trunk is trans-
mitted to the lower limbs. The spinal column is the axis of the skeleton.
It varies in length in different persons, but on an average it measures, from the

Cervical
19
ATLAS-
THE SPINAL COLUMN
II
I
Lumbar
Caudal
Sacral
Thoracic
AXIS-
III
IV
V
VI
VII
VERTEBRA
PROMINENS
aute
I
Η
II
III
IV
VI
VII
VIII
IX
X
XI
THE ELEVENTH THORACIC S
THE ANTI-CLINAL VERTEBRA
V
FIG. 20.-THE SPINE.
(Lateral view.)
XII
Pistent
I
IV
II
H
III
Posterin
C 2
20
VY THE SKELETON
atlas to the tip of the coccyx, following the curve, 70 cm. (28"). Of this the
cervical spine measures 12.5 cm. (5"), the thoracic 27.5 cm. (11"), the lumbar
17.5 cm. (7"), and the sacro-coccygeal portion 12.5 cm. (5').
Viewed in profile, the column presents four curves: the first, or cervical, is
convex anteriorly; the thoracic is much larger and longer, with its concavity for-
ward; the lumbar curve has its convexity directed anteriorly, and ends somewhat
abruptly at the sacro-vertebral angle; and to this succeeds the pelvic curve, which
corresponds to the hollow of the sacrum. In addition to these, the whole column
has a slight lateral curve with the convexity to the right, probably due to muscular
action.
Viewed from the front, the superimposed bodies present three pyramids. The
first is formed by the cervical vertebræ from the second to the seventh. The
bodies of the lumbar and thoracic vertebræ form a much longer pyramid. The
third is inverted, and formed by the sacrum and coccyx.
Posteriorly, the column presents a median and two lateral rows of processes.
The median row is formed by the spinous processes. In the cervical spine, with
the exception of the first and the seventh, they are bifid. In the thoracic set they end
in rounded tubercles, are long, and for the most part directed obliquely downwards,
FIG. 21.-A DIVIDED THORACIC VERTEBRA. (After Turner.)

X
XI
IX
but in the lower part they become more horizontal until the eleventh is reached,
The spine of the eleventh thoracic vertebra is small and almost horizontal; this
is the anti-clinal vertebra. In the lumbar region the spinous processes are short,
stout plates of bone, with their borders set vertically; in the sacrum they are
vestigial, and in the coccyx completely suppressed.
The lateral rows are formed by the transverse processes, which are most marked
in the thoracic region, where they are rib-bearers. In the cervical spine they are
in the same plane as the ribs. The articular processes in the cervical region are
in series with the transverse processes of the thoracic vertebræ.
Between the ridges formed by the spinous and transverse processes we recognise
the vertebral grooves in which muscles are lodged. The floor of each groove is
formed by the lamina and articular processes, with their mammillary tubercles in
the lumbar and lower thoracic regions. Similar tubercles are present on the infe-
rior articular processes of the three lower cervical vertebræ. The intervertebral
foramina, oval in shape, are small in the cervical, but gradually increase in size
in the thoracic, and are largest in the lumbar region.
Ossification. The various ossific centres for the vertebræ are deposited in the
cartilage which, very early in embryonic life, surrounds the notochord and gradually
encloses the spinal cord.

THE VERTEBRE
21.
A typical vertebra arises from three primary and numerous secondary centres.
The primary centres appear during the sixth week of embryonic life. In the
thoracic region the nucleus for the body is first seen, but in the cervical region the
lateral centres make their appearance somewhat earlier. The nucleus for the body
is deposited around the centre, and quickly becomes bilobed. This bilobed, or
dumb-bell, shape is often so pronounced as to give rise to the appearance of
two distinct nuclei. Sometimes the nucleus is double, and remains separate
throughout life, the vertebra being divided by a vertical fissure (fig. 21). The bifid
character of the nucleus of the vertebral body is further emphasised by the occasional
FIG. 22.-A VERTEBRA AT BIRTH.

-LATERAL MASS
NEURO-CENTRAL SUTURE
CENTRUM OR BODY
occurrence of half-vertebræ. The lateral centres are deposited near the bases of
the superior articular processes, and give rise to the pedicles, laminæ, articular
processes, and a large part of the transverse and spinous processes.
At birth a vertebra consists of three parts-a body and two lateral masses
connected by hyaline cartilage. The line of union of the lateral masses with the
bodies is known as the neuro-central suture (fig. 22), and this is not obliterated for
several years after birth. An examination of a thoracic vertebra at the fifth year
will show that a portion of the body of each vertebra is derived from the lateral
masses, and that the demi-facets for the rib-heads are situated behind the neuro-
central suture, and therefore belong to the pedicles.
During the early years growth progresses rapidly, and at puberty the secondary
FIG. 23.-LUMBAR VERTEBRA AT THE EIGHTEENTH YEAR WITH SECONDARY CENTRES.
EPIPHYSIAL PLATE OR DISC
EPIPHYSIAL PLATE OR DISC
MAMMILLARY TUBERCLE
-TRANSVERSE PROCESS
SPINOUS PROCESS
centres make their appearance in the cartilaginous tips of the transverse and
spinous processes. During the seventeenth year a meniscus of bone forms around
the margins of the superior and inferior surfaces of the centra. These are the
epiphysial discs; they are thickest at the periphery, and gradually become thin
towards the central perforation. By the twenty-fifth year the various secondary
nuclei have coalesced with the main bone, and the vertebra is then complete.
In several vertebræ the mode of ossification deviates from the account given
above, and requires separate consideration.
The atlas.-This bone has three primary centres-one for each lateral mass

22
THE SKELETON
(neural arch) appearing in the sixth week of embryonic life. The third appears
a few months after birth for the anterior arch. The lateral portions coalesce
posteriorly about the third year; the union with the anterior nucleus is delayed
until the sixth year. An additional centre occasionally appears for the posterior
segment.
FIG. 24. IMMATURE ATLAS. (Third year.)
The axis. This is the most exceptional of all the vertebræ. It has the usual
three primary nuclei-one for the body, and one on each side for the neural arch.
The centre for the body appears in the embryo about the fifth month, and a few
weeks later two laterally disposed nuclei are seen for the base of the odontoid
FIG. 25.-DEVELOPMENT OF THE ATLAS.
Suspensory ligament
NUCLEUS FOR TIP OF ODONTOID PROCESS
LATERAL CENTRES FOR ODONTOID PROCESS-
EPIPHYSIAL PLATE OR DISC-
PEDICLE-
CENTRUM OR BODY-
EPIPHYSIAL PLATE-
process; these fuse together in the middle line, and by the third year ankylose
peripherally to the centrum of the axis. The line of union between the body of
the axis and the odontoid process is indicated even in advanced life by a persistent
FIG. 26. THE AXIS (FROM AN ADULT) IN SECTION.
ODONTOID PROCESS
CARTILAGE REPRESENTING
THE INTERVERTEBRAL DISC
BETWEEN THE ODONTOID
PROCESS AND THE BODY
OF THE AXIS
BODY OF AXIS
lenticular-shaped cartilage. During the second year a nucleus appears at the tip
of the odontoid process. An epiphysial meniscus for the inferior and superior
surfaces of the centrum of the axis appears about the seventeenth year. As a rule,
the superior meniscus is represented by a few earthy granules.

THE VERTEBRE
23
The sixth and seventh vertebræ.-In the cervical vertebræ the pedicles, or
anterior extremities of the neural arches, take a much larger share in forming the
centrum than is the case with the remaining vertebræ. The sixth, seventh, and
possibly other cervical vertebræ present an additional centre on each side of the
neural arch for the costal process; it appears before birth. The costal processes
of the seventh cervical not infrequently fail to ankylose with the vertebra; when
this is the case, the processes become cervical ribs. Sometimes these ribs are of
large size.
The lumbar vertebræ.-In the lumbar vertebræ two additional centres make
their appearance, about puberty, namely, for the mammillary tubercles on the
posterior aspect of each superior articular process.
FIG. 27.-AN IMMATURE CERVICAL VERTEBRA.
NEURO-CENTRAL SUTURE
The fifth lumbar occasionally differs in the mode of ossification of its arch;
in
many
skeletons this arch is derived from four nuclei. There is a nucleus on each
side for the pedicle, the transverse process, and the superior articular process; and
one on each side for the lamina, inferior articular process, and the lateral half of
the spinous process (fig. 28). The pedicles may fail to join the lamina; more rarely
the laminæ fail to fuse (fig. 16).
FIG. 28.-OSSIFICATION OF THE FIFTH LUMBAR VERTEBRA.
LAMINA
SUTURE
PEDICLE
NEURO-CENTRAL SUTURE.
CENTRUM
The sacral vertebra. In addition to the three primary vertebral centres,
the three upper sacral vertebræ have each an extra pair corresponding to the
costal processes of the seventh cervical vertebra. These processes are very large in
the first sacral, smaller in the second, and very small in the third. Although the
various primary centres of the sacral vertebræ appear much later than in other
regions of the column, yet they are all. visible at birth. The centrum of each
sacral vertebra develops a superior and inferior epiphysial meniscus, and eventually
the five vertebræ fuse to form a single bone, the sacrum. Even in advanced life the
intervertebral discs between the sacral vertebræ persist in the centre of the bone.
The ear-shaped lateral articular facet on the side of the sacrum arises from two
additional centres on each side, about the eighteenth year. The total number of
ossific centres for the sacrum is thirty-five.
24
THE SKELETON
The coccygeal vertebræ.-These are cartilaginous at birth. A few months
later the first segment ossifies. The remaining three ossify from above downwards
FIG. 29.-MORPHOLOGY OF THE TRANSVERSE AND ARTICULAR PROCESSES.

COSTAL PROCESS
CERVICAL
VERTEBRA
THORACIC
VERTEBRA
LUMBAR
VERTEBRA
SACRAL
VERTEBRA
༼/7
TRANSVERSE PROCESS
COSTO-TRANSVERSE FORAMEN
NEURO-CENTRAL SUTURE
CERVICAL RIB

-TRANSVERSE PROCESS
COSTO-TRANSVERSE FORAMEN
NEURO-CENTRAL SUTURE
RIB
TRANSVERSE PROCESS
LUMBAR RIB
NEURO-CENTRAL SUTURE
COSTAL PROCESS
imal ads
before the fifteenth year. By the twentieth year the first three have usually
coalesced. The fourth fuses with them later, and the coccyx ankyloses with the
sacrum, as a rule, late in life.

THE VERTEBRE
25
The Serial Morphology of the Vertebra
Although at first sight many of the vertebræ exhibit peculiarities, nevertheless a study
of the mode by which they develop, and their variations, indicates the serial homology of
the constituent parts of the vertebræ in each region of the column.
The centrum, or body of the vertebra, is that part which immediately surrounds the
notochord. This part is present in all the vertebræ of man, but the centrum of the atlas
is dissociated from its neural arch, and ankylosed to the body of the axis. The reasons
for regarding the odontoid process as the body of the atlas are these: In the embryo the
notochord passes through it on its way to the base of the cranium. Between the odontoid
process and the body of the axis there is a swelling of the notochord in the early embryo
as in other intervertebral regions. This swelling is later indicated by a small inter-
vertebral disc hidden in the bone, but persistent even in old age. The odontoid process
arises from primary centres, and in chelonians it remains as a separate ossicle throughout
life; in Ornithorhynchus it remains distinct for a long time, and it has been found separate
even in an adult man. Lastly, in man and many mammals, an epiphysial plate develops
between it and the true body of the axis.
The anterior segment of the atlas is in no sense homologous with a centrum, and is
most probably an enlarged hypapophysis or subvertebral wedge-bone, which, in lizards,
exists on the ventral aspect of the column between individual centra. Similar ossicles
occur in the lumbar region of the mole.not
The neural arches and spinous processes are easily recognised throughout the various
parts of the column in which complete vertebræ are present.
The articular processes are of no morphological value, and do not require consideration
here.
The transverse processes offer more difficulty. They present themselves in the
simplest form in the thoracic series. Here they articulate with the tubercles of the ribs.
The transverse process and the neck of the rib enclose an arterial foramen, the costo-
transverse. In the cervical region this rib, or costal element, and the transverse process
are fused together, but the conjoint process thus formed is pierced by the costo-transverse
foramen. The compound nature of the process is indicated by the fact that the anterior
or costal processes in the lower cervical vertebræ arise from additional centres and
occasionally retain their independence as cervical ribs. These processes in Sauropsida
(birds and reptiles) are represented by free ribs. In the lumbar region the compound
nature of the transverse process is further marked. The true transverse process is greatly
suppressed, and its extremity is indicated by the accessory tubercle. Anterior to this in
the adult vertebra a group of holes represent the costo-transverse foramen, and the portion
in front of this is the costal element. Occasionally it will persist as an independent
ossicle, the lumbar rib.
In the sacral series the costal elements are peculiarly modified in the first three vertebræ
to form piers of bone for articulation with the ilium. The costo-transverse foramina are
completely obscured. In rare instances the first sacral vertebra will articulate with the
ilium on one side, but remain free on the other. Under such conditions the free process
exactly resembles the elongated transverse process of a lumbar vertebra. The first three
sacral vertebræ which develop a costal process (rib) for articulation with the ilium are
true sacral vertebræ. Those ankylosed below these are pseudo-sacral. A glance at
fig. 29 will show the homology of the various parts of a vertebra from the cervical,
thoracic, lumbar and sacral regions.
The mammillary processes are vestiges of the greatly elongated articular processes of
such mammals as the dog, armadillo, &c.
20

26
THE SKELETON
THE BONES OF THE SKULL
The skeleton of the head is called the skull: it contains, in the adult, twenty-
nine separate bones. For descriptive purposes they are divided in two groups:
those of the skull proper, and the appendicular elements.
I. THE SKULL
Occipital.
(a) Basilar Bones Sphenoid.
Temporals.
Parietals.
(b) Roof Bones
Frontal.
Epipterics.
Ethmoid.
Sphenoidal tur-
binals.
(c) Nasal Region Turbinals.
Maxillæ.
(d) Facial Bones Palatines.
Malars.
Lachrymals.
Vomer.
Nasals.
II. APPENDICULAR ELEMENTS
Mandible.
Malleus.
Incus.
Stapes.
Hyoid.
Styloid.
Internal pterygoid.
The epipterics are not always separate in the adult skull: the styloid ankyloses
with the temporal, and the internal pterygoid with the sphenoid.
THE OCCIPITAL
This bone forms the back and a portion of the base of the skull. At birth
it consists of four distinct parts disposed around the foramen magnum (fig. 34).
These, in the adult, fuse together and form a single bone, which ankyloses with
the sphenoid. The four parts of the occipital are the squamo-occipital, two
ex-occipitals, and a basi-occipital. The lines of union of these parts are easily
distinguished even in the oldest skull.
The squamo-occipital is saucer-shaped, deeply concave on its cerebral, but
convex on its external aspect. It consists of two parts which have different modes
of origin. The posterior surface is divided by a ridge, the superior nuchal line,
into a lozenge-shaped superior portion with a smooth surface and an inferior rough
portion. The upper is the interparietal, and the lower the supra-occipital segment.
The interparietal portion not infrequently persists as an independent ossicle (fig. 35).
The supra-occipital is divided into two lateral halves by a median vertical
ridge the external occipital crest-which ascends from the middle of the posterior
margin of the foramen magnum, to terminate at the external occipital protuber-
ance, or inion, near the middle of the squamo-occipital. The protuberance and
crest give attachment to the ligamentum nuchæ.
Each lateral half of the supra-occipital presents three pairs of transverse ridges,
the nuchal lines. Of these the superior is usually the least conspicuous, but
most curved; frequently it is absent; beginning at the external occipital pro-
tuberance, it curves outwards to the lateral angle. It affords attachment to the
epicranial aponeurosis and to few fibres of the occipito-frontalis muscle.
The middle nuchal line (sometimes called the superior curved line) commences
a little distance below the protuberance, and curves outwards to end below the

THE OCCIPITAL
27
lateral angle. In some cases the superior and middle nuchal lines are confluent in
their outer thirds, and form a prominent ridge for the insertion of the sterno-
mastoid and splenius capitis muscles. When these muscles are well developed,
there is a fairly wide interval between the lines.
The inferior nuchal line begins near the middle of the crest and curves
downwards to the jugular process.
Of the spaces deliminated by these lines, that between the superior and middle
is occupied by the trapezius, and frequently by the sterno-mastoid and splenius
capitis muscles. The space between the middle and inferior receives the complexus,
and the space between the inferior line and the foramen magnum is occupied by
the rectus capitis posticus minor, rectus capitis posticus major, and the superior
oblique muscles.
The cerebral surface is deeply concave, and divided by crucial ridges into four
fossæ, of which the upper two accommodate the occipital lobes of the cerebrum,
the lower pair the cerebellar hemispheres. The ridges intersect each other, and
SUPERIOR NUCHAL LINE
FIG. 30. THE OCCIPITAL. (External view.)
Trapezius
INION OR EXTERNAL-OCCIPITAL PROTUBERANCE
Occipito-frontalis-
Sterno-mastoid-
MIDDLE NUCHAL LINE
Splenius capitis.
Rectus cap. post. min.-
Rectus cap. post. maj.-
Superior oblique
Complexus
CREST
INFERIOR NUCHAL LINE
FORAMEN
MAGNUM
POSTERIOR
CONDYLOID
FORAMEN
CONDYLE
Rectus capitis lateralis-
JUGULAR
PROCESS
-BASI-OCCIPITAL
is seen.
at the point where they cross an eminence, the internal occipital protuberance,
The vertical ridge runs upwards to the superior angle of the bone
and furnishes attachment for the falx cerebri; the portion of the ridge below
the protuberance, the internal occipital crest, is for the falx cerebelli. As it nears
the foramen magnum this ridge divides, becoming lost upon its margins. The
angle of divergence is often occupied by a shallow fossa for the extremity of the
vermiform process of the cerebellum, and is called the vermiform fossa. The
horizontal ridge is deeply grooved; to the edges of the groove the tentorium cerebelli
is attached, the grooves lodge the greater part of the lateral sinuses.
side of the internal occipital protuberance, usually the right, the furrow for the
sinus is deeper and frequently forms a circular fossa which receives the torcular.
This fossa is sometimes exactly in the middle line.
The squamo-occipital has three angles and four borders.
fits into the space formed by the union of the two parietals.
To one
The superior angle
The lateral angles
mark the external limits of the middle nuchal lines, and occupy the angle formed

28
THE SKELETON
FOR SUPERIOR LONGI-
TUDINAL SINUS AND
FALX CEREBRI
CEREBRAL FOSSA-
GROOVE FOR LATERAL
SINUS
LATERAL ANGLE
CEREBELLAR FOSSA-
GROOVE FOR LATERAL
SINUS
JUGULAR PROCESS
FOR PETROSAL
FIG. 31.-OCCIPITAL BONE, CEREBRAL SURFACE.
SUPERIOR ANGLE
CUT SURFACE OF THE
BASI-OCCIPITAL
FIG. 32.-CEREBRAL SURFACE OF THE OCCIPITAL, SHOWING AN OCCASIONAL
DISPOSITION OF THE CHANNELS.
TORCULAR
VERMIFORM FOSSA
POSTERIOR CONDYLOID FORAMEN-
ANTERIOR CONDYLOID FORAMEN-

FORAMEN MAGNUM
29
The ridge
by the parietal and mastoid portion of the petrosal on each side.
between the superior and lateral angles is the superior border; it is serrated
deeply, and articulates with the posterior border of the parietal to form the
lambdoid suture. The inferior border extends from the lateral angle to the
jugular process; it articulates with the mastoid portion of the petrosal.
The ex-occipitals form the lateral boundaries of the foramen magnum, and
extend from the ridge immediately behind the groove for the termination of the
lateral sinus to the tubercle in front of the anterior condyloid foramen. The
lateral surface of each ex-occipital is extended outwards to form a quadrilateral
buttress of bone, the jugular process. This has an outer rough surface for articu-
lation with the jugular surface of the petrosal. Its anterior border is deeply
notched to form the posterior boundary of the jugular foramen, and is directly
continuous with a groove which lodges the termination of the lateral sinus. Its
under surface gives attachment to the rectus capitis lateralis and the oblique
occipito-atlantal ligament. The pneumatic mastoid cells occasionally extend
into this process. Rarely a process of bone extends from its under surface and
FIG. 33. THE FORAMEN MAGNUM AT THE SIXTH YEAR.
POSTERIOR CONDYLOID FORAMEN-
EX-OCCIPITAL PORTION OF THE CONDYLE-
JUGULAR PROCESS.
ANTERIOR CONDYLOID FORAMEN.
BASI-OCCIPITAL PORTION OF THE CONDYLE
BASI-OCCIPITAL
bool
represents the par-occipital process present in many mammals. The rest of the
ex-occipitals enter into the formation of the condyles, and will be separately
described.
The basi-occipital is a quadrilateral plate of bone. Its superior surface is
concave for the medulla oblongata. Inferiorly it is rough, and presents the
pharyngeal tubercle, to which the median portion of the fibrous bag of the pharynx
is attached. The rectus capitis anticus major and minor muscles are inserted into
this surface. Anteriorly the basi-occipital is, in the adult, ankylosed to the basi-
sphenoid. Posteriorly it has a smooth, rounded, narrow, concave border forming
the anterior boundary of the foramen magnum.
The extremities of this border enlarge to join the ex-occipitals, and form the
anterior extremities of the condyles. The lateral borders are rough, and articulate
with the inferior border of the petrosals.
The foramen magnum is oval in shape, with its major axis in the long axis of
the skull. Near the middle it is encroached upon by the condyles. It is bounded
posteriorly by the supra-occipital, anteriorly by the basi-occipital, and laterally by
the ex-occipitals. Sometimes a facet exists at the anterior margin for articulation
with the odontoid process.
This is the tertiary occipital condyle. The margin

30
THE SKELETON
of the foramen gives attachment behind the condyles to the posterior occipito-
atlantal ligament.
The condyles are two oval processes of bone, with smooth articular surfaces,
covered in the recent state with cartilage. They are received into the superior
articular cups of the atlas. The condyles converge anteriorly but diverge posteriorly.
Their margins give attachment to capsular ligaments, and a prominent tubercle in
the middle of the median border of each condyle is for the check ligament. A
foramen, the anterior condyloid, traverses the upper part of each condyle; it
transmits the hypoglossal nerve, and a twig of the ascending pharyngeal artery with
its venæ comites. Frequently the foramen is divided by a delicate spicule of bone.
Posterior to each condyle is a depression, the posterior condyloid fossa, which receives
the hinder edge of the articular cavity of the atlas when the head is extended; the
floor of this depression is occasionally perforated by the posterior condyloid foramen,
which transmits a vein from the lateral sinus.
Articulations.-The occipital bone is connected by suture with the two parietals,
the two temporals, and the sphenoid; by means of the condyles it articulates with
the atlas; and under the exceptional condition of a tertiary occipital condyle, with
the odontoid process of the axis.
Muscles. Attached to the occipital bone :-

Occipito-frontalis.
Trapezius.
Sterno-cleido-mastoid.
Rectus capitis anticus major.
Rectus capitis anticus minor.
Rectus capitis posticus major.
Complexus and biventer cervicis.
Splenius capitis.
Rectus capitis posticus minor.
Rectus capitis lateralis.
Superior oblique.
Ligaments:-
Ligamentum nucha.
Capsular.
Posterior occipito-atlantal.
Anterior occipito-atlantal.
Oblique occipito-atlantal.
Azygos pharyngei (when present).
Suspensory ligament.
Check ligaments.
Vertical slip of the crucial.
Posterior common ligament of spine.
Anterior common ligament of spine.
The fibrous bag of the pharynx.
Blood-supply. The occipital bone receives branches from the occipital,
posterior auricular, middle meningeal, vertebral and ascending pharyngeal
arteries.
Development. The interparietal portion of the occipital is a membrane bone, and
arises by two or more centres about the twelfth week; these nuclei rapidly become
confluent and fuse with the supra-occipital portion about the fifteenth week.
Occasionally this fusion fails. The centres for the rest of the bone are deposited
in cartilage. The nucleus for the basi-occipital appears in the tenth week, and is
quickly followed by a nucleus for each ex-occipital; the supra-occipital ossifies
from two laterally disposed nuclei, which quickly coalesce and fuse with the inter-
parietal portion near the situation of the future occipital protuberance. For many
weeks two deep lateral fissures separate the interparietal and supra-occipital por-
tions, and a membranous space, extending from the centre of the squamo-occipital
to the foramen magnum, partially separates the lateral portions of the supra-
occipital. This space becomes occupied by a spicule of bone, and is of interest,
because through it hernia of the brain and its membranes, known as meningo-
cele or encephalocele, occurs.
At birth the occipital consists of four parts: the squamo-occipital, two
ex-occipitals, and the basi-occipital, united by strips of cartilage. The ex-occipitals

THE OCCIPITAL
31
and squamo-occipital fuse together about the fifth year, and unite with the basi-
occipital before the seventh year. The posterior two-thirds of each occipital condyle
belongs to the ex-occipitals, and the anterior third to the basi-occipital (fig. 33).
FIG. 34. THE OCCIPITAL AT BIRTH. (Anterior view.)
INTERPARIETAL PORTION
(DEVELOPS IN MEMBRANE)-
THE
INTERPARIETAL AND
SUPRA-OCCIPITAL POR-
TIONS FORM THE SQUAMO-
OCCIPITAL OF THE ADULT
SUPRA-OCCIPITAL PORTION
(DEVELOPS IN CARTILAGE)
EX-OCCIPITAL
FORAMEN
MAGNUM
BASI-OCCIPITAL
FIG. 35. THE OCCIPITAL WITH A SEPARATE INTERPARIETAL.
INTERPARIETAL.
Not infrequently the interparietal portion remains separate throughout life, and
may even be represented by numerous detached ossicles or Wormian bones. By
the twenty-fifth year the basi-occipital is firmly ankylosed to the sphenoid.

32
THE SKELETON
THE SPHENOID
The sphenoid forms a large part of the base of the skull in the region of the
anterior and middle fossæ. It is very irregular in shape, and is best described as
consisting of a body, two pairs of wings, and two pairs of
processes.
The body is irregularly cuboidal in shape. The superior surface presents the fol-
lowing points for examination. In front, there is a prominent spine, which is received
between the diverging alæ of the crista galli, and known as the ethmoidal spine.
The surface behind this is smooth, and is formed by the lesser or orbital wings; it
frequently presents two parallel longitudinal grooves for the olfactory nerves.
This smooth surface is terminated by the optic groove, which lodges the optic
chiasma, and leads on each side into the optic foramen. The groove is bounded
posteriorly by the olivary eminence, a ridge of bone indicating the line of union
of the pre- and post-sphenoid. Behind this ridge the bone presents a deep
hollow, the pituitary fossa, in which the pituitary body is lodged. The floor of
this fossa presents numerous foramina for blood-vessels, and at birth the superior
orifice of a narrow passage termed the cranio-pharyngeal canal. The pituitary
fossa presents on each side, slightly posterior to the olivary eminence, a tubercle
FIG. 36. THE SPHENOID. (Viewed from above.)
OPTIC FORAMEN
SPHENOIDAL FISSURE.
FORAMEN ROTUNDUM
FORAMEN OVALE
FORAMEN SPINOSUM
LESSER WING
GREATER
WING
SPINE OF THE SPHENOID
EXTERNAL PTERYGOID PLATE
INTERNAL PTERYGOID PLATE
PTERYGOID NOTCH
HAMULAR PROCESS
of variable size, the middle clinoid process. This is occasionally prolonged to
meet the anterior clinoid process on the orbital wing. The posterior boundary is.
formed by a quadrilateral plate of bone, the dorsum ephippii. The superior
angles of this plate are surmounted by the posterior clinoid processes, which give
attachment to the tentorium cerebelli. A little below the clinoid process, on
each side of the dorsum ephippii, there is a deep notch, converted into a fora-
men by the dura mater, for the passage of the sixth cranial nerve. The dorsum
is slightly concave posteriorly, and supports the basilar artery and the pons.
Varolii.
The inferior surface of the body has a prominent median ridge, the rostrum, which
is received between the alæ of the vomer. The rest of the surface is rough, and
covered by the mucous membrane belonging to the roof of the pharynx.
The anterior surface presents in the middle line a vertical ridge of bone, the
sphenoidal crest, which articulates with the perpendicular plate of the ethmoid.
On each side of the crest, a more or less circular orifice leads into the sphenoidal
sinuses. These sinuses are irregularly shaped, unsymmetrical cavities, separated
from each other by a thin vertical septum; in adult bones they may extend
into the roots of the pterygoid processes, and even into the base of the occipital

THE SPHENOID
33
bone. The sinuses communicate with the nasal fossa of their respective sides.
The lateral margins of the anterior surface are serrated for articulation with the
posterior border of the os planum on each side of the ethmoid. The superior
margin articulates with the cribriform plate of the ethmoid.
The posterior surface is, in the adult, ankylosed to the basi-occipital. The two
bones are separated by a disc of hyaline cartilage until the eighteenth year; by the
twenty-fifth year ankylosis is complete.
On each side of the body there is the broad sinuous cavernous groove, which
lodges the internal carotid artery and the cavernous sinus. The process of bone
over which this artery turns is the lingula; it constitutes a flying buttress for the
support of the greater wings.
The lesser or orbital wings (orbito-sphenoids) are thin, triangular, horizontal
plates of bone resting upon that portion of the sphenoid anterior to the olivary
ridge (pre-sphenoid). The superior surface of each wing is smooth and slightly
concave, and forms the posterior part of the anterior fossa of the skull; the under
surfaces constitute a portion of the roof of each orbit, and bound superiorly the
sphenoidal fissures. The anterior border is serrated for articulation with the
horizontal plate of the frontal bone. (The orbital wings meet over the pre-sphenoid
FIG. 37. THE LEFT HALF OF THE SPHENOID.
ANTERIOR CLINOID PROCESS.
MIDDLE CLINOID PROCESS.
POSTERIOR CLINOID PROCESS-
ETHMOIDAL SPINE
OPTIC GROOVE
OLIVARY EMINENCE
-DORSUM EPHIPPI
-FOR OCCIPITAL
and almost exclude it from the cranial cavity.) The posterior border, smooth and
rounded, is received into the Sylvian fissure of the cerebrum. The inner extremity
is prolonged to form the anterior clinoid process to which the tentorium cerebelli is
attached. Each lesser wing is connected to the body of the bone by two processes
or roots; of these, the upper is thin and flat, the lower one is thicker, and presents
near its junction with the body a small tubercle for the attachment of the common
tendon of three ocular muscles. The space between the roots is the optic foramen,
and transmits the optic nerve and ophthalmic artery.
The greater wings (ali-sphenoids) are two large plates of bone ankylosed to the
body by means of the lingulæ. Each wing has three surfaces. The superior or
cerebral surface is concave and smooth; it receives the temporo-sphenoidal lobe of
the cerebrum, and presents several foramina. At the anterior and internal part is
the foramen rotundum for the second division of the fifth nerve; behind and
external to this is the foramen ovale, for the motor root and the third division of
the fifth nerve, the small petrosal nerve, and the small meningeal artery. Behind
and external to the foramen ovale is the small circular foramen spinosum, for the
middle meningeal artery and its venæ comites. To the inner side of the foramen
ovale a small opening, the foramen Vesalii, is occasionally present; it transmits
a vein. A foramen may exist near the foramen ovale for the small superficial
D

34
THE SKELETON
petrosal nerve. The external surface is divided by the prominent malar crest
into an orbital and a temporo-zygomatic portion. The orbital surface forms the
chief part of the outer wall of the orbit; its internal segment forms part of the
spheno-maxillary fossa, and presents the anterior orifice of the foramen rotundum.
Near the middle of the upper border there is a small tubercle for the origin of the
outer head of the external rectus muscle; and at the highest part of this surface
FIG. 38. THE SPHENOID. (Anterior view.)
ORBITAL SURFACE.
(THE POINTER
CROSSES THE
MALAR CREST)
PTERYGO-
EXT. PTERYGOID PLATE
PALATINE
CANAL
PTERYGOID NOTCH
HAMULAR PROCESS
OPTIC FORAMEN
SPHENOIDAL
FISSURE
FORAMEN ROTUNDUM
VIDIAN CANAL
one or more foramina are often present, for the transmission of twigs from the
middle meningeal artery to the orbit and the lachrymal gland. The malar crest
is serrated for articulation with the malar bone; its lower angle, in many bones,
articulates with the maxilla. A foramen exists in the suture between the sphenoid
and malar, for the temporal twig of the orbital nerve. The surface of bone outside
this ridge is subdivided by a low crest, the pterygoid ridge. The surface above
the ridge forms part of the temporal fossa, and affords attachment to the temporal
FIG. 39.-RIGHT HALF OF SPHENOID. (Anterior view.)
TEMPORAL SURFACE
RIDGE WHICH FORMS THE
UPPER BOUNDARY OF
THE SPHENO-MAXIL-
LARY FISSURE
Ext. Pterygoid Muscle
THE ALAR SPINE
SPHENOIDAL CREST
SPHENOIDAL SINUS
muscle; the part behind the crest belongs to the zygomatic fossa, it furnishes
attachment to the external pterygoid muscle, and is continuous with the outer
surface of the external pterygoid plate; it contains the inferior orifices of the
foramina spinosum, ovale, and Vesalii.
The circumference of the great wing, commencing at its anterior attachment
to the body, is at first smooth, and forms the lower boundary of the sphenoidal

THE SPHENOID
35
fissure; this serves for the passage of the third, fourth, first division (ophthalmic)
of the fifth, and the sixth nerves, with the ophthalmic vein. External to this, the
margin is broad and serrated for the frontal bone; quite at the tip it is bevelled on
its inner aspect for the anterior inferior angle of the parietal; behind this, the
edge, at first thin and bevelled, becomes gradually broader, and deeply serrated
for the squamosal, and runs into the prominent alar spine of the sphenoid, to which
the spheno-mandibular ligament is attached. That portion of the circumference
extending from the spine to the body of the sphenoid articulates by the outer third
with the petrosal, but the inner two-thirds forms the anterior boundary of the
foramen lacerum medium, and contains the posterior orifice of the Vidian canal.
Projecting at right angles from the greater wing, near its junction with the
lingulæ, are the pterygoid processes. Of these, the external, broad and thin,
forms by its outer surface the inner wall of the zygomatic fossa, and affords
attachment to the external pterygoid muscle. From its inner surface the internal
pterygoid takes origin.
The internal pterygoid plate is narrower and longer than the external. Its
inner surface forms part of the outer boundary of the nasal fossa, and by a thin
ledge of bone, called the vaginal process, extends to the under surface of the basi-
sphenoid to articulate with the ala of the vomer, and anteriorly with the sphenoidal
process of the palate bone. Immediately above this ledge of bone is the pterygo-
palatine groove (converted into a canal by the sphenoidal process of the palate
bone), for an artery and nerve of the same name. At the point where the internal
pterygoid plate comes into relation with the great wing and the lingula, there is
the Vidian canal. This canal is 3 cm. long, and transmits the Vidian nerve and
artery. The outer surface of the internal pterygoid plate forms the inner boundary
of the pterygoid fossa; its posterior border is prolonged into a hamular process,
smooth on its under aspect, for the bursa between it and the tensor (circumflexus)
palati. From the lower third of the posterior border and the hamular process the
superior constrictor of the pharynx takes origin.
The anterior borders of these processes diverge below, and have rough edges
for articulation with the tuberosity of the palate bone; the gap between them is
the pterygoid notch. Above, the pterygoid processes form a triangular surface,
which constitutes the posterior boundary of the spheno-maxillary fossa, and presents
above the anterior orifice of the Vidian, and more internally the commencement
of the pterygo-palatine canals. The anterior border of the internal pterygoid plate
articulates with the posterior border of the vertical plate of the palate bone.
The recess between the two pterygoid plates posteriorly is subdivided. The
upper, smaller and shallower depression is the scaphoid fossa; it gives origin to
the tensor (circumflexus) palati. The lower, deeper and larger, is the pterygoid
fossa; it lodges the internal pterygoid and tensor palati muscles. The fossa is
completed by the tuberosity of the palate bone.
Articulations. The sphenoid articulates with the following bones: ethmoid,
frontal, parietal, temporal, epipteric, palate, vomer, occipital, malar, sphenoidal
turbinals, and occasionally with the maxilla.
Muscles. It gives origin to the following muscles :-
-
Temporal.
Internal pterygoid.
External pterygoid.
Tensor tympani.
External rectus of the eyeball.
Internal rectus
99
99
29
22
22
Tensor palati.
Superior rectus
Superior oblique
Levator palpebræ.
Ligaments. The sphenoid has numerous intrinsic ligaments which occasionally
ossify and produce adventitious foramina. Of these, the more important are:-
D 2

36
THE SKELETON
Inter-clinoid.-This passes from the anterior to the posterior clinoid processes.
Carotico-clinoid. From the anterior to the middle clinoid process. The ossifi-
cation of this ligament gives rise to a ring of bone through which the internal
carotid artery passes.
Pterygo-spinous.-This is attached to the spine of the sphenoid and the
external pterygoid plate near the upper third.
The spheno-mandibular ligament (long internal lateral ligament of the jaw).
Several other insignificant bands have received names, but they are of no
importance.
FIG. 40. THE UNDER SURFACE OF PRE-SPHENOID AT THE SIXTH YEAR.
LESSER WING
PRE-SPHENOID
PTERYGO-PALATINE GROOVE.
OPTIC FORAMEN
VIDIAN CANAL
VAGINAL PROCESS
biorcodge
Blood-supply.-The sphenoid is supplied by branches of the middle and small
meningeal arteries; also the anterior deep temporal and other branches of the
internal maxillary, such as the Vidian, pterygo-palatine and spheno-palatine.
The body of the bone also receives twigs from the internal carotid.
Ossification. The sphenoid is ossified in cartilage from twelve ossific nuclei
which appear in pairs. The nuclei are divisible into two sets,-those for the pre-
sphenoid, and those for the post-sphenoid.
The post-sphenoid centres consist of four pairs disposed as follows:-One for
each ali-sphenoid (great wing). A pair of median nuclei for the basi-sphenoid,
FIG. 41. THE SPHENOID AT BIRTH.
VIDIAN CANAL
LINGULA
and a nucleus for each lingula (sphenotic nucleus), and one for each internal
pterygoid. The external pterygoid is an outgrowth from the great wing.
The pre-sphenoid centres consist of a nucleus for each orbito-sphenoid (lesser
wings), and a median pair for the body of the pre-sphenoid. These nuclei appear
at intervals from the eighth week to the end of the third month in the following
order: ali-sphenoid, basi-sphenoid, lingulæ, internal pterygoids, orbito-sphenoid,
and pre-sphenoid. The various earthy spots fuse together, so as to form at birth
three pieces. The median piece consists of the basi-sphenoid and lingulæ, con-
joined with the pre-sphenoid carrying the lingulæ; the two lateral pieces are the

THE SPHENOID
37
ali-sphenoids (greater wings) carrying the internal pterygoid plates. The greater
wings are joined to the lingulæ by cartilage. The dorsum ephippii is cartilaginous
at birth. In the course of the first year the orbito-sphenoids fuse in the middle
FIG. 42. THE JUGUM SPHENOIDALE.
line to form the jugum sphenoidale, which excludes the anterior part of the pre-
sphenoid from the cranial cavity. The greater wings fuse with the lingulæ in the
course of the first year.
THE TEMPORAL BONES
The adult temporal bone consists of three parts, so firmly united as to afford
little trace of its complex origin. At birth the three parts are easily separable as
the squamosal, petrosal, and tympanic (fig. 103).
The squamosal resembles a large scale; it is attached at right angles to the
petrosal, and forms part of the side wall of the skull. It is thin, and in places
translucent. The outer surface is smooth and forms part of the temporal fossa;
it presents one, and occasionally two nearly vertical grooves for the deep temporal
FIG. 43. THE LEFT TEMPORAL BONE. (Outer view.)
ZYGOMA
ZYGOMATIC TUBERCLE
GLENOID FOSSA
GLASERIAN FISSURE
TYMPANIC PLATE
STYLOID PROCESS
adt 26
SQUAMOSAL
TEMPORAL FOSSA
POST-GLENOID TUBERCLE
AUDITORY MEATUS
MASTOID
PROCESS
AURICULAR FISSURE
arteries. A ridge of bone, the supra-mastoid crest, runs immediately above the
external auditory meatus, and is continued onwards to the zygoma.
The zygoma is a narrow projecting bar of bone, jutting forwards and lying
parallel with the squamosal. It has two surfaces and two borders. The outer
surface is subcutaneous; the inner looks towards the temporal fossa. The inner
surface and lower border give origin to the masseter muscle. The upper border
receives the temporal fascia. The tip of the zygoma is serrated for articulation

38
THE SKELETON
with the malar. Posteriorly the lower border ends in a tubercle, which is the
meeting point of two ridges; of these, the anterior passes inwards at right angles
to the zygoma, and expands into the articular eminence which serves as an
articular facet for the condyle of the mandible when the mouth is opened. The
second ridge runs backwards and forms the upper boundary of the glenoid fossa,
and curving downwards ends in a tubercle, the post-glenoid tubercle, immediately
anterior to the Glaserian fissure. The oval deep depression between these ridges
is the glenoid fossa, which receives the condyle of the mandible. This fossa is
limited posteriorly by the Glaserian fissure.
The inner surface of the squamosal presents furrows for the convolutions of
the brain and grooves for the middle meningeal arteries. The line of union between
the squamosal and petrosal is sometimes indicated by a persistent petro-squamosal
suture. Rarely the two portions remain permanently separate.
The superior border of the squamosal is thin, and bevelled on the cerebral
surface where it overlaps the parietal; anteriorly it is serrated for the posterior
border of the greater wing of the sphenoid. Posteriorly it joins the rough serrated
margin of the petrosal to form the parietal notch.
The petrosal element is a four-sided pyramid of very dense bone; its base is
FIG. 44. THE LEFT TEMPORAL BONE. (Inner view.)
FOR MIDDLE MENINGEAL ARTERY
LATERAL SINUS
THE GROOVE FOR SUPERIOR
PETROSAL SINUS
MASTOID FORAMEN
AQUEDUCTUS VESTIBULI
AQUEDUCTUS COCHLEA
SQUAMOSAL
REMNANT OF FLOCCULAR FOSSA
INTERNAL AUDITORY MEATUS
PETROSAL
FOR COCIPITAL
formed by the mastoid process; the apex is rough and forms part of the boundary
of the foramen lacerum medium. Two sides of the pyramid project into the cranial
cavity, of which one forms the posterior boundary of the middle fossa, and the other
the anterior boundary of the posterior fossa of the cranium. Of the two remaining
surfaces, one appears on the under surface of the skull, and the fourth constitutes
the inner wall of the recess called the tympanum.
The posterior surface is bounded above by the superior border, which serves for
the attachment of the tentorium cerebelli, and is grooved for the superior petrosal
sinus; near the apex, this border presents the trigeminal notch (converted into a
foramen by the tentorium) for the transmission of the trigeminal nerve. This
border in old skulls sometimes terminates in a spiculum of bone-the petro-sphe-
noidal process and extends to the dorsum ephippii, and completes a foramen
(petro-sphenoidal) which transmits the sixth nerve. Near the middle of the posterior
surface is an oblique inlet, the internal auditory meatus, which receives the
auditory and facial nerves and the auditory artery. The meatus is about 10 mm.
deep, and to be properly examined the surface of the bone should be cut away,
or the parts studied in the petrosal of a foetus at or near the ninth month, for it
is at this date relatively large and shallow.

THE TEMPORAL BONES
39
The fundus of the meatus is divided by a transverse ridge of bone, the falciform crest,
into a superior and inferior fossa. Of these, the superior is the smaller, and presents
anteriorly the beginning of the aqueduct of Fallopius; this transmits the seventh nerve.
The rest of the surface above the crest is dotted with small foramina (the superior
cribriform area) which transmit nerve-twigs to the fovea hemielliptica and the ampullæ
of the superior and external semicircular canals. Below the crest there are two depressions
and an opening. Of these, an anterior curled tract (the spiral cribriform tract) with a
central foramen (foramen centrale cochleare) marks the base of the cochlea; the central
foramen indicates the orifice of the canal of the modiolus, and the smaller foramina
transmit the cochlear twigs of the auditory nerve. The posterior opening (foramen
singulare) is for the nerve to the ampulla of the posterior semicircular canal. The middle
depression (middle cribriform area) is dotted with minute foramina for the nerve-twigs to
the saccule, which is lodged in the fovea hemispherica. The inferior fossa is subdivided
by a low vertical crest. The fossa in front of the crest is the fossula cochlearis, and the
recess behind it is the fossula vestibularis.
Behind the meatus is a small slit (large in the foetus) which formerly lodged
the aqueductus vestibuli (ductus endolymphaticus); in the adult it is occupied by
a small arteriole and venule and a process of dura mater. Occasionally a bristle
can be passed along this passage into the vestibule. Above, and anterior to this,
is a second slit also lodging a process of the dura mater. This is a remnant of the
FIG. 45. THE FORAMINA IN THE FUNDUS OF THE LEFT INTERNAL AUDITORY MEATUS
OF A CHILD AT BIRTH (4). (Diagrammatic:)
SUPERIOR FOSSA
SUPERIOR CRIBRIFORM AREA
MIDDLE CRIBRIFORM AREA
FORAMEN SINGULARE
ENTRANCE TO THE AQUEDUCT OF FALLOPIUS
FALCIFORM CREST
ORIFICE OF THE CANAL OF THE MODIOLUS
SPIRAL CRIBRIFORM TRACT
INFERIOR FOSSA
Posteriorly, this surface has a deep
floccular fossa, so conspicuous in the foetus.
groove for the lateral sinus.
The anterior face of the pyramid is separated from the squamosal by
the petro-squamous suture, which may persist throughout life. It presents the
following points of interest: near the apex it has a shallow depression for the
Gasserian ganglion, and the recess of dura mater (Meckel's cave) in which it lies;
below this is the termination of the carotid canal. Behind these are two small
foramina, overshadowed by a thin osseous lip. Of these, the larger and more
internal is the hiatus Fallopii, which transmits a small artery from the middle
meningeal and the greater petrosal nerve. The smaller and external foramen is
for the lesser petrosal nerve. Still more externally there is a thin translucent plate of
bone, the tegmen tympani. Behind, and slightly internal to this, there is a ridge
formed by the superior semicircular canal.
The inferior or basilar surface is very irregular, and has the following points
of interest. At the apex is a quadrilateral smooth space for the tensor tympani
and levator palati muscles. Behind this is the large circular orifice of the carotid
canal, for the transmission of the carotid artery and a plexus of sympathetic
nerves. Internal to this, near the inner border of the bone, is the orifice of the
aqueductus cochleæ (ductus perilymphaticus). In the adult it transmits a small
vein from the cochlea to the internal jugular. Posteriorly is the elliptical jugular
fossa with smooth walls for the ampulla which receives the lateral and in-
ferior petrosal sinuses, and forms the commencement of the internal jugular vein.

40
THE SKELETON
In the ridge of bone between the fossa and the carotid canal there is a small fora-
men, the tympanic canaliculus, for the tympanic branch of the glosso-pharyngeal
nerve. On the inner wall of the fossa a similar minute foramen, the auricular
canaliculus, permits the passage inwards of the auricular branch of the vagus nerve.
Behind the fossa is the rough jugular surface, which receives the jugular process
of the occipital. Firmly ankylosed to the inner surface of the tympanic plate is
the styloid process, varying in length from one to five cm. At its base is the stylo-
mastoid foramen, from which issues the facial nerve; the stylo-mastoid artery
enters the Fallopian canal through this opening. Running backwards from this
foramen are two grooves; the outer is the digastric groove, from which the digastric
muscle arises. The inner is narrower and shallower; it lodges the occipital
artery.
Of the outer surface, the only part which appears externally is the mastoid
process; the rest is occupied by a recess known as the tympanum. The mastoid
process is a nipple-shaped prominence of bone, formed partly by the squamosal, but
mainly by the petrosal. Its upper limit is the supra-mastoid crest. Below the
crest an irregular furrow crosses the surface of the process from the parietal notch
FIG. 46.-THE LEFT TEMPORAL BONE. (Inferior view.)
CAROTID CANAL
SURFACE FOR SPHENOID
Tensor tympani and
levator palati
TYMPANIC CANALICULUS
AQUEDUCTUS COCHLEA
AURICULAR CANALICULUS
JUGULAR FOSSA
JUGULAR SURFACE
STYLO-MASTOID FORAMEN
ARTICULATION FOR OCCIPITAL
-ARTICULAR EMINENCE
ZYGOMATIC TUBERCLE
GLASERIAN FISSURE
Y STYLOID PROCESS
EXTERNAL AUDITORY MEATUS
AURICULAR FISSURE
MASTOID PROCESS
DIGASTRIC GROOVE, sinon
OCCIPITAL GROOVE
of voorg
anont
So
downwards, to the middle of the meatus. This furrow (squamo-mastoid) is often
dotted with holes, and represents the line of union of squamosal and petrosal.
The mastoid process gives attachment to the sterno-mastoid, splenius capitis,
trachelo-mastoid, occipito-frontalis, and retrahens aurem muscles.o
The tympanum is hidden by the tympanic plate, which extends downwards
from the Glaserian fissure to form the vaginal process. Anteriorly it extends
forwards and ankyloses with the outer wall of the carotid canal. The Glaserian
fissure separates it from the squamosal. This fissure transmits the tympanic
branch of the internal maxillary artery, and lodges the slender process of the
malleus. A narrow subdivision of this fissure, canal of Huguier, is traversed by
the chorda tympani nerve. The tympanic plate forms the anterior, lower, and
part of the posterior walls of the external auditory meatus. It is limited
posteriorly by the auricular fissure, through which the auricular twig of the vagus
nerve issues.
The external auditory meatus assumes the form of an elliptical bony tube. Its
outer margin is rough and gives attachment to the cartilaginous portion of the pinna.
Between the posterior edge of the meatus and the mastoid process is the auricular

THE TEMPORAL BONES
41
fissure. The tympanic orifice of the meatus is smooth, and presents a well-marked
groove for the tympanic membrane. This is very conspicuous in young bones.
The direction of the meatus is somewhat oblique. In children, and occasionally in
adults, a circular opening exists in the anterior wall of the meatus (fig. 53).
FIG. 47.-TEMPORAL BONE WITH MUSCLE ATTACHMENTS.
-Temporal
·
Masseter
TYMPANIC PLATE
Stylo-glossus Stylo-pharyngeus
Stylo-hyoid
Retrahens aurem
Occipito-frontalis
Sterno-mastoid
-Trachelo-mastoid
Splenius capitis
Articulations. The temporal bone articulates with the occipital, parietal,
sphenoid, malar, and by a movable joint with the mandible. Occasionally the
squamosal presents a process which articulates with the frontal. A fronto-
squamosal suture is common in the skulls of the lower races of men, and is
normal in the skulls of the chimpanzee, gorilla, and gibbon.
The muscles connected with the temporal bone are:-
To the mastoid process
To the styloid process.
To the zygoma
Intrinsic muscles
To the petrosal.
Sterno-mastoid.
Splenius capitis.
Trachelo-mastoid.
Digastric.
Occipito-frontalis.
Attrahens aurem.
Retrahens aurem.
Attollens aurem.
Stylo-glossus.
Stylo-hyoid.
Stylo-pharyngeus.
Masseter.
Stapedius.
Tensor tympani.
Levator palati.
Ligaments:-
Capsular
Interarticular
Internal lateral
External lateral
of temporo-mandi-
bular joint.
Stylo-hyoid.
Stylo-maxillary.
Petro-sphenoidal.

42
THE SKELETON
Ligaments connected with the ear-bones :-
Anterior ligament of malleus (laxator tympani).
External ligament of malleus.
Superior ligament of malleus.
Ligament of incus.
The blood-supply.-Arteries supplying the temporal bone are derived from
various sources. The chief are:-
Stylo-mastoid from posterior auricular: it enters the stylo-mastoid foramen.
Tympanic from internal maxillary: it passes through the Glaserian fissure.
Petrosal from middle meningeal: transmitted by the hiatus Fallopii.
Tympanic from internal carotid whilst in the carotid canal.
Auditory from the basilar: it enters the internal auditory meatus, and is distri-
buted to the cochlea, vestibule, &c.
Other less important twigs are furnished by the middle meningeal, the menin-
geal branches of the occipital, and by the ascending pharyngeal artery. The
squamosal is supplied on its internal face by the middle meningeal, and externally
by the branches of the deep temporal from the internal maxillary.
THE TYMPANUM
The tympanum is an irregular cavity in the temporal bone. At birth it is a
recess in the outer wall of the petrosal, partially closed externally by the squamosal.
When the various elements of the temporal bone coalesce, and the tympanic
plate becomes fully developed, then the cavity is completely surrounded by bony
walls, except where it communicates with the external auditory meatus.
The roof, or tegmen tympani, is a translucent plate of bone belonging to
the petrosal; it separates the tympanum from the middle fossa of the skull. The
floor is the plate of bone which forms the roof of the jugular fossa.
The inner wall is formed by the external surface of the petrosal bone, and presents
the following points for study:-In the angle between it and the roof is a horizontal
ridge which extends backwards as far as the posterior wall, and then turns down-
wards in the angle between the inner and posterior wall. This is the Fallopian
canal; it is occupied by the facial nerve (seventh). Near the roof, but below the
Fallopian canal, is the fenestra ovalis, which leads into the vestibule: this fenestra
receives the base of the stapes. Below the fenestra ovalis is the promontory,
which contains the commencement of the first turn of the cochlea. In the lower
and posterior part of the promontory is the fenestra rotunda; this, in the recent
state, is closed by the secondary membrane of the tympanum. In the macerated
bone it leads into the spiral canal of the cochlea. The promontory is also
furrowed by some delicate channels (sometimes canals) for the tympanic branch of
the glosso-pharyngeal nerve, which enters the tympanum through the tympanic
canaliculus. The posterior wall of the tympanum is formed by the mastoid
process. At the superior and internal angle of this wall an opening leads into the
mastoid antrum. Immediately below this opening there is a small hollow cone, the
posterior pyramid; its cavity is continuous with the descending limb of the
Fallopian canal. One or more bony spiculæ often connect the apex of the pyramid
with the promontory. The cavity of this cone is occupied by the stapedius
and the tendon of the muscle emerges at the apex.
The roof and floor converge towards the anterior extremity of the tympanum,
which is, in consequence, very narrow, and occupied by two canals: the lower for
the Eustachian tube, the upper for the tensor tympani muscle. These grooves are

THE TYMPANUM
43
sometimes described together as the canalis musculo-tubarius. In carefully prepared
bones the upper canal is a small horizontal hollow cone (anterior pyramid), 12 mm.
in length, which lodges the tensor tympani muscle; the apex is just in front of the
fenestra ovalis, and is perforated to permit the passage of the tendon of the muscle.
As a rule the thin walls of the canal are damaged, and represented merely by a thin
ridge of bone. The posterior portion of this ridge projects into the tympanum, and
is known as the processus cochleariformis. The thin septum between the canal
for the tensor tympani and the tube is pierced by a narrow canal which is traversed
by the small deep petrosal nerve. The outer wall is occupied mainly by the external
auditory meatus. This opening is closed in the recent state by the tympanic
membrane. The rim of bone to which the membrane is attached is incomplete
above; the defect is known as the notch of Rivinus. Anterior to this notch, in
the angle between the squamosal and the tympanic plate, is the Glaserian fissure,
and the small passage which transmits the chorda tympani nerve sometimes called
the canal of Huguier.
The tympanic cavity may be divided into three parts. The part below the level
of the superior margin of the external auditory meatus is the tympanum proper;
CAROTID CANAL
Tensor Tympani
GROOVE FOR
EUSTACHIAN TUBE
Levator Palati
CANAL FOR SMALL DEEP
PETROSAL NERVE
FIG. 48.-THE INNER WALL OF TYMPANUM.
Stylo-pharyngeus
Stylo-hyoid
Stylo-glossus
EXTERNAL SEMICIRCULAR
CANAL
MASTOID ANTRUM
-FALLOPIAN CANAL
ITER CHORDÆ POSTERIUS
STYLO-MASTOID FORAMEN
the portion above this level is the attic of the tympanum; it receives the head of
the malleus, the body of the incus, and leads posteriorly into a recess known as the
mastoid antrum.
The mastoid antrum.-This is quite distinct from the mastoid cells. It is an
air-chamber communicating with the attic of the tympanum. It is separated from
the middle cranial fossa by the posterior portion of the tegmen tympani; the floor
is formed by the mastoid portion of the petrosal; it communicates with the
mastoid cells. The outer wall is formed by the squamosal below the supra-mastoid
crest. In children the outer wall is exceedingly thin, but in the adult it is of
considerable thickness. The external semicircular canal projects into the antrum
on its inner wall, and is very conspicuous in the fœtus.
A canal occasionally leads from the mastoid antrum through the petrous bone to open
in the recess which indicates the position of the floccular fossa; it is termed the petro-
mastoid canal. (Gruber.)
The Fallopian canal.-This canal begins at the anterior angle of the superior
fossa of the internal auditory meatus, and passes directly outwards to the hiatus
Fallopii; it then turns abruptly backwards and forms a horizontal ridge on the
inner wall of the tympanum lying in the angle between it and the tegmen
tympani. It passes immediately above the fenestra ovalis, and extends as far
backwards as the entrance to the mastoid antrum; here it comes into contact with
44
THE SKELETON

the inferior aspect of the projection formed by the external semicircular canal. It
then turns vertically downwards, running in the angle between the internal and
posterior wall of the tympanum to terminate at the stylo-mastoid foramen.
The canal is traversed by the facial (seventh) nerve. Numerous openings exist
in the walls of this passage. At the hiatus the greater and smaller superficial
petrosal nerves escape from, and a branch from the middle meningeal artery enters,
the canal. In the vertical part of its course the cavity of the posterior pyramid
opens into it. There is also a small orifice by which the auricular branch of the
vagus joins the facial, and near its termination the iter chorda posterius for the
chorda tympani nerve leads from it into the tympanum.
The vestibule.-This is an oval chamber situated between the base of the
internal auditory meatus and the inner wall of the tympanum, with which it
communicates by way of the fenestra ovalis. Anteriorly the vestibule leads into
the cochlea, and posteriorly it receives the extremities of the semicircular canals.
It measures about 3 mm. transversely, and is somewhat longer antero-posteriorly.
Its inner wall presents at the anterior part a circular depression, the fovea
hemispherica, which is finely perforated for the passage of nerve-twigs. This
fovea is separated by a vertical ridge (the crista vestibuli) from the vestibular
orifice of the aqueductus vestibuli (ductus endolymphaticus), which passes obliquely
backwards to open on the posterior surface of the petrosal bone.
FIG. 49.-THE LEFT OSSEOUS LABYRINTH. (After Henle. From a cast.)

THE COCHLEA
SUPERIOR SEMICIRCULAR CANAL
EXTERNAL SEMICIRCULAR CANAL
POSTERIOR SEMICIRCULAR CANAL
FENESTRA ROTUNDA OR COCHLEA
FENESTRA OVALIS OR VESTIBULI
The roof contains an oval depression-the fovea hemielliptica.
Anteriorly
the vestibule leads into the cochlea. Posteriorly it receives the five openings of
the semicircular canals.
The semicircular canals are three in number. Each forms about two-thirds
of a circle; they lie in different planes. One extremity of each canal is dilated to
form an ampulla.
The superior canal lies transversely to the long axis of the petrosal, and is
nearly vertical; its highest limb makes a projection on the anterior surface of the
bone. The ampulla is at the outer end; the inner end opens into the vestibule
conjointly with the superior limb of the posterior canal.
The posterior canal is nearly vertical and lies antero-posteriorly. It is the
longest of the three; its upper extremity joins the inner limb of the superior
canal, and opens in common with it into the vestibule. The lower is the ampul-
lated end.
The external canal is placed horizontally and arches outwards; its external
limb forms a prominence in the mastoid antrum. This canal is the shortest; its
ampulla is at the outer end near the fenestra ovalis.
The cochlea. This is a cone-shaped cavity lying with its base upon the internal
auditory meatus, and the apex directed outwards. It measures about five millimetres
in length, and the diameter of its base is about the same. The centre of this
cavity is occupied by a column of bone-the modiolus-around which a delicate
bony lamella appears to be wound. This lamella is the osseous spiral lamina,



THE TYMPANUM
45
which gives attachment to the structures which form collectively the membranous
cochlea. The lamina makes two and a half turns in all. The first turn is the
largest, and forms a bulging, the promontory, on the inner wall of the tympanum.
The lamina terminates at the apex of the cochlea in a hooklike process-the
hamulus.
The modiolus is traversed by a central canal, and presents many canaliculi for
the transmission of the twigs of the cochlear division of the auditory nerve. There
FIG. 50. THE COCHLEA IN SAGGITAL SECTION. (After Henle.)
INTERNAL AUDITORY MEATUS
THE SPIRAL CANAL
is also a canal which winds round the modiolus at the base of the spiral lamina,
known as the spiral canal of the modiolus.
The portion of the cochlea above the lamina is the scala vestibuli; the part
below, that is, on the basal aspect of the lamina, is the scala tympani; it opens
into the tympanum by way of the fenestra rotunda. Near the commencement of
the scala tympani, and close to the fenestra rotunda, is the cochlear orifice of the
aqueductus cochleæ (ductus perilymphaticus). In the adult this opens on the
inferior surface of the petrosal near the apex, and transmits a small vein from the
cochlea to the jugular fossa.
Measurements of the principal parts connected with the auditory organs :-
Internal auditory meatus
External auditory meatus
Tympanum.
Length of anterior wall, 13-14 mm.
99
posterior wall, 6.7 mm.
14-16 mm. (Gruber.)
Length, 13 mm.
Height in centre of cavity, 15 mm.
Width opposite the membrana tympani, 2 mm.
99
tubal orifice, 3-4 mm.
(Von Tröltsch.)
The capsule of the osseous labyrinth is in length 22 mm. (Schwalbe.)
Superior semicircular canal measures along its convexity 20 mm.
The posterior
99
99
29
The external
29
99
22 mm.
99
99
15 mm.
99
99
The canal is in diameter 1.5 mm. (Huschke.)
The ampulla of the canal, 2.5 mm.
The Ossification of the Temporal Bone
At birth the temporal bone consists of three parts easily separable in the macerated
skull: they are the petrosal, squamosal, and the tympanic. (The styloid process is car-
tilaginous with the exception of its basal element, the tympano-hyal, which, with the
ear-bones, will be described with the appendicular elements of the cranium.
The squamosal and tympanic bones develop in membrane. The squamosal is formed
from one centre, which appears as early as the eighth week. Ossification extends into the
zygoma, which grows concurrently with the squamosal. At first the tympanic border is

46
THE SKELETON
nearly straight, but soon assumes its characteristic horseshoe shape. At birth the post-
glenoid tubercle is conspicuous, and at the hinder end of the squamosal there is a recess
where it comes into relation with the mastoid antrum. The centre appears for the
tympanic bone about the twelfth week. At birth it is a horseshoe-shaped ossicle slightly
FIG. 51.-THE TEMPORAL BONE AT BIRTH. (Outer view.)
POST-GLENOID TUBERCLE-
GLASERIAN FISSURE-
TYMPANIC FISSURE
SQUAMOSAL
-PETRC-SQUAMOUS SUTURE
-PETROSAL
-STYLO-MASTOID FORAMEN
TYMPANO-HYAL
CAROTID CANAL
FIG. 52.-TEMPORAL BONE AT BIRTH. (Inner view.)
abain sahler Lauss a odio si
HIATUS FALLOPII
FLOCCULAR FOSSA
-AQUEDUCTUS VESTIBULI
INTERNAL AUDITORY MEATUS
FIG. 53. TEMPORAL BONE AT THE SIXTH YEAR.
AUDITORY MEATUS
OPENING IN THE TYMPANIC PLATE
GLASERIAN FISSURE
weled
WORMIAN BONE
IN THE
PARIETAL NOTCH
ankylosed to the lower border of the squamosal; the open arms being directed upwards.
The tip of the anterior arm terminates in a small irregular process, and the inner aspect
presents, in the lower half of its circumference, a groove for the reception of the tympanic
membrane.
Up to the middle of the fifth month the periotic capsule is cartilaginous; it then

THE TYMPANUM
47
ossifies so rapidly that by the end of the sixth month its chief portion is converted into
porous bone. The ossific material is deposited in four centres, or groups of centres, named
according to their relation to the ear-capsule in its embryonic position.
The nuclei are deposited in the following order :-
1. The opisthotic appears at the end of the fifth month. The osseous material is seen
first on the promontory, and it quickly surrounds the fenestra rotunda from above down-
wards, and forms the floor of the vestibule, the lower part of the fenestra ovalis, and the
internal auditory meatus, it also invests the cochlea. Subsequently a plate of bone arises
from it to surround the internal carotid artery and form the floor of the tympanum.
FIG. 54.-THE MASTOID ANTRUM AT THE THIRD YEAR. (After Symington.)
MASTOID ANTRUM
VESTIBULE
LATERAL SINUS
2. The pro-otic nucleus is deposited behind the internal auditory meatus near the inner
limb of the superior semicircular canal. It covers in a part of the cochlea, the vestibule,
and the internal auditory meatus, completes the fenestra ovalis, and invests the superior
semicircular canal.
3. The pterotic nucleus ossifies the tegmen tympani and covers in the external semi-
circular canal; the ossific matter is first deposited over the outer limb of this canal.
4. The epiotic is the last to appear, and is first seen at the most posterior part of the
posterior semicircular canal; often it is double. This centre gives rise to the mastoid
process.
FIG. 55. THE MASTOID ANTRUM AT THE NINTH YEAR. (After Symington.)
MASTOID ANTRUM
POSTERIOR SEMI-
CIRCULAR CANAL
LATERAL SINUS.
Digastric
At birth the bone is of loose and open texture, resembling biscuit or unglazed porcelain,
thus offering a striking contrast to the dense and ivory-like petrosal of the adult. It
also differs from the adult bone in several other particulars. The floccular fossa is
widely open and conspicuous. Voltolini has pointed out that a small canal leads from
the floor of the floccular fossa and opens posteriorly on the mastoid surface of the bone;
it may open in the mastoid antrum. The hiatus Fallopii is unclosed, and the tympanic
recess is filled with gelatinous connective tissue. The mastoid process is not developed,
and the jugular fossa is a shallow depression.
After birth the parts grow rapidly. The tympanum becomes permeated with air; the

48
THE SKELETON
various elements fuse; and the tympanic annulus grows rapidly and forms the tympanic
plate. Growth in the tympanic bone takes place most rapidly from the tubercles at its
upper extremities, and in consequence of the slow growth of the lower segment a
deep notch is formed; gradually the tubercles coalesce, leaving a foramen in the anterior
part of the bony meatus which persists until puberty, and even in the adult. In most
skulls a cleft capable of receiving the nail remains between the tympanic element and the
mastoid process; this is the auricular fissure. The anterior portion of the tympanic plate
forms with the inferior border of the squamosal a cleft known as the Glaserian fissure,
which is subsequently encroached upon by the growth of the petrosal. As the tympanic
plate increases in size it joins the outer wall of the carotid canal and presents a prominent
lower edge, known as the vaginal process.
FIG. 56. THE MASTOID ANTRUM OF AN ADULT. (After Symington.)
MASTOID ANTRUM
SEMICIRCULAR CANALS
LATERAL SINUS
AIR CELLS OF MASTOID
The mastoid process becomes distinct about the first year, coincident with the ob-
literation of the petro-squamous suture. It increases in thickness by deposit from the
periosteum. Towards puberty, rarely earlier, the process becomes pneumatic, the air-
cells being lined by delicate mucous membrane. In old skulls the air-cells may extend
into the jugular process of the occipital bone.
At birth the mastoid antrum is relatively large and bounded externally by a thin plate
of bone belonging to the squamosal. As the mastoid increases in thickness the antrum
comes to lie at a greater depth from the surface and becomes relatively smaller.
The size of the antrum and the variations in thickness of its outer wall at the age of
three years, nine years, and in the adult, are shown in figs. 54, 55 and 56. In each case
the sections were made slightly posterior to the external auditory meatus. In 20 per cent.
of skulls there are no air-cells in the mastoid process.
THE PARIETAL
The two parietals form a large portion of the vault and sides of the skull;
they are interposed between the frontal anteriorly and the occipital posteriorly.
Each parietal presents two surfaces, four borders, and four angles. The external
surface is convex and smooth: the convexity, best marked in young bones, is
greatest near the centre, which is termed the parietal eminence. Crossing the
middle of the bone are the two temporal ridges; the lower is the better marked,
and limits the origin of the temporal muscle. The upper ridge is less constant, and
it gives attachment to the temporal fascia. The internal surface is concave and
marked with depressions corresponding to the cerebral convolutions. Numerous
vertical deep furrows for the branches of the middle meningeal artery radiate from
the anterior inferior angle and lower border of the bone. Along the superior margin
of the bone there is a groove which, when articulated with the opposite bone,
forms a furrow which receives the superior longitudinal sinus. In adult bones

THE PARIETALS
49
FIG. 57. THE LEFT PARIETAL. (Outer surface.)
SUPERIOR BORDER
PORTION COVERED
BY APONEUROSIS
OF OCCIPITO-
FRONTALIS
PARIETAL EMINENCE
SUPERIOR TEMPORAL
RIDGE
INFERIOR TEMPORAL
RIDGE
FOR TEMPORAL
MUSCLE, AND
FORMS PART OF
THE TEMPORAL
FOSSA
ANTERIOR INFERIOR
ANGLE
PARIETAL FORAMEN
FIG. 58. THE LEFT PARIETAL. (Inner surface.)
GROOVE FOR SUPERIOR LONGITUDINAL SINUS
PARIETAL FORAMEN
GROOVE FOR LATERAL SINUS GROOVES FOR MIDDLE MENINGEAL ARTERY
DEPRESSIONS FOR PACCHIONIAN BODIES
paci
Lon
E
50
THE SKELETON

numerous deep circular depressions for Pacchionian bodies are found near this
groove. The superior border is deeply serrated for the opposite parietal, the union
with which forms the sagittal suture. The anterior and posterior borders are
deeply serrated: the anterior articulates with the frontal to form the coronal,
and the posterior with the squamo-occipital to form the lambdoid sutures. The
inferior border is bevelled and overlapped by the squamosal to form the squamous
suture. Of the angles, the anterior inferior is prolonged downwards and articulates
with the summit of the greater wing of the sphenoid. The posterior inferior angle
articulates with the mastoid portion of the petrosal; on its inner surface it has a
horizontal groove for lodging a portion of the lateral sinus. The superior angles
present nothing worthy of note.
Articulations. The parietal articulates with its fellow, the occipital, squamosal,
frontal, sphenoid, and epipteric bones. Occasionally the squamosal and epipteric
may exclude the parietal from union with the greater wing of the sphenoid.
Blood-supply. From the middle meningeal, occipital, and supraorbital arteries.
Ossification. The parietal ossifies from an earthy spot deposited in the outer
layer of the dura mater about the seventh week. This bone is sometimes divided
by a horizontal suture.
THE FRONTAL
This bone bears much the same relation to the anterior part of the skull
that the occipital bears to the posterior. It has, not inaptly, been compared to a
cockle shell. The inner or posterior surface is concave, forming a deep fossa for
the reception of the frontal lobes of the cerebrum. There is a gap in the lower
part of the bone known as the ethmoidal notch, which overlaps by its thin edges
the cribriform plate of the ethmoid and forms, with that bone, the internal orifices
of the anterior and posterior ethmoidal canals. The anterior part of this notch
articulates with the crista galli, and the small hole in the line of suture is the
foramen cæcum. Prolonged vertically upwards from the point of union with the
crista is a ridge of bone, which gradually opens out to form a furrow for the
reception of the superior longitudinal sinus; the ridge serves for the attachment
of the anterior part of the falx cerebri. The thin laminæ of bone on each side
of the ethmoidal notch are termed orbital plates, because they form the greater
part of the roof of each orbit. As a rule, they present deep depressions for the
convolutions on the orbital surface of the cerebrum. The rest of the cerebral
surface of the frontal is fairly smooth, and presents a few furrows for meningeal
arteries, and, near the median groove, pits for Pacchionian bodies.
The external surface is convex and smooth, often divided by an imperfect
fissure, the remains of the metopic suture, which indicates the line of union of the
two bones representing the frontal in early life. On each side of this suture a little
below the centre is the frontal eminence. Below the eminences, separated by
shallow grooves, are the two converging superciliary ridges, which approach each
other in the median line to form the nasal eminence. The smooth space bounded
by the converging superciliary ridges is the glabella. Below these ridges the bone
presents the sharp supraorbital ridges which end internally at the internal
angular, and externally at the external angular processes. Each ridge has a
narrow, deep supraorbital notch (sometimes a complete foramen) at its inner third.
At the bottom of this notch or foramen a small opening communicates with the
diploë. The external angular processes are prominent and articulate with the
malar bones; from each process a ridge extends upwards and backwards, marking
off the lateral aspect of the bone, where it assists in the formation of the temporal
ridge and fossa. The internal angular processes articulate with the lachrymal


THE FRONTAL
51
bones, and are separated by a serrated interval, the nasal notch, which receives the
upper borders of the nasal bones, and outside these the nasal processes of the
maxillæ. The notch has in the middle a long pointed process, the nasal spine,
which lies between the upper part of the nasal bones and the mesethmoid. On
each side of the spine an opening leads into the large frontal sinuses.
FIG. 59. THE FRONTAL. (Anterior view.)
FRONTAL
EMINENCE
METOPIC SUTURE
SUPERCILLIARY RIDGE
TEMPORAL RIDGE
SUPRAORBITAL NOTCH
EXTERNAL ANGULAR
PROCESS
INTERNAL ANGULAR PROCESS
NASAL SPINE
The under surfaces of the orbital plates are smooth and concave; they form the
roofs of the orbits. Each is sharply limited anteriorly by the supraorbital ridge,
and presents at the outer angle the lachrymal fossa for the reception of the
FIG. 60. THE FRONTAL BONE. (Inferior view.)
ARTICULATION WITH NASAL BONE
WITH MAXILLA
WITH LACHRYMAL
39
WITH OS PLANUM
WITH MALAR
NASAL SPINE
TROCHLEAR
FOSSA
LACHRYMAL
FOSSA
ORBITAL
SURFACE
,, WITH GREATER WING-
OF SPHENOID
WITH LESSER WING
OF SPHENOID
LOT
ETHMOIDAL
NOTCH
lachrymal gland. Near the internal angle there is the small shallow supra-
trochlear fossa for the pulley of the superior oblique muscle. A sharp ridge runs
backwards from the internal angular process, and articulates successively with the
lachrymal and the os planum of the ethmoid. It has two notches, which are
converted into the anterior and posterior ethmoidal canals by articulation with the
E 2

52
THE SKELETON
os planum. The posterior border of each orbital plate articulates with the lesser
wing of the sphenoid (orbito-sphenoid), and is continuous with a rough triangular
surface for the greater wing (ali-sphenoid). This triangular surface is continuous
anteriorly with the serrated malar ridge of the sphenoid, and, laterally, with that
border of the bone which articulates with the parietals to form the coronal suture.
Between the ethmoidal notch and the inner margin of the orbital surface there
is an irregular surface which forms the roofs of the ethmoidal cells.
Articulations. The frontal articulates with the parietal, sphenoid, ethmoid,
lachrymal, malar, maxilla, and nasal bones. With the epipterics when present,
and occasionally (as explained on page 41) with the squamosal, and with the
sphenoidal turbinal when it creeps into the orbit.
It has the following muscles attached to it :-
Corrugator supercilii.
Temporal.
Occipito-frontalis.
Orbicularis palpebrarum.
The blood-supply.-Arterial twigs derived from the middle and small meningeal
arteries enter it on the cerebral, and branches from the frontal and supraorbital
arteries on the outer surface. The horizontal plate derives twigs from the
ethmoidal and other branches of the ophthalmic artery.
FIG. 61. THE FRONTAL BONE AT BIRTH.
ences.
Ossification. The frontal develops from two earthy spots deposited in the outer
layer of the dura mater, in the situations ultimately known as the frontal emin-
These nuclei appear about the eighth week, and quickly spread through the
membrane. At birth the bones are quite distinct. Subsequently they articulate
with each other in the median line to form the metopic suture. In a few cases the
bones remain distinct throughout life. In the majority of cases the suture is
obliterated; ankylosis commences about the sixth year. In adult skulls, traces
of the metopic suture may often be seen in the region of the glabella.
After the two halves of the bone have united, osseous material is deposited at
the lower end of the metopic suture to form the nasal spine, which is one of the
distinguishing features of the human frontal bone. The spine appears about the
twelfth year, and soon consolidates with the bone above. Accessory nuclei are
sometimes seen between this bone and the lachrymal; they may persist as Wormian
ossicles.
The frontal sinuses appear about the seventh year as prolongations from the
anterior ethmoidal cells. Occasionally they invade the horizontal plate, and
extend over the roof of the orbit.

THE ETHMOID
53
THE EPIPTERIC AND WORMIAN BONES
These are bones of variable size which occupy the anterior lateral fontanelles,
regions indicated in the adult skull by the name pterion. Each epipteric bone is
wedged between the squamosal, frontal, greater wing of sphenoid, and the parietal,
and is present in most skulls between the second and fifteenth year. After that
date it may persist as a separate ossicle, or unite with the frontal or the squamosal.
In this case it will cause a fronto-squamosal suture, and exclude the parietal
from the sphenoid. More commonly the epipteric joins the sphenoid. In some
skulls it is scarcely as large as a split pea, in others it is as broad as the thumb-
nail. The epipteric bone is pre-formed in membrane, and appears in the course of
the first year.
The Wormian bones are small, irregular-shaped ossicles, often found in the
sutures of the skull, especially those in relation with the parietal bones. Wormian
bones sometimes occur in great number; as many as a hundred have been counted
in one skull. They are rarely present in the facial sutures.
THE ETHMOID
The ethmoid is a bone of delicate texture, situated at the anterior part of the
skull-base; it is roughly cuboidal in shape, and its delicacy is due to the fact that
it is honeycombed by air-cells. The bone consists of four parts: the horizontal or
cribriform plate, two lateral masses, and a perpendicular plate.
The cribriform plate forms part of the anterior cerebral fossa, and is received
FIG. 62.-SECTION THROUGH THE NASAL FOSSA TO SHOW THE MESETHMOID.
CREST OF SPHENOID:
CRISTA GALLI
NASAL SPINE OF FRONTAL
MESETHMOID
GROOVE FOR NASAL NERVE;
VOMER
CREST OF PALATE BONE
SPINE OF PALATE BONE-
CREST OF MAXILLA
into the ethmoidal notch of the frontal bone. Standing vertically upon this plate is
the crista galli. To the posterior border of the crista the falx cerebri is attached;
this border divides posteriorly to enclose the ethmoidal spine of the sphenoid. The
anterior aspect of the base of the crista constitutes the anterior border of the
cribriform plate; it is rough for articulation with the frontal. In the suture
between the two bones there is an opening, the foramen cæcum, which trans-
mits a small vein. On each side of the crista galli the cribriform plate lodges the

54
THE SKELETON
olfactory bulb, and is perforated for the transmission of the filaments of the
olfactory nerves. On each side, near the anterior part of the crista, there is a
narrow longitudinal slit for the nasal branch of the fifth nerve.
The perpendicular plate (mesethmoid) is directly continuous with the crista
on the under aspect of the cribriform plate. It is a lamella of bone, trapezoid in
shape, which forms the upper part of the nasal septum; usually it is laterally
deflected. Its anterior border articulates with the nasal spine of the frontal, and
the crest of the nasal bones. The inferior border has the triangular cartilage
attached to it. The posterior border is subdivided: the upper half articulates with
the crest of the sphenoid, and the lower articulates with the vomer. The surfaces
of this plate present, especially in their upper parts, numerous foramina for vessels,
and grooves for filaments of the olfactory nerves.
The lateral mass, or labyrinth, of the ethmoid consists of two scroll-like
pieces of bone, the superior and inferior turbinals (ethmo-turbinals); a smooth,
quadrilateral plate of bone, the os planum, and a number of air-cells.
The os planum is on the outer side of the lateral mass, and forms a large por-
FIG. 63. THE ETHMOID. (Side view.)
CRISTA GALLI
POSTERIOR ETHMOIDAL
ANTERIOR ETHMOIDAL
GROOVE
GROOVE
OS PLANUM
UNCIFORM PROCESS-
INFERIOR TURBINAL
artolisdito od
SPHENOIDAL TURBINAL
MIDDLE TURBINAL
tion of the inner wall of the orbit. By the anterior border it articulates with the
lachrymal, by the posterior border with the sphenoid and the orbital process of the
palate bone; the inferior border articulates with the inner margin of the orbital
plate of the maxilla, and by the superior border with the horizontal plate of the
frontal. Two notches in the superior border lead into grooves running horizontally
across the lateral masses to the cribriform plate. These ethmoidal grooves are
converted into canals by the frontal bone. The anterior canal transmits the
anterior ethmoidal artery and nasal nerve; the posterior is for the posterior
ethmoidal artery.
The turbinals project on the inner aspect of the lateral mass; they coalesce
anteriorly, but are separated posteriorly by a space, termed the superior meatus.
Each turbinal has an attached upper, and a free, slightly convoluted, lower border.
In the recent state they are covered with mucous membrane, and present numerous
foramina for blood-vessels, and grooves for twigs of the olfactory nerves.
On the under surface of each lateral mass, near the anterior corner of the os
planum, an irregular lamina of bone projects downwards and backwards. This is
the unciform process: it articulates with the ethmoidal process of the inferior
turbinal, and forms a small part of the inner wall of the antrum.

THE ETHMOID
55
The ethmoidal cells occupy the space between the os planum and the turbinals;
they are divided by a thin septum into an anterior and posterior set. The cells
are imperfect in the ethmoid, they require the juxtaposition of other bones to make
them complete. Above, they are closed by the horizontal plate of the frontal,
posteriorly by the sphenoidal turbinal and the orbital process of the palate, inferiorly
by the maxilla, and anteriorly by the lachrymal. The anterior set communicate
with the frontal cells above, whilst below they open into the middle meatus of the
nose by a sinuous canal, the infundibulum. The posterior cells open into the
superior meatus, and occasionally communicate with the sphenoidal cells.
The cells are sometimes divided into groups, according to the bone which
lies in immediate juxtaposition. Those along the superior edge are the fronto-
ethmoidal; those beneath the lachrymal, lachrymo-ethmoidal, usually two in
number. Those along the lower edge are the maxillo-ethmoidal; and posteriorly
there are the spheno-ethmoidal, completed by the sphenoidal-turbinals, and a
palato-ethmoidal cell.
Articulations.-The ethmoid articulates with the frontal, sphenoid, two palate
FIG. 64. SECTION THROUGH THE NASAL FOSSA TO SHOW THE LATERAL MASS
OF THE ETHMOID.
BODY OF SPHENOID
SPHENOIDAL SINUS
SPHENO-PALATINE FORAMEN
MIDDLE MEATUS
INTERNAL PTERYGOID PLATE-
PALATE BONE
CRISTA GALLI
FRONTAL SINUS
SUPERIOR TURBINAL
MIDDLE TURBINAL
INFUNDIBULUM
INFERIOR TURBINAL
INTERIOR NASAL SPINE
ANTERIOR PALATINE FORAMEN
bones, two nasals, vomer, two inferior turbinals, the sphenoidal turbinals, two
maxillæ, and two lachrymal bones. The hinder surface of each lateral mass comes
into relation with the sphenoid on each side of the crest and rostrum, and helps to
close in the sphenoidal sinus.
Blood-supply. The anterior and posterior ethmoidal, and from the nasal
or spheno-palatine branch of the internal maxillary.
--
Ossification. The ethmoid has three centres of ossification. Of these, a
nucleus appears in the fourth month of intra-uterine life in each lateral cartilage.
At birth this bone is represented by two scroll-like bones, very delicate, and covered
with irregular depressions, which give it a worm-eaten appearance. Six months
after birth a nucleus appears in the ethmo-vomerine plate for the mesethmoid.
This gradually extends into the crista galli. During the third year the lateral
masses and the mesethmoid (perpendicular plate) ankylose. The cribriform plate
is derived from the lateral masses.
and they
The ethmoidal cells do not make their appearance before the third year,
gradually produce attenuation of the lateral masses. In many places there is

56
THE SKELETON
so much absorption of bone that the cells perforate the ethmoid in situations where
it is overlapped by other bones. Along the lower border of the bone, near its articula-
tion with the maxilla, the absorption leads to the partial detachment of a narrow
strip known as the uncinate or uneiform process. Sometimes a second but smaller
hook-like process is formed, above and anterior to the large one. This process is
so very fragile that it is difficult to preserve it in disarticulated bones. The relations
of the uncinate process are best studied by removing the outer wall of the antrum.
THE SPHENOIDAL TURBINAL
These bones (often referred to as the bones of Bertin) are two hollow cones,
flattened externally in three planes. They may be obtained as distinct ossicles
about the fifth year. At this date they are wedged in between the under surface
of the pre-sphenoid and the orbital and sphenoidal processes of the palate bone.
The apex of the cone is directed backwards, and appears near the vaginal process
of the sphenoid. Of its three surfaces, the outer one is in relation with the
spheno-maxillary fossa, and occasionally extends upwards between the sphenoid
FIG. 65.-THE SPHENOIDAL TURBINAL AT THE SIXTH YEAR.
and the os planum of the ethmoid to appear on the inner wall of the orbit (fig. 67).
The inferior surface forms the upper boundary of the spheno-palatine foramen,
and enters into the formation of the posterior part of the roof of the nasal fossa.
The superior surface lies flattened against the under surface of the pre-sphenoid.
The base of the cone is in contact with the posterior surface of the lateral mass of
the ethmoid.
At birth these bones are visible as small triangular ossifications in the peri-
chondrium of the ethmo-vomerine plate near its junction with the pre-sphenoid.
FIG. 66.-THE SPHENOIDAL TURBINALS FROM AN OLD SKULL.

SPHENOIDAL TURBINAL-
ROSTRUM OF SPHENOID.
By the third year they have become hollow cones, the circular orifice representing
the base eventually becoming the orifice of the sphenoidal sinus. As the cavity
enlarges, the median wall atrophies so that the inner wall of the sinus is formed
by the pre-sphenoid. As the turbinal enlarges it ankyloses with adjacent bones.
In many skulls it joins the lateral mass of the ethmoid; more frequently it fuses
with the pre-sphenoid; less frequently with the palate. After the twelfth year they
can rarely be separated from the skull without damage. In many disarticulated skulls

THE INFERIOR TURBINAL
57
they are so broken up that a portion is found on the sphenoid, fragments on the
palate bones, and the remainder attached to the ethmoid.
Sometimes, even in very old skulls, they are represented by a triangular plate
of extreme tenuity on each side of the rostrum of the sphenoid (fig. 66).
THE INFERIOR TURBINAL
These are a pair of delicate, scroll-like bones, and may be regarded as dis-
memberments of the lateral masses of the ethmoid, with which they are closely
related. Each bone presents two surfaces, two borders, and two extremities.
The outer surface is concave, and overhung by the auricular or maxillary
process. The inner surface is convex and pitted with depressions. The superior
border presents from before backwards three processes: the first is called the
lachrymal process, because it articulates with the turbinal process of the lachrymal
bone. The margin of bone at the base of this process comes into relation with
the nasal process of the maxilla. The second vertical spiculum is the ethmoidal
process, which joins the uncinate process of the ethmoid. The third or maxillary
process is a thin lamella of bone, turned downwards; it overhangs the orifice of
FIG. 67. THE INFERIOR TURBINAL, ADULT SPHENOIDAL, TURBINAL
AND LACHRYMAL BONES.
THE CREST OF LACHRYMAL
Tensor tarsi
THE ORBITAL SURFACE
LACHRYMAL GROOVE
HAMULAR PROCESS
TURBINAL PROCESS
THE LACHRYMAL PROCESS
THE ETHMOIDAL PROCESS
THE MAXILLARY PROCESS
OS PLANUM
THE SPHENOIDAL TURBINAL
WITH AN ORBITAL PROCESS
MIDDLE TURBINAL
the maxillary sinus, and serves to fix the bone firmly to the outer wall of the
nasal fossa. The margin posterior to the maxillary process comes into relation
with the inferior turbinal crest of the palate bone. The inferior border is rounded
and free. It is the thickest part of the bone. The extremities are narrow, the
posterior being the more pointed.
Articulations. The inferior turbinal articulates with the maxilla, lachrymal,
palate, and ethmoid.
The inferior turbinal is ossified from a single nucleus which appears about the
fifth month of intra-uterine life.
At birth it is a relatively large bone, and fills up the lower part of the nasal
fossa.
58
THE SKELETON
THE LACHRYMAL
The lachrymal bones are extremely thin and delicate, quadrilateral in shape,
and situated at the anterior part of the inner wall of the orbit. They are the
smallest of the facial bones.
The outer or orbital surface is divided by a vertical ridge into two unequal
portions. The anterior smaller portion is deeply grooved to form the lachrymal
sulcus, which lodges the lachrymal sac and forms the commencement of the
lachrymal duct. The portion behind the ridge is smooth, and forms part of the
inner wall of the orbit. The ridge gives origin to the tensor tarsi muscle, and
terminates inferiorly in a hook-like process, the hamulus, which curves forward to
articulate with the lachrymal tubercle of the maxilla and completes the superior
orifice of the lachrymal canal. The inner surface is in relation with the two
anterior cells of the ethmoid (lachrymo-ethmoid), and forms part of the infundi-
bulum. The superior border is short, and articulates with the internal angular
process of the frontal. The lower border posterior to the crest joins the inner edge
of the orbital plate of the maxilla. The narrow piece, anterior to the ridge,
is prolonged downwards to join the lachrymal spine of the inferior turbinal, and
is called the turbinal process. The anterior border comes into relation with
the posterior border of the nasal process of the maxilla. The posterior border
articulates with the os planum of the ethmoid.
Articulations. The lachrymal articulates with the ethmoid, maxilla, frontal and
inferior turbinal bones.
Blood-supply. Its arteries are derived from the infraorbital, the nasal branch
of the ophthalmic, and the anterior ethmoidal.
-
Ossification. This bone arises in the membrane overlying the cartilage of the
fronto-nasal plate. Its mode of ossification is very variable. As a rule it is
described as coming from one nucleus. Not infrequently the hamulus is a separate
element. Sometimes the bone is divided horizontally, and a process of the os
planum projects between the two halves to join the nasal process of the maxilla.
More rarely the bone is represented by a group of detached ossicles resembling
Wormian bones.

THE VOMER
The vomer is an irregular four-sided plate of bone constituting the lower portion
of the nasal septum. It is usually described as resembling a ploughshare in shape.
Each lateral surface is covered with the thick mucous membrane of the nasal sinus,
FIG. 68. THE VOMER. (Side view.)

ANTERIOR BORDER
GROOVE FOR NASO-PALATINE NERVE
GROOVE FOR SEPTAL CARTILAGE
INFERIOR BORDER
ALA
POSTERIOR BORDER
and is traversed by a narrow but well-marked groove, which lodges the naso-
palatine nerve from the spheno-palatine ganglion; hence it is sometimes called
the naso-palatine groove.
The superior border of the bone is expanded laterally into two ale. The groove

THE VOMER
59
between them lodges the rostrum of the sphenoid, whilst the margin of each ala
comes into contact with the sphenoidal process of the palate bone. Between the
alæ and the sphenoid a canal exists on each side of the rostrum for blood-vessels.
The inferior border is uneven, and is received into the groove formed by the crests
of the opposed maxillæ and the palatine bones of each side. The anterior border
joins posteriorly the mesethmoid, and in front the triangular (median) nasal cartilage.
The posterior border, smooth, rounded, and covered with mucous membrane, serves
to separate the posterior nares. The anterior and inferior borders meet each other
at the apex of the bone.
Articulations.-The vomer articulates with the sphenoid, palates, ethmoid, and
maxillæ, and with the triangular cartilage.
FIG. 69.-THE VOMER AT BIRTH.

Blood-supply. Its arteries are derived from the anterior and posterior ethmoidal,
the naso-palatine, and the pterygo-palatine arteries, and twigs from the posterior
palatines through Stenson's canals.
Ossification. The vomer is a membrane bone, and arises from a single centre
deposited in the lower border of the perichondrium of the ethmo-vomerine plate
as early as the eighth week. From this single centre a lamina of bone extends
on each side of the cartilage plate. For many weeks the vomer is a shallow
bony trough. Gradually it presses upon and induces absorption of the enclosed
cartilage, and by degrees the laminæ fuse, and form a rectangular plate of bone.
At birth the vomer presents an expanded lower border, especially in cases of cleft
palate.
THE NASAL
These are two oblong bones situated in the middle line at the upper part of the
face, and forming the bridge of the nose. Each bone has two surfaces and four
borders. The facial surface is concave from above downwards, but convex from
side to side. Near its centre is a foramen for the transmission of a small tributary
to the facial vein. The posterior or nasal surface is concave laterally, and traversed
by a longitudinal groove for the nasal branch of the ophthalmic nerve. In life
this surface has a covering of mucous membrane. The short superior border is
thick and serrated for articulation with the nasal notch of the frontal. The inferior
border is thin, and serves for the attachment of the lateral nasal cartilages. Each
bone articulates with its fellow by the median border, which is prolonged backwards
to form a crest; this crest comes into relation with the nasal spine of the frontal
and the anterior border of the mesethmoid. The outer border articulates with the
nasal process of the maxilla.

60
THE SKELETON
Articulations.--The nasal bone articulates with its fellow, the frontal, maxilla,
and ethmoid.
Blood-supply.-Twigs to this bone are furnished by the nasal branch of the
ophthalmic, the frontal, the angular, and the anterior ethmoidal arteries.
Ossification. Each nasal bone is developed from a single earthy nucleus in the
FIG. 70.-THE LEFT NASAL BONE.
SUPERIOR BORDER
MEDIAN BORDER
OUTER BORDER
INFERIOR BORDER
MEDIAN BORDER
GROOVE FOR NASAL NERVE
membrane overlying the fronto-nasal cartilage. The nucleus is easily seen in the
eighth week. The bone by its pressure soon produces absorption of the underlying
cartilage. At birth the nasal bones are nearly as wide as they are long, whereas
in the adult the length of the bones is three times greater than the width.
THE MAXILLA
The maxillæ are two hollow irregular cuboidal bones with two prominent
processes. They form a large portion of the facial skeleton.
This bone is occupied by a large cavity, the antrum. The body presents four
surfaces. Of these the facial surface looks forwards and outwards and presents
the following points of interest :-The socket for the canine tooth causes a low
elevation, the canine eminence, having to its inner side the incisive fossa, from
which the depressor ala nasi arises. On the outer side of the eminence is the
canine fossa, which gives origin to the levator anguli oris. Above this fossa is
the infraorbital foramen, through which the terminal branches of the infra-
orbital nerve and artery emerge. From the ridge above this foramen the levator
labii superioris arises.
A ridge of bone extending upwards from the socket of the second molar tooth
separates the facial from the zygomatic surface. Near the middle of the zygomatic
surface are the orifices of the canals for the posterior dental nerves and vessels.
The posterior inferior angle of this surface is termed the tuberosity; from it a
few fibres of the internal pterygoid muscle arise. This tuberosity is most prominent
after eruption of the wisdom tooth; the rough surface along its inner border is
for the tuberosity of the palate bone; the smooth surface immediately above
forms the anterior boundary of the spheno-maxillary fossa, and enters into the
formation of the descending palatine canal.
The orbital surface is irregularly triangular and forms the floor of the orbit.
Anteriorly it is rounded and forms part of the circumference of the orbit; externally
it is rough for suture with the malar bone; the rough surface ends in a backwardly
projecting spine which occasionally joins the sphenoid and forms the anterior
limit of the spheno-maxillary fissure. The posterior margin, smooth and rounded,
forms the inferior limit of the spheno-maxillary fissure. The internal border is
nearly straight; quite at the posterior part is a gap for the orbital process of the
palate bone; anteriorly it articulates with the os planum of the ethmoid; beyond
this it receives the lachrymal bone, and in the anterior angle it is smooth and

THE MAXILLA
61
rounded, forming part of the circumference of the orbital orifice of the lachrymal
duct.
The orbital surface is traversed by the infraorbital groove, which, commen-
cing at the posterior border, deepens as it passes forwards and enters the infra-
orbital canal. This groove receives the second division of the fifth nerve and the
infraorbital artery. The infraorbital canal runs under the margin of the orbit
FIG. 71. THE LEFT MAXILLA. (Outer view.)
INFRAORBITAL FORAMEN
NASAL NOTCH
NASAL
PROCESS
ORBITAL
SURFACE
CANINE FOSSA-
NASAL SPINE
INCISIVE FOSSA
FACIAL
SURFACE
CANINE EMINENCE
BORDER OF SPHENO-
MAXILLARY FISSURE
FOR SPHENOID
ZYGOMATIC SURFACE
MALAR PROCESS
POSTERIOR DENTAL CANALS
TUBEROSITY
and opens on the facial surface. It transmits the infraorbital artery and nerve.
At the termination of the groove a smaller canal tunnels the anterior wall of the
antrum, and conveys the anterior dental nerves and vessels to the upper incisor,
canine, and bicuspid teeth. External to the commencement of the lachrymal duct
there is a shallow depression from which the inferior oblique takes origin.
The internal or nasal surface forms the outer wall of the nasal fossa, and is
FIG. 72. THE LEFT MAXILLA. (Inner view.)
ANTRUM
POSTERIOR PALATINE GROOVE
PALATINE PROCESS
NASAL PROCESS
RIDGE FOR MIDDLE TURBINAL
LACHRYMAL GROOVE
RIDGE FOR INFERIOR TURBINAL
NASAL SPINE
CREST
ANTERIOR PALATINE GROOVE
prolonged inwards to form part of the floor of this fossa. The posterior half of this
surface is deficient, and leads by a large irregular aperture into the antrum; below
and behind this opening the bone is rough for articulation with the vertical plate
of the palate bone. The extreme posterior border receives the tuberosity of the
palate bone; the groove in front of it forms part of the posterior palatine canal.
Anterior to this surface the bone becomes suddenly smooth; between the smooth
62
THE SKELETON

and rough portions is the maxillary fissure for the reception of the thin maxillary
process on the anterior border of the vertical plate of the palate bone. In the
angle between this surface and the nasal process is a deep groove converted by the
lachrymal and inferior turbinal into the nasal duct. Running backwards from
the anterior margin is the inferior turbinated crest which articulates with the
lowest turbinal bone. The surface above the crest forms part of the middle
meatus, and the surface below belongs to the inferior meatus of the nose, and is
directly continuous with the superior surface of the palatine process. Near its
anterior border is the orifice of the anterior palatine canal.
The inferior or palatine surface is formed by the palatine process and the
alveolar border. The palatine process forms the anterior part of the roof of the
mouth. It is concave, rough, and pitted with foramina for vessels. Where it
joins the alveolar border a groove (sometimes a canal) exists for the anterior
palatine nerve and posterior palatine vessels. When the bones of opposite sides.
are placed in apposition the palatine fossa is formed; running outwards from this
to the space between the second incisor and canine tooth, the maxillo-premaxillary
suture can be detected in young bones. The posterior border articulates with the
horizontal process of the palate bone, whilst the median border joins its fellow to
form, above, a prominent crest upon which the vomer is received.
The anterior palatine fossa is situated in the meso-palatine suture near its
anterior termination. In its typical form the fossa contains four passages: two are
small and disposed one behind the other exactly in the suture; these are the
foramina of Scarpa for the naso-palatine nerves, the left nerve emerging from the
anterior foramen. The lateral and larger orifices diverge to open on each side of the
crest. They are called Stenson's canals, and lodge recesses of the nasal mucous
membrane and remnants of Jacobson's organs.
The alveolar ridge forms the outer limit of this surface; it is crescentic in
shape, spongy in texture, and presents cavities in which teeth are lodged. When
the teeth are complete in number, eight cavities are present; of these the pit for
the canine tooth is the deepest, those for the molars are the widest and present
subdivisions. Along the outer aspect of the alveolar border the buccinator arises
as far forward as the first molar tooth.
The nasal process is somewhat triangular, standing vertically from the nasal
angle of the maxilla. Its outer surface gives attachment to the orbicularis
palpebrarum, the tendo oculi, and the levator labii superioris alæque nasi. The
internal surface forms one of the lateral boundaries of the nasal fossa. Superiorly
it articulates with the frontal; below this is the superior turbinated crest for
articulation with the middle turbinal. The space between this and the inferior
turbinated crest forms part of the middle meatus. The anterior border articulates
with the nasal bone; the posterior is thick and vertically grooved to form part of
the nasal duct. The inner margin of this groove articulates with the lachrymal
bone. The point where the outer margin of the groove joins the orbital plate is
indicated by the lachrymal tubercle.
The malar process is rough and triangular, and forms the summit of the
ridge of bone separating the facial and zygomatic surfaces. It articulates with
the malar bone, and from its inferior angle a few fibres of the masseter take origin.
The antrum or maxillary sinus, as the air-chamber occupying the body of the
bone is called, is somewhat pyramidal in shape; the base being represented by the
nasal or internal surface, and the apex corresponding to the malar process. In
addition to these it has four walls: the superior is formed by the orbital plate, and
the inferior by the alveolar ridge. The anterior wall corresponds to the facial
surface of the maxilla, and the posterior is formed by the zygomatic surface. The
inner boundary or base presents a very irregular orifice at its posterior part; this
is partially filled in by the vertical plate of the palate bone, the uncinate process of





THE MAXILLA
63
the ethmoid, the maxillary process of the inferior turbinal, and a small portion of
the lachrymal bone. Even when these bones are in situ, the nasal orifice is very
irregular in shape, and requires the mucous membrane to form the definite rounded
aperture (or apertures, for they are often multiple) known as the opening of the
antrum. The cavity of the antrum varies considerably in size and shape. In the
young it is small and the walls are thick: as life advances, the antrum enlarges
at the expense of its walls, and in old age they are often of extreme tenuity;
occasionally the cavity extends into the substance of the malar bone. The floor of
the antrum is, as a rule, very uneven, due to prominences corresponding to the
roots of the molar teeth. In most cases the bone separating the teeth from the
antrum is very thin, and not rarely the roots project uncovered into it. The
teeth which come into closest relationship with the antrum are the first and second
molars, but the sockets of any of the teeth lodged in the maxilla may, under
diseased conditions, communicate with it. Although, as a rule, the cavity of the
antrum is single, yet specimens occasionally come to hand in which it is divided
by bony septa into chambers, and it is far from uncommon to find it divided into
recesses by bony processes. In many maxillæ, the roof of the antrum presents
near its anterior aspect what appears to be a thick rib of bone; this is hollow
and corresponds to the infraorbital canal.
The most satisfactory method of studying the relation of the bones closing in
the base of the antrum is to cut away the outer wall of the cavity (see fig. 84).
Articulations. The maxilla articulates with its fellow, and with the frontal,
nasal, lachrymal, ethmoid, palate, vomer, malar and inferior turbinal bones. Occa-
FIG. 73.-OSSIFICATION OF THE MAXILLA,
PRE-MAXILLARY PORTION
Outer view.
Inferior view.
Inner view.
sionally it articulates with the greater wing, and less frequently with the pterygoid
process of the sphenoid bone.
The muscles attached to it are mainly those known as muscles of expression
Compressor naris.
Orbicularis palpebrarum.
Levator labii superior proprius.
Orbicularis oris.
Levator labii superioris alæque nasi.
Masseter.
Levator anguli oris.
Inferior oblique.
Depressor alæ nasi.
Buccinator.
Internal pterygoid.
Blood-supply. The maxilla is a very vascular bone, and its arteries are nume-
rous and large. They are derived from the infraorbital, alveolar, descending palatine,
naso-palatine, ethmoidal, frontal, nasal, and facial branches.
Ossification. The maxilla arises from four centres which are deposited in
membrane.
The various centres may be termed pre-maxillary, maxillary, malar, and

64
THE SKELETON
pre-palatine. They arise about the eighth week of embryonic life, and fuse very
rapidly.
(a) The pre-maxillary nucleus gives rise to that portion of the bone which
lodges the incisor teeth. It sends a narrow process upwards which forms part of
the outer boundary of the anterior narial aperture. On the palatine aspect it
furnishes a spiculum which surrounds the anterior and mesial aspect of Stenson's
canal. The posterior limit is indicated up to the end of the first dentition by the
maxillo-premaxillary suture. The greater part of this centre is formed in
membrane, but the inner part subsequently invades the ethmo-vomerine cartilage.
(b) The maxillary nucleus forms the nasal process, and the greater part of the
body of the maxilla.
(c) The malar centre gives origin to that portion of the bone lying external to
the infraorbital groove.
(d) The pre-palatine centre gives rise to the nasal surface of the maxilla and
the palatine process posterior to Stenson's canal. This portion is in shape similar
to the palate bone.
THE PALATE BONE
The palate bone is rectangular in shape, and wedged between the maxilla and
the pterygoid processes of the sphenoid. It has a horizontal and a vertical plate,
a tuberosity, and two processes.
The horizontal plate is smaller than the vertical; it is quadrilateral in shape.
The upper surface forms the floor of the nasal fossa; the inferior surface completes
the hard palate posteriorly, and presents near its posterior border a transverse ridge,
which gives attachment to the tensor palati muscle. The anterior border is rough
for articulation with the palatine process of the maxilla. The posterior border is
free, curved, and sharp; it gives attachment to the soft palate. The inner border
is broad, and rough for articulation with its fellow. When the palate bones are in
apposition, these borders form a ridge continuing the crest formed by the palatine
processes of the maxilla; this crest receives the inferior border of the vomer.
posterior extremity of the crest forms the posterior nasal spine, from which the
azygos uvula arises.
The
The vertical plate is thin; of its two surfaces, the outer is rough for articula-
tion with the maxilla, except a small portion near the middle close to the anterior
border where it looks into the antrum, and a small triangular surface at the upper
end where it forms part of the spheno-maxillary fossa. Towards the posterior
border there is a vertical groove, which forms with the maxilla the posterior palatine
canal; it transmits the descending palatine nerves and vessels. The canal may be
more or less complete in the palate bone. The internal surface has two transverse
ridges separating three shallow depressions. Of these depressions the lower forms part
of the inferior meatus of the nose, and the limiting ridge or crest articulates with the
inferior turbinal. Above this is the depression for part of the middle meatus; the
ridge above is for the second turbinal. The upper groove is narrower and deeper than
the lower two, and forms a large part of the superior meatus. The ridges are known
as the turbinated crests. The borders of the vertical plate are terminated by
irregular prominences, which enter into complex union with surrounding bones.
The posterior border is vertical, and comes into relation with the anterior
border of the internal pterygoid process; below, it terminates in a prominent
tuberosity. This presents three grooves or flutes: the inner receives the internal
pterygoid, the outer the external pterygoid process, while the middle groove com-
pletes the pterygoid fossa, and affords attachment to a few fibres of the internal
pterygoid muscle; the superior constrictor of the pharynx also arises from this
process. The tuberosity is tunnelled by canals: to the nasal side are the accessory

THE PALATE BONE
65
palatine canals; near its junction with the horizontal plate is the orifice of the
posterior palatine canal; and outside this occasionally may be found the minute
external palatine canals (fig. 85).
The sphenoidal process, which is a process of variable shape, surmounts the
posterior border; it has three surfaces and two borders. The superior surface
comes into apposition with the sphenoidal turbinal bone, and forms part of the
FIG. 74.-PALATE (LEFT) BONE. (Inner view.)
LORBITAL PROCESS
(ETHMOIDAL SURFACE)
SPHENOIDAL PROCESS-
SPHENO-PALATINE NOTCH
(WHEN THE FORAMEN IS
COMPLETE IN THE PALATE
BONE, IT IS DUE TO ANKY-
LOSIS WITH SPHENOIDAL
TURBINAL)
-SUPERIOR MEATUS
-SUPERIOR TURBINATED CREST
MIDDLE MEATUS
INFERIOR TURBINATED CREST
INFERIOR MEATUS
pterygo-palatine canal. The internal surface forms part of the outer wall of the
nasal fossa, and is prolonged on to the roof, and comes in contact with the ala of
the vomer.
The outer surface is subdivided by a thin lip into an anterior smooth
portion for the spheno-maxillary fossa, and a posterior rough part for the base of
the internal pterygoid plate. Of the borders, the posterior is thin and articulates
with the internal pterygoid plate; the anterior border forms the posterior boundary
of the spheno-palatine foramen.
FIG. 75.-PALATE BONE. (Posterior view.)
ORBITAL SURFACE-
ZYGOMATIC SURFACE-
SPHENO-PALATINE FORAMEN-
(USUALLY A NOTCH)
ORBITAL PROCESS
(SURFACE FOR SPHENOIDAL
TURBINAL)
SPHENOIDAL PROCESS
GROOVE FOR EXTERNAL PTERYGOID.
GROOVE FOR PTERYGOID FOSSA
GROOVE FOR INTERNAL PTERYGOID-
TUBEROSITY
SPINE OF PALATE
The anterior border of the vertical plate is thin, sharp, and presents near the
middle the maxillary process, which is received into the maxillary fissure of the
maxilla near the lower border of the opening of the antrum.
Superiorly this border is terminated by the orbital process. This process presents
five surfaces; of these, three are articular. The posterior surface joins the walls of
the sphenoidal turbinal bone, its air-cells extending occasionally into this part of the
F
66
THE SKELETON

palate bone. In the same way the posterior ethmoidal cells extend into the inner
surface of the orbital process, where they articulate with the lateral mass. The
anterior surface is a continuation of the outer aspect of the vertical plate, and
rests upon the maxilla. Of the two non-articular surfaces, the one directed
upwards and outwards is slightly concave, and forms part of the floor of the
orbit at its junction with the inner wall. The outer smooth surface looks
directly into the zygomatic fossa, and extends into the spheno-maxillary fossa,
and forms the anterior boundary of the spheno-palatine foramen. These surfaces
are often conveniently named according to the bones with which they articu-
late, or the fossæ which they help to form: thus, the anterior or maxillary;
internal or ethmoidal; posterior or sphenoidal; superior or orbital; external or
zygomatic.
Between the orbital and sphenoidal processes is the spheno-palatine notch, which
is converted by the sphenoid turbinal bone into a complete foramen. Occasionally
it is complete in the palate bone. It transmits the spheno-palatine nerve and
artery; the foramen opens into the back part of the nasal fossa, close to its roof.
When the spheno-palatine foramen is complete in the palate bone, it is often due
to ankylosis between the palate and the sphenoidal turbinal; the latter, being
extremely fragile, easily breaks during the process of disarticulation.
Articulations. The palate bone articulates with its fellow the sphenoid,
maxilla, vomer, sphenoidal turbinal, inferior turbinal, and ethmoid bones. As
the surfaces and lines of union of the orbital and sphenoidal processes are
somewhat intricate, the student should, when studying this bone, refer to the
following figures. The orbital and zygomatic surfaces are shown in fig. 84. The
relation of the sphenoidal process to the nasal fossa in fig. 64. The relations of
the pterygoid processes to the tuberosity of the palate are shown in fig. 85. With
the help of these drawings the student will be able to understand the position of
this bone, which assists in forming the boundary of the following cavities: viz. the
nasal, orbital, spheno-maxillary, antral, and the ethmoidal cells.
The muscles attached to it are:-
Internal pterygoid.
Tensor palati.
Superior constrictor of pharynx.
Azygos uvulæ.
Blood-supply.--Its arteries are derived from the descending palatine, the
spheno-palatine, and pterygo-palatine.
Ossification. The palate bone arises from one nucleus, which is deposited in
membrane, and appears about the eighth week of embryonic life. The spot where
the earthy matter is first seen ultimately becomes the angle where the vertical and
horizontal plates join. At birth the two plates are nearly equal, but as the nasal
sinuses increase in height the vertical plate is lengthened, until it becomes twice
the length of the horizontal plate.
THE MALAR

The malar bone, somewhat quadrilateral in shape, is situated at the outer and
upper side of the face, and forms the prominence known as the cheek.
Each bone has a convex external surface, presenting near the centre one or
two minute orifices for the transmission of the malar nerves and arteries. This
surface is largely covered by the orbicularis palpebrarum, and gives origin to the
zygomatici major and minor.
The internal surface is concave, and abruptly excluded from the orbit by a
prominent ledge of bone, the orbital process, which forms the anterior boundary of


THE MALAR BONES
67
the temporal fossa. A large part of this surface is rough for articulation with the
malar process of the maxilla. The orbital process of the malar is at right angles
with the external surface, and presents the orbital orifice of the malar canal; this
canal is usually single, but it may bifurcate as it traverses the bone, one branch
emerging on the external, the other on the internal surface. The thin edge of this
process articulates inferiorly with the orbital plate of the maxilla, and ends in a
point known as the maxillary process. The superior portion articulates with the
malar crest on the external surface of the greater wing of the sphenoid; in the
suture between these bones a notch (sometimes a foramen) exists for the temporal
branch of the fifth nerve. When the orbital surface is large, it excludes the
sphenoidal wing from articulation with the maxilla at the anterior extremity of the
spheno-maxillary fissure. When this is the case, the border presents near its
middle a short non-serrated margin.
The malar bone presents superiorly the frontal process, which articulates with
the external angular process of the frontal bone. The maxillary process articulates

FIG. 76. THE LEFT MALAR BONE.

FRONTAL PROCESS
ORBITAL BORDER
POSTERIOR BORDER
MALAR CANAL-
MAXILLARY PROCESS
ANTERIOR BORDER-
ZYGOMATIC PROCESS
INFERIOR BORDER
NOTCH FOR TEMPORAL-
NERVE
FOR SPHENOID-
ORBITAL PROCESS
MALAR CANAL
MALAR CANAL
MAXILLARY PROCESSled
MAXILLARY SURFACE
with the maxilla, and occasionally forms the superior segment of the infraorbital
foramen. The zygomatic process is directed backwards, and is serrated mainly on
its inner aspect for articulation with the zygoma.
Of the four borders, the orbital is the longest, and extends from the frontal to
the maxillary process. It is thick, rounded, and forms the outer and a large portion
of the inferior circumference of the orbit. The inferior is continuous with the
zygoma, and gives origin to the anterior fibres of the masseter. The anterior border
is in relation with the maxilla, and near the margin of the orbit gives origin to a
portion of the levator labii superioris proprius. The posterior border extends from
the frontal to the zygomatic process, and presents a double curve; it gives attach-
ment to the temporal fascia. This border is directly continuous below with the
upper border of the zygoma, and above with the temporal ridge.
Articulations. The malar articulates with the maxilla, frontal, sphenoid, and
temporal bones.
Blood-supply. The arteries of the malar are derived from the infraorbital,
F 2

68
THE SKELETON
lachrymal branches of the ophthalmic, transverse facial, and deep temporal
arteries.
The muscles connected with it are:-
Zygomaticus major.
Masseter.
Zygomaticus minor.
Ossification. The malar is a membrane-bone, and arises from two and occa-
sionally three centres, which appear in the eighth week of embryonic life, and
grow with astonishing rapidity: the bone quickly attains a relatively large size.
Occasionally the two primary nuclei fail to coalesce, and the bone is represented
in the adult by two portions separated by a horizontal suture. Such bipartite
malars have been observed in skulls obtained from at least a dozen different races
of men. Bipartite malars have been seen with the suture vertical. That the bone
may arise from three centres is shown by the fact that tripartite malars have
been observed.
At birth the maxillary process reaches as far forwards as the outer border of
the infraorbital canal; subsequently it may send a process over the canal.
THE APPENDICULAR ELEMENTS OF THE SKULL
The bones which form this group are the mandible (lower jaw), malleus, incus,
stapes, hyoid, the styloid process of the temporal bone, and the internal pterygoid
process of the sphenoid.
THE MANDIBLE OR LOWER JAW
The mandible (lower jaw or inferior maxilla) is in shape like a horseshoe; it
consists of a horizontal portion or body, and two vertical portions or rami.
The body consists of a right and a left half, meeting in the middle line to form
the symphysis. Each half presents two surfaces and two borders. The external
surface is smooth and generally convex, and presents the following points of
interest :-The symphysis ends inferiorly in a triangular surface which forms the
chin. Near the symphysis is the incisive fossa, from which the levator menti
arises; external to this is the mental foramen through which the mental nerve
and artery issue. This foramen is in a line with the second bicuspid tooth.
Extending backwards and upwards from the mental protuberance, so as to
become continuous with the anterior border of the coronoid process, is the external
oblique line; along its upper border the depressor labii inferioris and depressor
anguli oris arise; the platysma is attached to its lower edge. The internal
surface presents, at a point corresponding to the symphysis, two pairs of genial
tubercles. The upper pair give origin to the genio-hyo-glossi, and the lower pair
afford insertion to the genio-hyoid muscles. The tubercles occasionally form a
single, median, irregularly shaped eminence. By the side of the genial tubercles
there is a shallow smooth depression, the sublingual fossa; below this is the
digastric fossa for the insertion of the anterior belly of the digastric muscle.
Posterior to the genial tubercles, the internal oblique line (mylo-hyoid ridge)
commences and extends backwards, becoming more and more prominent as it
approaches the alveolar border. The mylo-hyoid muscle is inserted along the whole

THE MANDIBLE
69
length of this ridge. At the posterior part the superior constrictor takes origin,
and the pterygo-maxillary ligament is attached to its posterior extremity. Below
the internal oblique line is the submaxillary fossa, which is in relation with the
submaxillary gland.
The inferior border of the body of the mandible is smooth and rounded; near
its junction with the ramus there is a groove for the facial artery. The superior
border is composed of spongy bone, and is named the alveolus; it presents sockets
for eight teeth. From the outer edge of the alveolus, as far forward as the first
molar tooth, the buccinator muscle takes origin.
The ramus is quadrilateral in shape. It has two surfaces, four borders, and
two processes. The external surface is for the insertion of the masseter muscle.
The internal surface presents near its middle the mandibular (inferior dental)
foramen which leads into the mandibular (inferior dental) canal which traverses
FIG. 77. THE MANDIBLE. (Outer view.)
Temporal CORONOID PROCESS SIGMOID NOTCH External pterygoid
MENTAL
FORAMEN
Levator
menti
Depressor
labii inf.
THE CHIN OR
MENTAL PRO-
TUBERANCE
RAMUS..
Buccinator
BODY.
Masseter.
CONDYLE
NECK
-Capsular
and
External
lateral
ligament
ANGLE
Platysma
BAL GROOVE FOR FACIAL ARTERY
Depressor anguli oris
EXTERNAL OBLIQUE LINE
the body of the bone and emerges at the mental foramen. This canal presents a
series of fine apertures above, through which filaments of the mandibular nerve
and artery pass to the teeth. In its posterior two-thirds the canal is nearer the
internal, in its outer third it is nearer the external surface of the mandible. The
posterior orifice of the canal is surmounted by the mandibular spine to which the
spheno-mandibular ligament is attached. Running obliquely downwards behind
this spine is the mylo-hyoid groove, which lodges the mylo-hyoid nerve and artery.
In the embryo, Meckel's cartilage also occupies the groove. The triangular rough
space behind this groove is for the insertion of the internal pterygoid muscle.
The inferior border of the ramus is thick, rounded, and continuous with the lower
border of the body of the bone. The posterior border is rounded; to its lower part
the stylo-maxillary ligament is attached. This border is surmounted by the condyle,
which is connected with the ramus by a somewhat constricted portion, the neck.
The condyle is oval in shape, with its long axis transverse to the upper border

70
THE SKELETON
of the ramus, but oblique with regard to the median axis of the skull, so that the
outer is more anterior than the inner angle, and presents the condyloid tubercle
for the external lateral ligament of the temporo-mandibular articulation. The
convex surface of the condyle is covered with cartilage and rests in the glenoid
fossa; the neck is flattened in front and presents a pit, for the insertion of a
portion of the external pterygoid muscle. The superior border of the ramus is
known as the sigmoid notch; it is terminated anteriorly by the coronoid. process.
This is a pointed process with two borders and two surfaces; the inner surface
presents a ridge, commencing at the tip, and becoming continuous with the inner
edge of the alveolus. To this ridge, to the area of bone in front of it and the tip
of the coronoid process, the temporal muscle is inserted; its outer surface affords
attachment to the masseter and a few fibres of the temporal. The anterior border
of the ramus is continuous with the external oblique line on the body of the bone.
Blood-supply.-The mandible is very vascular, and receives a large supply from
FIG. 78. THE MANDIBLE. (Inner view.)
External.
pterygoid
Capsule-
MANDIBULAR
SPINE
MANDIBULAR
FORAMEN
Spheno-
mandibular
ligament
Superior
constrictor
Mylo-hyoid
groove
Internal
pterygoid
Stylo-
mandibular
ligament
Temporal
Buccinator
Mylo-hyoid
INTERNAL OBLIQUE LINE
GROOVE FOR SUBMAXILLARY GLAND
GROOVE FOR
SUBLINGUAL
GLAND
Genio-hyo-
glossus
Genio-
hyoid
Digastric
the mandibular branch of the internal maxillary artery. This constitutes its main
supply. It receives twigs also from the facial artery.
It gives attachment to the following muscles :-
Buccinator.
Depressor labii inferioris.
Internal pterygoid.
External pterygoid.
Depressor anguli inferioris.
Platysma myoides.
Levator menti.
Genio-hyoid.
Genio-hyo-glossus.
Mylo-hyoid.
Superior constrictor of pharynx.
Digastric.
Temporal.
Orbicularis oris.
Masseter.
Ossification.
The mandible has six points of ossification for each lateral half.
All these, with the exception of one, are deposited in membrane. The nuclei are
deposited very early (between the sixth and eighth week), and fuse so rapidly that
observations on the development of this bone are unusually difficult.

THE MANDIBLE
71
Its six centres are mainly named according to their position.
The mento-Meckelian.-This is deposited in the distal end of Meckel's (mandi-
bular) cartilage, and gives rise to that portion of the bone between the symphysis
and the mental foramen.
FIG. 79.-THE MANDIBLE AT BIRTH.
OUTER VIEW
INNER VIEW
The dentary. This forms the lower border and outer plate, and supports the
teeth, hence its name.
The coronoid. This gives rise to the process of that name.

FIG. 80. THE SKULL OF AN OLD WOMAN EIGHTY-THREE YEARS OLD, TO SHOW
THE CHANGES IN THE MANDIBLE, AND MAXILLA.
www
The condyloid. This forms the condyle and adjacent portion of the neck of
the bone.
The angular. This gives rise to the angle of the bone.
The splenial. This centre appears three weeks later than the portions already

72
THE SKELETON
mentioned. It forms the inner plate of the mandible from near the symphysis to
the mandibular foramen. The mandibular spine represents the posterior extremity
of the splenial. Its line of junction with the dentary is indicated in the adult bone
by the mylo-hyoid groove.
At birth the mandible is represented by two nearly horizontal troughs of bone
lodging unerupted teeth. Each half is joined at the symphysis by fibrous tissue.
The upper edge of the symphysis and the condyles are nearly on a level. The
mandibular nerve lies in a shallow groove between the dentary and splenial
plates.
During the first year the two halves ankylose, union taking place from below
upwards, but the ankylosis is not complete until the second year. After the first
dentition, the ramus forms with the body of the mandible an angle of about 140°,
and the mental foramen is situated midway between the upper and lower borders
of the bone opposite the second milk-molar. In the adult, the angle formed by the
ramus and body is nearly a right angle, and the mental foramen is opposite the
second bicuspid, so that its relative position remains unaltered after the first
dentition. In old age, after the fall of the teeth, the alveolar margin is absorbed,
the angle formed by the ramus and body becomes obtuse, and the mental foramen
approaches to the alveolar margin. In a young and vigorous adult the mandible
is, with the exception of the petrosal, the densest bone in the skeleton, and resists
decay longest; in old age it becomes exceedingly porous, and often so soft that it
may be broken easily.
THE HYOID, THE STYLOID PROCESS, AND THE EAR BONES
The hyoid or lingual bone consists of a body and four processes. The body
(basi-hyal) forms the central portion of the bone; it is somewhat oblong in shape.
Its anterior aspect is convex and divided by a longitudinal ridge into a superior
and an inferior portion. Frequently it presents a median vertical ridge, and at
the point where the horizontal and vertical ridges intersect, a tubercle, sometimes
measuring four millimetres in length, is formed. The whole of the anterior surface
GREATER CORNU
LESSER CORNU
FIG. 81. THE HYOID.
BODY
is crowded with the origin and insertions of muscles. The posterior surface is
deeply concave, and frequently presents several small depressions near the middle
line which lodge accessory thyroid bodies.
The inferior border is free, the superior gives attachment to the thyro-hyoid
membrane. Between this membrane and the concavity of the hyoid a large bursa
is occasionally found. The lateral borders are in relation with the greater cornua,
but remain separated from them until late in life.

HYOID BONE AND STYLOID PROCESS
73
The greater cornua (thyro-hyals) project backwards and upwards. Their upper
and lower borders and anterior surfaces are occupied with muscles. Each corner
terminates posteriorly in a rounded tubercle, to which the thyro-hyoid ligament
is attached.
The lesser cornua (cerato-hyals) are small conical pieces of bone occupying the
upper part of the suture between the body and the greater cornua. Their tips are
continuous with the stylo-hyoid ligaments.
Muscles attached to the hyoid bone :--
Lingualis.
Genio-hyo-glossus.
Middle constrictor.
Sterno-hyoid.
Ligaments:-
Thyro-hyoid.
Digastric.
Genio-hyoid.
Thyro-hyoid.
Omo-hyoid.
Mylo-hyoid.
Hyo-glossus.
Hyo-epiglottideus
(when present).
Stylo-hyoid; and the thyro-hyoid membrane.
Blood-supply. The hyoid receives twigs from the arteries supplying the muscles
attached to it, in addition to direct supply from the superior thyroid and lingual
arteries.
Ossification.--At the third month the hyoid consists of hyaline cartilage; it is
directly continuous with the styloid process.
In the fourth month a nucleus
appears on each side of the middle line; they become quickly confluent to form the
body of the bone. In the fifth month each greater cornu has a conspicuous nucleus.
The centres for the lesser cornua are delayed until the second year.
The greater cornua remain separate from the body until after middle life. The
lesser cornua rarely ankylose with the body of the bone. As a rule, they are small
and inconspicuous; occasionally they are very long, and are sometimes continuous
with the styloid process of their respective sides.
The styloid process is a thin cylindrical spike of bone wedged in between the
tympanic plate and the petrosal immediately anterior to the stylo-mastoid foramen.
It consists of two parts: a tympano-hyal segment which in the adult is hidden
behind the tympanic plate, and a free projecting portion of variable length. As a
rule it varies from five to fifty millimetres. When short it is hidden by the vaginal
process, but it may reach to the hyoid bone. Its base forms the anterior boundary of
the stylo-mastoid foramen. The free portion gives origin to the following muscles:
The stylo-pharyngeus arises from the base posteriorly; the stylo-hyoid from the
outer aspect near the middle; and the stylo-glossus from the front near the tip.
The extremity of the process is continuous with the stylo-hyoid ligament. A band
of fibrous tissue the stylo-mandibular ligament-passes from the process below
the origin of the stylo-glossus to the angle of the mandible.
Muscles attached to the styloid process :-

Stylo-glossus.
Stylo-hyoid.
Stylo-pharyngeus.
Ligaments:-
Stylo-hyoid.
Stylo-mandibular.
The morphology and development of this process are described on page 98.
The malleus. This is the most external of the auditory ossicles, and comes
in relation with the tympanic membrane. Its upper portion, or head, is lodged in
the attic of the tympanum. It is of rounded shape, and presents posteriorly an
elliptical depression for articulation with the incus. Below the head is a constricted
portion or neck. From beneath the neck three processes diverge. The largest is
the handle or manubrium, which is slightly twisted and flattened. It forms an
obtuse angle with the head of the bone, and lies between the membrana tympani
and the mucous membrane covering its inner surface.

74
THE SKELETON
The tensor tympani tendon is inserted into the manubrium near its junction
with the neck on the inner side. The slender process (gracilis or Folian) is a long,
slender, delicate spiculum of bone (rarely seen of full length except in the foetus),
projecting nearly at right angles to the anterior aspect of the neck, and extending
obliquely downwards. It lies in the Glaserian fissure, and in the adult usually
becomes converted into connective tissue, except a small basal stump. The short
process is a conical projection from the outer aspect of the base of the manubrium.
Its apex is connected to the upper part of the tympanic membrane, and its base
FIG. 82. THE EAR BONES. (Modified from Henle.)
FOSSA FOR INCUS
SHORT PROCESS
ANTERIOR CRUS
STAPES
INCUS
LEFT MALLEUS
MALLEUS
HEAD OF MALLEUS
SHORT PROCESS
SLENDER PROCESS
HANDLE OR MANUBRIUM
LEFT INCUS
ARTICULAR SURFACE FOR MALLEUS
LONG PROCESS
ORBICULAR TUBERCLE
BASE
POSTERIOR CRUS
D
LEFT STAPES
NECK
BASE OF STAPES
receives the external ligament of the malleus. The malleus also gives attachment
to the suspensory ligament, and to the long anterior ligament of the malleus which
was formerly described as the laxator tympani muscle.
The incus.-This bone is situated between the malleus externally, and the
stapes internally. It presents for examination a body and two processes. The
body is deeply excavated anteriorly for the reception of the head of the malleus.

THE EAR BONES
75
The short process projects backwards, and is connected by means of ligamentous
fibres to the posterior wall of the tympanum, near the entrance to the mastoid
antrum. The long process is slender, and directed downwards and inwards; it
lies parallel with the handle of the malleus. On the inner aspect of the distal
extremity of this process is the orbicular tubercle, connected with the process
by a narrow neck. Its free surface articulates with the head of the stapes. The
orbicular tubercle is separate in early life.
The stapes is the innermost ossicle. It has a head directed horizontally out-
wards, capped at its outer extremity by a disc resembling the head of the radius.
The cup-shaped depression receives the orbicular tubercle of the incus. The base
occupies the the fenestra ovalis, and like this opening the inferior border is
straight, and the superior curved. The base is connected with the head by means
of two crura, and a narrow piece of bone called the neck. Of the two crura, the
anterior is the shorter and straighter. The crura with the base form a stirrup-
shaped arch, of which the inner margin presents a groove for the reception of the
membrane which is stretched across the hollow of the stapes.
In the early
embryo this hollow is traversed by the stapedial artery. The neck is very short,
and receives on its posterior border the tendon of the stapedius muscle.
THE EXTERIOR OF THE SKULL
The skull, when viewed from above, presents an oval outline; the posterior part
is broader than the anterior. The bones seen in this view are the frontal, parietals,
and the interparietal portion of the occipital. In a skull of average width the
zygomata come into view, but in very broad skulls they are obscured.
The sutures of the vertex are:-
The metopic, which is, in most skulls, merely a median fissure in the frontal
bone just above the glabella; occasionally it involves the whole length of the bone.
It is due to the persistence of the fissure normally separating the two halves of the
bone in the infant.
The sagittal is situated between the two parietals, and extends from the bregma
to the lambda.
The coronal lies between the frontal and parietals, and extends from pterion to
pterion.
The lambdoid is formed by the parietals and interparietal portion of the
occipital. It extends from asterion to asterion.
The occipital suture is only present when the interparietal exists as a separate
element (fig. 35).
The more important regions are:-
The bregma, which indicates the situation of the anterior fontanelle, and marks
the confluence of the coronal, sagittal and, when present, the metopic sutures.
The lambda, where the sagittal enters the lambdoid suture; it marks the
situation of the posterior fontanelle.
The obelion, a little anterior to the lambda, is usually indicated by a median
or two lateral foramina. It indicates the spot where the sagittal suture first
suffers obliteration.
Viewed from behind, the skull appears irregularly globular; the inferior part of
its circumference being somewhat flattened. The limits of the flattened portion
are indicated by the mastoid processes.
The centre is occupied by the occipital protuberance; this, with the occipital
crest and the three pairs of nuchal lines, give to the lower half a rough and uneven
appearance. The sutures in this view are the terminations of the sagittal,
lambdoidal and, when present, the occipital suture.

76
THE SKELETON
The occipital point (fig. 94) is the most posterior part of the skull, and is
exactly opposite the ophryon.
The inion corresponds to the external occipital protuberance.
The lateral aspect of the skull is very uneven; it presents three recesses or
fossæ. Its irregularity is increased by the zygoma.
The temporal fossa, semilunar in shape, is limited above by the superior
temporal ridge, and below by the zygoma.
The temporal ridge begins at the external angular process of the frontal bone,
and curves upwards and backwards to cross the frontal and parietal bones; it then
FIG. 83. THE SKULL. (Norma lateralis.)
STEPHANION
Flqju»ngv༼RS»
PTERION
Temporal
Masseter
Temporal
Bucemator
Buccinator
External pterygoid
Masseter
TEMPORAL
RIDGES
ASTERION
descends along the mastoid portion of the temporal bone to become continuous
with the upper border of the zygoma. In many skulls this ridge is double. The
lower ridge gives origin to the temporal muscle. The upper is the least constant ;
it diverges from the lower ridge as it approaches the coronal suture. At the
middle of the parietal bone the two ridges are often ten millimetres apart. This
ridge gives attachment to the temporal fascia. The fossa is almost entirely
occupied by the temporal muscle.
The zygomatic fossa is limited anteriorly by the zygomatic surface of the
maxilla; internally by the external pterygoid plate; externally by the zygomatic
arch and the ramus of the mandible; and posteriorly by a line drawn from the
foramen spinosum to the zygomatic tubercle. The outer surface of the greater

THE SPHENO-MAXILLARY FOSSA
77
wing of the sphenoid behind the pterygoid ridge and a small piece of the squamosal
form part of the upper boundary of the fossa.
The chief objects of interest in this region are:-The spheno-maxillary and
pterygo-maxillary fissures, the pterygoid ridge on the sphenoidal wing, the fora-
men ovale, foramen spinosum, and the articular eminence of the squamosal.
The spheno-maxillary fissure is horizontal in position, and lies between the
orbital border of the maxilla and the greater wing of the sphenoid; externally it
is completed usually by the malar; frequently the sphenoid will join the maxilla
and exclude the malar bone from the fissure; internally it is terminated by the
zygomatic surface of the orbital process of the palate bone. Through this fissure
the orbital, spheno-maxillary, and zygomatic fossæ communicate. The zygomatic
fossa lodges the temporal, external pterygoid, and internal pterygoid muscles.
The pterygo-maxillary fissure forms a right angle with the preceding. It is
situated between the maxilla and the anterior border of the external pterygoid
process. At its lower angle the external pterygoid plate occasionally articulates
FIG. 84.-A SECTION OF THE SKULL, SHOWING THE INNER WALL OF THE ORBIT, THE
BASE OF THE ANTRUM, AND THE SPHENO-MAXILLARY FOSSA.
FRONTAL SINUS-
NASAL BONE-
NASAL PROCESS OF MAXILLA.
LACHRYMAL-
LACHRYMAL CANAL-
ORIFICE OF ANTRUM.
INFERIOR TURBINAL.
PALATE BONE
ANTERIOR NASAL SPINE-
ANTERIOR ETHMOID CANAL
POSTERIOR ETHMOID CANAL
-OPTIC FORAMEN
-OS PLANUM OF ETHMOID
SPHENO-PALATINE FORAMEN
VIDIAN CANAL, LEADING INTO
THE SPHENO-MAXILLARY FOSSA
SPHENOID
EXTERNAL PTERYGOID PLATE
PALATE BONE
with the maxilla. The pterygo-maxillary fissure leads from the zygomatic fossa
directly into the spheno-maxillary fossa, a small space shaped like an inverted
pyramid, situated between the maxilla and the roots of the pterygoid processes. The
roof of this fossa is formed by the under surface of the greater wing of the sphenoid.
The anterior boundaries are a small portion of the zygomatic surface of the maxilla
and the orbital process of the palate; posteriorly it has the roots of the pterygoid pro-
cesses, and the lower part of the orbital surface of the greater wing of the sphenoid;
and internally the vertical plate of the palate bone. The apex of the pyramid leads
into the posterior palatine canal. The inner wall presents the spheno-palatine
foramen which leads into the nasal fossa. The posterior wall has three openings
in the following order, from without inwards, and from above downwards: the
foramen rotundum, Vidian canal, and pterygo-palatine canal. Anteriorly it com-
municates with the orbit by the spheno-maxillary fissure; and externally the
pterygo-maxillary fissure leads into the zygomatic fossa.
This fossa is mainly of interest on account of its relation to the spheno-palatine
(Meckel's) ganglion. The various foramina and canals connected with the fossa
78
3.2202 THE SKELETON

serve for the transmission of the nerves connected with this ganglion and the
terminal branches of the internal maxillary artery.
In addition to the fossæ, the lateral region presents the glenoid fossa with
its articular eminence, the external auditory meatus, the mastoid and styloid
processes, and the following sutures:-
The spheno-parietal, which lies between the greater wing of the sphenoid and
the anterior inferior angle of the parietal.
The squamous is formed by the squamosal overlapping the lower border of the
parietal.
The parieto-mastoid, which lies between the posterior inferior angle of the
parietal and the mastoid portion of the petrosal.
The zygomatic suture is formed by the union of the zygoma with the malar
bone.
The squamo-sphenoidal is situated between the anterior border of the squamosal
and the greater wing of the sphenoid.
The spheno-malar suture is formed by the orbital process of the malar and the
malar ridge on the greater wing of the sphenoid. Near its middle the suture is
perforated by the spheno-malar foramen, which allows the temporal branch of the
FIG. 85.-HARD PALATE OF A CHILD FIVE YEARS OLD.

PALATE BONE
GUBERNACULAR CANALS
ANTERIOR PALATINE FOSSA
MAXILLO-PREMAXILLARY SUTURE
PALATE PROCESS OF MAXILLA
POSTERIOR PALATINE FORAMEN
ACCESSORY PALATINE CANALS
orbital nerve and a branch of the lachrymal artery to escape from the orbit. This
foramen in some adult skulls is complete in the malar.
The fronto-squamosal is an occasional suture; when it is present, the anterior
inferior angle of the parietal is excluded from the greater wing of the sphenoid.
The more important regions are:-
The pterion, which marks the situation of the anterior lateral fontanelle, is
the meeting-place of the coronal, squamous, spheno-parietal, squamo-sphenoidal,
and the fronto-squamosal sutures. Frequently it is occupied in the adult by the
epipteric ossicle.
The asterion indicates the situation of the posterior lateral fontanelle and
marks the confluence of the squamosal, parieto-mastoid, lambdoid, the occipito-
mastoid, and occasionally the occipital sutures. Sometimes it is occupied by a
Wormian bone.
The stephanion is the spot where the superior temporal ridge cuts the coronal
suture.
The auricular point is the centre of the external auditory meatus.
The base of the skull is very irregular, and extends from the incisor teeth to the
occipital protuberance. Laterally it is limited by the zygomatic arches. Anteriorly

THE BASE OF THE SKULL
79
it presents the hard palate. When the skull is inverted the hard palate stands at
a higher level than the rest; it is bounded anteriorly and laterally by the alveolar
ridges containing the teeth. The bones appearing in the intermediate space are
the pre-maxillary and palatine portions of the maxillæ, and the horizontal
plates of the palate bones. The bone is rough for the attachment of the muco-
periosteum. The following points are readily recognised (fig. 85.):-
The meso-palatine suture commences at the alveolar point, traverses the
anterior palatine fossa, and terminates at the posterior nasal spine.
The transverse palatine suture between the palate bones and palatine processes
of the maxillæ.
In young skulls the maxillo-premaxiliary sutures, and behind the incisor teeth
four small openings known as the gubernacular canals.
The anterior palatine fossa containing the termination of four canals: two
small orifices, foramina of Scarpa, situated one behind the other in the meso-
palatine suture; and two larger openings, the foramina of Stenson. Scarpa's
foramina transmit the naso-palatine nerves; Stenson's are in relation with Jacob-
son's organs.
At the posterior angles of the hard palate are the posterior palatine foramina,
through which the posterior palatine vessels and the anterior palatine nerves
emerge on to the palate; a thin lip of bone separates them from the accessory
palatine foramina for the posterior palatine nerves. The accessory foramina are
in the tuberosity of the palate bone.
The hamular process of the internal pterygoid plate is the most posterior limit
of the hard palate.
At the posterior extremity of each alveolar ridge is the tuberosity of the maxilla.
Between the tuberosities of the maxilla and the palate bone are a few minute
foramina (variable in number and not always present), the external palatine canals
for the external palatine nerves.
Behind the hard palate are the posterior nares, separated from each other by the
vomer. Each is bounded externally by the internal pterygoid plate; below by the
horizontal plate of the palate bone; above by the under surface of the body of
the sphenoid, with the ala of the vomer and a portion of the sphenoidal process of
the palate bone.
External to the nares there is on each side a vertical fossa lying between the
pterygoid plates. It extends upwards to the under surface of the greater wings of
the sphenoid; it is completed anteriorly by the coalescence of the pterygoid plates,
and below by the tuberosity of the palate bone. It contains the following points
of interest:-
An elongated furrow, the scaphoid fossa, for the tensor palati muscle.
The general cavity of the pterygoid fossa which lodges the tensor palati and
internal pterygoid muscles.
Frequently there is a notch in the external pterygoid plate close beside the
foramen ovale.
The posterior termination of the Vidian canal.
If a line be drawn across the skull base from one zygomatic tubercle to the
other, it will fall immediately behind the external pterygoid plate and bisect the
foramen spinosum on each side. A second transverse line, drawn across the
opisthion or posterior margin of the foramen magnum, will fall behind the mastoid
processes. The space between these imaginary lines may be called the sub-cranial
region; that behind the second line the sub-occipital region. In addition to these
there is a lateral space anterior to the first line known as the zygomatic region.
Each will require separate consideration.
The sub-cranial region is formed by the following bones:-In the centre, the
under surface of the bodies of the sphenoid and occipital bones. Laterally, the


80
THE SKELETON
FIG. 86. THE SKULL. (Norma basilaris.)
Masseter
Digastric
Tensor palati
Azygos uvulæ
Superior constrictor
Internal pterygoid
Tensor palati
Tensor tympani
Levator palati
Rectus
Capitis
Lateralis
-Rectus capitis anticus major
-Rectus capitis anticus minor
-Anterior common ligament of spine
-Vertical part of crucial ligament
Check ligament
Capsular ligament
. Posterior occipito-atlantal ligament
Superior oblique
Rectus capitis posticus major
Rectus capitis posticus minor
Complexus
Ligamentum nucha
Trapezius

EXTERIOR OF THE SKULL
81
FIG. 87. THE SKULL. (Norma basilaris.)
SCARPA'S FORAMEN
STENSON'S FORAMEN
SCARPA'S FORAMEN
ANTERIOR PALATINE FOSSA
PALATINE GROOVE
POSTERIOR PALATINE FORAMEN
SPINE OF THE PALATE BONE
HAMULAR PROCESS
SPHENOIDAL PROCESS OF PALATE BONE
SPHENOTIC (MIDDLE LACERATED) FORAMEN
PHARYNGEAL TUBERCLE
CAROTID CANAL
ANTERIOR CONDYLOID FORAMEN
BASION
TUBERCLE FOR CHECK LIGAMENT
POSTERIOR CONDYLOID FORAMEN
OPISTHION
EXTERNAL OCCIPITAL CREST-
EXTERNAL OCCIPITAL PROTUBERANCE
G

82
THE SKELETON
petrosal, a small piece of the greater wing of the sphenoid, and of the squamosal,
and part of the occipital. It presents the following points in the middle line for
study:-
The pharyngeal tubercle.
The foramen magnum and the occipital condyles. The most anterior point of
the foramen is termed the basion, and the most posterior point the opisthion.
FIG. 88. THE SKULL. (Norma facialis.)
SURFACE COVERED BY
occipito-frontalis
Corrugator
supercilii
Tendo oculi
Orbicularis
palpebrarum
Levator labii supe-
rioris alæque nasi
Zygomaticus
major
Zygomaticus
minor
Levator labii
superioris
Levator anguli oris
Compressor naris
Depressor alæ nasi
Orbicularis oris
On each side will be seen :-The anterior condyloid foramen for the hypoglossal
nerve and a meningeal branch of the ascending pharyngeal artery.
The posterior condyloid fossa with the posterior condyloid foramen (this foramen
is not constant).
The sphenotic (middle lacerated) foramen and the orifice of the Vidian canal.
The canalis musculo-tubarius for the tensor tympani muscle and Eustachian
tube.
EXTERIOR OF THE SKULL
83
The carotid canal.
Aqueductus cochleæ, or ductus perilymphaticus.
The jugular foramen and fossa for the glosso-pharyngeal, vagus, and spinal
accessory nerves, the internal jugular vein, and a meningeal branch of the ascending
pharyngeal artery.
The tympanic canaliculus for Jacobson's nerve. (Tympanic of glosso-pharyngeal.)
FIG. 89. THE SKULL. (Norma facialis.)

OPHRYON
SUPERCILIARY RIDGE
GLABELLA
NASION
NASAL SINUS
SUBNASAL POINT
CANINE FOSSA
CANINE EMINENCE
ALVEOLAR POINT
The alar spine of the sphenoid; this is sometimes fifteen millimetres in length.
The glenoid fossa with the Glaserian fissure. This lodges the slender process
of the malleus, the tympanic twig of the internal maxillary artery. A small passage
beside it, the canal of Huguier, conducts the chorda tympani nerve from the
tympanum.
The external auditory meatus.
G 2

84
THE SKELETON
The auricular fissure for the tympanic branch of the vagus.
The tympanic plate and vaginal process.
The styloid process.
The stylo-mastoid foramen for the stylo-mastoid artery and the exit of the
facial nerve.
The mastoid process with the digastric and occipital grooves.
The sub-occipital region presents chiefly muscular ridges. They are the
superior, middle, and inferior nuchal lines, with the external occipital protuberance
and the external occipital crest. Behind the mastoid process is an opening of
variable size, the mastoid foramen; a branch of the occipital artery enters, and
a vein from the lateral sinus issues from this foramen.
The anterior aspect of the skull is oval in outline, but presents a very irregular
surface. Its upper portion, or forehead, presents the frontal eminences and super-
ciliary ridges. In the middle line is the prominence formed by the nasal bones,
with a deep pyramidal recess, the orbits, on each side. Below the nasal bones are
the entrances to the nasal sinuses and the various recesses connected with them.
The teeth form a conspicuous feature in this view of the skull, the outline of
which is completed by the mandible.
The bones visible in this view of the skull are: the frontal, nasals, lachrymals,
orbital surfaces of the lesser and the greater wings, and a portion of the body of the
sphenoid, the ossa plana of ethmoid, and the orbital processes of the palate bones,
the malars, maxillæ, inferior turbinals, and the mandible.
The foramina are: the supraorbital, infraorbital, optic, temporal, and mental;
the lachrymal duct; the malar and ethmoidal canals; and the spheno-maxillary
and sphenoidal fissures.
The orbits are two cavities of pyramidal shape, which lodge the eyeball and its
associated muscles, nerves, and vessels. The apex of each orbit corresponds to
the optic foramen, a circular orifice which transmits the optic nerve and ophthalmic
artery. The base looks forwards and outwards. It is formed by the frontal bone
above, the nasal process of the maxilla on the inner side, the malar bone
externally, and below by the malar and body of the maxilla. The following points
are seen around the base :-The suture between the external angular process of
the frontal bone and the malar; the supraorbital notch (sometimes a complete
foramen); and the suture between the frontal bone and the nasal process of the
maxilla; and in the inferior segment of the circumference is the malo-maxillary
suture. Occasionally, the infraorbital foramen opens by a narrow fissure into
the orbit.
The roof of the orbit is formed mainly by the orbital plate of the frontal bone,
and completed posteriorly by the lesser wing of the sphenoid. At the outer angle
it presents the lachrymal fossa for the lachrymal gland, and at the inner angle a
depression for the pulley of the superior oblique muscle.
The floor is formed by the orbital plate of the maxilla, the orbital process of the
malar, and the orbital process of the palate bone. At its inner angle it presents
the lachrymal canal, and near this a depression for the origin of the inferior oblique
muscle. The floor has a furrow for the infraorbital artery and the superior maxillary
division of the fifth nerve. The furrow terminates anteriorly in the infraorbital
canal, through which the infraorbital nerve and artery emerge on the face. Near
the commencement of the canal a narrow passage, the anterior dental canal, runs
forwards and downwards in the anterior wall of the antrum; it conducts nerves
to the incisor and canine teeth.
The outer wall is very oblique; it is formed by the orbital surface of the greater
wing of the sphenoid, and the malar. Between it and the roof, near the apex, is
the sphenoidal fissure, by means of which the third, fourth, ophthalmic division
of the fifth, and sixth nerves enter the orbit from the cranial cavity. The lower

THE ORBITS
85
margin of the fissure presents near the middle a small tubercle, from which one
head of the external rectus muscle arises. Between the outer wall and the floor,
near the apex, is the spheno-maxillary fissure, which allows the superior maxillary
nerve to enter the infraorbital groove from the spheno-maxillary fossa. At the
anterior margin of the fissure, the sphenoidal wing occasionally articulates with
the maxilla, but frequently it is excluded by the malar. In front of the anterior
extremity of this fissure is the orbital orifice of the malar canal. Near the outer
extremity of the sphenoidal fissure a few small foramina may be seen, especially
in old skulls, which allow branches of the middle meningeal artery to creep into
the orbit. A vertical fissure, the spheno-malar, traverses the outer wall. It
contains a very small foramen (the spheno-malar), which allows the temporal
branch of the orbital nerve to escape from the orbit. This foramen is sometimes
confined to the malar bone.
The inner wall, narrow and straight, is formed by the lachrymal, os planum
of the ethmoid, and a part of the body of the sphenoid. The ethmoid section of
the transverse suture contains the orifices of the anterior and posterior ethmoidal
FIG. 90.-THE INNER WALL OF THE ORBIT.


FRONTAL SINUS
NASAL BONE-
NASAL PROCESS OF MAXILLA.
LACHRYMAL
LACHRYMAL CANAL
ORIFICE OF ANTRUM
INFERIOR TURBINAL.
PALATE BONE
ANTERIOR NASAL SPINE
ANTERIOR ETHMOID CANAL
POSTERIOR ETHMOID CANAL
OPTIC FORAMEN
OS PLANUM OF ETHMOID
SPHENO-PALATINE FORAMEN
-VIDIAN CANAL, LEADING INTO
THE SPHENO-MAXILLARY FOSSA
SPHENOID
EXTERNAL PTERYGOID PLATE
PALATE BONE
canals: the former transmits the nasal nerve and anterior ethmoidal artery; the
latter the posterior ethmoidal artery.
Anteriorly is the lachrymal groove, and behind this the crest which gives
origin to the tensor tarsi. This wall has three vertical sutures: one between the
nasal process of the maxilla and the lachrymal, the ethmo-lachrymal, and one
between the os planum and body of the sphenoid. Occasionally the sphenoidal
turbinal bone appears in the orbit between the os planum of the ethmoid and the
body of the sphenoid (fig. 67).
The orbit communicates with the cranial cavity by the optic foramen and
sphenoidal fissure; with the nasal fossa by means of the lachrymal duct; with
the zygomatic and spheno-maxillary fosse by way of the spheno-maxillary fissure.
In addition to these large openings, the orbit has six other foramina-the infra-
orbital, malar, spheno-malar, anterior and posterior ethmoidal canals, and the
anterior dental canal-opening into it or leading from it.
In old skulls the frontal sinuses occasionally extend into that portion of the
horizontal plate of the frontal bone which forms the roof of the orbit.

86
THE SKELETON
The following muscles arise within the orbit: the four recti, the superior
oblique, and levator palpebra superioris, near the apex; the inferior oblique
on the floor of the orbit external to the lachrymal canal; and the tensor tarsi
from the lachrymal crest. The margins of the spheno-maxillary fissure give
attachment to the orbitalis muscle.
The nasal fossæ or sinuses are two irregular cavities situated on each side of
a median vertical septum, extending from the anterior part of the skull-base to the
superior surface of the hard palate. They are somewhat oblong in section, but
are narrower above than below.
Each fossa presents a roof, floor, inner and outer wall, and opens in front by
the anterior naris, and communicates behind with the pharynx by the posterior
naris.
The roof resembles that of a house with two sloping edges and an intermediate
level portion. The anterior slope is formed by the posterior surface of the nasal
bone and the nasal spine of the frontal. The horizontal portion corresponds to
the cribriform plate of the ethmoid and the sphenoidal turbinal. The posterior
FIG. 91. SECTION THROUGH THE NASAL FOSSA TO SHOW THE SEPTUM.
CREST OF SPHENOID:
CRISTA GALLI
NASAL SPINE OF FRONTAL
MESETHMOID
GROOVE FOR NASAL NERVE-
VOMER
CREST OF PALATE BONE.
SPINE OF PALATE BONE
CREST OF MAXILLA
slope is formed by the inferior surface of the body of the sphenoid, an ala of the
vomer, and a small portion of the sphenoidal process of each palate bone.
The floor is wider than the roof, concave from side to side, and has a slight
backward slope. It is formed mainly by the palatine process of the maxilla,
and completed posteriorly by the horizontal plate of the palate bone. Near its
anterior part, close beside the septum, is the anterior palatine canal.
The septum, or inner wall, is formed by the crest of the sphenoid, the crest of
the nasal bones, nasal spine of frontal, the mesethmoid, vomer, and the median
crest formed by the apposition of the palatine plates of the maxillæ and the hori-
zontal plates of the palate bones. The anterior border has a triangular outline,
limited above by the mesethmoid, and below by the vomer. This receives the
triangular cartilage of the nose. The posterior border is formed by the pharyngeal
edge of the vomer. The septum is usually deflected to one side, and is occasionally
perforated. Sometimes a strip of cartilage, continuous with the triangular cartilage,
persists between the vomer and mesethmoid.
The outer wall is formed by the nasal process and inner wall of the maxilla,
the lachrymal, the ethmoidal and inferior turbinals, the vertical plate of the palate

THE NASAL FOSSE
87
bone, and the inner surface of the internal pterygoid plate. The outer wall presents
three recesses or meatuses. The superior meatus is situated between the superior
and middle turbinal; it opens posteriorly; three orifices are in relation with it,
namely, the orifice of the posterior ethmoidal cells, the spheno-palatine foramen,
and the opening of the sphenoidal sinus. The middle meatus lies between the
middle and inferior turbinals. It opens anteriorly and posteriorly. This meatus
has two orifices communicating with it-the opening of the antrum (which is of
very irregular shape) and the termination of the infundibulum. The inferior
meatus is situated between the inferior turbinal and the floor of the fossa; it
presents near its anterior part, under cover of the turbinal, the terminal orifice of
the nasal duct. This is the largest meatus, and, like the middle, opens anteriorly
and posteriorly.
The anterior narial orifices are bounded above by the lower border of the nasal
bones, laterally by the maxillæ, and inferiorly by the premaxillary portions of the
maxillæ. In the recent state they are separated by the triangular cartilage; in the
dried skull the most anterior inferior limit is the anterior nasal spine.
FIG. 92. SECTION THROUGH THE NASAL FOSSA TO SHOW THE OUTER WALL
WITH THE MEATUSES.

BODY OF SPHENOID
SPHENOIDAL SINUS
SPHENO-PALATINE FORAMEN
MIDDLE MEATUS
INTERNAL PTERYGOID PLATE
PALATE BONE
CRISTA GALLI
FRONTAL SINUS
SUPERIOR TURBINAL
MIDDLE TURBINAL
INFUNDIBULUM
INFERIOR TURBINAL
INTERIOR NASAL SPINE
ANTERIOR PALATINE FORAMEN
The posterior narial orifices are bounded above by the alæ of the vomer, the
sphenoidal process of the palate bones, and the under surface of the sphenoid;
externally by the internal pterygoid plates; and inferiorly by the posterior border
of the horizontal plates of the palate bones. They are divided by the posterior
border of the vomer and the posterior nasal spine.
The nasal fossæ communicate with all the more important fossæ and sinuses of
the skull. By means of the foramina in the roof they are in connection with the
cranial cavity. The infundibulum brings each fossa in communication with the
frontal and anterior ethmoidal cells. The posterior ethmoidal and the sphenoidal
cells open into the superior meatuses. The spheno-palatine foramina connect them
with the spheno-maxillary fossæ, and an irregular orifice in each outer wall causes
them to communicate with the antra. The nasal ducts connect them with the
orbits, and the anterior palatine canals with the buccal cavity.
The sutures visible in an anterior view of the skull are numerous, and for the
most part unimportant:-
The transverse suture extends from one external angular process to the other.

88
THE SKELETON
The upper part of the suture is formed by the frontal bone; below are the malar,
greater and lesser wing of the sphenoid, os planum, lachrymal, maxillary, and nasal
bones. A portion of this complex suture, lying between the sphenoid and frontal
bones, appears in the anterior cranial fossa.
Other and less important fissures are the internasal, naso-maxillary, inter-
maxillary, and malo-maxillary. The small sutures visible in the orbit have been
already mentioned in describing that cavity.
FIG. 93. THE POSTERIOR NARES.
VIDIAN CANAL
SCAPHOID FOSSA
PTERYGOID FOSSA
EXTERNAL PTERYGOID PLATE
TUBEROSITY OF PALATE BONE
PTERYGO-PALATINE CANALS
FORAMEN OVALE
SPINE OF PALATE OR POSTERIOR
NASAL SPINE
VOMER
INTERNAL PTERYGOID PLATE
HAMULAR PROCESS
The following points are seen in an anterior view of the cranium :-
The glabella, a smooth space between the converging superciliary ridges.
The ophryon is the most anterior point of the metopic suture.
The nasion is the central point of the transverse suture.
The subnasal point is the middle of the inferior border of the anterior nasal
aperture at the base of the nasal spine.
The alveolar point is the centre of the anterior margin of the upper alveolar
arch.
THE INTERIOR OF THE SKULL
In order to study the interior of the skull it is necessary to make sections in
three directions,-sagittal, coronal, and horizontal. This enables the student to
examine the various points with facility, and displays the great proportion the
brain cavity bears to the rest of the skull. The sagittal section should be made
slightly to one side of the median line in order to preserve the nasal septum. The
black line (fig. 94) drawn from the basion (anterior margin of the foramen magnum)
to the gonion (the anterior extremity of the sphenoid) represents the basi-cranial
axis; whilst the line drawn from the gonion to the subnasal point lies in the
basi-facial axis. These two axes form an angle termed the cranio-facial, which
is useful in making comparative measurements of crania. A line prolonged
vertically upwards from the basion will strike the bregma. This is the basi-
bregmatic axis, and gives the greatest height of the cranial cavity. A line drawn
from the ophryon to the occipital point indicates the greatest length of the cranium.
Near its middle, the cranial cavity is encroached upon by the petrosal; the

INTERIOR OF THE SKULL
89
walls are channelled vertically by narrow grooves for the middle and small meningeal
arteries, and towards the base broader furrows are found for the venous sinuses.
The coronal section is most instructive when made in the basi-bregmatic axis.
The section will pass through the petrosal in such a way as to traverse the two
external auditory passages and expose the tympanum and vestibule, and will also
partially traverse the internal auditory meatuses. Such a section will divide the
parietal bones slightly posterior to the parietal eminences, and a line drawn
transversely across the section at the mid-point will give the greatest transverse
measurement of the cranial cavity. A skull divided in this way facilitates the
examination of the parts about the posterior nares.
The horizontal section of the skull should be made through a line extending
from the ophryon to the occipital point, passing laterally a few millimetres above
the pterion on each side. It is of great advantage to study the various parts on
FIG. 94. THE SKULL IN SAGITTAL SECTION.

BREGMA
OCCIPITAL
POINT
BASION
OPHRYON
SUB-NASAL
POINT
the floor of the cranial cavity in a second skull having the dura mater and its
various processes in situ.
The floor of the cranial cavity presents three irregular depressions termed the
anterior, middle, and posterior fossæ.
The anterior fossa.-The floor of this fossa is on a higher level than the rest
of the cranial floor. It is formed by the horizontal plate of the frontal bone, the
cribriform plate of the ethmoid, and the lesser wings of the sphenoid, which meet
each other and exclude the pre-sphenoid from the anterior fossa. The free margins
of the lesser wings and the optic groove mark the limits of this fossa posteriorly.
The central portion of the fossa is depressed on each side of the crista galli, the
depressions forming a part of the roofs of the nasal sinuses; laterally, the floor of
this fossa is convex where it corresponds to the roof of the orbits, and is marked
by irregular furrows. It supports the frontal lobes of the cerebrum. The sutures
traversing the floor of the fossa are the fronto-ethmoidal, forming three sides of a
rectangle, that portion of the transverse facial suture which traverses the roof of
90
THE SKELETON
FIG. 95.-THE SKULL IN HORIZONTAL SECTION.

ETHMOIDAL FISSURE FOR NASAL NERVE
ANTERIOR ETHMOIDAL CANAL (FOR NASAL
NERVE)
ETHMOIDAL FORAMINA FOR OLFACTORY NERVE
OPTIC FORAMEN (FOR SECOND OR OPTIC
NERVE)
FORAMEN ROTUNDUM (SECOND DIVISION OF
FIFTH NERVE)
FORAMEN OVALE (THIRD DIVISION OF FIFTH
NERVE)
NOTCH FOR SIXTH NERVE
DEPRESSION FOR FIFTH NERVE
HIATUS FALLOPII
INTERIOR AUDITORY MEATUS (SEVENTH AND
EIGHTH NERVES)
JUGULAR FORAMEN (NINTH, TENTH, AND
ELEVENTH NERVES)
ANTERIOR CONDYLOID FORAMEN (TWELFTH
.NERVE)

INTERIOR OF THE SKULL
91
FIG. 96.-THE SKULL IN HORIZONTAL SECTION.
FRONTAL BONE
RIDGE FOR FALX CEREBRI
CRISTA GALLI
ANTERIOR FOSSA
CRIBRIFORM PLATE'
LESSER WING OF SPHENOID
OPTIC GROOVE
PITUITARY FOSSA
DORSUM EPHIPPII
PETRO-SPHENOIDAL PROCESS
MIDDLE FOSSA
THE CLIVUS
FORAMEN MAGNUM
POSTERIOR FOSSA
INTERNAL OCCIPITAL CREST
INTERNAL OCCIPITAL PROTUBERANCE
OCCIPITAL BONE
92
THE SKELETON

the orbit, and the ethmoido-sphenoidal suture, the centre of which corresponds to
the gonion. The points of interest in the fossa are:-
A groove for the superior longitudinal sinus.
The foramen cæcum which transmits a small vein.
The crista galli.
The ethmoidal fissure for the nasal branch of the fifth nerve.
The cranial orifice of the anterior ethmoidal canal, transmitting the nasal
branch of the fifth and a meningeal branch of the anterior ethmoidal artery.
Ethmoidal foramina for the olfactory filaments.
Cranial orifice of the posterior ethmoidal canal, transmitting a meningeal branch
of the posterior ethmoidal artery.
The ethmoidal spine of the sphenoid.
Furrows for meningeal arteries.
The middle cranial fossa presents a central isthmus and two lateral depressed
portions. It is limited anteriorly by the posterior border of the lesser wings of the
sphenoid and the anterior margin of the optic groove. The posterior limits are the
dorsum ephippii and the superior border of the petrosals. Laterally it is bounded
by the squamosals and the parietal bones. The floor is formed by the body
and greater wings of the sphenoid, and the anterior surface of the petrosal. It
contains the following sutures: spheno-parietal, petro-sphenoid, squamo-sphenoidal,
squamous, and a portion of the transverse suture. The central portion or isthmus
of the middle fossa possesses the following points from before backwards :-
The optic groove, which lodges the optic chiasma.
The optic foramina, transmitting the optic nerve and ophthalmic artery.
The olivary process, indicating the line of ankylosis between pre- and post-
sphenoid.
The anterior clinoid processes.
The pituitary fossa, with the middle clinoid processes, and grooves for the
internal carotid arteries. The dorsum ephippii, with the posterior clinoid processes,
and notches for the third pair of cranial nerves.
This central depression is in direct relation with the parts of the brain sur-
rounding the circle of Willis.
The lateral depressions receive the temporo-sphenoidal lobes of the brain,
and are marked by numerous furrows roughly corresponding to the convolutions
of the cerebrum. Numerous narrow diverging channels pass upwards from the
fossa towards the vertex; these lodge the ramifications of the middle and small
meningeal arteries.
The following openings occur on each side of this fossa :-
The sphenoidal fissure, leading into the orbit and transmitting the third, fourth,
ophthalmic division of the fifth, the sixth nerve, and ophthalmic vein.
In the greater wing of the sphenoid near its union with the frontal bone there
are small openings allowing twigs of the middle meningeal artery to enter the orbit.
The foramen rotundum, which conducts the second division of the fifth nerve
into the spheno-maxillary fossa.
The foramen ovale: this transmits the third division of the fifth with its motor
root, the small meningeal artery, and the small superficial petrosal nerve.
The foramen Vesalii (not always present) for a small vein.
The foramen spinosum, for the middle meningeal artery and its venæ comites.
The sphenotic foramen (middle lacerated foramen), which transmits at its inner
angle the internal carotid artery, with the carotid plexus of nerves.
On the posterior wall of this fossa the objects of interest are:-
A depression which lodges the Gasserian ganglion.
The hiatus Fallopii, for the great superficial petrosal nerve, and a twig from
the middle meningeal artery.


INTERIOR OF THE SKULL
93
A foramen for the small superficial petrosal nerve.
An eminence formed by the superior semicircular canal.
Anterior and slightly external to the ridge formed by the superior semicircular
canal, the bone is exceedingly thin and translucent. This is the roof of the
tympanum (tegmen tympani). When the dura mater is in situ, the depression lodging
the Gasserian ganglion is converted into a foramen, traversed by the fifth nerve.
The notch in the side of the dorsum ephippii for the third nerve is also a foramen
when the dura mater is present. In many skulls the middle clinoid process
is pro-
longed to meet the anterior clinoid process, and thus forms a foramen for the
internal carotid artery. The grooves for the middle meningeal arteries are some-
times canals or tunnels in a part of their course, especially in old skulls. The
grooves radiate from the foramen spinosum and extend to the vault. The bones
most deeply marked are the squamosal, the greater wing of the sphenoid, and the
parietal.
The posterior cranial fossa is the deepest portion of the cavity. It is bounded
by the dorsum ephippii and the superior borders of the petrosals; the mastoid
portion of the petrosals, the posterior inferior angle of the parietals, and the squamo-
occipital below the level of the crest (supra-occipital). The upper limits are
indicated by the grooves for the lateral sinuses. It is marked by the following
sutures: the petro-occipital, occipito-mastoid, parieto-mastoid, and, in young
skulls, the basilar suture.
The ridges limiting this fossa give attachment to the tentorium cerebelli,
and the fossa lodges the cerebellum with the pons and medulla. It communicates
with the general cranial cavity by means of the foramen of Pacchionius when the
tentorium is in situ.


It has the following objects of interest :-
The clivus, extending from the dorsum ephippii to the anterior margin of the
foramen magnum. This is in relation with the basilar artery, the pons, and
medulla.
The notch for the sixth nerve on each side of the dorsum ephippii. This is
sometimes a foramen, termed the petro-sphenoid.
The foramen magnum, presenting on each side a tubercle for the check ligaments;
and the anterior condyloid foramen (sometimes subdivided by a spiculum of bone)
for the hypoglossal nerve. Behind the foramen there is a vertical ridge of bone,
the internal occipital crest, for the falx cerebelli. This sometimes presents a
depression known as the vermiform fossa.
The anterior boundaries of the fossa present:
A notch for the passage of the fifth nerve.
tentorium is present.
This is a foramen when the
The internal auditory meatus, for the facial and auditory nerves, and the
auditory branch of the basilar artery.
The jugular foramen, which transmits the glosso-pharyngeal, vagus, and spinal
accessory nerves, the internal jugular vein, and the meningeal branch of the
ascending pharyngeal artery.
The termination of the groove for the lateral sinus, with the internal orifice of
the mastoid foramen.
The cranium of an average European has a capacity of 1450 cc. The circum-
ference, taken in a plane passing through the ophryon anteriorly, the occipital
point posteriorly, and the pterion laterally, is 52 cm. The length from the ophryon
to the occipital point is 17 cm. ; the width between the parietals at the level of
the zygomata is 12.5 cm. ; and the height from the basion to the bregma is
nearly the same. The cranio-facial angle is about 96°.

94
THE SKELETON
THE TEETH
An adult individual with perfect dentition possesses thirty-two teeth, equally
distributed to the maxilla and mandible. The four central teeth in each dental
arch are termed incisors; the tooth next these on each side is the canine; behind
these are two pre-molars or bicuspids; and lastly, three molars. This relation of
teeth is expressed by means of a formula :-
1
I C prm m = 32.
2 1
2 3
2 3
Each tooth has a portion coated with enamel exposed above the gum-named
the crown; and a portion coated with cementum embedded in bone-this is the
root. The line of union of the crown and root is termed the neck.
FIG. 97. THE TEETH OF AN ADULT.
INCISORS
CANINE
BICUSPIDS
MOLARS
WISDOM TOOTH
UPPER
SET
88
LOWER
SET
The surface of the tooth directed towards the lips and cheek is called labial,
and that towards the tongue lingual. It is also necessary to apply definite terms
to the opposed surfaces of teeth, hence the surface directed towards the middle line
of the mouth if the alveolar arch were straightened out is median, and the opposite
side is distal. Each tooth has distinguishing features.
The incisors.-The central upper incisors are very much larger than the lateral,
the crown is somewhat oblong in outline, its length exceeding the breadth. The
median is longer than the distal border. The labial surface is convex, the lingual
concave, and terminates near the gum in a low eminence, the basal ridge or
cingulum. In recently erupted teeth, the cutting edge is elevated into three small
cusps; these soon wear down and leave a straight edge. The root is long, single,
and flattened laterally.
The upper lateral incisors are much smaller than the centrals, which they
resemble in the general contour of the crown. The distal angle of the crown is
more rounded than in the central incisors, and the cingulum is more pronounced.
The root is single.
The lower central incisors are much narrower than those of the upper set, and
less than half their width in the cutting edges, and the crown becomes contracted
THE TEETH
95
towards the neck. The cingulum is scarcely marked, and the root single. The
lower lateral incisors are distinctly larger than the lower centrals in every direction.
The distal angle of the crown is rounded off; the root is single and frequently
presents on each side a longitudinal groove.
The canines. These differ from the incisors in possessing larger crowns,
and thick long roots. The crown ends in a blunt point, and the cutting edge
slopes away on each side.
The slope toward the bicuspid is the longer, and
causes the crown to be asymmetrical. The lingual surface presents a median
and two lateral ridges; they converge towards the well-marked cingulum, which
is often produced into a distinct cusp.
The lower canines have not such pronounced features as the upper; the point
is blunter, and the median ridge is absent from the lingual surface.
Premolars or bicuspids.-The crown of the first upper premolar has a grinding
surface which is somewhat quadrilateral in outline; the labial is, however, longer
than the lingual border. It has two cusps, of which the labial is much the larger.
The cusps are separated by a pit, but are connected by a narrow ridge along the
median and distal borders. The median border is nearly straight, the distal is
The root may be single, or marked by a longitudinal depression, or be
double throughout the greater part of its length; it may in some specimens have
three distinct roots like a molar.
convex.
FIG. 98.-A MOLAR TOOTH IN SECTION, AND A CANINE TOOTH.
CROWN
CUSP
ROOT
NECK
PULP
CAVITY
ROOT
NECK
CINGULUM

CROWN
The second bicuspid differs from the first in having its cusps nearly equal in
size. Its root is double.
The lower bicuspids are smaller than the upper and differ from them in shape.
The labial cusp is larger than the lingual; the cusps are connected by a low ridge,
the grinding surface presents two small pits. The root is single, rounded, and
tapering.
The second lower bicuspid is larger than the first. The inner cusp is higher
and stouter, and the distal border is much more pronounced. Its root is also
single and tapering.
The upper molars.-The first and second resemble each other so closely that
one description will serve for the two. The grinding surface is quadrilateral but
with rounded angles. It has four cusps, two labial and two lingual. Of these,
the anterior lingual is the largest, and is connected with the posterior labial by a
ridge of enamel. The groove separating the labial and lingual cusps extends on
to the sides of the crown and is lost near the neck. The median and distal
borders usually present a slight ridge. The roots are three in number, two on the
labial, and one on the lingual aspect; this last is usually referred to as the
palatine root, and often diverges from the crown at a considerable angle.
The lower molars.-The first is the most constant in form. It has five cusps
on the grinding surface. Four occupy the angles and are separated by a crucial
fissure. The fifth cusp is situated at the posterior extremity of the longitudinal
ridge. It has two roots, placed one in front of the other; they are inclined somewhat

96
THE SKELETON

backwards, and present a vertical groove which is sometimes so deep as to
divide each root, producing four roots. One root only may divide in this way.
The second molar differs from the first in the frequent absence of the fifth
cusp; when present it is feebly developed. The roots have a tendency to become
confluent.
The third molars (wisdom teeth).-The upper third molar resembles in its
grinding surface the adjacent molars. The two lingual tubercles are usually
blended, and the roots coalesce and taper to a cone. The apex is often bent.
The characters of this tooth are very variable.
The third lower molar has a larger crown than the corresponding tooth in the
upper set; it resembles the adjacent molars and has usually five cusps. It has
two roots which may be confluent.
The Relations of the Crowns of the Upper and Lower Teeth to each other.-
In a normal condition the upper teeth form a larger arch than the lower. The
upper incisors and canines close in front of the lower; occasionally they fall upon,
but rarely fall behind them. The labial tubercles of the bicuspids and molars
FIG. 99-THE TEMPORARY TEETH.
INCISORS
CANINE
MILK MOLARS
UPPER SET
LOWER SET
of the lower jaw are received in the depressions between the labial and lingual
tubercles of the upper set of teeth; hence the labial tubercles of the upper overlap
the corresponding tubercles in the lower teeth.
In consequence of the difference in width of the crowns of the upper and lower
incisors, it happens that in closure of the mouth each tooth impinges upon two
teeth.
The milk teeth.-These are smaller in number and size than the teeth of the
permanent set. The formula is :-
12/01/m
2
2
= 20.
The temporary teeth are smaller than their successors; the enamel of the crown
terminates in a thick edge; and the tubercles on the crowns of the molars are less
regular and pronounced.
The incisors are similar to those of the permanent set, but the canines have
shorter and broader crowns than their successors.
THE SKULL
97
THE MORPHOLOGY OF THE SKULL
In Man the skull during development passes through three stages. At first the brain
vesicles are enclosed in a sac of indifferent tissue which ultimately becomes tough and
fibrous. This, the membranous cranium, is represented in the adult by the dura mater.
Gradually the sides and base of the membranous cranium become cartilaginous: in due
course osseous tissue appears in the membranous tracts, and later in the cartilage.
Eventually an osseous box is formed, consisting of membrane-bones and cartilage-bones
intricately interwoven.
A study of the skull in the chondral stage is very instructive. It consists of two parts:
ni (1) The skull proper; and (2) the appendicular elements.
The skull proper consists of three regions:-
The basi-cranial or notochordal region, which ultimately gives rise to the chief parts of
the occipital bone.
Anterior to this is the trabecular region, from which the sphenoid is subsequently
developed.
The most anterior portion is the ethmo-vomerine region, from which the nasal septum
and its associated cartilages arise. Wedged in on each side between the basi-cranial and
trabecular regions is the complicated periotic capsule.
The appendicular elements of the cranium are a number of cartilaginous rods, which
FIG. 100. THE CHONDRO-CRANIUM.

ETHMOID CARTILAGE
OPTIC FORAMEN
FORAMEN ROTUNDUM
FORAMEN OVALE
HIATUS FALLOPII
INTERNAL AUDITORY MEATUS
JUGULAR FORAMEN
ANTERIOR CONDYLOID FORAMEN
CONDYLES
MEMBRANE
O
NASAL CARTILAGES
CRISTA GALLI
ORBITO-SPHENOID
ALI-SPHENOID
PERIOTIC CAPSULE
AQUEDUCTUS VESTIBULI
FLOCCULAR FOSSA
MASTOID FORAMEN
OCCIPITAL CARTILAGE
undergo a remarkable metamorphosis, and, in the adult, are represented by the ear-bones,
the styloid process, and the hyoid.
The chondro-cranium at the third month presents the following parts. Seen from above,
the cartilage extends from the cranial base to a spot midway between the base and the vertex,
shading off indefinitely on the dura mater. The conspicuous oval masses on each side are
the periotic cartilages, in which the floccular fosse are conspicuous objects. Each periotic
cartilage is joined to the sphenoid by a strip, termed the sphenotic cartilage, which usually
persists in the adult skull. At this date the cartilage for the orbito-sphenoid (the so-called
lesser wing) is co-extensive with the ali-sphenoid, and forms part of the lateral wall of the
skull. The snout-like appearance of the anterior part of the skull is caused by the fronto-
nasal plate. On each side of the ethmo-vomerine plate near its anterior termination there
are two small concave pieces of cartilage for Jacobson's organ. They are sometimes
referred to as the ploughshare cartilages owing to their shape.
The Metamorphosis of the Branchial Bars
These rods of cartilage are named, from before backwards, the mandibular, hyoid, and
thyroid bars. They may with care be easily dissected in the foetus between the third and
fourth months. Their metamorphosis is as follows:-
The two extremities of the mandibular bar ossify; the distal end ultimately forms that
H

98
THE SKELETON
portion of the mandible adjacent to the symphysis; the proximal end ossifies as the
malleus. The intermediate portion disappears; the only vestige which remains is a band
of fibrous tissue, the spheno-mandibular ligament, extending from the spine of the sphenoid
to the spine of the mandible.
The hyoid bar fuses distally with the thyroid bar, and is represented by the hyoid bone.
Its proximal end becomes the incus, tympano-hyal, and styloid process; the intervening strip
is represented in the adult by the stylo-hyoid ligament.
The styloid process has two centres of ossification. A nucleus appears anterior to the
stylo-mastoid foramen, and is known as the tympano-hyal. At birth the true styloid
process is cartilaginous. In the second year it ossifies, and subsequently becomes firmly
ankylosed to the tympano-hyal. Occasionally the hyoid bar may ossify throughout. When
this is the case the styloid process reaches to the hyoid and replaces the stylo-hyoid
ligament.
The stapes originates in a piece of cartilage which is traversed by the temporary
stapedial artery. Its centres of ossification require investigation. The internal pterygoid
plate arises in a piece of cartilage which represents the palato-quadrate of lower vertebrates.
The internal pterygoid plate is an appendicular element engrafted on to the sphenoid.
In many mammals it is a separate bone throughout life. In the same way the styloid
process is an appendicular element ankylosed to the petrosal and the tympanic plate; in
many mammals it remains separate throughout life.
The Skull at Birth
The skull at birth presents, when compared with the adult skull, several important and
interesting features. Its peculiarities may be considered under three headings:-The
peculiarities of the foetal skull as a whole; the condition of individual bones; the
remnants of the chondral skull.
FIG. 101. THE CRANIUM AT BIRTH.
The general characters of the foetal skull. The most striking features of the skull at
birth are, its relatively large size in comparison with the body, and the predominance of
the cerebral over the facial portion of the skull; the latter is, in fact, very small.
The frontal and parietal eminences are large and conspicuous; the sutures are absent;
the adjacent margins of the bones of the vault are separated by septa of fibrous tissue
continuous with the dura mater internally and the pericranium externally; hence it is
difficult to separate the roof bones from the underlying dura mater, each bone being lodged
as it were in a dense membranous sac. The bones of the vault consist of a single layer

MORPHOLOGY OF THE SKULL
99
without any diploë, and their cranial surfaces present no digital impressions. Six mem-
branous spaces exist, named fontanelles: two are median, named anterior and posterior;
and two exist on each side, termed anterior and posterior lateral fontanelles. Each angle
of the parietal bones is in relation with a fontanelle. The anterior fontanelle is lozenge-
shaped, the posterior triangular. The lateral fontanelles are irregular in outline.
FIG. 102.-THE CRANIUM AT BIRTH.
FIG. 103. THE CRANIUM AT BIRTH IN SAGITTAL SECTION.
Turning to the base of the skull, the most striking points are the absence of the mastoid
processes and the large angle which the pterygoid plates form with the skull base, whereas
in the adult the angle is almost a right one. The base of the skull is relatively short, and
the lower border of the mental symphysis is on a level with the occipital condyles.
H 2

100
THE SKELETON
The facial skeleton is relatively small in consequence of the small size of the nasal
fossæ; these are as wide as they are high, and are almost filled with the turbinals.
The Peculiarities of Individual Bones at Birth.
The occipital consists of four distinct parts: the basi-occipital, two ex-occipitals, and the
squamo-occipital; these four parts are united by hyaline cartilage. Compared with the
adult bone, the following are the most important points of distinction:-There is no
FIG. 104. THE OCCIPITAL AT BIRTH.
INTERPARIETAL PORTION
(DEVELOPS IN MEMBRANE)
INTERPARIETAL AND
THE
SUPRA-OCCIPITAL
POR-
TIONS FORM THE SQUAMO-
OCCIPITAL OF THE ADULT
SUPRA-OCCIPITAL PORTION
(DEVELOPS IN CARTILAGE)
EX-OCCIPITAL
FORAMEN
MAGNUM
BASI-OCCIPITAL
pharnygeal tubercle or jugular process; the squamo-occipital presents two deep fissures
separating the interparietal from the supraoccipital portion, and extending nearly as far
inwards as the occipital protuberance. The grooves for the lateral sinus are absent.
The sphenoid in a macerated foetal skull falls into three pieces. The main portion
consists of the united pre- and post-sphenoid with the orbito-sphenoids and lingulæ. The
VIDIAN CANAL
FIG. 105.-THE SPHENOID AT BIRTH.
LINGULA
pre-sphenoid is quite solid and connected with the ethmo-vomerine cartilage, and presents
no traces of the air sinuses which occupy this part in the adult skull. The pre-sphenoid
by its upper surface forms part of the anterior cranial fossa, from which it is subsequently
excluded by the orbito-sphenoids. The optic foramina are large and triangular in shape.
MORPHOLOGY OF THE SKULL
101
The lingulæ stand out from the basi-sphenoid as two lateral buttresses, and the floor of
the sella turcica presents the cranio-pharyngeal canal, which in a recent bone is occupied
by fibrous tissue. The dorsum ephippii is yet cartilaginous. The ali-sphenoids with the
pterygoid processes are separated from the rest of the bone by cartilage. The foramen
rotundum is complete, but the future foramen ovale is merely a deep notch in its posterior
border, and there is no foramen spinosum. The pterygoid processes are short, and each
internal pterygoid plate presents a broad surface for articulation with the lingulæ. The
Vidian canal is a groove between the internal pterygoid plate, the lingula, and greater wing.
FIG. 106. THE TEMPORAL BONE AT BIRTH.

SQUAMOSAL
TYMPANIC.
PETROSAL
The temporal bone at birth consists of three parts (excluding the ear-bones): the petrosal,
squamosal, and tympanic. The petrosal presents a large and conspicuous floccular fossa;
the hiatus Fallopii is a shallow bay lodging the geniculate ganglion of the facial nerve.
There is a relatively large mastoid antrum, but no mastoid process. The styloid process
is unossified, but the tympano-hyal may be detected as a minute rounded nodule of bone
near the stylo-mastoid foramen.
The squamosal has a very shallow glenoid fossa and a relatively large post-glenoid
tubercle. The posterior part of the inferior border is prolonged downwards into an uncinate
process to close externally the mastoid antrum.

FIG. 107. THE TEMPORAL BONE AT BIRTH. (Outer view.)
POST-GLENOID TUBERCLE
GLASERIAN FISSURE.
TYMPANIC ANNULUS
SQUAMOSAL
-PETRC-SQUAMOUS SUTURE
- PETROSAL
STYLO-MASTOID FORAMEN
TYMPANO-HYAL
CAROTID CANAL
The tympanic bone or annulus is a delicate horseshoe-shaped ossicle, attached by its
anterior and posterior horns to the inferior border of the squamosal.
The ear-bones are chiefly of interest from their size, for they are as large at birth as in
the adult. The processus gracilis (Folian process) may be 2 cm. in length.
The frontal consists of two bones separated by a median vertical (metopic) suture.
The frontal eminence is very conspicuous, but the superciliary ridges and frontal sinuses
are wanting. The nasal spine, which later becomes one of the most conspicuous features
of this bone, is absent. There is no temporal ridge.
The parietal is simply a quadrilateral lamina of bone, concave on its inner and

102
THE SKELETON
convex on the outer surface. The parietal eminence, which indicates the spot in which
the ossification of the bone commenced, is large and conspicuous. The grooves for blood-
sinuses, as in other cranial bones, are absent. Each angle of the parietal is in relation
with a fontanelle. As in the adult, the anterior inferior angle of the bone is prolonged
downwards towards the ali-sphenoid.
The ethmoid consists of two lateral portions separated by the still cartilaginous ethmo-
vomerine plate. The ethmoid cells are represented by shallow depressions, and the
uncinate process is undeveloped.
FIG. 108.-TEMPORAL BONE AT BIRTH. (Inner view.)
HIATUS FALLOPII
FLOCCULAR FOSSA
AQUEDUCTUS VESTIBULI
INTERNAL AUDITORY MEATUS
The sphenoidal turbinals are two small triangular pieces of bone lying in the peri-
chondrium on each side of the ethmo-vomerine plate near its junction with the pre-
sphenoid. (Indicated by the * in fig. 103.)
The maxilla presents the following characters :-The maxillo-premaxillary suture is
visible on the palatine aspect of the bone. The alveolar border presents five sockets for
teeth. The infraorbital foramen communicates with the floor of the orbit by a deep
fissure; this fissure sometimes persists in the adult. The antrum is a shallow groove.
The mandible at birth consists of two halves united by fibrous tissue in the line of the
future symphysis. Each half is a bony trough lodging teeth. The trough is divided by
thin osseous partitions into five compartments: of these, the fifth is the largest, and is
often subdivided by a ridge of bone. The floor is traversed by a furrow as far forward
FIG. 109. THE FRONTAL AT BIRTH.
as the fourth socket (that for the first milk molar), where it turns outwards at the
mental foramen. This furrow lodges the mandibular (inferior dental) nerve and artery,
which enter by the large mandibular foramen. The condyle is on a level with the mental
extremity of the bone.
The palate bones differ mainly from the adult bone in that the vertical and horizontal
plates are of the same length; thus the nasal fossæ in the foetus are as wide as they are
high, whereas in the adult the height of each nasal fossa greatly exceeds the width.

MORPHOLOGY OF THE SKULL
103
Concerning the remaining bones little need be said. The vomer is a delicate trough of
bone for the reception of the inferior border of the ethmo-vomerine plate; its inferior
border, that which rests upon the palate, is broad, and the bone presents quite a different
appearance to the adult vomer. The nasal bones are short but broad; the malar and
inferior turbinals are relatively very large; and the lachrymals are thin, frail, and delicate
lamellæ.
The hyoid consists of its usual five parts. There is a median nucleus for the basi-
hyal, and one on each side for the greater cornua (thyro-hyals). The lesser cornua are
cartilaginous.
FIG. 110. THE MAXILLA AT BIRTH.

PRE-MAXILLARY PORTION

Outer view.
Inferior view.
Inner view.

Remnants of the cartilaginous cranium. It has already been pointed out that at an early
date the base of the skull and the face are represented by hyaline cartilage, which for the
most part is replaced by bone before birth. Even at birth remnants of this primitive chon-
dral skull are abundant. In the cranium, cartilaginous tracts exist between the various
portions of the occipital bone, as well as at the line of junction of the occipital with the
petrosal and sphenoid. The dorsum ephippii is entirely cartilaginous at birth, and the
last portion of this cartilage disappears with the ankylosis of the basi-occipital and
basi-sphenoid about the twenty-fifth year. A similar strip of cartilage lying between the
jugular process and the jugular surface of the petrosal persists until late in life. A strip
FIG. 111. THE MANDIBLE AT BIRTH.
OUTER VIEW
INNER VIEW
of cartilage unites the ali-sphenoids with the lingulæ, and for at least a year after birth
this cartilage is continuous with that which throughout life occupies the sphenotic (middle
lacerated) foramen. A strip of cartilage exists along the posterior border of the orbito-
sphenoid, and not infrequently extends outwards to the pterion. In the adult skull it
is replaced by ligamentous tissue.
The ethmo-vomerine plate is entirely cartilaginous, and near the end of the nose sup-
ports the lateral nasal cartilages, remnants of the fronto-nasal plate. The fate of the
ethmo-vomerine plate is instructive. The upper part is ossified to form the mesethmoid;
the lower part atrophies from the pressure exerted by the vomer; the tip remains as the

104
THE SKELETON
triangular cartilage. The lateral snout-like extremities of the fronto-nasal plate persist as
the lateral cartilages of the nose.
Among the appendicular elements of the skull, the styloid process and a large portion
of the hyoid are cartilaginous at birth.
The Nerve-foramina of the Skull
The various foramina and canals in the skull which give passage to nerves may be
arranged in two groups, primary and secondary. Primary foramina indicate the spots
where the nerves quit the general cavity of the dura mater, and as this membrane indi-
cates the limit of the primitive cranium, a cranial nerve, in a morphological sense, becomes
extra-cranial at the point where it pierces this membrane. In consequence of the com-
plicated and extraordinary modifications the vertebrate skull has undergone, many nerves
traverse, in the adult skull, bony tunnels and canals which are not represented in the less
complex skulls of low vertebrates such as sharks, rays, &c. To such foramina and canals
the terms secondary or adventitious may be applied.
Nerve-foramina are further interesting in that they occupy sutures, or indicate the
points of union of two or more ossific centres. To this rule the foramen rotundum is the
only exception in the human skull.
The Primary Foramina
1. Foramen magnum. This is bounded by four distinct centres, the supra-, basi-, and two
ex-occipitals. It transmits the spinal accessory nerve, the vertebral artery and its
anterior and posterior spinal branches, the spinal cord and its membranes.
2. The anterior condyloid.-At birth this is a deep notch in the anterior extremity of
the ex-occipital, and becomes a complete foramen when the basi- and ex-occipitals fuse.
Occasionally it may be complete in the ex-occipital, but it indicates accurately the line
of union of these two elements of the occipital bone. It transmits the hypoglossal nerve,
the meningeal branch of the ascending pharyngeal artery, and its venæ comites.
3. Jugular foramen. This occupies the petro-occipital suture, and is formed by the
basi- and ex-occipital in conjunction with the petrosal. It transmits the glosso-pharyngeal,
pneumogastric, and spinal accessory nerves, a meningeal branch of the ascending pharyn-
geal artery, and receives the lateral and inferior petrosal sinuses.
4. Auditory. This marks the point of confluence of the groups of centres termed pro-
otic and opisthotic. It transmits the facial and auditory nerves with the auditory twig of
the basilar artery.
5. Trigeminal. This is only a foramen when the dura mater is present in the skull.
It is a notch at the apex of the petrosal converted into a foramen by the tentorium. The
main trunk of the trigeminal nerve with the small motor root traverses it to enter the
Meckelian cave.
6. Petro-sphenoidal. This is a notch between the side of the dorsum ephippii and
apex of the petrosal which becomes converted into a foramen by dura mater. Sometimes
this ossifies, as in fig. 96.
7. Optic. This foramen is formed by the confluence of the orbito- and pre-sphenoidal
It opens into the orbit and transmits the optic nerve and ophthalmic artery.
The Secondary Nerve-foramina
Foramina transmitting the various subdivisions of the fifth nerve. The primary foramen
of exit for the trigeminal nerve is formed partly of bone and partly of membrane at the
apex of the petrosal. The three divisions of the nerve issue through secondary foramina.
(a) The sphenoidal fissure is an elongated chink, bounded above by the orbital wing and
below by the greater wing of the sphenoid, internally by the body of the sphenoid, and
externally by the frontal. It opens into the orbit, and transmits the third, fourth, first
(ophthalmic) division of the fifth, and sixth nerves, also the ophthalmic vein.
(b) The foramen rotundum is the only exception to the rule relating to the formation of
nerve-foramina: it is probably a segment of the sphenoidal fissure. The foramen is
really a canal running from the middle cranial fossa to the spheno-maxillary fossa, and
transmits the second or maxillary division of the trigeminal.
(c) Foramen ovale. This at birth is a gap in the hinder border of the greater wing
(ali-sphenoid) of the sphenoid, and is converted into a foramen by the petrosal; sub-
sequently it becomes complete in the sphenoid. It transmits the third (inferior maxillary)
division of the trigeminal and the small or motor root, the small superficial petrosal nerve
(which occasionally passes through a separate foramen), and the small meningeal artery
with its venæ comites.
The ethmoidal canals. These commence in the suture between the os planum and
the frontal bone, and traverse the space between the upper surface of the lateral mass
MORPHOLOGY OF THE SKULL
105
of the ethmoid and the horizontal plate of the frontal, to emerge on the cribriform plate;
they are situated outside the dura mater. The anterior foramen transmits the nasal
branch of the ophthalmic, which subsequently gains the nasal cavity by passing through
the nasal slit (ethmoidal fissure) beside the crista galli.
The infraorbital canal indicates the line of confluence of the maxillary and malar
centres of the superior maxilla; occasionally it is completed by the malar; rarely it is
incomplete above, and communicates by a narrow fissure with the orbit. It lodges the
infraorbital nerve and artery.
The spheno-malar foramen is situated in the suture between the malar and the greater
wing of the sphenoid (ali-sphenoid): it transmits the temporal branch of the orbital nerve
and a branch of the lachrymal artery. In the adult this foramen may be wholly confined
to the malar bone.
The malar canals traverse the malar bone, and indicate the line of confluence of the
two chief centres for this bone. The malar twigs of the orbital nerve issue from them
accompanied by arterial twigs.
The spheno-palatine foramen is a deep groove between the orbital and sphenoidal
processes of the palate bone, converted into a foramen by the sphenoidal turbinal. It is
traversed by the naso-palatine nerve and artery as they enter the nasal from the spheno-
maxillary fossa.
Scarpa's foramina are two minute openings in the meso-palatine suture where it is in
relation with the anterior palatine fossa. They are traversed by the naso-palatine nerves.
The pterygo-palatine foramen is situated between the sphenoidal process of the palate
bone, the internal pterygoid plate of the sphenoid, and the sphenoidal turbinal. The
pterygo-palatine nerve and artery pass through it.
The Vidian canal is trumpet-shaped: the narrower end is situated in the sphenotic
foramen; the broader orifice opens on the posterior wall of the spheno-maxillary fossa.
The canal is 10 mm. long; in the foetal skull it is a chink between the base of the interna
pterygoid plate, the ali-sphenoid, and the lingula of the sphenoid. The canal is traversed
by the Vidian branch of the spheno-palatine ganglion and the Vidian artery.
The posterior palatine canal is a passage left between the maxilla, the vertical plate and
tuberosity of the palate bone, and the internal pterygoid plate; it commences on the hard
palate by the posterior palatine foramen. The descending palatine nerve and artery
traverse this canal. Several foramina open from it. In the suture between the vertical
plate of the palate bone and the maxilla, two small openings allow minute nerves to issue
for the middle and inferior turbinals. In the fissures between the tuberosities of the
palate and maxillæ, and the pterygoid plates, the middle and external palatine nerves issue.
These foramina are sometimes called accessory and external palatine canals.
The mandibular or inferior dental canal runs between the dentary and splenial elements
of the mandible. The posterior orifice of the canal is the mandibular (inferior dental)
foramen; the anterior orifice, the mental foramen, indicates the line of union of the
mento-Meckelian and dentary centres. The mandibular nerve and artery enter the canal
at its posterior orifice; the mental foramen allows the mental nerve to escape from the
canal accompanied by the mental artery.
Foramina transmitting the facial nerve and its branches.--The main trunk of the facial
enters the internal auditory meatus and traverses the Fallopian canal. In the early
embryo the nerve lies on the petrosal, and is not covered in with bone until the fifth
month of foetal life. The terminal orifice, the stylo-mastoid foramen, is situated between
the tympanic, tympano-hyal, and epiotic elements of the complex temporal bone.
The iter chorda posterius' is a chink between the squamosal and the tympanic
elements, and allows the chorda tympani nerve to enter the tympanum. The fissure of
exit for this nerve is the subdivision of the Glaserian fissure termed the canal of Huguier,
or 'iter chordæ anterius.' The Glaserian fissure lies between the tympanic plate and the
squamosal. It transmits the tympanic branch of the internal maxillary artery, and lodges
the slender process of the malleus.
The spheno-maxillary fissure is situated between the posterior border of the orbital plate of
the maxilla and a smooth ridge on the orbital surface of the greater wing of the sphenoid.
It transmits the superior maxillary division (second) of the fifth nerve.


106
THE SKELETON
THE RIBS AND STERNUM
The Ribs.-These form a series of narrow flattened bones, twenty-four in
number, arranged in twelve pairs, extending from the sides of the thoracic vertebræ
towards the median line on the anterior aspect of the trunk.
The first seven pairs are termed true ribs, because their anterior ends are
connected by means of cartilage with the sides of the sternum. The lower five-
false ribs are subdivided into two sets: the eighth, ninth, and tenth are con-
nected together by their costal cartilages; the eleventh and twelfth have their
anterior extremities free, and are called in consequence floating ribs. Thus the
first seven are, vertebro-sternal; the eighth, ninth, and tenth, vertebro-chondral;
the eleventh and twelfth, vertebral ribs.
The ribs increase in length from the first to the seventh, and then decrease from
this rib to the twelfth.
In breadth they increase from behind forwards; the greatest breadth of a
rib is at its junction with the costal cartilage. The two or three upper
ribs
form nearly a right angle with the spine, but the succeeding set curve obliquely
downwards. The obliquity is greatest at the ninth, and then decreases in the ribs
below.
Typical characters of a rib.-The seventh is regarded as the most typical rib.
It presents a vertebral extremity or head; a narrow portion or neck; a sternal
end; and an intermediate portion, the shaft.
The head has two facets divided by a horizontal crest. The crest is connected
by an interosseous ligament with an intervertebral disc; the facets articulate
with the demi-facets on the sides of the bodies of two vertebræ. As a rule, the
lower facet is the larger, and articulates with the thoracic vertebra, to which the rib
corresponds in number. This is the primary facet, and is the one represented in
those ribs which possess only a single facet on the rib-head. The anterior margin
is lipped for the costo-vertebral (stellate) ligament.
The neck is that portion of the rib extending from the head to the tubercle.
The posterior surface of the neck is in relation with the transverse process
of the lower vertebra with which the head articulates; it forms the anterior
boundary of the costo-transverse foramen, and is rough where it gives attach-
ment to the middle costo-vertebral ligament. The superior border of the neck
is continuous with the corresponding border of the shaft, and at the point where
the neck ends this border is produced so as to form a crest (crista colli superior)
for the anterior costo-transverse ligament. The inferior border of the neck is
continuous with the ridge of the subcostal groove. This difference in the relation
of the neck to the upper and lower borders of the rib shaft is useful in deter-
mining to which side a rib belongs.
The tubercle consists of an upper part, rough for the posterior costo-transverse
(rhomboid) ligament, and a lower faceted portion for articulation with the tip of
the transverse process. The tubercle projects below the lower edge of the rib to
form a crest (crista colli inferior), marking the beginning of the subcostal groove.
The shaft has two surfaces and two borders. It is strongly curved. At first
the curve is in the same plane as the neck, but it quickly turns forwards at a spot
on the posterior surface of the shaft known as the angle, where it gives attach-
ment to the sacro-lumbalis muscle and some of its subdivisions. The rib has also
a second or upward curve beginning at the angle. These curves are expressed by
describing the main curve as disposed around a vertical, and the second or upward
curve around a transverse axis.

THE RIBS
107
SHAFT
Serralus
When a rib, except the first and twelfth, is laid with its lower edge upon the
table, the rib-head rises and the rib touches the table at two places, viz. at the
sternal end, and in the neighbourhood of the angle.
The external surface of the rib is convex, and gives attachment to muscles.
FIG. 112.—THE SEVENTH RIB OF THE LEFT SIDE. (Seen from below.)
SUBCOSTAL GROOVE
lies.
Model & Costo,
träume
TUBERCLE
ARTICULAR
PORTION OF
TUBERCLE
-NECK
antern Custe Wave
HEAD
Жадите
STERNAL END FOR COSTAL CARTILAGE
Costop
veletral.
ligi
Near its anterior extremity it forms a somewhat abrupt curve, indicated by a ridge
on the bone, which gives attachment to the serratus magnus muscle, and is some-
times called the anterior angle.
The internal surface is concave and presents the subcostal groove near its

108
THE SKELETON
inferior border. The groove is best marked near the angle, and lodges the
intercostal vessels and nerves. The ridge limiting the groove above is continuous
with the inferior border of the neck of the rib; it gives attachment to the internal
intercostal muscles.
The superior border is rounded, and affords attachment to the internal and
external intercostal muscles. The inferior border commences abruptly near the
angle, and gives attachment to the external intercostal muscles.
The sternal end of the shaft is cupped for the reception of the costal cartilage.
The seventh rib and its costal cartilage give attachment to the following
muscles:-
Internal intercostals (sixth and seventh).
External intercostals (sixth and seventh).
Levatores costarum (sixth and seventh).
Infracostal (when present).
Diaphragm.
Transversalis.
External oblique abdominis.
Rectus abdominis (costal cartilage).
Triangularis sterni (costal cartilage).
Pectoralis major (costal cartilage).
Serratus magnus.
Ilio-costalis, or sacro-lumbalis.
Musculus accessorius.
Longissimus dorsi.
It gives attachment to the following ligaments:-
Anterior costo-vertebral (stellate).
Middle costo-vertebral (interosseous).
Anterior costo-transverse.
Posterior costo-transverse (rhomboid).
Interosseous of rib-head.
Blood-supply. The ribs are very vascular and derive numerous branches from
the intercostal arteries. The branches in the shaft run towards the rib-head. Those
of the head and neck take a contrary direction, and run, as a rule, towards the shaft.
In the neighbourhood of the tuberosity the vessels seem to run in any direction.
Peculiar ribs.-Several of the ribs differ in many particulars from this general
description. They are the first, second, tenth, eleventh, and twelfth.
The first rib is the broadest and most sharply curved. The head is small,
and, as a rule, is furnished with the only one articular facet. The tubercle is
large and prominent, the neck narrow. The shaft is broad, has no angle, and
is curved around a vertical axis only. The anterior surface presents two shallow
grooves separated near the superior border by a rough surface (Lisfranc's
tubercle) for the scalenus anticus muscle. The groove in front of this surface
is for the subclavian vein,
the groove behind it is for the subclavian artery.
Between the groove for the artery and the tubercle there is a rough surface for the
scalenus medius muscle; anterior to this rough surface and close beside the groove
is an area from which the first digitation of the serratus magnus takes origin.
The under surface is smooth and lacks a groove. The inferior border is thick,
and rounded for the internal and external intercostal muscles.
The costal cartilage of this rib fuses with the manubrium of the sternum;
occasionally the sternal extremity and costal cartilage of this rib are replaced by
fibrous tissue. When a well-developed cervical rib is present, the head of the first
may present two facets as in a typical rib.
The first rib, with its costal cartilage, gives attachment to the following
muscles:-
Internal intercostal.
External intercostal.
Levator costæ.
Scalenus anticus.
Scalenus medius.
Subclavius (costal cartilage).
Sterno-hyoid (costal cartilage).
Pectoralis major (costal cartilage).
Serratus magnus.
Musculus accessorius.

THE RIBS
109
Levator costæ and
accessorius
Scalenus medius
TUBERCLE
NECK
HEAD
FIG. 113.-FIRST AND SECOND RIBS.
External
Intercostals
GROOVE FOR SUBCLAVIAN
ARTERY
Scalenus anticus
Serratus
magnus
GROOVE FOR SUBCLAVIAN
VEIN
SHAFT-
Levator costæ
Accessorius
(insertion)
Cervicalis ascendens
(origin)
Serratus posticus
superior
(insertion)
Scalenus posticus
Third digitation of
serratus magnus
External
intercostals
FIG. 114.-THE VERTEBRAL ENDS OF TENTH, ELEVENTH, AND TWELFTH RIBS.
ANGLE
X
XI
XII
INGLE FACET. (SOME-
TIMES TWO FACETS ARE
PRESENT)
SINGLE FACET. (THIS
RIB HAS AN ANGLE,
BUT NO TUBEROSITY
AND NO NECK)
SINGLE FCAET. (THIS
RIB HAS NEITHER
TUBEROSITY, ANGLE,
NOR NECK)

110
THE SKELETON
Blood-supply.-This is derived mainly from the superior intercostal branch of
the subclavian artery.
The second rib, like the first, is strongly curved; its posterior angle is faintly
marked; and the shaft, like that of the first, can lie flat on the table. It has a
prominent anterior angle for the serratus magnus.
It gives attachment to the following muscles :-
Internal intercostals (first and second).
External intercostals (first and second).
Levator costæ.
Pectoralis major (costal cartilage).
Serratus magnus.
Serratus posticus superior.
Scalenus posticus.
Musculus accessorius.
Blood-supply. Superior intercostal branch of the subclavian artery, and the
first aortic intercostal.
The tenth rib has usually a single facet on its head. Occasionally a second is
present. When this is the case, the ninth thoracic vertebra is not exceptional, and
presents two demi-facets.
The eleventh rib has a single facet on the head. The angle is feebly marked,
and the subcostal groove shallow. It lacks a neck and tubercle.
The twelfth rib has a large head furnished with one facet. The shaft is
narrow, and its length extremely variable. It may be as short as 3 cm., or attain
a length of 20 cm. (8").
The twelfth rib gives attachment to the following muscles :-
Internal intercostal.
External intercostal.
Internal oblique.
Serratus posticus inferior.
Musculus accessorius.
Levator costæ.
Diaphragm.
Transversalis abdominis.
Sacro-lumbalis or ilio-costalis.
Erector spinæ.
External oblique.
Quadratus lumborum.
Latissimus dorsi.
The costal cartilages are bars of hyaline cartilage attached to the anterior
extremities of the ribs; they represent unossified epiphyses. Like the shaft of
a rib, each has an outer and inner surface; the outer surfaces give origin and
insertion to large muscles; and the inner surfaces, from the second to the seventh
inclusive, are in relation with the triangularis sterni. The upper and lower borders
serve for the attachment of the internal intercostal muscles. The upper seven
cartilages, and occasionally the eighth, are connected with the sternum. The first
fuses with the manubrium; the remaining six are received in small articular
concavities, and retained by means of ligaments. The cartilages of the vertebro-
chondral ribs are united to each other and to the seventh costal cartilage by
ligaments (sometimes by short vertical bars of cartilage), and those of the vertebral
ribs end freely. The inner surfaces of the lower six afford attachment to the
diaphragm and the transversalis muscle.
The second, third, fourth, and fifth costal cartilages articulate with the sides of
the sternum, at a spot corresponding to the junction of two sternebræ. The sixth
and seventh (and eighth when this reaches the sternum) are arranged irregularly.
As a rule the sixth lies in a recess in the side of the fifth sternebra; the seventh
corresponds to the line of junction of the meso- and metasternum; and the eighth
articulates with the metasternum. (See fig. 116.)
Blood-supply. The twigs for the costal cartilages are derived from the terminal
twigs of the aortic intercostals, and from the internal mammary arteries.
Development. At the eighth week of intra-uterine life the ribs are cartila-
ginous. About this date an earthy spot appears near the angle of each rib, and

THE RIBS
111
spreads with great rapidity along the shaft, and by the fourth month reaches as
far as the costal cartilage; the proportion borne by the rib-shaft to the costal
cartilage is about the same at this date as in adult life. Whilst the ribs are in a
cartilaginous condition, eight of them reach the sternum; even after ossification
has taken place, the costal cartilage of the eighth rib, in many instances, articulates
with the sternum as late as the eighth month (fig. 116). This relationship may
FIG. 115.-RIB AT PUBERTY.

EPIPHYSIS FOR THE HEAD. APPEARS AT
FIFTEEN; FUSES AT TWENTY-THREE
EPIPHYSIS FOR TUBERCLE. APPEARS AT
FIFTEEN; FUSES AT TWENTY-THREE
THE CARTILAGINOUS SHAFT COMMENCES TO OSSIFY
AT THE EIGHTH WEEK OF INTRA-UTERINE LIFE
persist through life, but usually the cartilage retrogresses, and is replaced by
ligamentous tissue. About the fifteenth year a secondary centre appears for the
head of each rib, and a little later one makes its appearance for the tubercle,
except in the tenth, eleventh, and twelfth ribs. The secondary centres fuse with
the ribs about the twenty-third year. The costal cartilage stands in relation to
the rib-shafts as unossified epiphyses; the rib-shaft increases in length mainly at
its line of junction with the costal cartilage.
Variations in the Number and Shape of the Ribs
The ribs may be increased in number by addition either at the cervical or lumbar end
of the series, but it is extremely rare to find an additional rib or pair of ribs in both the
cervical and lumbar region in the same subject.
Cervical ribs are fairly common; as a rule they are of small size and rarely extend
more than a few millimetres beyond the extremity of the transverse process. Occasion-
ally they exceed such insignificant proportions and reach as far as the sternum: between
these two extremes many varieties occur. As a rule, the existence of a cervical rib is not
detected until the skeleton is macerated; hence we know little of the correlated arrange-
ment of soft parts. In one fortunate case Turner was able to make a thorough dissection

112
THE SKELETON
of a specimen in which a complete cervical rib existed. Its head articulated with the
body of the seventh cervical vertebra and had a stellate ligament. The tubercle was well
developed, and articulated with the transverse process. The costal cartilage blended with
that of the first thoracic rib, and gave attachment to the costo-clavicular ligament.
Between it and the first thoracic rib there was a well-marked intercostal space occupied
by intercostal muscles. It received the attachment of the scalenus anticus and medius
muscles, and it was crossed by the subclavian artery and vein. The nerves of the inter-
costal space were supplied in part by the eighth cervical and first dorsal. The artery of the
space was derived from the deep cervical, which, with the superior intercostal, arose from
the root of the vertebral. The head of the first thoracic rib in this specimen articulated with
the seventh cervical, as well as with the first thoracic vertebræ. An interesting fact is
also recorded in the careful account of this specimen :-There was no movable twelfth
thoracic rib on the same side as this well-developed cervical rib, and the twelfth thoracic
vertebra had mammillary and accessory processes, and a strong elongated costal process,
and was in linear series with the lumbar transverse processes.
Gruber and Turner from a careful and elaborate study of this question summarise the
variations in the cervical rib thus:-It may be very short and possess only a head, neck, and
tubercle. When it extends beyond the transverse process, its shaft may end freely or join
the first thoracic rib: this union may be effected either by bone, cartilage, or ligament.
In very rare instances it may have a costal cartilage and join the manubrium of the
sternum. Not infrequently a process, or eminence, exists on the first thoracic rib at the
spot when it articulates with a cervical rib.
FIG. 116.-THE THORAX AT THE EIGHTH MONTH.
(On the left side eight cartilages reach the sternum.)
Lumbar ribs are of less significance than cervical ribs and rarely attain a great length.
Their presence is easily accounted for, as they are the differentiated costal elements of the
transverse processes. They are never so complete as in cervical ribs, and articulate only
with the transverse processes; the head never reaches as far as the body of the vertebra,
and there is no neck or tubercle. An extra levator costa muscle is associated with a
lumbar rib.
Not the least interesting variation of a rib is that known as the bicipital rib. This
condition is seen exclusively in connection with the first thoracic rib. The vertebral end
consists of two limbs which lie in different transverse planes. These bicipital ribs have been
especially studied in whales and man. This abnormality is due to the fusion of two ribs,
either of a cervical rib with the shaft of the first thoracic; or the more common form,
the fusion of the first and second true ribs.
Among unusual variations of ribs should be mentioned the replacement of the costal
cartilage and a portion of the rib shaft by fibrous tissue, a process which occurs as a normal
event, during development, in the eighth rib.
Sometimes the shafts of two or more ribs may become united by small quadrilateral
plates of bone extending across the intercostal spaces.
The sternum is a thin flat bone situated in the anterior wall of the thorax. In
the young subject it consists of six pieces, or sternebræ. Of these, the four middle
fuse together to form the gladiolus (mesosternum); the superior remains distinct

THE STERNUM
113
throughout life as the manubrium (pre-sternum); and the lower segment, also
distinct until very advanced life, is the xiphoid (metasternum). The anterior
surface of the adult sternum is convex, and gives origin to the pectoralis major
muscle of each side; near its superior angle the sterno-mastoid muscle arises.
This surface is traversed by five lines, indicating the former segmentation of this
bone. The posterior surface is concave, and traversed by five lines correspond-
ing to those on the anterior surface. At the upper part it gives origin to the
sterno-hyoid and sterno-thyroid muscles. The posterior surface of the lower four
segments gives origin to the triangularis sterni. The xiphoid is usually perforated;
a branch of each internal mammary artery traverses the foramen; and on each
side of it a portion of the diaphragm is attached. Occasionally the xiphoid is bifid.
The superior border presents the interclavicular notch, to which the fibres of the
interclavicular ligament are attached; this border terminates at each end in an
articular notch for the sternal end of the clavicle. The margins of the notch give
attachment to the sterno-clavicular ligaments. The lateral borders of the sternum
present a series of depressions, which receive the sternal extremities of the costal
cartilages of the first seven ribs, and occasionally that of the eighth (see fig. 116).
The borders intervening between these depressions or notches are in relation with
the internal intercostal muscles.
In order to appreciate the nature of these notches, it is advantageous to study
the sternum in a young subject. Each typical sternebra presents four angles; each
angle presents a demi-facet. Between each sternebra there is an inter-sternebral
disc; when two sternebræ are in position, each notch for a costal cartilage is formed.
by a sternebra above and below with an intersternebral disc in the middle, thus
repeating the relation of the rib-head to the vertebral centra. Later in life these
fuse more or less together, except in the case of the first and second sternebræ,
which usually remain separate to the end of life. The first (pre-sternum) is the
most modified of all the sternebræ, and differs from them in the fact that the costal
cartilage of the first rib is continuous with it, and in the fact that it supports the
clavicles., Occasionally a rounded pisiform bone is seen on each side, immediately
internal to the articular notch for the clavicle; these are the episternal bones.
The last sternebra, or xiphoid, is the least developed and, though calcified in old
age, rarely ossifies. Its tip is directly continuous with the linea alba, and the
base gives slight attachment to the rectus abdominis muscle.
The following muscles are attached to the sternum :-

Pectoralis major.
Sterno-cleido mastoid.
Internal intercostals.
Rectus abdominis.
Triangularis sterni.
Transversalis.
Diaphragm.
Sterno-hyoid.
Sterno-thyroid.
Ligaments. In addition to the ligaments proper to the costal cartilages, the
following require enumeration :-
Interclavicular.
Anterior sterno-clavicular.
Posterior sterno-clavicular.
Interarticular fibro-cartilage.
Linea alba.
Blood-supply. The arteries of the sternum are derived mainly from the
internal mammary arteries by direct branches termed sternal: many twigs are
furnished by the perforating branches of the internal mammary, and also from the
terminal twigs of the aortic intercostals.
Development. The sternum results from the fusion of the ventral ends of the
cartilaginous bars which in the early embryo represent the ribs. At first these
bars fuse together laterally, and for some time the sternum is represented by two
I

114
THE SKELETON
strips of cartilage separated by a median fissure. Very early this gap is bridged
over anteriorly. Nine costal cartilages are in relation with the sternum at this
stage. Gradually the lateral strips unite with each other to form the meso-
sternum. The ninth costal cartilage divides: one part remains attached to the
FIG. 117. THE STERNUM. (Anterior view.)
INTERCLAVICULAR NOTCH
CLAVICULAR NOTCH
FOR FIRST COSTAL CARTILAGE
SECOND-
THIRD-
FOURTH
FIFTH
SIXTH
SEVENTH
XIPHOID FORAMEN-
-Sterno-mastoid
MANUBRIUM
OR
PRE-STERNUM
-Pectoralis major
ir
GLADIOLUS
OR
MESOSTERNUM
IV
Rectus abdominis
VI
Aponeurosis of
transversalis and
external oblique
XIPHOID
OR
METASTERNUM
bool
sternum and becomes the xiphoid, whilst the end still attached to the rib acquires
a new attachment to the eighth cartilage. The ends, still adherent to the sternum,
may remain separate and give rise to a bifid metasternum (xiphoid); much more

THE STERNUM
115
frequently they unite, leaving a small foramen. The eighth cartilage may retain
its sternal attachment permanently.
At first the sternum and costal cartilages are continuous; a joint soon forms
between the pre-sternum and metasternum. Gradually joints arise between
FIG. 118.-THE STERNUM. (Posterior view.)
CLAVICULAR NOTCH
Sterno-hyoid
Sterno-thyroid
SECOND
THIRD
FOURTH
Triangularis sterni.
- FIFTH
SIXTH
SEVENTH
FOR FIRST COSTAL CARTILAGE
Diaphragm
the costal cartilages and the sternum (except in the case of the first). The division
of the metasternum into sternebræ is a still later process, and arises during the
process of ossification.
I 2

116
THE SKELETON
Ossification.-The transformation of the sternum into bone is a slow and
irregular process. The pre-sternum (manubrium) has a mesial nucleus about the
sixth month of intra-uterine life; later, several smaller accessory centres may
appear. The mesosternum usually ossifies from seven centres. The second
sternebra ossifies from a single median nucleus about the eighth month. Below
this, three pairs of ossific nuclei appear, and they may remain long separate. Of
these, two pairs for the third and fourth sternebræ are visible at birth. The pair
for the fifth sternebra make their appearance towards the end of the first year. The
various lateral centres unite in pairs, and at the sixth year the sternum consists of
six sternebræ, the lowest (metasternum) being cartilaginous. Gradually the four
pieces representing the mesosternum fuse with each other, and at twenty-five they
form a single piece, but exhibit, even in advanced life, traces of their original
separation.
FIG. 119. Two STAGES IN THE FORMATION OF THE CARTILAGINOUS STERNUM.
VI
VII
VEI
I
II
III
IV
A
CLAVICLE
(After Ruge.)
B
II
III
IV
V
VI
VII
VIII
IX
X
IX
The metasternum is always imperfectly ossified, and does not ankylose with the
mesosternum till after middle life. The pre-sternum and mesosternum rarely
fuse. The dates given above for the various nuclei are merely approximations, for
they are extremely variable, not only in appearing, but in their number. The same
remark applies also to the age at which the various segments ankylose; hence the
sternum affords very uncertain data as to age.
Abnormalities of the Sternum.-The mode of development of the sternum as
described above is of importance in connection with some deviations to which it is
occasionally subject. At an early period it consists of two lateral halves; in some
rare instances these have failed to unite, and thus give rise to the anomaly
of a completely cleft sternum. The union of the two halves may occur in the region
of the manubrium, but fail below this point; in some instances the upper and
lower segments have duly coalesced with the opposite side, but union has failed in
the middle segments. The clefts resulting from these failures of coalescence are in
many instances so small as not to be of any moment, and not even recognised
until the skeleton has been prepared. In a few individuals they have been so
extensive as to allow the pulsation of the heart to be perceptible to the hand, and
even to the eye, through the skin covering the defect in the bone.
A common variation in the sternum is asymmetry of the costal cartilages.
Instead of corresponding, the cartilages may articulate with the sternum in an
alternating manner. The cause of this asymmetry is not very obvious.

THE THORAX
117
THE THORAX
The thorax is a bony basket of conical shape, formed by the thoracic vertebræ,
the ribs with their costal cartilages, and the sternum. The thorax is compressed
antero-posteriorly so that it measures less in the sagittal than in the transverse axis:
it is also deeper posteriorly than anteriorly. Its posterior boundaries are formed
by the thoracic vertebræ and the ribs as far outward as their angles; the backward
FIG. 120. THE THORAX. (Front view.)

curve of the ribs produces on each side of the vertebræ a deep furrow, the costo-
vertebral groove, in which the erector spine muscle and its subdivisions are lodged.
The anterior boundary is formed by the sternum and costal cartilages. This
surface is slightly convex, and has a slight inclination forwards in its lower part.
The lateral boundaries are formed by the ribs from their angles to the costal
cartilages.
The top of the thorax presents an elliptical aperture, the thoracic inlet, which
measures, on an average, 12.5 cm. (5") transversely, and 6.2 cm. (2") in its sagittal
axis.
The lower opening of the thorax is very irregular, and forms two curved
lines ascending upwards from the last rib to the lower border of the gladiolus
(mesosternum). These two borders form the sub-costal angle, and the xiphoid
(metasternum) projects into the middle of it. The intervals between the ribs
are the intercostal spaces, and are eleven in number on each side.

118
THE SKELETON
THE CLAVICLE
The clavicle is a rod of bone passing from the top of the sternum to the acromion
process of the scapula. It presents two curves: an inner, with the convexity directed
forwards; and an outer, the smaller, with the convexity directed backwards. The
FIG. 121. THE LEFT CLAVICLE. (Superior surface.)
OUTER OR
ACROMIAL
END
Trapezius
Deltoid
ANTERIOR
POSTERIOR
Pectoralis major
Sterno-mastoid
INNER OR
STERNAL
END
clavicle consists, for descriptive purposes, of an outer flattened, and an inner
prismatic portion.
The outer third has two surfaces and two borders. The superior surface looks
directly upwards, and affords attachment to the trapezius muscle posteriorly, and
FIG. 122.-THE LEFT CLAVICLE. (Inferior surface.)
POSTERIOR
Oblique
line for
Capsular
ligament
trapezoid
ligament
Tuberosity for
conoid ligament Subclavius
ACROMIAL FACET
Deltoid
Rhomboid
ligament and
Sterno-
hyoid Sterno-thyroid
Pectoralis major
ANTERIOR
FACET FOR FIRST
COSTAL CARTILAGE
STERNAL FACET
the deltoid anteriorly; a small tract intervening between the muscles is subcutaneous.
The inferior surface is rough, and at its most posterior part presents the tuberosity
of the clavicle; it overhangs the coracoid process and gives attachment to the
conoid ligament. From the tuberosity a ridge, the oblique line, runs outwards and
forwards; to it the trapezoid ligament is attached. The anterior border is thin;
presents often a small prominence, the deltoid tubercle, and gives origin to the
deltoid muscle. The posterior border is thick and rounded; to it the trapezius is
inserted.
The inner two-thirds is prismatic in form; it has three surfaces and three
borders. Of these, the anterior surface is convex and presents near the sternal
end a rough surface for the sternal portion of the pectoralis major, and a rough
surface above for the sterno-cleido-mastoid. Near the middle of the shaft it is
smooth and covered by the thin platysma myoides; sometimes a small canal passes

THE CLAVICLE
119
at right angles through this surface of the clavicle; it is traversed by a clavicular
branch of the cervical plexus. The posterior surface is concave, and forms an
arch over the brachial plexus and subclavian artery. The inferior surface com-
mences externally as a groove for the subclavius, the floor of the groove being
continuous with the inferior surface of the outer third of the clavicle, and frequently
presents the orifice of the nutrient foramen. Internally, this groove becomes
very narrow, and runs on to the rough surface for the rhomboid ligament. On the
sternal side of the rhomboid impression there is often a facet where the clavicle
plays on the first costal cartilage. Close beside this facet the sterno-hyoid finds
an attachment, and occasionally the sterno-thyroid. Of the three borders, the
superior separates the anterior and posterior surfaces; it is faintly marked towards
the sternal end; externally, it becomes continuous with the posterior border of
the outer third. The anterior border separates the anterior and inferior surfaces:
it is continuous with the anterior border of the flattened portion. The posterior
border separates the inferior and posterior surfaces, and forms the posterior lip
of the groove for the subclavius; it begins at the conoid tubercle, and ends at
the rhomboid depression. The inner or sternal end of the clavicle is broad and
expanded; it plays upon a fibro-cartilage interposed between it and the clavicular
facet of the manubrium of the sternum, and its borders are rough for the attach-
ment of the sterno-clavicular and interclavicular ligaments. The acromial, or outer
end, presents a smooth articular facet, directed slightly downwards for the acromion;
its edges, especially the superior, are rough for the acromio-clavicular ligaments.
The following muscles are attached to the clavicle:--
Sterno-cleido-mastoid.
Pectoralis major.
Platysma myoides.
Subclavius.
Ligaments:-
Interclavicular.
Interarticular (sternal).
Capsular (sterno-clavicular).
Rhomboid or costo-clavicular.
Capsular (acromio-clavicular).
Deltoid.
Trapezius.
Sterno-hyoid.
Sterno-thyroid (occasionally).

Interarticular (acromio-clavicular).
Conoid.
Trapezoid.
Costo-coracoid membrane.
Deep cervical fascia.
Blood-supply. The nutrient artery is a branch of the suprascapular; it enters
the bone on the under surface of the shaft near the middle of the subclavian groove.
It is directed towards the acromial end. The acromial end of the clavicle receives
numerous branches from the acromio-thoracic artery, and twigs from the arteries
in the muscles attached to it.
Ossification. The clavicle is ossified from two centres. The primary nucleus
appears in the sixth week of embryonic life in the tissue immediately overlying the
cartilaginous pre-coracoid bar (see p. 124). The clavicle begins as a membrane
bone, but the ossification quickly extends into the underlying cartilage; it is
therefore a dermal splint engrafted on cartilage. About the seventeenth year a
secondary nucleus appears at the sternal end. Consolidation is complete by the
twentieth year.

120
THE SKELETON
THE SCAPULA
The scapula is a large flat bone, triangular in shape, situated on the posterior
aspect of the thorax, and resting on the ribs from the second to the seventh. Of
its two surfaces the anterior is deeply concave, forming the subscapular fossa, which
FIG. 123. THE LEFT SCAPULA. (Dorsal surface.)
Biceps
ACROMION
PROCESS
Deltoia
Coraco-acromial
ligament
NECK OF SCAPULA
AND SCAPULAR
NOTCH
Capsular lig.
GLENOID FOSSA
GROOVE FOR DORSAL ARTERY.
OF THE SCAPULA
Pectoralis
minor
Omo-hyoid and the transverse ligament
SUPERIOR ANGLE
CORACOID
Trapezius
SUPRASPINOUS
FOSSA
Levator
anguli
scapulæ
Supra-
spinatus
SPINE
INFRASPINOUS
FOSSA
Rhomboideus
minor
Teres minor.
Infraspinatus
Rhomboideus
major
AXILLARY BORDER-
Teres major-
Latissimus dorsi
-VERTEBRAL
BORDER
INFERIOR ANGLE
is marked by several ridges commencing at the posterior border of the bone and
passing transversely; these ridges divide this surface into several shallow grooves
from which the subscapular muscle takes origin: the highest groove is the deepest.
The outer third of this surface is smooth, and overlapped by the subscapular muscle:
the superior and inferior angles are somewhat triangular, and connected by a narrow
ridge of bone along the posterior border. This ridge and its terminal surfaces
serve for the insertion of the serratus magnus.
The posterior surface, or dorsum, is generally convex; it is unequally divided

THE SCAPULA
121
by a prominent lip of bone, the spine. The part above the spine is the supra-
spinous fossa, and lodges the supra-spinatus muscle. The hollow below the spine is
the infraspinous fossa; it is larger than the supraspinous fossa, and is limited
inferiorly by a ridge which runs from the glenoid fossa backwards to join the
posterior border a short distance above the inferior angle. To this oblique ridge
the stout aponeurosis is attached which separates the teres major and teres minor
muscles from the infra-spinatus muscle. The infra-spinatus arises from the inner
two-thirds of the infraspinous fossa, and overlaps the outer third. The supra-
and infra-spinous fossæ communicate with each other round the outer end of the
Serratus magnus
FIG. 124. THE LEFT SCAPULA. (Ventral surface.)
SUPRASCAPULAR NOTCH Conoid lig. Trapezoid ligament
Coraco-acromial
ligament
Biceps and coraco-
brachialis
CLAVICULAR FACET
Biceps
GLENOID FOSSA
NECK
Capsule
SUBSCAPULAR
FOSSA
Subscapularis
Triceps (middle
or long head)
Serratus magnus
spine; this part corresponds to the neck of the scapula, and the groove is the
scapular notch: it transmits the suprascapular nerve and artery from one fossa to
the other. The surface of bone below the oblique ridge presents two, and occasion-
ally three, facets for muscles: the long narrow outer one is for the origin of the
teres minor; this is crossed near its middle by a groove for the dorsal artery of
the scapula. The second facet is broader, and gives attachment to the teres major
muscle. In bones from a muscular subject the third facet, quite at the inferior
angle, is for a few fibres of the latissimus dorsi.

122
THE SKELETON
The spine commences at the posterior border of the scapula by a broad
triangular surface; it then crosses the dorsal surface obliquely to the glenoid fossa,
becoming more prominent as it passes outwards till it reaches the neck of the
scapula; from this point it forms the overhanging acromion process. The spine
presents a superior surface which gives origin to the supra-spinatus muscle, and
an inferior surface which affords origin to the infra-spinatus muscle. It has a
prominent crest, which is continuous posteriorly with the vertebral border, and,
at its commencement, is smooth for a bursa between it and the trapezius. The
crest is subcutaneous, and presents two lips-a superior for the insertion of the
trapezius, and an inferior lip for the origin of the deltoid. The crest is continued
into the acromion process.
The acromion process forms the summit of the shoulder, and presents two
surfaces, two borders, and a tip. The upper surface affords origin at its posterior
part to a portion of the deltoid. The under surface is concave and smooth. Its
inner border, a continuation of the superior lip of the crest, receives the trapezius,
and presents near the tip a small articular facet for the outer end of the clavicle;
the edges of the facet are rough for the acromio-clavicular ligaments. The outer
border is continuous with the inferior lip of the crest, with which it forms an
angle; it gives origin to the deltoid. The tip of the acromion affords attachment
to the coraco-acromial ligament.
Of the three borders presented by the scapula, the external, or axillary, is the
thickest, and extends from the posterior inferior angle to the lower margin of the
glenoid cavity. Near its junction with the glenoid cavity there is a rough surface,
from which the long head of the triceps arises; below this is the groove for the dorsal
artery of the scapula. The subscapularis muscle encroaches on this border from
the anterior surface, and the teretes from the posterior aspect. The posterior, or
vertebral, border, sometimes called the base, is the longest; it extends from the
posterior superior to the posterior inferior angle. It is very narrow, but affords
attachment to three muscles: namely, the levator anguli scapula above the spine;
the rhomboideus minor on a level with the spine; and the rhomboideus major,
through the intervention of a fibrous arch from the spine to the inferior angle.
The superior border is the shortest and thinnest, ending externally in the cora-
coid process. At the base of the coracoid is the suprascapular notch, to the
edges of which the transverse ligament is attached. Not infrequently the notch
is replaced by a suprascapular foramen. This notch or foramen transmits the
suprascapular nerve, and occasionally the suprascapular artery, but as a rule
the artery passes over the ligament. From the adjacent borders of the notch
and from the ligament, the omo-hyoid takes origin. The anterior angle of the
scapula is formed by the glenoid cavity. This cavity is shallow and pyriform,
with its major axis vertical; the lower end is the broader; the upper end or
apex gives origin to the long tendon of the biceps. The margins are raised,
and afford attachment to the glenoid ligament. In the recent state, the cavity
is covered with hyaline cartilage, and forms an articular fossa for the head
of the humerus. The margin is somewhat defective where it is overarched by
the acromion. The circumference is rough for the attachment of the capsular
ligament. Beyond this is a narrow constricted portion, called the neck of the
scapula.
Projecting upwards from the neck is the coracoid process, a prominence of bone
anterior to, but parallel with, the acromion. The tip of the coracoid gives origin
to the short tendon of the biceps, the coraco-brachialis muscle, and the costo-
coracoid ligament. The superior surface affords attachment to the pectoralis minor
muscle, and to the coraco-clavicular ligaments (conoid and trapezoid).
outer border has attached to it the coraco-acromial ligament.
The

THE SCAPULA
123
Muscles. The following are attached to the scapula :-
Supra-spinatus.
Infra-spinatus.
Subscapularis.
Teres major.
Teres minor.
Omo-hyoid.
Pectoralis minor.
Serratus magnus.
Deltoid.
Ligaments:-
Conoid.
Trapezoid.
Costo-coracoid membrane.
Costo-coracoid ligament.
Capsular (acromio-clavicular).
Coraco-acromial.
Suprascapular (transverse).
Latissimus dorsi.
Trapezius.
Rhomboideus major.
Rhomboideus minor.
Levator anguli scapulæ.
Biceps.
Coraco-brachialis.
Triceps (long head).
Capsular (shoulder-joint).
Coraco-humeral.
Gleno-humeral.
Glenoid.
Rhomboid loop.
Spino-glenoid.
Inferior transverse.
Blood-supply. The scapula is supplied by the following arteries:-Twigs from
the subscapular artery and from the subscapular branch of the suprascapular enter
the bone on the anterior surface. The dorsal artery of the scapula distributes
branches in the infraspinous, whilst the suprascapular artery supplies the supra-
spinous fossa, the spine, the glenoid fossa, and sends branches into the infraspinous
fossa. The acromion is supplied by branches of the acromio-thoracic artery.
FIG. 125.-OSSIFICATION OF THE SCAPULA.
The Scapula at the third year,
showing the coracoid element. (Anterior view.)

The Scapula at birth. (Anterior view.)
Ossification. The scapula is ossified from seven centres. Two may be con-
sidered as primary, and the remainder as secondary nuclei. The centre for the body
appears in a plate of cartilage near the neck of the scapula about the eighth week
of intra-uterine life, and quickly forms a triangular plate of bone, from which the
spine appears as a slight ridge about the middle of the third month. At birth the
glenoid fossa and part of the scapular neck, the acromion, coracoid, and vertebral
border are cartilaginous. During the first year a nucleus appears for the coracoid,

124
THE SKELETON
and extends into the glenoid fossa, and along the upper border as far as the
suprascapular notch.
During the fifteenth year the coracoid is ankylosed to the scapula, and the
secondary centres appear. Two nuclei are deposited in the acromial cartilage, and
fuse to form the acromion, and join the spine at the twentieth year. This union
of the acromion and spine may be fibrous, hence the acromion is often found
separate in macerated specimens. The cartilage along the vertebral border ossifies
from two centres: one in the middle, and one at the posterior inferior angle. A
thin scale may occasionally be detected at the tip of the glenoid fossa.
Morphology. It is impossible to comprehend the significance of the scapular
nuclei without considering briefly the morphology of the shoulder (pectoral)
girdle.
In its most generalised form the shoulder girdle consists of cartilage, which is
disposed in three parts. Of these, a dorsal segment represents the scapula and a
ventral bar, reaching to the sternum, represents the coracoid. The meeting place
of the coracoid and scapula is the glenoid fossa. Anterior to the coracoid there is
a third piece, more or less parallel with the coracoid, named the pre-coracoid. The
human shoulder girdle is modified from the type form, mainly in the suppression of
the pre-coracoid and, in part, of the coracoid. The suppression is brought about by
the clavicle, which commences to ossify in the membrane overlying the pre-coracoid;
it then invades and replaces the cartilage.
The scapular end of the coracoid ossifies and becomes the coracoid process of
the scapula; the ventral end degenerates to form the costo-coracoid ligament,
which lies in the free border of the membrane of that name. The dorsal cartilage
ossifies and becomes the scapula; the large tract of cartilage on the vertebral border
of the young scapula represents the large suprascapular cartilage of batrachians.
The suprascapular notch indicates the line of union of scapular and coracoid
elements. In the embryo the notch is bridged over with cartilage, which may
ossify or become ligament.
THE HUMERUS
The humerus is the longest bone of the upper limb. Its upper extremity
presents a hemispherical surface covered with cartilage, and known as the head.
The head articulates with the glenoid cavity of the scapula, and is directed upwards,
inwards, and backwards. Below the articular surface the bone is rough and con-
stricted, constituting the anatomical neck. To the outer side of the head are two
tuberosities, separated by the bicipital groove. The greater tuberosity is the higher
and more posterior; it is marked by three facets for muscles: an upper one for the
supra-spinatus, a middle for the infra-spinatus, and an inferior for the teres minor.
The lesser tuberosity is the more prominent; it serves for the insertion of the sub-
scapularis. The furrow between the tuberosities lodges the long tendon of the
biceps, extends downwards in the axis of the humeral shaft, and, gradually
becoming shallower, ends near the junction of the upper and middle third of the
shaft. The margins of this, the bicipital groove, are called lips, and afford
attachment to muscles. The pectoralis major occupies the whole length of the
outer lip. The inner lip receives, below, the teres major, and above, the latissimus
dorsi; the tendon of the latter muscle is also attached to the floor of the groove.
Between the tuberosities, the transverse humeral ligament converts the groove
into a canal. In addition to the long tendon of the biceps and its tube of synovial

THE HUMERUS
125
membrane, the groove transmits a branch of the anterior circumflex artery. The
constriction immediately below the tuberosities is the surgical neck.
The shaft is prismatic in its upper third, but flattened below. Three borders
and three surfaces may be recognised. The anterior border commences at the
FIG. 126. THE LEFT HUMERUS. (Anterior view.)
Subscapularis
Latissimus dorsi
Teres major
Supraspinatus
BICIPITAL GROOVE
Pectoralis major
Coraco-brachialis
Deltoid
Brachialis anticus.
Supinator longus
Extensor carpi radialis longior
Pronator radii teres-
Flexor carpi radialis-
Palmaris longus
Flexor sublimis digitorum
Flexor carpi ulnaris
Extensor carpi radialis brevior
Extensor communis digitorum
Extensor minimi digiti
Extensor carpi ulnaris
Supinator brevis
greater tuberosity, as the anterior or outer lip of the bicipital groove, and, passing
downwards, skirts the radial side of the coronoid fossa, to become continuous with
the ridge separating the capitellum and trochlea. The radial or outer border
extends from the posterior border of the greater tuberosity to the radial condyle.

126
THE SKELETON
This border is not well marked in the upper part of the shaft; near the middle it is
interrupted by the musculo-spiral groove; the lower half is termed the external
condylar ridge, and affords attachment to the supinator longus and extensor carpi
radialis longior muscles, and the external intermuscular septum. The ulnar or
FIG. 127. THE LEFT HUMERUS. (Posterior view.)
Capsular ligament
Infraspinatus-
Teres minor-
Triceps (external head)-
MUSCULO-SPIRAL GROOVE-
Triceps (internal head)-
Capsular ligament-
OLECRANON FOSSA-
EXTERNAL CONDYLE-
Anconeus and external lateral ligament
-INTERNAL CONDYLE
GROOVE FOR ULNAR NERVE
Flexor carpi ulnaris
internal border commences at the lesser tuberosity, as the inner lip of the bicipital
groove, and extends downwards to the ulnar (internal) condyle. Near its centre is
a ridge for the insertion of the coraco-brachialis, and below this the foramen for
the nutrient artery.

THE HUMERUS
127
The three borders considered above bound three surfaces. The external surface
lies between the anterior and radial borders. Near its middle is a rough impression
for the insertion of the deltoid; somewhat lower is the termination of the musculo-
FIG. 128. THE LEFT HUMERUS WITH A SUPRACONDYLOID PROCESS AND SOME
IRREGULAR MUSCLE ATTACHMENTS. (Anterior view.)
HEAD
LESSER TUBEROSITY
Subscapularis
Capsular ligament
Coraco-brachialis brevis
(Rotator humeri)
BICIPITAL GROOVE
Coraco-brachialis
Third head of biceps-
Brachialis anticus
Coraco-brachialis.
SUPRACONDYLOID PROCESS
Pronator radii teres
Capsular ligament
CORONOID FOSSA
INTERNAL CONDYLE
Internal lateral ligament
TROCHLEA
GREATER TUBEROSITY
Transverse humeral ligament
Fourth head of biceps
ROUGH SURFACE FOR deltoid
-THE EXTERNAL CONDYLAR RIDGE
-RADIAL DEPRESSION
EXTERNAL CONDYLE
CAPITELLUM
spiral groove. The internal surface lies between the anterior and ulnar borders.
The lower halves of the internal and external surfaces afford origin to the brachialis
anticus muscle. The internal surface usually presents, about 5 cm (2") above the
ulnar condyle, an elongated rough surface. This is the supracondyloid ridge;

128
THE SKELETON
it is occasionally replaced by a prominent spine of bone, the supracondyloid
process (fig. 128), from which a band of fibrous tissue extends to the ulnar
condyle, forming a ring, transmitting the median nerve and the brachial artery.
The nerve is not always accompanied by the artery; in some instances of high
division of the brachial the foramen transmits the interosseous artery. The process
FIG. 129.-OSSIFICATION OF THE HUMERUS.
UNITES WITH THE SHAFT AT THE TWENTIETH
YEAR
THE UPPER EPIPHYSIS IS FORMED BY THE
UNION OF THE NUCLEUS FOR THE HEAD,
GREATER TUBEROSITY, AND THAT FOR THE
LESSER TUBEROSITY. THESE FORM A COM-
MON EPIPHYSIS BEFORE UNITING WITH THE
SHAFT
SHAFT BEGINS TO OSSIFY IN THE EIGHTH WEEK-
OF INTRA-UTERINE LIFE
NUCLEUS FOR THE INTERNAL CONDYLE APPEARS
AT FIFTH; FUSES AT THE EIGHTEENTH YEAR
NUCLEUS FOR TROCHLEA APPEARS AT THE
TENTH YEAR
NUCLEUS FOR EXTERNAL CONDYLE APPEARS AT
FOURTEENTH YEAR
NUCLEUS FOR CAPITELLUM APPEARS IN THE
THIRD YEAR
THE CENTRES FOR THE RADIAL CONDYLE,
TROCHLEA, AND CAPITELLUM UNITE TOGETHER AND FORM AN EPIPHYSIS
WHICH FUSES WITH THE SHAFT AT THE SEVENTEENTH YEAR
gives origin to the pronator radii teres, and sometimes affords insertion to a part of
the coraco-brachialis.
The posterior surface lies between the ulnar and radial borders. It is obliquely
divided by the musculo-spiral groove. The surface above the groove serves for the
origin of the external head; the part below for the internal head of the triceps.

THE HUMERUS
129
The lower extremity of the humerus is flattened, and presents from the ulnar
to the radial side the following parts:- a prominent process, the ulnar (internal)
condyle, from which the pronator radii teres arises, and to the lower part of
which the internal lateral ligament is attached. From this ligament the flexor
carpi radialis, palmaris longus, flexor sublimis digitorum, and flexor carpi ulnaris
muscles arise. Posteriorly the condyle forms with the trochlea a groove traversed
by the ulnar nerve. External to the condyle there is the inferior articular surface,
subdivided by a low ridge into the trochlea and the capitellum. The trochlea is,
in shape, like the section of a pulley wheel; the ulnar extends much lower than
the radial edge; the articular surface is sharply indicated anteriorly and posteriorly.
The trochlea fits into the greater sigmoid cavity of the ulna. Above the trochlea
on the anterior surface is the rounded coronoid fossa, which receives the coronoid
process of the ulna when the forearm is flexed. On the posterior aspect there is the
olecranon fossa, for the reception of the anterior edge of the olecranon in extension
of the forearm. These fossæ in most humeri are separated by a thin translucent
disc of bone, sometimes merely by fibrous tissue, so that in macerated bones a
perforation, the supratrochlear foramen, exists. The radial head or capitellum is
received by the depression on the summit of the radius; it is limited to the anterior
and lower surface of the humerus. Above, it terminates in a shallow fossa, which
receives the edge of the radius in flexion. The ridge between the trochlea and
the capitellum corresponds to the interval between the ulna and radius; the
shallow groove on the outer side of the ridge receives the inner margin of the
head of the radius. External to the capitellum is the external or radial condyle.
It is less prominent than the ulnar condyle, and gives attachment to the external
lateral ligament of the elbow, and to a tendon from which five extensor muscles
arise-viz. extensores carpi radialis brevior, digitorum communis, minimi digiti,
carpi ulnaris, and the supinator brevis. On the posterior aspect this condyle
extends to the edge of the trochlea, and gives origin to the anconeus.
Muscles. The humerus affords attachment for the following muscles:-

Supraspinatus.
Infraspinatus.
Teres major.
Teres minor.
Subscapularis.
Deltoid.
Pectoralis major.
Coraco-brachialis.
Latissimus dorsi.
Biceps (occasionally).
Brachialis anticus.
Triceps.
Pronator radii teres.
Flexor carpi radialis.
Palmaris longus.
Flexor sublimis digitorum.
Flexor carpi ulnaris.
Supinator longus.
Extensor carpi radialis longior.
Extensor carpi radialis brevior.
Extensor digitorum communis.
Extensor minimi digiti.
Extensor carpi ulnaris.
Supinator brevis.
Anconeus.
Ligaments. To the upper extremity of the humerus the following ligaments
are attached :-
Capsular.
Coraco-humeral.
To the lower extremity :-
Internal lateral ligament
Gleno-humeral.
Transverse humeral.
External lateral ligament of the elbow joint.
Anterior ligament
Posterior ligament
K

130
THE SKELETON
Arteries. The blood-supply of the humerus is derived from the suprascapular,
and the anterior and posterior circumflex arteries. Branches from these arteries
enter the foramina which cluster around the circumference of the head and
tuberosities. At the top of the bicipital groove there is a large nutrient foramen,
which transmits a branch from the anterior circumflex artery. The nutrient
artery of the shaft is derived from a muscular branch of the brachial; it enters
the bone near the middle of the inner border immediately below the insertion of
the coraco-brachialis, and is directed to the distal end. The lower extremity is
nourished by numerous twigs derived from the anastomotic, the superior and
inferior profunda, and the recurrent branches of the radial, ulnar, and interosseous
arteries.
Ossification.-The humerus ossifies from one primary and six secondary
nuclei. The centre for the shaft appears about the eighth week of intra-uterine
life, and extends very rapidly. At birth the bone presents two cartilaginous
extremities, which ossify in the following manner :-A nucleus for the head appears
early in the first year; it is not infrequently present at birth (Spencer). The
nucleus for the greater tuberosity appears in the third year. In the fifth year a¸
centre may be deposited for the lesser tuberosity, but this is not constant. The
three nuclei coalesce to form a disc of bone, which unites with the shaft about
the twentieth year.
The inferior extremity ossifies from four centres: the centre for the capitellum
FIG. 130.--THE HEAD OF THE HUMERUS AT THE SIXTH YEAR. (In section.)

THE CENTRE FOR THE HEAD APPEARS DURING
THE FIRST YEAR IT IS SOMETIMES PRESENT
AT BIRTH
THE CENTRE FOR THE GREATER TUBEROSITY
APPEARS IN THE THIRD YEAR
appears in the third year, and those for the inner (ulnar) condyle, the trochlea,
and external (radial) condyle at the fifth, tenth, and fourteenth year respectively.
The nuclei for the capitellum, trochlea, and radial condyle coalesce before uniting
with the shaft, which they do in the seventeenth year. The ulnar condyle joins
the shaft somewhat later.
A study of the upper end of the humeral shaft before its union with the
epiphysis is of interest in relation to what is known as the neck of the humerus.
The term neck is applied to three parts of this bone. The anatomical neck is
the constriction to which the capsular ligament is attached. This is accurately
indicated by the constriction which lies internal to the tuberosities; the upper
extremity of the humeral shaft before its union with the epiphysis terminates in
a low three-sided pyramid, the surfaces of which are separated from each other
by ridges. The inner of these three surfaces underlies the head of the bone, and
the two outer surfaces underlie the tuberosities. The axis of the inner, isolated
portion forms with the shaft an angle of 130°; it constitutes the morphological
neck of the humerus, and is of the same nature as the neck of the femur. The
surgical neck is an indefinite area below the tuberosities where the bone is liable
to fracture.


THE ULNA
131
THE ULNA
The ulna is the inner bone of the forearm: it lies parallel with, but is longer
than, the radius. The upper extremity is the thickest and strongest part of the
ulna, and is of irregular shape. The superior articular surface is called the
greater sigmoid cavity, and receives the trochlea of the humerus; it is transversely
constricted near its middle. The prominence above the constriction is termed the
olecranon, the part below the coronoid process.
The olecranon process is the highest part of the ulna; to its upper surface the
triceps is inserted, and the anterior margin of this surface affords attachment to
FIG. 131.-UPPER END OF LEFT ULNA. (Outer view.)
OLECRANON
GREATER SIGMOID FOSSA
Coronoid
Orbicular ligament
LESSER SIGMOID FOSSA
Oblique ligament
Supinator brevis
Flexor profundus digitorum
Interosseous membrane
the posterior ligament of the elbow. The anterior surface of the olecranon is
articular, and forms the upper and back part of the greater sigmoid cavity, and its
margins give attachment to ligaments. The posterior surface of this process is
triangular, and separated from the skin merely by a bursa. On the inner side
there is a tubercle for the origin of the flexor carpi ulnaris; and below this a
fasciculus of the internal lateral ligament of the elbow is inserted.
The coronoid process forms the lower lip of the greater sigmoid cavity: its
upper surface is articular and forms nearly a right angle with the olecranon
portion. The anterior edge of the coronoid process is sometimes called the apex.
The inferior aspect is rough for the insertion of the brachialis anticus muscle, and
the lower outer angle has a tubercle to which the oblique ligament is attached.
The inner edge has a smooth tubercle from which the flexor sublimis digitorum
arises; the ridge of bone immediately below this tubercle gives origin to the lesser
K 2

132
THE SKELETON
head of the pronator radii teres, and below this again the rounded accessory
bundle of the flexor longus pollicis arises.
A triangular depressed surface, posterior to the sublimis tubercle, gives origin to
the upper fibres of the flexor profundus digitorum. To the outer side of the rough
surface for the brachialis anticus is a triangular space, the base of which is
represented by the lesser sigmoid cavity, which receives the lateral articular
FIG. 132. THE LEFT ULNA AND RADIUS. (Antero-internal view.)
Capsular ligament
Internal lateral ligament
Tubercle for the
flexor sublimis digitorum
External lateral ligament
Brachialis anticus
Pronator radii teres
(lesser head)
Flexor longus pollicis
(accessory head)
GREATER SIGMOID FOSSA
HEAD OF RADIUS
NECK OF RADIUS
Lower limit of
orbicular ligament
Oblique ligament
BICIPITAL TUBERCLE
Oblique ligament
Supinator brevis
Flexor sublimis digitorum
OBLIQUE LINE
ULNA
RADIUS
Interosseous membrane<
Flexor profundus digitorum
Pronator radii teres
Flexor longus pollicis
Pronator quadratus
Pronator quadratus
Anterior radio-ulnar ligament.
Internal lateral ligament.
Supinator longus
External lateral ligament
Interarticular fibro-cartilage
Capsular ligament
surface of the head of the radius; the anterior and posterior margins of this
cavity afford attachment to the orbicular ligament. The rest of the triangle is
depressed, and gives origin to the supinator brevis.
The shaft throughout the greater part of its extent is prismatic, but tapers
towards the lower extremity, becoming thin and rounded in its lower third. It has
three borders and three surfaces.

THE ULNA
133
Of the three borders, the cuter (or interosseous) is the most marked: it com-
mences at the apex of the triangle from which the supinator brevis arises, becomes
very prominent in the middle of the bone, but is indefinite near its termination;
the interosseous membrane is attached to it. The anterior border is directly
continuous with the inner edge of the rough surface for the brachialis anticus, and
FIG. 133. THE LEFT ULNA AND RADIUS. (Postero-external view.)
Triceps
Capsular ligament
OLECRANON
Lower limit of
orbicular ligament
Biceps
Supinator brevis
SUBCUTANEOUS SURFACE
Anconeus
Extensor ossis metacarpi pollicis
Extensor primi internodii
pollicis
AN APONEUROSIS IS ATTACHED TO THIS BORDER
FROM WHICH THE flexor AND extensor carpi
ulnaris, AND flexor profundus digitorum
ARISE
Extensor secundi internodii pollicis
RADIUS
ULNA
Grooves for extensor ossis, and
extensor primi internodii pollicis
For extensor carpi radialis
longior and brevior
Extensor secundi internodii.
pollicis
Extensor indicis
Extensor minimi digiti
Extensor carpi ulnaris
Internal lateral ligament
Extensor communis digitorum Capsule Posterior radio-ulnar ligament
and extensor indicis
terminates inferiorly in front of the styloid process; throughout the greater part
of its extent it is rounded, and affords origin to the flexor profundus digitorum;
in its lower fourth it is rough and prominent for the pronator quadratus. The
posterior border extends from the tubercle, near the tip of the olecranon, to the
back part of the styloid process. The upper three-fourths gives attachment to

134
THE SKELETON
an aponeurosis, from which the flexor and extensor carpi ulnaris and the flexor
profundus digitorum muscles arise.
Of the three surfaces, the anterior lies between the anterior and interosseous
borders; it is concave for the greater part of its extent. The upper three-fourths
gives origin to the flexor profundus digitorum, the lower fourth to the pronator
quadratus; the upper limit of the surface for the pronator is sometimes indicated
by a transverse ridge. The internal surface is bounded by the anterior and posterior
borders. The upper three-fourths is occupied by the flexor profundus digitorum;
the remainder is subcutaneous. The posterior surface lies between the interosseous
and posterior borders. Its upper fourth is marked off by an oblique ridge running
from the lesser sigmoid cavity to the posterior border. The surface above the line
receives the insertion of the anconeus; from the line itself a few fibres of supinator
brevis arise. The surface below the oblique line is subdivided by a vertical ridge;
the portion lying between this ridge and the posterior border is in relation with
the extensor carpi ulnaris. Between this line and the interosseous border the
following muscles arise in order from above downwards: extensor ossis metacarpi
pollicis, the extensor secundi internodii pollicis, and the extensor indicis.
The lower extremity of the ulna is of small size and consists of two parts, a
head and styloid process, separated from each other, on the under surface, by a groove
into which an interarticular cartilage is inserted. That part of the head adjacent
to the groove is semilunar in shape and plays upon the interarticular cartilage which
excludes it from the wrist-joint. The margin of the head is also semilunar, and is
received into the sigmoid cavity of the radius. The styloid process projects from
the inner and back part of the bone, and appears as a continuation of the posterior
border. To its extremity the internal lateral ligament is attached, and its posterior
surface is grooved for the passage of the tendon of the extensor carpi ulnaris.
Muscles. The following are attached to the ulna :-
Triceps.
Anconeus.
Brachialis anticus.
Pronator quadratus.
Flexor sublimis digitorum.
Flexor profundus digitorum.
Flexor longus pollicis.
Ligaments :-
Internal lateral of elbow.
Anterior of elbow.
Posterior of elbow.
Flexor carpi ulnaris.
Extensor ossis metacarpi pollicis.
Extensor secundi internodii pollicis.
Extensor indicis.
Pronator radii teres.
Supinator brevis.
Extensor carpi ulnaris.
Interosseous membrane.
Anterior radio-ulnar.
Posterior radio-ulnar.
Orbicular.
Oblique.
Internal lateral of wrist-joint.
Interarticular fibro-cartilage.
Blood-supply. The nutrient vessel enters the shaft near the middle of the
anterior surface; it is derived from the anterior interosseous trunk, and is directed
towards the proximal end. The upper extremity receives branches from the
anterior and posterior ulnar recurrent and from the interosseous recurrent. The
lower end receives twigs from the anterior and posterior interosseous arteries.
Ossification. The ulna is ossified from three centres. The primary nucleus
appears near the middle of the shaft in the eighth week of embryonic life. At
birth the greater portion of the olecranon process is cartilaginous. During the
fourth year a nucleus appears for the distal epiphysis. The cartilaginous olecranon
is mainly ossified from the shaft, and in the course of the tenth year a scale-like
epiphysis appears at its summit. This unites during the sixteenth year. The
distal epiphysis consolidates about the eighteenth year.

THE RADIUS
135
THE RADIUS
The radius is shorter than the ulna and lies parallel with it. The upper end,
or head, is surmounted by a circular disc, of which the superior surface is depressed
for the reception of the capitellum of the humerus, especially in flexion of the
forearm. The margin of the head is also articular; it is deeper on the ulnar
aspect, where it is received by the lesser sigmoid cavity of the ulna; the rest of
FIG. 134.-ARTICULAR FACETS ON THE LOWER END OF LEFT RADIUS AND ULNA.
FOR SCAPHOID
FOR SEMILUNAR
Posterior

RADIUS
ULNA
STYLOID PROCESS OF ULNA
HEAD OF ULNA: IT ARTICULATES WITH
THE INTERARTICULAR FIBRO-CARTILAGE
OF THE WRIST JOINT
Anterior
the circumference is embraced by the orbicular ligament. Below the cartilage-
covered surface of the bone there is a constricted portion, or neck, which is in
relation by its outer side with the supinator brevis.
Beneath the neck, on the anterior aspect of the bone, there is an oval eminence,
the bicipital tuberosity, divided longitudinally into a rough posterior portion for
the biceps tendon, and a smooth anterior surface in relation with the bursa which
is situated between the tendon and the tuberosity.

FIG. 135.-POSTERIOR VIEW OF THE LOWER END OF THE RADIUS AND ULNA.
RADIUS
Insertion of supinator longus
Ext. ossis metacarpi pollicis
and
Ext. primi internodii pollicis
Extensor carpi radialis
longior and brevior
TUBERCLE FOR POSTERIOR ANNULAR
LIGAMENT
Extensor secundi internodii
pollicis
STYLOID PROCESS-
-ULNA
The broad groove on the
radius is for the tendons
of ext. communis digito-
rum and extensor indicis
Extensor minimi digiti lies
in the groove between the
radius and ulna
Extensor carpi ulnaris
STYLOID PROCESS
The radius has three borders and three surfaces. Of the three borders the
interosseous is the best marked. Commencing at the posterior edge of the bicipital
tuberosity, it extends as a sharp ridge until it approaches the distal extremity of
the bone; it then divides to become continuous with the anterior and posterior
margins of the sigmoid cavity. It affords attachment to the interosseous mem-
brane. The anterior border starts from the bicipital tuberosity, crosses obliquely

136
THE SKELETON
to the outer side of the bone, and descends to the anterior border of the styloid
process. The upper third of this border is called the oblique line, and limits the
insertion of the supinator brevis and the origin of the flexor longus pollicis, and
affords attachment to the flexor sublimis digitorum. The posterior border, com-
mencing at the back of the neck of the radius, is very indistinct at first, but becomes
more marked near the middle of the bone; it terminates at the back part of the
styloid process. The anterior surface is bounded by the anterior and interosseous
borders. The upper two-thirds is occupied by the flexor longus pollicis, and a little
FIG. 136.-OSSIFICATION OF THE RADIUS AND ULNA.
-APPEARS AT THE TENTH YEAR; FUSES AT THE
SIXTEENTH YEAR
APPEARS AT THE FIFTH YEAR; FUSES AT THE
SEVENTEENTH YEAR
RADIUS-
ULNA
APPEARS AT THE FOURTH YEAR; FUSES AT THE
EIGHTEENTH YEAR
APPEARS AT THE SECOND YEAR; FUSES AT THE
TWENTIETH YEAR
less than the lower third by the pronator quadratus. The external surface lies
between the anterior and posterior borders. The upper third affords insertion to
the supinator brevis; at its centre there is a rough, low, vertical ridge for the
pronator radii teres; below this, the bone is smooth and overlapped by the tendons
of the extensores carpi radialis longior and brevior, and crossed by the extensor ossis
metacarpi pollicis and extensor primi internodii pollicis. The posterior surface lies
between the interosseous and posterior borders. The upper third is covered by the
supinator brevis; the middle third gives origin to the extensor ossis metacarpi and
extensor primi internodii pollicis; and the lower third is covered by tendons.
The lower extremity of the radius is quadrilateral; its carpal surface is articular
and divided by a ridge into an inner quadrilateral portion, concave for articulation
with the semilunar bone; and an outer triangular portion, extending on to the

THE RADIUS
137
styloid process: this is concave to receive the superior surface of the scaphoid
bone. The inner side of the lower end presents the sigmoid cavity for the recep-
tion of the rounded margin of the head of the ulna. The anterior surface is a
raised ridge to which the anterior ligament of the wrist-joint is attached. The
outer surface is represented by the styloid process; to its base the supinator longus
is inserted, and the tip serves for the attachment of the external lateral ligament of
the wrist. It is also marked by a shallow furrow for the tendons of the extensor
ossis metacarpi and extensor primi internodii pollicis. The posterior surface is
convex, and marked by two prominent ridges separating three furrows. The posterior
annular ligament is attached to these ridges, to the styloid process, and to the inner
margin, thus forming with the bone a series of tunnels. The outermost is broad,
shallow, and frequently subdivided by a low ridge. The outer subdivision is for
the extensor carpi radialis longior, the inner for the extensor carpi radialis brevior.
The middle groove is narrow and deep for the tendon of the extensor secundi
internodii pollicis. The innermost is shallow and transmits the extensor indicis and
the extensor communis digitorum which overlies the indicis. When the radius and
ulna are articulated, an additional groove is formed for the extensor minimi digiti.
Muscles. The following muscles are attached to the radius:-
Biceps.
Supinator brevis.
Supinator longus.
Pronator radii teres.
Pronator quadratus.
Extensor ossis metacarpi pollicis.
Extensor primi internodii pollicis.
Flexor longus pollicis.
Flexor sublimis digitorum.
Ligaments:-
Oblique ligament.
Interosseous membrane.
Anterior radio-ulnar.
Posterior radio-ulnar.
Posterior annular.

External lateral of wrist.
Interarticular fibro-cartilage of wrist.
Anterior radio-carpal.
Posterior radio-carpal.
Blood-supply. The nutrient artery is derived from the anterior interosseous
trunk;
it enters the shaft near the middle of the anterior surface, and runs towards
the proximal end of the bone. The head of the bone is supplied by the radial recur-
rent and interosseous recurrent arteries. The lower end is supplied by the anterior
and posterior interosseous arteries and numerous twigs from the carpal arches.
Ossification. The radius is ossified by one primary and two secondary centres.
The shaft begins to ossify at the eighth week of embryonic life. The nucleus for
the lower end appears in the second year, whilst that for the upper end is deposited
in the fifth year. The head ankyloses with the shaft at the seventeenth year, but
consolidation is delayed at the lower end until the twentieth year.
THE HAND
The skeleton of the hand consists of three parts-the carpus, metacarpus, and
phalanges.
THE CARPUS
The carpus contains eight bones, arranged in two rows, four bones in each
row. Enumerated from the radial to the ulnar side, the bones of the proximal row
are, the scaphoid, semilunar, cuneiform, and pisiform; those of the distal row, the
trapezium, trapezoid, magnum, and unciform.

138
THE SKELETON
THE SCAPHOID
This is the largest bone of the proximal row. Its superior surface is some-
what triangular and convex for articulation with the lower end and styloid process
of the radius. Its inferior surface has two facets: a large one for the trapezium,
and a small one for the trapezoid. The dorsal surface is occupied by a long, deep
groove for ligaments. The palmar surface is rough and concave above; below,
FIG. 137. THE LEFT HAND. (Dorsal surface.)
Extensor carpi
radialis longior
Extensor carpi
radialis brevior
METACARPAL
Extensor primi
internodii pollicis
Ext. secundi
internodii-
pollicis
SEMILUNAR
Carpal
SCAPHOID
PISIFORM
CUNEIFORM
TRAPEZIUM
TRAPEZOID
MAGNUM
UNCIFORM
Exte nsor carpi
FIRST PHALANX
Extensor communis digitorum
SECOND PHALANX
Extensor communis digitorum
THIRD, UNGUAL, OR TERMINAL PHALANX
Ist.
Dorsal
2nd
3rd
4th
Interosse
Muscles
IV
II
ulnaris
it has a prominent tuberosity for the attachment of the anterior annular ligament
and the abductor pollicis muscle. The outer (radial) surface is rough for liga-
ments. The inner (ulnar) surface is occupied by two articular facets, of which the
upper one is crescentic in shape for the semilunar bone, whilst the lower is deeply
concave for the reception of the head of the magnum.
-
Articulations. With radius, trapezium, trapezoid, magnum, and semilunar.

THE CARPUS
139
THE SEMILUNAR
The semilunar has a convex superior surface for articulation with the lower
end of the radius and the fibro-cartilage of the wrist. Its inferior surface is deeply
concave for the head of the magnum. The ulnar ridge of the inferior articular
surface is faceted for the unciform. The outer (radial) surface has a narrow
semilunar facet for the scaphoid, whilst the inner (ulnar) aspect of the bone
FIG. 138. THE LEFT HAND. (Palmar surface.)
Flexor carpi
ulnaris
Abductor minimi
digiti
Flexor brevis and
opponens minimi
digiti
Flexor carpi
ulnaris
Adductor pollicis
Flexor brevis
pollicis
Abductor pollicis
Opponens pollicis
Occasional insertion into trapezium
Extensor ossis metacarpi pollicis
Flexor carpi radialis
Interosseus primus volaris
Opponens pollicis
Opponens minimi
digiti
Abductor
and flexor
brevis
minimi
digiti
3rd
2nd
1st
mar interossei Muscles
Flexor brevis and
Abductor pollicis
Flexor brevis and
Adductor pollicis
Flexor sublimis digitorum
Flexor profundus digitorum
Flexor
ongus
pollicis
presents a quadrilateral facet for the base of the cuneiform. The palmar and
dorsal surfaces are rough and non-articular. Of these, the palmar is usually the
more extensive; in the remaining carpal bones the dorsal surface is the broader.
Articulations. With the radius, scaphoid, cuneiform, magnum, and unciform.

140
THE SKELETON
THE CUNEIFORM
The cuneiform (or pyramidal bone) rests by its base on the ulnar side of the
semilunar; its apex is directed downwards and to the ulnar side, and serves for
the attachment of the internal lateral ligament of the wrist. The base presents a
FIG. 139. THE LEFT SCAPHOID.
FOR RADIUS
FOR LIGAMENT
FOR TRAPEZOID
FOR TRAPEZIUM
FOR SEMILUNAR
FOR MAGNUM
FIG. 140.-THE LEFT SEMILUNAR.
FOR CUNEIFORM
FOR UNCIFORM
FOR MAGNUM
TUBEROSITY
facet for the semilunar.
The inferior surface has a sinuous articular surface for
the unciform bone. The superior surface has a convex smooth portion, where it
plays upon the interarticular cartilage which intervenes between it and the lower
FIG. 141.-THE LEFT CUNEIFORM.
FOR SEMILUNAR
FOR PISIFORM
FOR UNCIFORM
FIG. 142. THE LEFT PISIFORM.
FOR CUNEIFORM
end of the ulna; the remainder of this surface is rough for ligaments. The
palmar surface has a conspicuous facet for the pisiform bone, and the dorsal
surface is rough for ligaments.
Articulations.-Pisiform, semilunar, and unciform.
THE PISIFORM
The pisiform resembles closely a split pea. Its dorsal aspect, corresponding to
the cut surface of the pea, articulates with the facet on the palmar surface of the
cuneiform. The rest of this bone is rough for the anterior annular ligament and
the tendon of the flexor carpi ulnaris.

THE CARPUS
141
THE TRAPEZIUM
The trapezium is the first bone of the distal row; it is very irregular in
shape. The inferior surface is saddle-shaped, and articulates with the base of
the first metacarpal bone. The superior surface has a facet for the scaphoid.
The inner (ulnar) surface has two facets; the lower and smaller is for the base
of the second metacarpal, the upper and larger for the trapezoid. The radial and
FIG. 143. THE LEFT TRAPEZIUM.

FOR SCAPHOID
FOR TRAPEZOID
THE RIDGE
GROOVE FOR FLEXOR CARPI RADIALIS
FOR FIRST METACARPAL
FOR SECOND METACARPAL
dorsal surfaces are rough for ligaments. The palmar surface presents a prominent
ridge, which has to its ulnar side a deep groove which transmits the tendon of the
flexor carpi radialis. To the ridge of the trapezium the anterior annular ligament
FIG. 144. THE LEFT TRAPEZOID.

PALMAR SURFACE-
FOR TRAPEZIUM-
FOR SECOND.
METACARPAL
is attached. The palmar surface affords attachment to the abductor, flexor ossis,
flexor brevis, and sometimes a portion of the extensor ossis metacarpi pollicis.
Articulations. With the scaphoid, trapezoid, and the first and second meta-
carpal bones.
THE TRAPEZOID
The trapezoid is also very irregular in shape, and much smaller than the
trapezium. It has a broad dorsal surface; the narrow palmar surface gives
origin to a few fibres of the inner head of the flexor brevis pollicis. The portion
FIG. 145.-THE LEFT MAGNUM.
FOR SEMILUNAR-
FOR SCAPHOID-
THE RADIAL OR
OUTER SIDE
FOR TRAPEZOID-
FOR SECOND METACARPAL-
FOR THIRD METACARPAL-
FOR SEMILUNAR
FOR UNCIFORM
THE ULNAR OR
INNER SIDE
-FOR FOURTH METACARPAL
of bone between these surfaces is constricted and mapped out into articular facets;
of these, the inferior is most conspicuous; it is saddle-shaped for the base of the
second metacarpal. The radial surface has a facet for the trapezium; the ulnar
surface is articular for the magnum; and the superior surface has a facet for the
scaphoid.
Articulations. With the trapezium, magnum, scaphoid, second metacarpal.

142
THE SKELETON
THE MAGNUM
The magnum is the largest carpal bone, and occupies the centre of the wrist.
The superior surface is globular, and sometimes called the head. It is received
into the cup formed by the semilunar and scaphoid. The articular surface of the
head extends some distance on to the dorsal aspect of the bone. The inferior
surface has three facets. The middle is the largest for the base of the third meta-
carpal. The ulnar facet is for the fourth, and the small radial facet is for the
second metacarpal. The outer (radial) surface articulates with the trapezoid, and
presents above this small facet a deep groove for an interosseous ligament. The
inner (ulnar) surface of the bone has a long articular surface for the unciform
(sometimes the lower part of this surface forms a detached facet), but is rough
near its anterior part for ligaments. The palmar surface is convex and rough,
and affords origin to the inner head of the flexor brevis pollicis. The rough dorsal
surface is broad, and has a deep concavity, which serves to make the head of the
bone more prominent, and gives rise to the appearance of a neck.
Articulations. Trapezoid, unciform, semilunar, scaphoid, and second, third,
and fourth metacarpals.
THE UNCIFORM
The unciform is the most readily recognised of all the carpals, as its palmar
surface presents a prominent hook-like process; this, the unciform process, has
its concavity directed towards the radial side, and forms part of the inner boundary
of the passage for the flexor tendons; to the apex of the process the anterior annular
ligament gains an attachment. It also affords origin to the flexor brevis minimi
and opponens minimi digiti muscles. The dorsal surface is rough for ligaments.
FIG. 146. THE LEFT UNCIFORM.
UNCIFORM PROCESS
FIFTH METACARPAL
FOURTH METACARPAL
MAGNUM
oela al biosage st
The inferior surface has two facets for the bases of fourth and fifth metacarpals.
The superior surface forms the apex of a wedge, and is smooth and rounded for
articulating with a narrow facet on the ulnar side of the semilunar. The ulnar
surface is mainly articular for the cuneiform, whilst the radial surface is faceted
for the magnum.
Articulations. With the cuneiform, semilunar, magnum, and the fourth and
fifth metacarpals.
The central is an occasional element of the carpus. It is situated on the
dorsal aspect of the carpus, between the scaphoid, magnum, and trapezoid.
This
bone is a normal element of the carpus in many mammals, even in the orang
and gibbon. It is represented in the carpus of the human embryo, but in most
individuals it undergoes suppression or coalesces with the scaphoid.
Blood-supply. The arterial twigs to the carpal bones are derived from the
anterior and posterior carpal branches of the radial and ulnar arteries. A large
branch from the anterior interosseous is also distributed to the carpus, and twigs
are furnished to it from the posterior interosseous artery.
Ossification.-At birth the carpal elements are cartilaginous, and the nucleus
for each bone appears in the following order:
THE METACARPUS
143
Magnum, first year.
Unciform, second year.
Cuneiform, third year.
Semilunar, fourth year.
Trapezium, fifth year.
year.
Scaphoid, sixth
Trapezoid, eighth year.
Pisiform, twelfth year.
THE METACARPUS
The metacarpus consists of five bones. Each metacarpal bone has a shaft, a
rounded distal end termed the head, and a square-shaped proximal extremity
named the base. The shaft is prismatic; two surfaces of the prism are lateral, and
the third dorsal. The lateral surfaces afford attachment to the interosseous muscles:
on the palmar aspect of the shaft these surfaces approach each other, and for
some distance are only separated by a prominent ridge. The dorsal surface is
smooth and covered in the recent state by the tendons of the extensor muscles of
the fingers. Near the base this surface is divided by a median ridge; as this
ridge passes to the distal end of the shaft, it divides and forms two ridges which
terminate in a prominent tubercle on each side of the head of the bone. The
smooth surface on each side of the median ridge on the dorsal aspect, near the
base, is for a dorsal interosseous muscle. The base is quadrilateral; its palmar
and dorsal surfaces are rough for ligaments; the upper end articulates with the
carpus, and its lateral aspects have facets for adjacent metacarpals. The head
has a semilunar articular surface for the base of the first phalanx, and is more
FIG. 147. THE FIRST (LEFT) METACARPAL.

RADIAL SIDE
FOR TRAPEZIUM
ULNAR SIDE
extensive on the palmar than the dorsal aspect. On its palmar surface the head
is grooved for flexor tendons, each corner of the groove being surmounted by a
tubercle. The sides of the head are compressed, and each side is occupied by a
well-marked fossa.
The several metacarpals present distinctive characters. The FIRST is the most
peculiar; it is the shortest, and its shaft resembles that of a phalanx. It has a
concave palmar surface, and the dorsal surface lacks the bifurcated ridge. The
base has a saddle-shaped articular surface for the trapezium, and at its outer (radial)
corner presents a tubercle for the insertion of the extensor ossis metacarpi pollicis.
The head of the bone presents on its palmar aspect two shallow grooves for the
sesamoids in the flexor brevis pollicis.
Muscles:-
pari al a
First dorsal interosseous.
Interosseus primus volaris.
Extensor ossis metacarpi pollicis.
Opponens pollicis.
Blood-supply. The nutrient vessel is derived from the princeps pollicis artery:
it enters on the ulnar side, and is directed towards the head of the bone.

144
THE SKELETON
The SECOND METACARPAL is the longest, and is easily recognised by its large
irregular base.
The dorsal surface affords attachment to the tendon of the extensor carpi
radialis longior and a part of the extensor carpi radialis brevior; to the palmar
FIG. 148. THE SECOND (LEFT) METACARPAL.
RADIAL SIDE
FOR TRAPEZIUM
RADIAL SIDE
FOR TRAPEZOID
FIG. 149. THE THIRD (LEFT) METACARPAL.
FOR SECOND METACARPAL
FOR MAGNUM
ULNAR SIDE
FOR THIRD METACARPAL
FOR MAGNUM
ULNAR SIDE
FOR FOURTH METACARPAL
STYLOID PROCESS
surface the tendon of the flexor carpi radialis is inserted. The remaining surfaces
present four articular facets. The end of the bone is occupied by a deep groove
for the trapezoid; the ulnar ridge of this concavity is smooth for the magnum, and
is directly continuous with a long narrow facet for the third metacarpal. The
radial surface of the base has a small, somewhat quadrangular facet for the trapezium.

THE METACARPUS
145
Muscles:--
Flexor carpi radialis.
Extensor carpi radialis longior.
Extensor carpi radialis brevior.
First and second dorsal interosseous.
First palmar interosseous.
Flexor brevis pollicis.
Blood-supply. The nutrient artery is derived from the first palmar inter-
osseous. It enters on the ulnar side, and is directed towards the proximal end or
base of the bone.
The THIRD METACARPAL is easily recognised by the prominent styloid process
which projects from the radial corner of the dorsal surface of the base. A little
below this process the extensor carpi radialis brevior finds insertion. The carpal
surface of the base is nearly plane for the magnum. The radial surface has a long
narrow facet for the second metacarpal. On the ulnar side, two rounded facets are
usually seen for the fourth metacarpal. Not infrequently one of them is absent.
Muscles:-
Extensor carpi radialis brevior.
Second and third dorsal interosseous.
Adductor pollicis.
FIG. 150.-THE FOURTH (LEFT) METACARPAL.

FOR UNCIFORM
RADIAL SIDE
FOR THIRD METACARPAL
FOR MAGNUM
FOR MAGNUM
ULNAR SIDE
FOR FIFTH METACARPAL
Blood-supply. The nutrient artery is derived from the interosseous: it enters,
as a rule, on the radial side, and is directed towards the base.
The FOURTH METACARPAL has a very small base. By its carpal surface it arti-
culates with the unciform. The radial surface has two rounded facets for the third
metacarpal; there is a small facet for the magnum at the posterior radial corner.
The ulnar side has a narrow articular surface for the fifth metacarpal.
Muscles:-
The third dorsal interosseous.
The fourth dorsal interosseous.
The third palmar interosseous.
Blood-supply. The nutrient artery is furnished by the second interosseous; it
enters on the radial side of the shaft, and is directed towards the proximal end.
The FIFTH METACARPAL is readily distinguished. The carpal facet is convex
for the unciform. The ulnar aspect of the base forms a rounded tubercle for the
extensor carpi ulnaris, whilst the radial side has a semilunar facet for the fourth
L

146
THE SKELETON
metacarpal bone. The radial border of the dorsal surface of the shaft often has a
prominent lip for the fourth dorsal interosseous muscle.
Muscles:-
Flexor carpi ulnaris.
Extensor carpi ulnaris.
Fourth dorsal interosseous.
Third palmar interosseous.
Opponens minimi digiti.
Blood-supply. The nutrient artery is derived from the third interosseous. It
enters the shaft on the radial side, and is directed towards the proximal end.
Ossification. Each metacarpal is ossified from two centres. The nucleus for
the shaft appears about the eighth week of embryonic life. At birth the shafts are
FIG. 151. THE FIFTH (LEFT) METACARPAL.
RADIAL SIDE
FOURTH METACARPAL
FOR THE UNCIFORM
ULNAR SIDE
well ossified, but each end is capped by a piece of cartilage. In the case of the
first metacarpal, a centre for the epiphysis appears at the proximal end in the
course of the third year. The bases of the remaining metacarpals are ossified
from the shaft, but an epiphysis forms for the head of each bone in the third year.
The bones are usually consolidated by the twentieth year.
In many cases the first metacarpal has two epiphyses, one at the base and an
additional one at the head; the latter is never so large as in the other metacarpal
bones.
The third metacarpal occasionally has an additional nucleus for the prominent
styloid process which constitutes such a distinguishing feature of this bone.
The styloid process sometimes remains distinct, and is then known as the
styloid bone. Occasionally it fuses with the trapezoid or magnum.
THE PHALANGES
The phalanges are the bones of the fingers. They number in all fourteen: the
thumb has two, the other fingers three each.
Each phalanx has a shaft, which is broad and slightly concave on the palmar,
rounded and smooth on the dorsal aspect. The sides of the palmar surface are
raised where they give attachment to the sheaths of the flexor tendons. The
bases of the phalanges of the first row present glenoid fossæ which play upon the
convex heads of the metacarpals. Their distal ends are surmounted by miniature
condyles.

THE PHALANGES
147
FIG. 152. THE PHALANGES OF THE THIRD DIGIT OF THE HAND. (Dorsal view.)

THIRD TERMINAL OR
UNGUAL PHALANX

SECOND PHALANX

FIRST PHALANX
1.
FIG. 153. OSSIFICATION OF THE METACARPALS AND PHALANGES.
APPEARS IN THE THIRD YEAR.
CONSOLIDATES IN THE TWEN-
TIETH YEAR
APPEAR IN THE THIRD, AND
CONSOLIDATE IN THE TWEN-
TIETH YEAR
EPIPHYSIS FOR BASE
APPEAR BETWEEN THE THIRD
AND FIFTH YEAR. CONSOLI-
DATE IN THE
YEAR
EIGHTEENTH
METACARPAL OF
THUMB
EPIPHYSIS FOR HEAD
L 2

148
THE SKELETON
The phalanges of the second row are shorter than those of the first row.
Their bases present two shallow pits, separated by a ridge.
The terminal, third, or ungual phalanges have an expanded shaft for the
support of the nail. The bases are identical in shape with those of the second row.
Ossification. Each phalanx ossifies from two centres: one for the shaft,
which is deposited between the eighth and tenth week; and a nucleus for the
epiphysis at the proximal end, which appears between the third and fifth years.
Consolidation begins at the seventeenth, and is complete by the eighteenth year.
The ossification of the terminal phalanx is peculiar. Like the other phalanges
it has a nucleus for the shaft and a secondary nucleus for the epiphysis; but the
centre for the shaft appears at the tip of the phalanx; whereas in the other
phalanges the earthy matter is deposited in the middle of the shaft.
THE HIP-BONE
The hip-bone (innominate bone) is of irregular shape, resembling somewhat the
blade of a screw propeller. It consists of three parts, which, though separate in
early life, are, in the adult, firmly ankylosed. The three parts meet together at
the cotyloid cavity or acetabulum. They are named ilium, ischium, and pubes.
The ilium is the upper expanded portion; it articulates with the sacrum, and
forms the upper two-fifths of the acetabulum. The ischium is the lowest part of the
bone; it forms the posterior and inferior two-fifths of the acetabulum, and assists
the pubes to form the obturator foramen. The pubes forms the anterior one-fifth
of the acetabulum, completes the obturator foramen, and stretches towards the
median line to meet with the opposite pubes to form a symphysis. Each part
requires separate consideration.
The ilium has two surfaces: the external surface, or dorsum, is convex in its
general contour. It is limited superiorly by the semicircular crest, and is crossed
by the three gluteal ridges. The superior gluteal ridge commences at the crest
about 5 cm. (2) from its posterior termination, and passes downwards to the
middle of the greater sciatic (ilio-sciatic) notch. The space included between this
ridge and the crest gives origin to the gluteus maximus, and at its lower part to a few
fibres of the pyriformis. The middle gluteal ridge extends from the crest 2.5 cm. (1")
behind its anterior extremity, and passes across the dorsum to terminate near the
posterior end of the superior gluteal ridge, at the greater sciatic notch. The surface
of bone between this ridge and the crest is for the origin of the gluteus medius. The
inferior gluteal ridge begins in the notch separating the anterior iliac spines, and
terminates posteriorly in the middle of the greater sciatic notch. The space between
the middle and inferior ridges gives origin to the gluteus minimus, except a small
area adjacent to the anterior superior iliac spine for the tensor vagina femoris.
The bone between the inferior gluteal ridge and the margin of the acetabulum
affords attachment to the capsule of the hip-joint. Towards its anterior part there
is a rough surface for the reflected tendon of the rectus.
psoas
The internal surface of the ilium consists of an anterior concave portion, termed
the iliac fossa; it lodges the iliacus muscle. The fossa is limited below by the
ilio-pectineal line; this line receives, at its anterior part, the insertion of the
parvus. A small portion of the ilium extends below the ilio-pectineal line to meet.
the ischium. The surface posterior to the fossa is divided into an auricular surface
for articulation with the lateral aspect of the upper portion of the sacrum, and a
superior rough surface-the tuberosity--for the posterior sacro-iliac and ilio-lumbar

THE HIP-BONE
149
ligaments. The crest extends from the anterior superior iliac to the posterior
superior iliac spine. It is thickest at its extremities. The prominent edges, or
lips, are for the attachment of muscles and fasciæ.
The outer lip affords attachment to the gluteal portion of the fascia lata. The
external oblique is inserted into the anterior, and the latissimus dorsi arises from
the posterior half of this lip of the crest. The anterior two-thirds of the inter-
mediate space gives origin to the internal oblique. The inner lip, by its anterior
three-fourths, gives attachment to the transversalis; behind this is a small surface
for the quadratus lumborum, and the remainder is occupied by the erector spina.
The extreme inner margin of the lip serves for the attachment of the iliac fascia.
The anterior border of the ilium extends from the anterior superior spine to
the margin of the acetabulum. The anterior superior spine gives attachment to
Poupart's ligament, and the sartorius which also arises from the upper half of the
superior iliac notch. This notch is terminated inferiorly by the anterior inferior
spine: it is smaller, less prominent than the superior, and gives origin to the
straight head of the rectus femoris and the main limb of the ilio-femoral band of
the capsule of the hip-joint. Beneath the inferior iliac spine is the inferior iliac
notch; it is broad, but shallow, and limited by an eminence, the ilio-pubal ridge,
which indicates the line of ankylosis of the pubes and the ilium. A few fibres of the
iliacus arise from this notch.
The posterior border of the ilium presents above the posterior superior spine,
which gives attachment to the greater sacro-sciatic ligament and the multifidus
spine, and a portion of the oblique sacro-iliac ligament. Below this is a shallow
notch terminating below in the posterior inferior spine, corresponding to the pos-
terior border of the auricular surface. This spine receives a portion of the greater
sacro-sciatic ligament. Below the spine the posterior border of the ilium forms
the upper segment of the greater sciatic notch.
The ischium consists of a thick solid body, a prominent tuberosity, and a ramus.
The body is triangular; its outer surface forms the posterior and inferior section
of the acetabulum. The inner surface forms part of the true pelvis, and meets the
ilium a little distance below the ilio-pectineal line. It also forms the floor, or
non-articular portion, of the acetabulum, and meets the pubes anteriorly; the line
of junction is frequently indicated in adult bones by a rough line extending from
the ilio-pubal ridge to the margin of the obturator foramen. The free border of
this surface forms the posterior boundary of the obturator foramen. The inner
surface of the ischium gives origin to the obturator internus. The posterior surface
of the ischium lies between the posterior rim of the acetabulum and the greater
sciatic notch. Inferiorly this surface is limited by the obturator groove, which
receives the posterior fleshy border of the obturator externus when the thigh is
flexed. The capsule of the hip-joint is attached to the outer part of the posterior
surface. The pyriformis, the greater and lesser sciatic nerves, the sciatic artery,
and the nerve to the quadratus femoris, cross it. The inner border assists the
ilium to complete the greater sciatic notch, which is terminated inferiorly by
the prominent ischiatic spine, which gives attachment to the lesser sacro-sciatic
ligament, the levator ani, and coccygeus. From the base of the spine, posteriorly,
the gemellus superior arises; and the internal pudic vessels and nerve, with the
nerve to the obturator internus, cross it. The recess below the ischiatic spine is
the lesser sciatic notch; in the recent state it is covered with cartilage, and
presents two, three, or four grooves for the tendinous under surface of the obturator
internus muscle.
The tuberosity is that portion of the ischium which supports the body in the
sitting posture. It has an inner and an outer lip, and an intermediate space which
presents two rough surfaces; of these, the upper and outer is for the origin of the
semi-membranosus, and the lower and inner surface for the conjoint origin of the


150
THE SKELETON
biceps and semitendinosus. Above the surface for the semimembranosus, the
tuberosity gives origin to the gemellus inferior. Its inner edge, or lip, is pro-
minent, and gives attachment to the falciform edge of the greater sacro-sciatic
ligament. The surface of the tuberosity above this lip is in relation with the
internal pudic vessels and nerves. The outer lip is occupied by the quadratus
FIG. 154. THE LEFT HIP-BONE. (Internal surface.)
Quadratus lumborum
Erector spinæ
TUBEROSITY
Multifidus
spinæ
AURICULAR
SURFACE
POST. INF. SPINE
OF ILIUM
Obturator
internus
Coccygeus
Levator ani
GROOVE FOR
PUDIC VESSELS
AND NERVE
Gt. sacro-sciatic
ligament
TUBEROSITY OF
ISCHIUM
Transversus
perinei
ILIUM-
ILIAC
FOSSA
ISCH UM
Transversalis
and the
iliac fascia
Iliacus
ANT. SUP.
SPINE OF
ILIUM
THYROID
FORAMEN
PUBES
JUNCTION OF
Crus penis
and
Com- Sub-pubic
pressor
ligament
PUBES AND
ISCHIUM
Erector penis urethræ
ANT. INF. SPINE
OF ILIUM
Psoas minor
ILIO-PUBAL RIDGE
GROOVE FOR
OBTURATOR
NERVE AND
VESSELS
SYMPHYSIAL
SURFACE
Levator ani
femoris muscle, and the surface adjacent to this is occupied by the adductor
magnus. The surfaces thin away to a sharp margin, which forms part of the
boundary of the obturator foramen.
The ramus of the ischium is a continuation of the tuberosity running upwards
to join the descending ramus of the pubes, to complete the obturator foramen. The
outer surface of the ramus gives origin to the adductor magnus and the obturator

THE HIP-BONE
151
externus. To its inner surface the crus penis is attached; it also gives origin to
the transversus perinei, the erector penis, and the obturator internus.
The pubes consists of a body and two rami. The body, quadrilateral in shape,
is continuous with the ramus of the ischium by means of a flattened process termed
the descending ramus. The outer surface of the body gives origin to the adductor
longus. The adductor brevis, the gracilis, and the obturator externus arise from the
FIG. 155. THE LEFT HIP-BONE. (Posterior view.)
Posterior limit of external oblique
Insertion of
external oblique
Internal oblique.
Tensor vaginæ
femoris
Sartorius
Rectus femoris
MIDDLE
Gluteus
minimus
Gluteus
mediu's
GLUTEAL
LINE
INFERIOR GLUTEAL LINE
INFERIOR ILIAC
NOTCH
Rectus
Latissimus
dorsi
CREST OF ILIUM
SUPEROR
GLUTEAL
RIDGE
Gluteus
maximus
POSTERIOR
SUPERIOR
ILIAC SPINE
Pyriformis
POSTERIOR
INFERIOR
ILIAC SPINE
GREATER SCIATIC
(ILIO-SCIATIC) NOTCH
ARTICULAR PORTION
OF COTYLOID
CAVITY
Capsule
Synovial
membrane
PECTINEAL RIDGE
Pectineus
Rectus abdo-
minis
Pyramidalis
Adductor
longus
Adductor
brevis
DESCENDING RAMUS
OF PUBES
Gracilis
COTYLOID
FOSSA
COTYLOID NOTCH
THYROID
FORAMEN
ISCHIUM
SPINE OF ISCHIUM
Gemellus superior
LESSER SCIATIC NOTCH
Gemellus inferior
OBTURATOR NOTCH
Semimembranosus
Quadratus femoris
Semitendinosus
and biceps
Adductor magnus
RAMUS OF ISCHIUM
Obturator externus
outer surface of the body and descending ramus. A small portion of the adductor
magnus also arises from the descending ramus. The posterior surface of the body
and that of the descending ramus is continuous with the corresponding surface of
the ramus of the ischium, and affords attachment to the levator ani and obturator
internus. The posterior surface of the descending ramus gives origin to the com-
pressor urethra and a part of the erector penis, the crus penis, and the obturator

152
THE SKELETON
internus. The inner border is rough and covered with fibro-cartilage, which
unites it with the opposite bone to form the pubic symphysis. The outer border
forms part of the obturator foramen. The inner border of the descending ramus
forms with the ramus of the ischium the pubic arch.
FIG. 156.-AN IMMATURE INNOMINATE BONE, SHOWING A COTYLOID BONE.
THE COTYLOID BONE
The upper surface or crest of the pubes is limited externally by the pubic spine,
which gives attachment to the outer (inferior) pillar of the external abdominal ring
and Poupart's ligament. The inner extremity of the crest is the angle of the
pubes. Between it and the spine the following structures are attached :-the linea
FIG. 157. THE PELVIS OF A FETUS AT BIRTH, TO SHOW THE THREE PORTIONS
OF THE INNOMINATE BONES.
-THE NUCLEUS FOR THE ILIUM
APPEARS EARLY IN THE
THIRD MONTH
THE NUCLEUS FOR THE PUBES
APPEARS ABOUT THE END OF
THE FOURTH MONTH
THE NUCLEUS FOR THE ISCHIUM
APPEARS IN THE THIRD MONTH
alba, the rectus abdominis, the pyramidalis, and the conjoined tendon. The hori-
zontal ramus extends from the body of the pubes to the ilium, forming by its outer
extremity the anterior one-fifth of the articular surface of the acetabulum. Its

THE HIP-BONE
153
line of junction with the ilium forms the ilio-pubal ridge. Stretching from this
ridge to the pubic spine there is a raised edge continuing the ilio-pectineal line. The
surface of bone in front of the line is the pectineal surface; it gives origin to the
pectineus muscle, and is limited below by the obturator crest, which extends from
the pubic spine to the cotyloid notch. The under surface of the horizontal ramus
forms the upper boundary of the obturator foramen, and presents a deep groove
for the passage of the obturator vessels and nerve.
The acetabulum is a circular depression in which the head of the femur is
lodged. It consists of an articular and a non-articular portion. The articular
portion is circumferential and horseshoe-shaped; the deficiency is in the lower
segment. The pubes forms one-fifth of the acetabulum, and the ischium two-
fifths; the rest is formed by the ilium. In rare instances the pubes may be
excluded by a fourth element, the cotyloid bone. The non-articular portion is
formed mainly by the ischium, and is continuous below with the margin of the
obturator foramen. The articular portion presents an outer rim to which the
cotyloid ligament is attached, and an inner margin to which the synovial
membrane is connected which excludes the ligamentum teres from the synovial
cavity. The opposite angles of the horseshoe-shaped margin which limit the
cotyloid notch are united by the transverse ligament, and through the cotyloid
foramen thus formed a nerve and vessel enter the joint.
The obturator (thyroid) foramen is situated between the ischium and pubes
Its margins are thin, and serve for the attachment of the obturator membrane. At
the upper and posterior angle it is deeply grooved for the passage of the obturator
vessels and nerve.
Muscles attached to the hip-bone are:-
Gluteus maximus.
Gluteus medius.
Gluteus minimus.
Tensor vaginæ femoris.
Rectus femoris.
Obturator externus.
Obturator internus.
Sartorius.
Pectineus.
Pyramidalis.
Pyriformis.
Gemellus superior.
Gemellus inferior.

Gracilis.
Latissimus dorsi.
Internal oblique.
External oblique.
Transversalis.
Erector spinæ.
Multifidus spinæ.
Quadratus lumborum.
Iliacus.
Psoas parvus.
Quadratus femoris.
Accelerator urinæ (occasionally).
The ligaments attached to the hip-bone are:-
Greater sacro-sciatic.
Ilio-lumbar.
Adductor magnus.
Adductor longus.
Adductor brevis.
Levator ani.
Coccygeus.
Transversus perinei.
Erector penis.
Compressor urethræ.
Biceps femoris.
Semitendinosus.
Semimembranosus.
Transverse.
Round (ligamentum teres).
Anterior pubic.
Posterior pubic.
Lesser sacro-sciatic.

Anterior sacro-iliac.
Posterior sacro-iliac.
Superior pubic.
Capsular and its accessories.
Subpubic.
Cotyloid.
Triangular.
Poupart's.

154
THE SKELETON
Blood-supply. The ilium receives on its anterior surface twigs from the ilio-
lumbar, deep circumflex iliac, and obturator arteries. On the dorsum, arteries
enter it from the gluteal and sciatic trunks.
The ischium is supplied by the obturator, internal, and external circumflex.
The pubes receives twigs from the obturator, internal and external circumflex,
deep epigastric, and the pubic branches of the common femoral artery.
Development. The cartilaginous representative of the hip-bone consists at first
of an ilio-ischiatic and a pubic segment. These quickly fuse and form a continuous
plate (Rosenberg). Early in the third month a nucleus appears above the acetabulum
for the ilium, and one appears a little later below the cavity for the ischium. In
the fourth month a nucleus is seen in the pubic portion of the cartilage. At birth
these three nuclei are of considerable size, but surrounded by relatively wide tracts of
FIG. 158.-HIP-BONE, SHOWING SECONDARY CENTRES.
APPEARS AT FIFTEEN. UNITES
AT TWENTY
APPEARS AT FIFTEEN. UNITES
AT TWENTY
THE LINES OF UNION ARE-
USUALLY OBLITERATED BY
THE SIXTEENTH YEAR
APPEARS AT SIXTEEN.
FUSES AT TWENTY
APPEARS AT FIFTEEN.
FUSES AT TWENTY
ILIUM
cartilage. In the sixth year the Y-shaped piece of cartilage in the acetabulum ossifies,
and, uniting with the three surrounding elements, causes their consolidation, usually
about the sixteenth year. When this nucleus is large, it may remain separate until
after the twentieth year. This is the acetabular nucleus, and is regarded by some
morphologists as the representative of the cotyloid or acetabular bone constantly
present in a few mammals, and is of sufficient size to excludes the pubes from the
cotyloid cavity. During the eighth year the rami of the ischium and pubes coalesce.
About the fifteenth year two secondary nuclei appear in the iliac cartilage to form
the crest and the anterior inferior spine. An accessory nucleus appears for the
ischial tuberosity, and subsequently one for the pubic crest. These fuse with the
main bone about the twentieth year. The fibrous tissue connected with the pubic
spine represents the epipubic bone of marsupial mammals.

THE PELVIS
155
THE PELVIS
The pelvis is composed of four bones: the two hip-bones, the sacrum, and coccyx.
The hip-bones form the lateral and anterior boundaries, meeting each other to form
the pubic symphysis; posteriorly they are separated by the sacrum.
of the pelvis is divided into the false and true pelvic cavity.
The hollow
The false pelvis is that part of the cavity which lies above the ilio-pectineal
lines; this part is in relation with the hypogastric and inguinal regions.
The true pelvis is situated below the ilio-pectineal lines. The upper circum-
ference, called also the inlet of the pelvis, is bounded anteriorly by the spine and
crest of the pubes, posteriorly by the base of the sacrum, and laterally by the ilio-
pectineal lines. The inlet in normal pelves is cordate, being obtusely pointed in
front; posteriorly it is encroached upon by the promontory of the sacrum. It has
three principal diameters: of these, the antero-posterior, called the conjugate
diameter, is measured from the sacro-vertebral angle to the symphysis. The trans-
FIG. 159. THE PELVIS (MALE).
verse diameter represents the greatest width of the pelvic cavity. The oblique is
measured from the sacro-iliac synchondrosis to the ilio-pubal ridge.
The cavity of the true pelvis is bounded in front by the symphysis pubis, behind
by the sacrum and coccyx, and laterally by a smooth wall of bone formed in part
by the ilium, in part by the ischium; it corresponds to the acetabulum. The cavity
is shallow in front, where it is formed by the pubes, and is deepest posteriorly.
The lower circumference, or outlet, of the pelvis is very irregular, and encroached
upon by three bony processes: the posterior process is the coccyx, and the two lateral
processes the ischial tuberosities. They separate three notches. The anterior
is the pubic arch, and is bounded on each side by the conjoined rami of the
pubes and ischium on each side. The two remaining gaps correspond to the
greater and lesser sciatic notches; they are bounded by the ischium anteriorly, the
sacrum and coccyx posteriorly, and the ilium above. These are converted into
foramina by the greater and lesser sacro-sciatic ligaments.

156
THE SKELETON
The position of the pelvis.--In the erect position of the skeleton, the plane of
the pelvic inlet forms an angle with the horizontal, which varies in individuals from
50° to 60°. The base of the sacrum in an average pelvis lies nearly 10 cm. (4")
above the upper margin of the symphysis pubis.
The axis of the pelvis.-This is an imaginary line drawn at right angles to the
planes of the brim, cavity, and outlet, through their centres.
The average measurements of the diameters of the pelvis in the three planes are
given below (after Lusk):-
Diameters
Conjugate
Transverse
At the brim
4 inches
At the outlet
5
29
5
99
Oblique
33 inches
44
4/1/
Sex differences. In the male the pelvis is deeper, the ridges for muscles more
marked, and the bones thicker, than in the female. In the male, the obturator
foramen is described as vertically ovate, the pubic symphysis is deep, and the pubic
arch small.
In the female, the bones are thinner, lighter, and the iliac alæ more expanded
than in the male. The symphysis is narrow, the pubic arch wider, and the ischial
tuberosities more expanded than in the male. The obturator foramen is described
as triangular. The pelvic cavity is larger in most of its measurements. The
sacrum is wider, less curved as a rule, and has a less projecting promontory
than in the male.
THE FEMUR
This bone is the largest and longest in the skeleton. The upper extremity
is surmounted by a hemispherical cartilage-covered articular portion called the
head, which is directed upwards and inwards, to be received in the acetabulum of
the hip-bone. A little below the centre of the head is a small rough depression
to which the ligamentum teres is attached. The head is connected to the shaft
by the neck, a stout rectangular process of bone which forms with the femoral
shaft, in the adult, an angle of 125°. Its anterior surface is in the same plane
with the front aspect of the shaft, but it is marked off from it by a ridge to which
the capsule of the hip-joint is attached. This ridge commences at the greater
trochanter in a small prominence, the superior cervical tubercle, and extends
obliquely downwards to the inferior cervical tubercle, and, winding to the back of
the femur, becomes continuous with the inner lip of the linea aspera. The whole
of this ridge is called the spiral line, but the part between the cervical tubercles is
often called the anterior intertrochanteric line. The superior and inferior tubercles
receive the limbs of the ilio-femoral or Y-shaped thickening in the capsule of the
hip-joint. The posterior surface of the neck is smooth and concave, its inner half
is enclosed in the capsule of the hip-joint. The superior surface is narrow, and
pitted with nutrient foramina; it runs downward to the greater trochanter. The
inferior surface, concave in outline, terminates at the lesser trochanter.
The trochanters are prominences which afford attachment to muscles which
rotate the thigh; they are two in number, the greater and the lesser.
The greater trochanter is quadrilateral, and surmounts the junction of the
neck with the shaft. Of its two surfaces, the external is the broader; it is bisected
diagonally by a ridge running from the posterior superior to the anterior inferior

THE FEMUR
157
angle. The gluteus medius is inserted into this ridge; a bursa occasionally inter-
poses between the tendon and the bone. The inner surface presents a deep pit, the
trochanteric fossa, which receives the tendon of the obturator externus. The upper
border, called the tip, gives attachment from before backwards to the tendons of
the obturator internus with the gemelli, and the pyriformis. The anterior border
receives the gluteus minimus. The posterior border is thick, rounded, and con-
tinuous with the posterior intertrochanteric line, which runs downwards to terminate
at the lesser trochanter, a conical prominence on the posterior aspect of the femur
to which the psoas is inserted. Running downwards from the lesser trochanter to
meet the spiral line is a slender ridge, to which the iliacus is inserted. The
surface of bone slightly posterior to this ridge is occupied by the pectineus. This
part of the femur presents several converging ridges, which will be most con-
veniently considered with the linea aspera.
aspera
The shaft of the femur is cylindrical in shape, and presents, in the middle
third of its posterior aspect, a prominent vertical ridge of bone, the linea aspera,
for the origin and insertion of muscles. In the middle of the shaft the linea
presents an inner lip, an outer lip, and an intervening space. Towards the upper
third of the shaft these three parts diverge: the outer lip becomes continuous with
the gluteal ridge, and ends at the base of the greater trochanter.
When very
prominent the gluteal ridge is termed the third trochanter. It affords attachment
to the gluteus maximus. The inner lip curves inwards below the lesser trochanter,
and becomes the spiral line. The middle portion of the linea aspera bifurcates, the
inner portion as it runs on to the lesser trochanter receives the iliacus; the outer
passes upwards to the centre of the posterior intertrochanteric line; it receives
the quadratus femoris, and is called the linea quadrati. The upper limit of this
line is often indicated by a rounded tubercle. Towards the lower third of the shaft,
the inner and outer lips of the linea aspera diverge to become continuous with the
condylar ridges. Several muscles are connected with the linea aspera. The vastus
internus arises from the whole length of the inner lip, and the vastus externus
from the outer lip. The adductor magnus is inserted into the upper half of the
outer lip, and the lower half of the inner lip. The adductor longus and brevis are
inserted into the intervening space; the adductor longus takes rather more than
the middle third, and overlaps the lower part of the adductor brevis, which takes
rather more than the upper third. The outer lip in its lower two-thirds gives origin
to the shorter head of the biceps. The condylar lines are two in number; the
outer is continuous with the outer lip of the linea aspera and terminates inferiorly
on the outer edge of the external condyle. From the upper half of this line a part
of the short head of the biceps arises. Near its termination the line expands to give
origin to the plantaris and the outer head of the gastrocnemius. The inner
condylar line is not so prominent as the outer; it is continuous with the inner lip
of the linea aspera, and terminates at the adductor tubercle. The adductor magnus
is inserted into the whole length of the line and to the tubercle. Near the middle
of the line there is an interruption where the femoral artery passes through the
opening in the tendon of the adductor magnus. The inner head of the gastro-
cnemius arises from the femur immediately above the internal condyle. The space
enclosed between these diverging lines forms part of the anterior boundary of the
popliteal space, and is in close relation with the popliteal vessels. The shaft of the
femur is overlapped on the inner side by the vastus internus, and on the outer side
by the vastus externus. The greater part of the anterior surface of the femoral
shaft affords origin to the crureus.
The lower extremity presents two cartilage-covered condyles, separated by a
deep notch. The external condyle is more prominent anteriorly and wider than
its fellow. The internal is more prominent posteriorly, and narrower; it is also
longer, to compensate for the obliquity of the shaft. When the femur is properly


FIG. 160.-THE LEFT FEMUR. (Anterior view.)
HEAD
GREATER TROCHANTER
Pyriformis
Obturator internus
SUPERIOR CERVICAL TUBERCLE.
NECK
Gluteus minimus
Capsule
OF THE HIP-JOINT ATTACHED TO THE ANTERIOR
INTERTROCHANTERIC LINE
LESSER TROCHANTER
Psoas
ADDUCTOR TUBERCLE
Adductor magnus
GRUREUS
SUB-CRUREUS
PATE
TELLAR PACET
INTERNAL CONDYLE
EXTERNAL CONDYLE
Vastus externus
External lateral ligament
Popliteus

FIG. 161.-THE LEFT FEMUR. (Posterior view.)
Obturator internus
Gluteus medius
NECK
TUBERCLE OF THE
quadratus femoris
HEAD
Ligamentum teres
Capsule
Vastus externus
GLUTEAL RIDGE
Gluteus maximus
POSTERIOR INTERTROCHANTERIC LINE
Psoas
LESSER TROCHANTER
Iliacus
Pectineus
Adductor magnus
Adductor brevis
OUTER LIP OF THE LINEA ASPERA
Biceps
INTERVENING SPACE OF THE
LINEA ASPERA
Adductor longus
Biceps
EXTERNAL CONDYLAR LINE
Plantaris
Gastrocnemius.
Anterior crucial ligament-
INTERCONDYLOID NOTCH-
POPLITEAL SURFACE
Vastus internus
INNER LIP OF THE LINEA ASPERA
NUTRIENT FORAMINA
FOR FEMORAL ARTERY
INTERNAL CONDYLAR LINE
Adductor magnus
ADDUCTOR TUBERCLE
Gastrocnemius
Internal lateral ligament
EXTERNAL CONDYLE
INTERNAL CONDYLE
Posterior crucial ligament

160
THE SKELETON
articulated, the inferior surfaces of the condyles are nearly on the same plane, and
almost parallel to come into contact with the articular surfaces on the head of the tibia.
Posteriorly the condyles are separated by a deep pit or notch; anteriorly they are
united by an articular surface, over which the patella glides. The inner surface of
the internal condyle has, near its posterior border, a rough surface for the internal
lateral ligament of the knee joint; above this is the adductor tubercle. The
surface of this condyle, which bounds the intercondyloid notch, affords attachment,
FIG. 162.-THE FEMUR AT BIRTH.
APPEARS EARLY IN THE NINTH MONTH OF INTRA-UTERINE LIFE
near the anterior border, to the posterior crucial ligament. The surface of the
external condyle which bounds the notch gives attachment, at its posterior part,
to the anterior crucial ligament. The outer surface of the external condyle
presents near the lower and posterior margin a deep groove, which receives the
tendon of the popliteus muscle when the leg is flexed. The groove is sur-
mounted by a tubercle for the external lateral ligament of the knee.
The patellar facet is trochlear in shape; its outer portion is more extensive
than the inner, corresponding to the disposition of the articular facets on the
posterior surface of the patella.

THE FEMUR
161
Muscles attached to the femur:-
Pyriformis.
Obturator internus and gemelli.
Obturator externus.
Pectineus.
Quadratus femoris.
Gluteus maximus.
Adductor brevis.
Vastus internus.
Adductor magnus.
Adductor longus.
Vastus externus.
Crureus and subcrureus.
Gluteus medius.
Gluteus minimus.
Psoas.
Iliacus.
Biceps.
Gastrocnemius.
Plantaris.
Popliteus.
FIG. 163. THE LEFT FEMUR AT THE TWENTIETH YEAR. (Posterior view.)

APPEARS IN THE FIRST, AND FUSES
IN THE TWENTIETH YEAR
APPEARS IN THE FOURTH, AND
UNITES IN THE NINETEENTH YEAR
APPEARS IN THE FOURTEENTH,
AND UNITES IN THE EIGHTEENTH
YEAR
APPEARS EARLY IN THE NINTH MONTH
OF INTRA-UTERINE LIFE, AND UNITES
AT THE TWENTY-FIRST YEAR
Ligaments:-
Capsular of hip-joint.
Ligamentum teres.
Internal lateral of knee-joint.
External lateral of knee-joint.
Anterior crucial.
Posterior crucial.
Posterior, or Winslow's.
Blood-supply. The head and neck of the femur receive branches from the
sciatic, obturator, and circumflex arteries. The trochanter receives twigs from the
circumflex arteries. The nutrient vessel for the shaft is derived from the second
M

162
THE SKELETON
perforating; it enters near the middle of the linea aspera, and is directed towards
the head of the bone. The condyles are nourished by articular branches from the
popliteal and the anastomotic of the femoral.
-
Ossification. The shaft of the femur begins to ossify in the seventh week of
intra-uterine life. Early in the ninth month a nucleus appears for the condyles.
During the first year the nucleus for the head of the bone is visible, and one for
the greater trochanter in the fourth year. The centre for the lesser trochanter is
visible about the thirteenth or fourteenth year. The lesser trochanter joins the
shaft at the eighteenth, the greater trochanter at the nineteenth, the head about
the twentieth, and the condyles at the twenty-first year.
The neck of the femur is an apophysis, or outgrowth from the shaft. The line
of fusion of the condyloid epiphysis lies below the adductor tubercle, so that the
tubercle with the spaces from which the gastrocnemius and plantaris arise, belong
to the shaft, and not to the epiphysis.
The morphological relation of the patellar facet to the articular portions of the
condyles is worth notice. In a few mammals, such as the ox, this facet remains
separated from the condyles by a furrow of rough bone. In the human femur it is
faintly marked off by a shallow groove in the cartilage, best seen in a recently
opened knee-joint. Some anatomists attribute these grooves in the cartilage to
the pressure of the semilunar fibro-cartilages.
The angle which the neck of the femur forms with the shaft measures at birth,
on an average, 160°. In the adult it varies from 110° to 140°; hence the angle
decreases greatly during the period of growth. When once growth is completed,
the angle, as a rule, remains fixed. (Humphry.)
THE PATELLA
The patella is a sesamoid bone, somewhat triangular in shape, situated in
front of the knee-joint. Its anterior surface is slightly convex, and pitted with
FIG. 164. THE LEFT PATELLA.
Anterior surface
Posterior surface
EXTERNAL ARTICULAR FACET
INTERNAL
ARTICULAR
FACET
LATERAL FACET
FOR INTERNAL
CONDYLE
FOR THE
PATELLAR
LIGAMENT
small openings, which transmit nutrient vessels to the interior of the bone. This
surface is subcutaneous; a bursa intervenes between it and the skin. The posterior
surface is concave, and in great part cartilage-covered, forming a compound
THE PATELLA
163
articular surface for gliding upon the femoral condyles. A slightly marked vertical
ridge divides this surface into an outer larger portion for the external condyle, and
an inner portion for the internal condyle. A slender articular facet close to the
inner edge is sometimes marked off by a faint vertical ridge; this facet comes
in contact with the internal condyle in extreme flexion of the leg. The lower
part of the bone is produced to a blunt point, which is embedded in the patellar
ligament, especially on the posterior aspect. The upper two-thirds of the circum-
ference receives directly the fibres of the vastus internus and externus, the
crureus and rectus femoris muscles.
Blood-supply. The patella receives twigs from the superficial branch of the
anastomotica, anterior tibial recurrent, and the inferior articular of the popliteal.
Ossification.--The cartilage for the patella appears in the fourth month of
intra-uterine life. The ossific nucleus is visible in the third year.
THE TIBIA
The tibia is the larger bone of the leg; it is situated on the inner side of, and
nearly parallel with, the fibula. The upper extremity, or head, consists of two
lateral eminences, or tuberosities. The superior surfaces of the tuberosities receive
the condyles of the femur, the articular surfaces being separated by a non-articular
ridge, to which ligaments are attached. The internal articular surface is oval
in shape and concave for the internal condyle of the femur. The external
articular surface is smaller, somewhat circular in shape, and presents an almost
plane surface for the external condyle. The peripheral portion of each articular
surface is overlaid by a fibro-cartilage of semilunar shape, connected with the
margins of the tuberosities by bands of fibrous tissue termed coronary ligaments.
Each semilunar fibro-cartilage is attached firmly to the rough tract sepa-
rating the articular surfaces. This intermediate space is broad and depressed
in front, where it affords attachment to the anterior limb of the internal and
external semilunar cartilages and the anterior crucial ligament. Standing upwards
from the middle of this surface is the spine of the tibia. The posterior aspect
of the base of the spine affords attachment to the posterior limb of the external
and internal semilunar fibro-cartilages, and limits a deep notch inclined towards
the inner tuberosity; this notch gives origin to the posterior crucial ligament.
Anteriorly, the two tuberosities are confluent, and form a somewhat flattened
surface of triangular outline; its apex forms the tubercle of the tibia. The liga-
mentum patellæ is inserted into the lower part of the tubercle; the upper part is
smooth and separated from the ligament by a bursa. Laterally the inner tuber-
osity is less prominent, though more extensive than the outer; near the posterior
part of its circumference there is a deep horizontal groove for the central portion
of the semimembranosus tendon. The margins of this groove and the surface
of bone below give attachment to the internal lateral ligament of the knee. At a
corresponding point of the outer tuberosity there is a rounded articular facet
for the head of the fibula; the circumference of the facet is rough for ligaments.
The shaft is prismatic, and very thick near the head; towards the lower third it
is thinner and tapering, and gradually expands towards the lower end. It has three
borders: the anterior is very prominent, and known as the crest of the tibia:
commencing on the outer edge of the tubercle, it runs downwards and curves
inwards, to terminate at the anterior margin of the malleolus. This border gives
attachment to the deep fascia of the leg. The internal border starts from the

M 2

164
THE SKELETON
FIG. 165.-THE LEFT TIBIA AND FIBULA. (Anterior view.)
Internal fibro-cartilage
Capsule
Anterior crucial ligament-
INNER TUBEROSITY-
Internal lateral ligament
Ligamentum patellæ
(Quadriceps extensor)
Gracilis
Sartorius
Semi-tendinosus
SPINE OF TIBIA
External fibro-cartilage
Capsule
OUTER TUBEROSITY
Biceps and the
Anterior tibio-fibular ligament
External lateral ligament
-Extensor longus digitorum
EXTERNAL SURFACE OF TIBIA
Tibialis anticus
Peroneus longus
Peroneus brevis
ANTERIOR BORDER OR CREST-
OF THE TIBIA
Extensor longus digitorum
INTERNAL SURFACE OF TIBIA-
PERONEAL SURFACE OF FIBULA
EXTENSOR SURFACE OF FIBULA
Extensor proprius hallucis
Interosseous membrane.
FIBULA
Peroneus tertius
SUBCUTANEOUS PORTION
Anterior tibio-fibular ligament
Capsule.
Internal lateral ligament.
INTERNAL MALLEOLUS-
EXTERNAL MALLEOLUS
External lateral ligament
(Anterior fasciculus)

TIBIA AND FIBULA
165
FIG. 166. THE LEFT TIBIA AND FIBULA. (Posterior view.)
External fibro-cartilage-
Capsule.
Posterior crucial ligament-
STYLOID PROCESS-
Posterior tibio-fibular ligament-
POPLITEAL NOTCH
Internal fibro-cartilage
Capsule
Semi-membranosus
Soleus
Popliteus
Tibialis posticus
OBLIQUE LINE
Soleus
POSTERIOR SURFACE OF TIBIA
Flexor longus hallucis
Flexor longus digitorum
FLEXOR SURFACE OF FIBULA
ENUTRIENT FORAMEN
FIBULA
Peroneus brevis
Posterior tibio-fibular ligament,
GROOVE FOR FLEXOR LONGUS HALLUCIS
External lateral ligament
(posterior fasciculus)
External lateral ligament
(middle fasciculus)
Capsule
-TIEIA
GROOVE FOR TIBIALIS POSTICUS
AND
FLEXOR LONGUS DIGITORUM
Internal lateral ligament

166
THE SKELETON
back of the internal tuberosity, and ends at the posterior margin of the malleolus.
The internal lateral ligament is attached to its upper 7.5 cm. (3"), and the middle
third gives origin to the soleus. The interosseous border extends from the fibular
facet on the outer tuberosity to the lower end of the bone; towards its termination
the border bifurcates to enclose a triangular space for the attachment of the inter-
osseous ligament between the tibia and fibula. The part above the bifurcation is
connected with the interosseous membrane.
These borders limit three surfaces. The internal surface is bounded by the
internal border and the crest; it is broad above, where it receives the insertion of
the sartorius, gracilis, and semitendinosus; the rest of the surface is convex and
subcutaneous. The external surface lies between the crest of the tibia and the
interosseous border. The upper two-thirds presents a hollow for the origin of the
tibialis anticus; the rest of the surface is overlaid by the extensor tendons and the
anterior tibial vessels. The posterior surface is limited by the interosseous
ridge and the internal border. The upper part presents a rough oblique ridge,
extending from the fibular facet on the outer tuberosity to the internal border, a
little above the middle of the bone. This oblique ridge gives origin to the soleus
and attachment to the popliteal fascia; the surface above is for the insertion of the
popliteus. An indefinite vertical ridge commences near the middle of the oblique
line, and marks off a semilunar space, limited externally by the interosseous border.
This is for the tibialis posticus; it extends as low as the junction of the middle
and lower thirds. The portion of bone outside this vertical line is for the
flexor longus digitorum. The lower third of the posterior surface is covered by
flexor tendons.
The inferior extremity is somewhat quadrilateral, and resembles the distal
end of the radius. Its inferior surface is articular for the upper surface of the
astragalus and is continuous with the external surface of the malleolus, which
articulates with the facet on the inner side of the astragalus. The outer surface
has a triangular rough area for the lower end of the shaft of the fibula, its
margins being rough for ligaments. The anterior border is slightly convex, and
by its margin gives attachment to the anterior ligament of the ankle. The posterior
surface has two grooves: the one which encroaches on the malleolus is for the
tendons of tibialis posticus and flexor longus digitorum, and an outer shallow
groove for the tendon of flexor longus hallucis. The inner surface is prolonged
downwards to form the malleolus; from its tip and margins the internal lateral
(deltoid) ligament of the ankle joint arises. The inner surface of the malleolus is
convex and subcutaneous; the outer, as already stated, has a facet for the inner
surface of the astragalus.
The tibia affords attachment to the following muscles:-
Semimembranosus.
Sartorius.
Gracilis.
Semitendinosus.
Quadriceps extensor.
Popliteus.
Tensor vaginæ femoris (indirectly).
Ligaments:-
Anterior crucial.
Posterior crucial.
Internal lateral of the knee.
Internal semilunar cartilage.
External semilunar cartilage.
Tibialis posticus.
Tibialis anticus.
Soleus.
Peroneus longus.
Flexor longus digitorum.
Extensor longus digitorum.
Biceps femoris.
Coronary.
Anterior tibio-fibular (superior).
Posterior tibio-fibular (superior).
Ilio-tibial band.
Interosseous membrane.

TIBIA AND FIBULA
167
Anterior tibio-fibular (inferior).
Posterior tibio-fibular (inferior).
Anterior of ankle.
Anterior annular (vertical).
Anterior annular (oblique).
Transverse.
Internal annular.
Internal lateral of ankle (deltoid).
Posterior (of ankle).
Blood-supply. The tibia is a very vascular bone. The nutrient artery for the
shaft is furnished by the posterior tibial; it enters the bone near the interosseous
FIG. 167.-THE TIBIA AND FIBULA AT THE SIXTEENTH YEAR.

APPEARS AT BIRTH; UNITES AT TWENTY-
ONE; BUT IS SOMETIMES DELAYED TO
TWENTY-FIVE
APPEARS AT THE FIFTH YEAR; UNITES AT
TWENTY-TWO

APPEARS AT SECOND YEAR; UNITES AT
THE EIGHTEENTH YEAR
APPEARS AT THE SECOND YEAR; UNITES
AT TWENTY
border at the junction of the upper and middle thirds, and is directed downwards.
The head of the bone receives numerous branches from the inferior articular
arteries of the popliteal, and the recurrent branches of the anterior and posterior
tibial arteries. The lower extremity receives twigs from the posterior and anterior
tibial, the anterior peroneal, and internal malleolar arteries.
-
Ossification. The centre for the shaft of the tibia appears in the eighth week
of intra-uterine life. Towards the end of the ninth month, a small earthy nucleus

168
THE SKELETON
appears in the cartilaginous head of the tibia. The nucleus for the lower ex-
tremity appears in the second year, and unites with the shaft at eighteen. The
epiphysis for the head of the bone is one of the last to unite with its shaft; this
event usually occurs about the twenty-first year, but may be delayed until twenty-
five. The tubercle of the tibia is usually ossified from the epiphysis; occasionally
it has an independent nucleus.
THE FIBULA
This is a long and slender bone, lying to the outer side of, and nearly parallel
with the tibia; the middle of the shaft is somewhat posterior to that of the tibia.
The upper extremity, or head, is of irregular form, and presents an oblique facet
on its inner aspect for articulation with the outer tuberosity of the tibia; the adjacent
surfaces afford attachment to the superior tibio-fibular ligaments. The outer border
of the head is prolonged into the styloid process, and gives attachment to the
external lateral ligament of the knee; the base of the process receives the biceps
tendon. Near this point a portion of the peroneus longus arises; and posteriorly
the head of the bone gives origin to the upper fibres of the soleus.
The lower extremity, or external malleolus, is a thick, pyramidal process of
bone. Its inner surface presents anteriorly a triangular facet for articulation with
the fibular facet on the outer side of the body of the astragalus. Posterior to this
facet is the malleolar fossa, for the reception of the posterior fasciculus of the
external lateral ligament of the ankle when the foot is extended. This fasciculus
of the ligament arises from the margin of the fossa. Above the facet, the bone
is rough for the inferior tibio-fibular ligaments. The outer surface is subcutaneous.
The anterior surface gives attachment to the anterior fasciculus of the external
lateral ligament of the ankle. The posterior surface has a shallow groove for
the passage of the tendons of the peroneus longus and brevis. The tip of the
malleolus gives attachment to the middle fasciculus of the external lateral
ligament of the ankle. In the adult the fibular malleolus projects lower, and is
more prominent than the tibial malleolus.
The shaft is very variable in contour, and it is extremely difficult to find two
fibulæ alike. It has a well-marked anterior border, which, beginning in front of
the head of the bone, divides in the lower third of the shaft, to enclose a triangular
subcutaneous surface continuous with the outer surface of the malleolus. This
border gives attachment to the anterior tibial fascia. The shaft on the outer side of
this border is usually deeply concave for a part of its extent, and gives origin to
the peroneus longus and brevis, and may be called the peroneal (or outer) surface.
Commencing at the head of the bone, in common with the anterior margin, and
then gently diverging from it, is the ridge to which the interosseous ligament is
attached. In the middle of the shaft the interosseous ridge is usually well marked,
and separated by 5 mm. from the anterior border. From the very narrow surface
limited by these ridges, the extensor longus digitorum, peroneus tertius, and
extensor longus hallucis arise. This is the extensor (or anterior) surface. The
remainder of the shaft is the flexor (or posterior) surface, and possesses three sub-
divisions. One in the middle of its posterior aspect (in the midst of which is the
orifice for the nutrient artery) gives origin to the flexor longus hallucis. This is
limited above by the oblique line for the fibular origin of the soleus. Between
these subdivisions and the interosseous ridge is the surface for the fibular origin
of the tibialis posticus.

THE FIBULA
169
The muscles arising from the fibula are:-
Soleus.
Tibialis posticus.
Peroneus longus.
Peroneus brevis.
The fibula affords insertion to the biceps.
Peroneus tertius."
Flexor longus hallucis.
Extensor longus digitorum.
Extensor proprius hallucis.
The following ligaments are connected with it :--
External lateral of the knee.
Anterior tibio-fibular.
Posterior tibio-fibular.
Interosseous membrane.
External lateral ligament of ankle.
Transverse.
Anterior tibio-fibular (inferior).
Posterior tibio-fibular.
External annular.
Anterior annular (vertical).
Blood-supply. The fibula receives the nutrient artery of its shaft from the
peroneal branch of the posterior tibial. The head is nourished by branches from
the inferior external articular branch of the popliteal artery, and the malleolus is
supplied mainly by the peroneal, anterior peroneal, and external malleolar arteries.
Development. The shaft of the fibula commences to ossify in the eighth week
of intra-uterine life. A nucleus appears for the lower in the second year, and one
in the fifth year for the upper extremity. The lower extremity fuses with the shaft
about twenty, but the upper one remains separate until the twenty-second year.
The human fibula differs from all others in the excessive length of its malleolus;
in no other vertebrate does this process descend below the level of the tibial malle-
olus. In the majority of mammals the tibial descends to a lower level than the
fibular malleolus. In the human embryo of the fourth month, the outer (fibular)
is very much smaller than the inner (tibial) malleolus. At the seventh month
they are equal in length; at birth, the fibular malleolus is the longer; and by the
second year it assumes its adult proportion. (Gegenbaur.)
The fibula is a vestigial bone in man, and survives mainly on account of the
excessive development of its malleolus. This accounts for the fact that the lower
epiphysis, though appearing first, unites with the shaft before the upper epiphysis.
In birds, the head of the bone is large, and enters into the formation of the
knee-joint, whilst the lower end atrophies.

THE FOOT
The bones comprised in the skeleton of the foot are arranged in three groups :-
tarsus, metatarsus, and phalanges.
The tarsus consists of seven bones:-The astragalus, os calcis or calcaneum,
scaphoid, cuboid, and three cuneiform bones.
THE ASTRAGALUS
This bone may, for descriptive purposes, be divided into a body, neck, and
head. The body is quadrilateral. Its upper aspect resembles a segment of the
wheel of a pulley; hence it is called the trochlear surface. It is broader in front
than behind, and articulates with the lower end of the tibia.

170
THE SKELETON
The inferior surface is occupied by an elongated concave facet for articulation
with the calcaneum.
The internal surface presents a pyriform facet, broad in front, and continuous
FIG. 168.-THE LEFT FOOT. (Dorsal surface.)
Tendo Achillis
Extensor brevis-
digitorum
Extensor longus
hallucis
CALCI
ASTRAGALUS
CAPHOID
CUBOID
Extensor brevis
digitorum
N
CUNEIFORM
MID.
CUNEIFORM
EX.
CUNEIFORM
Peroneus brevis
Peroneus tertius
Donsel interosse Muscles
2nd
3rd
4th
METATARSUS
IV
FIRST PHALANX
SECOND PHALANX
THIRD PHALANX
Extensor longus digitorum
with the trochlea: it articulates with the tibial malleolus. Below this facet, the
inner surface is rough for the attachment of the deep fibres of the deltoid ligament.

THE FOOT
171
The external surface is almost entirely occupied by a triangular concave facet,
broad above where it is continuous with the trochlea, for articulation with the
fibular malleolus.
FIG. 169.-THE LEFT FOOT. (Plantar surface.)
POSTERIOR SURFACE OF THE
CALCANEUM
Abductor minimi digiti
Abductor ossis metatarsi
quinti
Accessorius (outer head)
Flexor brevis hallucis
Abductor ossis metatarsi
quinti
Flexor brevis minimi
digiti
Abductor hallucis
Flexor brevis digitorum
Accessorius (inner head)
Tibialis posticus
Adductor hallucis
Third plantar
interosseous
Second plantar
interosseous
First plantar
interosseous
Flexor brevis minimi
digiti
Adductor brevis
minimi digiti
Third plantar
interosseous
Tibialis anticus
Peroneus longus
Second plantar
interosseous
First plantar
interosseous
Abductor hallucis
Flexor brevis hallucis
(inner portion)
Flexor brevis hallucis
(outer portion)
Adductor hallucis
Transversus pedis
Flexor brevis.
digitorum
Flexor longus
digitorum
Flexor longus hallucis
The posterior surface is little more than a ridge of bone traversed obliquely by
a deep groove, which receives the tendon of the flexor longus hallucis muscle.

172
THE SKELETON
Externally, this groove is limited by a prominent tubercle, which affords attachment
to the posterior fasciculus of the external lateral ligament of the ankle.
The neck is the constricted portion of the bone, and is continuous posteriorly
with the body of the astragalus. Superiorly, the neck is rough, and has numerous
foramina for blood-vessels. Inferiorly, it presents a deep groove, directed from
behind forwards and outwards. When the astragalus is articulated with the
calcaneum, this furrow is converted into a canal in which is lodged the calcaneo-
astragaloid (interosseous) ligament. The inner edge of this furrow is limited
by an articular facet, which runs forward to become continuous with the facet on
the head of the bone, and, like the articular surface of the sustentaculum tali of
the calcaneum on which it glides, is sometimes divided.
The head of the astragalus is furnished anteriorly with an ovoid facet, which
is received by the posterior surface of the scaphoid. On the inner and lower part,
at the spot where the sustentacular facet becomes confluent with that on the head,
there is a smaller facet separated by a ridge: this plays upon the calcaneo-scaphoid
or spring ligament.
FIG. 170.-THE LEFT ASTRAGALUS. (Plantar view.)
BODY-
GROOVE FOR THE FLEXOR LONGUS
HALLUCIS
FOR CALCANEUM
FOR THE SUSTENTACULUM TALI
NECK
HEAD
FOR THE CALCANEO-ASTRAGALOID
(OR THE SPRING) LIGAMENT,
FOR SCAPHOID
The os trigonum.-Occasionally the small portion of the astragalus posterior
to the trochlear surface containing the groove which lodges the flexor longus
hallucis tendon is separate from the rest of the astragalus, and is known as the
os trigonum, or secondary astragalus (fig. 171).
Articulations.-The astragalus articulates with four bones, the tibia, fibula,
scaphoid, and calcaneum; and presents seven articular facets; and when the facet
for the sustentaculum tali is divided, as is so often the case, the articular surfaces
are increased to eight. Sometimes it presents a facet on the outer margin of its
head for the cuboid, thus increasing the articular surfaces to nine.
Ligaments:-
Internal lateral ligament (deltoid).
External lateral ligament.
Astragalo-scaphoid.
Calcaneo-astragaloid (interosseous).
External calcaneo-astragaloid.
Posterior calcaneo-astragaloid.
Blood-supply. The astragalus is supplied by the dorsalis pedis artery and its
tarsal branch.
Ossification. The astragalus is ossified from one, occasionally from two, nuclei.
The principal centre for this bone appears in the middle of the cartilaginous astra-

THE ASTRAGALUS
173
galus at the seventh month of embryonic life. The additional centre is deposited
in the posterior portion of the bone, and forms that part of the astragalus which,
when it remains separate from the rest of the bone, is known as the os trigonum.
At birth, the astragalus presents some important peculiarities in the disposition of
the articular facet on the tibial side of its body, and in the obliquity of its neck.
If, in the adult astragalus, a line be drawn through the middle of the trochlear
surface parallel with its inner border, and a second line be drawn along the outer
side of the neck of the bone so as to intersect the first, the angle formed by these
two lines will express the obliquity of the neck of the bone. This in the adult varies
FIG. 171.-AN ASTRAGALUS WITH THE OS TRIGONUM.

OS TRIGONUM
greatly, but the average may be taken as 10°. In the foetus at birth the angle
averages 35°, whilst in a young orang it measures 45°. In the normal adult astra-
galus the articular surface on the tibial side is limited to the body of the bone.
In the foetal astragalus it extends for some distance on to the neck, and some-
times reaches almost as far forward as the scaphoid facet on the head of the bone.
This disposition of the inner malleolar facet is a characteristic feature of the
astragalus in the chimpanzee and the orang. It is related to the inverted position
of the foot which is found in the human embryo to near the period of birth, and is
of interest to the surgeon in connection with some varieties of club-foot. (Shattock
and Parker.)

THE CALCANEUM
The calcaneum, or os calcis, is the largest tarsal bone. It is cuboidal in shape,
and presents, for examination, six surfaces.
The superior surface has in its middle a large, oval, convex, articular facet
for the under aspect of the body of the astralagus; behind the facet, the bone is
rough and convex laterally. In front of the facet the bone presents a deep depres-
sion, the floor of which is rough for the attachment of ligaments, especially the
calcaneo-astragaloid, and the origin of the extensor brevis digitorum muscle; when
the calcaneum and astragalus are articulated, this portion of the bone forms a floor
to a cavity sometimes called the sinus pedis. Internally, this upper surface of the
bone presents a well-marked lip, the sustentaculum tali, furnished with an elon-
gated concave facet, occasionally divided into two, for articulation with the neck of
the astragalus.

174
THE SKELETON
The inferior surface is narrow and rough; it ends posteriorly in two tubercles:
the inner is the larger and broader, the outer is narrower but prominent. The
inner tubercle affords origin to the abductor hallucis, the flexor brevis digitorum,
and the abductor minimi digiti; the last muscle also arises from the inner
tubercle, and the ridge of bone connecting the tubercles. The outer tubercle affords
FIG. 172. THE LEFT CALCANEUM. (Dorsal view.)
INNER TUBERCLE-
INTEROSSEOUS GROOVE
FACET FOR ASTRAGALUS ON THE-
SUSTENTACULUM TALI
FOR ASTRAGALUS
PERONEAL TUBERCLE
attachment to the abductor ossis metatarsi quinti. The rough surface in front of
the tubercles gives attachment to the long plantar ligament (calcaneo-cuboid) and
the outer head of the flexor accessorius. Near its anterior end this surface forms
a rounded eminence, the anterior tubercle, from which (and the shallow groove in
front) the short plantar (calcaneo-cuboid) ligament arises.
The external surface is rough and slightly convex. Near the middle of this
FIG. 173.--THE CALCANEUM AT THE FIFTEENTH YEAR, SHOWING THE EPIPHYSIS.
APPEARS AT THE TENTH, AND UNITES AT THE SIXTEENTH YEAR
surface there is a small tubercle for the middle fasciculus of the external lateral
ligament of the ankle joint. Anteriorly, we notice the two shallow peroneal grooves,
separated by a tubercle, which is sometimes very prominent. The upper groove
is for the tendon of the peroneus brevis, and the lower lodges the tendon of the
peroneus longus.

THE CALCANEUM
175
The inner surface is deeply concave, the hollow being increased by the over-
hanging sustentaculum tali in front and above, and the prominent inner tubercle
posteriorly. The under aspect of the sustentaculum is deeply grooved for the
tendon of the flexor longus hallucis, whilst the hollow below receives the plantar
vessels and nerves. Its lower border serves for the attachment of the inner head
of the flexor accessorius. The margin of the sustentaculum has attached to it a
part of the deltoid ligament.
The anterior surface is a concave articular facet for the posterior surface of
the cuboid. Its outer and superior angle is somewhat prominent.
The posterior surface is roughly rounded, and at the lower part serves for the
attachment of the tendo Achillis. At its upper part it is smooth, and is in relation
with a bursa.
Articulations.
The calcaneum articulates with the cuboid, the astragalus, and
with the os trigonum when it exists as a separate element.
Muscles attached to the calcaneum:
Extensor brevis digitorum.
Abductor hallucis.
Flexor brevis digitorum.
Abductor minimi digiti.
Ligaments:--
Abductor ossis metatarsi quinti.
Accessorius.
Tendo Achillis.
Plantaris.
And a slip from the tibialis posticus.
Internal lateral of ankle.
External lateral of ankle.
Superior calcaneo-cuboid ligaments.
Inferior calcaneo-cuboid ligaments.
Internal annular.
External annular.
Anterior annular.

Calcaneo-astragaloid (interosseous).
External calcaneo-astragaloid.
Posterior calcaneo-astragaloid.
Superior calcaneo-scaphoid.
Inferior calcaneo-scaphoid.
Blood-supply. The calcaneum is a vascular bone, and derives its blood from
the posterior tibial, and the internal and external malleolar arteries.
Ossification. The primary nucleus for this bone is deposited in the sixth month
of embryonic life. In the tenth year a nucleus appears for the epiphysis at the
heel, and unites with the body of the bone at the sixteenth year. The inner and
outer tubercles are formed by the epiphysis.

THE CUBOID
This bone is situated on the outer side of the tarsus; its posterior surface
is reniform in shape and articular for the anterior face of the calcaneum. The
anterior surface is smaller, and divided by a low vertical ridge; the inner facet
FIG. 174. THE LEFT CUBOID. (Inner view.)
FOR EXTERNAL CUNEIFORM
FOR CALCANEUM
FOR FOURTH METATARSAL
GROOVE FOR TENDON OF THE
PERONEUS LONGUS
is for the base of the fourth, the outer facet receives the base of the fifth meta-
tarsal bone. The upper (dorsal) surface is rough and non-articular. The inferior
(plantar) surface is divided by a prominent ridge, which limits a deep furrow directed

176
THE SKELETON
from without forwards and inwards. This, the peroneal groove, lodges the
tendon of the peroneus longus.
The corner of the ridge on the narrow outer (fibular) border of the bone is
usually faceted for a sesamoid bone frequently found in the tendon of the peroneus
longus. The margin of the ridge and the surface of bone behind it afford attach-
ment to the long and short plantar (calcaneo-cuboid) ligaments. The flexor brevis
hallucis muscle has a small attachment to this part of the cuboid.
The internal surface presents near its middle and upper part an oval facet for
articulation with the external cuneiform bone; behind this, a second facet for the
scaphoid is frequently seen. Occasionally the two facets are confluent and form an
elliptical surface. The remainder of the internal surface is rough, and has strong
interosseous ligaments attached to it.
Jutting from the inferior internal angle of the posterior surface is a process of
bone (calcanean process of cuboid), which projects beneath the sustentaculum tali.
FIG. 175. THE LEFT CUBOID. (Inner view.)
FOR EXTERNAL CUNEIFORM
FOR CALCANEUM
FOR SCAPHOID
(OCCASIONAL)
GROOVE FOR TENDON OF
THE PERONEUS LONGUS
FOR FOURTH METATARSAL
This process occasionally terminates in a rounded facet, which plays on the head
of the astragalus external to the facet for the spring ligament.
Articulations.-The cuboid articulates with the calcaneum; the fourth and fifth
metatarsal bones, frequently with the scaphoid, and occasionally with the astragalus.
Muscles attached to the cuboid:-
Tibialis posticus.
Flexor brevis hallucis.
Ligaments:-
Superior calcaneo-cuboid.
Inferior calcaneo-cuboid.
Interosseous and the cubo-scaphoid ligaments.
Ossification. The cuboid is ossified from a single centre which appears a few
days after birth. Occasionally the nucleus is visible as a minute earthy spot in
the middle of the cartilage at birth.
THE SCAPHOID
The scaphoid (navicular) bone receives in the hollow of its posterior surface
the head of the astragalus. Anteriorly it is convex, and divided by two vertical
ridges into three facets, for the internal, middle, and external cuneiform bones.
Occasionally a fourth facet, extremely variable in size, is seen at the outer inferior
angle for the cuboid.
The upper (dorsal) surface is rough and broad; the inferior (plantar) surface is
nothing more than a ridge. The outer surface is rough for ligaments; whilst the
inner forms a large and prominent eminence, the scaphoid tuberosity, which affords
an important attachment for the tibialis posticus tendon.
Articulations. With the head of the astragalus, with the three cuneiform bones,
and frequently with the cuboid.
Muscle attached to the scaphoid.-The tibialis posticus.

THE SCAPHOID
177
Ligaments:-
Dorsal, plantar, and interosseous cubo-scaphoid.
Dorsal and plantar scapho-cuneiform.
External and inferior calcaneo-scaphoid.
Astragalo-scaphoid.
Ossification. The nucleus for the scaphoid appears in the course of the fourth
year. The tubercle of the scaphoid, into which the tibialis posticus acquires its
main insertion, occasionally develops separately, and sometimes remains distinct
from the rest of the bone.
FIG. 176. THE LEFT SCAPHOID. (Anterior view.)

FOR INTERNAL CUNEIFORM
INNER BORDER
TUBEROSITY
FOR MIDDLE CUNEIFORM
OUTER BORDER
FOR EXTERNAL CUNEIFORM
FIG. 177.-THE LEFT SCAPHOID, SHOWING A FACET FOR THE CUBOID.

FOR INTERNAL CUNEIFORM
TUBEROSITY
FOR MIDDLE CUNEIFORM
FOR EXTERNAL CUNEIFORM
FOR CUBOID

THE CUNEIFORM BONES
The cuneiform bones, three in number, are named from within outwards-
internal, middle, and external. They are wedge-shaped.
The INTERNAL CUNEIFORM is distinguished by its large size, and from the
fact that, when articulated, the base of the wedge is directed downwards, and the
sharp border upwards. The posterior surface is concave and pyriform for articu-
lating with the inner facet of the scaphoid. The anterior surface is a reniform
articular facet for the base of the first metatarsal. The internal surface is rough,
and presents an oblique groove for the tendon of the tibialis anticus: this groove
is limited inferiorly by an oval facet into which a portion of the tendon is inserted.
The external surface is concave and rough, except along the posterior and superior
borders. Near the anterior extremity of the superior border there exists a distinct
circular facet for the inner side of the base of the second metatarsal. In front of
the facet a few fibres of the first dorsal interosseous muscle arise. The remaining
sinuous articular facet is for the inner surface of the middle cuneiform.
Articulations. With the scaphoid, middle cuneiform, and the first and second
metatarsals.
Muscles.-Tibialis anticus and posticus, the peroneus longus, and first dorsal
interosseous.
Ossification.-A single nucleus, which appears in the course of the third year.
The MIDDLE CUNEIFORM, the smallest of the three, has its base directed
upwards and the sharp border downwards. The posterior concave surface is
N

178
THE SKELETON
articular for the middle facet of the scaphoid. The anterior, somewhat narrower
than the posterior surface, articulates with the base of the second metatarsal. The
internal surface has a facet extending along its upper and posterior borders for the
internal cuneiform. The external surface has a facet along the posterior border,
and occasionally one at the anterior inferior angle for the external cuneiform.
FIG. 178. THE LEFT INTERNAL CUNEIFORM. (Internal surface.)
FOR FIRST METATARSAL
FACET FOR THE TENDON OF THE
TIBIALIS ANTICUS
FIG. 179.-THE LEFT INTERNAL CUNEIFORM. (External surface.)
FOR SECOND METATARSAL-
FOR MIDDLE CUNEIFORM
FOR SCAPHOID
FIG. 180.-THE LEFT MIDDLE CUNEIFORM. (Internal surface.)
FOR INTERNAL CUNEIFORM
FOR SECOND METATARSAL
FIG. 181. THE LEFT MIDDLE CUNEIFORM. (External surface.)
OCCASIONAL FACET FOR EXTERNAL CUNEIFORM-
FOR EXTERNAL CUNEIFORM
FOR SCAPHOID
---
Articulations. With the internal and external cuneiform bones, the scaphoid
and the second metatarsal.
Ossification. A single nucleus appears in the fourth year.
The EXTERNAL CUNEIFORM has its base directed upwards, and its narrow
border downwards. The posterior surface is faceted for the scaphoid; and the

THE METATARSUS
179
anterior, triangular in shape, articulates with the base of the third metatarsal. The
internal surface has a large facet, extending along the posterior border, for the
middle cuneiform; and on the anterior border, a narrow irregular facet for the outer
border of the base of the second metatarsal; and occasionally a small facet at the
anterior inferior angle for the middle cuneiform. The outer surface has a broad
distinctive facet, near its posterior superior angle, for the cuboid; and at the
anterior superior angle there is usually a facet for the inner side of the base of the
fourth metatarsal.
FIG. 182.-THE LEFT EXTERNAL CUNEIFORM. (Internal surface.)

FOR MIDDLE CUNEIFORM
FOR SCAPHOID
FOR SECOND METATARSAL. THE CIRCULAR
FACET AT THE INFERIOR ANGLE IS FOR
THE MIDDLE CUNEIFORM
FIG. 183. THE LEFT EXTERNAL CUNEIFORM. (External surface.)

FOR FOURTH METATARSAL
FOR THIRD METATARSAL
FOR CUBOID
Articulations. With the middle cuneiform, the scaphoid, the cuboid, and the
second, third and fourth metatarsals.
Muscles. The flexor brevis hallucis and a slip from the tibialis posticus.
Ossification. A single nucleus appears in the course of the first year.
The three cuneiform bones rest posteriorly against the scaphoid; and as they
are of unequal length, the middle being the smallest, it follows that when the
bones are placed in their natural positions a deep gap or recess is formed in front.
Into this recess the base of the second metatarsal is received, thus explaining the
small facets at the anterior superior angles of the internal and external cuneiforms.

THE METATARSUS
The metatarsus consists of five bones, numbered one to five, beginning at the
hallux. Each metatarsal presents a proximal portion termed the base, and a distal
end or head. The shaft of each bone, with the exception of the first, is prismatic;
the base of the prism is directed upwards, and the narrow edge downwards. The
shaft tapers gradually from the base to the head and is slightly bowed, the
concavity being on the plantar aspect.
The base is prismatic: its terminal surface is faceted for articulation with the
tarsus, and the adjacent borders of the base present small facets, in most cases for
adjacent metatarsals.
The head is semicircular, forming a convex articular surface for the base of the
first phalanx. The compressed sides of the head present near their centres a
depression surmounted by a prominent tubercle. The plantar surface is deeply
N 2

180
THE SKELETON
grooved for the passage of flexor tendons. To the sides of the head the lateral
ligaments of the metatarso-phalangeal joints are attached.
The FIRST METATARSAL is the most modified; it is shorter, but much thicker
than its fellows. The base presents a reniform, slightly concave facet for the
FIG. 184. THE FIRST (LEFT) METATARSAL.

TIBIAL
OR
INNER SIDE
TIBIAL
OR
INNER SIDE
AN OCCASIONAL FACET FOR THE,
FIRST METATARSAL
INTERNAL CUNEIFORM
FACET FOR INTERNAL
CUNEIFORM
FIG. 185.-THE SECOND (LEFT) METATARSAL.
FACET FOR MIDDLE
CUNEIFORM
FIBULAR
OR
OUTER SIDE
FOR PERONEUS LONGUS
FACET FOR SECOND
METATARSAL
(OCCASIONAL)

FIBULAR
OR
OUTER SIDE
hasil to Ing
FACETS FOR THIRD METATARSAL
FACETS FOR EXTERNAL
CUNEIFORM

internal cuneiform bone. On the outer (fibular) side of the base, near its lower
angle, there is a tubercle into which the peroneus longus is inserted. A little above
this, there is frequently a shallow but easily recognised facet where it comes into
contact with the base of the second metatarsal.

THE METATARSUS
181
The head of the bone has two deep grooves on the plantar surface for the
sesamoids developed in the flexor brevis hallucis muscle.
Muscles. Peroneus longus; tibialis anticus; first dorsal interosseous.
Blood-supply. The nutrient vessel enters the shaft on the fibular side, and is
directed towards the head of the bone.
FIG. 186. THE THIRD (LEFT) METATARSAL.

FACETS FOR SECOND METATARSAL
TIBIAL
OR
INNER SIDE
FACETS FOR SECOND METATARSAL
FACET FOR EX-
TERNAL CUNEIFORM
Tylaqub-boola
FIBULAR
OR
OUTER SIDE
FACET FOR FOURTH METATARSAL
FIG. 187.-THE FOURTH (LEFT) METATARSAL.
FACET FOR
FOURTH METATARSAL
TIBIAL
OR
INNER SIDE
FACET FOR FOURTH METATARSAL
FACET FOR EXTERNAL CUNEIFORM
CUBOID FACET
FIBULAR
OR
OUTER SIDE
FACET FOR FIFTH METATARSAL
The SECOND METATARSAL is the longest of the series. Its base is prolonged
backwards to occupy the space between the internal and external cuneiform bones;
this leads to the formation of a small facet at the superior angle on the tibial side
where it articulates with the internal cuneiform. It occasionally presents a small

182
THE SKELETON
facet for the first metatarsal. The outer (fibular) side of the base has two facets,
each subdivided in well-marked bones. The dorsal facet is long and narrow; the
posterior section articulates with the external cuneiform; the anterior is for the
third metatarsal. The lower facet is somewhat circular: its posterior section is for
the external cuneiform, the anterior for the third metatarsal. The terminal facet on
the base is for the middle cuneiform: thus the second metatarsal articulates with
three cuneiform bones.
Muscles.-Adductor hallucis; first and second dorsal interosseous.
Blood-supply. The nutrient artery enters on the fibular side near the middle
of the shaft, and is directed towards the base of the bone.
The THIRD METATARSAL articulates by its base with the external cuneiform.
It has on the inner (tibial) side two facets: one below the other for the second
metatarsal, and a large facet on the fibular side for the fourth metatarsal.
FIG. 188.-THE FIFTH (LEFT) METATARSAL.
TIBIAL
OR
INNER SIDE
FOURTH METATARSAL
CUBOID FACET
CUBOID FACET
FIBULAR
OR
OUTER SIDE
TUBEROSITY
Muscles.-Adductor hallucis; first plantar; second and third dorsal inter-
osseous.
Blood-supply. The nutrient artery enters on the inner (tibial) side of the shaft
near its middle: it is directed towards the base.
The FOURTH METATARSAL has a somewhat quadrilateral terminal facet for
the cuboid bone. On its inner (tibial) side it has a large facet for the third
metatarsal: the posterior part of this is occasionally marked off for the external
cuneiform, but this is far from constant. When this cuneiform facet is present, the
facet extends to the base of the bone. When absent, the surface is rough for
ligament. The outer (fibular) side has a single facet for the fifth metatarsal.
Muscles. Adductor hallucis; second plantar interosseous; third and fourth
dorsal interosseous.
Blood-supply. The nutrient artery of the shaft enters on the inner (tibial) side
and runs towards the base.
The FIFTH METATARSAL has on the fibular side of its base a large nipple-
shaped tuberosity, to which the tendon of the peroneus brevis is inserted. Its
oblique terminal facet articulates with the cuboid, and on the tibial side it has a

THE METATARSUS
183
large facet for the fourth metatarsal.
The plantar aspect of the base has a
shallow groove which lodges the abductor minimi digiti.
Muscles:-
Third plantar interosseous.
Peroneus tertius.
Fourth dorsal interosseous.
Peroneus brevis.
Abductor ossis metatarsi quinti.
Flexor brevis minimi digiti.
Blood-supply. The nutrient artery enters on the tibial side of the shaft and
runs towards the base.
Ossification.-Each metatarsal ossifies from two centres. The primary nucleus
for the diaphysis appears in the eighth week of embryonic life in the middle of the
cartilaginous metatarsal. At birth, each extremity is represented by cartilage, and
that at the proximal end is ossified by extension from the primary nucleus, except
in the case of the first metatarsal. For this, a nucleus appears in the third year.
The distal ends of the four outer metatarsals are ossified by secondary nuclei
which make their appearance about the third year. Very frequently an epiphysis
is found at the distal end of the first metatarsal as well as at its base. The shafts
and epiphyses consolidate at the twentieth year. The sesamoids belonging to the
flexor brevis hallucis begin to ossify about the fifth year.
THE PHALANGES
There are fourteen phalanges to each foot. The hallux has two, and the
remaining toes three each. They are usually distinguished as first, second, and
third. The last are sometimes called the ungual phalanges, because they support
the nail.
FIG. 189.-THE PHALANGES OF THE MIDDLE TOE.
THIRD,
TERMINAL OR
UNGUAL
PHALANX

SECOND
PHALANX
FIRST
PHALANX
-10
The phalanges of the first row have narrow laterally compressed shafts, rounded
on the dorsal and concave on the plantar aspects. The bases have deep glenoid
fosse for the convex heads of the metatarsals with which they articulate; whilst
the heads have trochlear surfaces for the bases of the second phalanges.
The phalanges of the second row are stunted, insignificant bones. Their

184
THE SKELETON
shafts are flatter than those of the first row, besides being much shorter. The
bases have two depressions, separated by a vertical ridge. The heads present
trochlear surfaces for the ungual phalanges.
The third, terminal, or ungual phalanges are easily recognised. The bases
articulate with the second phalanges; the shafts are expanded to support the
nails, and their palmar surfaces are rough where they come into relation with the
pulp of the digit.
Vimura hoold
FIG. 190.-A LONGITUDINAL SECTION OF THE BONES OF THE LOWER LIMB AT BIRTH.
THE CENTRE FOR THE LOWER EX-
TREMITY OF THE FEMUR APPEARS
EARLY IN THE NINTH MONTH
THE CENTRE FOR THE UPPER END OF
THE TIBIA APPEARS ABOUT A WEEK
BEFORE BIRTH
CARTILAGE FOR THE PATELLA, APPEARS ABOUT
THE FOURTH MONTH OF INTRA-UTERINE LIFE
THE CENTRE FOR THE ASTRAGALUS.
APPEARS IN THE SEVENTH MONTH
THE CENTRE FOR THE CALCANEUM
APPEARS IN THE SIXTH MONTH
elady
THE CENTRE FOR THE SCAPHOID APPEARS IN THE FOURTH
YEAR
FOR THE INTERNAL CUNEIFORM APPEARS IN THE THIRD
YEAR
METATARSAL OF HALLUX
FIRST PHALANX OF HALLUX
SECOND PHALANX OF HALLUX
The first phalanx of the hallux gives insertion to the following muscles :-Flexor
brevis hallucis; abductor hallucis; transversus pedis; adductor hallucis; extensor
brevis digitorum.
The first phalanx of second toe: The first and second dorsal interosseous.
The first phalanx of third toe: Third dorsal interosseous; first plantar inter-
osseous.
The first phalanx of fourth toe: Second plantar interosseous; fourth dorsal
interosseous.
The first phalanx of fifth toe: Third plantar interosseous; flexor brevis minimi
digiti; and adductor minimi digiti.
The second phalanx of hallux: Flexor longus hallucis; extensor longus hallucis.
The second phalanges of the remaining toes: Extensor longus digitorum;
flexor brevis digitorum.
The third phalanges: Flexor longus digitorum; extensor longus digitorum.
Ossification.-Like the phalanges of the fingers, those of the toes ossify from a
primary and a secondary nucleus. The centres for the shaft appear during the

THE PHALANGES
185
eighth and tenth weeks of embryonic life; the secondary centres' appear as thin
scale-like epiphyses at the proximal ends between the fourth and eighth years.
They consolidate earlier than the corresponding epiphyses in the fingers.
The ungual phalanges, like those of the fingers, ossify from the distal
extremity.
FIG. 191.-THE SECONDARY OSSIFIC CENTRES OF THE FOOT.

THE CENTRE FOR THE EPIPHYSIS FOR
THE CALCANEUM APPEARS AT THE
TENTH YEAR; CONSOLIDATES AT THE
SIXTEENTH YEAR
2ZOITAI
THE CENTRE FOR THE EPIPHYSIS FOR-
THE METATARSAL OF THE HALLUX
APPEARS AT THE THIRD YEAR; CON-
SOLIDATES AT THE TWENTIETH YEAR
THE CENTRES FOR THE BASE OF THE
TERMINAL PHALANGES APPEAR AT
SIXTH YEAR; AND CONSOLIDATE AT
THE EIGHTEENTH YEAR
GHT
T
THE CENTRES FOR THE HEADS OF THE METATARSALS
APPEAR AT THE THIRD YEAR; AND CONSOLIDATE AT THE TWENTIETH YEAR
The average dates of ossification of the bones of the foot :-
Calcaneum
Epiphysis
Astragalus
Cuboid
Scaphoid
Internal cuneiform
Middle cuneiform
External cuneiform
Metatarsals
Epiphyses.
Phalanges
Epiphyses.
Sixth month.
Tenth year.
Seventh month.
At, or near, the ninth month.
Fourth or fifth year.
Third year.
Fourth year.
First year.
Eighth to ninth week.
Third year; consolidate at the
twentieth year.
Eighth to tenth week.
Fourth to eighth year; consolidate
about the eighteenth year.

SECTION II.
THE ARTICULATIONS
BY HENRY MORRIS, M.A., M.B.LOND., F.R.C.S.ENG.
SURGEON TO AND LECTURER ON SURGERY, FORMERLY LECTURER ON ANATOMY AT THE MIDDLESEX HOSPITAL;
LATE EXAMINER IN ANATOMY IN THE UNIVERSITY OF DURHAM; FOR THE CONJOINT BOARD OF THE ROYAL
COLLEGES OF PHYSICIANS AND SURGEONS; AND FOR THE FELLOWSHIP OF THE ROYAL COLLEGE OF SURGEONS.
THE
HE section devoted to the Articulations or Joints deals with the union of
the various and dissimilar parts of the human skeleton. The following
structures enter into the formation of joints.
Bones constitute the basis of most joints. The articular ends are expanded,
and are composed of cancellous tissue, surrounded by a dense and strong shell of.
compact tissue. This shell has no Haversian canals (the vessels of the cancellous
tissue turn back and do not perforate it), or large lacunæ, and no canaliculi, and
are thus well adapted to bear pressure. The long bones articulate by their ends,
the flat by their edges, and the short at various parts on their surfaces.
The cartilage which covers the articular ends of the bones is called articular,
and is of the hyaline variety. It is firmly implanted on the bone by one
surface, while the other is smooth, polished, and free, thus reducing friction to a
minimum, while its slight elasticity tends to break jars. It ends abruptly at the
edge of the articulation, and is thickest over the areas of greatest pressure.
Another form of cartilage, the white fibrous, is also found in joints :-
(i) As interarticular cartilage in diarthrodial joints-viz., the knee, temporo-
mandibular, sterno-clavicular, radio-carpal, and occasionally in the acromio-
clavicular. It is interposed between the ends of the bones, partially or completely
dividing the synovial cavity into two. It serves to adjust dissimilar bony surfaces,
adding to the security of, while it increases the extent of motion at, the joint, and
also acts as a buffer to break shocks.
(ii) As circumferential or marginal fibro-cartilages, they serve to deepen the
sockets for the reception of the heads of bones-e.g. the glenoid and cotyloid
ligaments of the shoulder and knee. Another form of marginal plate is seen in
the glenoid ligaments of the fingers and toes, which deepen the articulations of
the phalanges and adds to their security.
(iii) As connecting fibro-cartilage. The more pliant and elastic is the more
cellular form, and is found in the intervertebral discs; while the less yielding and
more fibrous form is seen in the sacro-iliac and pubic articulations, where there is


little or no movement.
The ligaments which bind the bones together are strong bands of white fibrous
tissue, forming a more or less perfect capsule, round the articulation. They are
pliant but inextensile, varying in shape, strength, and thickness according to the

VARIOUS ARTICULATIONS
187
kind of articulation into which they enter. They are closely connected with the
periosteum of the bones they unite. In some cases-as the ligamenta subflava
which unite parts not in contact-they are formed of yellow elastic tissue.
The synovial membrane, lines the interior of the fibrous ligaments, thus
excluding them, as well as the cushions or pads of fatty tissue situate within
and the tendons which perforate the fibrous capsule, from the articular cavity.
It is a thin delicate membrane, frequently forming folds and fringes which
project into the cavity of the joint; or, as in the knee, stretches across the cavity,
forming a so-called synovial ligament. In these folds are often pads of fatty tissue,
which fill up interstices, and form soft cushions between the contiguous bones.
Sometimes these fringes become villous and pedunculated, and cause pain in move-
ments of the joints. They contain fibro-fatty tissue, with an isolated cartilage cell
or two. The synovial membrane is well supplied with blood, especially near the
margins of the articular cartilages and in the fringes. It secretes a thick glairy
fluid like white of egg, called synovia, which lubricates the joint. Another variety
of synovial membrane is seen in the bursæ, which are interposed between various
moving surfaces. In some instances bursæ in the neighbourhood of a joint may
communicate with the synovial cavity of that joint.
THE VARIOUS KINDS OF ARTICULATIONS
There are three chief varieties of joints-viz., synarthrodial, or immovable ;
amphiarthrodial, or yielding; and diarthrodial, or movable joints.
Synarthrosis is the term applied to all immovable joints in which the apposed
surfaces or edges of the bones are in direct contact, as in the face bones, except
the mandible, and all those of the skull; or where bone and cartilage are in
immediate union, as in the case of the first rib and the sternum, and the costal
cartilages and the ribs. The unions of the bones of the skull and face are usually
called sutures, of which there are three chief varieties:-
True sutures, where the edges of bones are firmly implanted into one another
by means of projecting processes, as in the sagittal, lambdoid, and coronal sutures.
False sutures, where the rough edges of the bones are in simple contact without
interlocking, as in the intermaxillary suture; or where they overlap one another, as
in the squamous suture.
Grooved sutures, where the edge or plate of one bone is received into a cor-
responding groove in the other, as in the rostrum of the sphenoid and vomer, or
vomer and palatine processes of the maxillæ, and the horizontal plates of the palate
bones.
Amphiarthrosis is the term applied to mixed joints which permit of slight
movements, the opposed bony surfaces being firmly united by a plate or disc of
fibro-cartilage. There is sometimes a partial synovial membrane. Examples are
seen in the spine, sacro-iliac, and pubic joints.
Diarthrosis is the term applied to all movable joints in which the bones have
smooth cartilage-covered surfaces, lubricated by synovia, and bound together by
more or less perfect capsules.
This class is subdivided into the following
varieties:-
1. Arthrodia.-A simple gliding joint formed by the apposition of two plane, or
nearly plane, surfaces, which allow motion in one or more directions. The articular
processes of the vertebræ, the joints of the carpus and tarsus, carpo-metacarpal,
tarso-metatarsal, and intermetacarpal and intermetatarsal joints are good examples.


188
THE ARTICULATIONS
2. Ginglymus, or hinge-joint, where the ends of the bones are so adapted to
each other as to allow motion in two directions, namely flexion and extension; the
most perfect of them are the elbow and ankle. The knee has some gliding and
rotatory motion, and is not a perfect hinge-joint, but ginglymo-arthrodial.
3. Enarthrodia, or ball-and-socket joint, where the enlarged head of one bone
is received into a socket adapted to it on the other, as in the hip and shoulder
joints. They are the most movable of all the joints, combining movements in all
directions with axial rotation.
4. Trochoides, or pulley joints: this term is applied where either a pivot revolves
in a ring, as in the superior radio-ulnar; or the ring revolves about a pivot, as in
the central atlanto-axoidean joint.
TABLE OF THE VARIOUS CLASSES OF JOINTS
Class.
I. Synarthrosis
(a) True sutures
(b) False sutures
(c) Grooved sutures
II. Amphiarthrosis.
III. Diarthrosis
(a) Arthrodia
(b) Ginglymus.
(c) Ginglymo-arthrodia
(d) Enarthrodia
(e) Trochoides, diarthrosis)
rotatoria, or lateral
ginglymus.
Examples.
Lambdoid, sagittal, coronal.
Internasal. Intermaxillary. Costo-chon-
dral.
Vomer and rostrum of sphenoid.
Bodies of vertebræ. Symphysis pubis,
sacro-iliac, sacro-coccygeal.
Carpal, tarsal, carpo-metacarpal, tarso-
metatarsal, intermetacarpal, and inter-
metatarsal. Costo-transverse. Inter-
chondral (i.e. between costal cartilages).
Sterno-clavicular, acromio - clavicular.
Tibio-fibular. Lateral atlanto-axoidean;
and the joints between articular processes
of vertebræ.
Elbow, ankle, wrist (double ginglymus).
Metacarpo- and metatarso-phalangeal.
Interphalangeal.
Temporo-mandibular. Occipito-atlantal.
Knee.
Shoulder. Hip.
Central atlanto-axoidean, Superior and
inferior radio-ulnar.
THE VARIOUS MOVEMENTS OF JOINTS
The movements which may take place at a joint are either gliding, angular,
rotatory, or circumductory.
The gliding motion is the simplest, and is common to all diarthrodial joints: it
consists of a simple sliding of the apposed surfaces of the bones upon one another,
without angular or rotatory motion. It is the only kind of motion permitted in the
carpal and tarsal joints, and in those between the articular processes of the vertebræ.
The angular motion is more elaborate, and increases or diminishes the angle
between different parts. There are four varieties, viz.: flexion and extension, which

MOVEMENTS OF JOINTS
189
bend or straighten the various joints, and take place in a forward and backward
direction (in a perfect hinge-joint this is the only motion permitted); and adduc-
tion and abduction, which, except in the case of the fingers and toes, signifies an
approach to, or deviation from, the centre line of the body. In the case of the hand,
the line to or from which adduction and abduction are made is drawn through
the middle finger, while in the foot it is through the second toe.
Rotation is the revolution of a bone about its own axis without much change
of position. It is only seen in enarthrodial and trochoidal joints. The knee
permits of slight rotation, also, in certain positions, which is a distinctive feature
of this articulation.
Circumduction is the movement compounded of the four angular movements
in quick succession, by which the moving bone describes a cone, the proximal end
of the bone forming the apex, while the distal end describes the base of the cone.
It is seen in the hip and shoulder, as well as in the carpo-metacarpal joint of the
thumb, which thus approximates to the ball-and-socket joint.
In some situations where a variety of motion is required, strength, security, and
celerity are obtained by the combination of two or more joints, each allowing a
different class of action, as in the case of the wrist, the ankle, and the head with the
spine. Many of the long muscles, which pass over two or more joints, act on all, so
tending to co-ordinate their movements and enabling them to be produced with the
least expenditure of power. Muscles also act as elastic ligaments to the joints; and
when acting as such, are diffusers and combiners, not producers of movement;
the short muscles producing the movement, the long diffusing it, and thus allowing
the short muscles to act on more than one joint.
Muscles are so disposed at their attachments near the joints as never to strain
the ligaments by tending to pull the bones apart, but, on the contrary, they add to
the security of the joint by bracing the bones firmly together during their action.
The articulations may be divided for convenience of description into those : 1. of
the SKULL; 2. of the TRUNK; 3. of the UPPER LIMB; and 4. of the LOWER LIMB.

1. THE ARTICULATIONS OF THE SKULL
The articulations of the skull comprise (1) the temporo-mandibular; and
(2) those between the skull and first two vertebræ : namely (a) between the occiput
and atlas; (b) between the atlas and axis; and (c) the ligaments which connect
the occiput and axis.
The union of the atlas and axis is described in this section because, firstly,
there is often a direct communication between the synovial cavity of the transverse
axoidean and the occipito-atlantal joints; secondly, the rotatory movements of the
head take place around the odontoid process; and, thirdly, important ligaments
from the odontoid process pass over the atlas to the occiput.
(1) THE TEMPORO-MANDIBULAR ARTICULATION
Class.-Diarthrosis.
Subdivision.-Ginglymo-Arthrodia.
The parts entering into the formation of this joint are:-the anterior portion of
the glenoid fossa and glenoid ridge (eminentia articularis) of the temporal bone above,
and the condyle of the lower jaw below. Both are covered with articular cartilage,

190
THE ARTICULATIONS
which is also extended over the front of the glenoid ridge to facilitate the play of
the interarticular cartilage. The ligaments which unite the bones are:-
1. Capsular.
2. Interarticular fibro-cartilage.
3. Spheno-mandibular.
4. Stylo-mandibular.
The capsular ligament is often described as consisting of four portions, which
are, however, continuous with one another around the articulation.
1. The anterior portion consists of a few stray fibres connected with the anterior
margin of the fibro-cartilage, and attached below to the anterior edge of the condyle,
and above to the front of the glenoid ridge. Some fibres of insertion of the external
pterygoid pass between them to be inserted into the margin of the fibro-cartilage.
2. The posterior portion is attached above, just in front of the Glaserian fissure,
and is inserted into the back of the jaw just below its neck.
3. The external portion or external lateral ligament (fig. 192) is the strongest
part of the capsule. It is broader above, where it is attached to the lower edge
of the zygoma in nearly its whole length, as well as to the tubercle at the point
where the two roots of the zygoma meet. It is inclined downwards and backwards,
to be inserted into the outer side of the neck of the condyle. Its fibres diminish
in obliquity and strength from before backwards, those coming from the tubercle
being short and nearly straight.
4. The internal portion or short internal lateral ligament (fig. 193) consists
of well-defined fibres, having a broad attachment, above to the outer side of the alar
spine of the sphenoid and inner edge of the glenoid fossa; and below, a narrow
insertion to the inner side of the neck of the condyle. Fatty and cellular tissue
separate it from the spheno-mandibular ligament which is internal to it.
The interarticular cartilage (fig. 194) is an oval plate interposed between
and adapted to the two articular surfaces. It is thinner at the centre than at the
circumference, and is thicker behind where it covers the thin bone at the bottom
of the glenoid fossa which separates it from the dura mater, than in front where
it covers the glenoid ridge. Its inferior surface is concave and fits on to the
condyle of the lower jaw; while its superior surface is concavo-convex from before
backwards, and is in contact with the articular surface of the temporal bone. It
divides the joint into two separate synovial cavities, but is occasionally perforated
in the centre, and thus allows them to communicate. It is connected to the
capsular ligament at the margins, and has some fibres of the external pterygoid
muscle inserted into its anterior margin.
There are usually two synovial membranes (fig. 194), the superior being the
larger and looser, passing down from the margin of the articular surface above, to
the upper surface of the interarticular cartilage below; the lower and smaller one
passes from the interarticular cartilage above to the condyle of the jaw below,
extending somewhat further down behind than in front. When the interarticular
cartilage is perforated, the two sacs communicate.
The spheno-mandibular ligament (long internal lateral) (fig. 193) is a thin,
loose band, situated some little distance from the joint. It is attached above to
the alar spine of the sphenoid and contiguous part of the temporal bone, and is
inserted into the mandibular spine of the lower jaw. It covers the upper end of
the mylo-hyoid groove, and is here pierced by the mylo-hyoid nerve. Its origin
is a little internal to, and behind, but close to the origin of the short internal
lateral ligament. It is separated from the joint and ramus of the jaw by the
external pterygoid muscle, internal maxillary artery and vein, the mandibular
nerve and artery, and the middle meningeal artery. It is really the fibrous
remnant of a part of the mandibular (Meckelian) bar.
The stylo-mandibular ligament (stylo-maxillary) (figs. 192 and 193) is a process

TEMPORO-MANDIBULAR
191
of the deep cervical fascia extending from near the tip of the styloid process to
the angle and posterior border of the ramus of the jaw, between the masseter and
internal pterygoid muscles. It separates the parotid from the submaxillary gland,
and gives origin to some fibres of the stylo-glossus muscle.
FIG. 192.-EXTERNAL VIEW OF TEMPORO-MANDIBULAR JOINT.

External portion
of capsule
Stylo-mandibular ligament
FIG. 193.-INTERNAL VIEW OF TEMPORO-MANDIBULAR JOINT.

Internal portion
of capsule
Spheno-mandibular
ligament
Stylo-mandibular
ligament
Stylo-hyoid
ligament
The arterial supply is from derived the temporal, middle meningeal, and ascend-
ing pharyngeal by its branches to the Eustachian tube.
The nerves are derived from the masseteric and auriculo-temporal.
Movements. The chief movement of this joint is of (i) a ginglymoid or hinge
character, accompanied by a slight gliding action, as in opening or shutting the

192
THE ARTICULATIONS
mouth. In the opening movement the condyle turns like a hinge on the fibro-
cartilage, while at the same time the fibro-cartilage, together with the condyle, glides
forward so as to rise upon the eminentia articularis; the fibro-cartilage reaching as
far as the anterior edge of the eminence, which is coated with articular cartilage to
receive it; but the condyle never reaches quite so far as the summit of the eminence.
Should the condyle, however, by excessive movement (as in a convulsive yawn), glide
over the summit, it slips into the zygomatic fossa, the mandible is dislocated, and
the posterior portion of the capsule is torn. In the shutting movement the condyle
revolves back again, and the fibro-cartilage glides back, carrying the condyle with
it. This combination of the hinge and gliding motions gives a tearing as well as
a cutting action to the incisor teeth, without any extra muscular exertion.
There is (ii) a horizontal gliding action in an antero-posterior direction, by
which the lower teeth are thrust forwards and drawn back again: this takes place
almost entirely in the upper compartment, because of the closer connection of the
FIG. 194.-VERTICAL SECTION THROUGH THE CONDYLE OF JAW TO SHOW THE TWO
SYNOVIAL SACS AND THE INTERARTICULAR FIBRO-CARTILAGE.
Interarticular fibro-
cartilage
SECTION THROUGH CONDYLE
Posterior portion of
capsule
Spheno-mandibular ligament
Stylo-mandibular ligament
fibro-cartilage to the condyle than to the squamosal bone, and also because of the
insertion of the external pterygoid into both bone and cartilage. In these two sets
of movements the joints of both sides are simultaneously and similarly engaged.
The third form of movement is called (iii) the oblique rotatory, and is that by
which the grinding and chewing actions are performed. It consists in a rotation
of the condyle about the vertical axis of its neck in the lower compartment, while
the cartilage glides obliquely forwards and inwards on one side, and backwards
and inwards on the other, upon the articular surface of the squamosal bones,
each side acting alternately. If the symphysis be simply moved from the centre
to one side and back again, and not from side to side as in grinding, the condyle
of that side moves round the vertical axis of its neck, and the opposite condyle
and cartilage glide forwards and inwards upon the glenoid fossa. But in the
ordinary grinding movement, one condyle advances and the other recedes, and
then the first recedes while the other advances, slight rotation taking place in each
joint meanwhile.
ATLAS WITH OCCIPUT
193
(2) THE LIGAMENTS AND JOINTS BETWEEN THE SKULL AND
SPINAL COLUMN, AND BETWEEN THE ATLAS AND AXIS
(a) THE ARTICULATION OF THE ATLAS WITH THE OCCIPUT
Class.-Diarthrosis.
Subdivision.-Ginglymo-Arthrodia.
This articulation consists of a pair of joints symmetrically situated on either
side of the middle line. The parts entering into their formation are the cup-
shaped superior articular processes of the atlas, and the condyles of the occipital
bone. They are united by the following ligaments :-
1. Anterior occipito-atlantal.
2. Posterior occipito-atlantal
3. Two capsular.
4. Two anterior oblique.
The anterior occipito-atlantal ligament (fig. 195) is less than an inch (about
2 cm.) wide, and is composed of densely woven fibres, most of which radiate
slightly outwards as they ascend from the front surface and upper margin of the
anterior arch of the atlas, to the anterior border of the foramen magnum; it is
continuous laterally with the capsular ligaments, the fibres of which overlap its
edges, and take an opposite direction inwards and upwards. The central fibres take
a vertical course as they ascend from the anterior tubercle of the atlas to the
pharyngeal tubercle on the occipital bone; they are thicker than the lateral fibres,
and are continuous below with the superficial part of the anterior atlanto-axoidean
ligament, and through it with the anterior common ligament of the vertebral
column. It is in relation, in front, with the recti capitis antici minores; and
behind, with the central odontoid or suspensory ligament.
The posterior occipito-atlantal ligament (fig. 196) is broader, more membranous,
and not so strong as the anterior. It extends from the posterior surface and
upper border of the posterior arch of the atlas to the posterior margin of the
foramen magnum from condyle to condyle; being incomplete on either side for the
passage of the vertebral artery into, and suboccipital nerve out of, the canal.
It is somewhat thickened in the middle line by fibres, which pass from the posterior
tubercle of the atlas to the lower end of the occipital crest. It is not tightly
stretched between the bones, nor does it limit their movements; it corresponds
with the position of the ligamenta subflava, but has no elastic tissue in its
composition. It is in relation in front with the dura mater, which is firmly
attached to it; and behind with the recti capitis postici minores, and enters into
the floor of the suboccipital triangle.
The capsular ligaments (figs. 195, 196) are very distinct and strongly marked,
except on the inner side, where they are thin and formed only of short membranous
fibres. They are lax, and do not add much to the security of the joint. In front, the
capsule descends upon the atlas, to be attached, some distance below the articular
margin, to the front surface of the lateral mass, and to the base of the transverse
process; these fibres take an oblique course upwards and inwards, overlapping the
anterior occipito-atlantal. At the sides and behind, the capsule is attached above
to the margins of the occipital condyles; below, it skirts the inner edge of the
foramen for the vertebral artery, and behind is attached to the prominent tubercle
overhanging the groove for that vessel; these latter fibres are strengthened by a
band running obliquely upwards and inwards to the posterior margin of the

foramen magnum.
O

194
THE ARTICULATIONS
The anterior oblique or lateral occipito-atlantal ligament (fig. 195) is an
accessory band which strengthens the capsule on the outer side. It is an oblique,
thick band of fibres, sometimes quite separate and distinct from the rest, passing
upwards and inwards from the upper surface of the transverse process beyond the
costo-vertebral foramen to the jugular process of the occipital bone.
The synovial membrane of these joints occasionally communicates with the
synovial sac between the odontoid process and the transverse ligament.
The arterial supply is derived from twigs of the vertebral, and occasionally
from twigs from the meningeal branches of the ascending pharyngeal.
The nerve-supply comes from the anterior division of the suboccipital nerve.
FIG. 195.-ANTERIOR VIEW OF THE UPPER END OF THE SPINE.
Occipito-
atlantal
capsular
ligament
Continua-
tion of the
anterior
common
ligament
of the
vertebral
column
Anterior
occipito-
atlantal
ligament
The anterior oblique.
or lateral occipito-
atlantal ligament
Atlanto-axoidean.
capsular ligament
Anterior atlanto-
axoidean ligament
Capsular ligaments of
articular processes
between axis and
the third, the third
and fourth, and the
fourth and fifth cer-
vical vertebræ
BODY OF AXIS
Short vertebral
ligament
Anterior common
ligament
Movements. By the symmetrical and bilateral arrangement of these joints,
security and strength are gained at the expense of a very small amount of actual
articular surface; the basis of support and the area of action being equal to the
width between the most distant borders of the joint.
Almost the only movement permitted at these joints is of a ginglymoid character,
producing flexion and extension upon a transverse axis drawn across the condyles
at their slightly constricted parts.
In flexion, the forehead and chin drop, and what is called the nodding move-
ment is made; in extension, the chin is thrown up and the forehead recedes.
There is also a slight amount of gliding movement, either directly lateral, the
outer edge of one condyle sinking a little within the outer edge of the socket of the
ATLAS WITH OCCIPUT
195
atlas, and that of the opposite condyle projecting to a corresponding degree. The
head is thus tilted to one side, and it is even possible that the weight of the skull
may be borne almost entirely on one joint, the articular surfaces of the other being
thrown out of contact.
Or the movement may be obliquely lateral, when the lower side of the head
will be a trifle in advance of the elevated side. In this motion, which takes place
FIG. 196.-VERTICAL ANTERO-POSTERIOR SECTION OF SPINAL COLUMN THROUGH
MEDIAN LINE, SHOWING LIGAMENTS.

Left lateral
odontoid
ligam ent
Ascending
portion of
crucial
ligament
Transverse ligament
Inner part of capsular ligament
of occipito-atlantal joint
Posterior occipito-atlantal
ligament
Descending portion of crucial
ligament
Posterior atlanto-axoidean
ligament
Interspinous ligament
Ligamentum subflavum
Central odontoid
ligament
Anterior occipito-
atlantal ligament
Atlanto-odontoid
synovial sac
Anterior atlanto-
axoidean ligament
on the antero-posterior axis, one condyle advances slightly and approaches the
middle line, while the other recedes. There is no true rotation round a vertical
axis possible between the occiput and atlas.
These lateral movements are checked by the lateral odontoid ligaments and
the outer part of the capsules; extension is checked by the anterior occipito-atlantal
and anterior oblique ligaments, and flexion by the posterior part of the capsule
and cervico-basilar ligaments.
02

196
THE ARTICULATIONS
(b) THE ARTICULATIONS BETWEEN THE ATLAS AND AXIS
1. THE LATERAL ATLANTO-AXOIDEAN JOINTS.
2. THE CENTRAL ATLANTO-AXOIDEAN JOINT.
Class.-Diarthrosis.
Subdivision.-Arthrodia.
Class.-Diarthrosis.
Subdivision.-Trochoides.
The bones that enter into the formation of the lateral joints are the inferior
articular processes of the atlas and the superior of the axis; the central joint is
formed by the odontoid process articulating in front with the atlas, and behind
with the transverse ligament.
The ligaments which unite the axis and atlas are:-
1. The anterior atlanto-axoidean.
2. The posterior atlanto-axoidean.
3. Two capsular (for lateral joints).
4. The transverse ligament.
5. The atlanto-odontoid capsular ligament.
The anterior atlanto-axoidean ligament (figs. 195, 196) is a narrow but strong
membrane filling up the interval between the lateral joints. It is attached, above
to the front surface and lower border of the anterior arch of the atlas, and below
to the transverse ridge on the front of the body of the axis. Its fibres are vertical,
and are thickened in the median line by a dense band which is a continuation
upwards of the anterior common ligament of the spine.
This prolongation is fixed above to the anterior tubercle of the atlas, where it
becomes continuous with the central part of the anterior occipito-atlantal (fig.
195); it is sometimes separated by an interval from the deeper ligament, and is
often described as the superficial atlanto-axoidean ligament. It is in relation with
the longus colli muscle.
The posterior atlanto-axoidean ligament (fig. 195) is a deeper, but thinner
and looser membrane than the anterior. It extends from the posterior root of the
transverse process of one side to that of the other, projecting outwards beyond the
posterior part of the capsules which are connected with it. It is attached above
to the posterior surface and lower edge of the posterior arch of the atlas, and
below to the superior edge of the laminæ of the axis on their dorsal aspect. It
is denser and stronger in the median line, and has a layer of elastic tissue on
its anterior surface like the ligamenta subflava, to which it corresponds in
position. It is connected in front with the dura mater; behind, it is in relation
with the inferior oblique muscles, and is perforated at each side by the second
cervical nerve.
1. The LATERAL ATLANTO-AXOIDEAN JOINTS are provided with short, liga-
mentous fibres, forming capsular ligaments (fig. 195), which completely sur-
round the lateral articular facets. Outside the canal, they are attached some
little distance from the articular margins, extending along the roots of the
transverse processes of the axis nearly as far as the tips, but between the roots they
skirt the inner edge of the costo-vertebral foramina. They are strengthened in front
and behind by the atlanto-axoidean ligaments. Internally each capsule is thinner,
and attached close to the articular margins, being strengthened behind by a
strong band of slightly oblique fibres passing upwards along the outer edge of the
cervico-basilar ligament from the body of the axis to the lateral mass of the
atlas behind the transverse ligament; some of these fibres pass on, thickening
and blending with the occipito-atlantal capsule, getting inserted into the margin of
the foramen magnum. This band is sometimes called the accessory band (fig. 199).
There is a synovial sac for each joint.

BETWEEN ATLAS AND AXIS
197
2. The CENTRAL ATLANTO-AXOIDEAN JOINT, although usually described as one,
is composed of two articulations, which are quite separate from one another: an
anterior between the odontoid process and the arch of the atlas, and a posterior
between the odontoid process and the transverse ligament.
The transverse ligament (figs. 196, 197, and 199) is one of the most important
structures in the body, for on its integrity our lives depend. It is a thick and
very strong band, as dense and closely woven as fibro-cartilage, about a quarter
of an inch (6 mm.) deep at the sides, and somewhat more in the middle line.
Attached at each end to a tubercle on the inner side of the lateral mass of the atlas,
it crosses the ring of this bone in a curved manner, so as to have the concavity
forward; thus dividing the ring into a smaller anterior portion for the odontoid
process, and a larger posterior part for the spinal cord and its membranes, and the
spinal accessory nerves. It is flattened from before backwards, being smooth in
front, and covered by synovial membrane to allow it to glide freely over the
posterior facet of the odontoid process. Where it is attached to the atlas it is
smooth and well rounded off to provide an easy floor of communication between
the transverso-odontoid and occipito-atlantal joints.
FIG. 197.-HORIZONTAL SECTION THROUGH THE LATERAL MASSES OF THE ATLAS
AND THE TOP OF THE ODONTOID PROCESS.

Atlanto-
odontoid
synovial sac
Transverso-
odontoid
synovial sac
Atlanto-odontoid
capsular ligament
Transverse
ligament
Posterior common
and cervico-basilar
ligaments
-Dura mater
To its posterior surface is added, in the middle line, a strong fasciculus of vertical
fibres, passing upwards from the root of the odontoid process to the basilar border
of the foramen magnum on its cranial aspect. Some of these fibres are derived
from the transverse portion. It gives the ligament a cruciform appearance; hence
its name, the crucial ligament (figs. 196, 199).
The atlanto-odontoid capsular ligament (fig. 197) is a tough, loose membrane,
completely surrounding the apposed articular surfaces of the atlas and odontoid
process. At the odontoid process it blends above with the front of the check and
central occipito-odontoid ligaments, and arises also along the sides of the articular
facet as far as the neck of the process; the fibres are thick, and blend with the
capsules of the lateral joint. At the atlas they are attached to the non-articular
part of the anterior arch in front of the tubercles for the transverse ligament,
blending, above and below the borders of the bone, with the anterior occipito-
atlantal and atlanto-axoidean ligaments, as well as with the inner portion of the
capsular ligaments. It holds the axis to the anterior arch of the atlas after all
the other ligaments have been divided.
The synovial membranes (figs. 196, 197) are two in number:-one for the
joint between the odontoid process and atlas; and another (transverso-odontoid)
for that between the transverse ligament and the odontoid; this last often com-
municates with the occipito-atlantal. It is closed in by membranous tissue

198
THE ARTICULATIONS
between the borders of the transverse ligament and the margin of the facet on
the odontoid, and is separated from the front sac by the atlanto-odontoid capsular
ligament.
The arterial supply is from the vertebral artery, and the nerve-supply from the
loop between the first and second cervical nerves.
Movements.-The chief and characteristic movement at these joints is the
rotation, in a nearly horizontal plane, of the collar formed by the atlas and trans-
verse ligament, round the odontoid process as a pivot, which is extensive enough
to allow of an all-round view without twisting the trunk. Partly on account of
its ligamentous attachments, and partly on account of the shape of the articular
surfaces, the cranium must be carried with the atlas in these movements. The
rotation is checked by the ligaments passing from the axis to the occiput (check
ligaments), and also by the atlanto-axoidean. Owing to the fact that the facets
of both atlas and axis, which enter into the formation of the lateral atlanto-
axoidean articulations, are convex from before backwards, and have the articular
cartilage thicker in the centre than at the circumference, the motion is not quite
horizontal but slightly curvilinear. In the erect position, with the face looking
directly forward, the most convex portions of the articular surfaces are alone in
contact, there being a considerable interval between the edges; during rotation,
therefore, the prominent portions of the condyles of the atlas descend upon those
of the axis, diminishing the space between the bones, slackening the ligaments,
and thus increasing the amount of rotation, without sacrificing the security of the
joint in the central position.
Besides rotation, forward and backward movements and some lateral flexion
are permitted between the atlas and axis, even to a greater extent than in most of
the other vertebral joints.
(c) THE LIGAMENTS UNITING THE OCCIPUT AND AXIS
The following ligaments unite bones not in contact, and are to be seen from the
interior of the canal after removing the posterior arches of axis and atlas and
posterior ring of the foramen magnum :-
1. The occipito-cervical.
2. The crucial.
3. Two lateral odontoid or check.
4. The central odontoid or suspensory.
The occipito-cervical or cervico-basilar ligament (figs. 197, 198 and 199) consists
of a very strong band of fibres, connected below to the upper part of the body of
the third vertebra and lower part of the body of the axis as far as the root of the
odontoid process. It is narrow below, but widens out as it ascends, to be fastened
to the basilar groove of the occiput. Laterally, it is connected with the accessory
fibres of the atlanto-axoidean capsule. It is really only the upward prolongation
of the posterior common ligament, some of the fibres of which run on to the
occipital bone without touching the axis, thus giving rise to two strata. It is in
relation in front with the crucial ligament.
The crucial ligament has been already described (see page 197).
The lateral occipito-odontoid or check ligaments (fig. 196 and 199) are two
strong rounded cords, which extend from the sides of the apex of the odontoid
process, transversely outwards to the inner edge of the anterior portion of the
occipital condyles. They are to be seen immediately above the upper border of the
transverse ligament, which they cross obliquely owing to its forward curve at its
attachments to the atlas. Some of their fibres occasionally run across the middle
line from one check ligament to the other. At the odontoid process they are

LIGAMENTS UNITING OCCIPUT AND AXIS
199
FIG. 198.-THE SUPERFICIAL LAYER OF THE POSTERIOR COMMON VERTEBRAL
LIGAMENT HAS BEEN REMOVED TO SHOW ITS DEEP OR SHORT FIBRES. THESE
DEEP FIBRES FORM THE OCCIPITO-CERVICAL LIGAMENT.

Atlanto-axoidean
capsular ligament
Occipito-cervical liga-
ment, i.e. the deep
stratum of the pos-
terior common ver-
tebral ligament.
Transverse process of atlas
FIG. 199.-VERTICAL TRANSVERSE SECTION OF THE SPINAL COLUMN AND THE
OCCIPITAL BONE TO SHOW LIGAMENTS.
(The cervico-basilar (1), though shown as a distinct stratum, is really the
deeper part of the posterior common ligament (2).)

Vertical portion of crucia
ligament
Central odontoid ligament
Lateral odontoid ligaments
Transverse portion of crucial
ligament
Accessory band of atlanto--
axoidean capsules
Atlanto-axoidean joint-
Cervico-basilar ligament
Posterior common ligament


200
THE ARTICULATIONS
connected with the atlanto-odontoid capsule, and at the condyles they strengthen
the occipito-atlantal capsular ligaments.
The central odontoid or suspensory ligament (fig. 196 and 199) consists of a
slender band of fibres ascending from the summit of the odontoid process to the
under surface of the occipital bone, close to the foramen magnum. It is best seen
from the front, after removing the anterior occipito-atlantal ligament, or from
behind by drawing aside the crucial ligament.
The suspensory ligament is tightened by extension and relaxed by flexion or
nodding; the lateral odontoids not only limit the rotatory movements of the head
and atlas upon the axis, but by binding the occiput to the pivot, round which
rotation occurs, they steady the head and prevent its undue lateral inclination.
upon the spine.
By experiments, it has been proved that the head, when placed so that the
orbits look a little upwards, is poised upon the occipital condyles in a line drawn
a little in front of their middle; the amount of elevation varies slightly in different
cases, but the balance is always to be obtained in the human body-it is one of
the characteristics of the human figure. It serves to maintain the head erect
without undue muscular effort, or a strong ligamentum nuchæ and prominent
dorsal spines such as are seen in the lower animals. Disturb this balance, and let
the muscles cease to act, the head will either drop forwards or backwards according
as the centre of the gravity is in front or behind the balance line. The ligaments
which pass over the odontoid process to the occiput are not quite tight when the
head is erect, and only become so when the head is flexed; if this were not so, no
flexion would be allowed; thus, muscular action, and not ligamentous tension, is
employed to steady the head in the erect position. It is through the combination
of the joints of the atlas and axis, and occiput and atlas (consisting of two pairs
of joints placed symmetrically on either side of the median line, while through
the median line there passes a pivot, also with a pair of joints) that the head
enjoys such freedom and celerity of action, remarkable strength, and almost
absolute security against violence, which could only be obtained by a ball-and-socket
joint; but the ordinary ball-and-socket joints are too prone to dislocations by even
moderate twists to be reliable enough when the life of the individual depends on the
perfection of the articulation: hence the importance of this combination of joints.

THE ARTICULATIONS OF THE TRUNK
These may be divided into the following sets :-
1. Those of the vertebral column.
(a) Union of the bodies.
2. Vertebral column with the pelvis.
3. Pelvis.
sets:—
(b) Union of the articular processes.
(a) Sacro-iliac synchondroses. (c) Intercoccygeal.
(b) Sacro-coccygeal.
4. Ribs with the vertebral column.
(d) Symphysis pubis.
5. The articulations at the front of the thorax.
(a) Costal cartilages with the sternum.
(b) Costal cartilages with the ribs.
(c) Sternal.
(d) Certain costal cartilages with each other.
OF VERTEBRAL COLUMN
201
1. THE ARTICULATIONS OF THE VERTEBRAL COLUMN
There are two distinct sets of articulations in the vertebral column:-
(a) Those between the bodies and intervertebral discs which form amphi-
arthrodial joints.
(b) Those between the articular processes which form arthrodial joints.
The ligaments which unite the various parts may also be divided into two
sets, viz.--immediate, or those that bind together parts which are in contact; and
intermediate, or those that bind together parts which are not in contact.
Immediate.
(a) Those between the bodies and discs.
(b) Those between the articular processes.
Intermediate.
(c) Those between the laminæ.
(a) Those between the spinous processes.
(e) Those between the transverse processes.
(a) THE ARTICULATIONS OF THE BODIES OF THE VERTEBRÆ
Class.-Amphiarthrosis.

The ligaments which unite the bodies of the vertebræ are:-
Intervertebral discs.
Short lateral ligaments.
Anterior common.
Posterior common.
FIG. 200.-HORIZONTAL SECTION THROUGH AN INTERVERTEBRAL DISC
AND THE CORRESPONDING RIBS.
Anterior costo-
central or
stellate
ligament
Costo-central
synovial sac
Middle costo-
transverse
ligament
Costo-transverse synovial
sac
Laminar portion of inter-
vertebral disc
Central pulpy portion of inter-
vertebral disc
Posterior costo-transverse
ligament
The intervertebral substances (figs. 196 and 200) are tough, but elastic and
compressible discs of composite structure, which serve as the chief bond of union
between the vertebrae. They are twenty-three in number, and are interposed
between the bodies of all the vertebræ from the axis to the sacrum.
substances are found between the segments of the sacrum and coccyx, but they
Similar

202
THE ARTICULATIONS

undergo ossification at their surfaces and often throughout their whole extent.
(See figs. 196 and 203.)
Each disc is composed of two portions--a circumferential laminar, and a
central pulpy portion; the former tightly surrounds and braces in the latter, and
forms somewhat more than half the disc. The laminar portion consists of alter-
nating layers of fibrous tissue and fibro-cartilage; the component fibres of which
are firmly connected with two vertebræ, and pass obliquely down and to the right
in one layer, and down and to the left in the next, making an X-shaped arrange-
ment of the alternate layers. A few of the superficial lamellæ project beyond the
edges of the bodies, their fibres being connected with the edges of the anterior and
lateral surfaces; and some do not completely surround the rest, but terminate
at the intervertebral foramina, so that on horizontal section the circumferential
portion is seen to be thinner posteriorly. The more central lamellæ are incomplete,
FIG. 201. THE ANTERIOR COMMON LIGAMENT OF THE SPINE, THE STELLATE, AND
THE SUPERIOR COSTO-TRANSVERSE LIGAMENTS.

The interarticular ligament
The superior or anterior
costo-transverse ligaments
The stellate ligament
less firm, and not so distinct as the rest; and as they near the pulp they gradually
assume its characters, becoming more fibro-cartilaginous and less fibrous, and have
cartilage cells in their structure.
The central portion is situated somewhat behind the centre of the disc, forming
a ball of very elastic and tightly compressed material, which bulges freely when
the confining pressure of the laminar portion is removed by either horizontal or
vertical section. Thus, it has a constant tendency to spring out of its confinement
in the direction of least resistance, and thus constitutes a pivot round which the
bodies of the vertebræ can twist, tilt, or incline. It is yellowish in colour, and is
composed of a fine fibrous matrix containing cartilage cells and fluid in its meshes.
Together with the most central laminæ, it is separated from immediate contact
with the bone by a thin plate of articular cartilage. The central pulp of the inter-
vertebral substance is the persistent part of the notochord.
The intervertebral substances vary in shape with the bodies of the vertebræ


OF VERTEBRAL COLUMN
203
they unite, and are widest in area and also thickest in the lumbar region. In the
cervical and lumbar regions they are thicker in front than behind, and cause the
convexity forwards of the cervical, and increase that in the lumbar; the curve in
the thoracic region being almost entirely due to the shape of the bodies, is, however,
somewhat increased by the discs. Without the discs the column loses a quarter of
its length, and assumes a curve with the concavity forward, most marked a little
below the mid-thoracic region. Such is the curve of old age, which is due to the
shrinking and drying up of the intervertebral substances. The disc between the
axis and third cervical is the thinnest of all; that between the fifth lumbar and
sacrum is the thickest, and is much thicker in front than behind. The intervertebral
discs are in relation, in front with the anterior common ligament; behind, with the
FIG. 202.-POSTERIOR COMMON LIGAMENT OF THE SPINE.. (Thoracic region.)
(Pedicles cut through, and posterior arches of vertebræ removed.)

Lateral expanded portion-
Median longitudinal band-
posterior; laterally, with the short lateral; and in the thoracic region with the inter-
articular and stellate ligaments.
The anterior common ligament (figs. 195 and 201) commences as a narrow
band attached to the under surface of the occipital bone in the median line, just
in front of the occipito-atlantal ligament, of which it forms the thickened central
portion.
Attached firmly to the tubercle of the atlas, it passes down as the
central portion of the atlanto-axoidean ligament, in the mid-line, to the front
of the body of the axis. It now begins to widen out as it descends, until it is
nearly two inches (5 cm.) wide in the lumbar region. Below, it is fixed to the
upper segment of the sacrum, becoming lost in periosteum about the middle of
that bone; but is again distinguishable in front of the sacro-coccygeal joint, as
the anterior sacro-coccygeal ligament. Its structure is bright, pearly-white, and
glistening with well-defined borders best marked in the thoracic region. It is

204
THE ARTICULATIONS
thickest in the thoracic region, and thicker in the lumbar than the cervical. It
is firmly connected with the bodies of the vertebræ, and is composed of longitudinal
fibres, of which the superficial extend over several, while the deeper pass over
only two or three vertebræ. It is connected with the tendinous expansion of the
prevertebral muscles in the cervical, and the crura of the diaphragm are closely
attached to it in the lumbar region.
The posterior common ligament (figs. 199, 202, 203, and 209) extends from the
occipital bone to the coccyx. It is wider above than below, and commences by a
broad attachment to the cranial surface of the basi-occipital. In the cervical
region it is of nearly uniform width, and extends completely across the bodies of
the vertebræ, upon which it rests quite flat. It does, however, extend slightly
further outwards on each side opposite the intervertebral discs. In the thoracic
and lumbar regions it is distinctly dentated, being broader over the intervertebral
FIG. 203.-POSTERIOR COMMON LIGAMENT. (Lumbar region.)
Median band
-Expanded lateral portion
substances and the edges of the bones, than over the middle of the bodies, where
it is a narrow band stretched over the bones without resting on them, some
areolar tissue and blood-vessels being interposed. The narrow median portion
consists of longitudinal fibres, some of which are superficial and pass over several
vertebræ; and others are deeper, and extend only from one vertebra to the next
but one below.
The dentated or broader portions (fig. 203) are formed by oblique fibres which,
springing from the bodies near the intervertebral foramina, take a curved course
downwards and backwards over an intervertebral substance, and reach the narrow
portion of the ligament on the centre of the vertebra next below; they then
diverge to pass over another intervertebral disc to end on the body of the vertebra
beyond, near the intervertebral notch. They thus pass over two discs and three

OF VERTEBRAL COLUMN
205
vertebræ. Deeper still are other fibres thickening these expansions of the common
ligament, and extending from one bone to the next.
The last well-marked expansion is situated between the first two segments
of the sacrum: below this, the ligament becomes a delicate central band with rudi-
mentary expansions, being more pronounced again over the sacro-coccygeal joint,
and losing itself in the ligamentous tissue at the back of the coccyx. The dura mater
is tightly attached to it at the occipital bone and margin of the foramen magnum,
but is separated from it in the rest of its extent by loose cellular tissue. The
filum terminale becomes blended with it at the lower part of the sacrum and back
of the coccyx.
The lateral or short vertebral ligaments (fig. 201) consist of numerous short
fibres situated between the anterior and posterior common ligaments, and passing
from one vertebra over the intervertebral disc, to which it is firmly adherent, to
the next vertebra below. The more superficial fibres are more or less vertical,
but the deeper decussate and have a crucial arrangement. They are connected
with the deep surface of the anterior common ligament, and so tie it to the edges
of the bodies of the vertebræ and to the intervertebral discs. They blend behind
with the expansions of the posterior common ligament, and so complete the casing
round each amphiarthrodial joint. In the thoracic region they overlie the stellate
ligament, and in the lumbar they radiate towards the transverse processes. In the
cervical region they are less well marked.
(b) THE LIGAMENTS CONNECTING THE ARTICULAR PROCESSES
Class.-Diarthrosis.
Subdivision.-Arthrodia.

The capsular ligaments (fig. 195) which unite these processes are com-
posed partly of yellow elastic tissue, and partly of white fibrous tissue. In the
cervical region only the inner side of the capsule is formed by the ligamenta
subflava, which in the thoracic and lumbar regions, however, extend anteriorly to the
margins of the intervertebral foramina. The part formed of white fibrous tissue
consists of short, well-marked fibres, which in the cervical region pass obliquely
downwards and forwards over the joint, between the articular processes and the
posterior roots of the transverse processes of two contiguous vertebræ. In the
thoracic region the fibres are shorter, and vertical in direction, and are attached to
the bases of the transverse processes; in the lumbar, they are obliquely transverse.
The capsular ligaments in the cervical region are the most lax, those in the
lumbar region are rather tighter, and those in the thoracic region are the tightest.
There is one synovial membrane to each capsule.
sacrum.
(c) THE LIGAMENTS UNITING THE LAMINE
The ligamenta subflava (fig. 204) are shallow plates of closely-woven yellow
elastic tissue, interposed between the lamina of two adjacent vertebræ. The first
connects the axis with the third cervical, and the last the fifth lumbar with the
Each ligament extends from the inner and posterior edge of the inter-
vertebral foramen on one side to a corresponding point on the other; above, it is
attached close to the inner margin of the inferior articular process and to a well-
marked ridge on the inner surface of the lamina as far as the root of the spine;
below, it is fixed close to the inner margin of the superior articular process and to
the dorsal aspect of the upper edge of the lamina. Each thus, besides filling up
the interlaminar space, enters into the formation of two capsular ligaments; they
do so to a greater extent in the thoracic and lumbar regions than in the cervical,
where the articular processes are placed wider apart. They are concave from side to

206
THE ARTICULATIONS
side, but convex from above downwards in front, making a more decided transverse
curve than the arches between which they are placed. This concavity is more
marked in the thoracic, and still more in the lumbar region than in the cervical, as
the ligamenta subflava in the former region extend a short distance between the
roots of the spinous process, blending with the interspinous ligament, and making
FIG. 204.-LIGAMENTA SUBFLAVA IN THE LUMBAR REGION.
Portion of ligamen--
tum subflavum re-
moved to show the
articular cavity
Ligamentum-
subflavum
a median sulcus when seen from the front; there is, however, no separation
between the two parts. In the cervical region, where the spines are bifid, there
is a median fissure which is filled up by fibro-areolar tissue. The ligaments are
thickest and strongest in the lumbar region; narrow but strong in the thoracic;
thinner, broader, and more membranous in the cervical region.
(d) THE LIGAMENTS CONNECTING THE SPINOUS PROCESSES WITH ONE ANOTHER
(e) THE LIGAMENTS CONNECTING THE TRANSVERSE PROCESSES WITH
ONE ANOTHER
Supraspinous.-Interspinous.-Intertransverse.
The supraspinous ligament (fig. 205) extends all along the tips of the spines
as a well-marked band of longitudinal fibres, from the spine of the seventh cervical
vertebra to the coccyx, where it blends with the fibrous tissue on the back of that
bone, covering in the lower end of the spinal canal, and adding to the security of
the sacro-coccygeal joint. It is continuous at the sides with the aponeurotic
structures of the back, and above with the ligamentum nuchæ, beneath which a
thin tendinous continuation of the supraspinous ligament is attached along the
spines of the cervical vertebræ. It is thicker in the lumbar region than in the
thoracic. Its deeper fibres pass over adjacent spines only, while the superficial
overlie several.

OF VERTEBRAL COLUMN
207
The interspinous ligaments (fig. 205) are thin membranous structures which
extend between the spines, and are connected with the ligamenta subflava in front,
and the supraspinous ligament behind. The fibres pass obliquely from the root
of one spine to the tip of the next; they thus decussate. They are best marked in
the lumbar region, and are replaced by the well-developed interspinales muscles in
the cervical region.
The intertransverse ligaments are barely worth the name; in the thoracic
region they form small rounded bundles, and in the lumbar they are thin mem-
branous bands, quite incapable of action as bonds of union. They consist of fibres
passing between the apices of the transverse processes. In the cervical region
they are replaced by the intertransversales muscles.
The arterial supply for the column comes from twigs of the vertebral, ascending
pharyngeal, ascending cervical, superior and aortic intercostals, lumbar, ilio-lumbar,
and lateral sacral.
FIG. 205.-THE INTERSPINOUS AND SUPRASPINOUS LIGAMENTS IN THE
LUMBAR REGION.
The interspinous ligament
The supraspinous ligament
The nerve-supply comes from the spinal nerves of each region.
Movements. The spinal column is so formed of a number of bones and inter-
vertebral discs as to serve many purposes. It is the axis of the skeleton; upon
it the skull is supported; and with it the cavities of the trunk, and the limbs
are connected. As a fixed column it is capable of bearing great weight; and,
through the elastic intervertebral substances, of resisting and breaking the trans-
mission of shocks. Moreover, it is flexible, and therefore capable of movement.
Now, the range of movements of the column as a whole is very considerable; but
movements between any two vertebræ are slight, so that motions of the spine
may take place without any change in the shape of the column, and without any
marked disturbance in the relative positions of the vertebræ. It is about the pulpy
part of the intervertebral discs, which form a central elastic pivot or ball, upon
which the middle of the vertebræ rest, that these movements take place.
the
The amount of motion is everywhere limited by the common vertebral

208
THE ARTICULATIONS
ligaments, but it depends partly upon the width of the bodies of the vertebræ, and
partly upon the depth of the discs, so that in the loins, where the bodies are large
and wide, and the discs very thick, free motion is permitted; while, though the
discs are thinner in the cervical region, yet, as the bodies are smaller, almost equally
free motion is allowed. As the ball-like pulpy part of the intervertebral disc is the
centre of movement of each vertebra, it is obvious that the motion would be of a
rolling character in any direction but for the articular processes, which serve also
to give steadiness to the column and to assist in bearing the superincumbent
weight. Were it not for these processes, the column, instead of being a stationary
one, endowed with the capacity of movement by muscular agency, would be a
tottering one, requiring muscles to steady it. The influence of the articular
processes in limiting the direction of inclination will appear from a study of
the movements in the three regions of the spine.
In the neck, the obliquity of the processes permits all movements, but is
especially favourable for extension. Flexion is less free here than in the lumbar
region, while extension is more so. Lateral flexion is more free in the neck than
in any other region. Rotatory movements are also free in the neck, especially
in the lower part. There is but slight movement of any sort between the axis
and third cervical vertebra, owing to the shallow intervertebral disc and the great
prolongation of the anterior lip of the inferior surface of the body of the axis,
which checks forward flexion considerably.
In the thoracic region, especially near its middle, antero-posterior flexion and
extension are very slight; and, as the concavity of the curve here is forwards, the
flat and nearly vertical surfaces of the articular processes prevent anything like
sliding in a curvilinear manner of the one set of processes over the sharp upper
edges of the other, which would be necessary for forward flexion. A fair amount.
of lateral flexion would be permitted but for the impediment offered by the ribs;
while the slightly outward inclination of the superior process, and inward inclina-
tion of the inferior, allow a little rotation, which is freer in the upper than in the
lower part of the thoracic region.
in
In the lumbar region, extension and flexion are very free, especially between
the third and fourth, and fourth and fifth vertebræ, where the lumbar curve is
sharpest; lateral inclination is also very free between these same vertebræ. It
has been stated that the shape and position of the articular processes of the lumbar
and the lower two or three dorsal are such as to prevent any rotation in these
regions; but, owing to the fact that the inferior articular processes are not tightly
embraced by the superior, so that the two sets of articular processes are not in
contact on both sides of the bodies at the same time, there is always some space
which horizontal motion can occur round an axis drawn through the central part.
of the bodies and intervertebral discs. Thus, the motions are most free in those
regions of the column which have a convex curve forwards, due to the shape of the
intervertebral discs, where there are no bony walls surrounding solid viscera, where
the spinal canal is largest and its contents are less firmly attached, and where the
pedicles and articular processes are more nearly on a transverse level with the
backs of the bodies of the vertebræ.
Nor must the uses of the ligamenta subflava be forgotten: these useful little.
structures (1) complete the roofing-in of the spinal canal, and yet at the same time.
permit an ever-changing variation in the width of the interlaminar spaces in flexion
and extension; (2) they also restore the articulating surfaces to their normal posi-
tion with regard to each other after movements of the column; (3) and by forming
the inner portion of each capsular ligament they take the place of muscle, in pre-
venting it from being nipped between the articular surfaces during movement.
OF PELVIS WITH THE SPINE
209
2. THE ARTICULATIONS OF THE PELVIS WITH THE SPINE
As in the intervertebral articulations, so in the union of the first portion of the
sacrum with the last lumbar vertebra, there are two sets of joints-viz. an amphi-
arthrodial one, between the bodies and intervertebral disc; and a pair of arthrodial
joints, between the articular processes. The union is effected by the following
ligaments, which are common to the spinal column :-(i) anterior, and (ii) posterior,
common; (iii) lateral or short vertebral; (iv) capsular; (v) ligamentum subflavum ;
(vi) supra- and (vii) interspinous, ligaments; and two special accessory ligaments
on either side, viz. (viii) sacro-lumbar; and (ix) ilio-lumbar.
The sacro-lumbar ligament (fig. 206) is strong, and triangular in shape. Its
apex is above and internal, being attached to the whole of the lower border and
front surface of the transverse process of the fifth lumbar vertebra, as well as to the
pedicle and body. It is intimately blended with the ilio-lumbar ligament. Below,
it has a wide fan-shaped attachment, extending from the edge of the ilio-lumbar
ligament forwards to the brim of the true pelvis; blending with the periosteum on
the base of the sacrum and in the iliac fossa, and with the superior sacro-iliac
ligament. By its sharp internal border it limits externally the foramen for the
last lumbar nerve. It is pierced by two large foramina, which transmit arteries to
the sacro-iliac synchrondrosis.
The ilio-lumbar ligament (fig. 206) is a strong, dense, triangular ligament,
which springs from the front surface of the transverse process of the fifth lumbar
vertebra as far as the body, by a strong fasciculus from the posterior surface of the
process near the tip, and also from the front surface and lower edge of the transverse
process and pedicle of the fourth lumbar vertebra, as far inwards as the body.
Between these two vertebræ it is inseparable from the intertransverse ligament.
At its origin from the transverse process of the fifth lumbar vertebra, it is closely
interwoven with the sacro-lumbar ligament, and some of its fibres spread down-
wards on to the body of the fifth vertebra, while others ascend to the disc above.
At the pelvis it is attached to the inner lip of the crest of the ilium for about
two inches (5 cm.). The highest fibres at the spine form the upper edge of the
ligament at the pelvis, those which come from the posterior portion of the
transverse process of the fifth lumbar vertebra forming the lower, while the fibres
from the front of the same process pass nearly horizontally outwards.
Near the spine the surfaces look directly backwards and forwards, but at the
ilium, the ligament gets somewhat twisted, so that the posterior surface looks a little
upwards, and the anterior looks a little downwards.
The anterior surface forms part of the posterior boundary of the false pelvis,
and overlies the upper part of the posterior sacro-iliac ligament; the posterior
surface forms part of the floor of the spinal groove, and gives origin to the multifidus
spine muscle. Of the borders, the upper is oblique, has the anterior lamella of the
lumbar fascia attached to it, and gives origin to the quadratus lumborum; the lower
is horizontal, and is adjacent to the upper edge of the sacro-lumbar ligament; while
the inner is crescentic, and forms the outer boundary of a foramen through which
the fourth lumbar nerve passes.
The arterial supply is very free, and comes from the last lumbar, ilio-lumbar,

and lateral sacral.
The nerve-supply is from the sympathetic, as well as from twigs from the fourth
and fifth lumbar nerves.
Movements.-The angle formed by the sacrum with the spinal column is called
the sacro-vertebral angle. The pelvic inclination does not depend entirely upon
this angle, but in great part upon the obliquity of the innominate bones to the
P

210
THE ARTICULATIONS
sacrum, so that in males in whom the average pelvic obliquity is a little greater,
the average sacro-vertebral angle is considerably less than in females.
The sacro-vertebral angle in the male shows that there is a greater and more
sudden change in direction at the sacro-vertebral union than in the female. A part
of this change in direction is due to the greater thickness in the anterior part of
the intervertebral substance between the last lumbar vertebra and the sacrum.
Owing to the greater thickness of the intervertebral disc here than elsewhere,
the movements permitted at this joint are very free, being freer than those
between any two lumbar vertebræ. As the diameter of the two contiguous bones
is less antero-posteriorly than laterally, the forward and backward motions are
much freer than the lateral ones. The backward and forward motions take place
FIG. 206.-ANTERIOR VIEW OF THE PELVIS.
The ilio-lumbar
ligament
The sacro-lumbar
ligament
-Superior sacro-
iliac ligament
Anterior sacro-
iliac ligament
Great sacro-sciatic
ligament
Lesser sacro-sciatic
ligament
every time the sitting is exchanged for the standing position, and the standing for
the sitting posture; in rising, the back is extended on the sacrum at the sacro-
lumbar union; in sitting down it is flexed.
The articular processes provide for the gliding movement incidental to the
extension, flexion, and lateral movements; they also allow some horizontal move-
ment, necessary for the rotation of the spine on the pelvis, or pelvis on the spine.
The inferior articular processes of the fifth differ considerably from the inferior
processes in the rest of the lumbar vertebræ, and in direction they resemble some-
what those of the cervical vertebræ; while the superior articular processes of
the sacrum differ in a similar degree from the superior processes of the lumbar
vertebræ. This difference allows for the freer rotation which occurs at this joint.
OF THE PELVIS
211
The sacro-vertebral angle averages 117° in the male, and 130° in the female;
while the pelvic inclination averages 155° in the male, and 150° in the female.
3. THE ARTICULATIONS OF THE PELVIS
This group may again be subdivided into-
(a) The sacro-iliac.
(b) The sacro-coccygeal.
(c) The intercoccygeal.
(d) The symphysis pubis.
(a) THE SACRO-ILIAC SYNCHRONDROSIS AND SACRO-SCIATIC LIGAMENTS
Class.-Amphiarthrosis.
Like the symphysis pubis, the sacro-iliac synchondrosis is an amphiarthrodial
joint, but it differs from it in having an interosseous ligament as well as an
interosseous, or symphysial, cartilage. The bones which enter into the joint are
the sacrum and ilium, and they are bound together by the following ligaments :-
Anterior sacro-iliac.
Posterior sacro-iliac.
Interosseous.
Superior sacro-iliac.
Inferior sacro-iliac.

The anterior sacro-iliac ligament (figs. 206, 207) consists of well-marked
glistening fibres which pass above into the superior, and below into the inferior,
ligaments. It extends from the first three bones of the sacrum to the ilium between
the brim of the true pelvis and the great sacro-sciatic notch, blending with the
periosteum of the sacrum and ilium as it passes away from the united edges of the
bones.
The superior sacro-iliac ligament (figs. 206, 207) extends across the upper
margins of the joint, from the base of the sacrum to the iliac fossa, being well
marked along the brim of the pelvis, where it is thickened by some closely-packed
fibres. Behind, it is far stronger, especially beneath the transverse process of the
fifth lumbar vertebra. This ligament is connected with the strong sacro-lumbar
ligament, which spreads outwards and forwards over the joint to reach the iliac
fossa and ilio-pectineal line.
The posterior sacro-iliac ligament is of very great strength, extending between
the back of the sacrum and the posterior two inches of the iliac crest, including the
posterior superior spine. Strengthening the upper and back part of this fibrous
expansion are some strong bundles of ligamentous fibres, which extend more or less
transversely from the inner surface of the iliac crest: (i) to the articular process of
the first sacral vertebra; (ii) to the bone between the articular process and the first
sacral foramen; and (iii) to the articular tubercle of the second sacral vertebra,
forming a ridge over the second sacral foramen under which the nerve passes; an
oblique band often connects this last fasciculus with the articular process of the
first sacral vertebra. Below this, the fibres pass downwards and inwards from the
last inch of the iliac crest to the side of the sacrum external to the second and
third posterior sacral foramina. To the outer edge of this ligament is attached the
fascia covering the erector spinæ muscle.
The inferior sacro-iliac ligament (fig. 207) is covered behind by the upper end
of the great sacro-sciatic ligament; it consists of strong fibres extending from the
lateral border of the sacrum below the articular facet, to the posterior iliac spines;

P2

212
THE ARTICULATIONS
some of the fibres are attached to the deep surface of the ilium and join the inter-
osseous ligament.
The interosseous ligament is the strongest of all, and consists of fibres of
different lengths passing in various directions between the two bones. Immediately
above the interspinous notch of the ilium the fibres of this ligament are very strong,
and form an open network, in the interstices of which is a quantity of fat in which
the articular vessels ramify.
The ear-shaped cartilaginous plate, which unites the bones firmly, is accurately
applied to the auricular surfaces of the sacrum and ilium. It is about one-twelfth of an
inch (2 mm.) thick in the centre, but becomes thinner towards the edges. Though
closely adherent to the bones, it tears away from one entirely, or partially from both,
on the application of violence, sometimes breaking irregularly so that the greater
portion remains connected with one bone, leaving the other bone rough and bare.
FIG. 207.-VERTICAL ANTERO-POSTERIOR SECTION OF THE PELVIS.
Superior sacro-iliac.
ligament
Anterior sacro-iliac-
ligament
Inferior sacro-iliac-
ligament
Small sacro-sciatic
ligament
Great sacro-sciatic
ligament
It is really one mass, and is only occasionally formed of two plates with a synovial
cavity between them: when this is the case the joint becomes an arthrodial one.
The great or posterior sacro-sciatic ligament (figs. 206, 207 and 208) is attached
above to the posterior extremity of the crest of the ilium and the external aspect of
the posterior iliac spines. From this attachment some of its fibres pass down-
wards and backwards to be attached to the outer borders and posterior surfaces of
the lower three sacral vertebræ and upper two segments of the coccyx; while others,
after passing for a certain distance backwards, curve forwards and downwards
to the ischium forming the anterior free margin of the ligament where it limits
posteriorly the sacro-sciatic foramina. These fibres are joined by others which arise
from the posterior surface of the lower three sacral vertebræ and upper pieces of the
coccyx. At the ischium it is fixed to the inner border of the great tuberosity, and
sends a thin sharp process upwards along the ramus of the ischium which is called
OF THE PELVIS
213
the falciform process (fig. 208), and is a prolongation of the posterior edge of the
ligament. A great many fibres pass on directly into the tendon of the biceps
muscle, so that traction on this muscle braces up the whole ligament, and the
coccyx is thus made to move on the sacrum. The ligament may not unfairly be
described as a tendinous expansion of the muscle, whereby its action is extended
and a more advantageous leverage given. It is thin and flat at its attached ends,
but narrow and thicker in the centre, looking like two triangular expansions joined
by a flat band, the larger triangle being at the ilium, and the smaller at the
ischium. The fibres of the ligament are twisted upon its axis at the narrow part,
so that some of the superior fibres pass to the lower border.
The posterior surface gives origin to the gluteus maximus muscle, and on it
ramify the loops from the posterior branches of the sacral nerves; its anterior surface
is closely connected at its origin with the small sacro-sciatic ligament, and some
FIG. 208.-SACRO-SCIATIC LIGAMENTS. (Posterior view.)

Posterior or great sacro-
sciatic ligament
Anterior or small sacro-
sciatic ligament
Falciform process of the
great ligament
Tendon of biceps muscle, continuous with
the great sacro-sciatic ligament
fibres of the pyriformis muscle arise from it; below, the obturator internus passes out
of the pelvis under its cover, and the internal pudic vessels and nerve pass in. At the
ilium, its posterior edge is continuous with the vertebral aponeurosis; while to the
anterior edge is attached the thick fascia covering the gluteus medius. The obturator
fascia is attached to its falciform edge. It is pierced by the coccygeal branches of
the sciatic, and a branch from the fourth sacral nerve.
The small sacro-sciatic ligament (figs. 206, 207 and 208) is triangular and thin,
springing by a broad base from the lateral border of the sacrum and coccyx, from
the front of the sacrum both above and below the level of the fourth sacral foramen,
and from the coccyx nearly as far as its tip. By its apex it is attached to the front
surface and the borders of the ischial spine as far outwards as its base. Its fibres
decussate so that the lower ones at the coccyx become the highest at the ischial
spine; muscular fibres are often seen intermingled with the ligamentous.
It is situated in front of the great sacro-sciatic ligament, with which it is closely

214
THE ARTICULATIONS
connected at the sacrum, and separates the greater from the lesser sacro-sciatic
foramen. Its front surface gives attachment to the coccygeus muscle, which
overlies it. Behind, it is connected with, and hidden by, the great sacro-sciatic
ligament, so that only the outer inch (2 cm.) and a small part of its attachment to
the coccyx, can be seen; the internal pudic nerve also passes over the posterior
surface.
The arterial supply comes from the gluteal, ilio-lumbar, and lateral sacral.
The nerve-supply is from the superior gluteal, sacral plexus, and external twigs
of the posterior divisions of the first and second sacral nerves.
The movements. It is quite clear, from the nature of the osseous surfaces, from
the wedge-shape of the sacrum, and the manner in which it is locked in between
the hip bones, as well as from the amphiarthrodial character of the articulation,
that there can be no movement at the sacro-iliac joint. While the joint serves the
useful purpose of breaking shocks, the cartilage is too thin and too firmly fixed to
the bones to allow even of appreciable yielding, such as occurs upon the inter-
vertebral discs.
The double wedge-shape of the sacrum, with its broader surface at the base and
in front, prevents dislocation from forces acting from above downwards, and from
before backwards..
The sinuous character of the opposed surfaces of the sacrum and ilium, the
forward and inward direction of the fibres of the posterior sacro-sciatic ligament
which pass from ilium to sacrum, as well as the ilio-lumbar and sacro-lumbar
ligaments, prevent forward displacement of the base of the sacrum; while the
sacro-sciatic ligaments prevent the tilting backwards of its apex. Thus rotation
forwards is entirely prevented.
The shape of the sacrum prevents its downward displacement, while the weight
of the spine and the ligaments, which fasten the sacrum to the ilium, are sufficient
to check its upward displacement.
The anterior and downward displacements of the sacrum are prevented by the
interosseous and posterior sacro-sciatic ligaments, which pass from the ilia to the
sacrum, and suspend the latter, acting somewhat in the same manner as the chains
of a suspension bridge. They also bind the two bones more tightly together: the
greater the pressure, the tighter the union. The suspension bridge arrangement of
the sacro-iliac synchondrosis is admirably adapted to give strength to the pelvis.
(b) THE SACRO-COCCYGEAL ARTICULATION
Class.-Amphiarthrosis.
The last piece of the sacrum and first piece of the coccyx enter into this union,
and are bound together by the following ligaments:
Anterior sacro-coccygeal.
Posterior sacro-coccygeal.
Intervertebral substance.
Supracornual.
Intertransverse.
The intervertebral substance is a small oval disc, three-quarters of an inch
(about 2 cm.) wide, and a little less from before backwards, closely connected
with the surrounding ligaments. It resembles the other discs in structure, but
is softer and more jelly-like, though the lamina of the fibrous portion are well
marked.
The anterior sacro-coccygeal ligament is a prolongation of the glistening fibrous
structure on the front of the sacrum. It is really the lower extremity of the
anterior common ligament, which is thicker over this joint than over the central
part of either of the bones.
OF THE SACRUM AND COCCYX
215
The posterior sacro-coccygeal ligament (fig. 209) is a direct continuation of the
posterior common ligament of the column, consisting of a narrow band of closely
packed fibres, which become blended at the lower border of the first segment of the
coccyx with the filum terminale and supracornual ligament.
The supracornual ligament (fig. 209) is the prolongation of the supraspinous,
which becomes inseparably blended with the aponeurosis of the erector spina opposite
the lamina of the third sacral vertebra, and is thus prolonged downwards upon the
back of the coccyx, passing over and roofing in the lower end of the spinal canal
where the laminæ are deficient. The median fibres (the supraspinous ligament)
extend over the back of the coccyx to its tip, blending with the posterior sacro-
coccygeal ligament and filum terminale; the deeper fibres run across from the
FIG. 209.-LIGAMENTS CONNECTING SACRUM AND COCCYX POSTERIORLY.

Superficial part of.
the supraspinous
ligament, turned
up
Deep part of the
supraspinous liga-
ment, turned up
Intertransverse
ligament
Lower end of the
posterior com-
mon ligament
Supracornual ligament
connecting the cornua
of the sacrum and
coccyx, cut and turned
down
stunted laminæ on one side to the next below on the opposite side, and from the
sacral cornua on one side to the coccygeal on the opposite, some passing between the
two cornua of the same side, and bridging the aperture through which the fifth sacral
nerve passes. Its posterior surface gives origin to the gluteus maximus muscle.
The intertransverse ligament (fig. 209) is merely a quantity of fibrous tissue
which passes from the transverse process of the coccyx to the laterhl edge of the
sacrum below its angle. It is connected with the sacro-sciatic ligaments at their
attachments, and the fifth sacral nerve escapes behind it. It is perforated by twigs
from the lateral sacral artery and the coccygeal nerve.
The arterial supply is from the lateral sacral and sacro-median arteries.
The nerves come from the fourth and fifth sacral and coccygeal nerves.
The movements permitted at this joint are of a simple forward and backward,
or hinge-like character. In the act of defecation, the bone is pushed back by the

216
THE ARTICULATIONS
fæcal mass, and, in parturition, by the foetus; but this backward movement is
controlled by the upward and forward pull of the levator ani and coccygeus. The
external sphincter also tends to pull it forward.
(c) INTERCOCCYGEAL JOINTS
The several segments of the coccyx are held together by the anterior and
posterior common ligaments, which completely cover the bony nodules on their
anterior and posterior aspects. Laterally, the sacro-sciatic ligaments, being attached
to nearly the whole length of the coccyx, serve to connect them. Between the first
and second pieces of the coccyx there is a very perfect amphiarthrodial joint, with
a well-marked intervertebral substance.
(d) THE SYMPHYSIS PUBIS
Class.-Amphiarthrosis.
The bones entering into this joint are the pubic portions of the hip bones.
This joint is shorter and broader in the female than in the male. The ligaments,
which completely surround the articulation, are:-
Superior.
Inferior.
Anterior.
Posterior.
Interosseous cartilage.
The superior ligament (figs. 210 and 211) is a well-marked stratum of yellowish
fibres which extends outwards along the crest of the pubes on each side, blending
in the middle line with the interosseous cartilage. It is continuous in front with
the deep transverse fibres of the anterior ligament, and behind with the posterior
ligament. It gives origin to the rectus abdominis tendon.
FIG. 210.-ANTERIOR VIEW OF THE SYMPHYSIS PUBIS (MALE), SHOWING THE DECUSSATION
OF THE FIBRES OF THE ANTERIOR LIGAMENT.
Superior pubic ligamen
Inferior pubic ligament
The posterior ligament (fig. 212) is slight, and, excepting above and below,
consists of little more than thickened periosteum. Near the upper part is a band
of strong fibres, reaching the whole width of the pubic bones, and continuous with
the thickened periosteal fibres along the ilio-pectineal line. Below, many of the
upper and superficial fibres of the infrapubic ligament ascend over the back of the
joint, and interlace across the median line with fibres from the opposite side nearly
as high as the middle of the symphysis.

THE SYMPHYSIS PUBIS
217
The anterior ligament (figs. 210 and 211) is thick and strong, and is closely
connected with the fascial covering of the muscles arising from the body of the
pubes. It consists of several strata of thick decussating fibres of different degrees
of obliquity, the superficial being the most oblique, and extending lowest over the
joint. The most superficial descending fibres extend from the upper border of the
pubis, cross others from the opposite side about the middle of the symphysis, and
FIG. 211.-ANTERIOR VIEW OF THE SYMPHYSIS PUBIS (FEMALE SHOWING GREATER
WIDTH BETWEEN THE BONES).

Superior pubic ligament
Inferior pubic ligament

are attached to the ramus of the opposite bone. The most superficial ascending
fibres come from the infrapubic ligament, arch upwards, and decussate with other
fibres across the middle line, and are lost on the opposite side beneath the
descending set. There is another deeper set of descending fibres which arise below
the angle, but do not descend so far as the superficial; and a deeper set of ascend-
ing, which decussate, and reach higher than the superficial set, and are connected
FIG. 212.-POSTERIOR VIEW OF THE SYMPHYSIS PUBIS, SHOWING THE BACKWARD
PROJECTION OF THE SYMPHYSIAL SUBSTANCE AND THE DECUSSATION OF THE
FIBRES FROM THE INFERIOR PUBIC LIGAMENT.

Inferior pubic ligament
with the infrapubic ligament. Some few transverse fibres pass from side to side,
especially above and below the points of decussation.
The inferior or infrapubic ligament (figs. 210, 211 and 212) is a thick, arch-like
band of closely packed fibres which fills up the angle between the pubic rami, and
forms a smooth, rounded summit to the pubic arch. On section, it is yellowish
in colour and three-eighths of an inch (1 cm.) thick in the middle line; it is

218
THE ARTICULATIONS
inseparably connected with the interosseous cartilage. Both on the front and back
aspects of the joint it gives off decussating fibres, which, by their interlacement
over the anterior and posterior ligaments of the symphysis, add very materially to
its security. In fact, the ligament may be said to split superiorly into two layers,
one passing over the front, and the other over the back of the articulation. It is
sometimes known as the ligamentum arcuatum.
The interosseous cartilage varies in thickness in different subjects, but is
thicker in the female than in the male. It is thicker in front than behind, and
projects beyond the edges of the bones, especially posteriorly (see fig. 212), blending
intimately with the ligaments at its margins. It is sometimes uninterruptedly
woven throughout, but at others has an elongated narrow fissure, partially dividing
the cartilage into two plates, with a little fluid in the interspace (fig. 213). This is
situated towards the upper and posterior aspects, but does not reach to either, and
usually extends about half the length of the cartilage. The interosseous cartilage
is intimately adherent to the rough osseous surface of the bone, which is ridged
to give it a firmer attachment; and, on forcing the bones apart, it does not usually
split into two plates, but is torn from the bone on one side or the other.
FIG. 213.-SECTION OF SYMPHYSIS TO SHOW THE SYNOVIAL CAVITY.
The arterial supply is from twigs of the internal pudic, pubic branches of the
obturator and epigastric, and ascending branches of the internal circumflex and
superficial external pudic.
The nerve-supply has not been satisfactorily made out.
The movements amount only to a slight yielding of the cartilage; neither
muscular force nor extrinsic forces produce any appreciable movement in the
ordinary condition. Occasionally, as the result of child-bearing, the joint becomes
unnaturally loose, and then walking and standing are painfully unsteady. It is
known that, during pregnancy and parturition, the symphysial cartilage becomes
softer and more vascular, so as to permit the temporary enlargement of the pelvis;
but it must be remembered that the fibres of the oblique muscles decussate, and
thus, during labour, while they force the head of the foetus down, they strengthen
the joint by bracing the bones more tightly together.
4. THE ARTICULATIONS OF THE RIBS WITH THE VERTEBRÆ
These consist of two sets, viz. :-
(a) The costo-central: i.e. the articulation of the head of the rib with the
vertebræ.
(b) The costo-transverse, or the articulation of the tubercle (of each of the
OF THE RIBS WITH VERTEBRE
219
first ten ribs) with the transverse process of the lower of the two vertebræ, with
which the head of the rib articulates: i.e. the one bearing its own number, as
the first rib with the first thoracic vertebra, the second rib with the second
thoracic vertebra, and so on.
(a) THE COSTO-CENTRAL ARTICULATION
Class.-Diarthrosis.
Subdivision. Ginglymo-Arthrodia.
It is a very perfect joint, into the formation of which the head of the rib and
two vertebræ, with the intervertebral disc between them, enter. In the case of the
first, tenth, eleventh, and twelfth ribs, it is formed by the head of the rib articulating
with a single vertebra.
The ligaments are:-
Capsular.
Interarticular.
Stellate or anterior costo-central.
The capsular ligament (fig. 214) consists of short, strong, woolly fibres, com-
pletely surrounding the joint, which are attached to the bones and intervertebral
substances, a little beyond their articular margins. At its upper part it reaches
through the intervertebral foramen towards the back of the bodies of the vertebræ,
FIG. 214.-THE CAPSULAR LIGAMENTS OF THE COSTO-VERTEBRAL JOINTS.

Spinous process of
seventh cervical
vertebra
Capsular ligament of the first costo-.
transverse joint
Capsular ligament of first
costo-central joint
FIRST RIB
being strengthened here by fibres which at intervals connect the anterior with
the posterior common ligaments. The lower fibres extend downwards nearly to
the demi-facet of the rib below; behind, it is continuous with the middle costo-
transverse ligament, and in front is overlaid by the stellate.
The interarticular ligament (fig. 215) consists of short, strong fibres, closely
interwoven with the outermost ring of the intervertebral disc, and attached to the
transverse ridge separating the articular facets on the head of the rib. It com-
pletely divides the articulations into two parts, but does not brace the rib tightly
to the spine, being loose enough to allow a moderate amount of rotation on its
own axis. There is no interarticular ligament in the costo-vertebral joints of the
first, tenth, eleventh, and twelfth ribs.
The anterior costo-central or stellate ligament (figs. 215 and 216) is the most
striking of all, and consists of bright, pearly-white fibres attached to the anterior

220
THE ARTICULATIONS
surface, and upper and lower borders of the neck of the rib, a little way beyond
the articular facet; from this they radiate upwards, forwards, and downwards,
so as to form a continuous layer of distinct and sharply defined fibres. The
FIG. 215.-SHOWING THE ANTERIOR COMMON LIGAMENT OF THE SPINE, AND THE
CONNECTION OF THE RIBS WITH THE VERTEBRÆ.
The interarticular ligament
The superior or anterior
costo-transverse ligaments
The stellate ligament
FIG. 216.-HORIZONTAL SECTION THROUGH THE INTERVERTEBRAL DISC AND RIBS.
Anterior cc sto-
central cr
stellate
ligament
Costo-central
synovial sac
Middle costo-
transverse
ligament
Costo-transverse synovial
sac
Laminar portion of inter-
vertebral disc
Central pulpy portion of inter-
vertebral disc
Posterior costo-transverse
ligament
middle fibres run straight forward to be attached to the intervertebral disc; the
upper ascend to the lower half of the lateral surface of the vertebra above, and
the lower descend to the upper half of the vertebra below.
OF THE RIBS WITH VERTEBRE
221
The stellate ligament is overlapped at the spine by the short vertebral ligaments.
In the case of the first, tenth, eleventh, and twelfth ribs, which articulate with
one vertebra, the ligament is not quite so distinctly stellate, but even in these the
ascending fibres reach the vertebra above that with which the rib articulates.
The synovial membranes (fig. 216) consist of two closed sacs which do not
communicate: one above, and the other below the interarticular ligament. In
the case of the first, tenth, eleventh, and twelfth articulations, there is but one
synovial membrane, as these joints have no interarticular ligament.
The arterial supply is from the intercostal arteries, the twigs piercing the
stellate and capsular ligaments.
The nerve-supply comes from the anterior primary branches of the intercostal
nerves.
The movements are ginglymoid in character, and limited to a slight degree of
elevation and depression around an obliquely horizontal axis corresponding with
the interarticular ligament; there is also a slight amount of forward and backward
gliding, and occasionally a slight degree of screwing or rotatory movement. There
is a considerable difference in the degree of mobility of the different ribs, for while
the first rib is almost immobile except in a very deep inspiration, the mobility of
the others increases from the second to the last; the two floating ribs being the
most mobile of all. The head of the rib is the most fixed point of the costal arch,
and upon it the whole arch rotates; the interarticular ligament allows only a very
limited amount of flexion and extension (i.e. elevation and depression), and of
gliding. Gliding is checked by the stellate ligament.
In inspiration, the rib is elevated, and glides forwards in its socket, too great
elevation being checked not only by the ligaments, but also by the overhanging
upper edge of the cavity itself. In expiration, the rib is depressed, and glides back
in its cavity.
(b) THE COSTO-TRANSVERSE ARTICULATION
Class.-Diarthrosis.
Subdivision.-Arthrodia.
This joint is formed by the tubercle of the rib articulating with the anterior
part of the tip of the transverse process. The eleventh and twelfth ribs are
devoid of these joints, for the tubercles of these ribs are absent, and the transverse
processes of the eleventh and twelfth thoracic vertebræ are rudimentary.
The ligaments of the union are:-

Capsular.
Middle costo-transverse.
Superior costo-transverse.
Posterior costo-transverse.
The capsular ligament (figs. 214 and 216) forms a thin, loose, fibrous
envelope to the synovial membrane. Its fibres are attached to the bones just
beyond the articular margins, and are thickest below, where they are not strengthened
by any other structure. They are connected on the inner side with the middle,
above with the superior, and on the outer side with the posterior costo-transverse
ligaments. The eleventh and twelfth ribs are unprovided with a capsule.
The middle costo-transverse, or interosseous ligament (fig. 216), consists of
short fibres passing between the back of the neck of the rib and front of the
transverse process, with which the tubercle articulates. It extends from the
capsule of the central costo-vertebral joint to that of the costo-transverse. It is
best seen on horizontal section through the bones. In the eleventh and twelfth
ribs this ligament is rudimentary.
The posterior costo-transverse ligament (fig. 216) is a short but thick, strong,
and broad ligament, which extends outwards and upwards from the extremity of

222
THE ARTICULATIONS

the transverse process to the non-articular surface of the tubercle of the correspond-
ing rib. The eleventh and twelfth ribs have no posterior ligament.
The superior costo-transverse ligament (fig. 215) is a strong, broad band of
fibres which ascends outwards from the crest on the upper border of the neck of
the rib, to the lower border of the transverse process above. A few scattered
posterior fibres pass upwards and inwards from the neck to the transverse process.
It is best seen from the front. Its inner border bounds the foramen through
which the posterior branches of the intercostal vessels and nerves pass. To
the external border is attached the thin aponeurosis covering the external inter-
costals. Its anterior surface is in relation with the intercostal vessels and nerve;
the posterior with the longissimus dorsi. The first rib has no superior costo-
transverse ligament.
The synovial membrane (fig. 216) is a single sac.
The arterial and nerve supplies come from the posterior branches of the inter-
costal arteries and nerves.
The movements which take place at these joints are limited to a gliding of the
tubercle of the rib upon the transverse process. The exact position of the facet on
the transverse process varies slightly from above downwards, being placed higher
on the processes of the lower vertebræ. The plane of movement in most of
the costo-transverse joints is inclined upwards and backwards in inspiration,
and downwards and forwards in expiration. The point round which these
movements occur is the head of the rib, so that the tubercle of the rib glides upon
the transverse process in the circumference of a circle, the centre of which is at the
costo-central joint.
5. THE ARTICULATIONS AT THE FRONT OF THE THORAX
These may be divided into four sets, viz. :-
(a) The chondro-sternal articulations, or the junction of the costal cartilages
with the sternum.
(b) The costo-chondral joints, or the union of the ribs with their costal
cartilages.
(c) The intersternal joints, or the union of the several parts of the sternum
with one another.
(d) The interchondral joints, or the union of five costal cartilages (sixth,
seventh, eighth, ninth, and tenth) with one another.

(a) THE CHONDRO-STERNAL ARTICULATIONS
Class.-Diarthrosis.
Subdivision.-Ginglymus.
These articulations are between the lateral borders of the sternum and the ends
of the costal cartilages. The union of the first rib with the sternum is synarthrodial,
and therefore forms an exception to the others. From the second to the seventh
inclusive, the articulations have the following ligaments, which together form a
complete capsule :-
Anterior chondro-sternal.
Posterior chondro-sternal.
Superior chondro-sternal.
Inferior chondro-sternal.

The anterior chondro-sternal ligament (fig. 217) is a triangular band of
strong fibres which cover the inner half-inch of the front of the costal cartilage,
and radiate upwards and downwards upon the front of the sternum.
Some
of the fibres decussate across the middle line with fibres of the opposite ligament.
OF THE STERNUM
223
At its upper and lower borders it is in contact with the superior and inferior
ligaments respectively.
The posterior chondro-sternal ligament consists of little more than a thickening
of the fibrous envelopes of the bone and cartilage, the joint being completed behind
by a continuity of perichondrium with periosteum.
FIG. 217. THE STERNUM.
(Left side, showing ligaments; right side, the synovial cavities.)

FOR FIRST RIB
An interarticular
ligament
SECOND RIB
The plate of fibro--
cartilage between
manubrium
meso-sternum
and
THIRD RIB
FOURTH RIB
FIFTH RIB
SIXTH RIB
SEVENTH
RIB
Chondro-xiphoid ligament
Anterior
chondro-
sternal
ligament
Interchondral
capsular ligament
The superior and inferior ligaments are strong, well-marked bands, which pass
from the upper and lower borders of the costal cartilage to the lateral edges of the
sternum respectively. The sixth and seventh cartilages are so close that the
superior ligament of the seventh is blended with the inferior of the sixth rib.

224
THE ARTICULATIONS
Deeper than the fibres of these ligaments are short fibres passing from the
margins of the sternal facets to the edges of the facets on the cartilages; they are
most distinct in the front and lower part of the joint, and may encroach so much
upon the synovial cavity as to reduce it to a very small size, or almost obliterate it.
This occurs mostly in the case of the sixth and seventh joints, especially the latter.
The interarticular ligament (fig. 217) is by no means constant, but is usually
present in the second joint on one, if not on both sides of the same subject. It
consists of a strong transverse bundle of fibres passing from the ridge on the
facet on the cartilage to the symphysial substance between the manubrium and
body; sometimes the upper part of the synovial cavity is partially or entirely
obliterated by short, fine, ligamentous fibres.
The chondro-xiphoid ligament (fig. 217) is a strong flat band of fibres passing
obliquely upwards and outwards from the front surface of the xiphoid cartilage to
the anterior surface of the sternal end of the seventh costal cartilage, and most
frequently to that of the sixth also.
Synovial membranes.-The union of the first cartilage with the sternum being
synarthrodial, it has no synovial membrane; the second has usually two, separated
by the interarticular ligament. The rest usually have one synovial membrane,
which may occasionally be subdivided into two (fig. 217).
The arterial supply is derived from perforating branches of the internal
mammary; and the nerves come from the anterior branches of the intercostals.
Movements.-Excepting the first, the chondro-sternal joints are ginglymoid,
but the motion of which they are capable is very limited. It consists of a hinge-
like action in two directions: first, there is a small amount of elevation and
depression which takes place round a transverse axis; and, secondly, there is some
forward and backward movement round an obliquely vertical axis. In inspira-
tion the cartilage is elevated, and the lowest part of its articular facet is pressed
into the sternal socket, and the sternum is thrust forwards so that the upper and
front edges of the articular cartilages separate a little; in expiration the reverse
movement takes place. Thus the two extremities of the costal arches move in
their respective sockets in opposite directions.
This difference results necessarily from the fact that the costal arch moves
upon the vertebral column, and, having been elevated, it in its turn elevates the
sternum by pushing it upwards and forwards. Were this not the case, the sternum
would be depressed by the elevation of the costal arches.
The chondro-xiphoid ligament tends to prevent the xiphoid cartilage being drawn
backwards by the action of the diaphragm.
(b) THE COSTO-CHONDRAL JOINTS
Class.-Synarthrosis.
The extremity of the costal cartilage is received into a cup-shaped depression
at the end of the rib, which is somewhat larger than the cartilage. The two are
joined together by the continuity of the investing membranes, the periosteum
of the rib being continuous with the perichondrium of the cartilage, much in the
same way as the epiphyses of the bones are joined to their shafts.
(c) THE UNION OF THE SEGMENTS OF THE STERNUM WITH ONE ANOTHER
The union of the manubrium with the gladiolus may be either an amphi-
arthrodial or diarthrodial joint. In a certain number of cases there is a true
amphiarthrodial joint, with true fibro-cartilage (fig. 217) between the bones. In
other cases each segment of bone is tipped with cartilage as in diarthrodial joints.
OF THE STERNUM
225
The ligaments which connect them are really periosteum thickened by longi-
tudinal fibres, and also the radiating fibres from the chondro-sternal ligaments.
The anterior is much stronger than the posterior.
The gladiolus is joined to the xiphoid cartilage by a thick investing membrane,
by anterior and posterior longitudinal fibres, and by radiating fibres of the sixth
and seventh chondro- sternal ligaments. The chondro- xiphoid ligament also
connects the xiphoid with the anterior surface of the sixth and seventh costal
cartilages, and thus indirectly with the gladiolus; and some fine fibro-areolar
tissue also connects the xiphoid with the back of the seventh costal cartilage.
The junction of the xiphoid with the sternum is on a level somewhat posterior
to the junction of the seventh costal cartilage with the sternum. The union is
synarthrodial.
(d) THE INTERCHONDRAL ARTICULATIONS
Class.-Diarthrosis.
Subdivision.-Arthrodia.
A little in front of the point where the costal cartilages bend upwards towards
the median line, the sixth is united with the seventh, the seventh with the eighth,
the eighth with the ninth, and the ninth with the tenth.
At this point, each of the cartilages from the sixth to the ninth inclusive is
deeper than elsewhere, owing to the projection downwards from its lower edge of a
broad blunt process, which comes into contact with the cartilage next below.
Each of the apposed surfaces is smooth, and they are connected at their margins
by ligamentous tissue, which forms a complete capsule for the articulation, and is
lined by a synovial membrane. The largest of these cavities is between the
seventh and eighth; those between the eighth and ninth, and ninth and tenth, are
smaller, and are not free to play upon each other in the whole of their extent,
being held together by ligamentous tissue at their anterior margins. Sometimes
this fibrous tissue completely obliterates the synovial cavity.
The arteries are derived from the musculo-phrenic, and the nerves from the
intercostals.
Movements.-By means of the costal cartilages and interchondral joints,
strength with elasticity is given to the wall of the trunk at a part where the
cartilages are the only firm structures in its composition; while a slight gliding
movement is permitted between the costal cartilages themselves, which takes
place round an axis corresponding to the long axes of the cartilages. By this
means, the outward projection of the lower part of the thoracic wall is increased
by deep inspiration.

MOVEMENTS OF THE THORAX AS A WHOLE
Before describing these movements as a whole, it must be premised that there
are some few modifications in the movements of certain ribs resulting from their
shape. Thus the first rib (and to a less extent the second also), which is flat on
its upper and under surfaces, revolves on a transverse axis drawn through the
costo-vertebral and costo-transverse joints. During inspiration and expiration, the
anterior extremities of the first pair of costal arches play up and down, the
tubercles and the heads of the ribs acting in a hinge-like manner, the latter
having also a slight screwing motion. By this movement the anterior ends of the
costal arches are simply raised or depressed, and the sternum pushed a little for-
wards: it may be likened to the movement of a pump-handle, as in fig. 218, a, b.
The movements of the other ribs, particularly in the mid-region of the thorax,
are more complex, for, besides the elevation of the anterior extremities, the bodies
Q
226
THE ARTICULATIONS
and angles of the ribs rise nearly as much as the extremities themselves. In this
movement the tubercles of the ribs glide upwards and backwards in inspiration,
and downwards and forwards in expiration; and the movement may be likened to
that of a bucket handle, as in fig. 218, A, B.
During inspiration, the cavity of the thorax is increased in every direction.
The antero-posterior diameter is increased by the thrusting forwards of the
sternum, caused by the elevation of the costal cartilages and fore part of the ribs,
whereby they are brought to nearly the same level as the heads of the ribs. The
transverse diameter is increased: (i) Behind, by the elevation of the middle part of
the ribs; for when at rest the mid-part of the rib is on a lower level than either
the costo-vertebral or chondro-sternal articulations. Owing to this obliquity the
transverse diameter is increased when the rib is raised, and the increase is
proportionate to the degree of obliquity. (ii) By the eversion of the lower border
of the costal arch, which rolls outwards as the arch is raised. (iii) The transverse
diameter is increased in front by the abduction of the anterior extremity of the
rib at the same time as it is elevated and thrust forwards.
FIG. 218.-DIAGRAM OF AXIS OF RIB-MOVEMENT. (After Kirkes.)

a
b
B
The increase in the vertical diameter of the thorax is due to the elevation of
the ribs, especially the upper ones, and the consequent widening of the intercostal
spaces; but the chief increase in this direction is due to the descent of the
diaphragm.
The greatest increase both in the antero-posterior and transverse diameters
takes place where the ribs are longest, most oblique, and most curved at their
angles, and where the bulkiest part of the lung is enclosed. This is on a level with
the sixth, seventh, and eighth ribs.
At the lower part of the thorax, where the ribs have no relation to the lungs,
and do not affect respiration directly by their movements, it is important that
the costal arches should be thrown well outwards in order to counteract the
compression of the abdominal viscera by the contraction of the diaphragm.
By widening the lower part of the thorax during inspiration, the origin of the
muscular fibres of the diaphragm is widened, and their power is increased.

THE STERNO-CLAVICULAR
227
THE ARTICULATIONS OF THE UPPER EXTREMITY
The articulations of the upper extremity are the following:--
1. The sterno-clavicular.
2. The scapulo-clavicular union.
3. The shoulder joint.
4. The elbow joint.
5. The radio-ulnar union.
6. The radio-carpal or wrist joint.
7. The carpal joints.
8. The carpo-metacarpal joints.
9. The intermetacarpal joints.
10. The metacarpo-phalangeal joints.
11. The interphalangeal joints.
1. THE STERNO-CLAVICULAR ARTICULATION
Class.-Diarthrosis.
Subdivision.-Arthrodia.
At this joint the large inner end of the clavicle is united to the superior angle
of the manubrium sterni, the first costal cartilage also assisting to support the
clavicle. It is the only joint between the upper extremity and the trunk, and takes
part in all the movements of the upper limb. Looking at the bones, one would
say that they were in no way adapted to articulate with one another, and yet they
assist in constructing a joint of great security, strength, and importance. The
bones are nowhere in actual contact, being completely separated by an inter-
articular cartilage. The interval between the joints of the two sides varies from
one inch to an inch and a half (2.5-4 cm.). The ligaments of this joint are:-
(3) Interarticular fibro-cartilage.
(4) Rhomboid or costo-clavicular.
(1) Capsular.
(2) Interclavicular.
The capsular ligament (figs. 219-220) consists of fibres, having varying direc-
tions and being of various strength and thickness, which completely surround the
articulation, and are firmly connected with the edges of the interarticular fibro-
cartilage. The fibres at the back of the joint, sometimes styled the posterior
sterno-clavicular ligament, are stronger than those in front or below, and consist
of two sets: a superficial, passing upwards and outwards from the manubrium
sterni, to the projecting posterior edge of the inner end of the clavicle, a few being
prolonged onwards upon the posterior surface of the bone. A deeper set of
fibres, especially thick and numerous below the clavicle, which connect the inter-
articular cartilage with the clavicle and with the sternum, but do not extend from
one bone to the other. The fibres in front, the anterior sterno-clavicular ligament,
are well marked, but more lax and less tough than the posterior, and are overlaid
by the tendinous sternal origin of the sterno-mastoid, the fibres of which run
parallel to those of the ligament. They extend obliquely upwards and outwards
from the margin of the sternal facet to the anterior surface of the clavicle some
little distance from the articular margin. The fibres which cover in the joint
below are short, woolly, and consist more of fibro-areolar tissue than true fibrous
tissue; they extend from the upper border of the first costal cartilage to the lower
border of the clavicle just external to the articular margin, and fill up the gap
between it and the rhomboid ligament. The superior portion consists of short

Q 2

228
THE ARTICULATIONS
tough fibres passing from the sternum to the interarticular cartilage; and of others
welding the fibro-cartilage to the upper edge of the clavicle, only a few of them
passing from the clavicle direct to the sternum.
The interclavicular ligament (figs. 219, 220) is a strong, concave band,
materially strengthening the superior portion of the capsule. It is nearly a quarter
FIG. 219.-POSTERIOR VIEW OF THE STERNO-CLAVICULAR JOINT.
Interclavicular
ligament
Posterior
portion of
capsule
Rhomboid
ligament
of an inch (6 mm.) deep, with the concavity upwards, its upper border tapering to
a narrow, almost sharp edge. It is connected with the posterior superior angle of
the sternal extremity of each clavicle, and with the fibres which weld the inter-
articular cartilage with the clavicle; and then passes across from clavicle to clavicle
along the posterior aspect of the upper border of the manubrium sterni. The
FIG. 220.-ANTERIOR VIEW OF STERNO-CLAVICULAR JOINT.
(The capsule is cut into on the left side to show the interarticular fibro-cartilage
dividing the joint into two cavities.)
Edge of inter- Rhomboid
articular cartilage ligament
Rhomboid
ligament
Anterior
sterno-
clavicular
ligament
Inter-
clavicular
ligament
lowest fibres are attached to the sternum, and join the posterior fibres of the
capsule of each joint. In the middle line between the ligament and the sternum
there is an aperture for the passage of a small artery and vein.
The rhomboid or costo-clavicular ligament (figs. 219, 220) is a strong dense
THE STERNO-CLAVICULAR
229
band, composed of fine fibres massed together into a membranous structure.
It extends from the anterior edge of the upper border of the first costal cartilage,
upwards, backwards, and distinctly outwards to the rhomboid impression on the
under surface of the inner extremity of the clavicle, to which it is attached just
external to the lower part of the capsule. Frequently some of the outer fibres
pass upwards and inwards behind the rest, and give the appearance of decussating.
It is from half to three-quarters of an inch (1.5-2 cm.) broad.
The interarticular fibro-cartilage (figs. 220 and 221) is a flattened disc of nearly
the same size and outline as the inner articular end of the clavicle, which it fairly
accurately fits. It is attached, above to the upper border of the posterior edge of
the clavicle; and below to the cartilage of the first rib at its union with the
sternum, where it assists in forming the socket for the clavicle. At its circum-
ference it is connected with the capsular ligament, and this connection is very
strong behind, and still stronger above where it is blended with the interclavicular
ligament. It is usually thinnest below, where it is connected with the costal
cartilage. It varies in thickness in different parts, sometimes being thinner in
FIG. 221.-SECTION THROUGH STERNO-CLAVICULAR JOINT.

The interarticular
fibro-cartilage
The joint between
the sternum and
second
cartilage
costal
the centre than at the circumference, sometimes the reverse, and is occasionally
perforated in the centre. It divides the joint into two compartments.
There are two synovial membranes (figs. 220 and 221): an outer one, which is
reflected from the clavicle and capsule over the outer side of the fibro-cartilage,
and is looser than the inner; the inner is reflected from the sternum over the
inner side of the fibro-cartilage, costal cartilage, and capsule. Occasionally a
communication takes place between them.
The arterial supply is derived from branches (1) from the internal mammary;
(2) from the superior thoracic branch of the subclavian; (3) twigs of a muscular
branch often arising from the subclavian artery pass over the interclavicular notch
(4) twigs of the suprascapular artery.
The nerve-supply is derived from the nerve to the subclavius.
15
The movements permitted at this joint are various, though limited owing to
the capsular ligament being moderately tense in every position of the clavicle.
Motion takes place in nearly every direction-viz. upwards, downwards, forwards,
backwards, and in a circumductory manner. The upward and downward motions

230
THE ARTICULATIONS
occur between the clavicle and the fibro-cartilage; during elevation of the arm,
the upper edge of the clavicle with its attached fibro-cartilage is pressed into the
sternal socket, and the lower edge glides away from the cartilage; during de-
pression of the limb, the lower edge of the clavicle presses on to the cartilage,
while the rest of the articular surface of the clavicle inclines outwards, bringing
with it to a slight degree the upper edge of the fibro-cartilage. These movements
occur on an antero-posterior axis drawn through the outer compartment of the
joint. The forward and backward motions take place between the cartilage and
sternum, the clavicle with the cartilage rolling backwards upon the sternum when
the shoulder is brought forwards, and forwards when the shoulder is forced back-
wards; these movements occur round an axis drawn nearly vertically through the
sternal socket.
The interarticular cartilage serves materially to bind the bones together, and to
prevent the inward and upward displacements of the clavicle. It also forms an
elastic buffer which tends to break shocks. The capsule, by being moderately
tight, tends to limit movements in all directions, while the interclavicular ligament
is a safeguard against upward displacement during depression of the arm. The
rhomboid ligament prevents dislocation upwards during elevation of the arm, and
resists displacements backwards.
2. THE SCAPULO-CLAVICULAR UNION
The scapula is connected with the clavicle by a synovial joint with its
ligaments; and also by a set of ligaments passing between the coracoid process
and the clavicle. So that we have to consider-
(a) The acromio-clavicular articulation.
(b) The coraco-clavicular ligaments.
(c) The proper scapular ligaments are also best described in this section-viz.
the coraco-acromial and transverse.
(a) THE ACROMIO-CLAVICULAR JOINT
Class.-Diarthrosis. Subdivision.-Arthrodia.
The acromio-clavicular joint frequently contains an interarticular fibro-carti-
lage, and is surrounded by a capsular ligament.
The capsular ligament (figs. 223 and 226) completely surrounds the articular
margins, and is composed of strong, coarse fibres arranged in parallel fasciculi, of
fairly uniform thickness, which are attached to the borders as well as the surfaces of
the bones. It is somewhat lax in all positions of the joint, so that the clavicle is
not tightly braced to the acromion. The fibres extend three-quarters of an inch
(2 cm.) along the clavicle posteriorly, but only a quarter of an inch (6 mm.)
anteriorly. Superiorly, they are attached to an oblique line joining these two
points, while inferiorly they reach to the ridge for the trapezoid ligament with
which they blend. At the acromion they extend half way across the upper and
lower surfaces, but at the anterior and posterior borders of that process they are
attached close to the articular facet. The anterior fibres become blended with
the insertion of the coraco-acromial ligament. The fibres are strengthened above
by the aponeuroses of the trapezius and deltoid muscles; and all run from the
acromion to the clavicle inwards and backwards.
The interarticular fibro-cartilage is occasionally present, but is usually im-
perfect, only occupying the upper part of the joint; it may completely divide the
joint into two cavities, or be perforated in the centre. It is usually thicker at the
THE SCAPULO-CLAVICULAR
231
edge than at the centre, and some of the fibres of the capsular ligament are blended
with its edges.
The synovial membrane lining the joint is occasionally either partially or
entirely divided into two by an interarticular fibro-cartilage.
(b) THE CORACO-CLAVICULAR UNION
The coraco-clavicular ligament (figs. 222, 223, 226) consists of two parts, the
conoid and trapezoid ligaments.
The conoid ligament is the internal and posterior portion, and passes upwards
and outwards from the coracoid process to the clavicle. It is a very strong and
coarsely fasciculated band of triangular shape, the apex being fixed to the inner
FIG. 222.-ANTERIOR VIEW OF SHOULDER, SHOWING ALSO CORACO-CLAVICULAR AND
CORACO-ACROMIAL LIGAMENTS.
Conoid ligament

Trapezoid ligament
Transverse
Escapular
ligament
Coraco-acromial ligament
Short head of biceps
Subscapular tendon
Capsule of shoulder
Long tendon of
biceps
and posterior edge of the root of the coracoid process just in front of the supra-
scapular notch, some fibres joining the transverse ligament. Its base is at the
clavicle, where it widens out, to be attached to the posterior edge of the under
surface, as well as to the conoid tubercle. It is easily separated from the
trapezoid without being absolutely distinct. A small bursa often exists between
it and the coracoid process; internally, some of the fibres of the subclavius
muscle are often attached to it.
The trapezoid ligament is the anterior and outer portion. It is a strong, flat,
quadrilateral plane of closely-woven fibres, the surfaces of which look upwards and
inwards towards the clavicle, and downwards and outwards over the upper surface
of the coracoid process. At the coracoid it is attached for about an inch (2.5 cm.)
to a rough ridge which runs forwards from the angle, along the anterior border
of the process. At the clavicle, it is attached to the
oblique ridge which runs

232
THE ARTICULATIONS
outwards and forwards from the conoid tubercle, reaching as far as, and blending
with the inferior part of the acromio-clavicular ligament. Its anterior edge is free,
and overlies the coraco-acromial ligament; the posterior edge is shorter than the
anterior, and is in contact with the posterior and outer portion of the conoid
ligament.
The arterial supply is derived from the suprascapular, acromial branches of
the acromio-thoracic, and the anterior circumflex.
The nerve-supply is derived from the suprascapular and circumflex nerves.
Movements. In the movements of the shoulder girdle, the scapula moves upon
the outer end of the clavicle, and the clavicle, in turn, carried by the uniting
ligaments, moves upon the sternum; so that the entire scapula moves in the are
of a circle whose centre is at the sterno-clavicular joint, and whose radius is the
clavicle. The scapula, in moving upon the clavicle, also moves upon the thorax
forwards and backwards, upwards and downwards, and also in a rotatory direction
upon an axis drawn at right angles to the centre of the bone.. Throughout these
movements the lower angle and base of the scapula are kept in contact with the
ribs by the latissimus dorsi which straps down the former, and the rhomboids and
serratus magnus which brace down the latter. The glenoid cavity could not
have preserved its obliquely forward direction had there been no acromio-clavicular
joint, but would have shifted round a vertical axis, and thus the shoulder would
have pointed inwards when the scapula was advanced, and outwards when it was
drawn backwards. By means of the acromio-clavicular joint, the scapula can be
forcibly advanced upon the thorax, the glenoid cavity all the time keeping its face
duly forwards. Thus the muscles of the shoulder and forearm can be with
advantage combined, as, for example, in giving a direct blow. The acromio-
clavicular joint also permits the lower angle of the scapula to be retained in contact
with the chest wall during the rising and falling of the shoulder, the scapula
turning in a hinge-like manner round the horizontal axis of the joint.
There are no actions in which the scapula moves on a fixed clavicle, or the
clavicle on a fixed scapula; the two bones, bound together by their connecting
ligament, must move in unison.
(c) THE PROPER SCAPULAR LIGAMENTS
There are three proper ligaments of the scapula, which pass between different
portions of the bone, viz.-
Coraco-acromial.
Inferior transverse.
Transverse.
The coraco-acromial ligament (figs. 222, 226) is a flat, triangular band with a
broad base, attached to the outer border of the coracoid process, and a blunt apex
which is fixed to the tip of the acromion. It is made up of two broad marginal
bands, and a smaller and thinner intervening portion. The anterior band, which
arises from the anterior portion of the coracoid process, is the stronger, and some of
its marginal fibres can often be traced into the short head of the biceps, which can
then make tense this edge of the ligament. The posterior band, coming from the
posterior part of the coracoid process, is also strong. The intermediate part, of
variable extent, is thin and membranous, containing but few ligamentous fibres;
it is often incomplete near the coracoid process, leaving a small gap. The superior
surface of the ligament looks upwards and a little forwards, and is covered by the
deltoid muscle; the inferior looks downwards and a little backwards, and is
separated from the capsule of the shoulder-joint by a bursa. At the coracoid
process it overlies the coraco-humeral ligament. It is barely one-third of an inch

THE SCAPULO-CLAVICULAR
233
(8 mm.) above the capsule of the shoulder, and in the undissected state there is
scarcely a quarter of an inch (6 mm.) interval. The outer edge projects over the
centre of the head of the humerus, and is continued into a tough fascia under the
deltoid; the inner edge is continuous with the fascia over the supra-spinatus
muscle. It binds the two processes firmly together, and so strengthens each;
it holds the deltoid off the capsule of the shoulder, and protects the joint from
slight injuries directed downwards and backwards against it.
The transverse, coracoid, or suprascapular ligament (figs. 222, 223, 224) is a
small triangular band of fibrous tissue, the surfaces of which look forwards and
backwards; and its edges, which are thin and sharp, are turned upwards and down-
FIG. 223.-POSTERIOR VIEW OF THE SHOULDER JOINT, SHOWING ALSO THE ACROMIO-
CLAVICULAR JOINT AND THE PROPER LIGAMENTS OF THE SCAPULA.
Conoid ligament
Acromio-clavicular
ligament
Tendon of infra-
spinatus and teres
minor
Inferior transverse
or spino-glenoid
ligament
Capsule of shoulder
Tranverse ligament

wards. It continues the superior border of the scapula, bridging over the supra-
scapular notch. It is broader internally, where it springs from the upper border
of the scapula on its dorsal surface; and narrow externally, where it is attached
to the base of the coracoid process; some of its fibres are inserted under the edge
of the trapezoid ligament, and others pass upwards with the conoid to reach the
clavicle. The suprascapular artery passes over it, and the suprascapular nerve
beneath it. Internally, some fibres of the omo-hyoid muscle arise from it.
The inferior transverse or spino-glenoid ligament (fig. 223) reaches from the
external border of the spine to the margin of the glenoid cavity, and so forms a
foramen under which the suprascapular vessels and nerve gain the infraspinous
fossa. It is usually a weak membranous structure with but few ligamentous
fibres.

234
THE ARTICULATIONS
3. THE SHOULDER JOINT
Subdivision.
Enarthrodia.
Class.--Diarthrosis.
The shoulder is one of the most perfect, and most movable of joints, the large
upper end of the humerus playing upon the shallow glenoid cavity. Like the hip,
it is a ball-and-socket joint. It is retained in position much less by ligaments
than by muscles and the effects of atmospheric pressure; and, owing to the looseness
of its capsule, as well as to all the other conditions of its construction and
position, it is exceedingly liable to be displaced; on the other hand, it is sheltered
from violence by the two projecting processes-the acromion and coracoid.
The ligaments of the shoulder joint are:-
Capsular.
Gleno-humeral.
Coraco-humeral.
Glenoid.
FIG. 224.-VERTICAL SECTION THROUGH THE SHOULDER JOINT TO SHOW THE
GLENO-HUMERAL LIGAMENT.
(The joint is opened from behind.)

Supra-spinatus
muscle
Subacromial bursa
Tendon of biceps
with gleno-hume-
ral ligament
Tendon of subsca-
pularis
Capsular ligament
Glenoid ligament or fibro-cartilage
Capsular ligament

The capsular ligament (figs. 222, 223 and 224) is a loose sac, insufficient in
itself to maintain the bones in contact. It consists of fairly distinct but not coarse
fibres, closely woven together, and directed, some straight, others obliquely, between
the two bones, a few circular ones being interwoven amongst them. At the
scapula, it is fixed on the dorsal aspect to the prominent rough surface of the
glenoid process, reaching as far as the neck of the bone. Above, it is attached
to the root of the coracoid process in front, to the ventral surface of the glenoid
process, at a variable distance from the articular margin, often reaching half an
inch (12 mm.) upon the neck of the bone, and thus allowing the formation of a
pouch; it may not, however, extend for more than a quarter of an inch (6 mm.)
beyond the articular margin: below, it blends with the origin of the long head of
the triceps. At the humerus, the upper half is fixed to the anatomical neck,
sending a prolongation downwards between the two tuberosities which attenuates
THE SHOULDER JOINT
235
as it descends, and covers the transverse humeral ligament. The lower half of the
capsule descends upon the humerus further from the articular margin, some of the
deeper fibres being reflected upwards so as to be attached close to the articular
edge, thus forming a kind of fibrous investment for the neck of the humerus.
This ligament is more uniform in thickness than that of the hip.
Gleno-humeral bands of the capsule (figs. 224 and 225).-There are three
accessory bands which strengthen the capsule, two of which are seen superficially,
and consist of a few strengthening fibres, one on the inner aspect reaching from
the glenoid cavity to the lower border of the lesser tuberosity along the lower border
of the subscapularis tendon; and the inferior reaching from the under part of the
glenoid cavity to the under part of the neck of the humerus. The third, the superior
band, is known as the gleno-humeral ligament, and can only be seen after opening
the capsule. It runs from the edge of the glenoid cavity at the root of the coracoid,
just internal to the origin of the long tendon of the biceps, and, passing inwards
and downwards at an acute angle to the tendon, for which it forms a slight groove
or sulcus, is fixed to the lesser tuberosity of the humerus. It is a thin, ribbon-
like band, of which the upper surface is attached to the capsule, while the other
FIG. 225.-FETAL SHOULDER JOINT, SHOWING THE GLENO-HUMERAL LIGAMENT,
AND ALSO THE SHORT HEAD OF THE BICEPS, BEING CONTINUOUS WITH THE
CORACO-ACROMIAL LIGAMENT.

Short tendon of biceps
running on into anterior
band of coraco-acromial
ligament
-Long tendon of biceps
Gleno-humeral ligament
Capsule of shoulder, turned
back
Subscapularis tendon, cut
and turned outwards
is free and turned towards the joint. In the foetus it is often, and in the adult
occasionally, quite free from the capsule, and may be as thick as the long tendon
of the biceps (fig. 225).
The tendons of the supra- and infra-spinatus, teres minor, and subscapularis
muscles strengthen and support the capsule, especially near their points of
insertion, and can be with difficulty dissected off from it. The long head of the
triceps supports and strengthens the capsule below. The capsule also receives an
upward slip from the pectoralis major. The supra-spinatus often sends a slip into
the capsule from its upper edge.
The coraco-humeral ligament (fig. 226) is a strong broad band, which is attached
above to the outer edge of the root and horizontal limb of the coracoid nearly as far
as the tip. From this origin it is directed backwards to blend with the capsule
along the line of the biceps tendon, and is inserted into the greater tuberosity of the
humerus. Seen from the back, it looks like an uninterrupted continuation of
the capsule, while from the front it looks like a fan-shaped prolongation over-
lying the rest of the ligament. At its origin there is sometimes a bursa between
it and the capsule.
The glenoid ligament (figs. 224 and 227) is a narrow rim of dense fibro-cartilage,
which surrounds the edge of and deepens the glenoid socket. It is about a quarter


236
THE ARTICULATIONS
of an inch (6 mm.) wide above and below, but less at the sides. Its outer edge is
inseparably welded, near the bone, with the capsular ligament. In some places,
especially at the inner side and above, it often overlaps the cartilage and forms a
fringe; at others, it may be separated by a very narrow interval, covered by loosely
woven fibro-cartilage. Its structure is almost entirely fibrous, with but few
cartilage cells intermixed. At the upper part of the fossa the biceps tendon is
prolonged into the glenoid ligament, the tendon usually dividing and sending
fibres into both sides of the ligament, which may wind round nearly the whole
circumference of the socket. It may, however, send fibres into one side only,
usually into the outer.
The articular cartilage covering the glenoid fossa is thicker at the circum-
ference than at the centre, thus tending to deepen the cavity. It is usually
thickest at the lower part of the fossa; over the head of the humerus the cartilage
is thickest at and below the centre.
FIG. 226.--OUTER VIEW OF THE SHOULDER JOINT, SHOWING THE CORACO-HUMERAL
AND TRANSVERSE HUMERAL LIGAMENTS.
Trapezoid ligament-
Capsule of the acromio-
clavicular joint
Coraco-acromial ligament
Coraco-humeral ligament
Tendon of subscapularis muscle-
Transverse humeral ligament
Tendon of biceps
The synovial membrane lines the glenoid ligament, and is then reflected over
the capsule as far as its attachment to the humerus, from which it ascends as
far as the edge of the articular cartilage. The tendon of the biceps receives a
long tubular sheath, which is continuous with the synovial membrane, both at its
attached extremity and at the bicipital groove, but is free in the rest of its extent.
The synovial cavity sometimes communicates with the bursa under the subscapu-
laris, and less frequently with one under the infraspinatus muscle. It also sends
a pouch-like prolongation beneath the coracoid process when the fibrous capsule is
attached wide of the margin of the glenoid fossa. A few fringes are seen near the
edge of the glenoid cavity, and there is often one which runs down the inner edge
of the biceps tendon, extending slightly below it, and so making a slight groove
for
the tendon to lie in.
THE SHOULDER JOINT
237
The transverse humeral ligament (fig. 226) is so closely connected with the
capsule of the shoulder that, although it is a proper ligament of the humerus, it
may
well be described here. It is a strong band of fibrous tissue, which extends
between the two tuberosities, roofing in the bicipital canal. It is covered by a thin
expansion of the capsule. It is limited to the portion of the bone above the
line of the epiphysis. (C. Gordon Brodie, Journ. Anat. xxiv. 247.)
The following muscles are in relation with the capsular ligament: above, the
supraspinatus; externally, the infraspinatus and teres minor; below, the long
head of the triceps; internally, the tendon of the subscapularis. The deltoid
covers the outer and upper surfaces of the joint, but is separated from the capsule
by a bursa, and the tendons of the short rotator muscles. An upward slip from
the pectoralis major joins the capsule below. Internally are the long tendon of the
biceps and the gleno-humeral ligament.
FIG. 227.-BICEPS TENDON, BIFURCATING AND BLENDING ON EACH SIDE WITH
THE GLENOID FIBRO-CARTILAGE.

Tendon of biceps
Tendon of biceps blended
with glenoid ligament
The arterial supply is derived from the suprascapular, anterior and posterior
circumflex, subscapular, dorsalis scapulæ, and a branch from the second portion of
the axillary artery.
The nerve-supply is derived from the suprascapular, by branches in both fossæ ;
and from the circumflex and subscapular nerves.
The movements of the shoulder joint consist of flexion, extension, adduction
and abduction, rotation and circumduction.
Flexion is the swinging forwards, extension the swinging backwards, of the
humerus; abduction is the raising of the arm from, and adduction depression of
the arm to, the side. In flexion and extension the head of the humerus moves upon
the centre of the glenoid fossa round an oblique line corresponding to the axis of
the head and neck of the humerus, flexion being more free than extension, and in
extreme flexion the scapula follows the head of the humerus, so as to keep the
articular surfaces in apposition. In extension the scapula moves much less, if at all.
In abduction and adduction the scapula is fixed, and the humerus rolls up and
down upon the glenoid fossa; during abduction the head descends until it projects
beyond the lower edge of the glenoid cavity, and the great tuberosity impinges
against the arch of the acromion; during adduction, the head of the humerus

238
THE ARTICULATIONS
ascends in its socket, the arm at length reaches the side, and the capsule is com-
pletely relaxed.
In circumduction, the humerus, by passing quickly through these movements,
describes a cone, whose apex is at the shoulder joint, and the base at the distal
extremity of the bone or limb.
Rotation takes place round a vertical axis drawn through the extremities of the
humerus from the centre of the head to the inner condyle; in rotation forwards
(that is, inwards) the head of the bone rolls back in the socket as the great tuberosity
and shaft are turned forwards; in rotation backwards (that is, outwards) the head
of the bone glides forwards, and the tuberosity and shaft of the humerus are turned
backwards, i.e. outwards.
Great freedom of movement is permitted at the shoulder, and this is increased
by the mobility of the scapula. Restraint is scarcely exercised at all upon the
movements of the shoulder by the ligaments, but chiefly by the muscles of the
joint.
In abduction, the lower part of the capsule is somewhat, and in extreme
abduction considerably, tightened; and in rotation inwards and outwards, the
upper part of the capsule is made tense, as is also, in the latter movement, the
coraco-humeral ligament.
The movements of abduction and extension have a most decided and definite
resistance offered to them other than by muscles and ligaments, for the great
tuberosity of the humerus, by striking against the acromion process and coraco-
acromial ligament, stops short any further advance of the bone in these directions,
and thus abduction ceases altogether as soon as the arm is raised to a right angle
with the trunk, and extension shortly after the humerus passes the line of the
trunk.
Further elevation of the arm beyond the right angle is effected by the rotation
of the scapula round its own axis by the action of the trapezius and serratus
magnus muscles upon the sterno-clavicular and acromio-clavicular joints.
The acromion and coracoid processes, together with the coraco-acromial ligament,
form an arch, which is separated by a bursa and the tendon of the supra-spinatus
from the capsule of the shoulder. Beneath this arch the movements of the joint
take place, and against it the head and tuberosities are pressed when the weight of
the trunk is supported by the arms; the greater tuberosity and the upper part of the
shaft impinge upon it when abduction and extension are carried to their fullest
extent.
No description of the shoulder joint would be complete without a short notice.
of the peculiar relation which the biceps tendon bears to the joint. It passes over
the head of the humerus a little to the inner side of its summit, and lies free
within the capsule, surrounded only by a tubular process of synovial membrane.
It is flat, with the surfaces looking upwards and downwards, until it reaches the
bicipital groove, when it assumes a rounded form. It strengthens the articulation
along the same course as the coraco-humeral ligament, and tends to prevent the
head of the humerus being pulled upwards too forcibly against the under surface of
the acromion. It also serves the purpose of a ligament by steadying the head of
the humerus in various movements of the arm and forearm, and to this end is let
into a groove at the upper end of the bone, from which it cannot escape on account
of the abutting tuberosities and the strong transverse humeral ligament which
binds it down. Further, it acts like the four shoulder muscles, which pass over the
capsule to keep the head of the humerus against the glenoid socket; and, more-
over, it resists the tendency of the pectoralis major and latissimus dorsi muscles, in
certain actions when the arm is away from the side of the body, to pull the head of
the humerus below the lower edge of the cavity.
THE ELBOW JOINT
239
4. THE ELBOW JOINT
Class.-Diarthrosis.
Subdivision. Ginglymus.
The elbow is a complete hinge, and, unlike the knee, depends for its security
and strength upon the configuration of its bones rather than on the number,
strength, or arrangement of its ligaments. The bones composing it are the lower
end of the humerus above, and the upper ends of the radius and ulna below; the
articular surface of the humerus being received partly within the great sigmoid
cavity of the ulna, and partly upon the cup-shaped surface of the radius. The
ligaments form one large and capacious capsule, which, by blending with the
orbicular ligament, and then passing on to be attached to the neck of the radius,
embraces the elbow and the superior radio-ulnar joints, uniting them into one.
Laterally, it is considerably strengthened by superadded fibres arising from the
condyles of the humerus and inseparably connected with the capsule. For con-
venience of description it will be spoken of as consisting of four portions :--
Anterior.
Posterior.
Internal.
External.
The anterior portion (fig. 228) is attached to the front of the humerus above
the articular surface and coronoid fossa, in an inverted V-shaped manner, to two
very faintly marked ridges which start from the front of the internal and external
condyles, and meet at a variable distance above the coronoid fossa. Below, it is
fixed, just beyond the articular margin, to the front of the coronoid process; it is
intimately blended with the front of the orbicular ligament, a few fibres passing
on to the neck of the radius. It varies in strength and thickness, being some-
times so thin as barely to cover the synovial membrane; at others, thick and strong,
and formed of coarse decussating fibres, the majority of which descend from the
inner side outwards to the radius.
The posterior portion (fig. 229), thin and membranous, is attached superiorly
to the humerus, in much the same inverted V-shaped way as the anterior;
ascending from the internal condyle, along the inner side of the olecranon fossa
nearly to the top; then, crossing the bottom of the fossa, it descends on the outer
side, skirting the outer margin of the trochlear surface, and turns outwards along
the posterior edge of the capitellum. Inferiorly, it is attached to a slight groove
along the superior and external surfaces of the olecranon, and the rough surface of
the ulna just beyond the lesser sigmoid notch, and with the orbicular ligament, a
few fibres passing on to the neck of the radius. It is composed of decussating
fibres, most of which pass vertically or obliquely downwards, a few taking a
transverse course at the summit of the olecranon fossa where the ligament is
usually thinnest.
The internal portion (fig. 228) is thicker, stronger, and denser than either the
anterior or posterior portions. It is triangular in form, its apex being attached to
the anterior and under aspect of the internal condyle, and to the condyloid edge of
the groove between the trochlea and the condyle. The fibres radiate downwards.
from this attachment, the anterior passing forwards to be fixed to the rough over-
hanging inner edge of the coronoid process; the middle descend less obliquely to a
ridge running between the coronoid and olecranon processes, while the posterior
pass obliquely backwards to the inner edge of the olecranon just beyond the
articular margin.
The anterior fibres are the thickest, strongest, and most

pronounced.
The external portion (fig. 229) is attached above to the lower part of the
external condyle, and from this the fibres radiate to their attachment into the
outer side of the orbicular ligament, a few fibres being prolonged to reach the

240
THE ARTICULATIONS
neck of the radius. The anterior fibres reach further forwards than the posterior
do behind. It is strong and well-marked, but less so than the internal portion.
The synovial membrane lines the whole of the capsule, and extends into the
superior radio-ulnar joint, lining the orbicular ligament.
Outside the synovial
membrane, but inside the capsule, are often seen some pads of fatty tissue; one is
FIG. 228.-INTERNAL VIEW OF THE ELBOW JOINT.
Anterior
ligament
Internal
lateral
ligament
FIG. 229.-EXTERNAL VIEW OF THE ELBOW JOINT.
Orbicular
ligament
Tendon
of biceps
-Oblique
ligament
Upper edge
of inter-
Osseous
membrane
Orbicular ligament
External lateral
ligament
Posterior ligament
situated on the inner side at the base of the olecranon, another is seen on the
outside projecting into the cavity between the radius and ulna; this latter, with a
fold of synovial membrane opposite the front of the outer lip of the trochlea,
suggests the division of the joint into two parts-one internally for the ulna, and
another externally for the radius. There are also pads of fatty tissue at the bottom
of the olecranon and coronoid fossæ, and at the tip of the olecranon process.
THE ELBOW JOINT
241
The arterial supply is derived from each of the vessels forming the free
anastomosis round the elbow, and there is also a special branch to the front and
outer side of the joint from the brachial artery, and the arterial branch to the
brachialis anticus also feeds the front of the joint.
The nerve-supply comes from the musculo-cutaneous chiefly; the ulna, median,
and musculo-spiral also give filaments to the joint.
The movements permitted at the elbow are those of a true hinge joint, viz.
flexion and extension. These movements are oblique, so that the forearm is
inclined inwards in flexion, and outwards in extension; they are limited by the
contact respectively of the coronoid and olecranon processes of the ulna with their
corresponding fossa on the humerus, and their extent is determined by the relative
proportion between the length of the processes and depth of the fosse which
receive them, rather than by the tension of the ligaments, or the bulk of the soft
parts over them. The anterior and posterior portions of the capsule, together with
the corresponding portions of the lateral ligament, are not put on stretch during
flexion and extension; but, although they may assist in checking the velocity, and
thus prevent undue force of impact, they do not control or determine the extent of
these movements. The limit of extension is reached when the ulna is nearly in a
straight line with the humerus; and the limit of flexion when the ulna describes
an angle of from 30° to 40° with the humerus.
The obliquity of these movements is due to the outward inclination of the
upper and back part of the trochlear surface, and the greater prominence of the
inner lip of the trochlea below; thus the plane of motion is directed from behind
inwards and forwards, and carries the hand towards the middle third of the
clavicle. The obliquity of the joint, the inward twist of the shaft of the humerus,
and the backward direction of its head, all tend to bring the hand towards the mid
line, under the immediate observation of the eye, either for defence, employ-
ment, or nourishment. This is in striking contrast to the lower limb, where the
direction of the foot diverges from the median axis of the trunk, thus preventing
awkwardness in locomotion. In flexion and extension, the cup-like depression
of the radial head glides upon the capitellum, and the inner margin of the
radial head travels in the groove between the capitellum and the trochlea. This
allows the radius to rotate upon the humerus while following the ulna in all its
movements. In full extension and supination, the head of the radius is barely
in contact with the inferior surface of the capitellum, and projects so much back-
wards that its posterior margin can be felt as a prominence at the back of the
elbow. In full flexion the anterior edge of the radial head is received into, and
checked against, the depression above the capitellum; while in mid-flexion the
cup-like depression is fairly received upon the capitellum, and in this position,
the radius being more completely steadied by the humerus than in any other,
pronation and supination take place most perfectly.

5. THE UNION OF THE RADIUS WITH THE ULNA
The radius is firmly united to the ulna by two joints, and an intermediate
fibrous union, viz.-
(a) The superior radio-ulnar,-whereat the head of the radius rotates within
the lesser sigmoid cavity and orbicular ligament.
(b) The union of the shafts,--the mid radio-ulnar union.
(c) The inferior radio-ulnar, whereat the lower end of the radius rolls round
the head of the ulna.
R

242
THE ARTICULATIONS
(a) THE SUPERIOR RADIO-ULNAR JOINT
Class.-Diarthrosis.
Subdivision. Trochoides.
The bones which enter into this joint are, the ulna by its lesser sigmoid cavity,
and the radius by the smooth vertical border or rim on its head. There is but one
ligament special to the joint, viz.:-
Orbicular.
The orbicular ligament consists of bands of strong fibres, somewhat thicker
than the capsule of the elbow-joint, which encircle the head of the radius,
retaining it against the side of the ulna. The bulk of these fibres forms about
three-fourths of a circle, and they are attached to the anterior and posterior
margins of the lesser sigmoid cavity; some few are continued round below the
lesser sigmoid cavity, and form a complete ligamentous circle. The ligament is
inseparably connected along its upper edge and external (i.e. its non-articular)
FIG. 230.-ORBICULAR LIGAMENT.
(The head of the radius removed to show the membranous connection of this
ligament with the radius.)

-Capsule of elbow joint
Cushion of fatty tissue
Membranous tissue joining
the orbicular ligament to
the neck of the radius
-RADIUS
Orbicular ligament
-Capsule of elbow
20
surface with the anterior, posterior, and external portions of the capsule of the
elbow, a few of the fibres of these portions, especially of the external, descending
to be attached to the neck of the radius. The lower part of the articulation
is covered in by a thin independent membranous layer, which passes from the
lower edge of the orbicular ligament to the neck of the radius, strengthened on
the outer side by those fibres passing down from the capsule. They are loose
enough to allow the bone to rotate upon its own axis (fig. 230).
The synovial membrane is the same as that of the elbow, and, after lining the
orbicular ligament, passes on to the neck of the radius, and thence up to the
articular cartilage.
The arterial and nerve-supply are the same as those to the outer part of the
elbow joint.
(b) THE MID RADIO-ULNAR UNION
There are two interosseous ligaments which pass between the shafts of the
bones and unite them firmly together, viz. :-
Oblique ligament.
Interosseous membrane.
OF THE RADIUS WITH THE ULNA
243
The oblique ligament (fig. 228) is a fairly strong, narrow band, which passes
from the lower end of the rough outer border of the coronoid process, downwards
and outwards to be attached to the posterior edge of the lower end of the
bicipital tuberosity of the radius and the vertical ridge running from it to the
inner border of the bone. Some of its fibres blend with the fibres of insertion of
the biceps tendon; behind, it is in close contact with the supinator brevis; below,
a thin membrane passes off from it to the upper edge of the interosseous mem-
brane; the posterior interosseous vessels pass in the space between it and the
interosseous membrane.
The interosseous membrane (fig. 228) is attached to the ulna at the lowest
part of the ridge in front of the depression for the supinator brevis, and along
the whole length of the interosseous border as far as the inferior radio-ulnar
articulation, approaching the front of the bone in the lower part of its attach-
ment. To the radius it is attached along the interosseous border, from an inch
(2.5 cm.) below the bicipital tuberosity to the sigmoid notch for the lower end of
the ulna. It is strongest and broadest in the centre, where the fibres are dense
and closely packed; it is also well marked beneath the pronator quadratus, and
thickens considerably at the lower end, forming a strong band of union between
the two bones. Its fibres pass chiefly downwards and inwards, from the radius
to the ulna, though some take the opposite direction; at the lower end some
are transverse. On the posterior surface are one or two bands, which pass down-
wards and outwards from the ulna to the radius, and frequently there is a strong
bundle as large as the oblique ligament; this should be called the inferior oblique
ligament (fig. 234), and it stretches from the ulna, an inch and a half above its
lower extremity, downwards and outwards to the ridge above and behind the sigmoid
notch of the radius.
At its attachment to the bones the interosseous membrane blends with the
periosteum. Its upper border is connected with the oblique ligament by a thin
membrane, which is pierced by the posterior interosseous vessels; and the lower
border, which stretches across between the two bones just above the inferior radio-
ulnar articulation, assists in completing the capsule of that joint. Its anterior
surface is in relation with the flexor profundus digitorum and flexor longus pollicis
in the upper three-quarters, the lower fourth being in relation with the pronator
quadratus. The anterior interosseous vessels and nerve descend along the
middle of the membrane, the artery being bound down to it. About an inch
from the lower end, it is pierced by the anterior interosseous artery. The posterior
surface is in relation with the supinator brevis, extensor ossis metacarpi, extensor
primi, extensor secundi internodii pollicis, and the extensor indicis; also, with the
posterior branch of the anterior interosseous artery.
(c) THE INFERIOR RADIO-ULNAR JOINT
Class.-Diarthrosis.
Subdivision.-Lateral Ginglymus.
This is, in one respect, the reverse of the superior; for the radius, instead of
presenting a circular head to rotate upon the facet on the ulna, presents a concave
facet which rolls round the ulna. The articulation may be said to consist of two
parts at right angles to one another: one between the radius and ulna, and the
other between the ulna and triangular fibro-cartilage.

The ligaments are:-
Anterior radio-ulnar.
Posterior radio-ulnar.
Triangular fibro-cartilage.
The triangular fibro-cartilage (figs. 234, 235) assists the radius in forming
an arch under which is received the first row of carpal bones. Its base is attached
R 2

244
THE ARTICULATIONS
to the margin of the radius, separating the sigmoid cavity from the articular
surface for the radio-carpal joint, while its apex is fixed from the front to the back
of the fossa at the base of the styloid process of the ulna. It gradually and
uniformly diminishes in width from base to apex, becoming rounded where it is
fixed to the ulna; it is joined by fibres of the internal lateral ligament of the wrist.
It is about three-eighths of an inch (1 cm.) wide, and the same from base to apex;
thicker at the circumference than at the centre; smooth and concave above to
adapt itself to the ulna, and smooth and slightly concave below to fit over the
cuneiform bone. Its anterior and posterior borders are united to the anterior
and posterior radio-ulnar and radio-carpal ligaments. It is the most important
structure in the inferior radio-carpal articulation, as it is a very firm bond of
union between the lower ends of the bones, and serves to limit their movements
upon one another more than any other structure in either the upper or lower
radio-ulnar joints. Its structure is fibrous at the circumference, while at the
centre there is a preponderance of cells. It differs from all other fibro-cartilages
in entering into two distinct articulations; and separates entirely the synovial
membrane of the radio-ulnar joint from that of the wrist.
The anterior radio-ulnar ligament (fig. 231) is attached by one end to the
anterior edge of the sigmoid cavity of the radius, and by the other to the rough
bone above the articular surface of the ulna as far inwards as the notch, as well as
into the anterior margin of the triangular cartilage from base to apex.
The posterior radio-ulnar ligament (fig. 232) is similarly attached to the pos-
terior margin of the sigmoid cavity at one end, and by the other to the rough
bone above the articular surface of the extremity of the ulna as far inwards as the
groove for the flexor carpi ulnaris, with the sheath of which it is connected, and
also into the whole length of the posterior margin of the triangular fibro-cartilage.
Both the radio-ulnar ligaments consist of thin, almost scattered, fibres, but they
serve to form a capsule for the support and protection of the synovial membrane.
The lower end of the interosseous membrane extends between the ulna and
radius immediately above their points of contact. Transverse fibres between the
two bones form a sort of arch above the concave articular facet of the radius,
and, joining the anterior and posterior radio-ulnar ligaments, complete the capsule
of the inferior radio-ulnar joint.
The synovial membrane, sometimes called the membrana sacciformis, is large
and loose in proportion to the size of the joint. It is not only interposed between
the radial and ulnar articular surfaces, but lines the terminal articular surface of
the ulna and the upper surface of the triangular fibro-cartilage.
The arterial supply is derived from the anterior interosseous artery, and branches
of the anterior carpal arch.
The nerve-supply comes from the anterior interosseous of the median, and the
posterior interosseous branch of the musculo-spiral.
The movements of the radius.-The upper end of the radius rotates around
an axis drawn through its own head and neck within the collar formed by the lesser
sigmoid cavity and the orbicular ligament, while the lower end rolls round the
head of the ulna, being retained in position by the triangular ligament. This rotation
is called pronation when the radius from a position nearly parallel to the ulna
turns inwards so as to lie obliquely across it; and supination when the radius turns
back again from within outwards, so as to uncross and lie nearly parallel with the
ulna. In these movements, the radius carries with it the hand, which rotates on an
axis passing a little to the inner side of the middle line; thus, the hand when pro-
nated, lies with its dorsum upwards, as in playing the piano, while when supinated,
the palm lies upwards-the attitude of a beggar asking alms. Ward thus expresses
the relations of the two extremities of the radius in pronation and supination: The
head of the radius is so disposed in relation to the sigmoid cavity at the lower end

OF THE RADIUS WITH THE ULNA
245
that the axis of the former if prolonged falls upon the centre of the circle of which
the latter is a segment; the axis thus passes through the lower end of the ulna at
a point at which the triangular fibro-cartilage is attached, and if prolonged further
passes through the ring finger. Thus the radius describes, in rotating, a blunt-
topped cone whose apex is the centre of the radial head, and whose base is at the
wrist; thus partial rotation of the bone is unaccompanied by any hinge-like or
antero-posterior motion of its head, and pronation and supination occur without
disturbance to the parallelism of the bones at the superior radio-ulnar joint.
Associated with this rotation in the ordinary way, there is some rotation of the
humero-ulnar shaft, which causes lateral shifting of the hand from side to side;
thus, with pronation there is some abduction, and with supination some adduction
combined, so that the hand can keep on the same superficies in both pronation and
supination. The power of supination in man is much greater than pronation,
owing to the immense power and leverage obtained by the curve of the radius,
and by the attachment of the biceps tendon to the back of the tubercle. For this
reason all our screw-driving and boring tools are made to be used by supination
movements.
In the undissected state, the amount of rotation it is possible to obtain is about
135°, so that neither the palm nor the fore part of the lower end of the radius can
be turned completely in opposite directions; yet in the living subject this amount
can be greatly increased by rotation of the humero-ulnar shaft at the shoulder joint.
Pronation is checked in the living subject by the posterior inferior radio-ulnar
ligament, which is strengthened by the connection of the sheath of the extensor
tendons with it; by the lowermost fibres of the interosseous membrane, the back
part of the internal and adjacent fibres of the posterior ligament of the wrist, and
the meeting of the soft parts on the front of the forearm.
Supination is checked mainly by the internal lateral ligament of the wrist, but
partly also by the oblique radio-ulnar ligament, the anterior inferior radio-ulnar,
and by the lowest fibres of the interosseous membrane.
The interosseous membrane serves, from the direction of its fibres downwards
and inwards from the radius to the ulna, to transmit the weight of the body from
the ulna to the radius in the extended position of the elbow, as in pushing forwards
with the arms extended, or in supporting one's own weight on the hands, the ulna
being in firm contact with the humerus, but scarcely at all with the carpus; while
the radius is scarcely in contact with the humerus, but in firm contact with the
carpus. Hence the weight transmitted by the ulna is communicated to the radius
by the tightening of the interosseous membrane. Conversely, in falls upon the hand
with the arm extended, the interosseous membrane acts as a sling to break the
violence of the shock, and prevents the whole force of the impact expending itself
directly upon the capitellum.

6. THE RADIO-CARPAL ARTICULATION
Class.-Diarthrosis.
Subdivision. Ginglymus (with double
hinge joint action.)
The wrist joint is formed by the union of the radius and triangular fibro-car-
tilage above, articulating with the scaphoid, semilunar, and cuneiform bones below;
the ulna being excluded by the intervention of the triangular fibro-cartilage. The
radius and triangular cartilage together present a smooth surface, slightly concave
both from before backwards, and from side to side; whilst the three bones of the
carpus present a smooth, convex surface, made uniformly even by the interosseous
ligaments which bind them together.


246
THE ARTICULATIONS
The capsule of the wrist joint has been usually described as four separate liga-
ments, and it will be convenient for the sake of a complete description to follow
this method; but it must be understood that these four portions are continuous
around the joint, extending from styloid process to styloid process on both its
aspects.
The four portions are:-
Anterior radio-carpal.
Posterior radio-carpal.
Internal lateral.
External lateral.
The anterior radio-carpal (fig. 231) is a thick strong ligament, attached
superiorly to the radius immediately above the margin of the terminal articular
facet, to the curved ridge at the root of the styloid process of the radius, and to the
anterior margin of the triangular cartilage, blending with some fibres of the capsule
FIG. 231.-ANTERIOR VIEW OF WRIST.
Anterior radio-ulnar
ligament
Internal lateral liga-
ment of wrist
Flexor carpi ulnaris
External lateral
ligament of wrist
Anterior radio-carpal
ligament
Tendon of flexor carpi
radialis
Capsular ligament of
first carpo-metacarpal
joint
of the inferior radio-ulnar joint. It passes downwards and inwards to be attached
to both rows of carpal bones, especially the second, and to the anterior intercarpal
ligament. The strongest and most oblique fibres arise from the root of the styloid
process of the radius, and pass obliquely over the scaphoid, with which only a few
fibres are connected, to be inserted into the semilunar, magnum, and cuneiform bones.
Another set, less oblique, pass from the margin of the facet for the semilunar to be
attached to the adjacent parts of the magnum, unciform, and the cuneiform bones.
Between the two sets of fibres, small vessels pass into the joint.
The posterior radio-carpal ligament (fig. 232) is attached superiorly to the
dorsal edge of the lower end of the radius, the back of the styloid process, and the
posterior margin of the fibro-cartilage. It passes downwards and inwards to be
connected with the first row of the carpal bones, chiefly with the semilunar and
cuneiform, and the posterior intercarpal ligament. This ligament is thin and
membranous, and is strengthened by (i) strong fibres passing from the back of the
fibro-cartilage, where they are blended with the posterior inferior radio-ulnar
THE RADIO-CARPAL
247
ligament, and, from the edge of the radius just behind the lesser sigmoid fossa, to
the cuneiform bone; (ii) from the ridge and groove for the extensor secundi
internodii pollicis to the back of the semilunar and cuneiform bones; and (iii) from
the groove for the radial extensors to the back of the scaphoid and semilunar. It
is in relation with, and strengthened by, the extensor tendons which pass over it.
The internal lateral ligament (fig. 232) is fan-shaped, with its apex above, at
the styloid process of the ulna, to which it is attached on all sides, blending with
the apex of the fibro-cartilage. Some of the fibres pass forwards and outwards to
the base of the pisiform bone and to the inner part of the upper border of the
anterior annular ligament, where it is attached to the pisiform bone; they form
a thick, rounded fasciculus on the front of the wrist. Other fibres descend vertically
to the inner side of the cuneiform bone, and others again outwards to the dorsal
surface of the cuneiform. The tendon of the extensor carpi ulnaris is posterior
to, and passes over, part of the fibres of the ligament.
FIG. 232.-POSTERIOR VIEW OF WRIST.

Posterior radio-carpal
ligament
Capsule of carpo-meta-
carpal joint of thumb
Posterior radio-
ulnar ligament
Internal lateral
ligament of wrist
The external lateral ligament (fig. 231) consists of fibres which radiate from
the fore part and tip of the styloid process of the radius. Some pass downwards
and inwards, in front, to the scaphoid and adjacent edge of the magnum; others
downwards, a little forwards and inwards, to the tubercle of the scaphoid and ridge
of the trapezium; and others downwards and outwards to the rough dorsal surface
of the scaphoid. The fibres of this ligament are not so long and strong, nor do
they radiate so much as those of the internal lateral ligament. It is in relation
with the radial artery, and the extensor ossis metacarpi and primi internodii
pollicis, the artery separating the tendons from the ligament.
The synovial membrane is extensive, but does not usually communicate with
the synovial membrane of the inferior radio-ulnar joint, being shut out by the
triangular cartilage. It is also shut out, in almost every instance, from that of the
carpal joints by the interosseous ligaments between the first row of carpal bones.
The styloid process of the radius is cartilage-covered internally, and forms part
of the articular cavity, while that of the ulna does not.


248
THE ARTICULATIONS
The arterial supply is derived from the anterior and posterior carpal arches, the
posterior division of the anterior interosseous, from twigs direct from the radial and
ulnar arteries, and from recurrent branches from the first dorsal interosseous.
The nerve-supply is derived from the ulnar and median in front, and the posterior
interosseous behind.
Movements.-The wrist is a double hinge joint, allowing movements round a
transverse axis, i.e. flexion and extension; and around an antero-posterior axis, i.e.
abduction and adduction; together with a combination of these in quick succession
-circumduction. Lacking only rotation on a vertical axis, it thus possesses
most of the movements of a ball-and-socket joint, without the weakness and
FIG. 233.--FRONT OF WRIST WITH ANTERIOR ANNULAR LIGAMENT.
Anterior radio-ulnar
ligament
Internal lateral ligament of
wrist with slip to annular
ligament
PISIFORM
Anterior annular ligament
Anterior radio-carpal
ligament
Tendon of the flexor
carpi radialis
liability to dislocation which are peculiar to these joints. This deficiency of rotation
is compensated for by the movements of the radius at the radio-ulnar joints,
viz. supination and pronation. Its strength depends chiefly upon the number of
tendons which pass over it, and the close connection which exists between the
fibrous tissue of their sheaths and the capsule of the wrist; also upon the proximity
of the medio-carpal and carpo-metacarpal joints, which permits shocks and jars to
be shared and distributed between them; another source of strength is the absence
of any long bone on the distal side of the joint. In flexion and extension the
carpus rolls forwards and backwards beneath the arch formed by the radius and
fibro-cartilage; flexion being limited by the posterior ligament and posterior
portions of the lateral; extension by the anterior, and anterior portions of the
lateral ligaments. In adduction and abduction, the carpal bones glide from
THE RADIO-CARPAL
249
without inwards and from within outwards. Abduction being more limited than
adduction, and being checked by the internal lateral ligament and by contact of
the styloid process of the radius with the trapezium; adduction being checked by
the external lateral ligament alone. One reason for adduction being more free
than abduction is that the ulna does not reach so low down as the radius, and
the yielding fibro-cartilage allows of greater movement upwards of the inner end of
the carpus. In circumduction the hand moves so as to describe a cone, the apex
of which is at the wrist. These movements are made more easy and extensive by
the slight gliding of the carpal bones upon one another, and the comparatively
free motion at the medio-carpal joint. The oblique direction of the fibres of the
lateral ligaments prevents any rotation at the radio-carpal joint, while it permits
considerable freedom of abduction and adduction.
7. THE CARPAL JOINTS
The joints of the carpus may be subdivided into-
(a) The joints of the first row.
(b) The joints of the second row.
(c) The medio-carpal, or junction of the two rows with each other.
(a) THE UNION OF THE FIRST ROW OF CARPAL BONES
Class.-Diarthrosis.
Subdivision.--Arthrodia.
The bones of the first row, the pisiform excepted, are united by two sets of
ligaments and two interosseous fibro-cartilages.
Dorsal.
Interosseous fibro-cartilages.
Palmar.
Their
The two dorsal ligaments extend transversely between the bones, and connect
the scaphoid with the semilunar, and the semilunar with the cuneiform.
posterior surfaces are in contact with the posterior ligament of the wrist.
The two palmar ligaments extend nearly transversely between the bones
connecting the scaphoid with the semilunar, and the semilunar with the cuneiform.
They are stronger than the dorsal ligaments, and are placed beneath the anterior
ligament of the wrist.
The two interosseous fibro-cartilages (fig. 235) are interposed between the
scaphoid and semilunar, and the semilunar and cuneiform bones, reaching from
the dorsal to the palmar surfaces, and being connected with the dorsal and
palmar ligaments. They are narrow fibro-cartilages which extend between small
portions only of the osseous surfaces. They help to form the convex carpal surface
of the radio-carpal joint, and are somewhat wedge-shaped, their bases being towards
the wrist, and their thin edges between the adjacent articular surfaces of the bones.
The synovial membrane is a prolongation from that of the medio-carpal joint.
The arterial and nerve supplies are the same as for the medio-carpal joint.

THE UNION OF THE PISIFORM BONE WITH THE REST OF THE FIRST Row
This is an arthrodial joint which has a loose fibrous capsule attached to both
the pisiform and cuneiform bones just beyond the margins of their articular surfaces.
It is lined by a separate synovial membrane. Two strong rounded or flattened
bands pass downwards from the pisiform, one to the process of the unciform, and
the other to the base of the fifth metacarpal bone; these may be regarded as

250
THE ARTICULATIONS
prolongations of the tendon of the flexor carpi ulnaris, and the pisiform bone may
be looked upon in the light of a sesamoid bone developed in that tendon.
(b) THE UNION OF THE SECOND ROW OF CARPAL BONES
Class.-Diarthrosis.
Subdivision. Arthrodia.
--
The four bones of this row are united to one another by three dorsal, three
palmar, and two interosseous ligaments.
The three dorsal ligaments (fig. 234) extend transversely and connect the
trapezium with the trapezoid, the trapezoid with the magnum, and the magnum
with the unciform.
The three palmar ligaments are stronger than the dorsal, and are deeply placed
beneath the mass of extensor tendons; they extend transversely between the bones
in a similar manner to the dorsal ligaments.
The two interosseous ligaments are situated on either side of the magnum,
which they connect with the trapezoid on the outer, and the unciform on the
inner, side. That between the magnum and trapezoid is attached to the apposed
surfaces near their dorsal, i.e. the posterior aspect. That between the magnum
and unciform (fig. 235) is attached to the apposed surfaces at their lower and
anterior, i.e. the palmar aspect.
The synovial membrane is a prolongation of that lining the medio-carpal joint.
The arterial and nerve supplies are the same as for the medio-carpal joint.
(c) THE MEDIO-CARPAL JOINT, OR THE UNION OF THE TWO Rows OF THE
CARPUS WITH ONE ANOTHER
The inferior surfaces of the bones of the first row are adapted to the superior
articular surfaces of the bones of the second row. The line of this articulation is
concavo-convex from side to side, and is sometimes described as having the course
of a Roman S placed horizontally, a resemblance by no means strained. (i)
The outer part of the first row consists of the scaphoid alone; it is convex, and bears
the trapezium and trapezoid. (ii) Then follows a transversely elongated socket
formed by the inner part of the scaphoid, the semilunar and cuneiform, into which
are received (a) the head of the magnum, which articulates with the scaphoid
and semilunar; (b) the upper and outer angle of the unciform, which articulates
with the semilunar; and (c) the upper convex portion of the internal surface of
the unciform, which articulates with the external and concave portion of the inferior
surface of the cuneiform. (iii) The innermost part of the inferior surface of the
cuneiform bone is convex, and turned a little backwards to fit into the lower portion
of the internal surface of the unciform, which is a little concave and turned for-
wards to receive it. The central part, which forms a socket for the magnum and
unciform, has somewhat the character of a compound complex ball-and-socket
joint; the other portions are typically arthrodial. The ligaments are: (1) anterior
medio-carpal; (2) posterior medio-carpal; (3) transverse dorsal.
The anterior or palmar medio-carpal is a ligament of considerable strength,
consisting mostly of fibres which radiate from the magnum to the scaphoid, semi-
lunar, and cuneiform; some few fibres connect the trapezoid and trapezium with
the scaphoid, and others pass between the unciform and cuneiform. It is covered
over and thickened by fibrous tissue derived from the sheaths of the flexor tendons
and the fibres of origin of the small muscles of the thumb and little finger.
The posterior or dorsal medio-carpal ligament consists of fibres passing
obliquely from the bones of the first row to those of the second. It is stronger on
the ulnar side than on the radial, but is not so strong as the palmar ligament.
The transverse dorsal ligament (fig. 234) is an additional band, well marked
THE CARPAL JOINTS
251
and often of considerable strength, which passes across the head of the magnum
from the back of the scaphoid to the back of the cuneiform bone; besides binding
down the head of the magnum, it serves to fix the upper and outer angle of the
unciform in the socket formed by the first row.
The dorsal ligaments, like the palmar, are strengthened by a quantity of fibrous
tissue belonging to the sheaths of the extensor tendons and an extension of some
of the fibres of the capsule of the wrist. There are no proper lateral medio-carpal
ligaments; they are but prolongations of the lateral ligaments of the wrist.
The synovial membrane (fig. 235) of the carpus is common to all the joints of
the carpus, and extends to the bases of the four inner metacarpal bones. Thus,
besides lining the inter- or medio-carpal joint, it sends two processes upwards between
the three bones of the first row, and three downwards between the contiguous
surfaces of the trapezoid and trapezium, the trapezium and magnum, and magnum
and unciform. From the latter, prolongations run between the carpo-metacarpal
FIG. 234.-POSTERIOR VIEW OF WRIST, WITH CAPSULE CUT TO
SHOW ARTICULAR SURFACES.

Transverse dorsal ligament
Lower end of interosseous
ligament
Inferior oblique ligament
Triangular fibro-cartilage
Band of posterior ligament of
wrist left to keep bones in
situ
Tendon flexor carpi ulnaris
joints of the four inner bones, and three processes are sent down between the
contiguous sides of the four inner metacarpal bones.
The arterial supply is derived from (a) the anterior and posterior carpal branches
of the radial and ulnar arteries; (b) the carpal branch of the anterior interosseous,
the recurrent branch; and (c) branches from the deep carpal arch. The terminal
twigs of the anterior and posterior interosseous supply the joint on its dorsal
aspect.
The nerve-supply comes from the ulna on the ulnar side, the median on the
radial side, and the posterior interosseous behind.
The movements of the carpal articulations between bones of the same row are
very limited and consist only of slight gliding upon one another; but, slight as they
are, they give elasticity to the carpus to break the jars and shocks which result
from blows or falls upon the hand.
The movements of one row of bones upon the other at the medio-carpal joint
are more extensive, especially in the direction of flexion and extension, so that the

252
THE ARTICULATIONS
hand enjoys a greater range of these movements than is permitted at the wrist
joint alone. At the wrist, extension is more free than flexion; but this is
balanced by the greater freedom of flexion than of extension at the medio-carpal
joint, and by flexion at the carpo-metacarpal joint, so that on the whole the
range of flexion of the hand is greater than that of extension.
FIG. 235.-SYNOVIAL MEMBRANES OF WRIST, HAND, AND FINGERS.
Synovial sac of the inferior
radio-ulnar joint
Synovial sac of the carpus
Synovial sac, occasionally
separate, for the fourth
and fifth metacarpal
bones
Synovial sac of the wrist joint
Synovial sac of the carpo-
metacarpal joint of the
thumb
Lateral ligaments of the meta-
carpo-phalangeal, and inter-
phalangeal joints
A slight amount of lateral motion accompanied by a limited degree of rotation
also takes place; this rotation consists in the head of the magnum and the
superior and outer angle of the unciform bone rotating in the socket formed by
the three bones of the upper row, and in a gliding forwards and backwards of
the trapezium and trapezoid upon the scaphoid.d
In addition to the ligaments, the undulating outline and the variety of shapes
of the apposed facets render this joint very secure.
THE CARPO-METACARPAL JOINTS
253
Bearing in mind the mobility of this medio-carpal joint and of the carpo-
metacarpal, we see at once the reason for the radial and ulnar flexors and extensors
being prolonged down to their insertion into the base of the metacarpus, for they
produce the combined effect of motion at each of the three transverse articulations:
(1) at the wrist; (2) at the medio-carpal; (3) at the carpo-metacarpal joints.
8. THE CARPO-METACARPAL JOINTS
These may be divided into two sets, namely:-
(a) The carpo-metacarpal joints of the four inner fingers.
(b) The carpo-metacarpal joint of the thumb.
The inferior surfaces of three of the bones of the second row of the carpus
present a combined surface for the four inner metacarpal bones; the trapezium
presents a distinct and separate saddle-shaped surface for the base of the meta-
carpal bone of the thumb.
(a) THE FOUR INNER CARPO-METACARPAL JOINTS
Class.-Diarthrosis.
Subdivision.-Arthrodia.
These joints exist between the trapezium, trapezoid, magnum, and unciform
bones above, and the four inner metacarpal bones below. The ligaments which
unite them are, dorsal, palmar, and interosseous.
The dorsal ligaments (fig. 234).-Three dorsal ligaments pass to the second
metacarpal bone: one from each of the carpal bones with which it articulates,
viz. the trapezium, trapezoid, and magnum. Two dorsal bands pass from the
magnum to the third metacarpal bone. Two dorsal bands pass to the fourth
bone: one from the unciform, and another from the magnum; the latter is
sometimes wanting. The fifth bone has only one band passing to it from the
unciform.
The palmar ligaments.-One strong band passes from the second metacarpal
bone to the trapezium internal to the ridge for the annular ligament; it is covered
by the sheath of the flexor carpi radialis.
Three bands pass from the third metacarpal: one outwards to the trapezium, a
middle one upwards to the magnum, and a third inwards over the fourth to reach
the fifth metacarpal and the unciform bones.
One ligament connects the fourth bone to the unciform.
One ligament connects the fifth bone to the unciform, the fibres extending
internally, and connecting the dorsal and palmar ligaments. The ligament to the
fifth bone is strengthened in front by the prolonged fibres of the flexor carpi ulnaris
and the strong inner slip of the ligament of the third metacarpal bone; and
posteriorly, by the tendon of the extensor carpi ulnaris.
The interosseous ligament (fig. 235) is limited to one part of the articulation,
and consists of short strong fibres connecting the contiguous angles of the unciform
and magnum, and the third and fourth metacarpal bones towards their palmar
aspect. There is, however, a thick strong ligament connecting the edge of the
trapezium with the outer border of the base of the second metacarpal bone; it helps
to separate the carpo-metacarpal joint of the thumb from the common carpo-
metacarpal joint, and to close in the radial side of the latter joint.
The synovial membrane is a continuation of the medio-carpal joint; occa-
sionally there is a separate membrane between the unciform and fourth and fifth
metacarpal bones (fig. 235); while that between the fourth and magnum is lined
by the synovial sac of the common joint.


254
THE ARTICULATIONS
The arteries to the four inner carpo-metacarpal joints are as follow:-
(1) For the index finger: twigs, are supplied by the trunk of the radial on the
dorsal and palmar aspects, the metacarpal, the dorsalis indicis, and the radialis
indicis.
(2) For the middle finger: the metacarpal, first dorsal interosseous by the
branch which passes upwards to join the posterior carpal arch, and a branch from
the deep palmar arch which joins the anterior carpal arch.
(3) For the ring finger: the deep palmar arch and recurrent twigs from the
second dorsal interosseous in the same manner as for the middle finger.
(4) For the little finger: the ulnar and its deep branch; also twigs from the
second dorsal interosseous.
The nerves are supplied to these joints by the deep palmar branch of the ulnar,
the posterior interosseous, and the median.
The movements permitted at these joints, though slight, serve to increase those
of the medio-carpal and wrist joints. The joint between the fifth metacarpal and
the unciform bones approaches somewhat in shape and mobility the first carpo-
metacarpal joint; it has a greater range of flexion and extension, but its lateral
movement is nearly as limited as that of the three other metacarpal bones; the
process of the unciform bone limits its flexion. Lateral motion towards the ulnar
side is checked by the strong palmar band which unites the base of the fifth
metacarpal to the base of the third, and the strong transverse ligament at the head
of the bones. The mobility of the second, third, and fourth metacarpal bones
is very limited, and consists almost entirely of a slight gliding upon the carpal
bones, i.e. flexion and extension; that of the third and fourth bones is extremely
slight, as there is no long flexor attached to either; but, owing to the close con-
nection of the bases of the metacarpal bones, the flexor and extensor radial and
ulnar muscles act on all by their pull on the particular bone into which they are
inserted.
Abduction, or movement toward the radial side, is prevented by the impaction
of the second bone against the trapezium; a little adduction is permitted, and is
favoured by the slope given to the unciform and fifth metacarpal bones.
There is also a slight gliding between the fourth and fifth bones, when the
concavity they present towards the palm is deepened to form the '
cup of Diogenes.'
Class.
(b) THE CARPO-METACARPAL JOINT OF THE THUMB
Diarthrosis.
Subdivision. Arthrodia.
The bones entering into this joint are the base of the first metacarpal, and the
trapezium. The first metacarpal bone diverges from the other four, contrasting
very strongly with the position of the great toe. It is due to this divergence that
the thumb is able to be opposed to each and all the fingers. The ligament which
unites the bones is the
Capsular.
The capsular ligament (figs. 231 and 232) consists of fibres which pass from
the margin of the articular facet on the trapezium, to the margin of the articular
facet at the base of the first metacarpal bone. The fibres are stronger on the dorsal
than on the palmar aspect. They are not tense enough to hold the bones in close
contact, so that while they restrict they do not prevent motion in any direction.
The internal fibres are stronger than the external.
The synovial membrane is lax, and distinct from the other synovial membranes
of the carpus.
The arteries of the carpo-metacarpal joint of the thumb are derived from the
trunk of the radial, the arteria princeps pollicis, and the dorsales pollicis.
THE CARPO-METACARPAL JOINTS
255
The nerves are supplied by the branches of the median to the thumb.
The movements of this joint are regulated by the shape of the articular surfaces,
rather than by the ligaments, and consist of flexion, extension, abduction, adduc-
tion, and circumduction. In flexion and extension the metacarpal bone slides to
and fro upon the trapezium; in abduction and adduction it slides from side to side
or, more correctly, revolves upon the antero-posterior axis of the joint. The power
of opposing the thumb to any of the fingers is due to the forward and inward
obliquity of its flexion movement, which is by far its most extensive motion.
Abduction is very free, while adduction is limited on account of the proximity of
the second metacarpal bone. The movement of the trapezium upon the rest of the
carpus somewhat increases the range of all the movements of the thumb.
9. THE INTERCARPAL ARTICULATIONS
Class.-Diarthrosis.
Subdivision.-Arthrodia.
The metacarpal of the thumb is not connected with any other metacarpal bone.
Those of the second, third, fourth, and fifth are in actual contact at their bases,
and are held firmly together by the following ligaments:-
Dorsal.
Palmar.
Interosseous ligaments.
The dorsal ligaments (fig. 233) are layers of variable thickness of strong, short
fibres, which pass transversely from bone to bone, filling up the irregularities on
the dorsal surfaces.
The palmar ligaments are transverse layers of ligamentous tissue passing from
bone to bone; they cannot be well defined from the other ligaments and fibrous
tissue covering the bones.
The interosseous ligaments (fig. 235) pass between the apposed surfaces of the
bones, and are attached to the distal sides of the articular facets, so as to close in
the synovial cavities on this aspect; where there are two articular facets, the
fibres extend upwards between them, nearly as far as their carpal facets. That
between the fourth and fifth is the weakest.
The arteries to the intermetacarpal joints are twigs from the palmar and dorsal
interosseous arteries; the twigs pass upwards between the interosseous muscles.
The nerves are derived from the ulnar and the posterior interosseous.
The synovial membrane is prolonged downwards from the common carpal sac.

THE UNION OF THE HEADS OF THE METACARPAL BONES
The distal extremities of these bones are connected together on their palmar
aspects by what is called the transverse ligament. This consists of three short
bands of fibrous tissue, which unite the second and third, third and fourth, and the
fourth and fifth bones. They are rather more than a quarter of an inch (6 mm.)
deep, and rather less in width, and limit the distance to which the metacarpal bones
can be separated. They are continuous above with the fascia covering the inter-
osseous muscles; below, they are connected with the subcutaneous tissue of the
web of the band. They are on a level with the front surfaces of the bones, and are
blended at either side with the edges of the glenoid ligament in front, with the
lateral ligaments of the metacarpo-phalangeal joint, and also with the sheaths of
the tendons. In front, a lumbrical muscle passes with the digital arteries and
nerves; while behind, the interossei pass to their insertions.

256
THE ARTICULATIONS
10. THE METACARPO-PHALANGEAL JOINTS
(a) THE METACARPO-PHALANGEAL JOINTS OF THE FOUR INNER FINGERS
Subdivision.-Ginglymus.
Class.-Diarthrosis.
In these joints the cup-shaped extremity of the base of the first phalanx fits
on to the rounded head of the metacarpal bone, and is united by the following
ligaments:-
Lateral.
Glenoid.
The glenoid ligament (fig. 236) is a fibro-cartilaginous plate which seems more
intended to increase the depth of the phalangeal articular facet in front, than to
FIG. 236.-ANTERIOR AND POSTERIOR VIEW OF LIGAMENTS OF THE FINGERS.
Transverse ligament
between the heads
of the metacarpal
bones
Glenoid ligament
Lateral ligament
Areolar tissue
capsule
Lateral ligament
Glenoid ligament
Lateral ligament
Flexor tendon
Areolar tissue
capsule
Lateral ligament
Extensor tendon
Flexor tendon
Slips of the extensor
tendon
unite the two bones. It is much more firmly attached to the margin of the phalanx
than to the metacarpal bone, being only loosely connected with the palmar surface
of the latter by some loose areolar tissue which covers in the synovial sac, here
prolonged upon the surface of the bone some little distance. Laterally, it is
connected with the lateral ligaments and the transverse metacarpal ligament. It
corresponds to the sesamoid bones of the thumb; a sesamoid bone sometimes
exists at the inner border of the joint of the little finger.
The lateral ligaments (figs. 235, 236) are strong and firmly connect the bones
with one another; each is attached above to the lateral tubercle, and to a depression
in front of the tubercle, of the metacarpal bone. From this point the fibres spread
widely as they descend on the side of the base of the phalanx; the anterior fibres
THE METACARPO-PHALANGEAL JOINTS
257
are connected with the glenoid ligament; the posterior blend with the tendinous
expansion at the back of the joint.
The joint is covered in posteriorly by the expansion of the extensor tendon, and
some loose areolar tissue passing from its under surface to the bones (fig. 236).
The synovial sac is loose and capacious, more especially over the base of the
phalanx behind, and the head of the metacarpal bone in front.
The arteries come from the digital or anterior interosseous vessels of the deep
arch.
The nerves are derived from the digital branches, or from twigs of the nerves to
the interosseous muscles.
The movements permitted at these joints are: flexion, extension, abduction,
adduction, and circumduction. Flexion is the most free of all, and may be continued
until the phalanx is at a right angle with the metacarpal bone. It is on this
account that the articular surface of the head of the bone is prolonged so much
further on the palmar aspect, and that the synovial sac is here so loose and ample.
Extension is the most limited of the movements, and can only be carried to a little
beyond the straight line. Abduction and adduction are fairly free, but not so free
as flexion; as a rule, though these movements can be executed separately, flexion
is associated with adduction, and extension with abduction. This may be proved by
opening the hand, when the fingers involuntarily separate as they extend, while in
closing the fist they come together again. The free abduction, adduction, and
circumduction which is permitted at these joints is due to the fact that the long
axes of the articular facets are at right angles to one another.
(b) THE METACARPO-PHALANGEAL JOINT OF THE THUMB
Class.-Diarthrosis.
Subdivision. Ginglymus.
The head of the metacarpal bone of the thumb differs considerably from the
corresponding ends of the metacarpal bones of the fingers. It is less convex,
wider from side to side, the palmar edge of the articular surface is raised and
irregular, and here on either side of the median line are the two facets for the
sesamoid bones. The base of the first phalanx of the thumb, too, is more like the
base of the second phalanx of one of the other fingers. The ligaments are:-
Lateral.
Posterior.

Sesamoid bones in place of a glenoid ligament.
The lateral ligaments are short, strong bands of fibres, which radiate from
depressions on either side of the head of the metacarpal bone to the base of the
first phalanx and sesamoid bones. As they descend they pass a little forwards,
so that the greater number are inserted in front of the centre of motion.
The posterior ligament consists of scattered fibres which pass across the joint
from one lateral ligament to the other, completing the capsule and protecting the
synovial sac.
The sesamoid bones are two in number, situated on either side of the middle
line, and connected together by strong transverse fibres which form the floor of the
groove for the long flexor tendon; they are connected with the base of the phalanx
and head of the metacarpal bone by strong fibres. Anteriorly they give attach-
ment to the short muscles of the thumb, and posteriorly are smooth for the purpose
of gliding over the facets. The lateral ligaments are partly inserted into their sides.
The arteries and nerves come from the digital branches of the thumb.
The movements are chiefly flexion and extension, very little lateral movement
being permitted, and that only when the joint is slightly bent. Thus this joint is
more ginglymoid than the corresponding articulations of the fingers. The thumb
S

258
THE ARTICULATIONS
gets its freedom of motion at the carpo-metacarpal joint; the fingers get theirs
at the metacarpo-phalangeal, but they have not so much freedom as the thumb
enjoys.
11. THE INTERPHALANGEAL ARTICULATIONS
Class.-Diarthrosis.
Subdivision.-Ginglymus.
The ligaments which unite the phalanges of the thumb and of the fingers are:-
Glenoid.
Lateral.
The glenoid ligament (fig. 236), sometimes called the sesamoid body, is very
firmly connected with the base of the distal bone, and loosely, by means of fibro-
areolar tissue, with the head of the proximal one. It blends with the lateral
ligaments at the sides, and over it pass the flexor tendons. Occasionally a sesamoid
bone is developed in the cartilage of the interphalangeal joint of the thumb.
The lateral ligaments (figs. 235 and 236) are strong bands which are attached
to the rough depressions on the sides of the upper phalanx, and to the projecting
lateral margins of the lower phalanx of each joint. They are tense in every
position, and entirely prevent any lateral motion; they are connected posteriorly
with the expansion of the extensor tendon.
Posteriorly (fig. 236) the joint is covered in by the deep surface of the extensor
tendon, and a little fibro-areolar tissue extends from the tendon, and thickens the
posterior portion of the synovial sac, and completes the capsule.
The synovial membrane is loose and ample, and extends upwards a little way
along the shaft of the proximal bone.
The arteries and nerves come from their respective digital branches.
The movements are limited to flexion and extension. Flexion is more free, and
can be continued till one bone is at right angles with the other, and is most free
at the junction of the first and second bones; the second phalanx can be flexed on
the first through 110° to 115° when the latter is not flexed. The greater freedom of
flexion is due to the greater extent of the articular surface in front of the heads of
the proximal bones, and to the direction of the fibres of the lateral ligaments, which
pass a little forwards to their insertion into the distal bone.
THE ARTICULATIONS OF THE LOWER LIMB
The articulations of the lower limb are the following:--
1. The hip joint.
2. The knee joint.
3. The tibio-fibular union.
4. The ankle joint.
5. The tarsal joints.
6. The tarso-metatarsal joints.
7. The intermetatarsal joints.
8. The metatarso-phalangeal joints.
9. The interphalangeal joints.
THE HIP JOINT
259
1. THE HIP JOINT
Subdivision.
Enarthrodia.
Class.-Diarthrosis.
The hip is the most typical example of a ball-and-socket joint in the body, the
round head of the femur being received into the cup-shaped cavity of the aceta-
bulum. Both articular surfaces are coated with cartilage, that covering the head
of the femur being thicker above where it has to bear the weight of the body,
and thinning out to a mere edge below; the pit for the ligamentum teres is the
only part uncoated, but the cartilage is somewhat heaped up round its margins.
Covering the acetabulum, the cartilage is horseshoe-shaped, and thicker above than
below, being deficient over the depression at the bottom of the acetabulum, where
a mass of fatty tissue-the so-called synovial or Haversian gland-is lodged.
The ligaments of the joint are:-
Capsular.
Transverse.
Ligamentum teres.
Cotyloid cartilage.
The capsular ligament is one of the strongest ligaments in the body. It is
large and somewhat loose, so that in every position of the body some portion of it
is relaxed. At the pelvis it is attached, superiorly, to the base of the anterior
superior iliac spine; curving backwards, it becomes blended with the deep surface
of the reflected tendon of the rectus femoris; posteriorly, it is attached a few lines
from the acetabular rim; and below, to the upper edge of the groove between the
acetabulum and tuberosity of the ischium. Thus it reaches the transverse liga-
ment, being firmly blended with its outer surface, and frequently sends fibres
beyond the notch to blend with the obturator membrane. Anteriorly it is attached
to the pubes near the notch, to the pectineal eminence, and thence backwards to
the base of the iliac spine. A thin strong stratum is given off from its superficial
aspect posteriorly, which extends beneath the gluteus minimus, and small rotators,
to be attached above to the dorsum of the ilium higher than the reflected tendon
of the rectus, and behind to the ilium and ischium nearly as far as the sciatic
notch. As this expansion passes over the long tendon of the rectus, the tendon
may be described as being in part contained within the substance of the capsule.
At the femur, the capsular ligament is fixed to the anterior portion of the upper
border of the great trochanter, and to the superior cervical tubercle. Thence it
runs down the spiral line as far as the inner border of the femur, where it is on a
level with the lower part of the lesser trochanter. It then runs upwards and back-
wards along an oblique line about two-thirds of an inch (1.6 cm.) in front of the
lesser trochanter, and continues upwards along the back of the neck nearly
parallel to the posterior intertrochanteric line, and from one-half to two-thirds of
an inch (12 to 16 mm.) above it; finally, it passes along the inner side of the
digital fossa to reach the anterior superior angle of the great trochanter.
On laying open the capsule, some of the deeper fibres are seen reflected
upwards along the neck of the femur, to be attached much nearer the head:
these are the retinacula. One corresponds to the upper, and another to the lower
part of the spiral line; a third is seen at the upper and back part of the neck.
They form flat bands, which lie on the femoral neck.
Superadded to the capsule, and considerably strengthening it, are three auxi-
liary bands, whose fibres are intimately blended with, and in fact form part of,
the capsule, viz. the ilio-femoral, ischio-femoral, and pectineo-femoral bands.
The ilio-femoral (fig. 237) is the longest, widest, and strongest of the bands.
It is of triangular shape, with the apex attached above to a curved line on the ilium
immediately below and behind the anterior inferior spine, and its base below to the

s 2

260
THE ARTICULATIONS
anterior edge of the greater trochanter and to the spiral line as far as the inner border
of the shaft. The highest or outermost fibres are coarse, almost straight, and shorter
than the rest; the innermost fibres are also thick and strong, but oblique. This
varying obliquity of the fibres, and their accumulation at the borders, explains why
this band has been described as the Y-shaped ligament. About the centre of its base,
near the femoral attachment, is an aperture transmitting an articular twig from
the transverse branch of the external circumflex artery.
The ischio-femoral band (fig. 238) is formed of very strong fibres attached all
along the upper border of the groove for the external obturator, and to the ischial
margin of the acetabulum above the groove. The highest of these incline a little
FIG. 237.-ANTERIOR VIEW OF THE CAPSULE OF THE HIP JOINT.
Tendon of rectus pulled up
Tendino-trochanteric band passing
between rectus and vastus externus
Placed on the weak spot of capsule,
which is sometimes perforated to
allow the bursa under psoas to com-
municate with joint
Ilio-femoral band
- Pectineo-femoral band
upwards as they pass outwards to be fixed to the greater trochanter in front of the
insertion of the pyriformis tendon, while the other fibres curve more and more
upwards as they pass outwards to their insertion at the inner side of the digital
fossa, blending with the insertion of the external rotator tendons. When the joint
is in flexion these fibres pass in nearly straight lines to their femoral attachment,
and spread out uniformly over the head of the femur; but in extension they wind
over the back of the femur in a zonular manner, embracing the posterior aspect of
the neck of the femur.
The pectineo-femoral band (fig. 237) is a distinct but narrow set of fibres which
are individually less marked than the fibres of the other two bands; they are fixed
above to the anterior border of the pectineal eminence, reaching as far down as the
pubic end of the cotyloid notch. Below, they reach the neck of the femur, and are
fixed above and behind the lowermost fibres of the ilio-femoral band, with which
they blend.
THE HIP JOINT
261
In thickness and strength the capsule varies greatly; thus, if two lines be
drawn, one from the anterior inferior spine to the inner border of the femur near
the lesser trochanter, and the other from the anterior part of the groove for the
external obturator to the digital fossa, all the ligament between those lines on the
outer and upper aspects of the joint is very thick and strong, and that below and
to the inner side, except at the narrow pectineo-femoral band, is thin and weak, so
that the head of the bone can be seen through it. The capsule is thickest in the
course of the ilio-femoral band, towards the outer part of which it measures over a
quarter of an inch (6 mm.). Between the ilio-femoral and ischio-femoral bands
the capsule is very strong, and with it here near the acetabulum is incorporated
the reflected tendon of the rectus, and here also a triangular band of fibres runs
FIG. 238.-POSTERIOR VIEW OF THE CAPSULE OF THE HIP JOINT.

Here are seen the re-
flected tendon of the
rectus and the tri-
angular ilio-trochan-
teric' band
Ischio-femoral band
This is placed on the weak
portion of the capsule
downwards and forwards to be attached by a narrow insertion to the ridge on
the front border of the greater trochanter near the gluteus minimus (the ilio-
trochanteric band) (fig. 238).
The capsule is strengthened here also by a strong band from the under surface
of the gluteus minimus, and by the tendino-trochanteric band which passes down
from the reflected tendon of the rectus to the vastus externus (fig. 237). This
is closely blended with the capsule near the outer edge of the ilio-femoral ligament.
The thinnest part of the capsule is between the pectineo-femoral and ilio-
femoral bands; this is sometimes perforated, allowing the bursa under the psoas
to communicate with the joint. The capsule is also very thin at its attachment to
the back of the femoral neck, and again opposite the cotyloid notch.
The ligamentum teres (figs. 239 and 240) is an interarticular flat band which
extends from the acetabular notch to the head of the femur, and is usually about

262
THE ARTICULATIONS
an inch and a half (3.7 cm.) long. It has two bony attachments, one on either side
of the cotyloid notch immediately below the articular cartilage, while intermediate
fibres spring from the under surface of the transverse ligament. The ischial
portion is the stronger, and has several of its fibres arising outside the cavity,
below and in connection with the origin of the transverse ligament, where it is
also continuous with the capsule, and periosteum of the ischium. At the femur it
is fixed to the front part of the depression on the head, and also to the cartilage
round the margins of the depression. It is covered by a prolongation of synovial
membrane, which also covers the cushion of fat in the recess of the acetabulum;
the portion reflected over the fatty tissue does not cling closely to the round
ligament, but forms a triangular fold, the apex of which is at the femur.
The transverse ligament (fig. 241) passes across the cotyloid notch and
converts it into a foramen; it supports part of the cotyloid fibro-cartilage, and is
FIG. 239.-SECTION THROUGH THE HIP JOINT, SHOWING THE COTYLOID LIGAMENT,
LIGAMENTUM TERES, AND RETINACULA.
Ligamentum teres.
The upper line is
placed on the
femoral, the lower
on the ischial at-
tachment
Cotyloid
cartilage
Capsular
ligament
Reflected fibres
of capsule (re-
tinacula)
Reflected fibres
of capsule
connected with the ligamentum teres and the capsule. It is composed of decussa-
ting fibres, which arise from the margin of the acetabulum on either side of the
notch, those coming from the pubes being more superficial, and passing to form
the deep part of the ligament at the ischium, while those superficial at the ischium
are deep at the pubes. It thus completes the rim of the acetabulum.
The cotyloid fibro-cartilage (figs. 239, 240) is a yellowish-white structure,
which deepens the acetabulum by surmounting its margin. It varies in strength
and thickness, but is stronger at its iliac and ischial portions than elsewhere. Its
base is broad and fixed to the bony rim as well as to the articular cartilage of
the acetabulum on the inner, and the periosteum on the outer side of it, and blends
inseparably with the transverse ligament which supports it over the cotyloid
notch. Its free margin is thin; on section it is somewhat lunated, having its
outer surface convex and its articular face concave and very smooth in adaptation
THE HIP JOINT
263
to the head of the bone, which it tightly embraces a little beyond its greatest
circumference. It somewhat contracts the aperture of the acetabulum, and retains
the head of the femur within its grasp after division of the muscles and capsular
ligament. It is covered on both aspects by synovial membrane.
The synovial membrane lines the capsule and both surfaces of the cotyloid
ligament, and passes over the border of the acetabulum to reach and cover the
FIG. 240.-HIP-JOINT AFTER DIVIDING THE CAPSULAR LIGAMENT AND
DISARTICULATING THE FEMUR.

Ligamentum teres.
Capsular ligament.
Capsular ligament, cut
Cotyloid ligament
Capsular ligament
FIG. 241.--PORTIONS OF ISCHIUM AND PUBES, SHOWING THE COTYLOID NOTCH
AND THE LIGAMENTUM TERES ATTACHED OUTSIDE THE ACETABULUM.

Transverse ligament-
-Cotyloid ligament
-Transverse ligament
-Ligamentum teres
attached to ischium
outside the aceta-
bulum
fatty cushion filling its recess. The part covering the fatty cushion is unusually
thick, and is attached round the edges of the rough bony surface on which the
cushion rests. The membrane is loosely reflected off this on to the ligamentum
teres, along which it is prolonged to the head of the femur; thus the fibres of the
round ligament are shut out from the joint cavity. From the capsule the synovial
membrane is also reflected below on to the neck of the femur, passing over the
retinacula to the margin of the articular cartilage.

264
THE ARTICULATIONS
The arterial supply comes from (a) the transverse branches of the internal
and external circumflex arteries; (b) the external branch of the obturator sends a
branch through the cotyloid notch beneath the transverse ligament, which ramifies
in the fat at the bottom of the acetabulum, and travels down the round ligament
to the head of the femur; (c) the inferior branch of the deep division of the gluteal;
and (d) the sciatic arteries.
The nerve-supply comes from (a) anterior crural, (b) anterior division of the
obturator, (c) the accessory obturator, and (d) the sacral plexus, either by a twig from
the nerve to the quadratus femoris, or from the upper part of the great sciatic or
the lower part of the sacral plexus.
The muscles in relation with the hip-joint are: in front, the psoas, which is
separated from the capsule by a bursa, and the iliacus, which in part arises from
the capsule; above are the straight and reflected tendons of the rectus, the re-
flected tendon being enclosed between the layers of the capsule, and a band which
passes down from the reflected tendon to the vastus externus; also the gluteus
minimus, which is closely adherent to the capsule; above and behind are the
pyriformis, which sometimes sends a slip into the capsule; the internal obturator,
which acts as a powerful strap to the back of the joint, and the two gemelli; below
and behind is the external obturator, passing over the capsule, a dense band of
fibro-cellular tissue connects the sheath of the obturator externus with the capsule
along the posterior edge of the muscle; internally is the pectineus.
The movements.-The hip joint, like the shoulder, is a ball-and-socket joint,
but with a much more complete socket and a corresponding limitation of move-
ment. Each variety of movement is permitted, viz. flexion, extension, abduction,
adduction, circumduction, and rotation; and any two or more of these movements
not being antagonistic can be combined, i.e. flexion or extension associated with
abduction or adduction can be combined with rotation in or out.
It results from the obliquity of the neck of the femur that the movements of
the head in the acetabulum are always more or less of a rotatory character. This
is more especially the case during flexion and extension, and two results follow
from it. First, the bearing surfaces of the femur and acetabulum preserve their
apposition to each other, so that the amount of articular surface of the head in the
acetabulum does not sensibly diminish pari passu with the transit of the joint
from the extended to the flexed position, as would be the case necessarily if the
movement of the femoral head, like that of the thigh itself, was simply angular,
instead of rotatory and angular. Secondly, as rotation of the head can continue
until the ligaments are tight without being checked by contact of the neck of the
thigh bone against the rim of the acetabulum, flexion of the thigh as far as the
joint is concerned is practically unlimited. Flexion is the most important, most
frequent, and most extensive movement, and in the dissected limb, before the
ligaments are disturbed, can be carried to 160°, and is then checked by the lower
fibres of the ischio-femoral ligament. In the living subject simple flexion can
continue until checked by the contact of the soft parts at the groin, if the knee be
bent; if the knee be straight, flexion of the hip is checked in most persons by the
hamstring muscles at nearly the right angle. This is very evident on trying to
touch the ground with the fingers without bending the knees, the chief strain
being felt at the popliteal space. This is due to the shortness of the hamstrings.
Extension is limited by the ilio-femoral ligament.
Abduction and outward rotation can be performed freely in every position of
flexion and extension-abduction being limited by the pectineo-femoral ligament;
outward rotation by the ilio-femoral ligament, especially its inner portion, during
extension; but by the outer portion, as well as by the ligamentum teres, during
flexion.
Adduction and inward rotation are very limited in the extended thigh:
THE HIP JOINT
265
adduction on account of the contact with the opposite limb; the inward rotation,
because all the muscles of internal rotation (save the tensor vaginæ femoris) are
also extensors, whereas most of the other extensors are also outward rotators, so
that each set requires to be relaxed by flexion before inward rotation can be perfected.
FIG. 242.-LIGAMENTUM TERES, LAX IN FLEXION.

FIG. 243.-LIGAMENTUM TERES, VERY LAX IN COMPLETE EXTENSION.

In the slightly flexed position adduction is more free, and is then limited by the outer
fibres of the ilio-femoral band and the superior portion of the capsule. In flexion
the range is still greater, and limited by the ischio-femoral ligament, the liga-
mentum teres being also rendered nearly tight. In the nearly extended position,

266
THE ARTICULATIONS
inward rotation is limited by the ilio-femoral ligament; and in flexion by the
ischio-femoral ligament, and the portion of the capsule between it and the ilio-
femoral band.
The ilio-femoral band also prevents the tendency of the trunk to roll backwards
on the thigh bones in the erect posture, and so does away with the necessity
for muscular power for this purpose; it is put on stretch in the stand-at-ease
position.
The ligamentum teres is of but very little use in resisting violence or giving
strength to the joint. It assists in checking rotation outwards and adduction
FIG. 244.-LIGAMENTUM TERES, DRAWN TIGHT IN FLEXION COMBINED WITH
ROTATION OUTWARDS AND ADDUCTION.
during flexion. A ligament can only be of use when it is tight, and it was found
by trephining the bottom of the acetabulum, removing the fat, and threading a
piece of whipcord round the ligament, that the ligament was slack in simple
flexion, and very slack in complete extension, but that its most slack condition was
in abduction. It is tightest in flexion combined with adduction and rotation
outwards, and almost as tight in flexion with outward rotation alone, and in
flexion with adduction alone (figs. 242 to 244).
2. THE KNEE JOINT
Class.-Diarthrosis.
Subdivision.-Ginglymus.
The knee is the largest joint in the body. It is rightly described as a gingly-
moid joint, but there is also an arthrodial element; for, in addition to flexion and
extension, there is a sliding backwards and forwards of the tibia upon the femoral
condyles, as well as slight rotation round a vertical axis. It is one of the most
superficial, and, as far as adaptation of the bony surfaces goes, one of the weakest
joints, for in no position are the bones in more than partial contact. Its strength
lies in the number, size, and arrangement of the ligaments, and the powerful
muscles and fascial expansions which pass over the articulation and enable it to
withstand the leverage of the two longest bones in the body. It may be said to

THE KNEE JOINT
267
consist of two articulations with a common synovial membrane-the patello-
femoral and the tibio-femoral, the latter being double. It is composed of the
condyles and trochlear surface of the femur, the tuberosities of the tibia, and the
patella, united by the following ligaments, which may be divided into an external
and internal set :-
EXTERNAL
(1) Fibrous expansion of the extensors.
(2) Capsular or anterior ligament.
(3) Posterior ligament.
(4) External lateral.
(5) Internal lateral.
(6) Ligamentum patellæ.
INTERNAL
Anterior crucial.
Posterior crucial.
Internal semilunar fibro-cartilage.
External semilunar fibro-cartilage.
Coronary.
Transverse.
The fibrous expansion of the extensor tendons consists (1) of a central portion,
densely thick and strong, an inch and a half (3.7 cm.) broad, which is inserted into
the anterior two-thirds of the upper border of the patella, many of its superficial
fibres passing over the subcutaneous surface of the bone into the ligamentum
patella; (2) of two lateral portions thinner, but strong. The lateral portions are
inserted into the patella along its upper border on either side of the central portion
and also into its lateral borders, nearer the anterior than the posterior surface,
as low down as the attachment of the ligamentum patellæ ; passing thence along
the sides of the ligamentum patella to the tibia, they are attached to the oblique
lines which extend laterally from the tubercle to the inner and outer tuberosities,
and reach as far as the internal and external lateral ligaments. On the outer side
the fibres blend with the ilio-tibial band of the fascia lata, and on the inner they
extend below the oblique line to blend with the periosteum of the shaft. Thus
there is a large hood spread over the whole of the front of the joint, investing the
patella, and reaching from the sides of the ligamentum patella to the lateral
ligaments, attached below to the tibia, and separated everywhere from the synovial
membrane by a layer of fatty tissue.
The ligamentum patella (fig. 247) is simply the continuation of the central
portion of the conjoined tendon, some fibres of which are prolonged over the front
of the patella into the ligament. It is an extremely strong, flat band, attached
above to the lower border of the patella; below, it is fixed to the lower part of the
tubercle and upper part of the crest of the tibia, somewhat obliquely, being pro-
longed downwards further on the outer side, so that this border is fully an inch
longer than the inner which measures two inches and a half (3.7 cm.) in length.
Behind, it is in contact with a mass of fat which separates it from the synovial
membrane, and a small bursa which intervenes between it and the upper part of the
tubercle of the tibia. In front, a large bursa separates it from the subcutaneous
tissue, and laterally it is continuous with the fibrous expansion of the extensors.
The internal lateral ligament (fig. 245) is a strong, flat band, which extends
from the depression on the tubercle on the inner side of the internal condyle of the
femur, to the inner border and internal surface of the shaft of the tibia, an inch
and a half (3.7 cm.) below the tuberosity. It is three inches and a half (8.7 cm.)
long, well defined anteriorly, where it blends with the expansion of the conjoined
extensor tendons; but not so well defined posteriorly, where it merges into the
posterior ligament. Some of the lower fibres blend with the descending portion of
the semimembranosus tendon. Its deep surface is firmly adherent to the edge of
the internal semilunar cartilage and coronary ligament, while part of the semi-
membranosus tendon and inferior internal articular vessels and nerve pass between
it and the bone. Superficially, a bursa separates it from the tendons of the gracilis
and semitendinosus muscles and from the aponeurosis of the sartorius muscle.


268
THE ARTICULATIONS
The external lateral ligament (fig. 245) consists of two portions: the anterior,
which is best marked and longer, is a strong, rounded cord, about two inches
(5 cm.) long, attached above to the tubercle on the outer side of the external
condyle of the femur, just below and in front of the origin of the outer head of the
gastrocnemius, the tendon of the popliteus arising from the groove below and in
front of it. Below, it is fixed to the middle of the outer surface of the head of the
fibula, half an inch (1-25 cm.) or more anterior to the styloid process. Super-
ficially is the tendon of the biceps, which splits to embrace its lower extremity;
while deeper than it passes the popliteus tendon in its sheath, and the inferior
external articular vessels and nerve. Some fibres of the peroneus longus occa-
sionally arise from the lower end of the ligament. The posterior portion is a third
FIG. 245.-POSTERIOR VIEW OF THE KNEE JOINT.
Plantaris-
Tendon of adductor
magnus
Outer head of-
gastrocnemius
Inner head of
gastrocnemius
External lateral ligament:-
anterior portion
Posterior part of external.
lateral ligament
Tendon of popliteus
Tendon of biceps.
Posterior superior
tibio-fibular ligament
-Tendon of semi-mem-
branosus with
its
slip to thicken the
posterior ligament
-Internal lateral
ligament
of an inch (8 mm.) behind the anterior. It is broader and less defined; fixed
below to the styloid process, it inclines upwards and somewhat backwards, and ties
down the popliteus against the outer tuberosity, blending beneath the outer head
of the gastrocnemius with the posterior ligament of which it is really a portion.
The posterior ligament or ligamentum Winslowii (fig. 245) is a broad dense
structure of interlacing fibres, with large orifices for vessels and nerves. It is
attached above to the femur close to the articular margins of the condyles, stretch-
ing across the upper margin of the intercondyloid notch, to which it is connected
by fibro-fatty tissue; it thus reaches across from the internal to the external
lateral ligaments. Below, it is fixed to the border of the outer tuberosity of the
tibia, to the bone just below the popliteal notch, and to the shaft of the tibia
below the inner tuberosity, blending with the descending slip of the semi-

THE KNEE JOINT
269
membranosus and internal lateral ligament. Superficially, an oblique fasciculus
from the semimembranosus runs across the centre, passing upwards and outwards
from near the back part of the inner tuberosity of the tibia to the external condyle
of the femur where it joins the outer head of the gastrocnemius, a sesamoid plate
being sometimes developed at the point of junction. This slip greatly strengthens
the posterior ligament, of which, if not the chief constituent, it is at least a very
important part.
Its deep surface is closely connected with the semilunar cartilages (especially
the inner), and coronary ligaments, and in the interval between the cartilages with
FIG. 246.-ANTERIOR VIEW OF THE INTERNAL LIGAMENTS OF THE KNEE JOINT.
Aperture leading into-
the bursa beneath the
quadriceps extensor
Attachment of capsular,
or anterior ligament to
femur
Fatty tissue within cut
edge of ligamentum
mucosum
Posterior crucial
ligament
Anterior crucial
ligament
External semilunar.
fibro-cartilage
Coronary ligament
Internal semilunar
fibro-cartilage
Transverse ligament
Coronary ligament
the posterior crucial ligament and fibro-fatty tissue within the joint. Superficially
it forms part of the floor of the popliteal space.
The capsular or anterior ligament (fig. 246) is thin but strong, covering the
synovial membrane under the quadriceps extensor tendon, and looking like a loose
sac. It is attached to the femur near the articular margin on the inner side, but
further away on the outer; it passes beneath the external lateral ligament to join
the sheath of the popliteus. Internally it joins the internal lateral ligament. Below,
it is fixed to the upper and lateral borders of the patella and the anterior border
of the head of the tibia. It is strengthened superficially between the femur and
patella by an expansion from the subcrureus, and is separated from the fibrous

270
THE ARTICULATIONS
expansion of the extensor tendon by a layer of fatty tissue. The synovial membrane
lines its deep surface, and holds it against the borders of the semilunar cartilages;
it is also attached to the coronary ligaments.
The anterior crucial ligament (figs. 246 and 247) is strong and cord-like. It is
attached to the inner half of the fossa in front of the spine of the tibia, and to the
outer border of the inner articular facet as far back as the inner tubercle of the
spine. It passes upwards, backwards, and outwards to the back part of the in-
ternal surface of the external condyle. To the tibia, it is fixed behind the anterior
extremity of the internal semilunar cartilage. Behind and to the outer side it has
the anterior extremity of the external semilunar cartilage, a few fibres of which
blend with the outer edge of the ligament. Its anterior fibres at the tibial end are
strongest and longest, being fixed highest on the femur; while the posterior,
springing from the spine, are shorter and more oblique. Near the spine, a slip is
sometimes given off to the posterior crucial.
The posterior crucial ligament (figs. 246, 247, and 248) is stronger and less
oblique than the anterior. It is fixed below to the greater portion of the fossa
behind the spine of the tibia, especially the outer and posterior portion, and then
inwards and upwards along the popliteal notch; being joined by fibres which arise
FIG. 247.-STRUCTURES LYING ON THE HEAD OF THE TIBIA. (Right knee.)
Ligamentum patellæ
Transverse ligament
Anterior crucial-
Internal semilunar-
fibro-cartilage
Posterior crucial.
ligament
Expansion from quadriceps
extensor tendon
External semilunar fibro-
cartilage
Tendon of biceps
External lateral
ligament
between the tubercles of the spine, it ascends to the anterior part of the outer
surface of the inner condyle, having a wide crescentic attachment more than half
an inch (1.5 cm.) in extent just above the articular surface. Behind, it is connected
at the tibia directly with the posterior ligament, and a little higher up by means
of a quantity of interposed areolar tissue. In front it rests upon the posterior
horn of the internal semilunar cartilage, and receives a large slip from the external
cartilage, which runs up along it either in front, or behind to the femur; higher
up in front it is connected with the anterior crucial ligament.
Until they rise above the spine of the tibia the two crucial ligaments are closely
bound together, so that no interspace exists between their tibial attachments and
the point of decussation; the only space between them is therefore a V-shaped
one corresponding to the upper half of their X-shaped arrangement, and this is a
mere chink in the undissected state, and can be seen from the front only, owing to
the fatty tissue beneath the synovial membrane which surrounds their femoral
attachment.
The interarticular or semilunar fibro-cartilages (figs. 246, 247) are two cre-
scentic plates resting upon the circumferential portions of the articular facets of the

THE KNEE JOINT
271
tibia, and moving with the tibia upon the femur. They somewhat deepen the tibial
articular surfaces, and are dense and compact in structure, becoming looser and
more fibrous near their extremities, where they are firmly fixed in front of and
behind the spine of the tibia. The circumferential border of each is convex, thick,
and somewhat loosely attached to the borders of the tuberosities of the tibia by the
coronary ligaments, and the reflexion of the synovial membrane. The inner border
is concave, thin, and free. Half an inch (1.3 cm.) broad at the widest part, they
taper somewhat towards their extremities, and cover rather less than two-thirds of
the articular facets of the tibia. Their upper surfaces are slightly concave, and fit
on to the femoral condyles, while the lower are flat and rest on the head of the
tibia; both surfaces are smooth and covered by synovial membrane.
FIG. 248.-ANTERIOR VIEW OF THE KNEE JOINT, SHOWING THE SYNOVIAL LIGAMENTS.
(Anterior portion of capsule with the extensor tendon thrown downwards.)
Posterior crucial.
Ligamentum mucosum.
Alar ligament
Alar ligament
Synovial pouch under ten-
don of quadriceps extensor
The external semilunar cartilage (fig. 247) is nearly circular in form and less
firmly fixed than the internal, and consequently slides more freely upon the tibia.
Its anterior cornu is attached to a narrow depression along the outer articular facet,
just in front of the external tubercle of the tibial spine, close to, and on the outer
side of, the anterior crucial ligament; a small slip from the cornu is often fixed to
the tibia in front of the crucial ligament. The posterior cornu is firmly attached to
the tibia behind the external tubercle of the spine, blending with the posterior
crucial ligament, and giving off a well-marked fasciculus, which runs up along the
anterior border of the ligament to be attached to the femur (ligament of Wrisberg).
It also sends a narrow slip into the back part of the anterior crucial ligament.
Its outer border is grooved towards its posterior part by the popliteus tendon,
which is held to it by fibrous tissue and synovial membrane, and separates it from

272
THE ARTICULATIONS
the external lateral ligament. From its anterior border is given off the transverse
ligament.
The internal semilunar cartilage (fig. 247) is a segment of a larger circle than the
external, and has an outline more oval than circular. Its anterior cornu is wide, and
has a broad and oblique attachment to the anterior margin of the head of the tibia.
It reaches backwards and outwards from the margin of the tuberosity towards the
middle of the fossa in front of the tibial spine, being altogether in front of the
anterior crucial ligament. The posterior cornu is firmly fixed by a broad insertion in
an antero-posterior line along the inner side of the posterior fossa, from the internal
tubercle of the spine to the posterior margin of the head of the tibia, Its convex
border is connected with the internal lateral ligament and the semimembranosus
tendon.
The transverse ligament (figs. 246 and 247) is a rounded, slender, short cord,
which extends from the convex border of the external semilunar cartilage to the
concave border or anterior cornu of the internal, near which it is sometimes attached
to the bone. It is an accessory band of the external cartilage, and is situated
beneath the synovial membrane.
The coronary ligaments (fig. 246) connect the margins of the semilunar
fibro-cartilages with the head of the tibia. The external is much more lax
than the internal, permitting the outer cartilage to change its position more freely
than the inner. They are not in reality separate structures, but consist of fibres
of the several surrounding ligaments of the knee joint which become attached to,
as they pass over the margins of the fibro-cartilages.
The synovial membrane (fig. 249) of the knee forms the largest synovial sac in
the body. Bulging upwards from the patella, it follows the capsule of the joint
into a large cul-de-sac beneath the tendon of the extensor muscles on the front of
the femur. It reaches some distance beyond the articular surface of the bone,
and communicates very frequently with a large bursa interposed between the
tendon and the femur above the line of attachment of the capsular ligament.
After investing the circumference of the lower end of the femur, it is reflected
upon the fibrous envelope of the joint formed by the capsular, posterior, and
lateral ligaments. It covers a great portion of the crucial ligaments, but leaves
uncovered the back of the posterior crucial where the latter is connected with
the posterior ligament, and the lower part of both crucial ligaments where
they are united. Thus the ligaments are completely shut out of the synovial cavity.
Along the fibrous envelope the synovial membrane is conducted down to the semi-
lunar cartilages, over both surfaces of which it passes, and is reflected off the under
surface on to the coronary ligaments, and thence down to the head of the tibia,
around the circumference of which it extends a short way. It dips down between
the external cartilage and the head of the tibia as low as the superior tibio-fibular
ligament, reaching inwards nearly as far as the popliteal notch, and forming a
bursa for the play of the popliteal tendon.
At the back of the joint two pouches are prolonged beneath the muscles, one on
each side between the condyle of the femur and the origin of the gastrocnemius.
Large processes of synovial membrane also project into the joint, and being
occupied by fat serve as padding to fill up spaces. The chief of these processes,
the ligamentum mucosum (figs. 248 and 249) springs from the infrapatellar fatty
mass. This so-called ligament is the central portion of the large process of
synovial membrane, of which the alar ligaments form the lateral free margins. It
extends from the fatty mass, below the patella, backwards and upwards to the
intercondyloid notch of the femur, where it is attached in front of the anterior
crucial, and to the outer side of the posterior crucial ligament. Near the femur.
it is thin and transparent, consisting of a double fold of synovial membrane, but
near the patella it contains some fatty tissue. Its anterior or upper edge is free,

THE KNEE JOINT
273
and fully an inch (2.5 cm.) long; the posterior or lower edge is half the length,
and is attached to the crucial ligaments above, but is free below.
Passing backwards from the capsule on each side of the patella is a prominent
crescentic fold formed by reduplications of the synovial membrane-these are the
alar ligaments (fig. 248). Their free
Their free margins are concave and thin, and are lost
below in the ligamentum mucosum. There is a slight fossa above and another
below each ligament.
FIG. 249.-VERTICAL SECTION OF THE KNEE JOINT IN THE ANTERO-POSTERIOR DIRECTION*

Muscular fibres of quadriceps
extensor
Extension of synovial sac
of knee upon femur
Tendon of quadriceps ex-
tensor, forming fibrous
capsule of joint
PATELLA
Fatty tissue.
Opening in synovial
membrane behind
crucial ligament
leading into inner
half of joint
Synovial membrane.
reflected off crucials
Cut end of anterior.
'crucial ligament
Posterior crucial-
ligament
Ligament of-
Winslow
Pre-patellar bursa
-CONDYLE OF FEMUR
(INNER)
Ligamentum
mucosum
-Fatty tissue between
ligamentum patellæ
and synovial sac
Bursa beneath ligamentum
patellæ
TIBIA
The arterial supply is derived from the anastomotica femoris; the superior and
inferior internal and external articular; the azygos articular; the descending
branch of the external circumflex; the anterior recurrent branch from the anterior
tibial; and the posterior tibial recurrent.
The nerve-supply comes from the great sciatic, anterior crural, and obturator
sources. The great sciatic gives off the internal and external popliteal; the internal
popliteal sends two, sometimes three branches-one with the azygos artery; one
T

274
THE ARTICULATIONS
with the inferior internal, and sometimes one with the superior internal articular
artery; the external popliteal gives a branch which accompanies the superior, and
another which accompanies the inferior articular artery, and a recurrent branch
which follows the course of the anterior recurrent branch of the anterior tibial
FIG. 250,-THE LATERAL LIGAMENTS OF THE KNEE IN FLEXION AND EXTENSION.
A
C
D
B
artery. The anterior crural sends an articular branch from the nerve to the
vastus externus; a second from the nerve to the vastus internus; and sometimes
a third from that to the crureus. Thus there are three articular twigs to the
knee derived from the muscular branches of the anterior crural (Roger Williams,
Journ. Anat. Physiol., 1874). The obturator by its deep division sends a branch
THE KNEE JOINT
275
through the adductor magnus on to the popliteal artery, which enters the joint
through the posterior ligament.
The movements which occur at the knee joint are flexion and extension, with
some slight amount of pronation and supination in the bent position. These
movements are not so simple as the corresponding ones at the elbow, for the knee
is not a simple hinge joint, and pronation and supination, instead of occurring
between the tibia and fibula, as between the radius and ulna, are movements of the
tibia with the fibula upon the condyles of the femur.
The knee differs from a true hinge joint, like the elbow or ankle, in the following
particulars:-
1. The points of contact of the femur with the tibia are constantly changing.
Thus, in the flexed position, the hinder part of the articular surface of the tibia is
in contact with the rounded back part of the condyles; in the semiflexed position
FIG. 251.-SECTION OF KNEE, SHOWING CRUCIALS IN EXTENSION.

Anterior crucial.
SPINE OF TIBIA-
Transverse ligament
Slip from external fibro-
cartilage to femur (liga-
ment of Wrisberg)
Posterior crucial ligament
External semilunar cartilage
Coronary ligament
Antero-superior tibio-fibular
figament
the middle parts of the tibial facets articulate with the anterior rounded part of the
condyles; while in the fully extended position the anterior and middle parts of the
tibial facets are in contact with the flattened anterior portion of the condyles. So
with the patella: in extreme flexion the inner articular facet rests on the outer
part of the internal condyle of the femur; in flexion the upper pair of facets rest
on the lower part of the trochlear surface of the femur; in mid-flexion the middle
pair rest on the middle of the trochlear surface; while in extension the lower pair of
facets on the patella rest on the upper portion of the trochlear surface of the femur.
This difference may be described as the shifting of the points of contact of the
articular surface.
2. It differs from a true hinge in that, in passing from a state of extension to
one of flexion, the tibia does not revolve round a single transverse axis drawn
through the lower end of the femur, as the ulna does round the lower end of the
T2

276
THE ARTICULATIONS
humerus. The articular surface of the tibia slides forwards in extension and
backwards in flexion; thus the axis round which the tibia revolves upon the
femur is a shifting one, as is seen by reference to fig. 250, B, C, D.
3. Another point of difference is that extension is accompanied by rotation
outwards, and flexion by rotation inwards. This rotation occurs round a vertical
axis drawn through the middle of the outer condyle of the femur and the outer
tuberosity of the tibia, and is most marked at the termination of extension and at
the commencement of flexion. This rotation of the leg at the knee is a true
rotation about a vertical axis, and thus differs from the obliquity of the flexion and
extension movements at the elbow which is due to the oblique direction of the
articular surfaces of the bones.
4. The antero-posterior spiral curve of the femoral condyles is such, that the
anterior part is an arc of a greater circle than the posterior; hence certain ligaments
which are tightened during extension are relaxed during flexion, and thereby a
FIG. 252.-CRUCIAL LIGAMENTS IN FLEXION.
Posterior crucial
Anterior crucial
Internal semilunar
cartilage
Transverse ligament
-Slip from external cartilage to femur
-External semilunar cartilage
-Coronary ligament
-Antero-superior tibio-fibular ligament
considerable amount of rotatory movement is permitted in the flexed position.
This is called pronation and supination. The axis of this rotation is vertical, and
passes through the inner tubercle of the spine of the tibia, so that the outer
tuberosity moves in the arc of a larger circle than does the inner, and is therefore
required to move more freely and easily; hence the shape of the external articular
facet and the loose connection of the external semilunar cartilage which is adapted
to it.
In extension, all the ligaments are on the stretch with the exception of the
ligamentum patellæ and front of the capsule. Extension is checked by both the
crucial ligaments and the lateral ligaments (figs. 250, A, B, and 251).
In flexion the ligamentum patellæ and anterior portion of the capsule are on
the stretch; so also is the posterior crucial in extreme flexion, though it is not
quite tight in the semiflexed state of the joint. All the other ligaments are
relaxed (fig. 250, C, D), although the relaxation of the anterior crucial ligament is

THE KNEE JOINT
277
slight in extreme flexion (fig. 252). Flexion is only checked during life by the
contact of the soft parts, i.e. the calf with the back of the thigh.
Pronation, or inward rotation, is checked by the anterior crucial ligament; the
lateral ligaments being loose.
Supination, or outward rotation, is checked by the lateral ligaments; the crucial
ligaments have no controlling effect on it, as they are untwisted by it.
Sliding movements are checked by the crucials and lateral ligaments-sliding
forwards especially by the anterior, and sliding backwards by the posterior crucial.
3. THE TIBIO-FIBULAR UNION
The fibula is connected with the tibia throughout its length by an interosseous
membrane, and at the upper and lower extremities by means of two joints. Very
little movement is permitted between the two bones.
(a) The superior tibio-fibular joint.
(b) The middle tibio-fibular union.
(c) The inferior tibio-fibular joint.
(a) THE SUPERIOR TIBIO-FIBULAR JOINT
Class.-Diarthrosis.
Subdivision.-Arthrodia.
The superior tibio-fibular joint is about a quarter of an inch (6 mm) below, and
quite distinct from, the knee at its upper and anterior part; but at its posterior and
superior aspect, where the border of the outer tuberosity of the tibia is bevelled
by the popliteus muscle, the joint is in the closest proximity to the bursa beneath
the tendon of that muscle, and is only separated from the knee-joint by a thin
septum of areolar tissue. There is often a communication between the synovial
cavities of the two joints. The ligaments uniting the bones are:-
Capsular.

Anterior tibio-fibular.
Posterior tibio-fibular.
The capsular ligament is a well-marked fibro-areolar structure; it is attached
close round the articular margins of the tibia and fibula, on the latter bone
extending a little distance from the margin behind and below. In front it is shut
off completely from the knee-joint by the capsule of the knee and the coronary
ligament; but behind, it is often very thin, and may communicate with the bursa
under the popliteus tendon.
The anterior tibio-fibular ligament (fig. 251) consists of a few fibres which
pass upwards and inwards from the fibula to the tibia. It lies beneath the
anterior portion of the tendon of the biceps.
The posterior tibio-fibular ligament (fig. 245) consists of a few fibres which
pass upwards and inwards between the adjacent bones, from the head of the fibula
to the outer tuberosity of the tibia.
The superior interosseous ligament consists of a mass of dense yellow fibro-
areolar tissue, binding the opposed surfaces of the bones together for three-quarters
of an inch (2 cm.) below the articular facets. It is continuous with the interosseous
membrane along the tibia.
The biceps tendon is divided by the long external lateral ligament of the knee;
of the two divisions the anterior is by far the stronger, and is attached to the
external tuberosity of the tibia as well as to the front of the head of the fibula, and
thus the muscle, acting on both bones, tends to brace them tighter together; indeed,
it holds the bones strongly together after all other connections have been severed.


278
THE ARTICULATIONS
The synovial membrane which lines the joint sometimes communicates with
the knee joint through the bursa beneath the popliteus tendon.
The arterial supply is from the inferior external articular and recurrent tibial
arteries.
The nerve-supply is from the inferior external articular, and also from the
recurrent branch of the external popliteal.
The movements are but slight, and consist merely of a gliding of the two bones
upon one another. The joint is so constructed that the fibula gives some support
to the tibia in transmitting the weight to the foot. The articular facet of the
tibia overhangs, and is received upon the articular facet of the head of the
fibula in an oblique plane. This joint allows of slight yielding of the external
malleolus during flexion and extension of the ankle joint, the whole fibula gliding
slightly upwards in flexion, and downwards in extension of the ankle.
(b) THE MIDDLE TIBIO-FIBULAR UNION
The interosseous membrane is attached all along the outer border of the tibia and
the interosseous border of the fibula. It is deficient above for about an inch (2.5 cm.)
or more, measured from the under aspect of the superior joint. Its upper border
is concave, and over it pass the anterior tibial vessels. The membrane consists of
a thin aponeurotic and translucent lamina, formed of oblique fine fibres, some of
which run from the tibia to the fibula, and some from the fibula to the tibia, but
all are inclined downwards. They are best marked at their attachment to the
bones, and gradually grow denser and thicker as they approach the inferior
interosseous ligament. The chief use of the membrane is to afford a surface for the
origin of muscles. It is continuous below with the inferior interosseous ligament.
(c) THE INFERIOR TIBIO-FIBULAR ARTICULATION
Class.--Diarthrosis.
Subdivision.-Arthrodia.
This junction is formed by the lower ends of the tibia and fibula. The rough
triangular surface on each of these bones formed by the bifurcation of their inter-
osseous lines is closely and firmly united by the inferior interosseous ligament.
The fibula is in actual contact with the tibia by an articular facet, which is small
in size, crescentic in shape, and continuous with the articular facet of the malleolus.
The ligaments which unite the bones are:-
1. Anterior inferior tibio-fibular ligament.
2. Posterior inferior tibio-fibular ligament.
3. Transverse ligament.
4. Inferior interosseous ligament.
The anterior inferior tibio-fibular ligament (fig. 255) is a strong triangular band
about three-quarters of an inch (2 cm.) wide, and is attached to the lower extremity of
the tibia at its anterior and external angle, close to the margin of the facet for the
astragalus, and passes downwards and outwards to the anterior border and con-
tiguous surface of the lower end of the fibula, some fibres passing along the edge
nearly as far as the origin of the anterior fasciculus of the external lateral liga-
ment. The fibres increase in length from above downwards. In front it is in relation
with the peroneus tertius and deep fascia of the leg, and gives origin to fibres
of the anterior ligament of the ankle joint. Behind, it lies in contact with the
interosseous ligament, and comes into contact with the articular surface of the
astragalus.
The posterior inferior tibio-fibular ligament (figs. 254, 255) is very similar to
THE TIBIO-FIBULAR UNION
279
the anterior, extending from the posterior and external angle of the lower end
of the tibia downwards and outwards to the lowest half-inch (1.5 cm.) of the border
separating the internal from the posterior surface of the shaft of the fibula, and to
the upper part of the posterior border of the external malleolus. It is in relation
in front with the interosseous ligament; below, it touches the transverse ligament.
The inferior interosseous ligament is a dense mass of short felt-like fibres,
passing transversely between and firmly uniting the opposed rough triangular
surfaces at the lower ends of the tibia and fibula, except for three-eighths of an
inch (1 cm.) at the extremity, where there is a synovial cavity. It extends from
the anterior to the posterior tibio-fibular ligaments, reaching upwards an inch and
a half in front (4 cm.), but only half this height behind.
The transverse ligament (fig. 254) is a strong rounded band, attached to nearly
the whole length of the inferior border of the posterior surface of the tibia, just above
the articular facet for the astragalus. It then inclines a little forwards and down-
wards, to be attached to the internal surface of the external malleolus, just above
the fossa, and also into the upper part of the fossa itself.
The synovial membrane is continuous with that of the ankle-joint; it projects
upwards between the bones beyond their articular facets as high as the inferior
interosseous ligament.
The nerve-supply is the same as that of the ankle-joint; the arterial supply is
from the peroneal and the anterior peroneal, and sometimes from the anterior
tibial, or its external malleolar branch.
The movement permitted at this joint is a mere gliding, chiefly in an upward
and downward direction, of the fibula on the tibia. The bones are firmly braced
together and yet form a slightly yielding arch, thus allowing a slight lateral
expansion during extreme flexion, when the broad part of the astragalus is brought
under the arch, by the upward gliding of the fibula on the tibia. To this end the
direction of the fibres of the superior and inferior tibio-fibular ligaments is down-
wards from tibia to fibula. This mechanical arrangement secures perfect contact
of the articular surfaces of the ankle joint in all positions of the foot.

4. THE ANKLE JOINT
Class.-Diarthrosis.
Subdivision.-Ginglymus.
The ankle is a perfect ginglymus or hinge joint. The bones which enter into
its formation are: the lower extremity and internal malleolus of the tibia, and
the external malleolus of the fibula, above; and the upper and lateral articular
surfaces of the astragalus below. The ligaments uniting the bones are:-

Anterior.
Posterior.
Internal lateral.
External lateral.
The anterior ligament (figs. 253, 255) is a thin membranous structure, which
extends between the lateral ligaments. It is attached above to the anterior border
of the internal malleolus, to a crest of bone just above the transverse groove at the
lower end of the tibia, to the anterior inferior tibio-fibular ligament, and to the
anterior border of the external malleolus. Below, it is attached to the rough upper
surface of the neck of the astragalus, in front of the fossa. Internally it is thicker,
and is fixed to the astragalus close to the facet for the inner malleolus, being
continuous with the internal lateral ligament, and passing forwards to blend
with the dorsal astragalo-scaphoid ligament. Externally it is attached to the
astragalus, just below and in front of the angle between the superior and lateral
facets, close to their edges, and joins the anterior fasciculus of the external lateral
ligament. It is in relation, in front with the tibialis anticus muscle, the anterior

280
THE ARTICULATIONS
tibial vessels and nerve, the extensor tendons of the toes, and the peroneus tertius;
and behind with a mass of fat and synovial membrane.
The posterior ligament (fig. 254) is a very thin and disconnected membranous
structure, connected above with the external malleolus, internal to the peroneal
groove; to the posterior margin of the lower end of the tibia external to the groove
for the tibialis posticus; and to the posterior inferior tibio-fibular ligament. Below,
it is attached to the posterior surface of the astragalus from the internal to the
external ligaments. The passage of the flexor longus hallucis tendon over the back
of the joint serves the purpose of a much stronger posterior ligament.
The internal lateral or deltoid ligament (fig. 253) is attached superiorly to the
internal malleolus along its lower border, and to its anterior surface superficial
to the anterior ligament; some very strong fibres are fixed to the notch in the lower
border of the malleolus, and, getting attachment below to the rough depression on
FIG. 253.-INNER VIEW OF THE ANKLE AND THE TARSUS, SHOWING THE GROOVE
FOR THE TENDON OF THE TIBIALIS POSTICUS.
Int. lateral
ligament
Inferior
calcaneo-
scaphoid
ligament
Short plantar ligament Long plantar ligament
the inner side of the astragalus, form a deep portion to the ligament. The ligament
radiates; the posterior fibres are short, and incline a little backwards to be fixed
to the rough inner surface of the astragalus, close to the superior articular facet,
and into the tubercle to the inner side of the flexor longus pollicis groove. The
fibres next in front are numerous and form a thick and strong mass, filling up the
rough depression on the inner surface of the astragalus, whilst some pass over the
calcaneo-astragaloid joint to the upper and inner border of the sustentaculum tali.
The fibres, which are connected above with the anterior surface of the malleolus,
pass downwards and somewhat forwards to be attached to the scaphoid and to the
margin of the calcaneo-scaphoid ligament.
The external lateral ligament (figs. 254, 255) consists of three distinct slips.
The anterior fasciculus is ribbon-like and passes from the anterior border of the
external malleolus near the tip to the rough surface of the astragalus in front of the
THE ANKLE JOINT
281
external lateral facet, and overhanging the sinus pedis. The middle fasciculus is a
strong roundish bundle, which extends downwards and somewhat backwards from
the anterior border of the external malleolus close to the attachment of the anterior
fasciculus, and from the outer surface of the malleolus, just in front of the apex,
to a tubercle on the middle of the outer surface of the calcaneum. The posterior
fasciculus is almost horizontal; it is a strong, thick band attached at one end to
the posterior border of the malleolus, and slightly to the fossa on the internal
surface; and at the other end to the astragalus, behind the articular facet for the
fibula, as well as to a tubercle on the outer side of the groove for the flexor longus
hallucis. The middle fasciculus is covered by the tendons of the peronei longus
and brevis; and in extension, the posterior fasciculus is received into the pit on
the inner surface of the external malleolus.
FIG. 254.-LIGAMENTS SEEN FROM THE BACK OF THE ANKLE JOINT.

The lower part of the inter-
Osseous membrane seen be-
tween the bones
Posterior ligament of ankle
joint
Posterior part of the internal-
lateral ligament
Transverse ligament of inferior
tibio-fibular joint
-Posterior fasciculus of
external lateral ligament
Middle fasciculus of external
lateral ligament
The synovial membrane is very extensive. Besides lining the ligaments of the
ankle, it extends upwards between the tibia and fibula, forming a short cul-de-sac
as far as the interosseous ligament. Upon the anterior and posterior ligaments it is
very loose, and extends beyond the limits of the articulation. It is said to contain
more synovia than any other joint.
The nerve-supply is from the internal saphenous, posterior tibial, and the
external division of the anterior tibial.
The arterial supply comes from the anterior tibial, the anterior peroneal, the
external malleolar, the posterior tibial, and posterior peroneal.
Movements. This being a true hinge-joint, flexion and extension are the only
movements of which it is capable, there being no lateral motion, except in extreme
extension, when the narrowest part of the astragalus is thrust forwards into the


282
THE ARTICULATIONS
widest part of the tibio-fibular arch. In flexion the astragalus is tightly embraced
by the malleoli, and lateral movement is impossible. Flexion is limited by: (i)
nearly the whole of the fibres of the internal lateral ligament, none but the most
anterior being relaxed; (ii) the posterior and middle portions of the external lateral
ligament, especially the posterior; (iii) the posterior ligament of the ankle. It is
also limited by the neck of the astragalus abutting on the edge of the tibia.
Extension is limited by: (i) the anterior fibres of the internal lateral ligament; (ii)
the anterior and middle portions of the external lateral ligament; (iii) the inner and
stronger fibres of the anterior ligament. It is also limited by the posterior portion
of the astragalus meeting with the tibia. Thus the middle portion of the external
lateral ligament is always on the stretch, owing to its obliquely backward direction,
whereby it limits flexion; and its attachment to the fibula in front of the malleolar
apex, whereby it prevents over-extension as soon as the foot begins to twist inwards.
This inward twisting, or adduction of the foot, is partly due to the greater posterior
length of the inner border of the superior articular surface of the astragalus, and to
the less proportionate height posteriorly of the external border of that surface, but
chiefly to the lateral movement in the calcaneo-astragaloid joints. Flexion and
extension take place round a transverse axis drawn through the body of the
astragalus. The movement is not in a direct antero-posterior plane, but on a plane
inclined forwards and outwards from the middle of the astragalus to the inter-
metatarsal joint of the second and third toes.
5. THE TARSAL JOINTS
These may again be divided up into the following sub-groups :-
(a) The calcaneo-astragaloid union.
(b) The articulations of the anterior portion of the tarsus.
(c) The medio-tarsal joint.
Class.
(a) THE CALCANEO-ASTRAGALOID UNION
Diarthrosis.
Subdivision.-Arthrodia.
There are two joints which enter into this union-viz. an anterior and a
posterior.
(i) The Posterior Calcaneo-astragaloid Joint
The calcaneum articulates with the astragalus by two joints, the anterior and
posterior: the former communicates with the medio-tarsal; the posterior is separate
and complete in itself. The two bones are united by the following ligaments:-
Interosseous.
External calcaneo-astragaloid.
Internal calcaneo-astragaloid.
Posterior calcaneo-astragaloid.
The interosseous ligament (figs. 255, 256) is a strong band connecting the apposed
surfaces of the calcaneum and astragalus along their oblique grooves. It is composed
of several vertical laminæ of fibres, with some fatty tissue in between. It is better
marked, deeper, and broader externally. Strong laminæ extend from the rough
inferior and external surfaces of the neck of the astragalus to the rough superior
surface of the os calcis anteriorly, forming the posterior boundary of the anterior
calcaneo-astragaloid joint; these have been described as the anterior interosseous
ligament. The posterior laminæ extend from the roof of the sinus pedis to
the os calcis immediately in front of the external facet, thus forming the anterior
part of the capsule of the posterior joint.
The external calcaneo-astragaloid ligament (fig. 255) extends from the groove
just below and in front of the external articular facet of the astragalus to the os calcis

THE TARSAL JOINTS
283
some little distance from the articular margin. Its fibres are nearly parallel with
those of the middle fasciculus of the external lateral ligament of the ankle, which
passes over it and adds to its strength. It fills up the interval between the middle
and anterior fasciculus of the external lateral ligament, a considerable bundle of its
fibres blending with the anterior border of the middle fasciculus.
The posterior calcaneo-astragaloid ligament passes from the external tubercle
and lower edge of the groove for the flexor longus hallucis to the os calcis, a
variable distance from the articular margin.
The internal calcaneo-astragaloid ligament (fig. 253) is a narrow band of well-
marked fibres passing obliquely downwards and backwards from the depression on
the astragalus, just behind the inner end of the sinus pedis, to the os calcis behind
the sustentaculum tali, thus completing the floor of the groove.
The synovial sac is distinct from any other.
The nerve-supply is from the posterior tibial or one of its plantar branches.
The arteries are, a branch from the posterior tibial, which enters at the inner
end of the sinus pedis; and twigs from the tarsal, external malleolar, and the
peroneal, which enter at the outer end of the sinus.
(ii) The Anterior Calcaneo-astragaloid Joint
This joint is formed by the anterior facet on the upper surface of the os calcis
and the facets on the lower surface of the neck and head of the astragalus; it is
bounded laterally and behind by ligaments, and communicates anteriorly with the
astragalo-scaphoid joint. The ligaments are:-

Interosseous.
Internal (or antero-internal) calcaneo-astragaloid.
External calcaneo-scaphoid.
The interosseous ligament by its anterior laminæ limits this joint posteriorly.
It has been already described (p. 282).
The antero-internal calcaneo-astragaloid ligament consists of short fibres
attached above to the rough depression on the internal surface of the neck of the
astragalus, and below to the upper edge of the free border of the sustentaculum
tali, blending posteriorly with the inner extremity of the interosseous ligament, and
anteriorly with the upper border of the inferior calcaneo-scaphoid ligament. It is
strengthened by the internal lateral ligament, the anterior fibres of which are also
attached to the inferior calcaneo-scaphoid ligament.
The external calcaneo-scaphoid (superior calcaneo-scaphoid, Gray) (figs. 255,
256) limits this, as well as the astragalo-scaphoid joint, on the outer side. It
is a strong, well-marked band, extending from the rough upper surface of the
calcaneum, external to the anterior facet, to a slight groove on the outer surface of
the scaphoid near the posterior margin. It blends below with the inferior calcaneo-
scaphoid, and above with the astragalo-scaphoid ligament. Its fibres run obliquely
forwards and inwards. The internal lateral and middle fasciculus of the external
lateral ligaments of the ankle joint also add to the security of these two joints, and
assist in limiting movements between the bones by passing over the astragalus to
the os calcis.
The movements of which these two joints are capable are adduction and abduc-
tion, with some amount of rotation. Adduction, or inclination of the sole inwards,
being combined with some rotation of the toes inwards, and of the heel outwards;
while abduction, or inclination of the foot outwards, is associated with turning of
the toes outwards and the heel inwards. Thus the variety and the range of move-
ments of the foot on the leg, which at the ankle are almost limited to flexion and
extension, are increased. The cuboid moves with the calcaneum, while the scaphoid
revolves on the head of the astragalus.

284
THE ARTICULATIONS
In walking, the heel is first placed on the ground; the foot is slightly adducted;
but as the body swings forwards, first the outer then the inner toes touch the ground,
the astragalus presses against the scaphoid and sinks upon the spring ligament;
the foot then becomes slightly abducted. When the foot is firmly placed on the
ground, the weight is transmitted to it obliquely downwards and inwards, so that
if the ligaments between the calcaneum and astragalus did not check abduction,
inward displacement of the astragalus from the tibio-fibular arch would only be
prevented by the tendons passing round the inner ankle (especially the tibialis
posticus). If the ligaments be too weak to limit abduction, the weight of the body
increases it, and forces the inner malleolus and astragalus downwards and inwards,
giving rise to flat foot.
FIG. 255.-EXTERNAL VIEW OF THE LIGAMENTS OF THE FOOT AND ANKLE.
Anterior inferior tibio-fibular
ligament
Anterior ligament of ankle-joint,
Outer extremity of the
interosseous ligament
Postero-inferior tibio-fibular
ligament
Fasciculus of posterior
ligament of ankle
External calcaneo-
scaphoid ligament
Dorsal cubo-scaphoid ligament
Internal calcaneo-cuboid
Posterior fasciculus of
external lateral ligament
Dorsal External Middle fasciculus of external lateral
calcaneo-
ligament of the ankle
cuboid
calcaneo-
astragaloid
ligament
The advantages of the obliquity and peculiar arrangement of the posterior
calcaneo-astragaloid articulation are seen in walking: (i) for the posterior facet of
the calcaneum receives the whole weight of the body when the heel is first placed
on the ground; (ii) by the upward pressure of this facet against the astragalus it
transfers the weight to the ball of the toes as the heel is raised, the hinder edge of
the sustentaculum tali and the anterior and outer part of the upper surface of
the calcaneum preventing the astragalus from being displaced too far forward by
the superincumbent weight; and (iii) the calcaneum serves to suspend the
astragalus when, with the heel raised by muscular action, the other foot is being
swung forwards.

THE TARSAL JOINTS
285
The synovial membrane is the same as that of the astragalo-scaphoid joint.
The arteries and nerves are derived from the same sources as those of the medio-
tarsal joints.
(b) THE ARTICULATIONS OF THE ANTERIOR PART OF THE TARSUS
Class.-Diarthrosis.
Subdivision.-Arthrodia.
These include (i) the cubo-scaphoid; (ii) scapho-cuneiform; (iii) intercunei-
form; and (iv) cubo-cuneiform joints.
(i) The Cubo-scaphoid Union
The ligaments which unite the cuboid and scaphoid are:-
Dorsal.
Interosseous.
Plantar.
The dorsal cubo-scaphoid ligament (fig. 256) runs forwards and outwards from
the outer end of the dorsal surface of the scaphoid to the middle third of the inner
border of the cuboid on its dorsal aspect, passing over the posterior external angle
of the external cuneiform bone. It is wider externally.
The plantar cubo-scaphoid ligament is a well-marked strong band, which runs
forwards and outwards, from the plantar surface of the scaphoid to the depression
on the inner surface of the cuboid, and slightly into the plantar surface just below it.
The interosseous cubo-scaphoid ligament is a strong band which passes between
the apposed surfaces of these bones from the dorsal to the plantar ligaments.
Some of its posterior fibres reach the plantar surface of the foot behind the cubo-
scaphoid ligament, and radiate outwards and backwards over the inner border of
the cuboid to blend with the anterior extremity of the short calcaneo-cuboid
ligament.

(ii) The Scapho-cuneiform Articulation
The ligaments uniting the scaphoid with the three cuneiform bones are:-
Dorsal.
Internal.
Plantar.
The dorsal scapho-cuneiform ligament is very strong, and stretches as a con-
tinuous structure on the dorsal surface of the scaphoid, between the tubercle of the
scaphoid on the inner side, and the dorsal cubo-scaphoid ligament externally, passing
forwards and a little outwards to the dorsal surfaces of the three cuneiform bones.
The internal scapho-cuneiform ligament is a very strong thick band which
connects the tubercle of the scaphoid with the inner surface of the internal cunei-
form bone. It is continuous with the dorsal and plantar ligaments. Its lower
border touches the tendon of the tibialis posticus.
The plantar scapho-cuneiform ligament forms, like the dorsal, a continuous
structure extending between the plantar surfaces of the bones. Its fibres pass
forwards and outwards. It is in relation below with the tendon of the tibialis
posticus.
It must be noticed that the expanded tendon of insertion of the tibialis posticus, and
the ligaments uniting the scaphoid with the cuboid and cuneiform bones pass forwards and
outwards, while the peroneus longus tendon and the ligaments uniting the first and second
rows of bones, except the inner half of the dorsal astragalo-scaphoid ligaments, pass forwards
and inwards. This arrangement is admirably adapted to preserve the arches of the foot,
and especially the transverse arch. Had these tendons and ligaments run directly forward,
all the strain on the transverse arch would have fallen on the interosseous ligaments, but
as it is, the arch is braced up by the above-mentioned structures.

286
THE ARTICULATIONS
(iii) The Intercuneiform and (iv) The Cubo-cuneiform Articulations
The uniting ligaments of these bones are divided into three sets:-
Dorsal.
Interosseous.
Plantar.
The dorsal ligaments are three in number, two connecting the three cuneiform
bones together, and a third uniting the external cuneiform with the cuboid. They
pass between the contiguous margins of the bones, and are blended behind with
the dorsal ligaments of the cubo-scaphoid and scapho-cuneiform joints.
The plantar ligaments are two in number: a very strong one passes outwards
and forwards from the outer side of the base of the internal cuneiform to the apex
of the middle cuneiform, winding somewhat to its outer side. The second connects
the apex of the external cuneiform with the anterior half of the inner surface of
the cuboid along its plantar border, joining behind with the plantar scapho-cuboid
ligament.
The interosseous ligaments are three in number. They are strong and deep
masses of ligamentous tissue which connect the middle cuneiform with the internal
and external cuneiform bones, and the external cuneiform with the cuboid;
occupying all the non-articular portions of the apposed surfaces of the bones.
The ligaments extend the whole vertical depth between the middle cuneiform and
the external, and the external cuneiform and the cuboid, and blend with the dorsal
and plantar ligaments; they are situated in front of the articular facets, and
completely shut off the synovial cavity behind from that in front. The ligament
between the internal and middle cuneiform bones occupies the inferior and
anterior two-thirds of the apposed surfaces, and does not generally extend high
enough to separate the synovial cavity of the anterior tarsal joint from that of the
second and third metatarsal and cuneiform bones. If it does extend to the dorsal
surface, it divides the facets completely from one another, making a seventh synovial
sac in the foot.
The synovial cavity will be described later on.
The arterial supply is from the metatarsal and plantar arteries.
The nerves are derived from the anterior tibial, and internal and external plantar.
The movement permitted in these joints is very limited, and exists only for
the purpose of adding to the general pliancy and elasticity of the tarsus without
allowing any sensible alteration in the position of the different parts of the foot,
as the medio-tarsal and calcaneo-astragaloid joints do. It is simply a gliding
motion, and either deepens or widens the transverse arch. The external cuneiform
being wedged in between the others is less movable, and so forms a pivot upon
which the rest can move. The movement is more produced by the weight of the
body than by direct muscular action; and of the muscles attached to this part of
the tarsus, all deepen the arch save the tibialis anticus, which pulls the internal
cuneiform up, and so tends to widen it.
(c) THE MEDIO-TARSAL OR TRANSVERSE TARSAL JOINTS
The articulations of the anterior and posterior portions of the tarsus, although
in the same transverse line, consist of two separate joints, viz. (i) an inner, the
astragalo-scaphoid, which communicates with the anterior calcaneo-astragaloid
articulation; and (ii) an outer, the calcaneo-cuboid, which is complete in itself.
The movements of the anterior upon the posterior portions of the foot take place at
both of these joints simultaneously. It will be most convenient to deal with the
joints separately as regards the ligaments; while the arteries, nerves, and move-
ments will be considered together.
THE TARSAL JOINTS
287
(i) The Astragalo-scaphoid Articulation
This is the only ball-and-socket joint in the tarsus. It communicates with the
anterior calcaneo-astragaloid articulation, and two of the ligaments which close it
in do not touch the astragalus, but pass from the calcaneum to the scaphoid. The
uniting ligaments are:-
External calcaneo-scaphoid.
Inferior calcaneo-scaphoid.
Astragalo-scaphoid.
The external calcaneo-scaphoid has been already described (page 283).
The inferior calcaneo-scaphoid ligament (figs. 256, 257) is an exceedingly dense
thick plate of fibrous tissue. It extends from the sustentaculum tali and the
FIG. 256.-VIEW OF THE FOOT FROM ABOVE, WITH THE ASTRAGALUS REMOVED TO SHOW
THE INFERIOR AND EXTERNAL CALCANEO-SCAPHOID LIGAMENTS.

Dorsal cubo-scaphoid
ligament
Dorsal calcaneo-cuboid
ligament
Internal calcaneo-cuboid
ligament
External calcaneo-scaphoid
ligament
ligament
Inferior calcaneo-scaphoid
Tendon of tibialis posticus
Cut edge of interosseous
ligament
under surface of the calcaneum in front of a ridge curving outwards to the
anterior tubercle of that bone, to the whole width of the under surface of the
scaphoid, and also to the inner surface of the scaphoid behind the tubercle. Inter-
nally it is blended with the anterior portion of the internal lateral ligament of
the ankle, and externally with the lower border of the external calcaneo-scaphoid
ligament. It is thickest along the inner border. Here it loses the well-marked
fibrous appearance which it has in the sole, and becomes smooth and faceted.
Over this part of the ligament the tendon of the tibialis posticus passes, giving
considerable support to the head of the astragalus by assisting the power and
spring of the ligament. The fibres of the ligament run forwards and inwards.
The astragalo-scaphoid ligament is a broad, thin, but well-marked layer of fibres
which passes from the dorsal and external surfaces of the neck of the astragalus to


288
THE ARTICULATIONS
the whole length of the dorsal surface of the scaphoid. Many of the fibres
Many of the fibres converge
to their insertion on the scaphoid. The fibres low down on the outer side blend a
little way from their origin with the upper edge of the external calcaneo-scaphoid
ligament, and then pass forwards and inwards to the scaphoid; those next above
pass obliquely and with a distinct twist over the upper and outer side of the head
of the astragalus to the centre of the dorsum of the scaphoid, overlapping fibres
from the inner side of the astragalus as well as some from the anterior ligament of
the ankle joint.
Synovial membrane. The astragalo-scaphoid is lined by the same synovial
membrane as the anterior calcaneo-astragaloid joint.
(ii) The Calcaneo-cuboid Articulation
Class.-Diarthrosis.
Subdivision.-Arthrodia.
The ligaments which unite the bones forming the outer part of the medio-tarsal
joint are:-
Internal or interosseous calcaneo-cuboid.
Long inferior calcaneo-cuboid.
Dorsal calcaneo-cuboid.
Short inferior calcaneo-cuboid.
The internal or interosseous calcaneo-cuboid ligament (fig. 256) is a strong
band of fibres attached to the os calcis along the inner part of the non-articular
ridge above the articular facet for the cuboid, and also to the upper part of the
internal surface close to the articular margin, and passes forwards to be attached
to the depression on the internal surface of the cuboid, and also to the rough angle
between the internal and inferior surfaces. At the calcaneum this ligament is
closely connected with the external calcaneo-scaphoid ligament. Towards the sole
it is connected with the short inferior calcaneo-cuboid ligament, and superiorly
with the dorsal calcaneo-cuboid.
The dorsal calcaneo-cuboid (fig. 256) is attached to the dorsal surfaces of the
two bones, extending low down externally to blend with the outer part of the
short plantar ligament. Over the inner half, or more, the ligament stretches some
distance beyond the margins of the articular surfaces, reaching well forward upon
the cuboid to be attached about midway between its anterior and posterior borders;
but towards the outer side, the ligament is much shorter, and is attached to the
cuboid behind its tubercle.
The long inferior calcaneo-cuboid (the long plantar) (fig. 257) is a strong
dense band of fibres which are attached posteriorly to the whole of the under
surface of the calcaneum between the posterior tubercles and the rounded eminence
(the anterior tubercle) at the anterior end of the bone. Most of its fibres pass
directly forwards, and are fixed to the outer two-thirds or more of the oblique.
ridge behind the peroneal groove on the cuboid, while some pass further forwards
and inwards, expanding into a broad layer, and are inserted into the bases of the
second, third, fourth, and inner half of the fifth metatarsal bones. This anterior
expanded portion completes the canal for the peroneus longus tendon, and from its
under surface arise the adductor hallucis and the flexor brevis minimi digiti
muscles.
The short inferior calcaneo-cuboid (short plantar) (fig. 257) is attached to the
rounded eminence (anterior tubercle) at the anterior end of the under surface of the
calcaneum, and to the bone in front of it, and then takes an oblique course forwards
and inwards, and is attached to the whole of the depressed inferior surface of the
cuboid behind the oblique ridge, except its outer angle. It is strongest near its outer
edge, and is formed by dense strong fibres.
The synovial membrane is distinct from that of any other tarsal joint.
The arterial supply of the medio-tarsal joints is from the anterior tibial from

MOVEMENTS AT THE TARSAL JOINTS
289
the tarsal and metatarsal branches of the dorsalis pedis, and from the plantar
arteries.
The nerve-supply of the medio-tarsal joints is from the external division of
the anterior tibial, and occasionally from the musculo-cutaneous or external
plantar.
The movements which take place at the medio-tarsal joints are mainly flexion
and extension, with superadded lateral and rotatory movements. Flexion at these
joints is simultaneous with extension of the ankle, and vice versa. Flexion and
extension do not take place upon a transverse, but round an oblique axis which
FIG. 257.-LIGAMENTS.

Long plantar or long
inferior calcaneo-cuboid
ligament
Tendon of peroneus longus
GROOVE FOR FLEXOR LONGUS
HALLUCIS
Inferior calcaneo-scaphoid
ligament
Short plantar or short
inferior calcaneo-cuboid
ligament
TUBERCLE OF SCAPHOID
INTERNAL CUNEIFORM
Insertion of peroneus
longus
passes from within outwards, and somewhat backwards and downwards through
the astragalus and calcaneum.
Combined with flexion and extension is also some rotatory motion round an
antero-posterior axis which turns the inner or outer border of the foot upwards.
There is also a fair amount of lateral motion whereby the foot can be inclined
inwards (i.e. adducted) or outwards (i.e. abducted).
These movements of the medio-tarsal joint occur in conjunction with those of
the ankle and calcaneo-astragaloid joints. Rotation at the calcaneo-astragaloid
joint is, however, round a vertical axis in a horizontal plane, and so turns the
toes inwards or outwards; whereas at the medio-tarsal union the axis is antero-
posterior and the inner or outer edge of the foot is turned upwards. Gliding at
the calcaneo-astragaloid joint elevates or depresses the edge of the foot, while at the
U

290
THE ARTICULATIONS
medio-tarsal it adducts or abducts the toes without altering the relative position of
the calcaneum to the astragalus.
Thus flexion at the medio-tarsal joint is associated with adduction and inward
rotation of the foot, occurring simultaneously with extension of the ankle; and
extension at the medio-tarsal joint is associated with abduction and outward
rotation, occurring simultaneously with flexion of the ankle.
Flexion and adduction are far more free than extension and abduction, which
latter movements are arrested by the ligaments of the sole as soon as the foot is
brought into the position in which it rests on the ground.
Although the astragalo-scaphoid is a ball-and-socket joint, and might allow
motion in any direction, yet, owing to the union of the scaphoid with the cuboid,
movement is limited by the shape of the calcaneo-cuboid joint, which, being concavo-
convex from above downwards, prevents rotation round a vertical axis, and also
any side-to-side motion except in a direction obliquely downwards and inwards,
and upwards and outwards. This is also the direction of freest movement at the
astragalo-scaphoid joint. Movement is also limited by the ligamentous union of
the calcaneum with the scaphoid. The twisting movement of the foot, such as
turning it upon its inner or outer edge, and the increase or diminution of the arch,
take place at the tarsal joints, especially the medio-tarsal and calcaneo-astragaloid
articulations. Here too those changes occur which, owing to paralysis of some
muscles or contraction of others, result in talipes equino-varus, or valgus.
6. THE TARSO-METATARSAL ARTICULATIONS
Class.-Diarthrosis.
Subdivision.-Arthrodia.
There may be said to be three articulations between the tarsus and metatarsus,
viz :--
(a) The Internal, between the inner cuneiform and first metatarsal bones.
(b) The Middle, between the three cuneiform and second and third metatarsal
bones.
(c) The Outer, or cubo-metatarsal, between the cuboid and fourth and fifth
metatarsal bones.
The arteries for the tarso-metatarsal joints are derived: (1) for the internal,
from the dorsalis pedis and internal plantar; (2) for the rest, twigs from the meta-
tarsal and deep plantar arches.
The nerve-supply comes from the anterior tibial and plantar nerves.
The movements permitted at these joints are flexion and extension of the
metatarsus on the tarsus; and at the inner and outer divisions, slight adduction and
abduction. In the outer, the lateral motion is freer than in the inner joint, and
freest between the fifth metatarsal bone and the cuboid. In the inner joint, flexion
is combined with slight abduction, and extension with adduction.
There is also a little gliding, which allows the transverse arch to be increased
or diminished in depth; the inner and two outer bones sliding downwards, and the
two middle a little upwards, when the arch is increased; and vice versa when the
arch is flattened.
(a) THE INTERNAL TARSO-METATARSAL JOINT
A complete capsular ligament unites the first metatarsal with the internal
cuneiform, the fibres of which are very thick on the under and inner aspects;
those on the outer side pass from behind forwards in the interval between the
interosseous ligaments which connect the two bones forming this joint with the
second metatarsal. The ligament on the plantar aspect is by far the strongest, and
blends at the cuneiform bone with the scapho-cuneiform ligament.

THE TARSO-METATARSAL
291
(b) THE MIDDLE TARSO-METATARSAL JOINT
Into this union there enter the three cuneiform and second and third metatarsal
bones, which are bound together by the following ligaments: dorsal, plantar, inter-
osseous.
The dorsal ligaments.-1. Some short fibres cross obliquely from the outer edge
of the internal cuneiform bone to the inner border of the base of the second meta-
tarsal bone; they take the place of a dorsal metatarsal ligament which is wanting
between the first and second metatarsal bones.
2. Between the middle cuneiform and the base of the second metatarsal bone
some fibres run directly forwards.
3. The external cuneiform is connected with (1) the outer corner of the second
metatarsal bone by a narrow band passing obliquely inwards; (2) with the third
metatarsal by fibres passing directly forwards; and (3) with the fourth metatarsal
by a short band passing obliquely outwards to the inner edge of its base.
The plantar ligaments.-A strong ligament unites the internal cuneiform and
the bases of the second and third metatarsal bones. The tibialis posticus is
inserted into these bones close beside it. Other slender ligaments connect the
middle cuneiform with the second, and the external cuneiform with the third
metatarsal bones.
The interosseous ligaments.-(1) A strong broad interosseous ligament extends
between the outer surface of the internal cuneiform, and the inner surface of the
base of the second metatarsal bone. It is attached to both bones below and in
front of the articular facets, and separates the middle from the internal tarso-
metatarsal joint. (2) A second band is attached behind to a fossa on the anterior
and outer edge of the external cuneiform and to the interosseous ligament between it
and the cuboid, and passes horizontally forwards to be attached to the whole depth
of the fourth metatarsal bone behind its internal lateral facet, and to the opposed
surfaces of the third and fourth below their lateral articular facets. It separates the
middle tarso-metatarsal, and intermetatarsal between the third and fourth bones,
from the cubo-metatarsal joint. It is more firmly connected with the third bone
than with the fourth. (3) A slender ligament composed only of a few fibres often
passes from a small tubercle on the inner and anterior edge of the external cunei-
form to a groove on the outer edge of the second metatarsal bone between the two
lateral facets.
The synovial membrane is prolonged forwards from that of the scapho-cunei-
form and intercuneiform articulations.


(c) THE CUBO-METATARSAL JOINT
The bones comprising this joint are the fourth and fifth metatarsal, and the
anterior surface of the cuboid, firmly connected on all sides by
Dorsal.
Plantar.
Interosseous ligaments.
The plantar cubo-metatarsal ligament is a broad, well-marked ligament, which
extends from the cuboid behind to the bases of the fourth and fifth metatarsal bones
in front. It is continuous along the groove at the base of the fifth metatarsal bone
with the dorsal ligament, and as it passes round the outer border of the foot it is
somewhat thickened, and may be described as the external cubo-metatarsal ligament.
On its inner side it joins the interosseous ligaments, thus completing the capsule
below. It is not a thick structure, and to see it the long plantar ligament, the
peroneus longus, and external slip of the tibialis posticus must be removed; the
attachment of these structures to the fourth and fifth metatarsal bones considerably
assists to unite them with the tarsus.
U 2

292
THE ARTICULATIONS
The dorsal cubo-metatarsal ligament is composed of fibres which pass
obliquely outwards and forwards from the cuboid to the bases of the fourth and
fifth metatarsal bones. They complete the capsule above, and are continuous
externally with the external cubo-metatarsal ligament.
The interosseous ligament shuts off the cubo-metatarsal from the middle tarso-
metatarsal joint. It is attached to the external cuneiform behind, and to the
FIG. 258. SECTION TO SHOW THE SYNOVIAL CAVITIES OF THE FOOT.
1
2
6
1. Posterior calcaneo-astragaloid.
4. Tarsal.
2. Calcaneo-cuboid.
5. Cubo-metatarsal.
5
3. Anterior calcaneo-astragalo-scaphoid.
6. First metatarso-cuneiform.
whole depth of the fourth metatarsal behind its internal lateral facet, and to the
apposed surfaces of the third and fourth bones below their articular facets. It is
continuous below with the plantar ligament.
The synovial membrane is separate from the other synovial sacs of the tarsus,
and is continued between the fourth and fifth metatarsal bones.
7. THE INTERMETATARSAL ARTICULATIONS
The bases of the metatarsal bones are firmly held in position by dorsal, plantar,
and interosseous ligaments. The first occasionally articulates by means of a distinct
facet with the second metatarsal (fig. 184).
The dorsal ligaments are broad, membranous bands passing between the four
outer toes on their dorsal aspect; but in place of one between the first and
second metatarsal bones a ligament extends from the internal cuneiform to the
base of the second metatarsal bone (page 291).
The plantar ligaments are strong, thick, well-marked ligaments which connect
the bones on their plantar aspect.
The interosseous ligaments are three in number, very strong, and are situated
at the points of union of the shaft with the bases of the bones, and fill up the
sulci on their sides. They limit the synovial cavities in front of the synovial facets.
The common synovial membrane of the tarsus extends between the second and
third, and third and fourth bones; that of the cubo-metatarsal joint extending
between the fourth and fifth.
The arterial and nerve-supply is the same as for the tarso-metatarsal joints.
The movements consist merely of gliding, so as to allow the raising or widening
of the transverse arch. Considerable flexibility and elasticity is thus given to the
anterior part of the foot, enabling it to become moulded to the irregularities of the
ground.
THE METATARSO-PHALANGEAL
293
THE UNION OF THE HEADS OF THE METATARSAL BONES
The heads of the metatarsal bones are connected on their plantar aspect by
the transverse ligament, consisting of four bands of fibres passing transversely
from bone to bone, blending with the fibro-cartilaginous or sesamoid plates of the
metatarso-phalangeal joints, and the sheaths of the flexor tendons where they are
connected with the fibro-cartilages. It differs from the corresponding ligament
in the hand by having a band from the first to the second metatarsal bone.
8. THE METATARSO-PHALANGEAL ARTICULATIONS
(a) THE METATARSO-PHALANGEAL JOINTS OF THE FOUR OUTER TOES
Class.-Diarthrosis.
Subdivision.-Ginglymus.
These joints are formed by the concave proximal ends of the first phalanges
articulating with the rounded heads of the metatarsal bones, and united by the
following ligaments:-
Two lateral.
Dorsal.
Plantar sesamoid plate.
The two lateral ligaments are strong bands passing from a ridge on each side
of the head of the metatarsal bone to the sides of the proximal end of the first
phalanx, and also to the sides of the sesamoid plate which unites the two bones
on their plantar surfaces. On the dorsal aspect they are united by the dorsal
ligament.
The dorsal ligament consists of loose fine fibres of areolo-fibrous tissue, extend-
ing between the lateral ligaments, thus completing a capsule. It is connected by
fine fibres to the under surface of the extensor tendons, which pass over and
considerably strengthen this portion of the capsule.
The plantar sesamoid plate helps to deepen the shallow facet of the phalanx
for the head of the metatarsal bone, and corresponds to the glenoid ligament of
the fingers. It is firmly connected to the lateral ligaments and the intertrans-
verse ligament, and is grooved inferiorly where the flexor tendons pass over it. It
serves to prevent dorsal dislocation of the phalanx.

(b) THE METATARSO-PHALANGEAL JOINTS OF THE GREAT TOE
The metacarpo-phalangeal joint of the great toe differs from the rest in the
following particulars:-
(1) The bones are on a larger scale, and the articular surfaces are more extensive.
(2) There are two grooves on the plantar surface of the metatarsal bone, one
on each side of the median line, for the sesamoid bones.
(3) The sesamoid bones replace the fibro-cartilaginous or sesamoid plate. They
are two small hemispherical bones developed in the tendons of the flexor brevis
hallucis, convex below, but flat above where they play in grooves on the head of
the metatarsal bone; they are united by a strong transverse ligamentous band,
which is smooth below and forms part of the channel along which the long flexor
tendon plays. They are firmly united to the base of the phalanx by strong short
fibres, but to the metatarsal bone they are joined by somewhat looser fibres.
Laterally they are connected with the lateral ligaments and the sheath of the
flexor tendons. They provide shifting leverage for the flexor brevis hallucis as
well as for the flexor longus hallucis.

294
THE ARTICULATIONS
The arteries come from the digital and interosseous branches; and the nerves
from the cutaneous digital, or from small twigs of the nerves to the interossei
muscles.
The movements permitted are: flexion, extension, abduction, adduction, and
circumduction.
Flexion is more free than extension, and is limited by the extensor tendons and
dorsal ligaments; extension is limited by the flexor tendons, the plantar fibres of the
lateral ligaments, and the sesamoid plates. The lateral motion is possible from the
shape of the bony surfaces, but is very limited, being most marked in the great toe.
It is limited by the lateral ligaments and sesamoid plates.
9. THE INTERPHALANGEAL JOINTS
Class.-Diarthrosis.
Subdivision.-Ginglymus.
The articulations between the first and second, and second and third phalanges
of the toes are similar to those of the fingers, with this important difference,
that the bones are smaller and the joints, especially between the second and third
phalanges, are often ankylosed. The ligaments which unite them are:-
Two lateral.
Dorsal.
Glenoid ligament.
The two lateral ligaments are well marked, and pass on each side of the joints
from a little rough depression on the head of the proximal, to a rough border on
the side of the base of the distal phalanx of the joint.
The dorsal ligament is thin and membranous, and extends across the joint from
one lateral ligament to the other beneath the extensor tendon, with the deep
surface of which it is connected, and by which it is strengthened.
The glenoid ligament covers in the joint on the plantar surface. It is a fibro-
cartilaginous plate, connected at the sides with the lateral ligaments, and with the
bones by short ligamentous fibres; the plantar surface is smooth, and grooved for
the flexor tendons.
The arteries and nerves are derived from the corresponding digital branches.
The only movements permitted at these joints are flexion and extension.
At the interphalangeal joint of the great toe there is very frequently a small
sesamoid bone which plays on the plantar surface of the first phalanx, in the same
way as the sesamoid bones of the metatarso-phalangeal joint play upon the plantar
surface of the head of the metatarsal bone.
Morphology of Ligaments
The various ligaments of the human body have, in very many instances, been evolved
as the result of secondary changes in muscles adjacent to joints. In a few instances
ligaments represent the degenerate remnants of cartilaginous and bony elements.
Capsular ligaments are in most joints derived from the periosteum, but they may be
strengthened by the incorporation of tendons detached from adjacent muscles.
Muscles arising from, or inserted into bones in the immediate vicinity of a joint tend
to become metamorphosed into tendon near their attachments, and a comprehensive study
of myology in low vertebrate forms indicates that there is associated with this tissue-
change a tendency for the muscle to alter its point of attachment; hence a muscle origin-
ally inserted below a joint may eventually come to have its insertion above the joint. In
the same way, a muscle arising above a joint may, as a result of altered environment,
shift its origin to some point below the joint. To this change of position the term migra-
tion of muscles has been applied. In many instances a portion of the muscle equivalent
to the distance between the original and the acquired attachment persists as a fibrous
band and fulfils the function of a ligament. This is well seen in the knee joint, where
the internal lateral ligament is derived from the adductor magnus, this muscle having
shifted its insertion from the tibia to the femur. In the same way the external lateral
MORPHOLOGY OF LIGAMENTS
295
ligament represents the tendon of the peroneus longus, which has migrated from the femur
to the head of the fibula.
One of the most remarkable examples of a tendon divorced in this way is the liga-
mentum teres in the hip joint. This curious structure was in all probability the tendon
of the pectineus, which has been detached from the muscle in consequence of the profound
alterations which have taken place in the limb during its evolution.
Among other ligaments derived in a similar way from muscles may be mentioned the
greater sacro-sciatic ligament. This was originally the tendon of origin of the biceps
femoris. The lesser sacro-sciatic is derived from the fibrous regression of portions of
the coccygeus. The sacro-coccygeal ligaments represent the muscles which lift, depress,
and wag the tail in those mammals furnished with such an appendage; indeed, these
ligaments are occasionally replaced by muscle-tissue.
The coraco-humeral ligament is derived from the original tendon of insertion of the
pectoralis minor, and not infrequently the muscle is inserted into the lesser tuberosity of
the humerus, the ligament being then replaced by the tendon of the muscle. The coraco-
clavicular, rhomboid, and gleno-humeral ligaments are probably derived from modifications
of the subclavius muscle.
The vertebral column contains several ligamentous structures of great morphological
interest. The pulpy substance in the centre of each intervertebral disc is derived from
the notochord; the suspensory ligament passing from the tip of the odontoid process
to the anterior margin of the foramen magnum is a remnant of the sheath of the noto-
chord, and indicates its position as it passed from the vertebral column into the base of the
cranium. The transverse ligament of the atlas is a persistent and functional form of the
posterior conjugal ligament uniting the rib-heads in seals and many other mammals,
whilst the interosseous ligament of the head of a rib in man is the feeble representative
of this structure in the thoracic region of the spine.
Many of the subcutaneous tracts of fascia and many aponeuroses in the human body
are derived from the metamorphosis and regression of muscle-tissue.



SECTION III.
THE MUSCLES
By J. N. C. DAVIES-COLLEY, M.A., M.C.CANTAB., F.R.C.S.
SURGEON TO AND LECTURER ON SURGERY AT GUY'S HOSPITAL; EXAMINER IN ANATOMY FOR THE CONJOINT BOARD;
LATE EXAMINER IN THE UNIVERSITY OF CAMBRIDGE
THE
THE Muscles consist chiefly of transversely striated fibres arranged in fasciculi
or bundles of various sizes; and also of white fibrous tissue, which forms the
flattened cords or sheets, the tendons and aponeuroses, as they are called, by which
most of the muscles at one or both ends are attached to the bones or cartilages
with which they are connected.
In the account of each individual muscle, it is convenient to divide the descrip-
tion into seven heads, viz.:-1. the name; 2. the shape; 3. the attachments;
4. the structure; 5. the nerve-supply; 6. the action; and 7. the relations. A short
account also of the more important variations will be added.
1. The name is given for various causes, and frequently when it consists of
more than one word, for two or even three causes, viz.: (a) the supposed action,
e.g. adductor and sartorius; (b) the shape, e.g. triangularis and lumbricalis; (c) the
direction, e.g. rectus (straight), obliquus (slanting); (d) the position, e.g. sublimis
(near the surface), profundus (far from it), gluteus (in connection with the nates);
(e) its divisions and complexity, e.g. biceps, triceps, multifidus; (f) its size, as
magnus, minimus, &c.; (g) its attachments, e.g. sterno-cleido-mastoideus.
2. The shape is sometimes difficult to define on account of the irregularity of
the outline, and curvature of the surfaces of the muscle. Some are narrow and
of a flattened cylindrical form, which may be designated ribbon-shaped. Many of
these are diminished at their extremities, and may be called fusiform or spindle-
shaped. Others are broad, and form sheets of various thicknesses, which, according
to their outline, may be described as fan-shaped, rhomboidal, triangular, or quadri-
lateral. Many, again, are compound muscles with double or multiple origins or
insertions, which are called, from this cause, bicipital, trifid, &c. This is often the
case when a strong muscle arises from many points of bone, or when a muscle
divides into many tendons below to move several small levers, such as the bones of the
fingers and toes. A few have tendons intercalated in their length, and are called
biventral or digastric muscles. It is in some cases difficult to comprehend why
certain muscles, on the one hand, which appear to be separate, are grouped under
one name as a compound muscle; and, on the other hand, muscles which might
very well be combined are distinguished by separate names. The principle of dis-
tinction appears to have been to group muscles which combine to form one belly,
and to separate those in which the tendons alone are united.
3. Of the attachments, the more fixed end of the muscle is usually called the
origin, the more movable the insertion. In enumerating the various points of


STRUCTURE OF THE MUSCLES
297
attachment, it is very necessary to bear in mind not only those to bone and
cartilage, but also those to the fibrous structures or septa and aponeuroses which
lie between or around the muscles. Such attachments are best seen when the area
of bone surface available for origin or insertion is small. By this means an
indefinite extension is given to this area, and a small bony process, such as the
inner condyle of the humerus, is able to give a firm resistance to the traction of
many strong muscles.
4. The structure will include not only the direction and curvature of the fleshy
fibres, and the extent of fibrous tissue by which these fibres arise or are inserted;
but also the internal arrangement of tendons and muscular fibre, which is often
of a somewhat complicated character. The simplest structure of all is that of
muscles with no tendons, in which the fleshy fibres run parallel from one end to
the other. Many of the small muscles of the face are of this character. The
sterno-mastoid and sartorius are examples also of muscles in which the parallel
fleshy fibres form nearly the whole of the structure. It will be found that in these
muscles, on account of the number of joints passed over and the distance of the line
of the muscle from the axes of these joints, the range of movement is very great.
In most parts of the body, however, there would be a great waste of fleshy fibre if
this arrangement prevailed. Roughly speaking, we may say, that when fleshy
fibres contract fully, their length is diminished by one half. Now, if the distance
between the movable points of the skeleton which are joined by the muscles can-
not be lessened by this amount, it is obvious that some of the contractile power
of the muscle would be wasted. When, therefore, the movable points of the
skeleton bridged by a muscle can only be approximated through a limited space,
it will be found that the parallel fleshy bundles are about twice the length of this
space, and that the rest of the muscle consists of inextensible tendon, which acts
simply as a ligament to attach the contractile muscle to the bones. But this
addition of tendon to the fleshy part of the muscle is effected in various ways. The
simplest plan is that in which the addition is made at one end or the other of the
muscle. The palmaris longus is to some extent an example of such an arrange-
ment. By examining the bones it will be seen that the front of the carpus cannot
be approximated to the internal condyle of the humerus by more than three
inches. The fleshy bundles are, therefore, of about twice this length, and they
are accumulated towards the upper end of the muscle, while the rest of its length
is occupied by a long tendon. A more common arrangement is for the short fleshy
fibres to arise in succession along the surface of a long bone or from an inter-
muscular septum, and to pass in parallel lines to the end and side of a long tendon,
which gradually thickens with the increase of the number of the fibres inserted
into it. Such a muscle is like a feather, of which the quill with its diminishing
upper extremity will represent the tendon, and the barbs upon one side of it
the fleshy fibres. Hence this arrangement is called penniform, from penna, a
feather (fig. 259). This form is found when considerable power is required, but
with only a small range of movement. To appreciate fully the effect of such a
muscle, we should in our imagination take all the short parallel fibres and place
them side by side at the end of the tendon. The muscle would then be converted
into a very thick and short fleshy mass with a very long tendon.
Frequently a muscle arises in two lines from the adjacent surfaces of two
bones, from which two sets of parallel fibres converge upon a tendon which runs
down in the interval between the bones. This arrangement resembles a feather
with barbs on either side of the quill, and is called bipenniform. Examples of both
these forms are found in the leg. The peronei arising from the fibula alone are
penniform, while the tibialis posticus and soleus, arising from both tibia and fibula,
are bipenniform.
In some cases a further complication is introduced by the origin of a muscle



298
THE MUSCLES
from both sides of several fibrous septa, as well as from the intermediate surfaces
of the bone to which the septa are attached. The insertion may also be of the same
character. A good example of this, which is called the multipenniform arrange-
ment, is the deltoid, a very powerful muscle with a short range of movement.
In some few cases the tendon is intercalated between two fleshy masses. Such
muscles are called biventral. The central tendon may represent a bony structure
found in lower Vertebrata, and the two bellies might sometimes fairly be regarded
as distinct muscles, e.g. those of the digastric muscle. In some cases the central
tendon may be of some service in preventing the pressure upon subjacent tissues
FIG. 259.-DIAGRAM SHOWING PENNIFORM MUSCLE, THE PERONEUS LONGUS; AND
BIPENNIFORM, THE TIBIALIS POSTICUS.
Peroneus longus
Tibialis posticus
which would occur if the muscle were at this point fleshy and free to thicken as it
contracted. For example, it has been suggested that the central tendon of the
omo-hyoid prevents that muscle from compressing the great vessels of the neck as
it crosses them beneath the sterno-mastoid. In one muscle, the rectus abdominis,
several of these tendinous intersections are found.
5. Nerve-supply. This is of much importance, not only from a medical and
surgical point of view, when the paralysis or spasmodic contraction of individual
muscles has to be accounted for, but also because of the light which it throws
upon the action of muscles, and the assistance which it sometimes gives us in
grouping them.
THEIR ACTION AS LEVERS
299
6. Action. Most muscles act upon the levers formed by the movable bones and
cartilages. It will be convenient, however, first to speak of those which do not act
in this manner. When a muscle passes from a fixed point like a bone to a freely
movable point such as the under surface of the skin or mucous membrane, it will
simply tend to approximate the movable point to the fixed origin. Such muscles
are found in abundance in the face, and the azygos uvulæ is a good example of one
which acts upon mucous membrane. Again, the fibres of many muscles run in
parallel curves, which combine to form a curved band or sheet. The first effect
of the contraction of such a muscle will be to straighten or flatten out the curve.
If this lies over a convex surface, as is usually the case, the action of the muscle
will be to compress the structures lying in its concavity. The buccinator and
abdominal muscles are good examples of this form of muscle. Or if the surface
upon which the curved sheet lies is concave, the muscle will tend by its contraction
to lift up the soft parts upon its deep or convex surface. As an instance of this we
have the influence of the platysma myoides upon the fascia and other structures
which overlie the great vascular channels of the neck and the apices of the lungs.
In estimating the effect of muscles acting upon the levers formed by the bones,
each of which moves upon a joint as its fulcrum, three points have to be taken
into consideration :-(1) the order of lever; (2) the distance from the fulcrum of the
points of application of the force at the insertion of the muscle, and of the resistance
to be overcome; and (3) the direction in which the force is applied. It will be
found that whereas in most levers employed in mechanics the object aimed at is
what is called mechanical advantage, i.e. by the application of a small force to
overcome a greater resistance; in the human body the object is, on the contrary,
by the exertion of a great force through a small space to overcome a small resist-
ance, but at the same time to cause motion through a much greater space, and
with a much greater speed. In the three orders of levers, the fulcrum is placed
either between the power and the resistance (first order); or at one end, with the
power at the other, and the resistance to be overcome between (second order); or at
one end with the power in the middle, and the resistance to be overcome at the other
end (third order). The power required to overcome the resistance varies inversely
with the distance of its point of application from the fulcrum. Where this distance,
or the arm of the lever as it is called, is short compared with the arm at which the
resistance acts, then the power has to be greater than the resistance, and vice versa.
In the first order of levers, if the power and resistance act parallel to one another,
there may or may not be a gain of mechanical advantage, according as the arm at
which the power acts is greater or less than the arm at which the resistance acts.
In the second order of levers there must necessarily be mechanical advantage; and
in the third order the power must be greater than the resistance, as it has to act
upon a shorter arm, so there will be what may be termed mechanical disadvantage.
In the human body there is hardly a single muscle which forms a good example
of a lever of the second order, for the simple reason that mechanical advantage is
of so much less importance than a wide range of movement with its attendant
rapidity. The best example that can be given is that of some of the muscles which
depress the mandible, e.g. the anterior belly of the digastric, which is inserted into
the extremity of the lever formed by that bone, while the resistance to be overcome
-viz. the tonic contraction of the masseter, temporal, and internal pterygoid-
is exerted at a point much nearer to the fulcrum upon which the mandible turns.
The muscles which are inserted upon the tendo Achillis are often given as an
example of this order of lever, when by their contraction they raise the heel and
lift
up
the body, the weight of which acts upon the lever of the foot through the
ankle joint. This would be a good example if another person were to lay hold of
the tendo Achillis, and by drawing upon it to raise the individual from the ground.
But the fact that the other end of the muscle springs from a part of the mass to

300
THE MUSCLES

be raised alters the conditions, and, as a matter of fact, the muscle, instead of
obtaining any mechanical advantage in its action, has to contract with a force four
or five times as great as the weight to be raised.
It will be found that most of the muscles belong either to the third order, in
which there is necessarily mechanical disadvantage, or to the first order; and in
this case the arm at which the power acts is usually the shorter, so that the power
has to be greater than the resistance. In the movements of the forearm about the
elbow as a fulcrum, the triceps acting with the very short arm afforded by the pro-
jection of the olecranon and overcoming a resistance experienced by the hand at the
other end of the radius and ulna, will be a lever of the first order. The brachio-radialis
(supinator longus) when used to flex the forearm acts at the lower end of the radius,
so as to overcome the weight of the forearm and hand, which will act through the
centre of gravity of the limb about the middle of the radius, and therefore much
nearer to the fulcrum at the elbow. If its angle of insertion were not so very
small, the muscle would thus obtain a considerable mechanical advantage. This
extreme obliquity, however, actually places the muscle in a condition of mechanical
disadvantage. Lastly, the biceps and brachialis anticus are both of them good
examples of the third order of lever, when they act by their insertion close to the
fulcrum of the elbow to flex the forearm, the centre of gravity of which is much
farther from the joint.
The direction of the tendon at its point of insertion is of great importance in
estimating the effect of the contraction of any muscle. It is rarely perpendicular to
FIG. 260.

B
K
C
D
A
R
E
its lever. There is, therefore, in nearly every case, a considerable loss of mechanical
advantage; but it should be remembered that this is more than counterbalanced
by important gains. In the first place, the range and rapidity of movement are
greatly increased for a given contraction of the muscle; and in the second place a
power is also produced by which the articular ends of the bones bridged over by the
muscle are pressed together, so that the tendency to dislocation of the joint is
diminished. A third advantage is the compactness given to the limb by the
tendons being placed in close apposition to the bones, an object which could not be
attained unless their insertions were very oblique.
Take the case of the brachio-radialis flexing the forearm. In the adjoining
diagram let E be the elbow, B E the humerus, E R the radius, and B R the line of
the brachio-radialis. To estimate how much of the contracting force of the muscle
is actually expended in flexing the forearm, all that is necessary is to take any point
K in BR, to draw K A perpendicular to E R, and form a rectangle R A K C, on R A.
If the force of the muscle acting along RB be represented by the line R K, then
RC will represent that portion of the force which tends to flex the elbow, and RA
the portion which is devoted to compression of the head of the radius against the
capitellum of the humerus, so as to strengthen the elbow joint. Again, let E R' be
the new position of the forearm after the brachio-radialis has contracted. The are
of the circle through which it has moved will be indicated by R R', a small are drawn

THEIR ACTION
301
with radius R E, and centre E. Now join R' to B, and draw another small are
RD with centre B and radius R'B. RD being the difference between B R, and
BR' will indicate the amount by which the length of the muscle has diminished
during its contraction, and R R' will represent the space through which the lower
end of the radius has moved. A comparison of the lengths of RD and R R' will
show how great has been the gain in range of movement by the oblique insertion.
of B R. If the muscle had been inserted at right angles to E R, it would, in order
to produce the same effect, have had to contract through a space equal in length to
RR'. With its oblique insertion a contraction equal in length to RD has sufficed.
The gain in range (and therefore in rapidity of movement, for by contracting through
the short distance it causes a simultaneous motion through the longer space) may
be roughly represented by the fraction RB'. In muscles in which the insertion of
the tendon is at a very small angle, the loss of power is proportionately greater, and
the gain in speed and range enormous. As instances of this may be mentioned the
insertions of the tendons of the phalanges, which produce the comparatively feeble,
but exceedingly nimble, movements of the fingers with a very small contraction of
the forearm muscles.
RD
In speaking of the direction of the muscles, it should clearly be understood that
this refers to the angle of the attachment of the tendon to the lever which has to
be moved, and not to the general direction, which is often changed by the passage

A
FIG. 261.
E
B
F
D
of the tendon or muscle over projections of bone or under arches of ligament before
it reaches its insertion.
The advantage of an oblique insertion may also be illustrated by the action of
muscular fibres, which cross one another like the two parts of the letter X in their
passage between two parallel bones; e.g. in the internal and external intercostal
muscles connecting adjacent ribs, or in the external and internal oblique muscles of
the abdomen in their passage from the crest of the ilium to the last rib. If the
muscles connecting the parallel bones ran at right angles to them, they could only
by their contraction diminish the intervening space by one-half; whereas, running
obliquely, they produce by their contraction a much greater approximation of the
bones. For let A B and C D represent two parallel bones, and EF a muscular fibre
running perpendicularly from one to the other. If its full contraction reduced the
length of the fibre by one-half, it would merely draw the point E to E'. But suppose
that two muscular fibres CE and DE converge at right angles to one another upon
the point E. The amount that they will have to contract to draw E to E' may
be readily found by describing the arc of a circle E' K or E' L about C or D as a centre,
and with CE' or DE' as a radius. EK and EL will represent the contraction
required; and it is evident that if these oblique fibres contract more strongly, they
can bring the bone A B into close apposition to CD.
When muscles pass over more than one joint, their action is somewhat more
complicated. Usually other muscles are at the same time called into play, so
302
THE MUSCLES
as to fix some of the joints, and enable the muscle to act solely upon others.
For example, when the muscles arising above the wrist are used to extend the
phalanges of the fingers, it will be found that some of the flexors of the carpus
contract so as to fix the wrist. Similarly, if the fingers are flexed in grasping an
object, it is easy to feel the tendons of the carpal extensors starting up into firm
contraction.
Occasionally the passage of a muscle over two joints is used to obtain very swift
and vigorous action. For example, if the long head of the triceps, which extends from
the axillary border of the shoulder-blade to the olecranon process, were replaced
by an inextensible ligament, which should be tight with the arm down and the
elbow flexed, the elevation of the humerus by the deltoid muscle would necessitate
a corresponding extension of the elbow. Now put in the place of the inextensible
ligament an actively contracting muscle, and it is clear that the combination of this
elevation of the arm by the deltoid with contraction of the triceps will produce a
much more rapid extension of the elbow, such as is seen in throwing a spear or a
stone.
MUSCLES OF THE UPPER EXTREMITY
The first group consists of those which, arising from various parts of the head,
neck, and trunk, are inserted into the bones of the shoulder girdle, viz. the clavicle
and scapula, or into the humerus. Of this group there are two divisions: the one
comprising the muscles which take their origin from the back of the head, neck,
and trunk; the other, those which arise from the front and sides of the thorax.
POSTERIOR DIVISION OF THE GROUP OF MUSCLES PASS-
ING FROM THE TRUNK TO THE
TRUNK TO THE UPPER EXTREMITY.

This division consists of two layers, which lie superficial to the proper back
muscles. Overlying these layers is, firstly, the superficial fascia, which is strong
and well provided with fat, and is continuous with that of the head, neck, axilla,
and other adjacent regions; and, secondly, the deep fascia, which is thin and forms
the sheath of the trapezius and latissimus dorsi muscles. Above and in front, the
deep fascia is continuous with the deep cervical fascia; lower down, with the axillary
fascia, and that covering the thoracic and abdominal parietes. Internally it is attached
to the spines of the vertebræ, and below it blends with the lumbar aponeurosis.
FIRST LAYER
Consisting of one muscle-the trapezius.

THE TRAPEZIUS
The trapezius (or cucullaris, as it has been called from its resemblance to a
cowl =
cucullus) is named from Tpárea, a table, on account of the four-sided
figure formed by the muscles of the two sides. It is a fan-shaped sheet forming
an obtuse-angled triangle, the long side of which corresponds with the spine.
Origin. (1) The inner third of the superior nuchal line of the occipital bone,
FIG 262.-FIRST LAYER OF MUSCLES OF THE BACK.

Triceps
Sterno-mastoid
Deltoid-
Trapezius
Teres minor
Infraspinatus
Teres major
Rhomboideus major
Pectoralis major
Serratus magnus
Latissimus dorsi
Obliquus externus
Gluteus medius
Gluteus maximus

304
THE MUSCLES
and the external occipital protuberance; (2) the posterior border of the ligamentum
nucha; (3) the spines of the seventh cervical and all the thoracic vertebræ, together
with the supraspinous ligaments.
Insertion. (1) The posterior border of the outer third of the clavicle and the
adjacent part of its upper surface; (2) the inner edge of the upper surface of the
acromion process; (3) the upper border of the spine of the scapula, and a small
tubercle at its inner extremity.
Structure. The origin of the muscle is by short tendinous intermingled with
fleshy fibres, except at two places, where the tendinous fibres form a continuous
sheet. The first of these is from the middle of the ligamentum nucha to the second
thoracic spine; here a conspicuous oval aponeurosis is formed by the tendons of the
two sides. The second is at the lower acute angle of the muscle where it arises
from the lowest thoracic vertebra. The muscular fibres converge from the extensive
origin, and just before their insertion the sheet of the muscle is folded upon itself,
to adapt it to the V-shaped process of the shoulder girdle, into which it is inserted
by fleshy fibres, except at the inner extremity of the spine of the scapula, where
a tendinous sheet plays over the triangular base of that process, before it is inserted
into the tubercle at the inner end of the spine. Sometimes a bursa intervenes
between this sheet and the triangular surface of the scapular spine.
Nerve-supply. From the spinal accessory; and from the deep cervical plexus
by branches of the third and fourth cervical nerves, which, after communicating
with the spinal accessory, enter with it the deep surface of the muscle a short
distance above the clavicle..
Action. Its upper fibres draw upwards the outer end of the clavicle and the
point of the shoulder; and acting from below, they extend the head, flex the neck
to the same side, and turn the face to the opposite side. Its middle fibres draw
the scapula inwards towards the spine; at the same time they produce a rotation
of the scapula on the thorax, by which the point of the shoulder is raised. The
lower fibres draw the scapula downwards and inwards, and at the same time rotate
it so as to raise the point of the shoulder.
Acting as a whole, the muscle draws the scapula towards the middle line of
the back, and elevates the shoulder by the rotation it impresses upon the shoulder-
blade. By drawing the scapula backwards, it gives some help to the pectoralis
minor and other muscles which elevate the ribs in forced inspiration. When it
takes its fixed point from the shoulder-blade and clavicle, as when the hand grasps
firmly some immovable object, the muscle will draw the spines of the vertebræ
towards the scapula.
The presence of the oval aponeurotic patch may be explained by the fact that
the range of movement of the scapula in a horizontal direction backwards and
inwards is more limited than when the inward movement is combined with an
upward or downward direction. This limitation is due to the ligamentous attach-
ments of the clavicle and shoulder blade.
-
Relations. Superficially, the integuments and subcutaneous nerves; deeply, the
complexus splenii, serratus posticus superior, rhomboidei, the vertebral aponeurosis
covering the continuations upwards of the erector spinæ, the external intercostals,
latissimus dorsi, levator anguli scapulæ, omo-hyoid, scalenus medius and posticus,
the supraspinatus, and a small portion of the infraspinatus.
Variations.--Occasionally the upper or the lower part of its origin may fail. The
clavicular part of its insertion sometimes extends far forwards upon the clavicle. Fre-
quently fibres pass from its anterior border to the inner end of the clavicle either in front of
or behind the sterno-mastoid, forming an arch under which run some of the superficial
nerves. This arch may even extend to the sternum. A similar transverse band is occasion-
ally found in the upper part of the posterior triangle, the transversus nucha. Sometimes
a longitudinal band of fibres covers the spinal origin of the trapezius.
LEVATOR ANGULI SCAPULE-RHOMBOIDEI
305
SECOND LAYER
Consists of four muscles-the levator anguli scapulæ, rhomboideus minor and
major; and the latissimus dorsi.
1. LEVATOR ANGULI SCAPULE
The levator anguli scapulæ (figs. 263 and 266), named from its action in raising
the posterior superior angle of the scapula, is a ribbon-shaped muscle.
Origin. By four short tendons from the posterior tubercles of the transverse
processes of the four upper cervical vertebræ.
Insertion. The vertebral border of the scapula opposite the supraspinous
fossa.
Structure. The tendons of origin, which are closely connected with the inser-
tion of the splenius colli, after a short course are succeeded by muscular bellies,
and these unite to form a thick band of parallel fibres which remain fleshy to their
insertion. The plane of the muscle changes as it descends. Above, while lying in
the posterior triangle of the neck, its surfaces look outwards and inwards; below,
they are directed backwards and forwards.

Nerve-supply.
From the cervical plexus by branches from the third and
fourth cervical nerve which enter the front of the outer surface near the origin of
the muscle.
Action. It raises the posterior superior angle of the scapula; but, by causing
rotation of that bone, it depresses the point of the shoulder. Taking its fixed
point from below, it is an extensor and lateral flexor of the neck.
Relations. Superficially, the deep cervical fascia, the platysma myoides, the
sterno-mastoid, the trapezius, the scalenus medius, the internal jugular vein, the
spinal accessory nerve, and some of the descending branches of the cervical plexus;
deeply, the splenius colli, the cervicalis ascendens, the serratus posticus superior,
and the posterior scapular vessels.
Variations. The number of cervical vertebræ from which the muscle arises varies, and
it may even arise from the mastoid process or occipital bone. It may send slips to the
serratus magnus, the serratus posticus major, and other adjacent muscles; occasionally
also to the clavicle and first two ribs.

2 AND 3. RHOMBOIDEI
The rhomboidei-named from their shape, which is rhomboidal, or like a
parallelogram-are sometimes looked upon as a single muscle, but may be
usually separated into the following:-
The rhomboideus minor, the lesser and upper of the two, is a four-sided sheet,
forming an elongated parallelogram.
Origin. The lower part of the ligamentum nuchæ, the spines of the seventh
cervical and first thoracic vertebræ, and the supraspinous ligament between them.
Insertion. The vertebral border of the scapula opposite its spine.
Structure. Its origin and insertion are by short tendinous fibres, between
which its fleshy fibres run parallel to one another, downwards and outwards.
Nerve-supply. From the brachial plexus by a branch of the fifth cervical
nerve, which enters its deep aspect near the upper border a short distance above its
insertion.
For action and relations, see the account of the following muscle.

X
306
THE MUSCLES
The rhomboideus major-the lower and larger of the two muscles-is a broad
rhomboidal sheet.
Origin. The spines of the four or five upper thoracic vertebræ, and the supra-
spinous ligaments between them.
FIG. 263.-THE LEVATOR ANGULI SCAPULE AND RHOMBOIDEI.

24
Supraspinatus
Infraspinatus-
Teres major.
Serratus magnus
Serratus posticus
inferior
Obliquus internus
eda
gamor
Complexus
Splenius capitis
Levator anguli scapulæ
Serratus posticus superior
Rhomboideus minor
Splenius colli
Rhomboideus major
RHOMBOIDEI-LATISSIMUS DORSI
307
Insertion. The vertebral border of the scapula opposite the infraspinous fossa.
Structure. At the origin, of short tendinous fibres, succeeded by parallel fleshy
bundles, which pass downwards and outwards to a narrow tendinous expansion
which is feebly attached to the scapula over the upper three-fourths of its insertion,
but with thick and strong fibres near the inferior angle of that bone.
Nerve-supply.-The same as the preceding, and entering the upper part of the
deep surface near its insertion.
Action. The rhomboidei draw the scapula inwards and backwards towards
the middle line, and at the same time upwards. They also rotate the scapula so
as to depress the point of the shoulder. In this way they, together with the levator
anguli scapulæ, will help in drawing down the arm, after it has been elevated
through the rotation of the scapula by the trapezius and serratus magnus.
Acting from the scapula, the rhomboidei will help the trapezius in drawing the
middle line of the back towards that bone.
Relations of the two rhomboidei.--Superficially, the trapezius and, at the lower
part of the rhomboideus major, the deep fascia, and latissimus dorsi; deeply, the
serratus posticus superior, splenius colli, the vertebral aponeurosis covering the
upper continuations of the erector spinæ, the external intercostals, and the posterior
scapular vessels.
Variations. The rhomboideus minor is frequently absent, and occasionally there is no
rhomboideus major. The fibres of the latter muscle may be inserted almost entirely into
the lower angle of the scapula. Occasionally its lower fibres join those of the latissimus
dorsi, and they have also been found continuous with a part of the teres major. An
accessory band may join the rhomboidei from the occipital bone (the occipito-scapularis).
4. LATISSIMUS DORSI
The latissimus dorsi (figs. 262, 269)-named from its being the broadest of the
back muscles-is a fan-shaped sheet forming a right-angled triangle, the right angle
being contained between its upper and vertebral borders.
Origin. (1) The five or six lower thoracic spines, and the supraspinous liga-
ments; (2) the lower part of the vertebral aponeurosis (see account of LUMBAR
FASCIA, page 434), by which it is attached to the spines of all the lumbar and
sacral vertebræ; (3) the posterior third of the outer lip of the crest of the ilium;
(4) horizontal lines crossing the outer surface of the last three or four ribs external
to their angles (these lines by their lower borders give origin to processes of the
external oblique muscle, which thus interdigitates with the latissimus dorsi); (5) the
dorsal aspect of the inferior angle of the scapula.
Insertion. The bottom of the bicipital groove of the humerus, as far upwards
as the lesser tuberosity.
Structure. Its first and third parts arise by short tendinous fibres. The origin
of the second part from the vertebral aponeurosis is by fleshy fibres in a line which
descends obliquely downwards and outwards from the last thoracic spine to the
back of the crest of the ilium. Its origin from the ribs and scapula is muscular.
The fleshy fibres are of nearly equal length, and they converge upon the tendon in
such a way that those which arise from the ribs and crista ilii are inserted highest
into the humerus, while those which spring from the thoracic spine are attached
to the lower part of the bicipital groove. The broad sheet wraps round the side
of the thorax, and is also folded upon itself, so that the anterior surface at the
origin becomes the posterior at the insertion. A groove is thus formed, in which
lie the outer border of the scapula and the teres major. The tendon of the teres
major is usually attached at the borders to that of the latissimus dorsi by strong
connective tissue; but a bursa intervenes between them near their insertion.

x 2
308
THE MUSCLES

Nerve-supply. From the posterior cord of the brachial plexus by means of the
long subscapular nerve. This is derived from the fifth cervical nerve, and enters
the muscle upon its deep surface in the lower part of the axilla.
Action. It draws the humerus backwards, downwards, and inwards; at the
same time rotating it inwards. The movement of the arm in swimming is a good
example of its action. When the arm is placed close to the side, it will draw the
shoulder backwards and downwards.
Acting from the humerus as a fixed point, it is very important in climbing, as it
draws the pelvis and lower part of the trunk upwards and forwards towards the
arms.
-
By its costal origin it will assist in forced inspiration when the arm is fixed.
Relations. Superficially, the trapezius, fasciæ, and integument, the pectoralis
major, axillary vessels, and branches of the brachial plexus; deeply, the rhomboi-
deus major, the vertebral aponeurosis, covering the upward continuations of the
erector spinæ muscle, the serratus posticus inferior, external intercostals, external
oblique, infraspinatus, serratus magnus, and teres major muscles.
Variations. It varies in the height of its origin from the spinal column, and also in
the number of ribs from which it arises. From its axillary border slips may cross the
axilla to the tendon of the pectoralis major, or may cross the great vessels and nerves to
the coracoid process or the deep fascia at the upper part of the arm. A slip of fascia or
muscle may be continued down from its tendon of insertion to the olecranon in association.
with the triceps.
OF
TRUNK TO
THE
MUSCLES
UPPER
DIVISION OF THE GROUP
FROM THE
ANTERIOR
PASSING
EXTREMITY
These muscles are arranged in three layers, of which the first two are formed
by muscles which arise from the front of the thorax: viz., the pectoralis major in
the first layer, and the subclavius and pectoralis minor in the second; the last by
a single muscle, the serratus magnus, which takes origin from the side of the
thorax.
The superficial fascia, which covers all these sheets, is but moderately supplied
with fat, and is continuous with that of all the adjacent regions. It lies both over
and beneath the mammary gland, and sends fibrous septa between its lobules.
In addition to the superficial fascia, there are three other important fasciæ in
this region.
1. The pectoral fascia, a thin membrane which forms the sheath of the pectoralis
major, and is attached to the clavicle above; while below it passes over the free edge
of the great pectoral muscle, and there unites with the axillary fascia.
2. The clavi-pectoral fascia arises in two sheets from the anterior and posterior
borders of the under surface of the clavicle. These sheets unite after enclosing
the subclavius muscle, and form a single membrane which is much thicker at its
outer and upper part, where it is attached to the coracoid process and blends with
the front of the sheath of the axillary vessels. It bridges over the interval
between the subclavius muscle and the pectoralis minor, and is here called the
costo-coracoid membrane. This membrane is of a quadrilateral shape, attached
above and below to the sheaths of the subclavius and the pectoralis minor muscles,
externally to the upper surface of the coracoid process, and internally it becomes
very thin and blends with the fascia covering the two upper intercostal spaces.
Below, the clavi-pectoral fascia becomes thin, and forms the sheath of the pectoralis
minor. At the lower border of this muscle it joins the axillary fascia.
3. The axillary fascia is a strong membrane which stretches across the triangular




PECTORALIS MAJOR
309
floor of the axilla. In front, it joins the pectoral and clavi-pectoral fasciæ; behind,
it joins the sheath of the latissimus dorsi; above, it is continuous with the deep
fascia of the upper arm, and below with that of the thorax.
The concavity of its surface, which is directed downwards and outwards, is
maintained to a great extent by the attachment of the clavi-pectoral fascia above
mentioned.
FIRST LAYER

PECTORALIS MAJOR
The pectoralis major-named from its being the larger of the two muscles which
arise from the front of the chest (pectus breast)-is a thick, triangular, fan-shaped
sheet; or, more accurately, it may be likened to the sector of a circle on account of
the curved origin, from which all the fibres converge to the upper part of the
humerus as a centre.
FIG. 264.--THE PECTORALIS MAJOR AND DELTOID.

Sterno-
mastoid
Deltoid
Biceps
Teres major
-Pectoralis major
- Latissimus dorsi
Serratus magnus
Aponeurosis of external oblique
External intercostal
Origin. (1) The anterior surface of the inner half of the clavicle and the
adjacent part of the sterno-clavicular joint; (2) the side of the front of the
sternum, from the sterno-clavicular joint to the lower extremity of the gladiolus;
(3) the front of the cartilages of the second to the sixth ribs; (4) a small part of
the outer surface of the sixth rib close to its anterior extremity; (5) the upper
310
THE MUSCLES
part of the aponeurosis of the external oblique muscle which forms the front of
the sheath of the rectus abdominis.
Insertion. (1) The external bicipital ridge of the humerus from the greater
tuberosity down to the impression for the deltoid; (2) adjacent fibrous structures,
especially the tendon of insertion of the deltoid muscle.
Structure. The clavicular portion is distinct from the rest, and might be
described as a separate muscle. It forms a thick band of parallel fibres, which,
arising tendinous from the clavicle, become almost immediately fleshy, and are
inserted into the humerus by short tendinous fibres in front of the rest of the
tendon of insertion.
The rest of the muscle (the sterno-costal portion as it is usually named) consists
of fleshy fibres which, arising directly from the four points of origin already
enumerated, converge and cross one another to be inserted into the humerus behind
the clavicular portion by means of a peculiar tendon.
In a vertical section (fig. 271) near the humerus this tendon is seen to be folded
upon itself into a compressed horseshoe-shape. The convexity of the folded tendon
is directed downwards, and the anterior segment of the horseshoe is shorter than
the posterior.
The anterior segment receives the muscular fibres which proceed from that
part of the origin of the sterno-costal portion which lies above the third costal
cartilage, and with the front of this segment the insertion of the clavicular portion
is closely blended. The posterior segment receives the fibres from the lower part
of the sterno-costal portion, the lowest fibres (viz. those from the external oblique
aponeurosis) being inserted highest, and the highest (viz. those from the middle of
the sternum) being attached to the lower part of the horseshoe, where they become
continuous with those forming the anterior segment of the tendon.
In consequence of this arrangement the lower fibres of the muscle disappear
from view soon after their origin, and are concealed by the clavicular and upper
sterno-costal fibres. This arrangement gives to the anterior border of the axilla
a concave outline. Were it not for this decussation, the muscle would be broader
and thinner, and would cause an inconvenient and unsightly projection in front of the
axilla.
The sterno-costal portion may usually be divided into a superficial and deep
plane, the superficial being composed of the sternal and external oblique origin; the
deep, of the fibres which spring from the ribs and their cartilages.
Nerve-supply. From all the nerves of the brachial plexus :-(1) through the
external anterior thoracic nerve, which enters the deep surface of the muscle just
below the middle of its upper border; and (2) through the internal anterior
thoracic, which, after piercing and supplying the pectoralis minor, enters the deep
surface of the muscle an inch lower down, half-way between its origin and
insertion.
Action.-To adduct, flex, and rotate inwards the upper arm. By its clavicular
portion it will draw the arm more directly forwards, as in round-hand bowling,
while the sterno-costal portion will draw the arm more downwards than forwards.
The whole muscle will be used with great force in striking a blow downwards and
forwards. When the arm hangs close to the side, the pectoralis major will draw
the scapula forwards and downwards, so as to advance and depress the point of
the shoulder, as may be seen in a person shivering with cold. When the arm is
elevated and fixed, this muscle will draw the front of the chest up to it, as in
climbing. It will also raise the upper ribs in forced inspiration.
Relations. Superficially, the platysma myoides, the mammary gland, and the
cutaneous nerves from the descending branches of the cervical plexus, as well as
the lateral and anterior perforating branches of the upper intercostals.
Beneath, lie the subclavius, pectoralis minor, and serratus magnus, the fascia

PECTORALIS MAJOR-SUBCLAVIUS
311
covering the external and internal intercostal muscles, the coracoid process, and
costo-coracoid membrane, with the structures which pass through the membrane,
viz. the cephalic vein, acromio-thoracic vessels, and the external anterior thoracic
nerve. Further outwards it forms part of the anterior wall of the axilla, and enters
into relation with the axillary vessels and nerves.
The upper border is separated from the deltoid by the cephalic vein and the
humeral branch of the acromio-thoracic artery.
Variations. The clavicular and sterno-costal portions are often widely separated.
They may also be further subdivided into separate bands or sheets, and they may be
wholly or partly absent. Occasionally, the muscles of the two sides join across the
sternum, or muscular bands may join the sternal ends of the clavicle. Bands may cross
from the axillary border to the latissimus dorsi or the deep fascia of the upper arm;
deeper bands may also pass to the insertion of the pectoralis minor, or the capsule of the
shoulder joint.
SECOND LAYER
1. SUBCLAVIUS
The subclavius-named from its position beneath the clavicle (=clavis)-is
almost cylindrical, but may be more accurately described as a thick sheet of the
shape of a low obtuse-angled triangle, the obtuse angle being contained between the
clavicular attachment and the inner free border of the muscle.

FIG. 265.-THE SUBCLAVIUS AND THE UPPER PORTION OF THE SERRATUS MAGNUS.
Subclavius
Serratus magnus
Origin. The upper and anterior surface of the first rib and its cartilage at
their point of junction.
Insertion. The groove on the lower surface of the clavicle from the rhomboid
impression to the conoid tubercle.
Structure. It arises by a strong tendon, flattened from before backwards,
which lies close to the front of the rhomboid ligament, and is continued for a con-
siderable distance along the lower border of the muscle. Its insertion is by fleshy
fibres which radiate upwards, outwards, and a little backwards, in a penniform
manner, from this tendon; the inner ascending more vertically, and the outer
very obliquely.
Nerve-supply. From the brachial plexus by a small branch which, arising
from the fifth and sixth cervical nerves, passes behind the clavicle and enters the
middle of the back of the muscle.
Action.-To draw the outer end of the clavicle, and with it the point of the
shoulder, downwards and slightly forwards; but chiefly by pulling the bone inwards

312
THE MUSCLES
to supplement the ligaments which prevent dislocation of the sterno-clavicular
joint.
Relations. In front, the clavi-pectoral fascia and the pectoralis major; behind,
FIG. 266. THE PECTORALIS MINOR, OBLIQUUS INTERNUS, PYRAMIDALIS, AND
RECTUS ABDOMINIS.
Levator anguli scapulæ
Biceps
Pectoralis
major
Teres major
Subscapularis
Pectoralis minor
Latissimus dorsi
Serratus magnus
Internal oblique
Rectus
Pyramidalis
Conjoined tendon


PECTORALIS MINOR-SERRATUS MAGNUS
313
the posterior division of the same fascia, the rhomboid ligament, the subclavian
vessels, and the brachial plexus.
Variations.-The subclavius may be absent, or its insertion may extend to the coracoid
process, transverse ligament, and upper border of the scapula. Occasionally the costo-
clavicular portion is separate from the costo-scapular. Again, its origin may extend
inwards to the sternum, and the portion which arises from the sternum may be separate
from the rest of the muscle.
2. PECTORALIS MINOR
The pectoralis minor-named from its being the smaller of the two muscles
which arise from the front of the chest-is a fan-shaped or triangular sheet, with its
inner edge divided into three teeth.
Origin. (1) The upper borders and outer surfaces of the third, fourth, and fifth
ribs near their anterior extremities; (2) the fascia covering the intercostal muscles
in the spaces between these ribs.
Insertion. (1) The upper surface of the coracoid process of the scapula;
(2) the upper part of the tendon of the coraco-brachialis along its inner border.
Structure. Its origin is by aponeurotic slips, which, after becoming fleshy,
converge upwards, outwards, and somewhat backwards, upon the flattened tendon,
which is attached chiefly to the coracoid process, but blends for an inch or more
below that process with the origin of the coraco-brachialis.
Nerve-supply. From the inner cord of the brachial plexus (through the
eighth cervical nerve) by the internal anterior thoracic, which enters its deep surface
near the upper border, the nerve subsequently piercing the muscle to send filaments
to the pectoralis major.
Its action is to draw downwards and forwards the scapula, depressing at the
same time the point of the shoulder. Taking its fixed point from the coracoid
process, it draws upwards and outwards the ribs to which it is attached, and
so helps in forced inspiration. Its connection with the tendon of the coraco-
brachialis will enable it to act slightly as a flexor and adductor of the humerus.
Relations. Superficially, the pectoralis major; deeply, the external intercostal
muscles; and, near its insertion, the axillary vessels and brachial nerves.
Variations. The origin may extend upwards as far as the second, or downwards to
the sixth rib, and it may receive additions from the pectoralis major. It is occasionally
altogether absent. Its insertion may be continued over the coracoid process to the
capsule of the shoulder joint, the greater tuberosity of the humerus, or the clavicle.

THIRD LAYER
SERRATUS MAGNUS
The serratus magnus-named from its serrated or saw-like anterior border and
large size-is an irregular quadrilateral sheet curved to the shape of the side of the
thorax. Its anterior attached border has a somewhat sinuous curve, and arises from
the side of the thorax by nine or ten digitations or teeth, which, by their saw-like
appearance, give the muscle its name. The muscle may be divided into an upper,
middle, and lower part.
Origin. First part, by two teeth from the middle of the outer surface of the
first and second ribs, and from the fascia covering the first intercostal space.
Second part, by two or three heads from the second, third, and sometimes the
fourth ribs upon their outer surface. Third part, by far the largest and strongest
portion of the muscle, arises from the fourth or fifth to the eighth or ninth ribs by
a series of teeth, which are attached in front near the upper border of each rib, and
314
THE MUSCLES
behind to a line running backwards across the outer surface of the rib from its
upper to its lower border. These attachments form a curved line with the convexity
forwards, the attachment to the sixth rib being the most anterior and prominent.
Insertion. The first part is attached to an oval space upon the venter of the
scapula close to the posterior superior angle. The second part, to the whole of
the vertebral border of the scapula upon its ventral aspect. The third part to
the large oval space on the venter of the scapula close to its inferior angle.
Structure. The origin of the muscle is by fleshy or short aponeurotic fibres,
FIG. 267.-SERRATUS MAGNUS.

Upper part of
serratus magnus
Middle part-
Lower part-
and in the first part these fibres converge very slightly towards their fleshy insertion.
In the second part they diverge and form a thin sheet attached to the vertebral
border of the scapula. In the third part of the muscle the fibres converge fanwise
and form a very thick and strong fleshy mass which is inserted directly into the
inferior angle of the scapula. At their origin the teeth of this part of the muscle
interdigitate, that is, meet and fit in between, those of the origin of the obliquus
abdominis externus. All the fibres are curved to fit on the convex wall of the
chest.
Nerve-supply. From the brachial plexus by the posterior thoracic nerve, which
is derived from the fifth, sixth, and seventh cervical nerves. After running down
the side of the chest upon the outer surface of the muscle, the nerve is distributed
by many branches to the various digitations.
Action.-By its contraction this muscle draws forwards the vertebral border of
the scapula and, as the third part of it is much the strongest, it will act especially
upon the inferior angle, and will rotate the scapula so as to raise the point of the

SERRATUS MAGNUS
315
shoulder. It will therefore help the trapezius muscle in lifting up the shoulder,
and it will be brought powerfully into play whenever the shoulder is used in pushing
in a forward direction. It is most important, however, in relation to the movements
of the arm. In order that the deltoid muscle may raise the humerus, it is necessary
that the fulcrum formed by the glenoid portion of the scapula should be held steady.
For this reason the scapula extends so far downwards in order that the leverage
given to the third and most powerful portion of the serratus may be as great as
possible. When the serratus magnus is paralysed, all the efforts of the deltoid to
elevate the arm are unsuccessful, and only cause the lower angle of the scapula to
project from the back of the thorax. When the arm has been elevated to its full
extent by the deltoid, that is, through about a right angle, the rotation of the scapula
due to the serratus magnus and trapezius will produce a further elevation through
another right angle, and so place the arm in a vertical position. One of the results
of the action of this muscle is to keep the lower angle of the scapula in close contact
with the wall of the thorax. When the muscle is paralysed, the posterior borders
and the inferior angles of the scapulæ project backwards from the thorax like
small wings (scapula alata).
Acting from its scapular insertion, the muscle tends to draw the front of the
chest towards the scapula, e.g. where it supports the thorax in crawling on the
hands and knees. Judging from the direction in which its fibres are inserted
into the ribs, most of them can have little if any action in elevating the ribs, as in
forced inspiration.
Relations. Superficially, the pectoralis major and minor, the subscapularis and
latissimus dorsi, the subclavian and axillary vessels and the brachial plexus; deeply,
the external intercostal muscles, and serratus posticus superior.
Variations. It may arise as low as the tenth rib; and above, it may receive slips from
the cervical transverse processes, or the levator anguli scapula. Part or the whole of the
muscle may be deficient.
The second group comprises the muscles which pass from the scapula to the
upper limb, and move the upper arm. Some of the most important adductors,
flexors, and extensors belong to the first group; but abduction and rotation in both
directions are provided for by the second group.

MUSCLES WHICH PASS FROM THE SCAPULA TO THE
UPPER LIMB
These are nine in number, viz. the deltoid, supra-spinatus, infra-spinatus, teres
minor, subscapularis, teres major, coraco-brachialis, biceps, and triceps. The two
last, however, as they act chiefly upon the forearm, will not be described in this
group.
The superficial fascia covering the muscles contains but little fat. The deep
fascia is thin where it covers the front of the deltoid, and is continuous with that
which invests the pectoralis major. Behind, it is thicker, especially where it covers
in the lower part of the infra-spinatus. Below, it blends with the deep fascia of
upper arm. Above, it is connected with the long prominences of the clavicle
and scapula at the upper border of the deltoid.
the
It is also connected, either directly or by strong intermuscular septa, with the
vertebral and axillary borders of the scapula.
Processes from it cover the deeper surface of the deltoid, and form sheaths to
all the muscles of this group.
316
THE MUSCLES
1. DELTOID
The deltoid muscle (figs. 262, 264)-named from its resemblance to the Greek
letter delta when inverted-is a very thick triangular sheet, with the apex
directed downwards, and with its plane curved upon itself from before backwards,
so as to wrap round the front, outer side, and back of the upper end of the
humerus.
Origin. (1) The anterior border and adjacent part of the upper surface of the
outer third of the clavicle; (2) the outer border and adjacent part of the upper
surface of the acromion; (3) the lower border of the spine of the scapula and
the fascia covering the infra-spinatus muscle, near the vertebral border of the
scapula.
Insertion.-A rough triangular impression, with the apex downwards, and from
two to three inches long, just above the middle of the outer surface of the
humerus.
Structure. At the front and back part of its origin it arises by short, tendinous
fibres which end in parallel muscular bundles. At the middle part, strong fibrous
septa three or four in number pass downwards from the acromion process into the
substance of the muscle, upon the surface of which their outer edges are visible.
The fleshy fibres of this part of the muscle arise both from the acromion and from
the surfaces of these septa. The short strong tendon of insertion is prolonged
upwards into three fibrous planes, which, as well as the tendon, receive the
fleshy fibres of the middle part in multipenniform fashion. The muscular
bundles from the front and back parts of the origin are inserted upon the
anterior and posterior surfaces of the tendon of insertion. In front, this tendon
is connected with that of the pectoralis major; below, it gives fibres to the
external intermuscular septum, and also to the upper part of the brachialis
anticus.
Nerve-supply. From the posterior cord of the brachial plexus (through the
fifth and sixth cervical nerves) by means of the circumflex nerve. This nerve
enters the deep surface of the muscle by several filaments about half way between
the origin and insertion.
Action. When all its fibres contract together, it will abduct the humerus
through a right angle. If the first and second parts act alone, they will flex and
abduct the arm, as when it is raised to the level of the shoulder and at the same
time directed forwards. The posterior and middle portions of the muscle by their
contraction will abduct the arm, and at the same time extend it, as when the arm
is elevated, and at the same time directed backwards.
The movements of abduction, or of abduction combined with flexion, are
through 90°; of abduction combined with extension, only through 45°. In its action
the muscle forms a lever of the third order. The greater advantage which it
gains by its insertion at a considerable distance from its fulcrum at the shoulder
joint is lost by the extreme obliquity of its direction. Hence the great thickness
and strength of the muscle, and the facility with which this movement is lost
by injury or disease. For the proper action of this muscle in elevation of the
arm, it is necessary for the scapula to be held firm by means of the serratus

magnus.
Relations. Superficially, the integument and deep fascia; upon its front border,
the pectoralis major, a small artery, and the cephalic vein; deeply, the coracoid
process and upper extremity of the humerus, the tendons of the pectoralis minor
and major, the short head of the biceps, coraco-brachialis, subscapularis, supra-
spinatus, infra-spinatus, teres minor, the long heads of the biceps and triceps, the
outer head of the triceps, the coraco-clavicular and coraco-acromial ligaments, the
DELTOID-SUPRA-SPINATUS-INFRA-SPINATUS
317
circumflex arteries and nerve, and a large bursa which separates the muscle from
the greater tuberosity of the humerus and the structures attached to it; below, it
comes into contact with the upper part of the brachialis anticus.
Variations. The clavicular portion of its origin may reach inwards as far as that of
the pectoralis major, and the two muscles may blend along their adjacent borders. Behind,
it may receive separate bands from the fascia infra-spinata or the borders of the scapula.
Occasionally transverse fibres have been found lying in the substance of the muscle close
to its acromial origin.
2. SUPRA-SPINATUS

The supra-spinatus-named from its position above the spine of the scapula-
is a somewhat fan-shaped, thick triangular sheet.
-
Origin. (1) The inner two-thirds of the supraspinous fossa; (2) the upper
surface of the spine of the scapula; and (3) the fascia covering the muscle.
-
Insertion. (1) The upper facet of the greater tuberosity of the humerus; and
(2) the capsular ligament of the shoulder joint.
Structure. It arises by fleshy fibres which converge upon a tendon which is
concealed in the substance of the muscle almost to the point of its insertion.
Nerve-supply. From the brachial plexus (through the fifth cervical nerve) by
the suprascapular branch which enters the muscle upon its deep aspect near its upper
border.
Action. It assists the deltoid in abducting the arm; it also strengthens the
shoulder joint by resisting the tendency to upward displacement of the head of the
humerus, and by drawing the head of the humerus firmly towards the centre of the
glenoid cavity.
Relations. Superficially, the trapezius, deltoid, and coraco-acromial ligament;
deeply, the omo-hyoid muscle and capsular ligament, the suprascapular vessels and

nerve.
Variations. It occasionally receives part of the tendon of the pectoralis minor.
3. INFRA-SPINATUS
The infra-spinatus-named from its position below the spine of the scapula-
is a fan-shaped, thick, triangular sheet.
Origin. (1) The inner two-thirds of the infraspinous fossa; (2) the under
surface of the spine of the scapula; (3) the infraspinous fascia, and a thick inter-
muscular septum which separates it from the teres minor and major muscles.
Insertion. (1) The middle facet on the greater tuberosity of the humerus; and
(2) the capsule of the shoulder joint.
Structure. Its origin is by fleshy fibres which converge outwards in bipenni-
form fashion upon the tendon. Frequently that part which arises from the lower
surface of the spine of the scapula overlies and is somewhat separate from the rest.
Its insertion into the capsule and tuberosity is by a tendon which is almost entirely
concealed by fleshy fibres.
Nerve-supply. From the brachial plexus (through the fifth cervical nerve), by
the suprascapular branch which enters the deep surface of the muscle at its outer
part and near its upper border.
Action. It is the chief external rotator of the humerus. This movement of
external rotation is through about 90°, and is of great importance. When the
elbow is bent, it produces the lateral movement of the hand by which, in writing, the
pen is carried from left to right across the page. When the elbow is extended, the
rotation of the humerus adds considerably to the range of rotatory movement
318
THE MUSCLES
enjoyed by the hand. The infra-spinatus also adducts the elevated arm, at the
same time drawing it slightly backwards, or extending it. It helps to hold the
head of the humerus in contact with the glenoid cavity.
Relations. Superficially, the infraspinous fascia which separates it from the
deltoid, trapezius, and latissimus dorsi; deeply, the suprascapular and dorsalis
FIG. 268.-BACK VIEW OF THE SCAPULAR MUSCLES AND TRICEPS.

Supra-spinatus
Infra-spinatus-
Teres minor-
Teres major-
Long head of triceps
Outer head of triceps
Inner head of triceps-
Anconeus
scapulæ vessels, and sometimes a small bursa which intervenes between its tendon
and the capsule of the shoulder joint; externally, the teres major and minor.
Variations. The slip from the under surface of the spine is frequently almost as
separate from the infra-spinatus as the teres minor, and sometimes there is no separation
between the infra-spinatus and teres minor.

TERES MINOR-SUBSCAPULARIS
319
4. TERES MINOR
The teres minor-named from its being the lesser of two somewhat cylindrical
muscles (teres round or cylindrical)-is a thick but narrow triangular or fan-shaped
sheet.
Origin. (1) The impression which occupies the upper two-thirds of the axillary
border of the infraspinous fossa; (2) septa which separate it from the infra-spinatus
behind, and from the long head of the triceps, the subscapularis, and the teres major
in front.
Insertion. (1) The lower of the three facets of the greater tuberosity of
the humerus and the posterior surface of that bone for one inch below the facet;
(2) the capsule of the shoulder joint.
Structure. From a fleshy origin which terminates in a point below, its fibres
diverge as they pass upwards and outwards to their insertion, which is by a short
strong tendon into the lowest facet of the tuberosity, and the capsule of the shoulder
joint; below the facet it is inserted by fleshy or very short tendinous fibres.
Nerve-supply. From the posterior cord of the brachial plexus (through the fifth
cervical nerve) by the lower division of the circumflex nerve which enters the muscle
upon its anterior surface near its insertion. The nerve is remarkable on account
of the ganglion upon its trunk shortly before it passes into the muscle.
Action.-The same as that of the preceding muscle, of which it may be con-
sidered to form a part. It will therefore rotate the arm outwards and at the
same time adduct.
Relations.-Behind, the deltoid; in front, the long head of the triceps, the teres
major, and subscapularis. Above and internally, the dorsalis scapulæ vessels run
between it and the axillary border of the scapula.

5. SUBSCAPULARIS
The subscapularis muscle-named from its position beneath the scapula-is a
thick triangular and somewhat multipenniform sheet.
Origin. (1) The whole of the ventral surface of the scapula with the exception
of the part near the neck, and the spaces at the upper and lower angles occupied by
the serratus magnus; (2) the lower two-thirds of the grooved outer border of the
scapula; and (3) the intermuscular septum between it and the teres minor and
major muscles.
Insertion. (1) The lesser tuberosity of the humerus, and the part of the shaft
immediately below it; (2) the front of the capsular ligament of the shoulder joint.
Structure. Its origin is by fleshy fibres from the surface of the bone, and also
by bipenniform bundles from the upper and lower surfaces of three or four septa
which are attached to the transverse ridges upon the venter scapulæ, so that the
whole muscle has a multipenniform arrangement. The fibres converge upwards
and outwards upon a strong tendon which is hidden by fleshy fibres to within an
inch of its insertion, the lower part of which is also fleshy. A bursa intervenes
between the tendon and the base of the coracoid process, and is usually in con-
nection with the shoulder joint.
Nerve-supply. From the posterior cord of the brachial plexus (through the
fifth and sixth cervical nerves), by the short and part of the lower subscapular
nerves. They enter the front surface of the muscle, the former near its upper,
the latter near its outer border.
Action. It is the chief internal rotator of the humerus; at the same time it
adducts it after it has been elevated. It also has an important influence in



320
THE MUSCLES
strengthening the shoulder joint by drawing the head of the humerus towards the
glenoid cavity.
Relations. Its anterior and internal face forms the greater part of the posterior
wall of the axilla, and is in contact with the serratus magnus, the short head of the
biceps, and the coraco-brachialis, the axillary vessels with many of their branches, the
brachial plexus and its branches, the lymphatic glands and vessels; its outer border
lies in contact with the teres major, the posterior circumflex and dorsalis scapulæ
vessels, and the circumflex nerve; behind lie the long head of the triceps and the
teres minor muscle, and the bursa which intervenes between its tendon and the
capsule of the shoulder joint.
Variations. Occasionally a separate slip arises from the axillary border of the scapula,
and is inserted into the capsule of the shoulder joint or into the humerus.
CLAVICLE
CORACOID
PROCESS
Supra-
spinatus
FIG. 269.-FRONT VIEW OF THE SCAPULAR MUSCLES.
Deltoid
Coraco-brachialis and short
head of biceps
Pectoralis
major
Subscapu-
laris
Teres major
Latissimus
dorsi
etrologeerde
Teres
major
6. TERES MAJOR
The teres major-named from its somewhat cylindrical shape and its size-
is a thick ribbon-shaped muscle.
-
Origin. (1) The oval facet which occupies the lower third of the axillary
border of the infraspinous fossa; (2) the infraspinous fascia and the inter-
muscular septa, which separate the muscle from the teres minor and infra-spinatus.
Insertion. The inner lip of the bicipital groove from the lower border of the
lesser tuberosity for about two inches down the humerus.
Structure. Its origin is by fleshy fibres which pass upwards, outwards and
somewhat forwards, to be inserted by a strong tendon, which is first visible upon the
outer border, and then upon the anterior surface of the muscle, and which is in
close relation with the back of the tendon of the latissimus dorsi. A small bursa
intervenes between the two tendons.
Nerve-supply. From the posterior cord of the brachial plexus (through the
sixth and seventh cervical nerves) by the lower subscapular nerve, which enters the
muscle upon its anterior aspect close to the middle of its inner border.
Action. It assists the latissimus dorsi as a strong adductor, and in some posi-
tions of the arm as an internal rotator of the humerus.
When the arm is fixed it will act with the latissimus dorsi in drawing the body
TERES MAJOR-CORACO-BRACHIALIS
321
upwards, as in climbing. Its influence, however, will be exerted upon the lower angle
of the scapula, while that of the latissimus dorsi is chiefly upon the trunk and pelvis.
Relations. In front lie the latissimus dorsi, both heads of the biceps, the
coraco-brachialis, the pectoralis major, the axillary vessels, and the lower branches
of the brachial plexus; behind, the latissimus dorsi, teres minor, infra-spinatus,
the long and outer heads of the triceps; between its upper border and the sub-
scapularis muscle are the posterior circumflex and dorsalis scapulæ vessels, and
the circumflex nerve; below are the superior profunda vessels and musculo-spiral
nerve.
7. CORACO-BRACHIALIS
The coraco-brachialis-named from its attachment to the coracoid process and
the upper arm (brachium)-is a cylindrical muscle, but somewhat fusiform at
the extremities.
Origin. (1) The tip of the coracoid process; (2) the inner side of the tendon
of the short head of the biceps.
Insertion.-(1) The rough impression two or three inches long upon the inner
border of the humerus in its middle third, and in front of the internal intermuscular
septum (see page 322); (2) the internal intermuscular septum and an aponeurotic
band which extends upwards from the septum in front of the tendons of the teres
major and the latissimus dorsi to the lesser tuberosity of the humerus.
Structure. It arises from the coracoid process by a short tendon, which is
blended upon its inner side with the insertion of the pectoralis minor, and from
the short head of the biceps by fleshy fibres for three or four inches below the
coracoid process. From this origin the fibres run parallel to one another, and are
inserted by a short tendon. The muscle is frequently divided into two planes between
which the external cutaneous nerve passes.

-
Nerve-supply. From the outer cord of the brachial plexus (through the
seventh cervical nerve) by the external cutaneous branch, which either pierces it
about the middle upon its way to the biceps and brachialis anticus, or sends a
branch to it in this position, while the rest of the nerve passes in front of the
muscle.
Action. To adduct and flex the humerus. As it lies at so small an angle with
the axis of that bone, it assists materially in pressing the head of the humerus
against the glenoid cavity, and so helps to prevent dislocation.
Relations. Superficially, the deltoid and pectoralis major; deeply, the sub-
scapularis, latissimus dorsi, teres major and triceps. Upon its outer side lies the
short head of the biceps; upon its inner side the pectoralis minor, the axillary and
brachial vessels, with the median nerve and other branches of the brachial plexus.
Variations. The coraco-brachialis varies chiefly in its insertion, which may extend as
high as the capsule of the shoulder or the lesser tuberosity, occasionally forming in this
position a separate muscle (the rotator humeri); or it may descend as low as the inner
condyle. It sometimes sends a slip to the triceps or brachialis anticus.
GROUP OF MUSCLES WHICH MOVE THE ELBOW JOINT
FASCIA OF THE UPPER ARM
The deep fascia of the upper arm forms a strong tube, thicker upon the posterior
than the anterior aspect, enclosing all the muscles and most of the vessels and nerves.
Above, it is continuous on the outer side and front with the fascia covering the
deltoid and pectoralis major, and internally with the axillary fascia. In the lower
two-thirds of the upper arm it is joined upon its deep aspect by two strong
Y
322
THE MUSCLES
processes: the external intermuscular septum, which arises from the external con-
dylar ridge and the outer border of the humerus; and the internal intermuscular
septum, which arises from the internal condylar ridge and the inner border of the
humerus. The tube formed by the deep fascia is thus divided by the bone and these
two septa into two compartments. In the front compartment are placed the flexors
of the elbow-joint, and in the back compartment the great extensor muscle.
FIG. 270.-SUPERFICIAL VIEW OF THE FRONT OF THE UPPER ARM.

Pectoralis minor
Coraco-brachialis
Deltoid
Biceps
Outer head of triceps
Inner head of triceps-
Brachialis anticus
Brachialis anticus
Semilunar fascia
Extensor carpi radialis
longior
Brachio-radialis
FLEXORS OF THE FOREARM
The flexor muscles are three in number. The most superficial is the biceps,
which arises from the scapula; while more deeply lie the brachialis anticus and
brachio-radialis (supinator longus), which arise from the humerus.

BICEPS
323
1. BICEPS
The biceps flexor cubiti-named from its two heads and its action-is a
thick, somewhat flattened fusiform muscle with a bifid upper extremity.
-
Origin. (1) The short head from the outer side of the tip of the coracoid
process, in close connection with the coraco-brachialis muscle; (2) the long
head, from the upper border of the glenoid fossa of the scapula and from the
glenoid ligament.
Insertion.-(1) The posterior border of the tubercle of the radius; (2) the
upper part of the deep fascia on the front of the forearm, two inches below the
inner condyle of the humerus.
Structure. The short head arises by a short tendon from which the fleshy fibres
diverge in a somewhat conical form until they meet and blend with the outer and
longer head about the middle of the upper arm.
The long head arises by a thick ribbon-like tendon three to four inches long,
which at its origin upon the upper border of the glenoid fossa bifurcates and
blends with the glenoid ligament of the shoulder joint. It first passes outwards
and arches over the rounded head of the humerus. It afterwards enters the canal
formed by the bicipital groove internally, and externally by the capsule of the joint,
together with the aponeurotic expansion derived from the tendon of the pectoralis
major. Down to this point it is invested by synovial membrane, which is reflected
upon it from the adjacent bone and capsule. After emerging at the lower end of
the bicipital groove it gives origin to a conical mass of fleshy fibres, which meet
with the fibres derived from the shorter head about the middle of the upper arm.
The fleshy bundles belonging to the two heads may be separated for a considerable
distance by careful dissection. Shortly below the middle of the upper arm, the
tendon of insertion commences as a septum between the two bellies of the muscle.
It rapidly increases in thickness, and about the level of the condyles it becomes
free, and as a flattened cord passes down in the middle of the bend of the elbow
and turns upon itself so that its posterior aspect now becomes external; before its
insertion into the posterior border of the tubercle of the radius it is separated from
that process by a small synovial bursa. About an inch and a half from its inser-
tion it gives off from its inner border a strong band of fibrous tissue three-quarters
of an inch broad and one inch long (the semilunar fascia), to the deep fascia
covering the ulnar surface of the forearm.
Nerve-supply. From the outer cord of the brachial plexus (through the sixth
and seventh cervical nerves) by a branch of the external cutaneous nerve which
enters the muscle on its posterior aspect near its inner border.
Action. (1) It flexes the elbow joint by means of its radial insertion, and also
by the attachment of the semilunar fascia to the inner side of the forearm. (2) It
supinates strongly the forearm by means of the radial tendon which wraps round the
tubercle of the radius. This movement will be most powerful when the elbow is
bent to a right angle, as the tendon is then perpendicular to the bone, which it causes
to revolve. To increase its leverage, the tendon is lifted away from the axis of the
bone by the prominence of the tubercle. (3) It will assist somewhat feebly in the
movements of the shoulder joint, its short head being, like the coraco-brachialis, a
flexor and adductor of the upper arm. By its long head it binds down the upper
portion of the humerus, and prevents the tendency to dislocation upwards. When
the forearm is fixed, the biceps will help in flexing the elbow, as in climbing or in
drawing up the trunk to a horizontal bar.
Relations. Superficially, the deltoid and pectoralis major, the deep fascia, and
in the bend of the elbow the median cephalic vein; deeply, the humerus, the


Y 2

324
THE MUSCLES
brachialis anticus, and supinator brevis; upon its inner side lie the coraco-
brachialis, the brachial vessels, and median nerve.
The semilunar fascia separates
the median basilic vein from the brachial vessels and median nerve.
girol
FIG. 271.-DEEP VIEW OF THE FRONT OF THE UPPER ARM.
Pectoralis minor-
Short head of biceps-
Coraco-brachialis-
Long head of triceps.
Inner head of triceps
Long head of biceps
Insertion of pectoralis major
Insertion of deltoid
wed
Internal intermuscular septum
Brachialis anticus
Band
Insertion of biceps
Outer part of brachialis anticus
Variations. The origin of the biceps is remarkably variable. Sometimes one of the
heads is deficient. More often a third head is derived from the middle of the inner
border of the humerus, and sometimes as many as three additional heads have been found
arising from the humerus. Occasionally it sends slips to the internal intermuscular
septum, internal condyle, or coronoid process.
BRACHIALIS ANTICUS-BRACHIO-RADIALIS
325
$1/2. BRACHIALIS ANTICUS
The brachialis anticus-named from its intimate relation with the front surface
of the bone of the upper arm (brachium)-is a thick, somewhat fusiform sheet,
curved from side to side to fit on to the convex anterior surface of the humerus,
and slightly bifid above.
Origin. The whole of the lower three-fifths of the front surface of the humerus,
with the exception of the small space on its inner aspect occupied by the coraco-
brachialis and the impression upon the outer aspect for the deltoid muscle, upon
either side of which it sends up two small pointed processes; (2) the front of the
internal intermuscular septum; (3) a small portion of the upper part of the front of
the external intermuscular septum above the point where it is pierced by the
musculo-spiral nerve.
Insertion. The inner and lower part of the rough triangular impression upon
the front of the coronoid process of the ulna.
Structure. The greater part of its origin is by fleshy fibres which converge
upon a tendinous sheet which makes its appearance at first upon the anterior
surface of the muscle, just above the level of the elbow joint. This tendinous
sheet receives the converging fleshy fibres upon its posterior aspect, and becomes
gradually thicker until it forms a very strong tendon of insertion which is closely
connected with the front of the anterior ligament of the elbow joint. The lower
and outer portion of the muscle is deeply grooved by the brachio-radialis (supinator
longus), so that it often looks like a separate muscle.
Nerve-supply. (1) From the external cord of the brachial plexus (through the
sixth cervical nerve) by branches of the external cutaneous nerve which enter
the anterior surface of the muscle near the inner border of its upper third;
(2) from the posterior cord of the brachial plexus (through the seventh cervical
nerve) by a small filament from the musculo-spiral nerve which enters the front of
that part of the muscle which is concealed by the origin of the brachio-radialis
(supinator longus).
Action.-To flex the ulnar half of the forearm. Like the biceps, it will form a
lever of the third order, but with much mechanical disadvantage on account
of the proximity of its insertion to the axis of the elbow joint. There will be,
however, a proportional gain in speed and range of movement.
Relations. In front, the deep fascia on the outer side of the arm which
separates it from the cephalic vein, the biceps, coraco-brachialis, deltoid, brachio-
radialis, (supinator longus), and extensor carpi radialis longior, the brachial vessels,
median and musculo-spiral nerves; behind, the triceps and elbow joint.
Variations. The brachialis anticus is sometimes divided into two heads by a continua-
tion of the cleft between the two pointed processes above mentioned, or by a separation
of a part of the outer half. Occasionally it gives off muscular slips to the radius or
the fascia of the forearm, also to adjacent muscles such as the pronator teres, the brachio-
radialis, and the extensor carpi radialis longior.

3. BRACHIO-RADIALIS
goola abrange
adwon
The brachic-radialis (supinator longus) is described with the radial group of
muscles (page 339).
326
THE MUSCLES
EXTENSORS OF THE FOREARM
The extensor muscles are two in number-the triceps and the anconeus.
1. TRICEPS
The triceps extensor cubiti-named from its three heads and its action-forms
a thick fusiform sheet wrapping round the posterior surface of the humerus in its
whole length.
Origin. The long head arises from the lower edge of the glenoid cavity and
the axillary border of the scapula for one inch below it.
The external head arises (1) from the posterior surface of the humerus above
the musculo-spiral groove, reaching as far up as the base of the greater tuberosity
and the insertion of the teres minor; (2) from the back of the external inter-
muscular septum above the point where it is pierced by the musculo-spiral nerve.
The internal head arises (1) from the whole of the posterior surface of the
humerus between the musculo-spiral groove and the olecranon fossa; (2) on the
inner side, from the back of the whole of the internal intermuscular septum; (3)
on the outer side, from the back of that portion of the external intermuscular septum
which lies below the point where it is pierced by the musculo-spiral nerve.
—
Insertion. (1) The posterior part of the upper surface of the olecranon process;
and (2) on either side by aponeuroses which are continuous with the deep fascia at
the back of the forearm.
Structure. The long head forms a strong fusiform muscular band, arising by
tendinous fibres which blend with the lower part of the capsule of the shoulder
joint. The surfaces of the band at first look inwards and outwards. The tendon
of origin extends for some distance further on the inner than on the outer surface.
As the muscular band passes downwards, it twists upon itself so that what was the
internal surface now becomes posterior, and the external surface becoming the
anterior is applied to the back of the rest of the muscle. Upon this anterior
surface the common tendon of insertion begins as a broad aponeurosis about three
inches from the scapula, and receives the fleshy fibres of the long head in penni-
form fashion chiefly upon its upper border and posterior surface. These fleshy
fibres are continued as a thick band along the inner border of this common tendon,
and terminate in a blunt point a little below the junction of the middle and lower
thirds of the arm.
The external head arises by fleshy fibres which are inserted in penniform
fashion into the outer border of the common aponeurosis. The lowest of these fibres
arise from a tendinous arch which bridges over the musculo-spiral nerve.
The internal head, which is much stronger than the outer, forms a thick
triangular sheet, wrapping round the back of the bone, and arising also from the
back of the intermuscular septa on either side. The apex of this triangle extends
upwards along the lower border of the musculo-spiral groove to a point just
below the insertion of the teres major. Its fleshy fibres pass downwards and
somewhat backwards to the broad aponeurosis, which, after receiving the fleshy
fibres from the outer and long heads, completely covers the whole of the posterior
surface of the muscle in the lower third of the arm. A few fleshy fibres of this
head are inserted directly into the bone, and the adjacent posterior ligament; the
latter slip is sometimes called the subanconeus.
The insertion of the tendon into the back part of the upper surface of the
olecranon is usually separated from the adjacent part of the olecranon and
ANCONEUS
327
That part of the
the posterior ligament of the elbow joint by a small bursa.
aponeurotic continuation of the tendon which lies between the olecranon process
and the back of the external condyle is by far the stronger.
-
Nerve-supply. From the posterior cord of the brachial plexus (through the
seventh and eighth cervical nerves) by means of the musculo-spiral, which supplies
branches to the long and inner heads in the first part of its course; and numerous
other branches to the inner and outer heads while passing through the musculo-
spiral groove.
Action.-To extend the elbow joint, the muscle acting as a lever of the first
order, at a very great mechanical disadvantage on account of the short distance
which intervenes between the olecranon process and the axis of the elbow joint;
but at the same time with a great gain in speed and range of movement.
Hence this muscle is the chief agent in movements of the arm in which great
speed is attained, such as in throwing a stone or striking a blow. The long head
has some influence as an adductor of the shoulder joint; it has also a supple-
mentary ligamentous action upon that joint similar to that of the coraco-brachialis
by holding the head of the humerus in close contact with the glenoid cavity. As
it passes over both the shoulder and the elbow joints, the long head enables the
powerful abductors of the shoulder to exert a peculiar influence upon the extension
of the elbow joint. If it were merely a passive ligament, the long head would
extend the elbow whenever the humerus was abducted by the deltoid muscle. As,
however, the long head contracts at the same time with the deltoid, we have an
apparatus by which, so to speak, a double rapidity of extension is secured for the
elbow joint. This attachment, therefore, of the long head of the triceps to the
scapula is the chief cause for the rapid movements of the lower end of the forearm
which are made use of in throwing and striking.
Acting from below, the triceps will extend the upper arm upon the forearm, as
in the use of the parallel bars, and in many other gymnastic exercises.
Relations. The long head lies behind the subscapularis, teres major, and latis-
simus dorsi, in front of the teres minor, with the dorsalis scapulæ vessels upon its
posterior, and the posterior circumflex vessels and the circumflex nerve upon its
anterior border. Lower down, the posterior surface of the muscle is only separated
from the integuments by the deep fascia; in front lie the brachialis anticus, brachio-
radialis (supinator longus), extensor carpi radialis longior, and coraco-brachialis,
with the superior profunda vessels and musculo-spiral nerve. A small bursa inter-
venes between the tendon and part of the olecranon process. The muscle is also in
relation with the shoulder and elbow joints.
Variations. The internal head sometimes arises as high as the greater tuberosity. An
additional slip is occasionally received from the capsule of the shoulder joint, the coracoid
process, or the tendon of the latissimus dorsi. A slip of muscle is frequently separated
from the lower border of the internal head, and, passing from the inner condyle to the
olecranon, bridges over the ulnar nerve.
2. ANCONEUS
The anconeus is described with the MUSCLES ON THE BACK OF THE FOREARM
(page 345).

MUSCLES OF THE FOREARM
добав
The muscles of the forearm are enveloped by a strong deep fascia which is con-
tinuous with that of the upper arm. It is thickest upon the posterior aspect, where
it is attached to the sides of the triangular posterior surface of the olecranon,
and to the whole of the posterior ridge of the ulna. Below the internal condyle
328
THE MUSCLES
it receives the broad band of the bicipital fascia; and behind, the aponeurotic inser-
tion of the triceps. In the bend of the elbow it is pierced by a communicating
vein. On the outer side and back of the forearm the deep fascia has numerous
connections with the longitudinal ridges of the lower end of the radius and ulna.
It also becomes much thickened by the addition of transverse bands, so as to
form the posterior annular ligament, which passes from the outer border of the
lower end of the radius, inwards and at the same time a little downwards, to the
ulnar border of the carpus, where it is attached to the inner side of the pisiform
and cuneiform bones. On its anterior surface this ligament is attached to the
ridges upon the back of the lower extremity of the radius, and so forms canals.
through which pass the tendons of the long muscles upon the radial border and
posterior surface of the forearm. The ligament is also in contact with the lower
end of the ulna, which it binds in its place, much in the same manner as the head
of the radius is held in position by means of the orbicular ligament, but it has no
insertion into this bone.
In the front of the wrist the deep fascia forms a thin layer, which overlies the
anterior annular ligament. The latter is sometimes described as a thickening of
the same fascia, but really it is continuous with a thin aponeurosis which separates
the first and second layers of the muscles of the forearm shortly to be described.
It is a strong band of fibrous tissue, which stretches transversely from the pisiform
bone and unciform process on the ulnar side of the carpus to the scaphoid and
the trapezium on the radial side.
MUSCLES OF THE FRONT OF THE FOREARM
The muscles upon the front of the forearm form four planes or layers: the first
two layers having their origins from the front of the internal condyle; the last
two from the bones of the forearm alone.
FIRST LAYER
The first layer consists of four muscles-the pronator radii teres, flexor
carpi radialis, palmaris longus, and flexor carpi ulnaris--which all arise by a
common tendon from the front of the internal condyle, and by separate attach-
ments from the deep fascia of the forearm and the intermuscular septa; while
the innermost and outermost have additional origins from the ulna.
1. PRONATOR RADII TERES
The pronator radii teres-named from its action and somewhat cylindrical
shape-is a thick ribbon-shaped muscle.
Origin. First head: (1) by the common tendon from the front of the internal
condyle; and (2) from about half an inch of the lowest part of the internal
condylar ridge; (3) from the deep fascia covering it, and the intermuscular septum
which separates it from the flexor carpi radialis and the flexor sublimis digitorum.
Second head: from the inner border of the coronoid process.
Insertion. The rough impression on the middle of the outer surface of the
radius.
Structure. The higher of the two heads, which is much the larger, arises partly
by a short tendon, and partly by muscular fibres, and is separated from the lower
head by a small tendinous arch through which passes the median nerve. The
lower head, which lies concealed by the rest of the muscle, arises by a small

PRONATOR RADII TERES
329
aponeurotic band. The thick fleshy muscle passes obliquely downwards and out-
wards across the front of the forearm. Below the middle of its anterior surface
begins the tendon of insertion, which expands and covers the whole of the muscle
FIG. 272.-FRONT OF THE FOREARM: FIRST LAYER OF MUSCLES.

Triceps-
Brachialis anticus-
- Biceps
Pronator radii teres
Brachio-radialis
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
Flexor longus pollicis
Flexor sublimis digitorum
for a short distance before it is inserted by a strong fibrous band into the special
impression for it upon the most prominent portion of the outward curve of the
radius.
330
23 THE MUSCLES
Nerve-supply. From the outer and inner cords of the brachial plexus (through
the sixth cervical nerve) by means of filaments derived from the median nerve just
before it passes through the arch between the two heads. These filaments enter
the muscle at its deep surface a short distance above the middle of its outer border.
Action. (1) To pronate the forearm. In supination, the tendon is to some
extent wrapped round the radius, as the tendon of the biceps is in pronation. In
contraction the muscle, so to speak, unwraps itself and so causes the radius to
revolve around the axis, which passes through the middle of its head and the lower
end of the ulna. Its insertion into the convexity of the curve of the radius places
the line of the muscle as far as possible from this axis, and so gives it some
mechanical advantage. On the other hand, the obliquity of its insertion diminishes
the power of the muscle, and is one of the causes which make pronation a more
feeble movement than supination. (2) It will also assist in the flexion of the
forearm.
Relations.
Superficially, the deep fascia and superficial veins, the radial vessels
and nerve, and, lower down, the brachio-radialis (supinator longus) and radial
extensors. Deeply, the brachialis anticus, flexor sublimis digitorum, supinator
brevis, and the median nerve. By its outer border it forms the inner boundary of
the bend of the elbow, and by its inner border it is in contact with the flexor carpi
radialis.
Variations. The pronator radii teres frequently extends at its origin for some distance
further up the internal condylar ridge. It may also receive a separate head from the
internal intermuscular septum, the inner border of the humerus, or an abnormal supra-
condylar process; sometimes also from the biceps or brachialis anticus. This third head
bridges over the brachial artery and median nerve.
2. FLEXOR CARPI RADIALIS
The flexor carpi radialis-named from its action as a flexor of the wrist and
its position on the radial side of the joint-is flat and fusiform.
Origin. (1) The common tendon from the front of the internal condyle;
(2) the deep fascia and the intermuscular septa which lie between the muscle and
the pronator radii teres, the flexor sublimis digitorum, and the palmaris longus.
Insertion. The front of the base of the second metacarpal bone; and usually
by a smaller slip into that of the third as well.
Structure. Its fleshy fibres are contained in an aponeurotic case which forms
an elongated four-sided pyramid, the apex being at the internal condyle, and
the sides consisting of the deep fascia and the intermuscular septa which intervene
between it and the adjacent muscles. The fleshy fibres converge downwards and
somewhat outwards upon the back of the tendon which begins at the junction of
the upper and middle thirds of the forearm, and is free soon after the middle of the
forearm.
At the wrist the tendon passes through a special compartment external to the
tube formed by the anterior annular ligament. This compartment is bounded
behind by the scaphoid bone and the groove upon the trapezium; externally, by
the tuberosity of the scaphoid bone and the ridge upon the trapezium; and in
front and internally by a thickening of the deep fascia of the forearm. It is lined
by a special synovial membrane.
Nerve-supply. From the outer and inner cords of the brachial plexus (through
the sixth cervical nerve) by filaments from the median nerve which pass to its
posterior surface in its upper third.
Action.-(1) To flex the wrist. By its insertion into the metacarpus it
bends not only the radio-carpal joint (which is the wrist joint proper), but also the
intercarpal and the carpo-metacarpal joints, which really take part in all the
PALMARIS LONGUS-FLEXOR CARPI ULNARIS
331
movements of what may be called the wrist as distinguished from the wrist joint.
(2) When the hand is fully supinated, it helps in pronation. (3) It is also a feeble
flexor of the elbow.
Relations. Superficially, the deep fascia and the superficial veins; deeply, the
flexor sublimis digitorum, the flexor longus pollicis, the median nerve, the wrist and
some of the carpal joints; on the outer side of it lie the pronator radii teres and
the radial vessels; on the inner side it is in contact above with the palmaris longus.
Variations. The flexor carpi radialis may have a second origin from the tendon of
the biceps or the radius, and its insertion may be extended to the base of the fourth
metacarpal bone or to some of the bones of the carpus. It is sometimes absent.
3. PALMARIS LONGUS
The palmaris longus-named from its length and its insertion upon the palm
of the hand-is flat and fusiform.
Origin. (1) The common tendon from the front of the internal condyle; (2)
the deep fascia of the forearm; and (3) the septa which lie between the muscle and
the flexor carpi radialis, the flexor carpi ulnaris, and the flexor sublimis digitorum.
Insertion. (1) The upper end of the strong central portion of the palmar fascia;
(2) the lower part of the front of the anterior annular ligament; and (3) the deep
fascia covering the thenar eminence.
Structure.-Like the preceding muscle it consists of fleshy fibres which rise in
a long four-sided pyramid from the aponeurotic case formed by the deep fascia and
the intermuscular septa. Its tendon appears first upon the anterior surface of the
muscle at the junction of the middle and upper thirds of the forearm, and is free about
the middle of the forearm. It passes almost directly downwards to the middle of
the wrist, where it descends in front of the upper part of the anterior annular
ligament, and then becomes attached to its lower edge as well as the adjacent fasciæ.
Nerve-supply. From the outer and inner cords of the brachial plexus (through
the eighth cervical nerve) by filaments from the median nerve which enter the deep
surface of the muscle.
Action.-(1) To flex the wrist; (2) to a slight extent to flex the elbow also;
(3) it makes tense the central portion of the palmar fascia, so that when an object
is grasped firmly by the fingers no injurious pressure is exerted upon the important
vessels and nerves which lie beneath that structure; (4) its attachments to the
fascia of the thenar eminence gives a firm origin to some of the short muscles of
the thumb.
Relations. Superficially, the deep fascia and superficial veins; deeply, the
flexor sublimis digitorum and median nerve, and the upper part of the anterior
annular ligament.
Variations. The palmaris longus is very variable. It may be double, and it is often
absent. The fleshy belly is sometimes below, and the tendon in part or entirely above.
It may take an additional head from the radius or the coronoid process. Its insertion may
be into the fascia of the forearm, the flexor carpi ulnaris, the short muscles of the little
finger, or one of the carpal bones.


4. FLEXOR CARPI ULNARIS
The flexor carpi ulnaris-named from its influence upon the wrist and its
position-is a thick sheet of muscular fibre, somewhat fusiform in shape, which
wraps round the convex ulnar border of the forearm.
Origin. First head: (1) by the common tendon from the lower part of the
front of the internal condyle; (2) the deep fascia of the forearm, and the septa
332
THE MUSCLES
which intervene between the muscle and the palmaris longus and flexor sublimis
digitorum.
The second head: from the inner surface of the olecranon process, and the upper
two-thirds of the posterior border of the ulna.
Insertion. The upper surface of the pisiform bone, beyond which fibres are
continued to the unciform process, and the front of the base of the fifth metacarpal
bone.
Structure. The origin of the upper head is tendinous, and that of the lower is
partly fleshy, partly aponeurotic; the aponeurosis from the posterior ridge of the
ulna being common to it with the flexor profundus digitorum and the extensor carpi
ulnaris, and being closely blended with the deep fascia of the back of the forearm.
The two heads are united by a fibrous arch under which passes the ulnar nerve.
From this tendinous and bony origin the fleshy fibres pass downwards and forwards
in a penniform manner to be inserted into the posterior aspect of a tendon which
appears on the front of the muscle a little above the middle of the forearm, and
becomes free just above the wrist joint, where it lies superficial and internal to the
anterior annular ligament at its insertion into the pisiform bone.
Nerve-supply. From the inner cord of the brachial plexus (through the
eighth cervical and first thoracic nerves) by filaments from the ulnar nerve which
enter the deep surface of the muscle above the middle of the forearm.
Action.-(1) Flexor of the wrist. The pisiform bone assists this action by lifting
the line of the tendon a little from the metacarpal bone, much as the patella assists
the quadriceps femoris. (2) It assists somewhat feebly in adduction of the wrist.
(3) It helps in the flexion of the elbow.
Relations. Superficially, the deep fascia and superficial veins; deeply, the flexor
profundus digitorum, the ulnar vessels and nerve. Near the wrist the ulnar artery
lies along the outer border of the tendon.
Variations. Its insertion sometimes extends to the anterior annular ligament, and
occasionally it sends a slip to the base of the fourth metacarpal bone.
SECOND LAYER
The second layer consists of one muscle-the flexor sublimis digitorum.
FLEXOR SUBLIMIS DIGITORUM
The flexor sublimis digitorum-named from its action as a flexor of the fingers,
and from its position in relation to the deep flexor (sublimis = superficial)-is a
fusiform sheet, with two heads above, and dividing into four tendons below.
Origin. The first head arises from (1) the front of the internal condyle by
the common tendon; (2) the intermuscular septum which separates it from the
muscles of the first sheet; (3) the internal lateral ligament; and (4) a tubercle at
the upper part of the inner border of the coronoid process of the ulna.
The second head arises from the oblique line on the anterior surface of the radius.
Insertion. By four tendons into the middle of the sides of the second phalanges
of the four fingers.
-
Structure. The first head arises by short tendinous fibres from the humerus
and ulna, and from the ligament between them. The second head, which is much
smaller, by fleshy fibres which form a thin sheet covering a part of the flexor longus
pollicis. Between these two heads the median nerve and the ulnar artery are placed.
Converging from these two heads, the fleshy fibres occupy almost the whole breadth
of the forearm, but soon divide into a superficial and deep plane. From the former,


FLEXOR SUBLIMIS DIGITORUM
333
which contains the radial head and the more superficial fibres of the first head,
the tendons to the middle and ring fingers are derived. The tendon to the middle
finger receives the greater part of the radial head in penniform fashion, becoming
FIG. 273.-FRONT OF THE FOREARM: SECOND LAYER OF MUSCLES.

Biceps
Triceps
Muscles of first layer
Brachialis anticus
Flexor sublimis digitorum
Flexor carpi ulnaris
Flexor carpi radialis
Palmaris longus
Brachio-radialis
Extensor carpi radialis longior
-Supinator brevis
Brachio-radialis
-Flexor longus pollicis
-Extensor ossis metacarpi pollicis
Extensor brevis pollicis
free close to the anterior annular ligament. That to the ring finger separates high
up, and is soon free from fleshy fibres. The deeper plane of the muscle is crossed
by a strong tendinous intersection soon after its origin from the first head. It then
334
THE MUSCLES
gives off a fleshy band to join that part of the superficial plane which goes to the
ring finger, and afterwards bifurcates to form the tendons for the index and little
fingers. I am indebted to Professor Thane for calling my attention to this arrange-
ment. Beneath the anterior annular ligament the tendons of the superficial plane,
viz. those going to the middle and ring fingers, lie in front of the other two tendons.
Here they are invested by the synovial sheath or great palmar bursa, which is
common to them and the other tendons which pass through this space, and which
extends to about the middle of the palm. At the heads of the metacarpal bones
the tendons enter the vaginal sheaths of the flexors of the fingers, and each tendon
becomes concave behind to correspond with the convexity of the tendon of the deep
flexor upon
which it now rests. At the middle of the first phalanx the tendon splits,
FIG. 274.-DIAGRAM OF THE GREAT PALMAR BURSA.

Ulnar portion of palmar
bursa
Radial portion of palmar
bursa
Anterior annular ligament
-Lumbricalis
Deep
transverse
ligament
-Superficial
transverse
ligament
-Theca

and the halves separate to allow the passage of the tendon of the flexor profundus.
The two halves again unite opposite the base of the second phalanx in such a way
that the parts now in contact are a direct continuation of what were before the
borders of the tendon; while the parts of the tendon which correspond to its mesial
line above are now most widely separated. After a contact of about a quarter of an
inch, the halves of the tendon again separate in order to be attached to the sides of
the shaft of the second phalanx.
Nerve-supply. From the outer and inner cords of the brachial plexus (through
the seventh and eighth cervical and first thoracic nerves) by branches from the
median nerve which enter the deep surface of the muscle at its upper part.
Action. To flex the second phalanges of the four fingers.
Being inserted
FLEXOR PROFUNDUS DIGITORUM
335
very obliquely, it acts under a considerable mechanical disadvantage, but at the
same time the speed and range of movement corresponding to a slight contraction
of the muscle are very great. The size of the angle which it makes with the shaft
of the phalanx at its point of insertion is somewhat increased by the raising of its
tendon from the palmar aspect of the first phalanx by the tendon of the deep flexor.
After bending the second phalanx of the finger, it will bend also the metacarpo-
phalangeal joint; then the three joints which together produce flexion of the wrist;
and finally it will feebly assist in the flexion of the elbow joint.
Relations. Superficially, the four muscles of the first sheet and the radial
vessels and nerves; deeply, the flexor longus pollicis, flexor profundus digitorum,
and pronator quadratus, the ulnar artery and vein, and the median nerve. In the
hand, it lies beneath the anterior annular ligament, the palmar fascia, and the
superficial palmar arch, and upon the tendons of the flexor profundus digitorum
with the lumbricales.
Variations. The flexor sublimis digitorum varies very little in its origin. It has been
seen to arise partly from the pronator radii teres. Occasionally its tendon to the little
finger fails, and the place of this tendon may be taken by a lumbricalis or a special slip from
the flexor profundus. Sometimes accessory heads join the tendons in the hand from the
flexor profundus or the annular ligament.
THIRD LAYER
The third layer consists of two muscles-the flexor profundus digitorum and the
flexor longus pollicis-which arise from the ulna and radius respectively.
1. FLEXOR PROFUNDUS DIGITORUM
The flexor profundus digitorum-named from its action upon the fingers and
its relation to their superficial flexor-is a strong fusiform sheet of muscular fibres
which wraps round the anterior and inner surfaces of the ulna, and divides below
into four tendons for the fingers.
Origin. (1) The upper three-fourths of the anterior surface of the ulna; and
(2) the adjacent part of the interosseous membrane; (3) the upper two-thirds
of the inner surface of the ulna; and (4) the posterior ridge of that bone by the
aponeurosis common to it, the flexor carpi ulnaris, and the extensor carpi ulnaris.
Insertion. The front of the bases of the third phalanges of the four fingers.
Structure. Arising directly from the bones and fibrous structures which form
the origin of the muscle, the fleshy fibres converge below upon the back of four
tendons, which, appearing about the middle of the forearm, become free at the
upper border of the anterior annular ligament. That part of the muscle which is
inserted into the index finger is separable from the rest of the muscle in nearly the
whole of its extent; the part to the little finger is also generally more separable
than that to the other two fingers. As they pass beneath the anterior annular
ligament, the tendons are invested by the common synovial sheath. At the meta-
carpo-phalangeal joints they enter the vaginal sheaths belonging to their respec-
tive fingers. Opposite the first phalangeal joint each tendon passes through the
opening formed by the splitting of the flexor sublimis tendon; and on the palmar
aspect of the second phalanx it passes over a slight elevation formed by the union
of the two halves of the companion tendon before they are inserted into the sides
of the second phalanx. The deep tendon finally passes over the second phalangeal
joint, to be inserted into the front of the base of the third phalanx. In the palm
of the hand the lumbricales (which will afterwards be described) arise from the
tendons of the flexor profundus.


336
THE MUSCLES
Nerve-supply.-By two sources from the brachial plexus (through the eighth
cervical and first thoracic nerves):-(1) By the anterior interosseous branch of
the median nerve, which sends a filament to the portion of the muscle belonging
FIG. 275.-FRONT OF THE FOREARM: THIRD LAYER OF MUSCLES.

Biceps.
Muscles of the first and
second layers
Brachio-radialis
Brachialis anticus
Extensor carpi radialis longior
Supinator brevis
Flexor profundus digitorum-
Flexor longus pollicis
Brachio-radialis
Pronator quadratus-
Extensor ossis metacarpi
pollicis
Flexor carpi ulnaris
Extensor brevis pollicis
to the index finger, and part if not all of that belonging to the middle finger upon
the radial border of its anterior surface, about the middle of the forearm. (2) By
the ulnar nerve, which distributes branches to the rest of the muscle near the inner
border of the superficial aspect of the muscle in the upper part of the forearm.
FLEXOR LONGUS POLLICIS
337
Action. It is a powerful flexor of the third phalanges of the fingers. As with
the superficial flexor, the extreme obliquity of the insertion of the tendons gives
great speed and range of movement, but increases the mechanical disadvantage
with which this muscle (being a representative of the third order of lever) must act.
The slight elevation formed by the union of the two halves of each tendon of the
flexor sublimis upon the second phalanx diminishes to a small extent the extreme
obliquity of its insertion. After bending the third phalanx, the muscle will assist
in the flexion of the other phalanges and the wrist.
Relations.- Superficially, the flexor sublimis digitorum and flexor carpi ulnaris,
the ulnar vessels, the median and ulnar nerves; deeply, the pronator quadratus and
wrist joint. In the hand, it lies beneath the tendons of the flexor sublimis digitorum
and the lumbricales, and upon the adductor of the thumb, the interossei muscles,
and the deep palmar arch.
Variations. The flexor profundus digitorum frequently receives, like the flexor longus
pollicis, a slip from the superficial muscles of the forearm. Sometimes the part which
goes to the index finger may take part of its origin from the radius; and occasionally
slips may pass from the flexor profundus to the flexor longus pollicis, or vice versa. A
slip has been observed to end in the synovial membrane of the palmar bursa.

2. FLEXOR LONGUS POLLICIS
The flexor longus pollicis-named from its action upon the thumb and its
length as compared with the short muscles of the ball of the thumb-is a fusiform
sheet.
Origin. (1) The anterior surface of the radius below the oblique line, with the
exception of the last two inches of the surface; and the adjacent surface of the
interosseous membrane. (2) A second head arises from the inner border of the
coronoid process of the ulna, but occasionally it may come from the internal
condyle of the humerus.
Insertion. The front of the base of the last phalanx of the thumb.
Structure. A penniform muscle arising fleshy from the bone and the inter-
osseous membrane. The tendon first appears upon the anterior surface near to its
ulnar border about the middle of the forearm. It receives the fleshy fibres upon
its outer border and posterior surface and becomes free at the level of the wrist
joint, where it enters the canal formed by the anterior annular ligament and the
front of the carpus. It is here invested by a special compartment of the great
synovial bursa, and this compartment is continuous with the synovial sheath of the
tendon as it lies in the thumb. After entering the palm of the hand, the tendon
passes beneath the outer head of the flexor brevis pollicis, then through the groove
formed by the two sesamoid bones which belong to the tendons of this muscle,
and, after lying in close contact with the concave palmar surface of the first
phalanx of the thumb, it is inserted into the front of the base of the second
phalanx.
Nerve-supply. From the outer and inner cords of the brachial plexus (through
the eighth cervical and first thoracic nerves) by means of the anterior interosseous
branch of the median nerve, which sends filaments to it upon its anterior surface
near its ulnar border about the middle of the forearm.
Action. It is a powerful flexor of the last phalanx of the thumb. It will also
flex its metacarpo-phalangeal joint, and afterwards it will assist the other flexors
of the wrist.
As the bones of the thumb are not in the same plane with those of the fingers,
but rotated so that their palmar surface looks towards the rest of the hand, their
flexion will be accompanied by adduction; as when the thumb meets the other
Z

338
THE MUSCLES

fingers in picking up any small object, or in grasping anything between the fingers
and thumb.
Relations. Superficially, the flexor sublimis digitorum, flexor carpi radialis,
brachio-radialis (supinator longus), and the radial vessels; deeply, the pronator
quadratus and wrist joint. In the hand, after passing beneath the anterior annular
ligament, it is covered by the opponens pollicis and the outer head of the flexor
brevis pollicis, and it lies on the inner head of the flexor brevis pollicis.
Variations. Besides the communication with the flexor profundus digitorum, we
occasionally find slips passing from the tendon of the flexor longus pollicis to join the first
lumbricalis muscle. The second head may be absent, as in fig. 275.
FOURTH LAYER
The fourth layer consists of one muscle-the pronator quadratus.
PRONATOR QUADRATUS
The pronator quadratus (fig. 284) is a thin quadrilateral sheet, named from its
action and its nearly square shape.
Origin. The inner part of the front surface of the lower fourth of the ulna.
Insertion. The lower two inches or rather less of the outer border, the anterior
and the inner surfaces of the radius.
Structure. The greater part of the muscle consists of fleshy fibres which
pass transversely between its two attachments. Its inner third, however, is
covered by a strong aponeurosis which arises from the inner border of the ulna.
The radial insertion is of a somewhat triangular shape, the outer side of the triangle
passing obliquely from the interosseous line downwards, and joining the outer
border of the radius a short distance from the base of the styloid process; while the
inner side corresponds to the interosseous ridge, and the base crosses the front of
the radius above the attachment of the anterior radio-carpal ligament.
Nerve-supply.-From the outer and inner cords of the brachial plexus (through
the eighth cervical and first thoracic nerves) by means of the anterior interosseous
branch of the median nerve which terminates by filaments which enter the front
of the muscle near its upper border.
Action. By drawing the outer border of the anterior surface of the radius
Action.-By
towards the inner border of the anterior surface of the ulna, it pronates the radius
upon the ulna.adioillon
Relations. Superficially, the flexor longus pollicis, the flexor carpi radialis,
the flexor profundus digitorum, and the flexor carpi ulnaris, the radial and ulnar
arteries, and the ulnar nerve; deeply, the anterior interosseous artery, the inter-
osseous membrane, and the inferior radio-ulnar joint.
Variations. The pronator quadratus is sometimes absent. It sometimes gives off
slips to the scaphoid or trapezium, the base of the first metacarpal bone, or to the origins
of the short thumb muscles.

BRACHIO-RADIALIS
339
RADIAL GROUP OF MUSCLES
Along the radial border, between the groups which clothe the front and back of
the forearm, lie three long muscles, one upon the other-viz. the brachio-radialis
(or supinator longus); the extensor carpi radialis longior; and the extensor carpi
radialis brevior.

1. BRACHIO-RADIALIS
The brachio-radialis, or supinator radii longus-named from its attachment
to the humerus and radius, and sometimes called the supinator longus from an
erroneous view of its action-is a fusiform sheet.
Origin. The upper two-thirds of the external condylar ridge, and the front of
the external intermuscular septum of the upper arm.
Insertion. The base of the styloid process of the radius.
Structure.-Arising by fleshy fibres from the septum, and by short tendinous
fibres from the condylar ridge, the muscle passes downwards and forwards in penni-
form fashion to its tendon which lies first on its deep surface. Becoming free just
below the middle of the forearm, the tendon runs directly downwards and expands
before its insertion upon a horizontal line at the base of the styloid process of the
radius. At first the plane of the muscle is directed outwards and inwards; but
lower down the outer surface becomes anterior, and the inner posterior.
Nerve-supply.--From the posterior cord of the brachial plexus (through the
sixth cervical nerve), by branches from the musculo-spiral nerve which enter the
upper part of the muscle upon its inner surface.
Action. To flex the forearm. Its insertion at the lower end of the long arm
formed by the radius makes it one of the few examples of the second order of lever
when the muscle is used to raise only the weight of the forearm; but whatever
advantage is obtained by the position of this insertion is lost by the extreme
obliquity of the tendon. This obliquity (Introduction, page 300) will, however,
add speed and range of movement, and at the same time it will assist in drawing
the articular surfaces of the elbow together, and so give strength to the joint.
If the forearm be fully supinated, the contraction of the brachio-radialis will
cause some pronation; and it is only when the forearm is in the position of full
pronation that it will, produce a slight supination. It is therefore incorrect to
describe the muscle as a supinator.
Relations. In the upper arm, it has at its inner side the brachialis anticus,
in which it forms a deep groove, and the musculo-spiral nerve and superior pro-
funda vessels. Outside and behind lies the inner head of the triceps. Below, it
rests on the upper border of the extensor carpi radialis longior. In the forearm it
is covered, above by the deep fascia and superficial veins; below, by the extensor
ossis metacarpi and the extensor brevis pollicis. Beneath it lie the extensor
carpi radialis longior, the supinator brevis, the pronator radii teres, the flexor
sublimis digitorum, the flexor longus pollicis, the radial vessels and nerve.
Variations. The brachio-radialis is sometimes absent. It may receive a slip from the
brachialis anticus. It may give slips to various parts of the radius, to the carpal bones
on the radial side of the hand, to the tendons of the extensor carpi radialis longior, the
extensor ossis metacarpi pollicis, the flexor longus pollicis, or to the supinator brevis
muscle.


z 2
340
THE MUSCLES
FIG. 276.-MUSCLES OF THE RADIAL SIDE AND THE BACK OF THE FOREARM.

Biceps
Brachialis anticus
Brachio-radialis
Extensor carpi radialis longior-
-Triceps
Anconeus
Extensor communis digitorum-
Flexor carpi ulnaris
Extensor carpi ulnaris

Extensor carpi radialis brevior.
Extensor minimi digiti
Extensor ossis metacarpi.
pollicis
Extensor brevis pollicis
ULNA
Extensor longus pollicis.

EXTENSOR COMMUNIS DIGITORUM
341
2. EXTENSOR CARPI RADIALIS LONGIOR
The extensor carpi radialis longior-named from its action, position, and length
in comparison with its fellow extensor-is a narrow fusiform sheet.
Origin. (1) The lower third of the external condylar ridge; (2) the front of the
external intermuscular septum; (3) the front of the common tendon by which the
extensors at the back of the forearm arise from the external condyle.
Insertion. The back of the base of the second metacarpal bone near its
radial border.
Structure.-Arising
Structure. Arising by fleshy fibres, this muscle has a somewhat penni-
form arrangement. Its tendon is first seen near the outer border on the deep
surface of the muscle, and becomes free at the junction of the middle and upper
thirds of the forearm. It lies upon and in close association with the tendon of
the short extensor, and passes through the second compartment in the posterior
annular ligament to its insertion upon the metacarpal bone. Its surfaces, like those
of the preceding muscle, are at first directed outwards and inwards, and afterwards
forwards and backwards.
Nerve-supply. From the posterior cord of the brachial plexus (through the
sixth cervical nerve), by a branch from the musculo-spiral nerve which enters the
muscle at the upper part of its deep surface.
Action.-(1) To extend the wrist; including under this appellation the carpo-
metacarpal, intercarpal, and radio-carpal joints. It is also a slight abductor of
these joints. When the fingers have to be bent by the long flexors, it steadies
the carpus so as to limit the action of the flexors to the phalanges. (2) It has
also some influence in flexion of the elbow joint.
Relations. In the arm, it lies between the brachialis anticus and the triceps,
and it is covered by the brachio-radialis. In the forearm, it overlies the short
radial extensor and wrist joint, while it lies beneath the brachio-radialis and the
extensors of the thumb.
Variations. The extensor carpi radialis longior may be united with the brevior. It
may give tendinous slips to the bases of the first or third metacarpal bones, or to the
trapezium; or a slip may join the extensor ossis metacarpi pollicis, or some of the
interossei.

3. EXTENSOR CARPI RADIALIS BREVIOR
The extensor carpi radialis brevior-named for similar reasons to those which
give its name to the preceding muscle-is also flat and fusiform.
Origin. (1) The common tendon attached to the external condyle; (2) the
intermuscular septa which separate it from the origins of the adjacent muscles; and
(3) the external lateral ligament of the elbow joint.
Insertion.-The back of the bases of the second and third metacarpal bones
near the lower part of their line of contact.
Structure. This muscle is thicker than the preceding, and its fibres have a
more decidedly penniform arrangement, as they pass from their long fibrous origin
obliquely downwards and forwards to the tendon which appears first upon the inner
border of the anterior aspect of the muscle about the middle, and is free at the
junction of the lower and middle thirds of the forearm. It passes through the
second compartment of the posterior annular ligament with the tendon of the pre-
ceding muscle. The tendons of this and the preceding muscle are invested in a
synovial sheath as they pass through the posterior annular ligament, and a small
bursa lies beneath each of them close to their insertions.
342
THE MUSCLES
Nerve-supply. From the posterior cord of the brachial plexus (through the
sixth and seventh cervical nerves) by filaments from the posterior interosseous
branch of the musculo-spiral nerve which enter the upper part of the anterior
surface of the muscle.
-
-
Action. (1) To extend the wrist; and (2) to feebly extend the elbow-joint.
Relations. It is covered by the extensor carpi radialis longior and the tendons
of the three thumb extensors. It lies upon the supinator brevis, the pronator
radii teres, the outer surface of the radius and the wrist joint.
Variations. Its muscular portion may be blended with that of the preceding muscle,
or slips may pass between the muscles. The tendon is often divided, and may send
separate insertions to the second and third metacarpal bones.
MUSCLES OF THE BACK OF THE FOREARM
The muscles upon the back of the forearm form two layers: the superficial,
consisting of those arising from the back of the external condyle of the humerus;
and the deep layer, of those which, with one exception, arise from the bones of the
forearm only.
The superficial layer continues upon the back of the forearm the series of the
radial extensors. It consists of four muscles: the extensor communis digitorum ;
the extensor minimi digiti; the extensor carpi ulnaris; and the anconeus.
SUPERFICIAL LAYER
1. EXTENSOR COMMUNIS DIGITORUM
The extensor communis digitorum-named from its common action upon the
four fingers-is fusiform and somewhat flattened, and divides below into four
tendons.
Origin. (1) The common tendon from the lower part of the external condyle;
(2) the deep fascia of the forearm; and (3) the intermuscular septa which separate
it from the extensor carpi radialis brevior, the extensor minimi digiti, and the
supinator brevis. 017340
Insertion. (1) The lateral ligaments of the metacarpo-phalangeal joints of
the four fingers; the back of the bases of (2) the second, and (3) the third
phalanges of the four fingers.
Structure. Arising from the interior of the aponeurotic case formed by the deep
fascia and the intermuscular septa, the fleshy fibres soon break up into separate
masses, and converge upon the four tendons which, beginning about the middle of
the forearm, become free a short distance above the wrist, and lie side by side in the
fourth compartment of the posterior annular ligament; those for the ring and little
fingers being more closely connected than the others. After their emergence at the
lower border of the ligament, the four tendons, which still retain their flattened
cylindrical shape, diverge to their respective fingers. Opposite the head of the meta-
carpal bones, each tendon gives off fibrous bands to the lateral ligaments of the
metacarpo-phalangeal joint. Upon the first phalanx the tendon expands into a
broad aponeurosis which fits closely by its concave anterior surface upon the back of
the bone and affords attachment by its lateral margins to other muscles. After
passing over the back of the first phalangeal joint, the central portion of this
aponeurosis is inserted into the base of the second phalanx, while its lateral

EXTENSOR COMMUNIS DIGITORUM
343
portions converge and, passing over the second phalangeal joint, are attached to the
back of the base of the ungual phalanx. A transverse band usually unites the
FIG. 277.-TENDONS UPON THE DORSUM OF THE HAND.

Extensor ossis metacarpi
pollicis
Extensor brevis pollicis
od 30
A
Posterior annular ligament
Extensor carpi ulnaris
Extensor carpi
radialis brevior
Extensor carpi
radialis longior
Extensor longus
pollicis
First dorsal
interosseous
Adductor
pollicis
Tendon of first dorsal
interosseous
Attachment of exten--
sor communis digi-
torum to second
phalanx
Attachment of exten--
sor communis digi-
torum to third pha-
lanx
Extensor communis
digitorum
Extensor minimi
digiti
Extensor indicis
tendons of the index and middle fingers above the heads of the metacarpal bones. A
stronger band passes downwards and outwards from the ring finger tendon to that
of the middle finger at the same level. The fourth tendon divides into two parts.

344
THE MUSCLES

The one joins with the tendon of the ring finger, which immediately afterwards
gives off a transverse band to the extensor tendon of the little finger, and the other
part joins the tendon of the extensor minimi digiti upon the metacarpal bone
of the little finger.
Nerve-supply. From the posterior cord of the brachial plexus (through
the seventh cervical nerve) by several branches from the posterior interosseous
division of the musculo-spiral nerve which enter the upper part of the deep surface
of the muscle.
Action.-(1) Chiefly to extend the first phalanges of the fingers. (2) It has
some power of extending the second and third phalanges; but this part of the
tendon of the muscle is chiefly under the control of the lumbricales and interossei,
which are attached to the sides of the expansion covering the first phalanx. After
extending the fingers, it will also (3) help in the extension of the wrist; and (4) to
a slight extent, of the elbow joint. The bands by which the tendons are attached
to one another upon the back of the hand hinder independent extension, especially
in the ring finger. The little and index fingers, having special extensors, do not
labour under this disadvantage.
Relations. Superficially, the deep fascia and posterior annular ligament;
deeply, the supinator brevis, the three extensors of the thumb, the extensor indicis,
the dorsal interossei, the posterior and anterior interosseous vessels, the posterior
interosseous nerve, the wrist and carpal joints; on the radial side is the extensor
carpi radialis brevior; and on the ulnar, the extensor minimi digiti.
Variations. Some of the tendons may be deficient, or more frequently the muscle
divides into more than four tendons, two or even three of which may be attached to
one finger. Occasionally a tendon joins that of the extensor longus pollicis.
2. EXTENSOR MINIMI DIGITI
The extensor minimi digiti-named from its action upon the little finger-is
small and fusiform.

-
Origin. (1) The common tendon from the back of the external condyle by a
long fibrous process; (2) the deep fascia; and (3) the intermuscular septa which
intervene between it and the adjacent muscles.
Insertion. With the corresponding tendon of the preceding muscle.
Structure-Arising from the interior of the elongated case formed by the
various aponeuroses which diverge from the back of the external condyle, the
fleshy fibres, which do not begin till some distance below that point, are inserted
into the radial border of a tendon which begins about the middle of the forearm,
and becomes free a short distance above the wrist joint, a little higher than that
of the corresponding part of the preceding muscle. Passing through the fifth
compartment of the posterior annular ligament, which lies upon the line of junction
of the radius and ulna, the tendon reaches the back of the fifth metacarpal bone, and
there blends with the fourth tendon of the extensor communis digitorum immediately
above the metacarpo-phalangeal joint.
Nerve-supply. From the posterior cord of the brachial plexus (through the
seventh cervical nerve), by a branch from the posterior interosseous division of the
musculo-spiral which enters the deep surface of the upper part of the muscle.
Action.-(1) To extend the first phalanx of the little finger; (2) to extend the
second and third phalanges; (3) to extend the wrist; and (4) very slightly the
elbow also.
Relations. Superficially, the deep fascia of the forearm and the posterior
annular ligament; deeply, the supinator brevis, the three extensors of the thumb,
and the extensor indicis, the inferior radio-ulnar joint, and the posterior inter-
EXTENSOR CARPI ULNARIS-ANCONE US
345
osseous artery. On the outer side lies the extensor communis digitorum; and on
the inner, the extensor carpi ulnaris.
Variations.--The extensor minimi digiti is rarely absent, but it is sometimes blended
with the preceding muscle. Its tendon is often divided, sometimes into as many as three
slips.
3. EXTENSOR CARPI ULNARIS
The extensor carpi ulnaris--named from its action upon the carpus and its
position on the ulnar border of the forearm-is a fusiform sheet.
Origin. By two heads. The first head: (1) By the common tendon from the
back of the external condyle; (2) the front of the deep fascia of the forearm; and
(3) the intermuscular septa which separate it from the extensor minimi digiti, the
anconeus, and the supinator brevis.
The second head: from the posterior border of the ulna, by the aponeurosis
common to it, the flexor carpi ulnaris, and the flexor profundus digitorum.
Insertion. The back of the base of the fifth metacarpal bone, close to its ulnar
border.
Structure. The fleshy fibres converge below upon the tendon of insertion,
which, beginning in the interior of the muscle in the middle of the forearm, soon
becomes visible upon the radial border of the back of the muscle. It receives fleshy
fibres in penniform fashion upon its ulnar border and deep surface nearly as far as
the wrist, where it enters the sixth compartment of the posterior annular ligament,
and lies in a special groove to the outer side of the styloid process of the ulna.
Nerve-supply. From the posterior cord of the brachial plexus (through the
eighth cervical nerve) by branches from the posterior interosseous division of the
musculo-spiral nerve which enter the deep surface of the muscle about the middle
of the forearm.
Action.-(1) To extend the wrist, acting upon the three articulations involved
in this movement; (2) to adduct the wrist, especially when the hand is pronated;
(3) it will also help in the extension of the elbow joint.
Relations. Superficially, the deep fascia of the forearm, and the posterior
annular ligament; deeply, the supinator brevis, three extensors of the thumb,
extensor indicis, posterior interosseous artery, the inner half of the posterior surface
of the ulna below the middle of the forearm, the wrist, and some carpal joints. On
the outer side lies the extensor minimi digiti; on the inner, the anconeus muscle.
Variations. Frequently a small slip of tendon passes downwards to join the tendon of
the preceding muscle, the first phalanx, or the head of the metacarpal bone. Occasionally
the fourth or even the third metacarpal bone may receive a slip.

4. ANCONEUS
The anconeus-named from its intimate relation with the elbow (aykov)-is a
triangular fan-shaped sheet.
Origin. (1) The lower part of the back of the external condyle; and (2) the
adjacent part of the posterior ligament of the elbow joint.
Insertion. The rough triangular impression upon the outer surface (1) of the
olecranon, and (2) of the upper third of the back of the ulna.
—
Structure. This muscle is a continuation downwards of the lower part of the
inner head of the triceps. Arising by a short tendon, which is prolonged upon the
deep surface of the muscle and along its outer border, the fleshy fibres diverge in
a fan shape, and are inserted either directly or by short tendinous fibres into the
346
THE MUSCLES
large special impression upon the ulna; the highest fibres being nearly horizontal,
and the lowest approaching more nearly to a vertical direction.
Nerve-supply. From the posterior cord of the brachial plexus (through the
seventh and eighth cervical nerves) by a long branch from the musculo-spiral nerve,
which, after passing through the inner head of the triceps muscle, enters the deep
aspect of the anconeus close to its upper border.
Action.-To extend the elbow, in association with the triceps, of which some
authors consider it to form a fourth head.
Relations. Superficially, the deep fascia of the forearm; deeply, the supinator
brevis, the posterior interosseous recurrent artery which runs through the deeper
fibres of the muscle, the elbow and upper radio-ulnar joints.
DEEP LAYER
The deep layer consists of five muscles: the supinator radii brevis; extensor
ossis metacarpi pollicis; extensor brevis pollicis; extensor longus pollicis; and the
extensor indicis. Four of these arise from the bones of the forearm, and one
only from the humerus also.
1. SUPINATOR RADII BREVIS
The supinator radii brevis-named from its action and size in comparison with
the brachio-radialis (=supinator longus)-is a rhomboidal sheet of muscular fibre
curved upon itself so as to form the greater part of a cylinder which wraps round the
upper third of the radius.
-
Origin. (1) Lower and back part of external condyle; (2) the external lateral
ligament of the elbow joint; (3) the orbicular ligament; (4) the triangular
depression below the lesser sigmoid cavity of the ulna, especially along its posterior
margin, which forms the upper part of the external border of the ulna.c
Insertion. (1) The back of the neck of the radius; (2) the anterior and outer
surfaces of the radius above and at the upper border of the oblique line.
Structure. Its origin is partly fleshy and partly by a strong aponeurosis which
covers the upper half of the muscle and gives attachment to some of the muscles in
the superficial sheet. The line of origin runs downwards and somewhat inwards
from the external condyle to the outer border of the ulna, while that of insertion
runs downwards and outwards from the tubercle of the radius to the impression
for the pronator radii teres.
Between these lines the fleshy fibres run in parallel curves wrapping round the
upper third of the radius. The muscle is divided into a small superficial and more
extensive deep plane by the posterior interosseous nerve which perforates it on its
way to supply the muscles at the back of the forearm. The line of insertion is
broken at the tubercle of the radius by a notch in which lies the bursa in front
of the attachment of the biceps tendon.
Nerve-supply. From the posterior cord of the brachial plexus (through the
sixth cervical nerve) by branches derived from the posterior interosseous division
of the musculo-spiral nerve, which are given off from this nerve as it perforates the
muscle.
Action.-To supinate the radius upon the ulna. By its contraction the muscle
unwraps itself from the radius; the tubercle of the radius is drawn forwards, and
the outer border of the bone backwards; and if the radius at the commencement
of action be in the position of complete pronation, it will be caused by this muscle
to revolve about the axis which passes through the centre of its head and the
middle of the lower extremity of the ulna through nearly 180°.



SUPINATOR RADII BREVIS
347
The action of this muscle will, unlike that of the biceps, be unaffected by the
position of the elbow.
This completes the list of muscles by which the rotation of the radius upon the
ulna is effected. The biceps and supinator brevis are the supinators; the pronator
FIG. 278.-THE DEEP LAYER OF THE BACK OF THE FOREARM.

inilog anga
Anconeus
Supinator brevis
Flexor carpi ulnaris
Extensor ossis metacarpi pollicis
Flexor profundus digitorum
Extensor brevis pollicis
Extensor longus pollicis.
Radial extensors-
Extensor indicis
Extensor carpi ulnaris
teres and quadratus the pronators. It should be remembered, however, that
ordinary pronation and supination are effected by a more complicated movement
than simple rotation of the radius, which would cause the hand to revolve around
the axis of the little finger. The usual rotation, the axis of which passes through
the line of the middle finger, involves a slight flexion and extension of the elbow
with some movement of the shoulder joint.
348
THE MUSCLES
Relations. Superficially, the biceps, brachio-radialis, pronator radii teres,
extensor carpi radialis brevior, extensor communis digitorum, extensor minimi
digiti, extensor carpi ulnaris, anconeus, the radial vessels and nerve, the posterior
interosseous recurrent artery; deeply, the superior radio-ulnar joint.
Variations. A second head has been seen from the humerus near the insertion of the
deltoid, and it may receive fibres from the brachio-radialis.
2. EXTENSOR OSSIS METACARPI POLLICIS
The extensor ossis metacarpi pollicis, or abductor longus pollicis-named from
its action upon the metacarpal bone of the thumb-is a fusiform sheet.
-
Origin. (1) The outer division of the posterior surface of the ulna for a short
distance below the junction of the upper and middle thirds of that bone; (2) the
adjacent portion of the interosseous membrane; (3) the posterior surface of the
radius near the middle of that bone for about two inches below the insertion of the
supinator brevis; and (4) the septa which separate it from the supinator brevis,
extensor carpi ulnaris, and extensor longus pollicis.
Insertion. (1) The small impression upon the radial side of the base of the first
metacarpal bone; (2) the fascia covering the ball of the thumb; and frequently
(3) the back of the trapezium.
Structure. A somewhat bipenniform muscular sheet arising by an origin which
stretches obliquely downwards and outwards from the back of the ulna, at the
upper part of its middle third, to the middle of the back of the radius. The tendon
appears first as an aponeurosis upon the anterior aspect of the muscle just below
the middle of the forearm. The fleshy fibres pass obliquely downwards and out-
wards to be inserted upon the posterior face of this aponeurosis. This as it descends
thickens into a rounded tendon, which, becoming free from its muscular fibres just
above the posterior annular ligament, crosses the back of the two radial extensor
tendons, and enters the first compartment of the posterior annular ligament upon
the outer surface of the lower end of the radius. After leaving this compartment,
the tendon passes vertically downwards, lying upon the external lateral ligament of
the wrist joint and the radial artery, to be inserted into the first metacarpal bone.
From its anterior border a strong aponeurosis is given off to that part of the palmar
fascia which covers the ball of the thumb, and which forms a part of the origin of
the abductor pollicis. Frequently this division of the insertion is indicated by a
groove running up the tendon, or by a more complete separation which may extend
as high as the fleshy fibres of the muscle.
Nerve-supply. From the posterior cord of the brachial plexus (through the
seventh cervical nerve) by filaments derived from the posterior interosseous division
of the musculo-spiral nerve which enter the muscle upon the upper part of its
superficial aspect.
Action. (1) It abducts and extends the first metacarpal bone, drawing the
thumb away from the middle line of the hand, and slightly forwards. (2) It abducts
the wrist. It should be remembered that on account of the plane of the thumb
being different to that of the palm and fingers, its abduction involves a considerable
forward movement, which must not be confounded with flexion.
Relations. Superficially, the extensor communis digitorum, extensor minimi
digiti, extensor carpi ulnaris, the posterior interosseous artery, and posterior
annular ligament; deeply, the extensor brevis and the extensor longus pollicis, the
two radial extensors, the radial artery, and the wrist joint.
Variations. The extensor ossis metacarpi pollicis may receive an accessory slip from
the radial group of extensors.

EXTENSOR BREVIS POLLICIS-EXTENSOR LONGUS POLLICIS 349
3. EXTENSOR BREVIS POLLICIS
The extensor brevis pollicis sometimes called the extensor primi internodii
pollicis, from its action upon the first phalanx (internodius) of the thumb-is flat
and fusiform.
Origin. (1) The middle of the posterior surface of the interosseous membrane
just below the preceding muscle; (2) an elongated impression upon the inner
part of the posterior surface of the radius extending from the middle of that bone
for about three inches downwards and slightly outwards; (3) an aponeurosis which
separates it from the preceding muscle.
Insertion. The back of the base of the first phalanx of the thumb.
Structure. A penniform muscle arising by short tendinous fibres. These soon
become fleshy, and pass downwards and outwards to a tendon which begins in the
lower third of the forearm upon the radial border of its superficial aspect. Lying
beneath the tendon of the preceding muscle and in close connection with it, this
tendon passes over the tendons of the radial extensors, runs through the first
compartment of the posterior annular ligament, crosses the first metacarpo-
phalangeal joint on the ulnar side of the tendon of the preceding muscle, and
then expands into a broad aponeurosis which is inserted into the whole of the
posterior surface of the base of the first phalanx.
Nerve-supply. From the posterior cord of the brachial plexus (through the
seventh cervical nerve) by a branch from the posterior interosseous division of the
musculo-spiral nerve, which enters the upper part of the muscle on the ulnar
border of its superficial aspect.
Action. It is a feeble muscle, the chief function of which is (1) to extend the
metacarpo-phalangeal joint of the thumb; at the same time it will assist the
extensor ossis metacarpi pollicis in (2) abducting and extending the first metacarpal
bone; and afterwards it will assist in (3) the abduction of the wrist.
Relations. Superficially, the extensor ossis metacarpi pollicis, extensor com-
munis digitorum, extensor minimi digiti, and posterior annular ligament; deeply,
the radial extensors, the radial artery, the wrist and first metacarpo-phalangeal
joints.
Variations. The extensor brevis pollicis may be absent, or it may be blended with
the preceding muscle. It may have insertions upon the metacarpal bones or the last
phalanx. An accessory slip has been observed from the external condylar ridge of the
humerus.


4. EXTENSOR LONGUS POLLICIS
The extensor longus pollicis, or extensor secundi internodii pollicis-named
from its action and length-is flat and fusiform.
Origin. (1) An elongated impression upon the outer part of the posterior surface
of the ulna, extending from the middle of that bone for three or four inches down-
wards and slightly outwards close to its external border. (2) The adjacent part of
the back of the interosseous membrane, and a septum between it and the extensor
indicis.
Insertion. The back of the base of the last phalanx of the thumb.
Structure. This muscle, which is stronger than the preceding, has also a
penniform arrangement. Its fibres pass downwards and outwards from their fleshy
origin to be inserted into the tendon upon the back of the muscle, which, appearing
about two inches from its upper extremity near its radial border, gradually
thickens as it passes obliquely downwards and outwards. Becoming free from
muscular fibres at the upper border of the posterior annular ligament, it enters the
350
THE MUSCLES
deep groove which forms the third compartment beneath that ligament. At the
lower extremity of this canal it crosses obliquely the two radial extensor tendons
at the back of the wrist joint, and upon the back of the first metacarpal bone it lies
in close contact with the inner border of the tendon of the preceding muscle, and
expands into a flat and broad aponeurosis which covers the back of the first
phalanx before its insertion into the last phalanx. Whilst spread over the convex
surface of the shaft of the first phalanx, it receives small tendinous insertions from
the abductor and adductor muscles of the ball of the thumb.
The three tendons of the extensor muscles of the thumb enclose a triangular
space which is visible upon the outer side of the wrist joint, and is bounded by the
tendons of the extensor ossis metacarpi pollicis and the extensor brevis pollicis
upon its radial side, by the tendon of the extensor longus pollicis upon its ulnar
side, and above by the lower end of the radius. Across this triangle stretches the
radial artery, in its passage beneath the tendons from the anterior surface of the
wrist to the upper part of the back of the first interosseous space.
-
Nerve-supply. From the posterior cord of the brachial plexus (through the
seventh cervical nerve), by branches from the posterior interosseous division of the
musculo-spiral nerve which enter the upper part of the muscle upon its superficial
aspect.
Action. It is (1) a strong extensor of the second phalangeal joint of the thumb;
and afterwards (2) of the first phalanx. It will (3) extend, and at the same time
adduct, the first metacarpal bone so as to draw the whole thumb in the extended
position backwards, and at the same time inwards. It will also (4) assist in the
extension of the wrist, and (5) in the supination of the forearm.
Relations. Superficially, the extensor ossis metacarpi pollicis, extensor com-
munis digitorum, extensor minimi digiti, extensor carpi ulnaris, posterior inter-
osseous artery, and posterior annular ligament; deeply, the radial extensors, the
radial artery, wrist, metacarpo-phalangeal, and phalangeal joints.
Variations. This muscle may send a slip to the base of the first phalanx of the thumb.
It may also receive a tendinous slip from the following muscle.
5. EXTENSOR INDICIS
The extensor indicis-named from its action upon the index finger-is flat and
fusiform.
Origin. (1) An elongated impression which stretches downwards and slightly
outwards from the junction of the middle and lower thirds of the outer division of
the posterior surface of the ulna, immediately internal to the impression for the
preceding muscle, but at the same time rather lower down, to within about an inch
of the lower extremity of that bone. (2) For a short space from the part of the
interosseous ligament which is adjacent to the lower part of this impression.
(3) The septum between it and the preceding muscle.
Insertion. The inner side of the aponeurosis of the first tendon of the extensor
communis digitorum.
Structure. This penniform muscle arises by fleshy fibres which pass obliquely
downwards and outwards to the anterior surface of a tendon which is first seen
upon the radial border of its posterior surface in the lower third of the forearm, and,
becoming free just above the wrist, passes beneath the tendon of the extensor
minimi digiti, and enters the fourth compartment of the posterior annular ligament,
where it lies beneath the inner tendons of the extensor communis digitorum.
It is then inserted into the inner edge of the aponeurosis of the tendon of the
common extensor belonging to the index finger, at about the level of the metacarpo-
phalangeal joint.

THE PALMAR FASCIA
351
Nerve-supply. From the posterior cord of the brachial plexus (through the
seventh cervical nerve), by a branch from the posterior interosseous division of the
musculo-spiral nerve which enters the upper part of the muscle near the radial
border of its superficial aspect.
Action. It assists the extensor communis digitorum in (1) extending the index
finger, and especially its first phalanx. At the same time, on account of its
direction, it will (2) adduct the index finger, while the action of the extensor
communis digitorum upon this finger is that of extension combined with abduction.
It will then assist feebly in (3) the extension of the wrist.
Relations. Superficially, the extensor communis digitorum, the extensor
minimi digiti, extensor carpi ulnaris, and posterior annular ligament. Deeply,
the dorsal interosseous muscle of the second space, the wrist, and some carpal
joints.
Variations. The extensor indicis may give slips to the extensor longus pollicis and to
the middle finger. It may receive slips from the posterior carpal ligaments or the bases of
the metacarpal bones, and these slips may be inserted into several digits, so as to form an
extensor brevis digitorum manus.
THE FASCLE OF THE HAND

The dorsal fascia is a thin layer, continuous with the posterior annular ligament,
and, like it, composed chiefly of transverse fibres. It covers the extensor tendons,
and connects them together upon the back of the hand; and upon the first phalanges
it blends with the aponeuroses which succeed to the tendons. Between the fingers
it dips down to join the superficial transverse ligament which forms the web by
which the bases of the fingers are connected.
A deeper layer of the dorsal fascia covers the back of the dorsal interossei, and
is attached to the back of the metacarpal bones.
THE PALMAR FASCIA
The palmar fascia takes the place of the deep fascia in the palm of the hand,
and is for the most part formed by the expansion of the tendon of the palmaris
longus. It is also continuous with the lower margin of the anterior annular liga-
ment; it may be divided into a central and two lateral portions. The central division,
which is by far the strongest, is of a triangular shape, the apex being continuous
with the tendon of the palmaris longus, and also attached to the lower border of
the anterior annular ligament; the base corresponding to the heads of the four
inner metacarpal bones. It consists in front of longitudinally arranged bundles of
fibrous tissue derived from the palmaris longus tendon, and behind of transverse
fibres which continue those of the annular ligament. Below, the fascia divides into
four processes which join the ligamenta vaginalia of the finger tendons. Each of
these four processes forms a bridge across the tendons, and is inserted, at the sides
of the metacarpo-phalangeal joint, into the lateral and the deep transverse ligaments.
This strong central portion of the palmar fascia is closely connected upon its anterior
surface with the skin by fibrous septa, which form small compartments in which
are lodged pellets of the subcutaneous fat. Upon its posterior surface it is smooth
and in contact with the synovial membrane of the great palmar bursa above, and
of the thecæ below. Between its four processes there are three spaces left through
which the digital nerves and arteries emerge. These are bridged over by transverse
fibres which connect the processes, and which form the superficial transverse
ligaments lying in the webs between the fingers.


352
THE MUSCLES
The outer division, or thenar fascia, is that portion of the palmar fascia which
covers the ball of the thumb. It is connected above with the anterior annular
ligament, the tendon of the palmaris longus, and an aponeurosis from the tendon.
of the extensor ossis metacarpi pollicis. After covering the short muscles of the
thumb, it is continuous below with the ligamentum vaginale of the flexor longus
pollicis tendon. The inner division, or hypothenar fascia, is of a triangular shape,
the base being above and the apex below. Arising from the anterior annular
ligament and the deep fascia of the forearm at the inner side of the wrist, it
invests the short palmar muscles peculiar to the little finger, and terminates upon
the ulnar border of the hand close to the fifth metacarpo-phalangeal joint. It is
covered above by the palmaris brevis.
A deep layer of fascia covers the front of the interossei muscles, and is attached
by thin longitudinal septa to the posterior surface of the central part of the palmar
fascia.
The ligamenta vaginalia are strong bands of transverse fibres which are
attached chiefly to the borders of the first and second phalanges, and serve to
bind in their place the long flexor tendons. Opposite the joints the ligaments
are thin, and composed chiefly of obliquely decussating fibres.
The sheaths of the flexor tendons, or thecæ as they are called, are blind tubes
of synovial membrane which invest the back of the ligamenta vaginalia and the
front of the three phalanges and the interphalangeal joints. They extend from
the metacarpo-phalangeal joint to the middle of the last phalanx; and at the
extremities of the tube the synovial membrane is reflected upon the surface of the
flexor tendons. Small folds and cords containing connective tissue and blood-
vessels, and invested by the synovial membrane, stretch across the intervening
space. These are called vincula accessoria (fig. 279). One set of these, the
ligamenta brevia, are of triangular shape, and pass directly forwards from the
front of the lower part of the first and second phalanges to the back of the
overlying tendons; while the other set-which are called the ligamenta longa-
are small cords running downwards and somewhat forwards from the phalanges
to the tendons, at a higher level than the ligamenta brevia. The compartment
of the palmar bursa belonging to the flexor longus pollicis tendon is continuous
with the theca of the thumb. The theca also of the little finger is close to, and
frequently in communication with, the lower part of the great palmar bursa upon
its ulnar side (fig. 274).

MUSCLES OF THE HAND
The muscles of the hand proper consist :-first, of a superficial one, which lies
upon the palmar fascia; and, secondly, of a deeper set, which may be divided into a
central group belonging to the fingers generally, and two other groups, which are
associated with the thumb on the radial, and the little finger on the ulnar side of
the palm.
SUPERFICIAL MUSCLE OF THE HAND
PALMARIS BREVIS
The palmaris brevis (fig. 280)-named from its position in the palm of the
hand, and its small size-is a small quadrilateral sheet.
Origin. (1) The front of the lower part of the anterior annular ligament about

—

PALMARIS BREVIS
353
its middle; and (2) the adjacent part of the palmar fascia at the inner edge of its
great central division.
Insertion. The deep surface of the skin and the subcutaneous fat, along the
ulnar border of the upper part of the palm.
Structure.-Arising by fleshy and short tendinous fibres, this muscle passes in
transverse fasciculi to its insertion, which is of a similar character to its origin.
It belongs to that type of muscle of which the panniculus carnosus in the
FIG. 279.-DIAGRAM OF A VERTICAL SECTION THROUGH THE MIDDLE OF THE HAND.
Posterior annular ligament
-Great palmar bursa
-Anterior annular ligament
Home quel
Deep transverse ligament
Attachment of common
extensor to first pha-
lanx
Superficial transverse
ligament
Dorsal interosseous
Lumbricalis
Palmar fascia
Flexor profundus digitorum
Flexor sublimis digitorum
Theca
Vincula accessoria
Attachment of common
extensor to second
phalanx
Attachment of common
extensor to third pha-
lanx
Indy blth ben
viqque-ovisk
Ligamentum vaginale
Vincula accessoria A
lower animals is the best example, and lies in the subcutaneous tissue superficial
to the deep fascia like the platysma myoides and the superficial muscles of the
face.
Nerve-supply. From the inner cord of the brachial plexus (through the first
thoracic nerve), by filaments from the superficial division of the ulnar nerve which
enter the muscle upon its deep aspect near its upper border.
Action. It draws the skin and the superficial fascia of the ulnar border of the
A A

354
THE MUSCLES
hand towards the middle line of the palm, forming a deep dimple or groove upon
the upper part of the ulnar border of the hand, and at the same time raising
the soft parts into a prominent vertical ridge, the object of which appears to be
to prevent the ulnar nerve and artery from being pressed upon when a hard
substance is grasped by the hand. It also helps to deepen the cup-shaped hollow
when the palm is used to convey fluid to the mouth.
Relations. Superficially, the skin; deeply, the hypothenar fascia, which
separates it from the abductor and flexor brevis minimi digiti, the ulnar vessels
and nerve.
Variations. This muscle may be entirely absent.
DEEP MUSCLES OF THE PALM OF THE HAND
CENTRAL GROUP
Consisting of two sets of muscles-the lumbricales and the interossei.
1. THE LUMBRICALES

The lumbricales-named from their resemblance to earth-worms (= lumbrici)
-are four small muscles of a fusiform shape.
Origin. The two outer ones from the outer side of the first and second tendons
of the flexor profundus digitorum; the two inner from the adjacent sides of the
second and third, and third and fourth tendons of the flexor profundus digitorum
respectively. All four are attached to the palmar aspect of the deep flexor, and the
origin begins at the lower border of the anterior annular ligament.
Insertion. The aponeurosis of the extensor communis digitorum tendon on the
radial side of the first phalanx of each of the four fingers.
Structure. -Arising fleshy from the tendons of the deep flexor, the fibres con-
verge upon a small tendon which becomes free a short distance above the metacarpo-
phalangeal joint. The tendon passes in front of the deep transverse metacarpal
ligament, below which it expands, and is attached to the border of the extensor
tendon.
Nerve-supply. From the outer and inner cords of the brachial plexus; the
first and second receiving small filaments from the digital branches of the median
nerve, which enter the muscle near the radial border in the middle third of their
palmar aspect. The third and fourth lumbricales are supplied by filaments of
the deep branch of the ulnar nerve, which enter their respective muscles in the
middle third of their deep surfaces.
Action. Their chief action will be (1) to flex the first phalanges upon the meta-
carpal bones; and at the same time (2) to extend the second and third phalanges
by their traction upon the sides of the extensor aponeurosis which covers the back
of each of the first phalanges. In this action they assist the interosseous muscles;
but the lumbricales have this advantage over them, that when the second and third
phalanges are flexed by the flexor sublimis and profundus, the lumbricales will flex
the first phalanges with increased force, inasmuch as the tendons from which they
arise have been retracted, whereas the origins of the interossei are practically fixed.
The first and second lumbricales will act feebly as abductors of the index and middle
fingers; the third and fourth as adductors of the ring and little fingers. They will
also have some influence, together with the interossei, upon the aponeuroses of the
extensor communis digitorum tendons in binding them down upon the first
THE LUMBRICALES
355
phalanges. In this way they perform for the dorsal tendon a similar function
to that which is exercised by the ligamentum vaginale upon the two palmar
tendons.
FIG. 280.-THE SUPERFICIAL MUSCLES OF THE PALM OF THE HAND.

Flexor carpi
ulnaris
Anterior annular
ligament
Palmaris longus
Palmaris brevis
Abductor minimi
digiti
Flexor brevis
minimi digiti
Flexor sublimis
digitorum
Flexor carpi radialis
Extensor ossis metacarpi pollicis
Opponens pollicis
-Abductor pollicis
Flexor brevis pollicis
Adductor pollicis
First lumbri-
calis
First dorsal
interosseous
Ligamentum
vaginale
Ligamentum vaginale
Flexor sublimis digitorum
Tendon of
flexor
profundus
Flexor profundus digitorum
Flexor
sublimis
digitorum
Flexor profundus
digitorum
19170
Relations. Superficially, the tendons of the flexor sublimis digitorum and
the superficial transverse ligaments; deeply, the interossèi muscles, the adductor
and part of the flexor brevis pollicis, and the deep transverse ligaments; on the
ulnar side their tendons are in contact with the metacarpo-phalangeal joints.
AA2

356
THE MUSCLES
Variations. The fourth lumbricalis is sometimes absent. They may vary in their
origins, sometimes arising from one, and sometimes from two adjacent tendons. Occa-
sionally one may arise from the flexor longus pollicis tendon. They may be inserted into
the ulnar side of a finger, or into the adjacent sides of two fingers.
2. THE INTEROSSEI
The interossei--named from their position between the metacarpal bones-are
seven in number, three being palmar and four dorsal. They are small muscles, of
penniform or bipenniform structure. Both sets are easily exposed to view by a
deep dissection in the palm, but the dorsal set is alone visible in the back of the
hand.
FIG. 281.-THE PALMAR INTEROSSEI.
The three palmar interossei are fusiform in shape.
Origin.
They arise from the sides of the metacarpal bones: the first occupy-
ing the whole of the ulnar side of the second metacarpal bone; the second, the
radial side of the fourth metacarpal bone; the third, the radial side of the fifth
metacarpal bone.
Insertion.- By small tendons (1) into the aponeuroses of the extensor tendons
upon the back of the first phalanges of the index, ring, and little fingers; and (2)
the adjacent portion of the side of each first phalanx near to its base; the first
being attached to the ulnar border, and the second and third to the radial borders
of their fingers.
Structure.-Fleshy fibres arising along the whole length of the metacarpal
bone are inserted in penniform fashion upon the tendon, which, beginning on the
unattached border of the muscle near the middle of the interosseous space, becomes
free just above the metacarpo-phalangeal joint, and passes beneath the deep
transverse ligament which separates it from the tendon of the lumbricalis muscle.

THE INTEROSSEI
357
At this place a small bursa separates the tendon from the deep transverse
ligament, and the lateral ligament of the metacarpo-phalangeal joint. do dand
Nerve-supply. From the inner cord of the brachial plexus (through the
eighth cervical nerve), by small filaments which, coming from the deep branch of
the ulnar nerve, pass into the upper part of the muscles upon their anterior aspect.
Action and relations.-Vide infra.
Of the four dorsal interossei, the first forms a thick triangular sheet, while the
other three are fusiform and prismatic.
Origin.-From the five metacarpal bones, each muscle arising from the adjacent
surfaces of the two bones bounding an interosseous space. begab mizah
Insertion. (1) Into the sides of the aponeuroses of the extensor communis
digitorum tendons; and (2) the adjacent parts of the first phalanges.
Structure. The fleshy fibres arise from the adjacent surfaces of the metacarpal

FIG. 282. THE DORSAL INTEROSSEI.
adi blod
bond radio
bones in bipenniform fashion, and converge upon a tendon which, beginning about
the middle of the interosseous space, becomes free just above the metacarpo-
phalangeal joint, and then passes beneath the deep transverse ligament to its
insertion into the side of the aponeurosis, and into the upper part of the border of
the first phalanx. 25
The first muscle is thick and by far the strongest, and forms with the adductor
pollicis the fleshy web which fills the interval between the metacarpal bones of the
thumb and the index finger. Its origin from the first metacarpal bone occupies
the upper half of that bone, while that from the second is more extensive. It is
inserted into the radial side of the aponeurosis upon the back of the first phalanx
as well as into the upper part of the outer border of that bone. The second is
inserted into the radial side of the aponeurosis upon the first phalanx of the
middle finger and into the adjacent bone. The third into the ulnar side of the
aponeurosis upon the back of the first phalanx of the middle finger and into

358
THE MUSCLES

the adjacent bone. The fourth into the ulnar side of the aponeurosis upon the
back of the ring finger and the adjacent bone. Of the two heads of each of these
muscles, the one arising from the metacarpal bone of the finger into which the
muscle is inserted, is always the larger.
Nerve-supply. From the inner cord of the brachial plexus (through the
eighth cervical nerve), by branches from the deep division of the ulnar nerve which
enter the muscles at the upper part of their anterior aspect.
Action of the interossei muscles. Firstly, the common action of all the interossei
is (1) to flex the first phalanges; and (2) to extend the second and third. Their
power of flexion depends upon their insertion into the sides of the first phalanges
as well as the edges of the aponeuroses by which the backs of these phalanges are
covered. The extension of the second and third phalanges depends upon the fact
that the portion of the aponeurosis into which each of them is inserted is continued
downwards to the bases of these phalanges. A good example of the action of these
muscles and of the lumbricales is given in the movements of the fingers which
hold the pen in writing. In forming the light upstroke it will be seen that flexion
of the first, accompanies the extension of the second and third phalanges. This
movement is due to the contraction of the lumbricales and interossei. On the
other hand, the thick downstroke is formed by the extension of the first, and the
flexion of the second and third phalanges; this strong movement being due to the
action of three powerful muscles, the extensor communis, the flexor sublimis,
and the flexor profundus digitorum. Secondly, the palmar interossei adduct the
index, ring and little finger towards the middle line of the hand which passes
through the middle finger. Thirdly, the dorsal interossei abduct the index, middle
and ring fingers from the middle line of the hand. As the middle finger can be
drawn either to the radial or ulnar side from the middle line of the hand, it has
two dorsal interossei to abduct it. The first dorsal interosseous muscle will also
assist in adducting the thumb.
Relations. On the palmar surface of the interossei, separated from them by
the deep layer of fascia, lie the flexor profundus digitorum tendons and the lumbri-
cales, the adductor and part of the short flexor of the thumb, the deep palmar
arch above, and the deep transverse ligaments below; behind, lie the tendons of
the extensor communis digitorum and extensor indicis, separated from the dorsal
interossei by the deep dorsal fascia.
Variations. Sometimes the dorsal interossei receive small accessory heads from the
posterior carpal ligaments, the lower end of the radius, or the adjacent deep fascia. A
part of the first dorsal interosseous has been seen running separately from the front of the
metacarpo-phalangeal joint of the thumb to the tendon of the first lumbricalis. Occa-
sionally the second dorsal interosseous is inserted upon the ulnar side of the index finger,
so as to resemble the same muscle in the foot.

MUSCLES OF THE THENAR EMINENCE

These are four in number, and they form a fleshy mass at the radial border of
the palm, covered by the thenar portion of the palmar fascia, and called the
thenar eminence or ball of the thumb. They are the abductor pollicis, the
opponens pollicis, the flexor brevis pollicis, and the adductor pollicis.
1. ABDUCTOR POLLICIS
The abductor pollicis-named from its action upon the thumb-is a small thick
triangular sheet.
Origin. (1) The tuberosity of the scaphoid bone; (2) the upper part of the


ABDUCTOR POLLICIS
359
008
ridge on the trapezium; (3) the outer part of the front of the anterior annular
ligament; (4) the outer or thenar division of the palmar fascia by which the ball
of the thumb is covered; and (5) the slip from the tendon of the extensor ossis
metacarpi pollicis which joins this part of the palmar fascia.
Insertion. (1) With the outer tendon of the flexor brevis pollicis into the
FIG. 283.-THE DEEPER MUSCLES OF THE PALM OF THE HAND.

Flexor carpi
ulnaris
Abductor
minimi digiti
Flexor sublimis.
digitorum
Flexor brevis-
minimi digiti
Extensor ossis metacarpi
pollicis
Flexor carpi radialis
Extensor brevis pollicis
Abductor pollicis
Opponens pollicis
Flexor profun-.
dus digitorum
I um-
bricales
First
dorsal
inter-
osseous
Abductor
pollicis
Flexor
brevis
pollicis
Adductor
pollicis
radial side of the base of the first phalanx of the thumb; and into (2) the outer
edge of the aponeurosis of the extensor longus pollicis upon the back of the first
phalanx.
Structure.- Arising by fleshy or short tendinous fibres, the muscle converges
upon a short tendon which blends with the adjacent tendon of the flexor brevis.
Nerve-supply. From the outer and inner cords of the brachial plexus (through
the sixth cervical nerve), by a branch from the palmar division of the median
nerve, which, after passing under the anterior annular ligament, goes upwards and
360
THE MUSCLES
outwards to enter the upper part of the deep aspect of the muscle near its ulnar
border.
Action (1) To abduct, and (2) to flex the first phalanx of the thumb. As the
bones of the thumb are in a different plane to those of the fingers, this movement
will draw the thumb forwards and at the same time slightly inwards. By its
insertion into the aponeurosis of the extensor longus pollicis, this muscle will help
(3) to extend the last phalanx of the thumb.
Relations. Superficially, the thenar fascia, and the superficialis volæ artery,
which usually perforates the muscle; deeply, the outer head of the flexor brevis
pollicis and the opponens pollicis.
Variations. As already mentioned, it receives occasional slips from the radial extensors
of the carpus and the extensor ossis metacarpi pollicis. It frequently receives a thin
muscular slip from the skin over the trapezium; it may also be supplemented by the
opponens pollicis or a small slip from the styloid process of the radius.
2. OPPONENS POLLICIS

The opponens pollicis, or flexor ossis metacarpi pollicis, is named from its
action, as it helps in opposing the thumb to the other fingers and at the same time
is a flexor of the first metacarpal bone. It is a short, thick, triangular sheet.
Origin. (1) The front of the ridge on the trapezium below the preceding; and
(2) the outer half of the lower border of the anterior annular ligament.
Insertion. The whole of the outer border of the anterior surface of the shaft
of the first metacarpal bone.
Structure.-Arising by a short tendinous or fleshy origin, the muscular fibres
diverge fanwise to their insertion. The lower border of the muscle is often so
blended with the outer head of the next muscle that the separation is somewhat
artificial.
Nerve-supply. From the same source as the preceding; the filaments entering
the anterior surface of the muscle near to the upper part of its ulnar border.
Action.-To flex the first metacarpal bone, which it draws forwards and
inwards. This movement, on account of the shape of the carpo-metacarpal joint,
is accompanied by a certain amount of rotation inwards, by which the palmar
aspect of the thumb is made to look backwards and inwards.
Relations. Superficially, the abductor pollicis and the thenar fascia; deeply,
and upon its ulnar border, the flexor brevis pollicis. It also lies upon the joint
between the metacarpal bone and the trapezium.

3. FLEXOR BREVIS POLLICIS
The flexor brevis pollicis-named from its action and short length in compari-
son with the long flexor-consists of two heads: each forming a flat triangular
sheet.
Origin. The outer head arises from (1) the outer two-thirds of the lower border
of the anterior annular ligament; (2) the lower part of the ridge of the trape-
zium. The inner head, from (1) the front of the os magnum; (2) the front of the
bases of the first, second, and third metacarpal bones; and (3) from the front of
the sheath of the flexor carpi radialis tendon.
Insertion. The outer and inner sides of the front of the base of the first phalanx
of the thumb.
Structure.-Arising by short tendinous as well as by fleshy fibres, the two heads
become tendinous a short distance above the first metacarpo-phalangeal joint, and
have imbedded in their substance sesamoid bones of a somewhat hemispherical shape,

FLEXOR BREVIS POLLICIS
361
and about one-sixth of an inch in diameter, which rest by small articular facets
covered with cartilage upon the palmar aspect of the condyles of the first metacarpal
bone. Close to their insertion the tendinous fibres are blended with those of the
abductor pollicis externally, and the adductor internally. In the inner head three
distinct divisions may generally be observed. The first or outermost division is a
small fusiform slip which passes beneath the tendon of the flexor longus pollicis to
join the outer head, and to be inserted into the radial sesamoid bone. The second
division is fan-shaped, and its fibres, which form the greater part of the inner head,
converge to embrace the ulnar sesamoid bone. The third division lies under cover
FIG. 284. THE PRONATOR QUADRATUS AND DEEP VIEW OF THE PALM.

Flexor
carpi
ulnaris
Abductor
minimi
Marie digiti
Opponens
minimi
digiti
Flexor
brevis
minimi
digiti
Third
palmar
interosseous
Fourth
dorsal
interosseous
Pronator quadratus
Abductor pollicis
Outer head of flexor
brevis pollicis
Inner head of
flexor brevis
pollicis (first
division)
Opponens pollicis
Inner head of
flexor brevis
pollicis (third
division)
Inner head of
flexor brevis
pollicis (second
division)
-Adductor pollicis
Second palmar interosseous
First palmar interosseous
Third dorsal interosseous
Second dorsal interosseous
-Dorsal inter-
osseous
of the second. It is a small fleshy slip, which arises from the ulnar side of the
base of the first metacarpal bone, and passes downwards to be inserted with the
adductor pollicis into the ulnar side of the base of the first phalanx. Some authors
describe this third division as the inner head of the flexor brevis pollicis, and the
first and second divisions as the adductor pollicis obliquus.
Nerve-supply. The outer head is supplied (through the sixth cervical nerve)
by the palmar branch of the median, which enters the middle of its anterior
surface near its ulnar border. The inner head is supplied (through the eighth
cervical nerve) by the deep branch of the ulnar nerve which enters the upper part
of its deep surface close to its ulnar border.
362
THE MUSCLES
Action.-Both heads will flex the metacarpo-phalangeal joint of the thumb. The
outer head will flex also the carpo-metacarpal joint, while the inner head will be
an adductor as well as flexor of this joint. The former will act in association
with the abductor and opponens, and will draw the thumb forwards and inwards,
keeping it at some distance from the palm of the hand. The latter will act with
the adductor, and draw it more directly inwards in close proximity to the palm of
the hand.
Relations. The outer head lies beneath the abductor pollicis, and in contact
by its radial border with the opponens pollicis. The inner head is partly separated
from it by the tendon of the flexor longus pollicis; upon its ulnar border it is in
contact with the adductor. In front of it lie the tendons of the flexor profundus
with the outer lumbricales; behind, are the third part of the radial artery and the
interossei muscles of the first two spaces.
4. ADDUCTOR POLLICIS
The adductor pollicis, sometimes called the adductor pollicis transversus-
named from its action-is a thick triangular sheet.
Origin. The front border of the shaft of the third metacarpal bone.
Insertion. (1) The inner side of the base of the first phalanx of the thumb;
(2) the inner side of the aponeurosis of the extensor longus pollicis which covers
the first phalanx.
Structure.-Arising by short tendinous or fleshy fibres, the muscle converges
upon a short tendon, which blends on its outer side with the inner tendon of the
flexor brevis pollicis, and sends a fibrous slip to the inner side of the aponeurosis
of the extensor longus pollicis.
Nerve-supply. From the lower cord of the brachial plexus (through the eighth
cervical nerve), by the deep branch of the ulnar which sends filaments to the
upper border and deep surface near the origin.
Action.-(1) To flex the first phalanx of the thumb; (2) to adduct and flex
the carpo-metacarpal joint of the thumb; (3) to extend the second phalanx of the
thumb. This latter action of the adductor and abductor pollicis is useful in many
of the movements of the thumb, in which it will be found that the second phalanx
has to be kept extended, while its palmar aspect is being opposed to the tips of
the other digits.

-
Relations. Superficially, some of the tendons of the flexor profundus digitorum
and the two outer lumbricales; deeply, the abductor indicis and the interossei of
the space between the second and third metacarpal bones. Part of the lower
border is subcutaneous.
Variations. The adductor pollicis is often difficult to separate from the inner head of
the flexor brevis pollicis, the adductor obliquus, as it is sometimes called.
brooos bine
yiggaz av

ABDUCTOR AND FLEXOR BREVIS MINIMI DIGITI 363
MUSCLES OF THE HYPOTHENAR EMINENCE
These are three in number-the abductor minimi digiti, the opponens minimi
digiti, and the flexor brevis minimi digiti. They lie under cover of the thin internal
division of the palmar fascia.
1. ABDUCTOR MINIMI DIGITI
The abductor minimi digiti-named from its action-is fusiform and some-
what flattened.
Origin.-(1) The lower half of the pisiform bone; (2) the continuation of the
tendon of the flexor carpi ulnaris below this bone.
Insertion. (1) The ulnar side of the base of the first phalanx of the little
finger; and (2) the adjacent portion of the aponeurosis of the extensor minimi
digiti.
Structure.-Arising by short tendinous fibres, it soon forms a flat fleshy mass
which contracts slightly below, and just before its insertion, having again become
tendinous, it is for the most part attached to the first phalanx, but it also sends a
small slip backwards to the extensor aponeurosis.
Nerve-supply. From the ulnar nerve through the eighth cervical nerve. It
receives small filaments at the outer and deep aspect, usually from the deep palmar
division of the ulnar nerve.
Action. To abduct, and at the same time flex, the metacarpo-phalangeal joint
of the little finger; it will also assist, like an interosseous muscle, in the extension
of the second and third phalanges.
Relations. Superficially, the hypothenar part of the palmar fascia and the
palmaris brevis; deeply, the flexor brevis and opponens minimi digiti. Upon its
radial border are placed the deep palmar branches of the ulnar artery and nerve.

2. FLEXOR BREVIS MINIMI DIGITI
The flexor brevis minimi digiti-named from its action-is small and fusiform.
Origin. (1) The ulnar surface of the hook of the unciform bone; (2) the
adjacent part of the front of the anterior annular ligament.
Insertion. The ulnar side of the base of the first phalanx of the little finger.
Structure.--Its origin and insertion are by short tendinous fibres, and the rest
of the muscle is fleshy.
Nerve-supply. Through the eighth cervical nerve, from the deep branch of the
ulnar nerve which sends filaments to the upper part of its deep and ulnar surface.
Action.-To flex the first phalanx of the little finger.
Relations. Superficially, the hypothenar part of the palmar fascia, the lower
part of the abductor minimi digiti, and the superficial palmar arch; deeply, the
opponens minimi digiti and the fifth metacarpal bone; and to its radial side lie
the flexor tendons of the little finger. This muscle is closely connected with the
previous one, from which it is separated above by the deep palmar branches of
the ulnar artery and nerve.
Variations. It may fail, or be blended with the abductor or opponens minimi digiti. An
accessory slip may come to it from the lower third of the ulna at its inner border, from
the tendon of the flexor carpi ulnaris, or the deep fascia of the forearm.

364
THE MUSCLES

3. OPPONENS MINIMI DIGITI
The opponens minimi digiti (= flexor ossis metacarpi minimi digiti)-named
from its action-is a triangular fan-shaped sheet.
Origin. (1) From the hook of the unciform bone deeper than the preceding;
(2) from the adjacent part of the anterior annular ligament.
Insertion. The whole of the ulnar border and part of the head of the fifth
metacarpal bone.
Structure.-Arising by short tendinous fibres, the fleshy bundles diverge down-
wards and outwards, and are inserted by short tendinous fibres.
Nerve-supply. Through the eighth cervical nerve, from the deep branch of the
ulnar nerve which sends filaments to the upper part of its ulnar aspect.
Action.-To flex the fifth metacarpal bone, and at the same time slightly to
adduct it. This movement is observed when the palm is cupped, as when the
hand is used as a scoop to lift water to the mouth.
Relations. Superficially, the abductor and the flexor brevis minimi digiti; and
deeply, the interossei of the fourth interspace, and the deep branches of the ulnar
artery and nerve.
Variations. It may receive a slip from the deep fascia of the forearm.
είσαι
THE MUSCLES AND FASCIE OF THE THIGH
Superficial fascia.-The greater part of this is of loose adipose tissue, and, without
any deep connections, is continuous with the superficial fascia of the abdomen
and back. In the upper and front part of the thigh a deep layer of a more
membranous structure may be distinguished, and this has deep connections where
the lower limb joins the trunk, being attached to Poupart's ligament, the crest of
the ilium, and the deep fascia just below its insertion into the rami of the pubes
and ischium. Below the inner half of Poupart's ligament several lymphatic glands
are arranged longitudinally between these two layers of the superficial fascia.
The deep fascia or fascia lata is a very strong layer of fibrous tissue, the fibres of
which are arranged for the most part transversely as an aponeurosis of investment;
but many of them, especially upon the outer side where it is much thicker, are
longitudinal, and serve for the insertion of important muscles. The whole of the
deep fascia forms a strong cylindrical tube investing all the muscles of the thigh.
It is attached above, in the groin, to Poupart's ligament, where it blends with the
aponeurosis of the external oblique; on the outer side and behind, to the outer
lip of the crest of the ilium, and to the lower part of the vertebral aponeurosis;
upon the inner side, to the border of the tuberosity and ascending ramus of the
ischium, to the descending ramus of the pubes, the symphysis pubis, and
the anterior lip of the crest of the pubes. Below, it becomes much thinner,
and is continuous with the deep fascia of the leg; it has also a deep attach-
ment to the tuberosities of the tibia and the outer surface of the head of the
fibula. The thickening of its outer portion, which passes down like a tendon to the
external tuberosity of the tibia, and is also attached to the outer side of the
ligamentum patellæ, is called the ilio-tibial band. From the deep surface
of this great cylindrical tube are given off various processes which assist in the
formation of the sheaths of some of the more superficial muscles. There are
FASCIE OF THE THIGH
365
also three strong intermuscular septa, which extend from it to the linea aspera
dividing the flexor, extensor, and adductor groups of muscles from one another
At the upper part of the thigh, below the inner third of Poupart's ligament, is the
saphenous opening, for the passage of the internal saphenous vein, which, after
running up the thigh in the superficial fascia, enters the deep femoral vein in this
situation. This opening is not, as might have been expected from the character
of these openings in other parts, a mere circular foramen. It is formed by the
division of the fascia lata into two parts, which do not unite together again, but
are inserted separately along the line of attachment of the lower limb to the trunk.
It begins below the inner third of Poupart's ligament, and is of a somewhat
oval shape, measuring about one inch from above downwards, and half to
three-quarters of an inch from side to side. The lower border of the opening
FIG. 285.-OBLIQUUS EXTERNUS AND FASCIA LATA.


Obliquus
internus
Aponeurosis
of obliquus
externus
Spermatic
cord
Origin of
cremaster
Triangular
fascia
Insertion of.
cremaster
Loops of
cremaster
Obliquus
externus
-Intercolumnar
fibres
-Poupart's
ligament
-External
abdominal
ring
Saphenous
opening
forms a well-defined edge which occupies the angle between the saphenous and
femoral veins close to their point of junction. Externally, the fascia lata is
attached above along the whole length of Poupart's ligament, and its free internal
edge arches inwards towards the spine of the pubes in front of the femoral vein.
This external and broad division of the upper part of the fascia lata is called its
iliac portion, and the free edge which lies in front of the femoral vessels is known
by the name of the falciform ligament. Internally, the fascia lata is in close
contact with the pectineus muscle which lies beneath it, and with that muscle it
dips beneath the femoral vein and the sheath of the vessels to be attached to
the ilio-pectineal line. This internal division is called the pubic portion of the
fascia lata. The deep layer of the superficial fascia stretches across the opening,
and is firmly attached to the edge of the falciform ligament. From the numerous
openings which give passage to the vessels and lymphatics, it is here called the
cribriform fascia (cribrum being the Latin for a sieve).
366
THE MUSCLES
MUSCLES OF THE FRONT OF THE THIGH
In front of the thigh there is a group of four muscles, the chief function of
which is to flex the hip joint. Two of these muscles arise within the abdomen,
and two from the margin of the innominate bone. The two which come from
within the abdomen are the psoas and iliacus, and they act together as one muscle,
and have been described as such under the name of the ilio-psoas. The third
and fourth are the sartorius and pectineus.
1. PSOAS
The psoas, or psoas magnus-named from the Greek word vóa, meaning the
muscles of the loins-is thick, rounded, and fusiform.
Origin.-Inner part, by five processes which arise from (1) the sides of the
intervertebral cartilages which intervene between the bodies of the last thoracic
and the five lumbar vertebræ; and (2) the adjacent part of the sides of the bodies
of these vertebræ; and between these processes from (3) tendinous arches which
bridge over the sides of the bodies of these vertebræ. Outer part, from the lower
border and the front of the transverse processes of all the lumbar vertebræ.
Insertion. The lower and back part of the lesser trochanter of the femur.
Structure. With the exception of the small tendinous arches which span
the side of each of the four upper lumbar vertebræ from its upper to its lower
border, and which give passage to the lumbar vessels, the whole origin of the muscle
is fleshy. The fibres pass downwards and forwards in penniform fashion, but with
a slight convergence, to the inner side of the tendon, which, beginning in the
interior of the muscle about the level of the crest of the ilium, becomes free upon
its outer and posterior surface a short distance above Poupart's ligament, while
upon its inner surface it receives fibres down to its insertion. The muscle,
having hitherto run in a downward, forward, and slightly outward direction,
changes its course at Poupart's ligament, and passes downwards and backwards
to be attached to the lesser trochanter of the femur. In its passage along the
brim of the pelvis and over the lower part of the iliac fossa, the tendon upon
its anterior and outer aspect begins to receive the insertion of the iliacus
muscle. Between the tendon and the capsule of the hip joint which is in close
connection with it, is placed a bursa which frequently communicates through
an opening in the capsule with the interior of the hip joint.
Nerve-supply. From the anterior primary branches of the second and third
lumbar nerves by filaments which are given off from the lumbar plexus whilst it is
passing through the muscle.
Action.--The psoas is a powerful flexor of the thigh upon the pelvis, e.g. in
walking, running, or going upstairs. The change in the direction of the tendon
after crossing the horizontal ramus of the pubes makes its insertion nearly per-
pendicular to the axis of the femur. The psoas therefore acts with less mechanical
disadvantage than is usual with the muscles of the limbs. It has been sometimes
described as an external rotator of the hip; and its insertion into the lesser
trochanter at the inner side of the femur would appear to favour this view; but a
little consideration will show that, although it is attached on the inner side of the
femur, yet on account of the angle which the neck of the femur forms with its shaft
this point of attachment is really external to the axis about which the rotation
of the femur takes place. It will follow, therefore, that any power of rotation
exercised by this muscle will be rather internal than external.
Acting from below, the psoas will flex the lower thoracic and the lumbar spine


PSOAS
367
upon the pelvis and the pelvis upon the thigh, as when the body is raised from the
reclining to the sitting position, or when the trunk is bent forwards in rowing.
Relations. The front and inner surfaces are covered by the iliac fascia, which
at the upper part of the muscle is thickened, and forms the ligamentum arcuatum
internum of the diaphragm. In front lie also the peritoneum, the intestines, the
renal vessels, the spermatic or ovarian vein, and the ureter. On the outer side is
the iliacus muscle. In the interior of the muscle is the lumbar plexus, the nerves
from which run for some distance in its substance. On the inner side lies the
FIG. 286.-PSOAS, ILIACUS, AND QUADRATUS LUMBORUM.

Unde
Quadratus lumborum-
Psoas
magnus
Iliacus
Psoas parvus-
Iliacus
Pyriformis
Obturator externus
Psoas magnus
Intertransversalis
anterior
Quadratus
lumborum
external iliac artery; and behind is the vertebral column, the inner border of the
quadratus lumborum, and the brim of the pelvis. In the thigh, after passing
beneath Poupart's ligament, it is covered by the femoral artery, the pectineus lies
along its inner border, and the capsule of the hip joint lies behind it, together
with the intervening bursa.
Variations. Sometimes the part of the psoas which arises from the lower lumbar
vertebræ forms a distinct muscle. Occasionally fibres from the psoas parvus join the
psoas magnus.
368
THE MUSCLES
2. ILIACUS
The iliacus named from its attachment to the ilium-is a thick, triangular
sheet.
Origin. (1) The upper surface of the ala of the sacrum; (2) the front of the
ilio-lumbar, lumbo-sacral, and anterior sacro-iliac ligaments; (3) the upper and outer
half of the venter of the ilium; (4) the origin of the upper tendon of the rectus
femoris and the ilio-femoral ligament near the anterior inferior spine of the ilium.
Insertion.--(1) The outer surface of the tendon of the psoas, through which
it is attached to the back of the lesser trochanter of the femur; (2) the upper and
inner part of the shaft of the femur in a line about one inch long leading downwards
from the lesser trochanter.
Structure.-Arising by fleshy fibres, the muscle converges in a fan-shape down-
wards and inwards, and its fibres enter the posterior and outer surface of the tendon
of the psoas muscle from about two inches above Poupart's ligament to its insertion.
The lowest fibres are also continued, still fleshy, into their insertion on the inner
part of the shaft of the femur.
Nerve-supply. From the lumbar plexus (through the second and third lumbar
nerves) by the anterior crural nerve, which gives branches to its anterior surface
about the middle of its inner border.
Action. Similar to that of the psoas, as a flexor of the thigh; and acting from
the femur as a fixed point, it will draw forwards and flex the pelvis upon the thigh.
Relations. The iliac fascia in front separates it from the peritoneum and
intestines. The profunda femoris artery and several nerves from the lumbar plexus
lie upon it. Behind, and to its inner side, lies the psoas. After passing under
Poupart's ligament, it is crossed by the sartorius, and behind lie the rectus femoris
and the capsule of the hip joint.
Variations. A small detached muscle occasionally arises from the anterior inferior
spine, and is inserted into the lower part of the anterior intertrochanteric line, or the ilio-
femoral ligament.

PSOAS PARVUS
The psoas parvus-a small muscle, only occasionally present, named from its position
in the loins and its small size-is fusiform and somewhat flattened.
Origin. The side of the intervertebral disc between the last thoracic and the first
lumbar vertebra and the adjacent borders of the bodies of these vertebræ.
Insertion. The ilio-pectineal line.
Structure. Arising fleshy, the fibres converge and are inserted in a somewhat penni-
form manner into the back and inner surface of a tendon which appears about two inches
below the origin of the muscle upon its outer and anterior aspect, and becomes free about
the level of the fifth lumbar vertebra. The tendon, a narrow fibrous band, lies upon the
inner aspect of the psoas magnus on the brini of the pelvis, and expands at its lower
extremity to be attached along the ilio-pectineal line and the pectineal eminence.
Nerve-supply. By small filaments from the first nerve of the lumbar plexus.
Action. To flex the pelvis upon the thorax; or, taking the pelvis as a fixed point, it
will flex the lower part of the thoracic spine as well as the lumbar spine upon the pelvis.
It is a muscle which is well developed in some animals, having for its function the drawing
forwards of the lower part of the pelvis, accompanied by the arching of the lumbar spine
which is seen when they are running swiftly.
Relations. In front, the iliac fascia, peritoneum, ligamentum arcuatum internum,
intestines, renal vessels, ureter, external iliac vessels, etc. Behind and externally, the
psoas magnus.
Investing the abdominal portion of the ilio-psoas is a strong membrane, called
the iliac fascia, which is attached to the crest of the ilium externally, and internally
to the posterior part of the ilio-pectineal line which forms the brim of the pelvis.
SARTORIUS
369
Between these attachments it invests the front of the iliacus and psoas muscles.
Above, it is continued upwards as the covering of the latter muscle, at the sides of
which it is attached to the transverse processes and bodies of the lumbar vertebræ,
as well as to the intervertebral discs and the small tendinous arches which bridge
the side of the bodies of these vertebræ. At the diaphragm it is thickened, and forms
the ligamentum arcuatum internum; near the tips of the transverse processes of
the lumbar vertebræ it is attached to the anterior layer of the lumbar fascia
(page 434). Below, it joins beneath the outer half of Poupart's ligament with the
transversalis fascia, but internal to this it passes downwards into the thigh, forming
with the transversalis fascia the sheath of the femoral vessels. Still further
inwards, it is continuous with the pubic portion of the fascia lata which invests
the pectineus muscle, and it also sends backwards a septum between the psoas
and the pectineus which is attached to the ilio-pectineal eminence.
3. SARTORIUS
The sartorius-named somewhat erroneously from sartor, a tailor, because it
has been supposed to be the muscle by which the cross-legged sitting posture is
produced-is a long, ribbon-shaped muscle slightly fusiform at the two ends.
Origin. The anterior superior spine of the ilium and the adjacent part of the
notch between this process and the anterior inferior spine.
Insertion.-(1) The front part of the inner surface of the tibia, just internal to
the tubercle; (2) the upper part of the deep fascia covering the internal surface of
the leg.
Structure.-Arising by short tendinous fibres, the fleshy fibres which are the
longest in the whole body, run parallel to one another inwards and downwards
across the front of the thigh, and after reaching the inner surface of the thigh about
the middle, the muscular band runs almost vertically downwards to the back of the
internal condyle of the femur. At this point the tendon of insertion makes its
appearance as an aponeurosis which covers the deep aspect of the muscle and
becomes free from fleshy fibres just below the knee joint, where it turns forwards
and covers the inner surface of the inner tuberosity of the tibia, being separated
from it as well as from the tendons of the gracilis and semi-tendinosus by a large
bursa. The upper border of this aponeurosis is thick and tendinous and is inserted
directly into the bone. The lower part of the aponeurosis, which is of a much more
membranous character, is continued downwards and forwards and blends with the
deep fascia of the inner side of the leg, of which it is one of the chief constituents.
Nerve-supply. From the second, third, and fourth branches of the lumbar
plexus, by filaments which are usually derived from the middle cutaneous branch
of the anterior crural nerve as it pierces the muscle at the junction of its middle and
upper thirds.
Action.-(1) To flex the thigh, and at the same time rotate it slightly outwards
and abduct it. (2) To flex the knee, and when the knee is in the bent position it
will also help in rotating the leg inwards. (3) Being contained in the close-fitting
sheath formed by the fascia lata and its deep processes, it will tend when it con-
tracts to draw the soft parts upon the inner surface of the thigh forwards, and so
make tense the inner portion of the fascia lata. (4) Acting from below, it will flex
the pelvis upon the thigh.
Relations. In front above lies the fascia lata; internally below lie the fascia
lata and internal saphenous vein; beneath lie the rectus femoris, iliacus, pectineus,
adductor longus and magnus, vastus internus, and the inner hamstring tendons, the
femoral vessels, the anterior crural nerve and its internal saphenous and vastus
internus branches.


BB

370
THE MUSCLES
Variations. The sartorius is occasionally absent; it may also be divided longitudinally.
It may have insertions into the fascia lata, or the ligamentum patellæ. A tendinous
intersection sometimes crosses the muscle.
FIG. 287.-MUSCLES OF THE FRONT OF THE THIGH.
Psoas
Iliacus
Gluteus medius
Pectineus
Gluteus minimus
Tensor vaginæ femoris
Adductor brevis
Adductor longus
Gracilis
Adductor magnus
Vastus internus
Tendon of sartorius.
Sartorius
Rectus femoris
Ilio-tibial band of fascia lata
Vastus externus
Ligamentum patellæ
4. PECTINEUS
The pectineus-named from pecten (=pubes) on account of its origin from that
bone-is a quadrilateral sheet.
Origin. (1) The ilio-pectineal line between the spine of the pubes and the
PECTINEUS-GLUTEUS MAXIMUS
371
ilio-pubal eminence; (2) the surface in front of the inner end of this line; and
(3) the deep surface of the pubic portion of the fascia lata close to its attachment
to the ilio-pectineal line.
Insertion. The back of the femur in a vertical line about two inches long,
beginning just behind the lesser trochanter.
Structure. The origin is by fleshy and tendinous fibres intermingled. The
fibres then run parallel to one another to a tendinous insertion between the iliacus
and the adductor brevis. The direction of the surfaces changes so that that which
looks forwards above is directed outwards below.
Nerve-supply. From the lumbar plexus (through the third and fourth lumbar
nerves), by a branch of the anterior crural nerve, which, after passing behind the
femoral artery and vein, enters the muscle about the middle of its external border.
When there is an accessory obturator nerve, it passes over the brim of the pelvis
to supply this muscle at the upper part of its anterior surface. Occasionally the
muscle receives a branch upon its deep surface from the anterior division of the
obturator nerve.
Action.-To flex and at the same time adduct the thigh; as, for example, in
crossing the legs, when one thigh is brought forwards and inwards to place it in
front of the other thigh. It is also a slight external rotator. Its predominant
action is that of flexion, as is indicated by the fact that it receives the same nerve-
supply as the sartorius and ilio-psoas. The tendency which it has to adduct during
flexion is counteracted by the slight abduction produced by the sartorius. They
will together produce a slight external rotation, as may be observed during the
advance of the leg in walking..
Relations.--In front, the pubic portion of the fascia lata, the femoral and
profunda vessels, and at its insertion the psoas and iliacus muscles; behind, the
adductor brevis, obturator externus, hip joint, and obturator nerve.
Variations. Sometimes a slight blending of the lower fibres of the pectineus with the
adductor longus has been observed.
THE GLUTEAL MUSCLES
These are arranged in three layers.
FIRST LAYER
The first layer consists of two muscles-the gluteus maximus and the tensor
vaginæ femoris.
1. GLUTEUS MAXIMUS

The gluteus maximus (figs. 291, 303)-named from its great size and from the
region which it occupies (yλOUTÓS = the buttock) is a very thick and strong
rhomboidal sheet.
-
Origin. (1) The posterior fifth of the outer lip of the crest of the ilium, and the
outer surface of the ilium between the outer lip of the crest and the superior gluteal
line; (2) the lumbar aponeurosis between the posterior superior spine of the ilium
and the side of the sacrum; (3) the lateral portion of the posterior surface of the
two last pieces of the sacrum; (4) the side of the coccyx; (5) the back of the
great sacro-sciatic ligament; (6) in front of its attachment to the ilium a few of
its fibres arise from the strong process of the fascia lata which invests the gluteus
medius.
BB 2
372
THE MUSCLES
Insertion.-(1) The upper part of the strong aponeurosis of the fascia lata,
called the ilio-tibial band; (2) the gluteal ridge of the femur which leads from
the lower border of the greater trochanter to the linea aspera; (3) the adjacent
part of the tendinous origin of the vastus externus.
Structure. Its origin is almost entirely fleshy, a few tendinous fibres only
being intermingled between the coarse bundles which run parallel to one another
downwards and outwards to the aponeurosis of insertion. The upper half of this
aponeurosis passes over the outer surface of the great trochanter to be attached
to the upper part of the ilio-tibial band. Lower down the insertion consists of
short tendinous fibres, which are not only attached to the rough process of the
bone but to the adjacent tendon of the vastus externus, while the more superficial
fibres still pass on to be attached to the fascia lata. The whole muscle forms a
parallelogram of which the upper and lower parallel sides are formed by the origin
and insertion which run in oblique lines downwards and inwards, while the outer
and inner borders of the muscle running downwards and outwards form the other
two sides of the parallelogram. This muscle is especially remarkable for the large
size of the fasciculi in which its fleshy fibres are arranged, and which give the
muscle its peculiarly coarse appearance.
There are two well-marked bursæ in connection with the deep surface of this
muscle: the one covering the tuberosity of the ischium, which is partly covered by
the muscle and partly projects from the middle of its lower border in such a way
that when the thigh is extended it intervenes between the muscle and the pro-
minence of bone, and when the thigh is flexed it lies between the tuberosity of
the ischium and the subcutaneous fat. The second is a large, often multilocular
cavity which separates the outer surface of the great trochanter from the apo-
neurosis of insertion of the upper part of the muscle. A small bursa is also
occasionally found between the lower part of the muscle and the tendon of the
vastus externus.
Nerve-supply. From the sacral plexus (through the fifth lumbar and the first
and second sacral nerves), by means of the inferior gluteal branches of the small
sciatic nerve which enter the deep surface of the muscle close to its inferior and
internal border.
Action. To extend the hip joint. The upper part of the muscle, passing over
the great trochanter, is placed at a considerable distance from the axis of movement
which passes through the centre of the hip joint. A similar object is obtained by
the insertion of the lower fibres of the muscle at some distance down the back
of the femur. The whole muscle therefore is able to act as an extensor of the
hip joint with much less mechanical disadvantage than is usual in the body.
The gluteus maximus is not used in the movements of extension which require
but little muscular power, such as those which draw the thigh backwards in
walking; for this purpose the contraction of the hamstring muscles at the back of
the thigh is alone employed. Where, however, a greater effort is required, as in
ascending a hill or in running and leaping, the gluteus maximus acts with great
power.
It has some influence as an external rotator. With respect to abduction and
adduction, the action of the muscle is neutral.. Acting alone, its upper fibres will
assist in the former, and its lower fibres in the latter movement. By means of the
ilio-tibial band it makes tense the outer portion of the fascia lata and is able to
exert some force in the extension of the knee, especially when that movement is
nearly completed. Taking its fixed point from below, the gluteus maximus is a
powerful extensor of the pelvis and in some degree of the lower part of the spine,
e.g. in rising from the stooping position or where the trunk in a sitting posture is
drawn forcibly backwards as in the action of rowing. The influence which it has
upon the back by means of its attachment to the lumbar aponeurosis is shown by
TENSOR VAGINE FEMORIS-GLUTEUS MEDIUS
373
the great pain which is felt in rising from the stooping position when there is any
inflammation of the fasciæ in this region, as in lumbago.
Relations. Behind, the thick adipose tissue of the buttock and the fold which
forms its lower limit, and numerous cutaneous nerves; in front, the gluteus medius,
pyriformis, gemelli and obturator internus, quadratus femoris, adductor magnus,
biceps, semi-tendinosus and semi-membranosus, the gluteal, sciatic and pudic vessels,
the great and small sciatic, the pudic and internal obturator nerves, the two sacro-
sciatic ligaments, the tuber ischii, and great trochanter.
Variations. These are rare. Occasionally a bilaminar arrangement has been observed.
2. TENSOR VAGINE FEMORIS
The tensor vaginæ femoris (figs. 287, 303)-named from its function of making
tight the fascia lata, or sheath of the thigh (=vagina femoris)-is an elongated,
four-sided sheet.
Origin. (1) The front of the outer lip of the crest of the ilium; (2) the
upper part of the notch between the anterior superior and the anterior inferior
spines of the ilium; (3) the inner surface of the fascia lata, by which it is closely
invested.
Insertion.--The fascia lata about one-fourth of the way down the outer side of
the thigh.
Structure. The muscle consists of parallel fleshy fibres which arise by a
short tendinous sheet, pass obliquely downwards, outwards, and backwards, and are
inserted between two layers of the upper part of the strong aponeurosis of the fascia
lata on the outside of the thigh called the ilio-tibial band, which also gives attach-
ment to the majority of the fibres of the gluteus maximus. The two muscles meet
by their adjacent borders a little below the upper part of the greater trochanter at
an angle of about 60°. As they pass upwards, the two divisions of the fascia lata
form a strong sheath for the muscle.
Nerve-supply. Through the fourth and fifth lumbar nerves, and the first sacral,
by the terminal branch of the superior gluteal nerve which enters the muscle
about the middle of its deep surface near its posterior border.
Action. To abduct and rotate inwards the thigh, and, taking its fixed point
from below, to support the pelvis and to rotate the other side of it forwards. Acting
with the gluteus maximus, it will draw upwards the ilio-tibial band, the obliquity of
its fibres enabling it to counteract the tendency of that muscle to draw the band
backwards. The chief consequence of this traction upon the ilio-tibial band will
be to assist in the latter part of the extension of the leg, by the drawing upwards
of the external tuberosity of the tibia.
Relations. Superficially, the fascia lata and the origin of the sartorius;
deeply, the deeper layer of the fascia lata, the gluteus medius, the upper part of
the rectus femoris and the vastus externus, with some of the branches of the
external circumflex artery.
SECOND LAYER

The second layer consists of one muscle-
GLUTEUS MEDIUS
SASD
The gluteus medius (fig. 288)-named from its size and position, which are
intermediate between those of the great and small gluteal muscles-is a strong
triangular sheet.

374
TO THE MUSCLES

Origin. (1) The anterior four-fifths of the outer lip of the crest of the ilium;
(2) the outer surface of the ilium, bordered above by the middle portion of the outer
lip of the crest of the ilium, and in the posterior fifth by the superior gluteal line,
below by the middle gluteal line; (3) the strong process of the fascia lata which
invests the outer surface of the muscle and separates it behind from the gluteus
maximus; (4) the intermuscular septum which intervenes between it and the
gluteus minimus just below the anterior superior spine of the ilium.
Insertion. The well-marked oblique impression extending from the posterior
superior to the anterior inferior angle on the outer surface of the greater trochanter.
Structure.-Arising by fleshy and tendinous fibres intermingled, the muscle
converges fanwise upon both surfaces of a strong flat tendon which is visible
rather higher upon the deep than the outer surface of the muscle. The front part of
the muscle is stronger, and it gradually decreases in thickness towards its posterior
edge. A bursa is contained between the deep portion of the tendon and the
triangular space that lies in front of the impression upon the outer surface of the
greater trochanter.
Nerve-supply. From the fourth and fifth lumbar nerves, and the first sacral
nerve by branches of the superior gluteal nerve which enter the deep surface of the
muscle near the middle of its posterior border.
Action.--To abduct the hip joint. It will also by its thicker and stronger
anterior fibres rotate the thigh inwards. Its posterior fibres, on the other hand,
which are not so strong will tend slightly to rotate the thigh outwards. Acting
from below, it tends to support the pelvis upon the femur and to approximate the
crest of the ilium to the great trochanter. This is by far the most important and
frequent of its actions. In walking, if it were not for the powerful contraction of
the gluteus medius and its associated muscles the gluteus minimus and the tensor
vaginæ femoris, the pelvis would not be held firm upon the upper part of the thigh
when one leg is upon the ground and the other is being advanced in the forward
step. In fast walking the rotatory action of the muscle comes into play, for not
only does the gluteus medius of the limb which is resting upon the ground support
the pelvis by drawing downwards the crest of the ilium, but, by drawing backwards
the front portion of that crest, it throws forwards the opposite side of the pelvis and
increases the length of the stride.
Relations. Superficially, the fascia lata, gluteus maximus, and tensor vaginæ
femoris; deeply, the gluteus minimus, superior gluteal vessels and nerve, and the
great trochanter.

Variations. Sometimes a partially distinct bundle of fibres is inserted into the front of
the upper border of the greater trochanter. A slip may be given from the lower border to
the pyriformis.
THIRD LAYER
The third layer consists of one muscle-the gluteus minimus-which is con-
tinuous with the external rotators which form the next group.
GLUTEUS MINIMUS
The gluteus minimus (fig. 290)-named from its position and smaller size-
is a thick triangular sheet.
Origin. (1) The outer surface of the ilium between the middle and inferior
gluteal lines; (2) a fibrous septum which intervenes between its fibres and those of
the gluteus medius below the anterior superior spine; (3) the front of the capsule
of the hip joint.
GLUTEUS MINIMUS-PYRIFORMIS
375
Insertion. The well-marked vertical impression which forms the anterior
border of the greater trochanter.
Structure. From the fleshy origin the fibres converge fanwise upon the deep
surface of the tendon which makes its appearance about half-way down the muscle
upon the front part of its outer surface and covers the whole of the outer surface of
the muscle from this point down to its insertion. By its anterior border this
muscle is closely blended with the anterior border of the gluteus medius and with
some of the ligaments of the hip joint. Like the preceding muscle, it is also much
thicker and stronger in front.
Nerve supply. From the same sources as the preceding by the superior
gluteal nerve, which distributes filaments to the middle of its outer surface near
its posterior border.
Action.-The same as the preceding: viz. to abduct and rotate inwards the
hip joint; and when it takes its fixed point from below, as is most usually the
case, to flex the pelvis laterally and at the same time to rotate the other side
forwards.
Relations. Superficially, the gluteus medius, the superior gluteal vessels and
nerve; deeply, the capsule of the hip joint, and posterior head of the rectus
femoris.
Variations. The front part of the muscle may be separate from the rest. It occa-
sionally sends slips to the adjacent muscles.
THE EXTERNAL ROTATORS OF THE THIGH
This group consists of six somewhat short muscles, which run transversely
from the pelvic bones to the femur, and which follow immediately after the lower
fibres of the gluteus minimus-viz. the pyriformis, the obturator internus with
the two gemelli, the quadratus femoris, and the obturator externus.
1. PYRIFORMIS
The pyriformis-named from its pear shape (pirus-pear)-is a thick triangular
sheet.
Origin. (1) The side of the front of the sacrum between the first, second,
third, and fourth foramina; (2) the deep surface of the great sacro-sciatic ligament;
(3) the posterior border of the innominate bone at the upper part of the great sacro-
sciatic notch.
Insertion. A small facet upon the inner aspect of the anterior part of the
upper border of the greater trochanter.
Structure. The greater part of the muscle arises by three fleshy slips on the
ridges of bone between, and external to, the anterior sacral foramina. From this
origin, which receives accessory slips of small size from the great sacro-sciatic
ligament and the upper portion of the great sacro-sciatic notch, the fibres converge
as they pass transversely outwards and somewhat backwards through the great
sacro-sciatic foramen. The tendon is first visible upon the deep aspect of the
muscle, and it becomes free near the posterior border of the greater trochanter.
Shortly before its insertion it is closely blended with the tendon of the obturator
internus muscle.
Nerve-supply. From the sacral plexus by small branches which pass from
the second sacral nerve into the anterior surface of the muscle near its origin.
Action.--To rotate the thigh outwards. When the thigh is fixed, it will rotate

376
THE MUSCLES
the pelvis so that the face is turned to the opposite side; if the thigh be flexed, the
pyriformis will abduct it.
Relations. In front, the sacral plexus and rectum, the back of the hip
FIG. 288.-THE EXTERNAL ROTATORS AND THE HAMSTRING MUSCLES.

Gluteus medius
Pyriformis
Gemellus superior
Gemellus inferior
Quadratus femoris
Gluteus maximus
Vastus externus
Biceps
Crureus
Short head of biceps
Plantaris
Gastrocnemius
20
-Obturator internus
-Adductor magnus
Gracilis
Semi-tendinosus
Semi-membranosus
Sartorius
Semi-tendinosus
joint, and some of the branches of the internal iliac artery; behind, the gluteus
maximus; above, the gluteus medius and minimus, the superior gluteal vessels
and nerve; below, the coccygeus, the lesser sacro-sciatic ligament and gemellus
OBTURATOR INTERNUS AND GEMELLI
377
superior, the sciatic and pudic vessels, and most of the branches from the sacral
plexus.
Variations. The pyriformis may be absent. It is often divided by a part of the great
sciatic nerve into two muscles, and sometimes into three. It may be more or less blended
with the gluteus medius or minimus above, and the superior gemellus below.
2, 3, AND 4. OBTURATOR INTERNUS AND GEMELLI
The obturator internus and gemelli form really a single muscle, the greater
part of which arises inside the pelvis; while the gemelli form two accessory slips
which join it from the margin of that cavity.
The obturator internus-named from the fact that it arises from the membrane
which closes up the obturator foramen, and from its position within the pelvis-is a
somewhat triangular sheet, or rather, perhaps, it should be described as the sector
of a circle, for its origin within the pelvis is bounded by a curved line like a part of
the circumference of a circle.
Origin. The whole of the interior of that part of the pelvis which is formed by
the innominate bone: viz. (1) The back of the body and descending ramus of the
os pubis, and of the ascending ramus of the ischium; (2) the whole of the inner
surface of the obturator membrane; (3) the broad surface of bone behind the
foramen, corresponding to the acetabulum on the exterior; (4) the outer surface
of the pelvic and obturator fasciæ. These extend from the ilio-pectineal line above
to the great sacro-sciatic foramen behind, and to the spine and tuberosity of the
ischium below.
Insertion. The inner aspect of the upper border of the greater trochanter at
the point where it unites with the upper border of the neck of the femur.
Structure. The muscle arises fleshy from the whole of the interior of the
pouch-like cavity formed by the pelvic and obturator fascia internally and the
wall of the pelvis externally, which opens backwards and downwards at the lesser
sacro-sciatic foramen. From this extensive origin the fibres converge down-
wards and backwards upon a broad tendinous expansion which begins about one
inch above the lesser sacro-sciatic foramen upon the outer surface of the muscle.
This expansion is corrugated into four or five folds, which are separated from the
cartilaginous lining of the lesser sacro-sciatic notch by a bursal cavity which
allows of the smooth play of the tendon upon the bone. This cartilage presents
corresponding grooves for the folds of the tendon. After passing through this
foramen the tendon changes its course, and is directed transversely outwards and
forwards to its insertion. The fleshy fibres extend upon the inner, which has
now become its posterior surface for about half the distance from the notch to the
facet upon the greater trochanter. For a short distance before its insertion it
is intimately connected with the tendon of the pyriformis.
Nerve-supply. From the first and second sacral nerves of the sacral plexus by
a special nerve which, after passing through the lesser sacro-sciatic notch, is distri-
buted to the muscle, entering its inner surface near its upper border and close to
the lesser sacro-sciatic foramen.
The gemellus superior-named from gemellus a twin, because it is the upper
of the two twin muscles which nearly surround the tendon of the obturator internus
at its point of emergence from the pelvis-is a somewhat triangular sheet curved
upon itself to embrace the rounded tendon of the obturator internus.
Origin. (1) The outer surface of the spine of the ischium; (2) the upper half
of the outer edge of the lesser sacro-sciatic notch.
Insertion. The upper border and the anterior surface of the obturator internus
tendon, about one inch from its insertion..

378
THE MUSCLES
Structure.-Arising fleshy from the bone at the margin of the lesser sacro-
sciatic foramen, the muscular fibres converge slightly and form a sheet which is
curved upon itself so as to fit round the upper border and anterior aspect of the
obturator internus tendon, with which, after a course of about two inches in length,
it blends.
Nerve-supply. The first and second nerves of the sacral plexus by a small
special branch which enters the muscle at the upper part of its anterior surface
near its origin.
The gemellus inferior-the lower of these twin muscles-is also triangular in
shape, but is somewhat broader and stouter than its fellow.
Origin. (1) The upper part of the inner border of the tuber ischii; and (2)
the lower half of the outer edge of the lesser sacro-sciatic notch.
Insertion. The lower border and anterior surface of the tendon of the obturator
internus, about one inch from its attachment to the greater trochanter.
Structure. Its fibres, arising fleshy from the lower half of the outer border of
the lesser sacro-sciatic notch, converge and form a sheet which wraps round the
lower part of the anterior surface of the tendon of the obturator internus. The
two gemelli therefore together form an envelope which embraces the whole of the
tendon of the obturator internus after its emergence from the pelvis, with the
exception of a part of its posterior surface.
Nerve-supply.--From the sacral plexus (through the fifth lumbar and first sacral
nerves), by filaments from the special nerve to this muscle and the quadratus
femoris, which enter the upper part of its anterior surface near its origin.
Action. The obturator internus with its two satellites, the gemelli, powerfully
rotates the femur outwards. It should be observed that, although the fibres are
mostly directed backwards and downwards within the pelvis, the action of the
muscle is really determined by the outward and slightly forward direction of the
tendon outside the pelvis; and the notch upon the bone plays the part of a pulley
in changing the direction of the force.
Besides its action as an external rotator, the muscle will be able to assist abduction
when the thigh is bent through a right angle.
Relations. The obturator internus in the pelvis is in contact externally with
the innominate bone and obturator membrane; above, with the obturator artery and
nerve; internally, with the pelvic and obturator fasciæ, the levator ani, the pelvic
viscera, and the pudic vessels and nerve.
Outside the pelvis, the tendon of the obturator internus, with the gemelli, is in
contact, in front with the capsule of the hip joint and the tendon of the obturator
externus; behind, with the gluteus maximus, great sacro-sciatic ligament, the sciatic
vessels and nerves; above, with the pyriformis and the structures which come out
of the pelvis below it; below, with the quadratus femoris and a branch of the internal
circumflex artery.
Variations. One or other of the gemelli may be absent, but more frequently the upper
one. An accessory slip to the obturator internus has been observed coming from the third
piece of the sacrum.
5. QUADRATUS FEMORIS
The quadratus femoris-named from its square shape and its insertion into
the femur-is a four-sided sheet.
Origin. The upper part of the outer border of the tuber ischii.
Insertion. The vertical ridge which begins just above the middle of the posterior
intertrochanteric line of the femur, and is called the linea quadrati.'
Structure. Its fibres are fleshy and run parallel to one another almost hori-
zontally outwards and slightly forwards..
QUADRATUS FEMORIS-ADDUCTOR LONGUS
379
-
Nerve-supply. From the sacral plexus (through the fifth lumbar and first
sacral nerve) by a special branch which, after furnishing filaments to the inferior
gemellus, enters the muscle near the upper part of its anterior surface close to its
origin.
Action. It approximates the posterior border of the great trochanter to the
tuber ischii, and so assists powerfully in the external rotation of the femur.
Relations.-Behind, the gluteus maximus and the two sciatic nerves; in front,
the obturator externus and the termination of the internal circumflex artery.
Above is the inferior gemellus, and below the adductor magnus.
Variations. This muscle is not unfrequently absent.
6. OBTURATOR EXTERNUS
The obturator externus is a strong external rotator of the thigh, but it is
also an adductor, and on account of its nerve-supply and position it is better
described in that group of muscles.
THE ADDUCTORS
The adductor muscles form a distinct group on the inner side of the thigh,
and are all supplied by the obturator nerve with the exception of a small part of
the adductor magnus. They consist of the adductor longus, adductor brevis, adductor
magnus, gracilis, and obturator externus.

1. ADDUCTOR LONGUS
The adductor longus-so named from its action and its length compared with
that of its immediate neighbour-is a thick triangular sheet.
Origin. A rounded impression on the front of the body of the os pubis
immediately below the crest and angle.
-
Insertion. (1) The lower two-thirds of the inner lip of the linea aspera (in
the middle third of the thigh); and (2) the adjacent internal intermuscular septum.
Structure.-Arising by a strong rounded tendon, which extends about two
inches downwards upon the inner border of the muscle, the fleshy fibres diverge
in a fan-shaped expansion, and are inserted by short tendinous fibres which blend
behind with those of the adductor brevis and adductor magnus.
Nerve-supply. From the third and fourth nerves of the lumbar plexus, by
branches from the anterior division of the obturator nerve which enter the muscle
on the upper part of its posterior surface rather below its middle.
Action. To adduct and flex the femur, and at the same time to rotate it out-
wards.
Relations. In front, the fascia lata, sartorius, vastus internus and femoral
vessels; behind, the adductor brevis and magnus, the profunda vessels, and
obturator nerve; its upper border touches the pectineus.
Variations. The adductor longus may arise by two heads, the outer being attached to the
crest of the pubes, and separate from the ordinary head which arises below the angle. Occa-
sionally the muscle is divided by the passage of vessels into an upper and a lower portion.

380
THE MUSCLES
2. ADDUCTOR BREVIS
The adductor brevis-named from its action and its size as compared with the
preceding muscle-is a thick quadrilateral sheet.
FIG. 289. THE DEEP MUSCLES OF THE FRONT OF THE THIGH.

Obturator externus
Rectus tendon
Gluteus medius
Adductor longus
Gluteus minimus
stophba ad
Adductor magnus.
Adductor brevis
Adductor longus
Vastus internus
Vastus internus
Rectus femoris
Ligamentum patellæ.
Vastus externus
Biceps
ziggra
-Ilio-tibial band
Origin. The body and the descending ramus of the os pubis, below, and some-
what external to, the origin of the adductor longus.
ADDUCTOR BREVIS
381
Insertion. The inner lip of the linea aspera in its upper half, extending from
just below the lesser trochanter to about the middle of the back of the femur.
Structure.-Arising by short tendinous fibres, the muscle diverges into a fan-
FIG. 290.-THE DEEP MUSCLES OF THE BACK OF THE THIGH.

Gluteus minimus
Obturator internus
Obturator externus
Gluteus maximus
Vastus externus
Short head of biceps
Adductor magnus
Crureus
Vastus internus
Tendon of biceps.
shaped fleshy expansion, which ends in short tendinous fibres blending with those
of the adductor longus and adductor magnus.
Nerve-supply. From the third and fourth nerves of the lumbar plexus by the
superficial branch of the obturator nerve, which sends filaments to the anterior
surface of the muscle near the lower part of its upper border. Sometimes, how-
ever, it derives its nerve-supply from the deeper division of the obturator nerve,
and in that case the nerves enter the muscle from behind.
382
THE MUSCLES
Action.-Like the preceding, it is an adductor and rotator outwards of the femur,
but it will not assist so powerfully in flexion.
Relations. In front, the pectineus, adductor longus, the profunda vessels,
and superficial branch of the obturator nerve; behind, the obturator externus
and adductor magnus, and the deep branch of the obturator nerve.
Variations.It is sometimes divided into an upper and a lower portion. Occasionally
it joins above with the obturator externus.
3. ADDUCTOR MAGNUS
The adductor magnus-named from its action and its great size is a thick
fan-shaped sheet, forming a right-angled triangle, the right angle of which is
contained between the side corresponding to the insertion of the muscle at the
back of the femur and the side formed by the free upper border of the muscle.
Origin. (1) The lower part of the outer border of the tuber ischii; (2) the
outer surface of the ascending ramus of the ischium near its inner border; (3)
the front of the outer surface of the descending ramus of the pubes.
Insertion. (1) The back of the femur, in a line beginning at the lower
extremity of the linea quadrati, and extending along the inner border of the gluteal
ridge and the middle of the linea aspera down to its bifurcation; (2) the adductor
tubercle on the upper and posterior part of the internal condyle; (3) the lower
part of the internal intermuscular septum.
Structure. Its origin and insertion are by short tendinous fibres, with the
exception of the insertion of the bundle of fibres which passes from the tuber ischii
to the adductor tubercle. These arise by a long tendon above, and again become
tendinous three or four inches above the knee joint, so as to form a long and con-
spicuous tendon on the lower part of the inner border of the muscle. Between
this part of the insertion of the muscle and the linea aspera, the fibres are attached
to the back of the internal intermuscular septum and to a tendinous arch which
allows of the passage of the femoral artery and vein from Hunter's canal into the
upper part of the popliteal space. Between the origin and insertion the fibres
diverge; the anterior fibres of origin passing horizontally outwards to their inser-
tion into the upper part of the back of the femur, while the fibres which arise
behind pass vertically downwards between the tuber ischii and the internal
condyle. Moreover, the muscle is twisted upon itself so that the surface which
above looks inwards and rather backwards is directed forwards below. A deep
longitudinal groove is thus formed upon the upper part of the back of the muscle,
in which lie the hamstring muscles and the great sciatic nerve. The upper part
of the muscle, which arises in front, and is inserted into the inner border of the
gluteal ridge, forms a triangular sheet, usually separate from the rest, and some-
times described as a distinct muscle, the adductor minimus.
In addition to the opening for the femoral vessels, the muscle is pierced close to
the bone by the perforating arteries and the terminal branch of the profunda
femoris. Upon its anterior surface it receives a membranous expansion from the
vastus internus, which passes inwards beneath the sartorius to the adductor
longus and magnus, forming the anterior wall of a sort of tunnel which con-
tains the femoral vessels in the middle third of the thigh, and is called Hunter's
canal.
Nerve-supply.-Chiefly from the third and fourth nerves of the lumbar plexus
by the deep division of the obturator nerve which supplies the muscle upon the
outer part of its anterior surface. The lower fibres of the muscle, however, are
supplied upon their posterior surface by the great sciatic nerve, a branch of the
sacral plexus.
ADDUCTOR MAGNUS-OBTURATOR EXTERNUS
383
Action.-This muscle is the most powerful of the adductors. The upper three
fourths of its fibres will also rotate outwards the femur, while that part of the
muscle which arises from the tuber ischii and is inserted into the inner condyle
will tend slightly to rotate the thigh inwards, and will at the same time extend as
well as adduct the thigh.
Duchenne suggests that this is the part of the muscle which equestrians should
especially develop. Otherwise the adduction of the thighs in gripping the saddle
is apt to throw out the toes, which is ungainly, and, if the rider have spurs on,
may lead to unpleasant consequences.
Relations. In front lie the adductor brevis and longus, and lower down the
vastus internus. Behind are the hamstring muscles, the gluteus maximus, and the
great sciatic nerve. At its upper border are the quadratus femoris and obturator
externus. Along its inner border lie the gracilis and part of the sartorius.
Variations. The posterior part of the muscle may form a distinct slip. Accessory
bundles from the semi-membranosus or biceps may join the lower tendon. The upper
border of the muscle may be blended with the quadratus femoris.
4. GRACILIS
=
The gracilis-named from its form (gracilis slender)-is long and ribbon-
shaped.
Origin. The inner edge of the anterior surface of the body and descending
ramus of the os pubis from about the middle of the symphysis to the junction of
the rami of the pubes and ischium.
Insertion. The inner surface of the tibia below its inner tuberosity, between
the insertions of the sartorius and the semi-tendinosus.
Structure. Arising by a broad and thin aponeurosis, the muscular fibres pass
down the inner surface of the thigh almost parallel to one another, but with a
slight convergence, so that the muscle in descending increases in thickness as it
diminishes in breadth. About two inches above the inner condyle it becomes a
rounded flattened tendon. This runs behind the inner condyle, and, after forming
one of the two hamstring tendons which can be easily felt at the inner border of
the popliteal space, it passes forwards to be inserted in a slightly expanded form
below the inner tuberosity. A few fibres pass from its lower border to the deep
fascia of the leg.
Nerve-supply. From the third and fourth nerves of the lumbar plexus by a
branch from the superficial division of the obturator nerve which enters the deep
surface of the muscle above its middle.
Action. To adduct the thigh and flex the knee.
will help in rotating the leg inwards.

-
When the knee is flexed, it
Relations. It lies superficially in its whole course under cover of the fascia
lata. Upon its deep surface lie the adductor brevis and magnus, and lower down
the semi-membranosus muscle. It has in front of it the sartorius muscle which
overlaps it slightly at the lower part of the thigh, and behind it is the tendon of
the semi-tendinosus. The internal lateral ligament of the knee and a large bursa lie
beneath its tendon.
5. OBTURATOR EXTERNUS
The obturator externus (figs. 286, 289, 290)-named from its attachment to
the obturator membrane upon its outer surface-is a triangular sheet.
Origin. (1) The inner half of the anterior surface of the obturator membrane;
384
THE MUSCLES
(2) the descending ramus of the os pubis immediately internal to the foramen;
(3) the ascending ramus of the ischium internal to the foramen.
Insertion. The digital fossa upon the inner surface of the great trochanter.
Structure. It is a fan-shaped triangular muscle which arises fleshy from the
adjacent surfaces of bone and membrane, in a curve which is convex forwards and
inwards. From this wide origin the fibres converge outwards, and end below the
acetabulum in a rounded tendon which passes behind and in close contact with the
capsule of the joint to its insertion in the digital fossa. Not unfrequently a small
portion of the muscle is separated at its upper border from the rest by one or both
of the divisions of the obturator nerve.
Nerve-supply.--From the third and fourth nerves of the lumbar plexus by the
deep division of the obturator nerve which distributes filaments to the deep surface
of the muscle as it is passing through it.
Action. To adduct and rotate outwards the thigh.
Relations.-Behind, the obturator vessels, and at its insertion the quadratus
femoris; in front, the psoas muscle, the pectineus, and adductor brevis; above, the
obturator nerve, one or both branches of which perforate it, and more externally
the capsule of the hip joint.
THE HAMSTRING MUSCLES
The hamstring muscles form a group at the back of the thigh, separated
by intermuscular septa from the vastus externus on the outer, and the adductor
magnus on the inner side. They consist of the biceps, semi-tendinosus and semi-
membranosus, and are supplied by the great sciatic nerve. Like the gluteus
maximus their action is to extend the hip.
1. BICEPS FEMORIS
The flexor biceps femoris (figs. 288, 290)-named from its two heads-con-
sists of two parts: the longer head being somewhat fusiform, and the shorter a
triangular sheet.
Origin. The long head from (1) the internal and posterior facet at the back of
the tuber ischii by a tendon common to it and the semi-tendinosus; (2) the lower
part of the great sacro-sciatic ligament. The short head from (1) the outer lip
of the linea aspera from a point just above the middle of the bone down to the
bifurcation; (2) the upper two-thirds of the outer division of the linea aspera;
(3) the external intermuscular septum.
Insertion. (1) A fossa below and in front of the styloid process of the head
of the fibula; (2) the deep fascia covering the peronei muscles; (3) the outer
tuberosity of the tibia.
Structure. The origin of the long head is by a short tendon which is con-
tinued down to the middle of the thigh by a septum which divides this muscle
from the semi-tendinosus. From this tendon and the outer surface of the
septum the muscular fibres arise in penniform fashion and form a fusiform belly,
which receives at the junction of the middle and lower thirds of the thigh the
thick sheet of muscular fibres derived from the short outer head. The tendon
commences upon the posterior surface of the muscle near its outer border about
the middle of the thigh. At the back of the external condyle the fleshy fibres
The rounded tendon here widens into a thick aponeurosis, which embraces
the anterior portion of the external lateral ligament at the point of its insertion
into the outer and anterior facet of the head of the fibula. Between this tendon

cease.
BICEPS FEMORIS-SEMI-TENDINOSUS
385
and the external lateral ligament is a bursa. From the borders of the tendon at
this point a thinner aponeurosis is given off to the outer tuberosity of the tibia in
front and the deep fascia of the leg behind.
Nerve-supply. From the first, second and third nerves of the sacral plexus by
the great sciatic nerve which sends branches to the anterior and inner surfaces of
the muscle about the middle of the thigh. The short head of the biceps receives
its supply from the external popliteal nerve.
Action. To extend the hip and flex the knee. Its shorter head flexes the
knee only.
When the knee is flexed, both heads will unite in rotating the leg
outwards. When the knee is extended, the long head will have a slight influence
in rotating the hip outwards. Acting from below, the long head will assist in
raising the body from the stooping position.
Relations. Behind, the plantaris, the outer head of the gastrocnemius, gluteus.
maximus, fascia lata, and the small sciatic nerve. In front, the tendon of the
semi-membranosus, the adductor magnus, and the great sciatic nerve. Upon its
inner border lie the semi-tendinosus, semi-membranosus, and the external popliteal
nerve. Beneath the lower tendon is a bursa which separates it from the external
lateral ligament of the knee joint.
Variations. The short head of the biceps may be absent. Accessory heads may be
derived from the tuber ischii, the upper part of the linea aspera, the fascia lata, or the inner
surface of the tendon of insertion of the gluteus maximus. It may send a slip to the
gastrocnemius.
10 albbins sat
2. SEMI-TENDINOSUS

od of
The semi-tendinosus (fig. 288)-named from the long tendon which forms the
lower half of the muscle-is fusiform and somewhat flattened. loo
Origin. By a tendon which is common to it and the preceding muscle, from
the internal and posterior of the facets at the back of the tuber ischii.
Insertion. (1) The upper part of the inner surface of the tibia below and
behind the insertion of the gracilis; (2) the deep fascia of the inner side of the
leg.
Structure. The rounded and somewhat flattened tendon of about two inches in
length is succeeded by a fusiform mass of muscular fibres, which end just below
the middle of the thigh in a flattened cylindrical tendon. This runs directly down-
wards along the inner side of the popliteal space, where it can easily be felt beneath
the skin, behind and external to the tendon of the gracilis, in company with which
it passes downwards and forwards behind the internal condyle to its insertion
below the inner tuberosity. From the lower border of the flattened tendon an
aponeurosis passes downwards to the deep fascia of the leg. The fleshy part of
the muscle is crossed about its middle by a thin tendinous intersection running
downwards and outwards.
Nerve-supply. From the first, second, and third nerves of the sacral plexus by
means of branches from the great sciatic nerve which enter the outer part of the
deep surface of the muscle two or three inches below the tuber ischii.
Action. To extend the hip and flex the knee, and when the knee is flexed to
rotate the leg inwards. Acting from below, it lifts up the body from the stooping
position.
Relations.-Behind, the gluteus maximus and fascia lata; on its outer side the
biceps; in front, the semi-membranosus, adductor magnus, and near the knee the
gracilis, sartorius, and the inner head of the gastrocnemius. The large bursa
beneath the sartorius tendon also wraps round the upper part of the tendon of
the semitendinosus, and separates it from the internal lateral ligament of the
knee joint.

CC

386
THE MUSCLES
3. SEMI-MEMBRANOSUS
The semi-membranosus (fig. 288)--named from the broad membrane-like
aponeurosis which forms the upper third of the muscle-is strong, flattened, and
fusiform.old ads
Origin. The anterior and outer of the facets upon the back of the tuber
ischii.
Insertion. (1) The lower part of the posterior extremity of the groove upon
the back and inner side of the inner tuberosity of the tibia; (2) by a band of
fibres which pass upwards and outwards to the upper and back part of the external
condyle of the femur, and blend with the posterior ligament of the knee joint; (3)
by a broad expansion which, passing downwards and outwards from its insertion
into the inner tuberosity to the oblique line at the back of the tibia, forms the
aponeurosis which invests the posterior surface of the popliteus; (4) a few fibres
pass downwards and forwards from the lower border of its tibial insertion to blend
with the internal lateral ligament.
Structure. The upper part of the muscle consists of a strong flat tendon
about three-quarters of an inch broad, which extends along the outer border of the
muscle to the middle of the thigh. The tendon of insertion is not quite so broad
but much thicker, and reaches upon the inner border of the muscle also as high as
the middle of the thigh. Between these two tendons the muscular fibres which
are comparatively short pass downwards and inwards, beginning upon the upper
tendon about four inches below the tuber ischii, and ending upon the lower tendon
close to the upper part of the inner condyle. The muscle has therefore a very
distinctly penniform arrangement, but it is peculiar in this respect that the fleshy
fibres are at each extremity attached to a tendon, and are not, as is usually the
case, at one extremity attached to the bone. It is also unusual for a muscle to
have so long a tendon at its proximal end. One effect of this arrangement is to
allow of the free action of the long head of the biceps which crosses over this
part of the semi-membranosus. Otherwise the swelling of the fibres of the biceps
during contraction would have pressed upon and interfered with the action of the
semi-membranosus, which usually contracts at the same time.
Nerve-supply. From the first, second, and third nerves of the sacral plexus by
the great sciatic nerve which sends branches to the deep surface of the muscle
about the middle of the thigh.
Action. To strongly extend the hip and to flex the knee. When the knee is
flexed it will also assist in the internal rotation of the leg, but with less mechanical
advantage than the semi-tendinosus and gracilis, as its line of action is so near to
the axis of movement.
Like most penniform muscles, the semi-membranosus is very powerful, as is
shown by the thickness of its tendons. This strength is necessitated by the fact
that its line of action is so much nearer to the axis of movement both in flexion
and rotation inwards of the knee. Like the other muscles which arise from the
tuber ischii, it will co-operate powerfully in raising the body from the stooping
position, this prominence of bone forming the short arm of the lever by which the
trunk is raised. This group of muscles affords a good example of the peculiar
action obtained by long muscles passing over two joints. If all three muscles
were to remain passive, like so many ligaments, it is obvious that on flexion of the
hip joint by means of the ilio-psoas and other muscles, the hamstrings would
ensure the simultaneous flexion of the knee; or, again, on extension of the knee by
the action of the powerful muscles of the front of the thigh, the hamstrings would
produce a corresponding extension of the hip joint. Seeing, however, that these
hamstrings are not passive, but that they contract powerfully at the same time in
SARTORIUS-QUADRICEPS EXTENSOR FEMORIS
387
many of these movements, it follows that in flexion of the hip in such movements
as those of running, the knee is at the same time flexed with increased rapidity;
and again, when the knees are extended by the powerful contraction of the
quadriceps muscle, the simultaneous action of the hamstring muscles will produce
a still more rapid elevation of the trunk.
Relations of the semi-membranosus.-Behind, the gluteus maximus, biceps, and
semi-tendinosus; in front, the adductor magnus, posterior ligament of knee, and
the popliteus. Along its outer border lies the great sciatic nerve, and just before
its insertion the inner head of the gastrocnemius hooks round this border, being
separated from it by a bursa which communicates with the knee joint. There is
also usually a small bursa between its tendon and the back of the inner tuberosity
of the tibia.
Variations. The semi-membranosus has occasionally been deficient, or only represented
by a thin musculo-tendinous band. It has also been found double.
ANTERIOR MUSCLES OF THE THIGH
This group consists of the sartorius and the quadriceps extensor femoris.
1. SARTORIUS
This muscle has already been described.
2. QUADRICEPS EXTENSOR FEMORIS
The quadriceps extensor femoris (figs. 287, 289), as its name implies, consists
of four heads. Of these, one, the rectus, arises from the innominate bone; and
the three others, the vastus externus, vastus internus, and crureus, from the femur;
while the common tendon is inserted into the upper border and sides of the patella.

(a) RECTUS FEMORIS
The rectus femoris-named from its long straight course is strong, fusiform,
and flattened from before backwards; it arises by an anterior and posterior head.
Origin. Anterior head, from the front of the anterior inferior spine of the
ilium; posterior head, from the upper surface of the rim of the acetabulum just
external to the attachment of the capsular ligament.
Insertion. The front of the upper border of the patella.
Structure. This muscle consists of two strong tendinous expansions joined
by fleshy fibres. The upper expansion is formed above by the union of the two
tendinous heads in a small arch, which is intimately connected with the capsule of
the hip joint. From this arch the tendinous expansion descends upon the front of
the muscle as far as the middle of the thigh, getting thinner and narrower as it
descends. The tendon of insertion begins upon the back of the muscle also about
the middle of the thigh, and soon expands into a broad aponeurosis which covers
the back of the muscle at its lower end; about three inches above the patella, it
becomes free of muscular fibres, and forms a strong tendinous band which is
inserted into the upper border of the patella. The fleshy fibres pass from the back
and sides of the upper expansion to the front and sides of the tendon of insertion.
CC 2

388
THE MUSCLES
Seen from the front, these fleshy fibres appear to diverge on both sides from the
upper expansion, and, after passing round the border of the muscle, they converge
upon the tendon of insertion so as to give the muscle a bipenniform appearance.
Nerve-supply. From the lumbar plexus (through the second, third, and fourth
lumbar nerves), by the anterior crural nerve which sends filaments to the posterior
aspect of the muscle in the upper half of its course.
Action. To assist in the powerful extension of the knee by the quadriceps. It
will also help in flexion of the hip; and it will be a powerful agent in preventing
dislocation of the head of the femur. When the hip-joint is flexed, the muscle will
act chiefly from its posterior head; but when the hip is extended, the anterior head
of the muscle will act with more power.
Relations. In front lie the sartorius, tensor vaginæ femoris, and the fascia lata;
behind, it lies on the hip joint and the crureus muscle; upon its inner border above
is the iliacus; and outside it lie the gluteus medius and minimus.
(b) VASTUS EXTERNUS
The vastus externus-named from its great size and its position upon the outer
surface of the thigh-is a thick rhomboidal sheet.
-
Origin. (1) The upper half of the anterior intertrochanteric line and the front
of the upper part of the femur along the anterior border of the great trochanter;
(2) a horizontal line which forms the lower border of the great trochanter; (3) the
outer lip of the gluteal ridge; (4) the upper half of the outer lip of the linea aspera
and the adjacent portion of the shaft of the femur for about one-sixth of an inch;
(5) the external intermuscular septum in the neighbourhood of its attachment to
the linea aspera.
Insertion. (1) The outer half of the upper border of the patella, behind the
preceding tendon, with which it also blends; (2) the upper third of the outer border
of the patella; (3) by an aponeurosis which is inserted partly into the front of the
external tuberosity of the tibia, partly into the deep fascia of the leg.
Structure. Arising partly directly from the bone, and partly by a strong apo-
neurosis which covers the outer surface of the muscle in its upper two-thirds,
the fleshy fibres run parallel to one another downwards, forwards, and inwards, at
the same time curving slightly as they pass over the rounded mass formed by the
crureus muscle. The aponeurosis of insertion lies upon the inner surface of the
muscle and receives fleshy fibres to within one inch of its insertion into the patella
and its blending with the other tendons of the quadriceps muscle.
Upon its
anterior surface it unites with the tendon of the rectus muscle, and upon its
posterior surface is received a part of the insertion of the crureus.
Nerve-supply. From the anterior crural (through the second, third, and
fourth lumbar nerves), by several branches which enter the internal surface of the
muscle in the upper third of the thigh.
Action and relations. These will be considered with those of the two following
muscles.
(c, d) VASTUS INTERNUS AND CRUREUS
The vastus internus and crureus are so closely blended that it is better to
describe their origins together before mentioning the way in which they may be
separated. They have received their names, the former from its size and position;
the latter from its intimate connexion with the whole of the front of the thigh bone,
the term 'crus' being often used synonymously with the femur. The blended
muscle is a somewhat fusiform sheet which is so curved laterally as to form a
cylinder embracing the whole of the front and sides of the shaft of the femur.
Origin. (1) The outer lip of the lower half of the linea aspera and its external
VASTUS INTERNUS-CRUREUS
389
bifurcation, together with the adjacent external intermuscular septum; (2) the
lower part of the anterior intertrochanteric line and the spiral line of the femur;
(3) the inner lip of the whole length of the linea aspera and its internal bifur-
cation, together with the adjacent part of the internal intermuscular septum, and
the front of the tendon of the adductor magnus; (4) the greater part of the front
and sides of the femur within the limits formed by the three preceding attachments
and the origin of the vastus externus.
Insertion. (1) The posterior aspect of the upper border of the patella; (2) the
upper half of the inner border of the patella; (3) by a strong aponeurosis into
the front of the inner tuberosity of the tibia and into the adjacent deep fascia of
the leg.
Structure. The fibres of this large muscle arise fleshy from the surface of the
femur and converge, from the outer side downwards, forwards, and inwards; from
the front directly downwards; from the inner side downwards, forwards, and out-
wards, upon the back and sides of a strong aponeurosis which covers the front of the
muscle from about the middle of the thigh downwards. The fibres which arise
from the tendon of the adductor magnus and the adjacent intermuscular septum
form the lowest part of the thick muscular belly of the vastus internus, and are
directed almost transversely outwards to get to their insertion upon the inner border
of the patella. The substance of the muscle is arranged in layers which
wrap round
the front and sides of the femur; and between the attachment of these layers to
the bone, longitudinal strips of bone may be found upon dissection without any
muscular attachment. The deepest of these layers in the lower fourth of the
thigh forms a separate sheet of muscular fibre, sometimes called the subcrureus,
which is inserted into the upper reflexion of the synovial membrane of the
knee joint. Beneath this muscle is the bursa underneath the quadriceps, which
in the adult communicates with the upper part of the knee joint.licedid
A somewhat arbitrary division may be made between the vastus internus and
crureus by dissecting at the lower third of the thigh in a line with the inner border
of the patella. With a few touches of the scalpel a longitudinal separation may
be made clear, which extends upwards to the lower part of the anterior inter-
trochanteric line. The part of the muscle external to this line is the crureus, and
the part internal the vastus internus.
The ligamentum patellæ may be looked upon as the common tendon of the
quadriceps. It is a band of fibrous tissue about an inch broad by one-quarter of
an inch thick, and two or three inches in length, which is attached above to the
apex and to the lower part of the posterior surface of the patella; and, after passing
downwards and very slightly outwards, it is inserted into the anterior surface of
the tubercle of the tibia. Attached to its sides are strong aponeuroses by which
the lower fibres of the vastus externus and vastus internus and the ilio-tibial band
are inserted into the tuberosities of the tibia, and which blend on their deep surface
with the lower part of the capsule of the knee joint.
Nerve-supply. Numerous branches from the anterior crural are distributed to
the upper half of the front of the crureus muscle and to the inner surface of the
vastus internus at the junction of the middle and lower thirds of the thigh, the
nerve to the vastus internus being a large and conspicuous branch which lies close
to the outer side of the femoral artery in the upper part of Hunter's canal.
Action.-The vastus externus, crureus and vastus internus, together with the
rectus femoris, extend powerfully the knee. Their intermediate insertion into the
sesamoid bone formed by the patella serves to lift from the line of the tibia the
ligamentum patellæ, which may be looked upon as the lower part of their common
tendon. The enormous power of the whole of this combination of muscles is
necessitated partly by the fact that the whole of the weight of the body has to be
raised by it, and partly by the great mechanical disadvantage which results from


390
THE MUSCLES
the short arm of the lever upon which the tendon acts, and the obliquity of its
insertion.
On account of the direction of the femur, which is downwards and inwards, the
tendency of the quadriceps is to draw the patella outwards at the same time as
upwards. This is in some degree counteracted by the position and direction of the
vastus internus. The great mass of the fibres of this part of the quadriceps arise
in the lower part of the thigh, and are directed so transversely outwards towards
the inner border of the patella, that when they contract they tend to draw the
patella inwards as well as upwards, and so the combined result and action of the
various divisions of the quadriceps is to draw the patella more directly upwards.
If it were not for this arrangement, the contraction of the quadriceps would have
a strong tendency to produce outward dislocation of the knee-cap.
Relations of vastus externus, crureus, and vastus internus.-In front lie the
fascia lata, tensor vaginæ femoris, rectus femoris, and sartorius. To the inner side
lie the femoral vessels and anterior crural nerve. On the outer side are the gluteus
minimus and maximus. Behind are the biceps on the outer side of the femur, and
the adductor longus and magnus on the inner side.
Variations. These are few in number. An accessory head to the rectus from the anterior
superior spine of the ilium has been described, and occasionally the outer head is absent.
THE DEEP FASCIA OF THE LEG AND ANNULAR LIGAMENTS
The deep fascia of the leg is continuous above with the fascia lata of the thigh
and receives important additions from the tendons of the biceps, sartorius, gracilis,
and semi-tendinosus. It is also attached to the lower part of the outer and
inner tuberosities of the tibia and to the head of the fibula. At the back of the
knee it is strengthened by transverse fibres which serve to bind together the
muscles which form the boundaries of the popliteal space; the external saphenous
vein also perforates it about the centre of the space. It is very thick and strong
at the upper and outer part of the front of the leg; but behind, where it covers
the muscles of the calf, the fascia becomes much thinner. The internal surface
of the tibia is not covered by this fascia, which blends with the periosteum
covering its anterior and inner borders throughout their whole length. It is also
attached to the borders of the fibula by two strong intermuscular septa which form
the anterior and posterior walls of a compartment containing the long and short
peronei. In the lower third of the leg it is attached to the borders of the sub-
cutaneous surface of the fibula. In the neighbourhood of the ankle the deep fascia
is thickened by the addition of numerous transverse fibres, and forms the annular
ligaments.
The anterior annular ligament (fig. 298) consists of two parts, an upper and
a lower. The upper part is a strong band of transverse fibres just above the ankle
joint, which extends from the anterior border of the tibia to the anterior border of
the subcutaneous surface of the fibula. Behind it there is a separate synovial
sheath for the tendon of the tibialis anticus. The lower part of the anterior
annular ligament arises from the upper surface and outer border of the great
process of the calcaneum in two bands, a superficial and a deep, which, passing
transversely inwards, unite after a course of about an inch, and thus form a loop
in which are contained the tendons of the extensor longus digitorum and the
peroneus tertius, together with part of the origin of the extensor brevis digitorum.
From the inner extremity of this loop two bands of fibres of varying distinctness
proceed one passes upwards and inwards to join with the front border of the
internal malleolus; the other, which is usually the weaker, more directly inwards
over the scaphoid bone to join with the inner border of the plantar fascia. Beneath
GASTROCNEMIUS
391
this inner portion of the lower part of the anterior annular ligament the tendons
of the extensor proprius hallucis and tibialis anticus are contained in separate
synovial sheaths.
The external annular ligament passes from the posterior border of the external
malleolus to the outer border of the tuberosity of the calcaneum and to the posterior
part of the junction of the lower and outer surfaces of the calcaneum. It is con-
tinuous above with the deep fascia covering the calf muscles and the peronei;
and also with the sheet of fascia which separates the two superficial from the two
deeper layers of muscles at the back of the leg. Its deep surface is attached to the
peroneal tubercle on the outer side of the calcaneum.
The internal annular ligament extends from the posterior border of the internal
malleolus to the inner border of the tuberosity of the calcaneum. It is also
continuous above with the deep fascia of the leg and with the sheet of fascia which
intervenes between the soleus and the deeper sheets of muscle at the back of the leg.
MUSCLES OF THE BACK OF THE LEG
The muscles in this region are arranged in two layers above, in four below.
The first layer consists of the gastrocnemius and plantaris.

FIRST LAYER
1. GASTROCNEMIUS
The gastrocnemius-named from yaorýp the belly, and Kvýμn the calf, because
it forms the enlargement of that part of the leg-is double-headed, each head con-
sisting of a fusiform muscle, the lower part of which blends with its fellow so as to
form a common tendon of insertion. It forms the femoral origin of the great triceps
suræ muscle.
Origin. Outer head: a well-marked impression upon the upper and posterior
part of the outer surface of the external condyle and the adjacent part of the
posterior surface of the femur just above the external condyle.
Inner head: an oval impression placed transversely across the posterior
surface of the femur above the internal condyle, and reaching inwards to the back
of the adductor tubercle.
Insertion. By the tendo Achillis (so named from the legend that the heel, into
which this tendon is inserted, was the only vulnerable part of the hero Achilles)
into the lower part of the posterior surface of the calcaneum.
Structure. The two heads arise by short strong tendons; that of the inner is the
stronger and thicker. These tendons converge downwards towards one another, and
are succeeded by large fleshy expansions which unite at the upper part of the
middle third of the leg. Near this point the tendon of insertion begins as an inter-
muscular septum between the two bellies of the muscle. This becomes thicker and
stronger, and expands into a broad aponeurosis which covers the anterior surface of
the united muscle. Just below the middle of the leg the fleshy fibres terminate
upon the back of this aponeurosis in two curves the convexity of which is downwards,
that of the inner portion of the muscle descending about half an inch lower than the
outer. The strong aponeurosis becomes narrower and at the same time thicker,
392
THE MUSCLES
FIG. 291.-SUPERFICIAL MUSCLES OF THE BACK OF THE THIGH AND LEG.

Gluteus medius
Aponeurosis of gluteus
maximus
Biceps
Vastus externus
Plantaris
abredd
Gastrocnemius
ei
Foani food
Soleus
Gluteus maximus
Semi-membranosus
40 24192
Semi-tendinosus
Gracilis
Tendon of semi-membranosus
Sartorius
handsom
Peroneus longus
Flexor longus digitorum
Tendo Achillis

GASTROCNEMIUS-PLANTARIS
393
and after receiving the fibres of the soleus muscle is known by the name of the
tendo Achillis.
Nerve-supply. From the internal popliteal branch of the great sciatic nerve,
which sends sural branches to the adjacent portions of the anterior surfaces of the
two heads, in the upper third of the leg.
Action.-Its action will be described with that of the soleus, which forms a part
of the same muscle.
Relations.-Behind, the deep fascia, the external saphenous vein and nerve,
and the communicans fibularis nerve. Between the two heads above is the
plantaris muscle. In front lie the knee joint, the tendon of the semi-membranosus,
the popliteus, the plantaris tendon, the soleus, the popliteal vessels, and internal
popliteal nerve. On the outer side, above, are the biceps tendon, and external
popliteal nerve; on the inner side, above, are the tendons of the semi-tendinosus,
gracilis, sartorius, and adductor magnus. A bursa lies beneath its inner head,
separates it from the tendon of the semi-membranosus, and communicates with the
knee joint.
Variations. The most common variation is the addition of a third head from the
posterior surface of the lower end of the femur. This may cross, or even run between, the
popliteal vessels.
2. PLANTARIS
The plantaris-named from its occasional attachment to the fascia covering
the sole of the foot (=planta)-is a fusiform, somewhat flattened muscle with a
very long ribbon-shaped tendon.

-
Origin. (1) The lower two inches of the outer bifurcation of the linea aspera
together with the posterior surface of the femur immediately below that ridge;
and (2) the adjacent part of the posterior ligament of the knee joint.
Insertion. The inner side of the lower portion of the posterior surface of the
calcaneum; sometimes, however, it blends with the inner border of the tendo Achillis,
and sometimes it is continued into the inner division of the plantar fascia.
Structure.-Arising fleshy, the fibres of this small muscle have a somewhat
penniform arrangement and converge upon the thin tendon, which appears first on
the inner side of the muscle, and soon becoming free runs downwards and slightly
inwards across the calf between the gastrocnemius and the soleus. In the lower
third of the leg it lies along the inner border of the tendo Achillis, with which it is
sometimes blended.
Nerve-supply. From the internal popliteal branch of the great sciatic nerve by
a small filament which enters the deep aspect of the muscle near the upper part of
its inner border.
Action. This vestigial muscle is a feeble extensor of the ankle and flexor of
the knee joint. By its attachment to the posterior ligament of the knee joint it
will tend to draw backwards that ligament during flexion of the knee, and so
prevent its being caught between the articular surfaces.
Relations.-Behind lie the fascia of the popliteal space, the biceps, the gastro-
cnemius, and the external popliteal nerve; in front are the popliteal vessels and
internal popliteal nerve, the popliteus muscle and the soleus.
Variations. In addition to the above-mentioned variations in the point of insertion, this
muscle may sometimes be double at its origin, and it is not infrequently deficient.

394
THE MUSCLES
SECOND LAYER
The second layer is formed above by the popliteus, which is covered behind
by the aponeurosis derived from the semi-membranosus; and below by the soleus,
which is the lower head of the great triceps suræ muscle.
1. POPLITEUS
The popliteus (fig. 292)-named from its position on the floor of the ham
(=poples) is a triangular sheet.
Origin. The bottom of the anterior portion of a horizontal groove on the lower
part of the outer surface of the external condyle of the femur; also by a small slip
from the posterior ligament of the knee joint.
020
Insertion. (1) The back of the tibia from below the attachment of the pos-
terior ligament of the knee joint to the oblique line; (2) the fascia derived from
the tendon of the semi-membranosus, which covers the posterior surface of the
muscle.
Structure. Arising by a somewhat flattened cylindrical tendon which passes
at first backwards and slightly downwards within the knee joint, grooving the
posterior border of the external semilunar cartilage; it then escapes from the capsule
of the knee joint, receiving a small slip from the posterior ligament, and immediately
expands into a fan-shaped muscle which forms a thick sheet, covering the upper
fourth of the back of the tibia, and is inserted by fleshy fibres into the pouch formed
by the bone in front and the aponeurosis derived from the semi-membranosus behind.
The tendon of origin is surrounded by synovial membrane, which is reflected upon
it about half an inch beyond the opening, through which it emerges from the
posterior ligament of the knee joint.
Nerve-supply. From the sacral plexus by the internal popliteal division of the
great sciatic nerve, which sends a special branch round the lower border of the
muscle to distribute itself to the lower part of its deep or anterior surface.
Action. To flex the knee, which it will do but feebly on account of the obliquity
of its direction and its proximity to the axis of the joint. When the knee is flexed
it will act as an internal rotator of the leg. In this position the tendon of origin
lies wholly in the groove for its reception upon the outer surface of the external
condyle. It is possible that the attachment of the tendon of origin to the posterior
ligament of the knee may enable the muscle when it contracts to draw backwards
the ligament, and so prevent the synovial membrane upon its anterior aspect
from being nipped between the articular surfaces.
Relations. Behind, the aponeurosis of the semi-membranosus, the gastro-
cnemius, plantaris, and the popliteal vessels, nerves, and glands. In front, the
knee joint. Superficial to the tendon of origin is the external lateral ligament of
the knee.
Variations. A second head of origin has been seen from a sesamoid bone in the outer
tendon of the gastrocnemius.
2. SOLEUS
The soleus-named from solea, the Latin for a sole-fish, because of the resem-
blance of the muscle to this flat fish-is a thick, fusiform sheet.
-
Origin. (1) The oblique line of the tibia and the inner border of its posterior
surface, from the lower end of the oblique line to a little below the middle of the
SOLEUS
395
leg; (2) the back of the head and the upper third of the outer border of the
posterior or flexor surface of the fibula and the adjacent external intermuscular
septum; (3) a tendinous arch which stretches across the interval between the upper
part of the back of the tibia and fibula.
-
Insertion. By a strong aponeurosis which blends with the anterior surface of
the tendon of the gastrocnemius, and forms the tendo Achillis.
Structure. The muscle arises partly by fleshy fibres and partly by a strong
aponeurosis, which lies in front of the fleshy fibres, and is especially noticeable in
the neighbourhood of its tibial attachment. From the tibia and fibula the fibres
pass in a bipenniform arrangement downwards and towards the middle line, and
after a very short course, not exceeding two inches in length, they blend with
the tendon of insertion which begins near the upper part of the origin of the
muscles, and in cross-sections of the muscle resembles in shape the letter T; one
part of it forming a broad aponeurosis upon the posterior surface of the muscle,
the other part a strong tendinous septum which passes forwards from the middle
of the broad aponeurosis above mentioned, so as to separate the fleshy fibres into
two portions. About the junction of the middle and lower thirds of the leg, the
tendon of insertion joins by its posterior aspect with that of the gastrocnemius
muscle, but upon its anterior aspect and sides it receives fleshy fibres nearly
as far down as the back of the ankle joint. The tendo Achillis is a strong
rounded band of tendon about five-eighths of an inch from side to side, and three-
eighths of an inch from before backwards; it is narrowest at the level of the
ankle joint, and expands slightly before it is inserted into the lower part of the
posterior surface of the calcaneum. A bursa intervenes between the tendon and the
smooth upper part of the posterior surface of this bone.
Nerve-supply. From the internal popliteal division of the great sciatic nerve
by sural branches which enter the upper half of the muscle upon the posterior
surface; and lower down by a branch from the posterior tibial nerve, which enters
the anterior surface of the muscle.
Action. The chief action of the combined gastrocnemius and soleus is to extend
the ankle joint. It is an extremely powerful muscle, as it acts with considerable
mechanical disadvantage. The lever by means of which it acts may be best described
as one of the first order; the lever being that part of the foot which lies between
the heel and the heads of the metatarsal bones, the ankle being the fulcrum; a
pressure equal to the weight of the body being exerted by the ground at the anterior
extremity of the lever; and the arm, at the end of which the muscle acts, being the
comparatively short distance between the back of the heel and the centre of the
ankle joint. When the ankle joint has been completely extended, this muscle will
tend to adduct slightly the foot, and to invert the sole, this movement being carried
out in the joint between the astragalus and calcaneum. Besides extending the ankle,
the gastrocnemius will assist in flexing the knee joint. The chief object, however,
which appears to be gained by the femoral attachment of this muscle is the addition
to the rapidity of extension of the foot. Like some of the other long muscles which
pass over two joints, the gastrocnemius, if it were an inextensible ligament, would
cause extension of the ankle as soon as the knee was straightened by means of the
great quadriceps muscle. Seeing, however, that during the contraction of the
quadriceps the gastrocnemius is at the same time acting, it follows that the rapidity
and amount of the extension of the ankle joint is almost doubled. By these means
we obtain that rapid and powerful contraction which gives the spring to the body
in leaping and running. We may see also how enormously strong the tendon
Achillis must be, as it has not only to bear the contraction of the gastrocnemius and
soleus, but the additional strain thrown upon it by the simultaneous action of the
quadriceps extensor of the knee. The soleus will assist in the extension of the
ankle, and will even be able to perform this movement somewhat feebly by itself,

396
THE MUSCLES
when in extreme flexion of the knee joint the gastrocnemius is so relaxed as to be
almost powerless. It is much stronger than the gastrocnemius, as may be inferred
from the enormous number of short fibres by which it is formed. At the same
time, however, as it only passes over the ankle and calcaneo-astragaloid joints, the
range of its movements is very short.
Variations. A second soleus is sometimes formed beneath the normal muscle, and
more or less separate from it. It is usually inserted into the calcaneum or internal
annular ligament.
THIRD LAYER
The third layer is separated from the superficial layers by an aponeurosis called
the deep tibial fascia. This is attached to the inner border of the tibia internally,
and externally to the outer border of the flexor surface of the fibula, and the
posterior of the two external intermuscular septa. It is thin above, but below it
is strengthened by transverse fibres, and becomes much thicker. At the ankle
it blends with the deep fascia of the leg and the external and internal annular
ligaments. The third layer consists of two muscles-the flexor longus digitorum
and the flexor longus hallucis.
1. FLEXOR LONGUS DIGITORUM
The flexor longus digitorum-named from its being the longer of the two flexors
of the toes-is a fusiform sheet.
—
Origin. (1) The inner part of the posterior surface of the tibia, beginning with
the lower half of the oblique line, and ending about three inches above the inner
ankle; (2) the front of the deep fascia which covers the sheet; (3) a thin inter-
muscular septum which intervenes between this muscle and the tibialis posticus.
Insertion. The under surface of the base of the ungual phalanx of each of
the four outer toes.
Structure.-Arising fleshy from the tibia and adjacent fasciæ, the fibres pass in
a penniform manner into the front and outer side of a tendon which, beginning
about the middle of the leg, gradually becomes thicker and stronger, and receives its
last fleshy fibres about two inches above the ankle joint. It then passes beneath
the internal annular ligament in a compartment posterior and external to that for
the tibialis posticus. Thence it runs downwards, forwards, and outwards beneath
the first layer of the sole muscles, and, after having received fleshy fibres from the
accessorius pedis and a small tendinous slip from the tendon of the flexor longus
hallucis, divides, about half-way between the tuberosity of the calcaneum and the
heads of the metatarsal bones, into four tendons. These enter the thecæ of the
four outer toes, and each tendon passes through the splitting of the tendon of
the flexor brevis digitorum to its insertion upon the under surface of the base of
the third phalanx. The lumbricales arise from its tendons in the sole of the foot.
Nerve-supply. From the posterior tibial nerve by branches which enter the
superficial aspect of the muscle near its outer border about the middle of the leg.
Action.-To flex the last phalanges of the four outer toes; it will then help to
flex the second and first phalanges and the medio-tarsal joint of the foot. It will
also help slightly in the extension of the ankle joint. In flexing the medio-tarsal
joint, it will tend to preserve the arch of the instep.
Relations. Superficially, in the leg the soleus, posterior tibial vessels and
nerve; in the foot, the abductor hallucis and flexor brevis digitorum. Deeply, lie
the tibialis posticus in the leg, and in the foot the tendon of the flexor longus
hallucis, the accessorius, and the muscles which form the third layer of the sole of
the foot.


FLEXOR LONGUS DIGITORUM
397
Variations. An accessory head sometimes arises in the leg from the fibula, the tibia, or
the deep fascia of the leg; it may join the rest of the muscle in the leg, or in the sole.
FIG. 292. THE DEEP MUSCLES OF THE BACK OF THE LEG.

Plantaris
Outer head of gastrocnemius
Inner head of gastrocnemius
Biceps
Tendon of semi-membranosus
Popliteus
Tibialis posticus
Peroneus longus-
Flexor longus digitorum
Flexor longus hallucis
Peroneus brevis.
Tibialis posticus
Tendo Achillis
Some of the tendons to the toes may be wanting; more often they are increased in
number and supply the deficiencies of the flexor brevis digitorum, and especially by sending
slips to the little toe.

398
THE MUSCLES
2. FLEXOR LONGUS HALLUCIS
The flexor longus hallucis-named from its action upon the great toe (hallux)
and its length-is a strong fusiform sheet.
Origin. The lower two-thirds of the postero-internal (or flexor) surface of the
fibula external to the oblique line; (2) the intermuscular septa between it and the
tibialis posticus in front, and the peronei outside; (3) the deep fascia covering
its posterior surface; (4) the lowest portion of the interosseous membrane.
Insertion.-(1) The under surface of the base of the last phalanx of the great
toe; (2) by a small slip into that part of the flexor longus digitorum tendon which
is distributed to the second and third toes.
Structure. The muscle arises by fleshy fibres which pass with a bipenniform
arrangement into the tendon. This tendon appears first just below the middle of
the leg at the back of the muscle near its inner border. The fleshy fibres are
inserted into it as far as the ankle joint, and just above this point the tendon passes
through the groove at the outer part of the back of the lower end of the tibia.
The tendon then grooves the back of the astragalus, and afterwards the under
surface of the sustentaculum tali, where it lies external to the tendon of the
flexor longus digitorum. From this point it passes forwards in the second layer
of the muscles of the sole, lying above and crossing the tendon of the flexor longus
digitorum, to which it gives a small slip. It then crosses beneath the inner head
of the flexor brevis hallucis, lies in the groove between the sesamoid bones of
that muscle, and is finally inserted into the base of the last phalanx.
Nerve-supply. From the posterior tibial nerve by branches which enter the
muscle in the upper part of its posterior surface near its inner border.
Action. This muscle, which is much more powerful than the flexor longus
digitorum, is a strong flexor of the last phalanx of the great toe, and is of great
importance in walking, as it presses the great toe firmly against the ground. The
ungual phalanx of the great toe is the last part of the foot to leave the ground when
the step is completed; and until this is the case the flexor longus hallucis is strongly
contracted. It will also help to flex the first phalanx of the great toe upon its
metatarsal bone and it will act upon the joints which intervene between the first
metatarsal bone and the astragalus; and, finally, it will assist in the extension of
the ankle joint.
-
Relations. Superficially, in the leg, it is covered by the soleus, and in the foot
by the abductor hallucis, the flexor longus digitorum, the external plantar vessels
and nerve; on its outer side are the peronei; on its deep aspect in the leg lie the
tibialis posticus and the peroneal vessels; and, after passing over the back of the
ankle and other joints, it lies upon the inner head of the flexor brevis hallucis.
Variations.-An accessory portion of the muscle may be inserted into the sustentaculum
tali or the inner surface of the calcaneum. The slip to the flexor longus digitorum tendon
may vary in the number of toes to which it is distributed.
FOURTH LAYER
The fourth layer consists of one muscle-the tibialis posticus.
TIBIALIS POSTICUS
The tibialis posticus-named from its position in the back part of the leg and
its origin from the tibia-is a thick fusiform sheet.
Origin. (1) The whole of the back of the interosseous ligament with the exception
of the lowest portion; (2) the posterior surface of the tibia close to the interosseous
line, from the upper end of the oblique line to the junction of the middle and lower
TIBIALIS POSTICUS
399
thirds of the shaft; (3) the antero-internal (or inner part of the flexor) surface of
the fibula at the back of the interosseous ridge to within an inch or two of the
ankle; (4) the intermuscular septa which intervene between it and the muscles of
the third layer, viz. the flexor longus hallucis and the flexor longus digitorum; and
(5) a small portion of the deep fascia covering the back of the third layer.
Insertion. (1) The tuberosity of the scaphoid bone; (2) by several smaller
offsets into the front of the lower surface of the sustentaculum tali and the under
surface of all the other tarsal bones with the exception of the astragalus; and (3)
the under surface of the bases of the second, third, and fourth metatarsal bones.
Structure. A strong bipenniform muscle, the central tendon of which, lying
upon the middle of the back of the muscle, begins about the middle of the leg, and
passes downwards and inwards upon the back of the muscle, receiving its last fleshy
fibres about an inch above the ankle. Having passed inwards beneath the tendon
of the flexor longus digitorum, it enters the innermost groove on the back of the
internal malleolus, and is contained in a synovial sheath which accompanies it to its
insertion upon the scaphoid bone. From this insertion strong fibrous bands radiate
backwards, outwards, and forwards to the tarsal and metatarsal bones, being inti-
mately blended with the ligaments by which these bones are held together. This
muscle, which is very strong, is contained, so to speak, in a four-sided prismatic case
formed in the front by the interosseous membrane; at the sides, by the opposing
surfaces of the tibia and fibula; and behind, at a distance of nearly half an inch from
the interosseous membrane, by the intermuscular septa which separate the muscle
from the flexor longus hallucis and the flexor longus digitorum.
Just above its insertion into the tuberosity of the scaphoid bone, the tendon
often contains a sesamoid bone.
Nerve-supply. From the posterior tibial, which sends branches forwards to
the back of the muscle in the upper third of the leg.
Action.-(1) To adduct the front of the foot; (2) to invert the sole; (3) to
extend the ankle-the last of these movements is somewhat limited; (4) to
support the longitudinal arch of the foot-firstly, by drawing backwards the lower
part of the scaphoid, and so preventing the descent of the head of the astragalus
between the scaphoid and calcaneum, and secondly by its traction upon the other
tarsal bones upon which the secondary offsets of its tendon are inserted.
Relations. Superficially, the soleus and third layer of muscles of the leg, the
posterior tibial and peroneal vessels and the posterior tibial nerve above; the
tendon of the flexor longus digitorum and the abductor hallucis below; deeply,
the ankle joint and inferior calcaneo-scaphoid ligament. The anterior tibial vessels
pass through a notch at the upper extremity of the muscle, between its tibial and
fibular origins.


THE FASCIA AND MUSCLES OF THE SOLE
OF THE FOOT
The plantar fascia is, like the corresponding fascia in the palm, very strong, and
is divided into three parts. The central part, which is the strongest, arises from
the under surface of the calcaneum at the back of the tubercles. It is triangular
in shape and expands forwards to its attachment at the base of the toes, where
it splits into five divisions. Each division forms an arch over the tendons entering
the toe, and is continuous with the ligamentum vaginale of the theca. The sides of
the arch pass upwards to be attached to the deep transverse ligament which

400
THE MUSCLES
connects the heads of the metatarsal bones and to the lateral ligaments of the
metatarso-phalangeal joints. The under surface of the fascia is attached to the deep
surface of the skin by small fibrous bands which form the walls of compartments
containing pellets of fat. These fibrous connections give firmness to the skin of the
sole and prevent it from being moved about upon the subjacent fascia. The borders
of the central portion of the plantar fascia are continued upwards into the sole by the
internal and external intermuscular septa, which are attached above to the fibrous
structures on the under surface of the tarsal bones. The inner portion, which is the
thinnest division of the plantar fascia, is, attached behind to the inner border of the
FIG. 293.-FIRST LAYER OF THE MUSCLES OF THE SOLE.
Flexor brevis digitorum
Abductor minimi digiti-
Abductor hallucis
-Flexor longus hallucis
Flexor brevis minimi digiti-
-Flexor brevis hallucis
First lumbricalis
Tendon of flexor longus-
digitorum
Tendon of adductor hallucis
410
great tubercle of the calcaneum and to the lower border of the internal annular
ligament. It is inserted in front upon the inner side of the base of the first phalanx
of the great toe, and above it becomes continuous with the deep fascia covering the
instep. The external portion is very thick, and arises from the outer border of the
lesser tubercle of the calcaneum and the lower border of the external annular
ligament. It terminates in front in the base of the first phalanx of the little toe,
and at its inner border it blends with the central portion of the plantar fascia,
where it is joined by the external intermuscular septum, and upon its outer border
it is closely connected with the base of the fifth metatarsal bone, and it is
continuous with the deep fascia covering the instep.
ABDUCTOR HALLUCIS-FLEXOR BREVIS DIGITORUM
401
In the web between the toes some thin transverse fibres are found, the superficial
transverse ligament of the toes. They bridge over part of the interval between
the five slips into which the front part of the central division of the plantar fascia
breaks up.
The muscles and tendons in the sole of the foot are divided into four layers.
The first layer consists of three muscles, which correspond in their position to the
three compartments formed by the plantar fascia and the two intermuscular septa,
viz. the abductor hallucis, the flexor brevis digitorum, the abductor minimi digiti.
FIRST LAYER
1. ABDUCTOR HALLUCIS
The abductor hallucis-named from its action upon the great toe-is a thick
triangular sheet, with a broad origin behind, which is divided into two heads.
Origin. Outer head: (1) The front and inner surfaces of the inner or greater
tubercle on the under surface of the calcaneum; (2) the deep surface of the inner
portion of the plantar fascia; (3) the intermuscular septum which separates it
from the flexor brevis digitorum. Inner head: (1) The deep aspect of the lower
border of the internal annular ligament; (2) the under surface of the attachment
of the tendon of the tibialis posticus to the tuberosity of the scaphoid bone and the
adjacent prolongations of this tendon.
Insertion. The inner part of the lower surface of the base of the first phalanx
of the great toe and the inner side of the internal sesamoid bone. Occasionally,
also, the inner border of the expansion of the extensor proprius hallucis on the
back of the first phalanx.
Structure.-The outer head arises in close connection with the flexor brevis
digitorum by short tendinous fibres, soon succeeded by a divergent fleshy bundle
which is joined about two inches from its origin by the fleshy sheet formed by the
inner head. The tendon to which these fleshy fibres converge appears first upon
the inner and lower aspect of the muscle, and receives fleshy fibres nearly to its
insertion, which is closely blended with that of the inner portion of the flexor brevis
hallucis. The deep surface of the muscle arises from a fibrous arch attached on
the one side to the septum between it and the flexor brevis digitorum; on the other
side to the tibialis posticus tendon and the fibrous tissue covering the under surface
of the tarsal bones along the inner border of the foot. Through this arch pass
the plantar vessels and nerves.
Nerve-supply. The internal plantar division of the posterior tibial nerve, by
filaments which enter the deep surface of the middle of the muscle.
Action.-(1) To flex the first phalanx upon the metatarsal bone; (2) to abduct
from the middle line of the foot the first phalanx of the great toe.
Relations.- Superficially, the internal division of the plantar fascia; upon its
outer border, the flexor brevis digitorum; deeply, the tendons of the tibialis
anticus, tibialis posticus, flexor longus digitorum, flexor longus hallucis, the plantar
vessels and nerves.
Variations. A third head is occasionally derived from the deep surface of the skin
upon the inner border of the foot, or from the long plantar ligament. The muscle may give
a slip to the second toe.


2. FLEXOR BREVIS DIGITORUM
The flexor brevis digitorum pedis, or flexor perforatus-named from its being
the shorter of the flexors of the four outer toes-is a triangular sheet, divided in
front into four processes corresponding to the tendons of the toes.
DD

402
THE MUSCLES
Origin. (1) The outer part of the front of the lower surface of the great
tubercle of the calcaneum; (2) the deep surface of the back part of the central
portion of the plantar fascia; (3) the back part of the intermuscular septa on either
side.
Insertion. The sides of the middle phalanx of each of the four outer toes upon
its plantar aspect.
Structure. Arising tendinous by a pointed process from the under surface of
the great tubercle, the fleshy fibres extend in a fan-shaped sheet, which, about half-
way between the origin and the heads of the metatarsal bones, divides into four fleshy
processes which soon become tendinous. The tendons are arranged in a similar
manner to those of the flexor sublimis digitorum in the hand. After splitting
beneath the first phalanx of the toe, the two halves of the tendon pass round the
sides of the flexor longus digitorum tendon, and about the level of the base of the
second phalanx they unite by their adjacent margins, and again diverge to be
attached to the sides of the plantar surface of the second phalanx.
Nerve-supply. From the internal plantar division of the posterior tibial, by
branches which enter the back of the deep aspect of the muscle near its inner
border.
Action. This muscle, which is comparatively feeble, will flex the second
phalanges of the toes, and in combination with the flexor longus digitorum it
will assist in walking, by pressing the under surface of the phalanges of the toes
against the ground. After it has flexed the second phalanges, it will act in a
similar manner upon the metatarso-phalangeal and medio-tarsal joints.
Relations. Superficially, the plantar fascia; on either side, the other muscles of
the first layer of the sole; deeply, the tendon of the flexor longus digitorum and
the lumbricales, the accessorius muscle, and the external plantar vessels and nerve.
Variations. The part of the muscle which belongs to the little toe is often absent, and
its place may be supplied by a small perforated slip from the tendon of the flexor longus
digitorum.
3. ABDUCTOR MINIMI DIGITI

The abductor minimi digiti (pedis)-named from its action upon the fifth and
smallest toe-is a thick triangular sheet, partly muscular and partly aponeurotic.
Origin. (1) The outer side and the under surface of the front of the lesser
tubercle of the calcaneum and the adjacent portion of the under surface of that
bone in front of the great tubercle; (2) the upper surface of the back part of
the outer division of the plantar fascia; (3) the outer surface of the back part of
the external intermuscular septum; (4) the long plantar ligament and other liga-
mentous structures lying upon the outer border of the sole, and more especially
an aponeurotic band which runs from the outer side of the lesser tubercle of the
calcaneum to the outer side of the base of the fifth metatarsal bone, and of the base
of the first phalanx of the fifth toe.
Insertion. (1) The outer part of the under surface of the base of the first
phalanx of the little toe; (2) usually also the outer part of the under surface of
the base of the fifth metatarsal bones; (3) the outer edge of the fourth tendon of
the extensor longus digitorum upon the back of the first phalanx of the little toe.
A
Structure. The muscle, which is at first encased in the aponeuroses, from
which as well as from the bone it takes origin, converges from both sides upon a
tendon which is first visible on its under surface at the front of the calcaneum.
small portion of its outer part is now inserted into the tubercle of the fifth
metatarsal bone, internal to the strong aponeurotic band which is also here attached.
From this point the tendon of insertion is free on its inner side, but receives fleshy
ABDUCTOR MINIMI DIGITI
403
fibres still from the continuation of the aponeurotic band just mentioned, until it
is inserted into the base of the first phalanx.
Nerve-supply. From the external plantar division of the posterior tibial nerve,
by filaments which enter the back part of the deep surface of the muscle near its
inner border.
Action.-(1) To abduct the first phalanx of the little toe from the middle line;
(2) to flex the metatarso-phalangeal joint of the little toe.
The usual action of the muscle will be a combination of these two movements.
Relations. Superficially, the plantar fascia, the flexor brevis digitorum, and
FIG. 294.-SECOND LAYER OF THE MUSCLES OF THE SOLE.

Flexor brevis digitorum
Origin of abductor minimi digiti
Abductor hallucis
Part of abductor minimi digiti
Accessorius
Flexor longus digitorum
Flexor longus hallucis
Flexor brevis minimi
digiti
Flexor brevis hallucis
Abductor minimi digiti-
Adductor hallucis
Abductor hallucis
Lumbricales.
Tendon of flexor brevis
digitorum
even a small portion of the abductor hallucis. Deeply, the accessorius, flexor
brevis minimi digiti, long plantar ligament, and peroneus longus tendon.
Variations. The muscular slip attached to the base of the fifth metatarsal bone is often
so distinct as to form a separate muscle, the abductor ossis metatarsi quinti.
SECOND LAYER
The second layer consists of the flexor accessorius muscle, the four lumbricales,
and the tendons of the flexor longus hallucis and the flexor longus digitorum.
DD 2
404
THE MUSCLES
1. FLEXOR ACCESSORIUS DIGITORUM PEDIS
The flexor accessorius digitorum pedis named from its accessory or supple-
mentary action in assisting the flexion of the toes by the flexor longus digitorum-
is a double-headed quadrilateral sheet.
A
Origin. Inner head: The whole of the concave inner surface of the calcaneum
below the groove for the flexor longus hallucis.
Outer head: (1) The junction of the lower and outer surfaces of the calcaneum
in front of the lesser tubercle; (2) the under surface of the back part of the long
plantar ligament.
Insertion. The upper surface and outer border of the flexor longus digitorum
tendon about midway between the tubercles of the calcaneum and the heads of the
metatarsal bones.
Structure. Its inner head consists of fleshy fibres which converge from their
origin in a somewhat fan-shaped sheet, and are joined shortly before their insertion
into the tendon by the outer head, which consists of a pointed tendinous origin,
from which the fleshy fibres form a somewhat smaller fan-shaped sheet which
blends with that from the inner head, to be inserted by fleshy fibres upon the upper
surface and outer border of the flexor longus digitorum, at its point of division
into the tendons for the four outer toes.
Nerve-supply. From the external plantar division of the posterior tibial nerve,
by branches which enter the under surface of the muscle near its origin.
Action.-To help in the flexion of the last phalanges of the four outer toes,
and at the same time to draw the toes somewhat outwards. On account of the
oblique direction of the tendons of the flexor longus digitorum in the foot, they
would tend in flexing the toes to draw them at the same time inwards. This
tendency will be somewhat neutralised by the simultaneous contraction of the
accessorius. The accessorius will also be able to flex the toes when, on account of
the extension of the ankle joint, the muscular fibres of the flexor longus digitorum
are so relaxed as to be incapable of action.
Relations. Superficially, the tendons of the flexor longus digitorum and
flexor longus hallucis, with the external plantar vessels and nerve; deeply, the
flexor brevis hallucis and long plantar ligament.
Variations. An additional head may arise above the ankle from the flexor longus
digitorum, flexor longus hallucis, or soleus. Sometimes the outer head is wanting, and
occasionally the whole muscle is absent. The distribution of its fibres to the tendons of
the long flexor is very variable. It may send fibres to the tendon of the flexor longus
hallucis.

2. THE FOUR LUMBRICALES
1
The four lumbricales-named from their shape (lumbricus = an earthworm)-
are, like those in the palm, four small fusiform muscles.
Origin. The first, from the inner border of the innermost tendon of the flexor
longus digitorum, from the point of division of the main tendon for about an inch
forwards; the other three, from the adjacent surfaces of the tendons of the first
and second, the second and third, and the third and fourth tendons of the flexor
longus digitorum on their plantar aspect.
Insertion. The inner border of the expansion of the extensor longus digitorum
tendon upon the back of the first phalanx of each of the four outer toes.
Structure. The origin of the muscle is entirely fleshy. It ends in a small
rounded tendon a short distance above the web of the toes. This tendon runs
forwards and upwards upon the inner side of its toe, above the superficial transverse
LUMBRICALES-FLEXOR BREVIS HALLUCIS
405
ligament of the toes and beneath the deep transverse ligament of the metatarsus,
to the side of the expansion of the extensor tendon.
Nerve-supply. The two inner are supplied by the internal plantar division of
the posterior tibial nerve, by filaments which enter the back part of the lower
surface of each muscle near its inner border; the two outer, by the external
plantar nerve, by filaments which enter the deep part of each muscle near its
outer border.
Action. (1) To flex the first phalanx of the toe; (2) to straighten the second
and third phalanges. (3) The first will abduct the second toe from the axis
passing through it, which is looked upon as the middle line of the foot. The three
others will adduct. The lumbricales will be able to act upon the first phalanges,
even when the second and third have been flexed by means of their special flexors.
The chief advantage derived from the simultaneous extension of the two terminal
phalanges and the flexion of the first phalanx is the application of the whole length
of the toe to the ground in walking; otherwise there would be a strong tendency
to the flexion of the phalanges of the toes, which would prevent the proper
application of the soft plantar aspect of the ungual phalanx to the ground.
Relations. Superficially, the flexor brevis digitorum. Deeply, the flexor longus
digitorum tendons, the transversalis pedis, and the interossei.
THIRD LAYER
The third layer consists of four muscles-the flexor brevis hallucis, the adductor
hallucis, the transversus pedis, and the flexor brevis minimi digiti.

1. FLEXOR BREVIS HALLUCIS
The flexor brevis hallucis, or flexor brevis pollicis pedis-named from its
action, and its size in comparison with the other flexor of the great toe-is a thick
triangular sheet with a forked insertion.
Origin. (1) The plantar ligaments and the continuations of the tibialis
posticus tendon in the middle of the sole; (2) the inner part of the under surface
of the cuboid bone.
Insertion. The inner and outer borders of the plantar aspect of the base of the
first phalanx of the great toe.
Structure.-Arising fibrous by a pointed process in the middle of the sole, the
fibres diverge as they pass forwards and slightly inwards, and form two fleshy
bundles of equal size, which are succeeded by short tendons. In each tendon is
contained a sesamoid bone of ovoid shape about three-eighths of an inch in the long
antero-posterior diameter, and a quarter of an inch from side to side, with a
cartilaginous articular facet upon the upper surface which plays upon the lower
surface of the condyles of the first metatarsal bone. At their insertion into the inner
and outer part of the lower border of the base of the first phalanx, they are blended
with the tendons of the abductor and the adductor hallucis.
Nerve-supply. From the internal plantar division of the posterior tibial nerve,
by filaments which enter the under surface of the muscle near the middle of its
inner border.
od to
Action. To flex and slightly adduct the first phalanx of the great toe. The
sesamoid bones give a slight obliquity to its insertion, and so enable it to act with
more power; at the same time they form a groove in which the strong tendon of
the flexor longus hallucis plays. They also form a somewhat elastic support when
the weight is placed upon the ball of the foot.
Relations.-Superficially, the abductor hallucis, the tendon of the flexor longus



406
THE MUSCLES
hallucis, and the inner tendons of the flexor longus digitorum with the lumbricales;
deeply, the interossei and the termination of the external plantar vessels and nerve.
Variations. A small slip is occasionally given to the first phalanx of the second toe.
2. ADDUCTOR HALLUCIS
The adductor hallucis-named from its action upon the great toe-is a triangular
sheet, the apex of which is directed forwards and inwards.
FIG. 295.-THIRD LAYER OF THE MUSCLES OF THE SOLE.
Flexor longus hallucis
Part of abductor minimi
digiti
Flexor longus digitorum
Tibialis posticus
Flexor brevis minimi digiti
Flexor brevis hallucis
Transversus pedis
Adductor hallucis
Origin. (1) The continuation forwards of the long plantar ligament which
forms the sheath of the peroneus longus tendon; (2) the under surface of the
bases of the second, third, and fourth metatarsal bones.
Insertion. The outer part of the under surface of the base of the first phalanx
of the great toe.
Structure. Arising by short tendinous fibres, the muscle converges in bipenni-
form fashion upon a short tendon, which blends with that of the flexor brevis
hallucis and the outer sesamoid bone internally, and the transversus pedis
externally.
ADDUCTOR HALLUCIS-FLEXOR BREVIS MINIMI DIGITI 407
Nerve-supply. From the external plantar division of the posterior tibial nerve
by filaments which enter the upper surface of the muscle upon its outer border
near its origin.
Action. (1) To adduct the first phalanx of the great toe towards the middle
line of the foot; (2) to flex the first phalanx. Usually it will act during walking
in combination with the flexor brevis hallucis and abductor hallucis, and the
three muscles contracting together will produce direct flexion of the first phalanx,
so that when the weight of the body rests upon the front part of the foot the
second phalanx is pressed firmly against the ground by the action of the flexor
longus hallucis, while the first phalanx is acted upon in the same manner by the
combination of these three short muscles. As Duchenne has pointed out, the
abductor and adductor will have an important function in adjusting the pressure
when the step has to be made upon uneven ground. Thus, in walking upon
a slope the adductor hallucis of the one foot will direct the pressure downwards
and slightly outwards, while the abductor of the other foot will direct the pressure
downwards and slightly inwards.
Relations. Superficially, the flexor longus digitorum tendons and their lumbri-
cales; deeply, the interossei with the external plantar vessels and nerve; at the
sides, the flexor brevis hallucis and transversus pedis.
Variations. The adductor hallucis sometimes sends a slip to the first phalanx of the
second toe.

3. TRANSVERSUS PEDIS
The transversus pedis-named from the direction of its fibres-is a small
muscle consisting of three or four fusiform bundles lying side by side, and uniting in
a single tendon.

-
Origin. (1) The plantar ligaments of the three outer metatarso-phalangeal
joints; (2) the under surface of the adjacent deep transverse metatarsal ligaments.
Insertion. The outer side of the base of the first phalanx of the great toe.
Structure. The fleshy fibres form a series of small bundles which converge
slightly as they pass inwards and slightly forwards, and after uniting terminate in
a short tendinous insertion which is closely blended with the outer surface of the
tendon of the adductor hallucis.
Nerve-supply. From the external plantar division of the posterior tibial nerve
by filaments which pass to the upper part of the posterior edge of the muscle.
Action. (1) To adduct the first phalanx of the great toe; (2) to draw together
the heads of the metatarsal bones after they have been separated by the pressure
of the weight of the body during the tread.
Relations. Superficially, the flexor longus digitorum tendons and lumbricales;
deeply, the interossei.
Variations. Some or all of the bundles may be absent; most frequently the outermost
one. Occasionally fibres join the muscle from the fascia covering the interossei below
the lower border of the adductor hallucis, so that the two muscles are more or less blended.
4. FLEXOR BREVIS MINIMI DIGITI
The flexor brevis minimi pedis digiti-named from its action upon the little
toe-is small, flattened, and fusiform.
Origin. (1) The under surface of the base of the fifth metatarsal bone; (2) the
adjacent part of the sheath of the peroneus longus tendon.
Insertion. (1) The outer part of the under surface of the base of the first phalanx
of the little toe; (2) the outer part of the front of the under surface of the fifth
metatarsal bone.
408
THE MUSCLES
Structure.-Arising tendinous, the fleshy fibres run forwards and a little out-
wards to their short tendon of insertion, which is closely blended with that of the
abductor minimi digiti. A few of the deeper fibres end in the metatarsal bone.
Nerve-supply. From the external plantar nerve by a branch which enters the
under surface of the muscle.
Action. To flex and slightly abduct the first phalanx of the little toe.
Relations. Superficially, the flexor longus digitorum and abductor minimi
digiti; deeply, the interossei of the outermost interspace.
Variations. The insertion upon the metatarsal bone may form a separate muscle, the
opponens digiti pedis quinti, or it may be entirely absent.
FOURTH LAYER
The fourth layer consists of the seven interosseous muscles.
INTEROSSEI
enoitalsЯ
The interossei-named from their position between the metatarsal bones-are,
like those of the hand, seven in number, three being plantar and four dorsal.
The plantar are small and narrow fusiform bundles; the dorsal are bipenniform
and of a somewhat broader fusiform shape than the plantar. The interossei of
the foot differ from those of the hand in the fact that they adduct and abduct with
respect to a longitudinal axis through the line of the second toe; whereas in the
hand the median line passes through the middle finger.
The plantar interossei. Origin. (1) The inner and lower surface of the three
outer metatarsal bones; (2) the adjacent part of the sheath of the peroneus longus
tendon.
Insertion. (1) The inner side of the bases of the first phalanges of the three
outer toes; (2) the inner border of the expansions of the long extensor tendons on
the back of the first phalanges of the same toes.
The dorsal interossei arise from the adjacent surfaces of the metatarsal bones
bounding each interosseous space. The first dorsal interosseous, however, differs
somewhat in its internal head, which is from the base only of the first metatarsal
bone and the adjacent outer surface of the internal cuneiform bone.
Insertion. The first dorsal interosseous is inserted into :-(1) the inner side of
the base of the first phalanx of the second toe; (2) the inner edge of the aponeurosis
of the extensor tendon upon the back of the first phalanx. The second, third and
fourth are inserted respectively into: (1) the outer side of the bases of the first
phalanges of the second, third, and fourth toes; (2) the outer border of the extensor
tendons upon the backs of the same phalanges.
Structure. The plantar interossei are penniform muscles consisting of fleshy
fibres which run forwards to the outer side of a tendon which begins about the
middle of the space and becomes free opposite the heads of the metatarsal bones.
The dorsal interossei are bipenniform, and consist of fleshy fibres which con-
verge from both sides of the space upon a central tendon which begins about the
middle of the interosseous space and becomes free opposite the heads of the meta-
tarsal bones. The tendons of both sets of muscles before their insertion lie above
the deep transverse metatarsal ligament which separates them from the tendons
of the lumbricales. On the back of the foot the dorsal interossei are alone visible
in the sole of the foot both sets are seen. se od do dreads adv
Nerve-supply. From the external plantar nerve by filaments which enter the
plantar aspect of the muscles, somewhat behind the middle of the interosseous
space.
-
;
INTEROSSEI
409
Action.-The common action of all the interossei is (1) to flex the first phalanges
of the four outer toes; (2) to extend the second and third phalanges. In these two
movements they are assisted by the lumbricales. In walking, this movement is of
great importance as it keeps the toes straight when the weight of the body rests
upon the front part of the foot. When these movements are paralysed, the action
of the long and short flexor of the toes is to curl them up, and the ends of the toes
will be subjected to considerable pressure, which may set up inflammation to the beds
of the nails.
•
FIG. 296.-FOURTH LAYER OF THE MUSCLES OF THE SOLE.

Peroneus longus.
Plantar interossei
T
ambitne allaidit T
sdi la (I might
qoof
Dorsal interossei
ancitalo
The special action of the plantar interossei is to adduct the first phalanges of
the three outer toes; and of the dorsal interossei to abduct the second, third, and
fourth toes from the middle line of the second toe. As the second toe can be
abducted from its own middle line in two directions, it of course requires two
abductors.
Relations. On the plantar surface both sets of interossei are in contact with the
muscles of the third layer, and with the external plantar vessels and nerve; on the
dorsal surface the dorsal interossei are covered by the tendons of the extensor
longus and brevis digitorum. The dorsalis pedis and other perforating arteries
pass through the back of the interosseous spaces between the double origins of the
dorsal interossei.
32

410
THE MUSCLES
MUSCLES OF THE FRONT OF THE LEG
Between the anterior border of the tibia and the anterior of the two external
intermuscular septa, are placed four muscles: the tibialis anticus, the extensor
proprius hallucis, the extensor longus digitorum, and the peroneus tertius.
1. TIBIALIS ANTICUS
The tibialis anticus-named from its attachment to the tibia and its position
in the front of the leg-is fusiform and somewhat flattened, with a long terminal
tendon.
Origin. (1) Part of the under surface of the outer tuberosity of the tibia; (2)
the outer surface of the upper two-thirds of the tibia; (3) the adjacent part of the
anterior surface of the interosseous membrane; (4) the posterior surface of the
upper part of the deep fascia of the leg; (5) an intermuscular septum which separates
it from the extensor longus digitorum in the upper third of the leg.
Insertion. The lower part of the front of the inner surface of the internal
cuneiform bone and the adjacent part of the base of the first metatarsal bone.
Structure. A strong penniform muscle the fibres of which, arising fleshy from
the bone and from the strong fasciæ, pass forwards and most of them somewhat
outwards to be attached to the deep surface and outer border of a tendon, which,
beginning below the middle of the leg, becomes free of fleshy fibres two or three
inches above the ankle-joint; and, after passing first beneath the upper portion of
the anterior annular ligament, then partly under and partly over the lower portion,
expands slightly to be inserted upon the inner margin of the foot. In passing over
the instep it turns upon itself so that its anterior surface becomes below internal.
Nerve-supply. From the anterior tibial division of the external popliteal nerve
by branches which enter the upper third of the muscle upon the outer part of its
deep aspect.
Action.-(1) To flex the ankle joint; (2) to draw upwards the inner border of
the foot and so invert the sole; (3) to adduct the front portion of the foot. The
first of these movements will be performed chiefly in the ankle joint; the second
and third in the medio-tarsal and calcaneo-astragaloid joints. This muscle is of
great importance in walking, as it lifts up the anterior part of the foot and so
enables the toes to clear the ground when the leg is swinging forwards to begin
another step.

-
Relations. Superficially, the deep fascia; on the outer side, the extensor longus
digitorum and extensor proprius hallucis with the anterior tibial vessels and nerve;
deeply, the interosseous membrane and tibia, and in the upper part of the leg the
anterior tibial vessels. The tendon lies in a special synovial sheath beneath the
two portions of the anterior annular ligament, and upon the ankle joint and inner
bones of the tarsus. A small bursa separates the tendon from the upper part of
the inner surface of the internal cuneiform bone.
Variations. A small tendon is sometimes sent to the head of the first metatarsal bone,
the base of the first phalanx of the great toe, or to the fascia covering the instep.
2. EXTENSOR PROPRIUS HALLUCIS
The extensor proprius hallucis-named from its being the special extensor
belonging to the great toe (proprius peculiar to) is a somewhat triangular
sheet.
=
EXTENSOR PROPRIUS HALLUCIS
411
Origin. (1) The middle two fourths of the anterior (or extensor) surface of the
fibula external to the attachment of the interosseous membrane (2) the adjacent
portion of the anterior surface of the interosseous membrane.
Insertion.-(1) The ligamentous structures at the back and sides of the first
FIG. 297.-THE MUSCLES OF THE FRONT OF THE LEG.

Ligamentum patellæ
Gastrocnemius
Peroneus longus
Soleus
Extensor proprius hallucis
Dorsal interossei
Tibialis anticus
Peroneus tertius
Extensor longus digitorum
Peroneus tertius
Extensor brevis digitorum
412
21003 THE MUSCLES
metatarso-phalangeal joint; (2) the dorsal aspect of the base of the second
phalanx of the great toe.
Structure.-Arising by fleshy fibres from the bone and interosseous membrane,
the muscle is inserted in a penniform manner into a tendon which appears about
the middle of the leg upon its inner and front aspect, and becomes clear of muscular
fibres about the level of the ankle joint. The tendon now passes beneath the
upper part of the anterior annular ligament, and is then included in a special
sheath beneath the lower part of the same ligament. Opposite the first metatarso-
phalangeal joint it gives off from its sides and under surface bands of connective
tissue which unite partly with the two lateral ligaments, especially the internal one,
and partly with the periosteum upon the sides of the first phalanx. The rest of
the tendon is flattened out and fits closely to the dorsal aspect of the first phalanx;
it is finally attached to the second phalanx in a transverse line which crosses the
upper surface of its base.
Nerve-supply. From the anterior tibial by filaments which enter the inner
and deeper aspect of the muscle about the middle of the leg.
Action. (1) To extend the first phalanx of the great toe; (2) slightly to extend
the second phalanx, but this movement is chiefly performed by the small muscles
of the sole of the foot, which give off expansions to be attached to the borders of
the tendon at the sides of the first phalanx; (3) to flex the ankle, and at the
same time it will slightly adduct the front of the foot and invert the sole. When
the muscle contracts strongly it will hyper-extend the first phalanx, and at the
same time flexion of the second phalanx will be produced by the resistance of the
flexor longus hallucis tendon.
Relations in the leg.-Superficially, the deep fascia, the tibialis anticus, and the
extensor longus digitorum; internally, the tibialis anticus; externally, the extensor
longus digitorum; deeply, the interosseous membrane, the tibia, and the anterior
tibial vessels and nerve. The tendon lies beneath the two portions of the anterior
annular ligament, and after crossing the anterior tibial artery near the ankle-joint
it runs to its insertion with the dorsalis pedis and the innermost tendon of the
extensor brevis digitorum on its outer side.
Variations. The muscle is occasionally divided, and a smaller external portion joins
the first tendon of the extensor brevis digitorum, or is inserted separately into the head of
the first metatarsal bone or the base of the first phalanx.

3. EXTENSOR LONGUS DIGITORUM
upon the
The extensor longus digitorum-named from its length and its action
toes-is fusiform and somewhat flattened, with a four-divided tendon.
Origin. (1) The outer part of the under surface of the external tuberosity of
the tibia; (2) the upper three-fourths of the anterior or extensor surface of the
fibula; (3) the outer border of the anterior surface of the interosseous membrane
in its upper third; (4) the posterior surface of the deep fascia of the leg; (5) the
intermuscular septa which separate it from the upper part of the tibialis anticus
and from the long and short peronei.
Insertion. The three phalanges and the metatarso-phalangeal joints of each
of the four outer toes.
Structure. This is a penniform muscle, and its fibres arise fleshy from the
bones and the fasciæ, and pass forwards and inwards to the back and outer side
of the long tendon of insertion. This begins about the middle of the leg, and
becomes free from fleshy fibres about the level of the ankle joint; it passes behind
the upper part of the anterior annular ligament, but not in a special synovial sheath;
then beneath the lower part of the anterior annular ligament in a special synovial

EXTENSOR LONGUS DIGITORUM-PERONEUS TERTIUS 413
sheath with the peroneus tertius. At this point it divides into four tendons, which
diverge upon the back of the foot to the bases of the four outer toes. Each tendon
first gives off some strong fibres, which blend with the lateral ligaments of the
metatarso-phalangeal articulation, and with the periosteum along the borders of
the first phalanx. It then forms a broad expansion covering the back of the first
phalanx, and divides into three parts: the central part is inserted into the dorsal
aspect of the base of the second phalanx; and the two lateral parts pass forwards
with a slight convergence upon the back of the second phalanx to be inserted into
the dorsal aspect of the base of the third phalanx.
Nerve-supply. From the anterior tibial by filaments which enter the deep
aspect of the muscle in its upper third.
Action. (1) To extend the first phalanges of the four outer toes. It has some
influence upon the second and third phalanges, but the distal part of its tendon
is acted upon chiefly by the short muscles in the sole of the foot, which are
attached to the border of the expansion upon the first phalanx. When the muscle
contracts to its fullest amount the first phalanges are extended, while the second
and third phalanges are somewhat flexed by the long and short flexors. (2) To
flex the ankle joint. (3) Slightly to abduct and evert the front part of the
foot.
Relations. Superficially, the deep fascia of the leg and the anterior annular
ligaments; on its inner side, the tibialis anticus and extensor proprius hallucis, the
anterior tibial vessels and nerve with their continuations in the foot. Externally,
the intermuscular septum which separates it from the peroneus longus and brevis,
the musculo-cutaneous nerve, and, lower down, the peroneus tertius. Behind, the
fibula and interosseous membrane with the anterior tibial nerve above; below,
the ankle-joint, tarsal and metatarsal bones, and the extensor brevis digitorum.
Variations. The muscle may be divided nearly up to its origin. It may give off slips
to the extensor proprius hallucis, extensor brevis digitorum, or one of the interossei.
Sometimes also it has an insertion into some of the metatarsal bones.
4. PERONEUS TERTIUS

The peroneus tertius-named from Tepóvn, the fibula, and called tertius because
it is the third of the muscles which pass from the fibula to the metatarsus-is a
small triangular sheet which is closely blended with the preceding muscle.
-
Origin. (1) The lower fourth of the anterior (or extensor) surface of the fibula;
(2) the front of the interosseous membrane for an inch or two above the ankle
joint; (3) the external intermuscular septum and the deep fascia of the leg.
Insertion. The upper part of the base of the fifth metatarsal bone.
Structure.-Arising fleshy, the muscular fibres pass downwards and inwards in
penniform fashion to a tendon which appears on the inner border of its anterior
surface. It becomes free from fleshy fibres at the level of the ankle joint, and after
passing beneath the upper part of the anterior annular ligament, is included with
the extensor longus digitorum in a special synovial sheath beneath the lower part
of the ligament, and finally diverges from it to be inserted into the inner part of the
upper surface of the base of the fifth metatarsal bone.
Nerve-supply.-Unlike the other peronei, which are supplied by the musculo-
cutaneous nerve, it receives filaments from the anterior tibial which enter the inner
and deep aspect of the muscle in the upper part of its course.
Action.-(1) To flex the ankle joint; (2) to abduct the anterior part of the foot;
(3) slightly to elevate the outer border of the foot and so to produce eversion of the
sole.
Relations. Superficially, the anterior annular ligament and branches of the
414
THE MUSCLES
musculo-cutaneous nerve; on the inner side, the extensor longus digitorum, of which
it is really a subdivision; on the outer side, the peroneus brevis; deeply, the ankle
and outer tarsal joints with the extensor brevis digitorum.
FIG. 298.-THE MUSCLES OF THE DORSUM OF THE FOOT.

Extensor longus
digitorum
Tibialis anticus
Extensor brevis
digitorum
Peroneus brevis
Extensor proprius
hallucis
Peroneus tertius
Dorsal interossei-
Flexor brevis minimi
digiti
Variations. The peroneus tertius is often closely blended with the extensor longus
digitorum. It is sometimes wanting, and replaced by a slip of tendon from the extensor
longus digitorum. Occasionally it sends slips of tendon to the expansion of the extensor
longus digitorum on the first phalanx of the two outer toes, or to the fourth dorsal
interosseous.
EXTENSOR BREVIS DIGITORUM-PERONEUS LONGUS 415
MUSCLE ON THE DORSUM OF THE FOOT
This consists of the four bellies of one muscle-the extensor brevis digitorum.
EXTENSOR BREVIS DIGITORUM
The extensor brevis digitorum-named from its being the shorter of the two
muscles which extend the toes-is a triangular sheet which breaks up in front into
four small divisions.
-
Origin. (1) The outer part of the upper surface of the great process of the
calcaneum; (2) the interior of the loop of fascia which forms the outer part of the
lower anterior annular ligament.
Insertion. By four tendons into the four inner toes; the innermost is attached
to the outer border of the upper surface of the first phalanx of the great toe near
its base; the three other tendons to the outer border of the tendons of the extensor
longus digitorum just in front of the bases of the first phalanges.
Structure.-Arising superficially by fleshy, and on the deep surface by short
tendinous fibres, the muscle diverges inwards and forwards, and soon divides into
four fleshy bellies, of which that to the great toe is the largest and most separate.
Each portion has a bipenniform arrangement, with its central tendon upon the
dorsal surface, and becoming free opposite the middle of the metatarsus.
Nerve-supply. From the anterior tibial nerve by small filaments which enter
the deep surface of the muscle near its inner border as it crosses the cuboid and
external cuneiform bones.
Action.-(1) To extend the four inner toes. In the case of the outer toes the two
last phalanges will be chiefly extended, and the obliquity of its insertion, by causing
it to draw the toes somewhat outwards at the same time that it extends them, will
enable it to correct the opposite tendency of the long extensor. (2) The innermost
tendon will act as an adductor of the first phalanx of the great toe.
Relations. Superficially, the tendons of the extensor longus digitorum and
peroneus tertius; deeply, the tarsal and tarso-metatarsal joints; and, in the case of
the tendon to the great toe, the dorsalis pedis vessels and the termination of the
anterior tibial nerve.
Variations. The number of tendons may be diminished or increased. Sometimes a
tendon is given to the little toe. Accessory bundles may be derived from some of the
tarsal or metatarsal bones, and slips have been found running to the dorsal interossei;
and also a small slip between the first and second bellies, going to the inner side of the
second toe or its metatarsal bone.

MUSCLES ON THE OUTER SIDE OF THE LEG
Consists of two muscles-the peroneus longus and brevis-situated upon the
outer side of the fibula in a compartment of quadrilateral section, bounded inter-
nally by the fibula, in front and behind by intermuscular septa, and externally by
the deep fascia of the leg.
1. PERONEUS LONGUS
The peroneus longus (figs. 292, 296)-named from its being the longer of the
two fibular muscles-is long and fusiform.
416
THE MUSCLES TOP
Origin. (1) The outer tuberosity of the tibia by a few fibres; (2) the front of
the head of the fibula; (3) the upper two-thirds of the outer (or peroneal) surface
of the fibula, occupying the whole of this surface above, and the posterior half of it
below; (4) the inner surface of the deep fascia of the leg, and the opposed surfaces
of the two external intermuscular septa.
Insertion. (1) The lower part of the outer surface of the base of the first meta-
tarsal bone; (2) the lower part of the outer surface of the internal cuneiform bone
close to its articulation with the first metatarsal bone.
Structure. This is a strong penniform muscle, the short fleshy fibres of which
pass downwards, and for the most part forwards, to be inserted into the tendon
which, beginning about three inches below the head of the fibula, runs along the
front of the outer surface of the muscle, and becomes free in the lower third of the
leg. It then passes behind the outer ankle, beneath the external annular ligament,
in a special sheath with the tendon of the peroneus brevis, which lies in front of it.
On the outer surface of the calcaneum it runs forwards and downwards in a special
compartment of the external annular ligament below the companion tendon. At
the outer border of the foot it again changes its direction, and passes obliquely
inwards and forwards across the sole of the foot, in a canal formed by the long
plantar ligament beneath, and by the groove in the cuboid bone above, to its
insertion near the inner side of the sole. In the upper two-thirds of the leg the
peroneus longus almost entirely conceals from view the peroneus brevis, which lies
beneath and slightly anterior to it.
The synovial tube which it enters at the outer ankle is common to it and the
peroneus brevis, and bifurcates to accompany the two tendons where they are
separated by the peroneal tubercle of the os calcis. A second sheath envelopes the
tendon in the sole, and where the tendon enters this canal it often contains a
sesamoid bone which plays upon the front of the ridge of the cuboid bone.
Nerve-supply. From the musculo-cutaneous branch of the external popliteal
nerve by filaments which enter the deep and posterior aspect of the muscle in its
upper third.
Action.-(1) To extend the ankle joint; (2) to abduct the anterior part of the
foot; (3) to depress the inner border of the foot, and so to evert the sole; (4) by
drawing backwards and outwards the base of the first metatarsal bone, it tends to
render more concave the antero-posterior and transverse arches of the foot. In the
former action it assists the tibialis posticus.
In walking, it will act with the gastrocnemius and soleus in lifting the heel from
the ground, and its tendency to evert the sole and abduct the foot will counteract
the opposite tendency of the muscles attached to the tendo Achillis. Moreover, the
tendency of this latter set of muscles is to press the outer part of the ball of the
toes firmly upon the ground. On the other hand, the influence of the peroneus
longus in extending the foot is especially exerted upon the ball of the great toe.
By the combined action of all these extensors of the ankle the whole of the ball
of the foot is pressed evenly upon the ground and firmness of tread secured.
Relations. Superficially, the deep fascia, the external annular ligament; and in
the sole the abductor minimi digiti, the adductor hallucis, and long plantar ligament;
in front, the peroneus brevis, the extensor longus digitorum, and the musculo-
cutaneous nerve; behind, the soleus and flexor longus hallucis; deeply, the external
popliteal nerve which occupies a fibrous canal below the head of the fibula, the
ankle joint, calcaneum, cuboid, and the bases of the second and third metatarsal
bones.
Variations. Sometimes a second peroneus arises between the peroneus longus and
brevis, and sends its tendon to join that of the peroneus longus. A slip may be given to
the external annular ligament. The insertion of the muscle may extend to the bases of
the adjacent metatarsal bones.
PERONEUS BREVIS-EXTERNAL INTERCOSTALS
417
2. PERONEUS BREVIS
The peroneus brevis (figs. 292, 298)-named from its being the shorter of the two
fibular muscles-is also a triangular sheet.
-
Origin. (1) The lower two-thirds of the outer (or peroneal) surface of the
fibula; (2) the deep fascia of the leg and the intermuscular septa in front and behind.
Insertion.-(1) The outer part of the base of the fifth metatarsal bone; (2) the
outer border of the expansion of the tendon of the extensor longus digitorum upon
the first phalanx of the little toe.
Structure-This is also a penniform muscle. The short fibres pass obliquely
forwards and inwards to the tendon which runs along the outer surface of the
muscle close to its anterior border. It becomes free from fleshy fibres just above
the external malleolus where it passes beneath the external annular ligament in the
same sheath with the peroneus longus tendon, and after changing its direction runs
forwards and somewhat downwards upon the outer surface of the calcaneum and
above the peroneal tubercle.
Nerve-supply. The musculo-cutaneous branch of the popliteal nerve by
filaments which enter the deep aspect of the muscle about the middle of the leg.
Action.-(1) Slightly to extend the ankle; (2) to abduct the anterior part of
the foot; (3) slightly to elevate the outer border of the foot and so evert the sole.
Relations. Superficially, the peroneus longus, deep fascia of the leg and external
annular ligament; in front, the extensor longus digitorum and peroneus tertius;
behind, the peroneus longus and flexor longus hallucis; deeply, the ankle joint,
calcaneum, and cuboid bones.
Variations. The small slip which the tendon sends on to the expansion upon the little
toe may be wanting, or it may be inserted into the first or even the second phalanx. This
slip may be entirely separate, so as to form a fourth peroneus.

THE MUSCLES OF THE THORAX
These consist of six muscles, or sets of muscles, which are attached chiefly to the
ribs, their cartilages, and the sternum: viz. the external and internal intercostals,
the levatores costarum, the triangularis sterni, infracostales (or subcostales), and
diaphragm.
INTERCOSTAL MUSCLES
The intercostal muscles-named from their position-are long narrow sheets of
short oblique muscular fibres which occupy the intercostal spaces. The fibres of
the outer sheet run downwards and forwards, and those of the inner downwards
and backwards; and the two sheets are the upper continuations of the obliquus
externus and internus of the abdominal wall.
1. THE EXTERNAL INTERCOSTALS
The external intercostals, which are stronger than the internal, are eleven in
number, and fill the space between the ribs from the tubercle to the tip. In the
higher spaces, however, they do not come quite so far forwards as below. Above,
EE
418
THE MUSCLES
the lower attachment barely reaches the tip of the rib; while below, the upper
attachment reaches the tip, and the lower is upon the cartilage.
Origin. The lower or outer border of all the ribs except the last, from tubercle
to anterior extremity.
FIG. 299.-THE EXTERNAL INTERCOSTALS AND LEVATORES COSTARUM.

Complexus
Obliquus superior.
Rectus capitis posticus major-
Obliquus inferior
Rectus capitis posticus minor
Multifidus spinæ
Semispinalis colli.
Cervicalis ascendens-
Longissimus dorsi-
SEVENTH CERVICAL VERTEBRA
Semispinalis dorsi
Multifidus spinæ
Levator costæ-
Longissimus dorsi
Ilio-costalis-
-TWELFTH THORACIC VERTEBRA
Multifidus spinæ
Obliquus internus-
Lumbar fascia.
Ilio-costalis-
FIFTH LUMBAR VERTEBRA
Multifidus spinæ
EXTERNAL AND INTERNAL INTERCOSTALS
419
Insertion. The outer aspect of the upper border of all the ribs but the first
from a little in front of the tubercle to the tip, or in the lower ribs for a short
distance upon the cartilage.
Structure.-Composed of obliquely directed parallel bundles of fleshy fibre, with
a short tendinous origin, and with a slight admixture of fibrous tissue. The
posterior are more oblique than the anterior fibres. The sheet formed by these
fibres is thickest behind, and becomes gradually thinner forwards. Between the
cartilages it is succeeded by a thin membrane, the external intercostal fascia, which
is composed of fibres running with the same slope as those of the muscle.
Nerve-supply. The intercostal nerves as they run forwards give numerous
filaments to the inner surface of the sheets.
Action.-See later.
Relations. Superficially, the pectoralis major and minor, the serratus magnus,
the external oblique, the latissimus dorsi, the trapezius, rhomboidei, the serrati
postici, the continuation upwards of the erector spinæ, and the levatores costarum ;
deeply, the internal intercostals and infracostales, the intercostal vessels and nerves.
2. THE INTERNAL INTERCOSTALS

The internal intercostals are eleven in number, and fill the space from the
angles of the ribs to the anterior extremity of the cartilages. The fibres, which are
shorter and not quite so oblique as those of the outer sheet, are directed downwards
and backwards.
Origin. The upper border of the subcostal groove of the eleven upper ribs from
the angle forwards, and the continuation of this border upon the cartilages.
Insertion. The inner aspect of the upper border of the eleven lower ribs and
cartilages.
Structure. The sheets are thicker in front. There is less fibrous tissue mixed
with the fleshy fibres than in the outer sheet. In the upper and lower spaces the
fleshy fibres are continued a little further back than the angles. The rest of the
space behind the thin posterior border of the sheet is filled by a thin membrane
composed of fibres running in the same direction, and is called the internal
intercostal fascia.
Nerve-supply.-Branches from the intercostal nerves, which are supplied to its
outer surface or are given off where the nerves are concealed in the interior of the
muscle.
Action.-See below.
Relations. Superficially, the external intercostal muscles, and the intercostal
arteries and nerves; deeply, the triangularis sterni, infracostales, and the pleura.
The action of the intercostal muscles generally is to approximate the ribs to each
other, and they are chiefly used in inspiration. The obliquity of their fibres enables
them with a small contraction to produce a greater approximation than if they
ran perpendicularly between the ribs (page 301). Moreover, if the fibres were all
directed, like those of the outer sheet, downwards and forwards, there would be a
tendency for the lower ribs to be drawn backwards as well as upwards in inspiration;
and if, on the other hand all the fibres were directed downwards and backwards like
those of the inner sheet, the tendency would be for the lower ribs to be drawn
forwards as well as upwards in inspiration. The combined action of the two sets
produces the direct elevation of the ribs, the forward pull of the inner sheet being
counteracted by the backward pull of the outer sheet. If the external intercostals
were carried forwards as far as the sternum, they would tend to take the sternum
as a fixed point and to depress the front extremities of the ribs. A similar result
would follow the continuation backwards of the internal intercostals to the vertebral
EE 2
420
THE MUSCLES
column. It will be also noticed that the front part of the external, and the back part
of the internal intercostal sheets are thin and weak, so as to diminish this tendency
towards an expiratory movement. It has been urged that both sets of intercostals
cannot approximate the ribs, as in inspiration some of the intercostal spaces are seen
to open out and become wider. To this it may be replied that, whatever happens in
some of the spaces, it is certain that the general tendency is that of approximation
of the ribs and diminution of the intervals between them, as after a full inspiration
the last rib is nearer to the first rib. Moreover, it does not always follow that because
a muscle is lengthening it may not be acting (cf. such cases as that of the long
head of the triceps when it is used in extending the elbow during the elevation of
FIG. 300.-THE INTERCOSTAL MUSCLES.

External-
intercostals
ரதிசம்
External
intercostals
Internal-
intercostals
-Internal
intercostals
-Infra-costales
the arm). If when most of the ribs are being approximated it should happen that
some of the spaces are found to be widened, the action of the muscle in these
widened spaces will probably be to prevent a greater separation, and by steadying the
lower ribs to enable the muscles which descend from them to act. When the
lowest rib is fixed by the quadratus lumborum and other muscles, it is probable that
the intercostals, at any rate those of the lower spaces, by approximating the lower
ribs to the last rib, may act as muscles of expiration. The following are some
of the arguments which may be adduced in support of the view that both sets of
intercostals act together, and also that their action is usually inspiratory.
1. The advantage already mentioned, from their oblique decussation enabling
them to approximate the ribs more completely and at the same time to elevate them
LEVATORES COSTARUM-TRIANGULARIS STERNI
421
directly when they act in combination (cf. the action of the external and internal
oblique in approximating the last rib to the crest of the ilium).
2. Muscles supplied by the same nerve are rarely antagonistic.
3. In long-standing paralysis of the intercostals the sternum is depressed, the
chest flattened, and kept in a permanent condition of exaggerated expiration.
4. Galvanism of the intercostals produces expansion of the chest. In Duchenne's
experiment he found that when he galvanised so slightly as only to affect the
external intercostals, the inspiratory movement was small; but when he galvanised
so strongly as to affect the nerve, and through the nerve the internal intercostals-
as was known by the contraction of muscular fibre being felt between the cartilages
of the ribs, in which situation the only fleshy fibres are those of the inner set-a
strong inspiratory movement was produced.
From the peculiar shape of the ribs and the mode of their articulation, their
elevation is accompanied by a rotation of the arcs formed by them upon their chords
so that their planes from a sloping attain an almost horizontal position. Hence the
widening of the chest during inspiration, in addition to the increase of movement
from before backwards due to the elevation of the tips of the ribs.

3. LEVATORES COSTARUM

The levatores costarum (fig. 299)-named from their action, as elevators of the
ribs-are twelve triangular sheets, which cover the back part of the intercostal
spaces, and are continuous with the fibres of the external intercostal muscles.
Origin. The tips of the transverse processes of the the last cervical, and all
the thoracic vertebræ except the last.
Insertion. The outer surface of the ribs from the tubercle to the angle.
Structure.-Arising by short tendinous fibres, the muscle expands in a fan
shape, and is attached to the next rib below. Frequently fibres pass over one rib
and are inserted upon the next but one.
Nerve-supply. The intercostal nerves which send branches to their deep
surfaces.
Action.-To elevate the ribs in inspiration.
Relations. Superficially, the outer upward continuations of the erector spinæ ;
deeply, the external intercostals, which are continuous with the outer border of
the muscles.
4. TRIANGULARIS STERNI
As the external and internal oblique muscles of the abdomen are represented
by the external and internal intercostals in the thorax, so also the transversalis
abdominis has its counterpart in the thin stratum of muscular fibre at the sides of
the sternum called the triangularis sterni, and the still thinner expansion behind of
the infracostales.
The triangularis sterni-named from its shape and its connection with the
sternum-is a thin, musculo-membranous, triangular sheet, with the apex below
and directed internally, while the serrated base is external.
--
Origin. (1) The side of the lower third of the back of the sternum; (2) the
upper and lateral part of the back of the ensiform cartilage; (3) the back of the
inner ends of the fifth, sixth, and seventh costal cartilages.
Insertion. The outer end of the back and lower border of the cartilages of the
second or third to the sixth ribs, and occasionally the tip of the ribs also.
Structure. The muscle is membranous at its origin and insertion, and it contains
many bands of fibrous tissue. Its fibres diverge fanwise, the lower ones being
422
PHONY'S THE MUSCLES
horizontal, and in serial continuation with the upper digitations of the transversus
abdominis, while its higher fibres run obliquely upwards and outwards.
Nerve-supply. The upper intercostals, which send filaments to its anterior
aspect.
Action. To depress the anterior extremities of the ribs to which it is attached,
and so to help in expiration.
Relations. In front, the internal intercostals, cartilages of the ribs, and internal
mammary vessels; behind, the pleura and pericardium.
FIG. 301.-THE MUSCLES ATTACHED TO THE BACK OF THE STERNUM.

Sterno-thyroid-
Triangularis
sterni
Sternal
origin of
diaphragm
Costal
origin of
diaphragm
Transversalis abdominis
Sterno-hyoid
Triangularis
sterni
5. INFRACOSTALES
The infracostales or subcostales-named from their position beneath the ribs-
form a thin musculo-membranous sheet lining the back of the thorax external to
the tubercles of the ribs; broader and better developed below, becoming narrower
and thinner above. Frequently it consists of only a few bundles of fibres which
can be distinguished from the internal intercostals by the fact that they are not
confined to one intercostal space.
Origin. The lower part of the inner surface of the ribs near their angles.
Insertion. The upper part of the inner surface of the ribs, each bundle of
fibres usually passing over one rib to be inserted upon the next higher.
Structure. The fibres arise tendinous, run upwards and outwards, and have
tendinous insertions. The higher fibres run more vertically. The lower approach
nearer to the vertebral column, arising from the ribs just external to their tubercles.

INFRACOSTALES DIAPHRAGM
423
Nerve-supply. The intercostal nerves, which enter their outer surface.
Action.-To depress the ribs, and assist in expiration.
Relations.-Externally, the external and internal intercostal muscles; internally,
the parietal layer of the pleura, which is separated from them by a thin aponeurosis
sometimes called the endothoracic fascia.
6. THE DIAPHRAGM

The diaphragm-named from its function as the diappayua, or partition wall
between the thorax and abdomen-is a dome-shaped musculo-membranous sheet of
a kidney-shaped outline when seen from above, and consists of a pair of muscles
with a lateral origin and a central aponeurotic insertion, resembling the two
transversales abdominis, which unite in the linea alba so as also to form a single
dome-shaped biventral muscle.
FIG. 302.-DIAPHRAGM.

Opening for
vena cava
inferior
Right division
of tendon
Aorta
Right crus
Psoas parvus
Psoas
Transversalis
abdominis
Quadratus
lumborum
Sternal origin
-Middle division
of tendon
Esophagus
Left division of
tendon
-Costal origin
Ligamentum
arcuatum
internum
Left crus
Ligamentum
arcuatum
externum
Transverse
process of
second lumbar
vertebra
Fourth lumbar
vertebra

Origin. By three portions:--
1. Anterior or sternal portion.-The lower border and back of the ensiform
cartilage, and the adjacent part of the back of the anterior aponeurosis of the
transversalis abdominis.
2. Lateral or costal portion.-The lower border and inner surface of the
cartilages of the six lower ribs, and sometimes also from the adjacent part of
the ribs.
3. Posterior or vertebral portion.-(1) The ligamentum arcuatum externum, a
fibrous thickening of the anterior layer of the lumbar fascia, which stretches from
the tip of the transverse process of the second lumbar vertebra to the tip of the
last rib; (2) the ligamentum arcuatum internum-a fibrous thickening of the
iliac fascia, which arches over the upper part of the psoas from the side of the body
of the second lumbar vertebra to the tip of its transverse process; (3) the crus of
the diaphragm-a strong vertical band, fleshy externally, tendinous internally-
424
THE MUSCLES
arising on the right side from the front of the bodies of the first to the third or
fourth lumbar vertebræ, from the intervening vertebral discs, and the anterior
common ligament; on the left side, from the bodies of the first to the second or
third vertebræ only, as well as the discs and anterior common ligament.
Insertion. The front, sides, and back, of the central tendon.
Structure. The fibres, arising fleshy from their extensive origin, pass at first
vertically upwards, and then arch inwards to be attached to the borders of the
central tendon. The sternal fibres are the shortest, and they are often separated
from the costal portion by a small triangular interval filled with areolar tissue, and
giving passage to the superior epigastric vessels. The costal origin forms a series
of teeth which do not correspond accurately with the number of ribs, some rib
cartilages having two teeth attached to them. They interdigitate with the serrations
of the transversalis abdominis (fig. 301). The aponeurotic fibres which form the
inner portion of the two crura, after arching in front of the abdominal aorta, are
continued by fleshy fibres which decussate, and so changing sides form a loop round
the œsophagus before joining the central aponeurosis.
The central tendon, or aponeurosis, forms the summit of the dome, and is of a
similar outline to the diaphragm, being kidney-shaped, with the concavity behind.
It approaches nearer the back than the front of the thorax. There is a slight
notching of its outline in front, which divides it into three parts, so that it has
somewhat of a trefoil shape, the right leaflet being the largest, and the left the
smallest. Its fibres run in many directions.
The diaphragm contains three large foramina, for the passage of the vena cava
inferior, œsophagus, and aorta.
Foramina.-Close to the posterior border of the central tendon at the junction
of the right and middle leaflet is a quadrilateral opening with rounded angles, the
foramen for the vena cava inferior, the outer coat of which vessel is blended with its
fibrous edges. The œsophageal opening is oval, with the long diameter directed
forwards. It is surrounded by fleshy fibres, and lies to the left of the middle line,
opposite the body of the tenth thoracic vertebra. Through it passes the œsophagus,
with the left vagus nerve in front, and the right behind; also a few small œsophageal
branches from the thoracic aorta, on their way to join some small œsophageal
branches from the gastric artery. The aortic opening, formed by the union of the
crura, is fibrous, and of oval shape. It is situated in front of the twelfth thoracic
vertebra, and is completed behind by the anterior common ligament. Through it
pass the aorta, the vena azygos major, and the thoracic duct. In the crura on
either side are small openings which allow of the passage of the great splanchnic
nerves, and the left crus is usually perforated also by the vena azygos minor.
Nerve-supply. The two phrenic nerves, chiefly derived from the cervical plexus
of each side through the fourth cervical nerves, break up close to the diaphragm
into many filaments, which penetrate the muscular structure near the anterior
border of the central tendon, and are distributed to the under surface of the
muscle. Sympathetic filaments are also given to it from the plexuses which
accompany the phrenic arteries.
Action. To deepen the chest from above downwards, and so produce a move-
ment of inspiration. The central tendon, which is closely connected by means of
the pericardium with the deep fascia of the neck, is but little depressed; but the
arched fleshy fibres all around flatten, and so increase greatly the capacity of the
sides of the thoracic cavity. At the same time the abdominal viscera are driven
downwards, and as the front part of the parietes is the most yielding, they are also
displaced forwards, so as to cause a greater prominence of this part of the abdomen.
In the expulsive efforts of defecation and parturition, after the diaphragm has first
contracted in a deep inspiration, and the glottis has been closed so as to prevent
the escape of air from the chest, the abdominal muscles are able to contract with


ABDOMINAL PARIETES AND MUSCLES
425
full effect upon the viscera, which have been pressed down by the previous descent
of the diaphragm.
The lower six ribs are slightly elevated by the diaphragm, and the hypochondria
somewhat dilated, this latter movement being due to the forward and outward
pressure of the depressed viscera.
Relations. Above lie the pleuræ and pericardium, the heart and the lungs.
Below are the peritoneum, the liver with its ligaments, the stomach, the spleen,
pancreas, kidneys, and suprarenal capsules. The dome-shaped upper convex surface
rises higher upon the right than the left side. On the right side, being raised by
the liver, it reaches to the level of the junction of the fifth costal cartilage with the
sternum, and on the left side only to the level of the junction of the sixth costal
cartilage.
Variations. The oesophageal opening has been found in the right crus, instead of being
surrounded by decussating fibres from both crura. The sternal portion of the muscle is
not infrequently absent.

THE ABDOMINAL PARIETES
The superficial fascia covering the walls of the abdomen is continuous with that
of the thorax and lower limbs, and is usually divided into two layers.
The first layer is well provided with fat, which in many individuals attains to a
considerable thickness, especially in the lower part of the anterior wall.
The second or deep layer (Scarpa's fascia) is of a more membranous character
and contains a quantity of elastic fibres. Near the groin it is separated from the
more superficial layer by blood-vessels and lymphatic glands. Upon its deeper
surface it is loosely connected with the deep fascia which invests the external
oblique muscle; but it is closely blended with the linea alba, the fibrous structures
in front of the pubic bones, the fascia lata immediately below Poupart's ligament,
and the crest of the ilium.
Both layers are continued downwards upon the external genital organs. In
the male they lose their fat and blend with the suspensory ligament of the penis,
the fascia covering that organ, and the dartos and septum of the scrotum. In the
female they are continuous with the superficial fascia of the vulva.

THE ABDOMINAL MUSCLES
The muscular portion of the abdominal wall forms a lozenge-shaped figure of
which the vertical diagonal extends from the ensiform process to the symphysis
pubis, while the transverse encircles the abdomen from tip to tip of the transverse
processes of the third lumbar vertebra.
The boundaries of this muscular wall are formed, above by the costal cartilages
of the six lower ribs; behind, by the tips of the transverse processes of the lumbar
vertebræ; below, by the crests of the ilia and the pubes. More accurately, each
lateral half may be looked upon as a four-sided figure of which the upper boundary
slopes backwards and downwards; the lower, backwards and upwards; while the
long anterior boundary and short posterior boundary are vertical and parallel. The
426
THE MUSCLES
muscles contained in the parietes may be divided into vertical and transverse.
The former, three in number, are situated two in front, and one behind; while the
latter, also three in number, pass transversely, or with some obliquity, between the
anterior and posterior boundaries of the space.
The two lateral halves unite in front in a strong fibrous band called the linea
alba, which stretches from the tip of the ensiform cartilage to the upper part of the
symphysis pubis. It is partly formed by vertical fibres stretching between these
two points, but chiefly by the interlacement of the transverse and oblique bands
of fibrous tissue which pass between the aponeuroses of the muscles upon either
side. In its lower two-fifths it is not more than one-eighth of an inch broad;
in its upper three-fifths it is broader, usually not less than a quarter of an inch
in width, but in some bodies it may be stretched to a much greater extent. At
the junction of the lower two-fifths and upper three-fifths is the small fibrous ring
of the umbilicus through which pass the remnants of the foetal vessels.
ANTERIOR VERTICAL MUSCLES
These are two in number-the pyramidalis and rectus abdominis.
1. PYRAMIDALIS
The pyramidalis (fig. 266)-named somewhat fancifully from its triangular
shape is a fan-shaped sheet of muscular fibre forming a right-angled triangle,
of which the shortest side corresponds to the origin, and the other side containing
the right angle to the linea alba.
Origin. (1) The front of the pubic crest; and (2) the fibrous structures
which cover the front of the body of the os pubis and its symphysis.
Insertion. The linea alba at a point about half-way between the pubes and
the umbilicus.
Structure.-Arising by a short tendinous sheet, the fleshy fibres converge as they
pass upwards. Those nearer to the middle line ascend vertically, while those which
arise near the pubic spine pass obliquely upwards and inwards to the tendinous
insertion of the muscle into the linea alba three or four inches above the
symphysis pubis.
Nerve-supply. From the eleventh and twelfth thoracic nerves and from the
ilio-hypogastric branch of the lumbar plexus, through their terminal filaments
which enter the deep surface of the muscle.
Action. By its contraction it pulls upon the linea alba and so upon the lower
end of the ensiform cartilage. It will therefore assist the rectus in flexion of the
thorax upon the pelvis, or of the pelvis upon the thorax. It can also help feebly to
compress the abdominal viscera.
Relations. Superficially, the aponeuroses of the transverse abdominal muscles;
deeply, the rectus abdominis, from which it is separated by a thin fibrous lamella.
Variations. The height to which this muscle extends is variable. It may be absent
on one or both sides; or it may be double.
2. RECTUS ABDOMINIS
The rectus abdominis (fig. 266)-named from its straight direction-is a strong
ribbon-shaped muscle running vertically on either side of the linea alba from the
pubes to the ensiform and adjacent costal cartilages.
Origin. By two tendons : (1) the larger or outer head from the whole of the
-
RECTUS ABDOMINIS
427
crest of the pubes; (2) the inner head crosses the middle line of the body, and
arises from the fibrous structures lying in front of the symphysis.
Insertion.-(1) The anterior surface of the tip of the fifth rib; (2) the front of
the costal cartilages of the fifth, sixth, and seventh ribs; sometimes also (3) the
deep posterior surface of the ensiform cartilage near its outer border.
Structure. The inner head arises tendinous from the other side of the middle
line, decussating with its fellow; the outer and stronger head arises by a shorter
tendon, and is soon joined by the inner head. About an inch above the pubes a
fleshy mass is formed, which expands as it ascends into a broad sheet, which below
the umbilicus lies close to its fellow of the opposite side. Above, the two muscles
are separated by an interval of at least a quarter of an inch. The insertion, which
is by short tendinous fibres, is three or four times the width of the origin. The
muscle is also curved considerably forwards to correspond with the convexity of the
front wall of the abdomen. At certain intervals transverse bands of fibrous tissue
extend in an irregular zigzag manner across the muscle, especially upon its anterior
surface. These are called the lineæ transverse, and the transverse depressions
which they produce are usually to be seen and felt through the skin. They are
generally three or four in number on either side. One is situated opposite the
umbilicus; the second opposite the tip of the ensiform cartilage; the third half-
way between these points; and a fourth is sometimes present which extends
incompletely across the muscle at some distance below the umbilicus. They are
firmly connected with the anterior layer of the strong sheath of the muscle, which
will afterwards be described. They do not extend through the whole thickness of
the muscle, being deficient behind.
Nerve-supply. From the terminal filaments of the anterior branches of the
six lower thoracic nerves which enter the muscle on its posterior surface near the
outer border; and from the ilio-hypogastric branch of the lumbar plexus.
Action.-(1) By the tendency of the curved bands of the muscle to become
straight during contraction, all the viscera contained in its concavity are compressed.
It will, therefore, help in defecation, micturition, and parturition; also in expira-
tion, and especially in strong expiratory efforts, such as coughing and sneezing.
(2) By drawing down the ensiform cartilage and the anterior extremities of the
middle ribs, it flexes the thorax upon the pelvis, and at the same time acts as a
flexor of the thoracic and lumbar portions of the spine. Acting less strongly, it
fixes the sternum, so that the sterno-mastoids by their contraction may flex the head,
e.g. in rising from the recumbent position. (3) Taking its fixed point from above,
it will draw upwards the pubic portion of the pelvis, and so flex the pelvis upon the
thorax, as when the lower part of the body is drawn up towards the chest in climbing.
The lineæ transverse, which are the remnants of the septa which divide the
muscular structure at intervals in the lower vertebrates, and which in the crocodile
form the abdominal ribs, have had various uses assigned to them. In the first
place, they will tend to keep the muscular fibres in their proper place, and prevent
them from being separated so as to allow of ventral hernia. Secondly, they will
enable the muscle to act not only upon the points of bone which form its direct
attachment, but, by means of their connection with the sheath of the muscle and
the aponeuroses of which it is formed, they will in some measure diffuse the action
of the muscle over the lower ribs and the crest of the ilium. Thirdly, they will
enable one part of the muscle to act independently, as for example when the lower
part exercises some pressure upon the bladder in micturition. Fourthly, they
prevent extensive separation when the muscle is injured. On account of the severe
strain to which the muscle is exposed, it is sometimes ruptured. If the muscular
fibres extended without interruption from the pubes to the ensiform cartilage,
such a rupture would occasion a much wider separation, and consequently much
greater disablement than is now found to be the case.


428
THE MUSCLES
Relations. Superficially, the front layer of its sheath above, and below the
pyramidalis; deeply, it is separated from the transversalis fascia and peritoneum in
the greater part of its course by the posterior layer of its sheath; in its lower
fourth it is in contact with the transversalis fascia; and above, it lies on the
cartilages of the fifth to the ninth ribs, and covers the intercostal muscles which
lie between them.
Variations. The rectus may be inserted as high as the fourth or even the third rib.
A lateral rectus is sometimes found between the external and internal oblique muscles,
extending from the tenth rib to the iliac crest.
TRANSVERSE AND OBLIQUE MUSCLES
This group consists of three muscles the obliquus externus, the obliquus
internus, and the transversalis-which lie in successive strata in the abdominal wall.
1. OBLIQUUS EXTERNUS
The obliquus externus abdominis-named from its position and direction-is a
broad curved sheet, partly muscle and partly aponeurosis, of an irregular quadri-
lateral shape.
Origin. The outer surface of the eight lower ribs about their middle by a series
of nearly horizontal lines which, after crossing each rib obliquely downwards and
backwards, extend for a short distance along its lower border.
Insertion. (1) By a strong aponeurosis along the whole of the linea alba;
(2) the front of the os pubis close to the symphysis; (3) the spine of the pubes
and the adjacent part of the ilio-pectineal line; (4) the deep fascia of the thigh
in a thickened band which stretches from the spine of the pubes to the anterior
superior spine of the ilium; (5) the anterior half of the outer lip of the crest
of the ilium; (6) at the lower part of the linea alba some of the fibres (the
triangular fascia) stretch across the middle line, and are inserted into the front
of the crest of the pubes and the inner part of the ilio-pectineal line of the other
side.
Structure. At their origin the muscular fibres form a series of teeth which
interdigitate in the upper part of the muscle with the serratus magnus, and in the
lower with the latissimus dorsi. The general direction of the origin is an oblique
line somewhat curved upon itself so as to be convex upwards and backwards.
Above and below, the origin is nearer to the anterior extremity of the ribs. From
this origin the fleshy fibres pass downwards and forwards, and at the same time
diverge fanwise, at first lying upon the ribs and their cartilages, and then without
any bony support as part of the muscular wall of the abdomen. The change from
fleshy to tendinous fibres takes place at some distance from the outer border of
the rectus muscle, in such a way that the fleshy mass terminates rather abruptly
in a right angle situated in the iliac region of the abdomen. This angle is
formed in front by a vertical line, which passes downwards from the tip of the
ninth costal cartilage; and below by a horizontal line passing forwards from a
point upon the crest of the ilium an inch or two behind the anterior superior spine.
This abrupt limitation of the muscular fibres gives rise to a projection which
is distinctly visible through the skin in a muscular subject. The aponeurosis thus
formed blends in nearly the whole of its extent with that of the adjacent muscle,
the obliquus internus, and in the middle line it unites at the linea alba with that of
the opposite side. Above, it extends upwards as high as the insertion of the rectus
muscle, of which it forms part of the sheath, and in this locality it gives origin to
OBLIQUUS EXTERNUS
429
a part of the pectoralis major. At the lower end of the linea alba the portion
which, crossing the middle line, is inserted into the crest of the pubes and the ilio-
pectineal line of the other side, is known by the name of the triangular fascia.
FIG. 303.-EXTERNAL OBLIQUE AND ILIO-TIBIAL BAND.

Pectoralis major
Origin of pectoralis
major from aponeurosis
of obliquus externus
Obliquus externus
Linea semilunaris
Trapezius
Serratus magnus
Latissimus dorsi
Tensor vaginæ femoris
Gluteus maximus
Tendon of biceps
Ilio-tibial band
430
THE MUSCLES
The insertion into the pubic bone of the same side is interrupted by an interval
corresponding to the crest of the pubes, and forms the external abdominal ring.
From the spine of the pubes to the anterior superior spine of the ilium, the
aponeurosis forms a thickened band slightly convex downwards, which blends with
the fascia lata, and is called Poupart's ligament. The rest of the insertion into
the outer lip of the crest of the ilium is by short tendinous fibres.
The insertion of the lower edge of the aponeurosis is also carried backwards
and outwards from the spine of the pubes along the inner part of the ilio-pectineal
line by a horizontal triangle of fascia called Gimbernat's ligament.
ligament. This
ligament is attached to the lower end of Poupart's ligament in front, and it presents
a concave surface upwards, upon which lie the structures which emerge through
the external abdominal ring.
The external abdominal ring (fig. 285) is an obliquely directed slit in the
aponeurosis of the obliquus externus, which transmits the spermatic cord in the
male, and the round ligament of the uterus in the female. The slit is formed
by the divergence of the obliquely directed fibres of the aponeurosis.
Those above, which form the inner pillar, as it is called, of the ring, run down-
wards and inwards to be attached to the front of the symphysis pubis; those
below, which form the external pillar of the ring, form a thin edge at first, but
thicken just before their attachment to the spine of the pubes and the inner
extremity of the ilio-pectineal line, for at this point the external pillar is identical
with Poupart's ligament. Upon the surface of the obliquus externus, close to the
external abdominal ring, the oblique fibres of the aponeurosis are fastened together
by some transversely directed fibres, the intercolumnar fibres, which run upwards.
and inwards from Poupart's ligament, limiting and rounding off the upper and
outer end of the external abdominal ring. A thin membrane, the intercolumnar
fascia, is prolonged from the edges of this opening over the spermatic cord and
round ligament, of which it forms the external envelope.
Nerve-supply. From the anterior branches of the lower thoracic nerves and
from the ilio-hypogastric and ilio-inguinal nerves which come from the highest
nerve of the lumbar plexus, by means of numerous filaments which, passing through
the internal oblique, enter the muscle on its deep surface.
Action.-(1) The curved muscular fibres in their contraction tend to become
straight and so compress the viscera which lie in their concavity; they act in
defecation, micturition, parturition, and all expiratory efforts; (2) the two obliqui
externi acting together will draw upwards the front part of the pelvis, and so flex it
upon the thorax; (3) the muscle of one side, acting alone or in conjunction with
the internal oblique of the opposite side, will rotate the pelvis and the lower part
of the body to the same side; (4) it will tend by its posterior fibres to draw the
crest of the ilium upwards towards the lower ribs, and will thus act as a lateral
flexor of the pelvis upon the thorax; (5) acting from below, the muscles of the
two sides will draw the thorax downwards and forwards and flex the lumbar and
lower part of the thoracic spine; (6) it will rotate the thorax upon the pelvis so as
to turn the thorax and the upper part of the body to the opposite side; (7) the
posterior fibres will flex the thorax laterally.
Relations. Superficially, the integuments, and for a short space behind the
latissimus dorsi; deeply, the lower ribs, their cartilages, the intercostal muscles
between them, and the internal oblique; and below, the spermatic cord or round
ligament in the inguinal canal.
Variations. The obliquus externus may rise from more or fewer ribs. Occasionally
a deeper plane is separated from the rest of the muscle. In one case, the anterior part of
the aponeurosis was observed to be wanting.
OBLIQUUS INTERNUS
431
2. OBLIQUUS INTERNUS
The obliquus internus abdominis (fig. 266)-named from its relation to the
preceding muscle and the direction of its fibres-is an irregular quadrilateral
curved sheet, partly fleshy and partly aponeurotic.
Origin.-(1) The outer half of Poupart's ligament; (2) the anterior two-thirds
of the space intervening between the inner and outer lips of the crest of the ilium;
(3) the outer and posterior aspect of the aponeurosis of the transversalis abdominis
(which aponeurosis is also called the lumbar fascia).
Insertion. (1) For about one inch into the inner extremity of the ilio-
pectineal line; (2) the anterior border of the crest of the pubes; (3) the whole
length of the linea alba; (4) the lower borders of the cartilages of the last three
ribs.
Structure.-Arising by fleshy and short tendinous fibres intermingled, a fleshy
sheet is soon formed, the fibres of which diverge; the anterior passing forwards
and downwards, the middle forwards and upwards, and the posterior directly
upwards to their insertion, which is by means of a broad aponeurosis. At the front
of the lower intercostal spaces the fibres run parallel to, and in the same plane
with, the internal intercostals. The position of the change from fleshy to apo-
neurotic fibres may be indicated by two lines at right angles to one another; one
passing upwards and a little outwards from the middle of Poupart's ligament, the
other horizontally forwards below the tip of the last rib, and near the edges of the
lower rib cartilages. The aponeurosis is blended with that of the external oblique,
and in its upper three-fourths it divides into an anterior and a posterior plane which
together form the sheath of the rectus muscle. In the lower fourth of the abdomen
the whole of the aponeurosis passes in front of this muscle. The line of division of
the aponeurosis of the internal oblique is indicated on the surface of the abdomen by
a furrow called the linea semilunaris, which lies between the fleshy part of the
muscle and the outer border of the rectus muscle, and forms a curve, concave
inwards, which extends from the cartilage of the eighth rib above to the vicinity of
the pubes below.
The plica semilunaris, or fold of Douglas, on the other hand, is the name
given to the lower edge of the posterior sheath of the rectus, when that muscle
pierces the aponeuroses so as to lie behind all of them in the lower fourth of its
course. The lowest portion of the aponeurosis of insertion of the obliquus internus
is closely blended with that of the transversalis abdominis, and is called the
conjoint tendon.
Nerve-supply.--From the anterior primary branches of the lower thoracic
nerves, and from the first nerve of the lumbar plexus by means of the ilio-inguinal
and ilio-hypogastric nerves. The main branches of these nerves run forwards
between this muscle and the transversalis abdominis, and give off their filaments
to the internal surface of the muscle; some also are distributed to the muscle by
the branches which perforate it in order to supply the external oblique.
Action.-(1) The fibres of the muscle being curved tend to flatten upon their
contraction and so to compress the viscera contained within their concavity;
they will therefore help in defecation, micturition, parturition, and all expiratory
efforts. (2) It will also assist expiration by drawing the lower ribs downwards. (3)
When both muscles act together, they flex the thorax upon the pelvis. They will
also flex the lumbar and lower thoracic spine. (4) When the muscle of one side
acts alone, or in conjunction with the obliquus externus of the other side, it will
rotate the thorax to its own side. (5) The posterior fibres of the muscle will draw
down the side of the thorax; it will therefore be a lateral flexor of the thorax and
of the lumbar and lower dorsal spine. (6) Acting from the thorax, this muscle


432
THE MUSCLES
will flex the pelvis, rotate it to the opposite side, and by means of its posterior
fibres it will act as a lateral flexor of the pelvis.
Relations. Superficially, the external oblique and latissimus dorsi; deeply, the
transversalis abdominis. Its lower margin lies for a short distance in front of the
inguinal canal, containing the spermatic cord in the male, and the round ligament
in the female. The conjoined tendon lies internally beneath these structures. The
aponeurosis of the internal oblique is also in relation with the rectus muscle, of
which it forms the sheath in the upper three-fourths of its extent.
Variations. Sometimes the muscle is crossed close to its insertion upon the ribs by
tendinous insertions, which probably represent ribs.
CREMASTER
The cremaster (fig. 285)-named from its action as a suspender of the testicle
(Kрeμaστýp a suspender, from кpeµávvvμ to hang)-is really a detached part of the
obliquus internus, forming with the fascia which connects its fibres a thin loop-
shaped band which in the male envelopes the lower part and front of the testicle
and spermatic cord. In the female it is either entirely absent, or a few fibres upon
the front of the round ligament take its place.
Origin. The upper and deep surface of Poupart's ligament about its middle
point.
Insertion. (1) The spine, and crest of the pubic bone; (2) the front of the
fascia propria or infundibuliform fascia, which envelopes the testicle and spermatic
cord.
Structure. The fibres, which differ from all other muscles in their scattered and
separate character, spring fleshy from the concavity of Poupart's ligament on the
deep aspect of the aponeurosis of the obliquus externus, in continuation of the
origin of the obliquus internus. Three main divisions may be noted:-(1) A
series of loops which pass from this origin at different heights in front of the cord
and testicle, with their convexities directed downwards, and closely connected
with the fascia propria of the testicle; finally, they collect into a narrow tendinous
band, which is attached to the spine and crest of the pubes. (2) A group of
divergent fleshy fibres, which pass from the origin downwards and inwards to
be lost upon the fascia propria. (3) A smaller group, which descend from the
tendinous insertion to be lost in a similar manner upon the front of the fascia
propria.
Between these fleshy fibres, which are often thin and difficult to recognise,
there is a layer of connective tissue, called the cremasteric fascia, which unites
them and forms one of the coverings of the testicle and cord.
Nerve-supply. The genital branch of the genito-crural, from the first and
second lumbar nerves, gives off numerous filaments which enter the muscle upon
its deep and posterior aspect.
Action.-To raise the testicle, and draw it upwards towards the external
abdominal ring. This action is involuntary, and is usually of a reflex character,
being readily excited by any irritation of the adjacent skin either of the scrotum or
thigh.
Relations.-Superficially, the external oblique aponeurosis above, the inter-
columnar fascia, dartos, and integuments below; deeply, the spermatic cord and
testicle with its fascia propria.

TRANSVERSALIS ABDOMINIS
433
3. TRANSVERSALIS ABDOMINIS
The transversalis abdominis-named from the general direction of its fibres-is
an irregularly quadrilateral curved sheet, partly muscular, partly aponeurotic.
Origin. (1) The inner surface of the cartilages of the last six ribs, close to their
junction with the ribs, by teeth which interdigitate with the attachments of the
diaphragm; (2) the strong aponeurosis called the lumbar fascia, which arises (a)
FIG. 304.-TRANSVERSALIS ABDOMINIS AND SHEATH OF RECTUS.

External intercostal
Internal intercostal
Posterior portion of
sheath of rectus
Transversalis
abdominis
Fold of Douglas
Iliacus
Transversalis fascia and
internal abdominal ring
Conjoined tendon
Poupart's ligament
Gimbernat's ligament.
bido
Serratus magnus
-Lumbar fascia
by its anterior layer from the front of the transverse processes of the five lumbar
vertebræ, (b) by its middle layer from the tips of the transverse processes of the five
lumbar vertebræ, (c) by its posterior layer from the general vertebral aponeurosis
which is attached to the spines of the thoracic, lumbar, and sacral vertebræ; (3) the
anterior two-thirds of the inner lip of the crest of the ilium; (4) the outer third
of Poupart's ligament.
Insertion. (1) the whole length of the linea alba; (2) the anterior border of
the crest of the pubes; (3) the inner end of the ilio-pectineal line for about one
inch and a half.
Structure.--Arising by short tendinous intermixed with fleshy fibres, the muscle
FF

434
THE MUSCLES
passes transversely forwards, diverging slightly to its insertion. The change from
fleshy to aponeurotic fibres is in a curved line, the upper and lower extremities of
which approach the linea alba more closely than in the central part of the muscle.
In the upper part the fleshy fibres are overlapped in front by the rectus muscle;
and at the lower border of the muscle where it terminates in a small arch, passing
over the spermatic cord or round ligament, the fleshy fibres cease just above the
middle of Poupart's ligament. The muscles of the two sides, joined as they are by
the central aponeurosis, may be looked upon as a single muscle with a central
aponeurosis, like the diaphragm; and a similar relation may be considered to
hold good between the internal oblique muscle of one side and the external
oblique of the other, each pair forming a double-bellied muscle joined by a median
aponeurosis.
In its upper three-fourths the anterior aponeurosis is closely blended with the
posterior division of the aponeurosis of the internal oblique muscle, and forms the
hinder part of the sheath of the rectus in this region. In the lower fourth the
anterior aponeurosis is blended with the undivided aponeurosis of the internal
oblique, and passes in front of the rectus muscle and the pyramidalis.
The posterior aponeurosis, or lumbar fascia, consists of strong transverse fibres.
The middle layer is the strongest, and has in its substance fibrous bands passing
outwards from the tips of the transverse processes of the lumbar vertebræ, and
continuing the series of the ribs connected with the dorsal transverse processes.
Between this middle layer and the anterior layer which springs from the front of
the tips of the transverse processes is placed the quadratus lumborum; and a
thickening of this anterior layer passing from the tips of the transverse processes
of the first and second lumbar vertebræ to the lowest rib, called the ligamentum
arcuatum externum, gives origin to a part of the diaphragm. Between the middle
and posterior layers is placed the erector spinæ muscle. This posterior layer
blends with the vertebral aponeurosis, and gives origin to the latissimus dorsi, the
serratus posticus inferior, and other muscles.
Nerve-supply. The anterior primary branches of the lower thoracic nerves and
the ilio-hypogastric and ilio-inguinal branches of the first nerve of the lumbar plexus.
The nerves as they run forward between this muscle and the obliquus internus
distribute filaments to its outer surface.
Action. The muscles of the two sides with their intervening aponeuroses form
a strong girth round the abdominal viscera, and by their contraction compress
most powerfully the contents of the abdomen.
It will thus be seen that the three layers of the transverse muscles in the
abdominal wall cross one another at various angles, one pair passing transversely
forwards, a second forwards and upwards, and a third forwards and down-
wards. The following objects are gained by this arrangement: (1) the wall
is rendered much stronger, and the probability of a hernial protrusion of any portion
of the viscera between the separated fibres of the muscles is diminished; (2) con-
traction of the wall is permitted in every direction; (3) greater approximation of the
movable boundaries of the abdominal wall is obtained by means of the obliquity
of the muscles which affect this movement. For example, two parallel bones can
have the distance between them diminished only by one half, supposing that the
muscular fibres producing this movement run perpendicularly from one bone to the
other; but if the fibres cross one another obliquely, like those of the external and
internal oblique muscles, in passing from the crest of the ilium to the lower ribs, a
much more complete approximation of the bones is effected.
Relations. Superficially, the obliquus internus, the cartilages of the lower
ribs, some small vessels, and the lower intercostal nerves; above, it is continuous
with the lower border of the triangularis sterni; below, it lies above the spermatic
cord or round ligament, and its conjoined tendon lies for a short distance beneath

QUADRATUS LUMBORUM
435
these structures; deeply, the transversalis fascia which separates it from the
peritoneum.
The sheath of the rectus is formed by the aponeuroses of the three preceding
muscles. That of the obliquus internus divides into an anterior and posterior
layer. The anterior layer blended with the aponeurosis of the obliquus externus
forms the front portion of the sheath. Above, it is attached to the cartilages of
the fifth, sixth, and seventh ribs; and internally it blends with the posterior
portion of the sheath along the linea alba. The posterior portion of the sheath is
formed by the posterior layer of the aponeurosis of the obliquus internus, which
is blended with the aponeurosis of the transversalis. Above, it is attached to the
lower edge of the cartilages of the seventh and eighth ribs, and to the ensiform
cartilage. Internally it blends with the front portion of the sheath along the
linea alba. Rather nearer the umbilicus than the pubes, the posterior portion of
the sheath becomes suddenly much thinner and weaker at the fold of Douglas,
which is a transverse line indicating that the fibres of the abdominal aponeuroses
which have down to this level formed the posterior portion of the sheath, now pass
to its front wall. Below this level the posterior portion of the sheath is formed
by a thickening of the transversalis fascia (page 436).


POSTERIOR VERTICAL MUSCLE-QUADRATUS LUMBORUM
The quadratus lumborum (fig. 286)-named from its approximately square
shape and its position in the region of the loins-is a thick quadrilateral sheet.
Origin. (1) About two inches of the inner lip of the crest of the ilium at the
junction of its middle and posterior thirds; (2) the ilio-lumbar ligament; (3) the
tips of the transverse processes of the three or four lower lumbar vertebræ.
Insertion. (1) The inner half of the lower border of the last rib; (2) the tips
of the transverse processes of the upper three or four lumbar vertebræ ; and (3) the
fibrous continuations which pass out from these transverse processes in the
substance of the middle portion of the lumbar fascia, and which represent the
abdominal ribs.
Structure. This muscle varies considerably in its structure and arrangement,
the origins from and insertions into the transverse processes differing much in
different subjects. Its origin is usually by short tendinous intermixed with mus-
cular fibres, and extends at its lower part all along the ilio-lumbar ligament, and
behind the attachment of this ligament from the inner lip of the crest of the ilium.
The fibres converge somewhat as they ascend; the outermost, passing upwards
and inwards to the middle point of the lower border of the last rib, while the
inner fibres pass vertically upwards along the tips of the transverse processes
of the lumbar vertebræ, from which they receive short tendons, and they some-
times give tendinous slips to these processes.
On the anterior and posterior
surfaces of the muscle are often seen ascending fibres from the transverse pro-
cesses, which diverge slightly before they are inserted into the lower border of the
last rib.
Nerve-supply. From the twelfth thoracic and upper lumbar nerves, by fila-
ments which enter the muscle upon its anterior surface near its inner border.
Action.-(1) It will draw downwards the last rib, and will therefore act as a
lateral flexor of the thorax as well as of the lower thoracic and the lumbar spine;
(2) it will assist in expiration by drawing down the last rib; (3) taking its fixed
point from the last rib, it will draw upwards the crest of the ilium, and so act as a
lateral flexor of the pelvis upon the thorax.
Relations. In front lie the kidney, the colon, the psoas, the lumbar arteries
and nerves, separated from it by the anterior layer of the lumbar fascia. Behind,
FF 2
436
THE MUSCLES
the middle layer of the lumbar fascia separates it from the erector spinæ, and
along its inner border are placed the intertransversales.
The transversalis fascia, which lines the interior of the muscular portion of the
abdominal parietes, is a thin layer of connective tissue. It is best marked in the
lower part of the front of the abdomen, where some of the muscular and aponeurotic
layers are deficient. Below, it is attached to the inner border of the whole length
of the crest of the ilium, and to the outer half of Poupart's ligament, where it
blends with the iliac fascia covering the iliacus muscle. Beneath the inner half of
Poupart's ligament it is somewhat thickened, and called the deep crural arch.
This is but loosely attached to Poupart's ligament, and the fascia is continued into
the thigh, where it forms the front of the sheath of the femoral vessels. Internally
to this it is attached to the free margin of Gimbernat's ligament, and behind to the
ilio-pectineal line. Further inwards it is inserted along the posterior border of the
crest of the pubes. At the back of the linea alba it is continuous with the fascia
of the opposite side. Behind the lower part of the rectus muscle it is thickened,
and takes the place of the posterior portion of the sheath from the pubes to the
fold of Douglas. Above, it becomes thin and blends with the fascia covering the
under surface of the diaphragm; and behind, it is lost in the loose fat which covers
the posterior surface of the kidneys, together with the back of the ascending and
descending colon.
About half an inch above the centre of Poupart's ligament it is perforated by
the spermatic cord in the male, and the round ligament in the female. To the
margins of the opening, which is called the internal abdominal ring, is attached a
tubular prolongation, the infundibuliform fascia, which invests the cord or round
ligament. The connection of this tube to the rest of the fascia may be compared
to the attachment of the sleeve to a coat. No opening is therefore visible from the
exterior until the sleeve-like tube has been divided.
MUSCLES OF THE BACK
The two first layers have already been described, as they belong to the groups of
muscles which pass from the thorax to the bones of the upper extremity. The third
layer consists of muscles which stretch in a nearly transverse direction from the
spinous processes of the vertebræ to the back of the ribs, viz. the serratus posticus
superior and the serratus posticus inferior.
THIRD LAYER
1. SERRATUS POSTICUS SUPERIOR

The serratus posticus superior--named from its saw-like edge and its relation
to the other serrati-is a quadrilateral sheet with a toothed outer margin.
Origin. (1) The outer surface of the lower part of the ligamentum nuchæ near
its posterior edge; (2) the spines of the last cervical and first two thoracic vertebræ,
and the supraspinous ligaments connecting them.
Insertion. The upper borders and outer surfaces of the second to the fifth ribs,
external to their angles.
Structure. The inner half is a tendinous sheet, the fibres of which run down-

SERRATUS POSTICUS SUPERIOR
437
wards and outwards, and when they have passed beyond the line of the transverse
processes they become fleshy and are inserted into the ribs by the lower borders of
the four teeth into which the muscle divides.
FIG. 305. THE THIRD AND FOURTH LAYERS OF THE MUSCLES OF THE BACK.
Complexus
Splenius capitis
Splenius colli.
Serratus posticus inferior-
Vertebral aponeurosis.
Бел

SEVENTH CERVICAL VERTEBRA
af ode lo aubr
Had and orol
laque-070 W
Serratus posticus.
inferior
TWELFTH THORACIC VERTEBRA
Obliquus internus.
TTA TAREH
Origin of latissimus.
dorsi
FIFTH LUMBAR VERTEBRA
enomniqueo C
Burlantin
aroltson auto
ficolis vis
438
THE MUSCLES
Nerve-supply. From the second and third intercostals by fine filaments which
enter the outer part of its deep surface.
Action. To raise the ribs into which it is inserted; and therefore to assist in
inspiration.
Relations. Superficially, the trapezius, levator anguli scapulæ, rhomboideus
minor and major; deeply, the vertebral aponeurosis which separates it from the
splenius and the more superficial spinal muscles; farther outwards the muscle
covers part of the external intercostals.
Variations. The slips vary in number. Sometimes it gives off a slip from its upper
border or posterior surface which goes to the levator anguli scapula, the mastoid process,
or the superior nuchal line.
2. SERRATUS POSTICUS INFERIOR
The serratus posticus inferior-named also from its outer saw-like margin,
and its position-is a quadrilateral sheet.
Origin. The spines of the two lower thoracic and two upper lumbar vertebræ.
Insertion. The lower borders of the last four or five ribs external to their
angles, except in the case of the last rib which has no angle; and as far forwards
as the costal origins of the latissimus dorsi.
Structure. More than half of the muscle is aponeurosis, which is blended with
that of the latissimus dorsi behind, and of the erector spinæ in front, and forms a
part of the vertebral aponeurosis, which blends with the posterior layer of the
lumbar fascia. The fleshy fibres are directed upwards and outwards from this
aponeurosis, arising in an oblique line which is nearer the spine above than below,
and inserted directly or with small tendinous attachments into the ribs. Each
succeeding tooth slightly overlaps, and extends farther forwards than the one
below. The middle teeth are the largest.
Nerve-supply.-Filaments from the tenth and eleventh intercostals which enter
the deep surface of the outer part of the muscle.
Action.-(1) To depress the lower ribs; (2) to fix them, so as to enable the
diaphragm to contract. It is therefore in this respect a muscle of inspiration.
Relations. Superficially, the latissimus dorsi; deeply, the erector spine with its
upward continuations, also the levatores costarum, and the external intercostal
muscles.


GENERAL ARRANGEMENT OF THE MUSCLES
ACTING UPON THE SPINAL COLUMN
THE VERTEBRAL APONEUROSIS
the
Beneath the serrati postici are arranged what may be called the muscles of the
back proper, viz. those which move the vertebral column and act chiefly upon
spines and transverse processes of the vertebræ and the parts of the skull which
are serially continuous with them. They lie for the most part in the groove on
either side of the spines of the vertebræ, and they are bound down and protected
by the strong vertebral aponeurosis which is blended below with the tendinous
origin of the latissimus dorsi, the serratus posticus inferior, and the erector spinæ.
Laterally, it is attached to the angles of the ribs. Above, it passes beneath the
tendon of the serratus posticus inferior, and is then lost in the thin fascia covering
the splenii.

SPLENIUS CAPITIS
439
The back muscles proper may be arranged according to their direction into
two great divisions, each of which contains two classes. The vertical division
consists of muscles which run between similar points of bone, and its two classes
will contain the spinales, which connect the spines of the vertebræ to one another
and to the mesial portion of the occipital bone; the transversales, which connect
the transverse processes of the sacral and lumbar regions with the transverse
processes and the adjacent portions of the ribs in the thoracic region, the articular
and transverse processes in the cervical region, and the mastoid process at the
upper end of the spinal column. The oblique division consists of muscles which
run obliquely, and contains two classes: the spino-transversales, which run
upwards and outwards from spine to transverse process, or to a point of bone
which corresponds to a transverse process, e.g. the mastoid process; and the
transverso-spinales, which run upwards and inwards from transverse process to

spine.
The action of these muscles will be easily ascertained by observing to which
class they belong. The spinales will simply extend, while the transversales
will produce lateral flexion as well as extension. The oblique, in addition to
extension and lateral flexion, will also produce rotation wherever the ligaments
and processes of the vertebræ permit of this movement.
FOURTH LAYER
The fourth layer of the muscles of the back consists of two muscles, which are
closely connected with each other, and belong to the spino-transversalis class of
the oblique division.

1 AND 2. SPLENIUS
The splenius (fig. 305)-named from orλývov a bandage, probably on account
of the way in which it crosses over and binds down the complexus and other
muscles--is a broad four-sided sheet, divided into two parts at its insertion: the
one part being the splenius capitis, and the other the splenius colli.
(1) SPLENIUS CAPITIS
Origin. (1) The lower two-thirds of the ligamentum nucha; (2) the spines of
the seventh cervical and upper two thoracic vertebræ, and the interspinous ligaments
between them.
Insertion. The outer third of the middle nuchal line of the occipital bone,
and the back part of the outer surface of the mastoid process of the temporal
bone.
Structure. Arising by a short tendinous aponeurosis, the fleshy fibres pass
upwards and outwards parallel to each other, and are inserted by short tendinous
fibres, except along the anterior border, where the tendon of insertion extends more
than an inch downwards.
Nerve-supply. The external branches of the posterior primary divisions of
the middle cervical nerves which enter the outer part of the deep surface of the
muscle.
Action. (1) To extend the head and neck; (2) to flex them laterally; (3) to
rotate the face to the same side.
440
THE MUSCLES
(2) SPLENIUS COLLI
Origin.--The spines of the third to the sixth thoracic vertebræ, and the inter-
spinous ligaments between them.
Insertion. The back of the posterior tubercles of the transverse processes of
the three or four upper cervical vertebræ.
Structure. Of parallel fleshy fibres with a short aponeurotic origin, and
inserted by small tendons, the highest of which is the largest.
Nerve-supply. The external branches of the posterior divisions of the lower
cervical nerves.
Action.-(1) To extend the upper part of the neck; (2) to flex it laterally;
(3) to rotate it to the same side.
amoo doider
Relations of the splenius.-Superficially, the sterno-mastoid, trapezius, ser-
ratus posticus superior, and the levator anguli scapula which conceals the splenius
colli in the posterior triangle of the neck. Beneath lie the complexus, trachelo-
mastoid, cervicalis ascendens, and transversalis colli.
Variations. The number of the thoracic vertebræ from which the splenii arise varies.
The splenius colli may be absent. The slip mentioned in the variations of the serratus
posticus superior may be considered to be a variation of the splenii.
FIFTH LAYER
The fifth layer consists of vertical muscles, and contains both spinales and
transversales. To the latter class belongs the greater part of the erector spinæ
and the seven muscles which either spring from it or are serially continuous
with it: viz. the ilio-costalis, accessorius ad ilio-costalem, cervicalis ascendens,
longissimus dorsi, transversalis colli, trachelo-mastoid, and the spinalis dorsi.
1. ERECTOR SPINE
The erector spine-named from its function-is a broad and very strong
membranous sheet of a triangular shape, with a layer of fleshy fibres upon
its
deep surface; and it divides in the lumbar region into three longitudinal series
of muscles which fill the greater part of the vertebral groove.
aigh
Origin. (1) The spines of the two last thoracic, all the lumbar, and the four
upper sacral vertebræ; (2) the back of the side portion of the fourth sacral
vertebra; (3) the posterior sacro-iliac ligaments, a few of these fibres being
continuous with the origin of the gluteus maximus; (4) the upper part of the
posterior superior spine of the ilium, and the posterior fifth of the iliac crest.
Insertion. It is continuous with the spinalis dorsi, longissimus dorsi, and
ilio-costalis.
Structure. A strong membranous sheet, everywhere continuous except at the
origin from the lower thoracic and upper lumbar spines, where it is partly divided
into separate tendons.

29
It breaks up into fleshy fibres in a line which stretches obliquely upwards and
inwards from the front of the iliac origin to the last thoracic spines. Fleshy fibres
also arise upon its deeper surface at a lower level, and some arise directly from
the posterior superior iliac spine and the crest under cover of the tendinous
origin.
Nerve-supply. The external branches of the posterior divisions of the lumbar
nerves which enter its deep surface.
ILIO-COSTALIS-CERVICALIS ASCENDENS
441
Action. Generally, that of extension of the lumbar spine on the pelvis; but a full
account will be given with the description of the succeeding muscles.
Relations. Superficially, the vertebral aponeurosis, with which it is blended
at its origin and for the first two inches of its course. With this aponeurosis it
therefore enters into a close relation with the lower part of the tendons of the
latissimus dorsi and serratus posticus inferior. Deeply, the multifidus spinæ,
some of the fibres of which arise from it.
The outer division extends upwards along the angles of the ribs and the trans-
verse processes of the lower cervical vertebræ, and consists of the ilio-costalis,
accessorius ad ilio-costalem, and the cervicalis ascendens. It is separated from
the middle division by the external branches of the posterior divisions of the spinal
nerves.
OUTER DIVISION
2. ILIO-COSTALIS
The ilio-costalis, or sacro-lumbalis-named from its attachment to the ilium
and ribs is an elongated muscular sheet, with a serrated outer border formed by
the insertion of its tendons into the lower ribs.
Origin. The outer portion of the erector spinæ.
Insertion. (1) The angles of all the ribs from the sixth to the eleventh ;
(2) the lower border of the last rib; (3) the tips of the transverse processes of the
lumbar vertebræ, and the fibrous processes which extend outwards from the tips of
the transverse processes of the upper lumbar vertebræ into the lumbar fascia.

3. ACCESSORIUS AD ILIO-COSTALEM
The accessorius ad ilio-costalem or ad sacro-lumbalem-named from its being
an accessory or addition to the ilio-costalis-is a narrow musculo-tendinous band
with a serrated margin on either side.
Origin. The upper border of the angles of the seventh to the eleventh ribs and
the back of the last rib.
Insertion. The back of the transverse process of the seventh cervical vertebra,
the first rib just external to its tubercle, and the angles of the second to the fifth
ribs.
4. CERVICALIS ASCENDENS
The cervicalis ascendens-named from its position in the neck and its
direction-is a still thinner musculo-tendinous band with serrated margins.
Origin. The back of the four or five upper ribs just internal to the insertion
of the preceding muscle.
Insertion. The back of the transverse processes of the fourth, fifth, and sixth
cervical vertebræ.
Structure. These three sections form a compound muscle, composed for the
most part of fusiform bellies with tendinous origins and insertions, placed in series so
that the origins of the higher slips are on a level with the insertions of those that
arise six or seven vertebræ or ribs lower down. The lowest of the series arise
directly from the muscular mass of the erector spinæ ; and the insertions of these
lower slips, especially those into the lumbar fascia and last rib, are fleshy. A part
of the tendinous origin of the slips of muscle is so closely blended that a complete
442
THE MUSCLES
separation of the muscle into its component parts is impossible. There is a
gradual diminution of the size of each component muscle and its tendons as we
trace the compound mass upwards.
FIG. 306.-THE FIFTH LAYER OF THE MUSCLES OF THE BACK.

Complexus
Trachelo-mastoid
Transversalis colli
Cervicalis ascendens.
Longissimus dorsi
Accessorius ad ilio-
costalem
Spinalis dorsi
Ilio-costalis.
Obliquus internus.
Erector spinæ.
SEVENTH CERVICAL VERTEBRA
TWELFTH THORACIC VERTEBRA
FI
FIFTH LUMBAR VERTEBRA

LONGISSIMUS DORSI-TRACHELO-MASTOID
443
Nerve-supply. The external branches of the posterior divisions of the spinal
nerves from the lower cervical nerves to the last thoracic.
Action.-(1) To extend the vertebral column, in the lower cervical, thoracic, and
upper lumbar regions; (2) to flex it laterally in these regions; (3) to depress the
ribs, and so help in expiration.
Relations. Superficially, the trapezius, rhomboidei, latissimus dorsi, the ser-
ratus posticus superior and inferior, and the two splenii; deeply, the intercostal
muscles and the levatores costarum; internally, the muscles of the middle division,
and the external divisions of the posterior spinal nerves.
MIDDLE DIVISION
The middle division extends along the back of the transverse processes of the
lumbar and thoracic vertebræ, the articular processes, and adjacent part of the
transverse processes of the cervical vertebræ, and ends at the mastoid process of
the temporal bone. It consists of the longissimus dorsi, transversalis colli, and
trachelo-mastoid.

5. LONGISSIMUS DORSI
The longissimus dorsi-named from its great length and its position in the
dorsal region-is a compound muscle forming a long band, with its surfaces directed
outwards and inwards, and an anterior margin provided with an outer and inner
row of teeth by which it is inserted.
Origin. (1) The middle part of the erector spinæ; and (2) the transverse
processes of some of the lower thoracic vertebræ.
Insertion. Externally: (1) the lower border of the back of the transverse pro-
cesses of the upper lumbar vertebræ; (2) the lower border of the ribs just external
to their tubercles. Internally: (1) The accessory tubercles of the upper lumbar
and lower thoracic vertebræ; and (2) the back of the transverse processes of the
rest of the thoracic vertebræ.
6. TRANSVERSALIS COLLI
The transversalis colli-named from its attachment to the transverse pro-
cesses and its insertion in the neck-is a similar but narrower musculo-tendinous
band.
Origin. The back of the transverse processes of the five or six upper
thoracic vertebræ, internal to the insertion of the preceding muscle.
Insertion. The posterior tubercles of the transverse processes of the second to
the sixth cervical vertebræ.
7. TRACHELO-MASTOID
The trachelo-mastoid-named from its origin, part of which is in the neck
(Tpáxnλos), and its insertion upon the mastoid process-is a similar but smaller
musculo-tendinous band.
Origin. (1) The back of the articular processes of the lower three or four
cervical vertebræ; (2) the back of the transverse processes of the four or five
upper thoracic vertebræ.
Insertion. The posterior border of the mastoid process.
—
444
THE MUSCLES
Structure of the middle division. The three parts of this division have a close
connection with one another, and a long tendinous expansion which covers the inner
and back part of the longissimus dorsi is common to it and the spinalis dorsi.
FIG. 307.-THE FIFTH LAYER OF THE MUSCLES OF THE BACK, AFTER SEPARATING
THE OUTER AND MIDDLE DIVISIONS.

Obliquus superior
Rectus capitis posticus major
Obliquus inferior
Trachelo-mastoid
Transversalis colli
Cervicalis ascendens
Accessorius ad ilio-
costalem
Ilio-costalis
12
Rectus capitis posticus minor
SEVENTH CERVICAL VERTEBRA
rob annisarguol of T
Longissimus dorsi
TWELFTH THORACIC VERTEBRA
Insertion of ilio-costalis.
upon lumbar transverse
processes
iffon ellersvant
FIFTH LUMBAR VERTEBRA
Erector spinæ
Snad anonibout-c
od (nigh0
SPINALIS DORSI
445
The association of the two upper portions of the division is so close that they are
sometimes described together under the name transversalis, the trachelo-mastoid
being called the transversalis capitis to distinguish it from that part of the muscle
which is inserted into the neck. All the upper elements of this long compound
muscle have tendinous origins and insertions.
The trachelo-mastoid portion is often found to have a tendinous intersection
crossing its fleshy fibres.
Nerve-supply. The external divisions of the posterior branches of the lower
cervical, all the thoracic, and the upper lumbar nerves.
Action.-(1) To extend the cervical, thoracic, and lumbar spine; (2) to flex it
laterally; (3) to extend and laterally flex the head, rotating the face to the same
side.
Relations. Superficially, it is covered by the latissimus dorsi, trapezius, rhom-
boidei, serratus posticus inferior and superior, and the two splenii; upon its inner
border lie the spinalis dorsi and complexus. Upon its outer lie the muscles of the
outer division and the external divisions of the posterior branches of the spinal
Beneath lie the multifidus spinæ and the semispinalis dorsi et colli.
INNER DIVISION
The inner division consists usually of a single muscle, the spinalis dorsi; but
sometimes a small muscle, the spinalis colli, continues the series into the neck.
8. SPINALIS DORSI
The spinalis dorsi-named from its attachment to the spines in the dorsal
region-is a musculo-tendinous band closely connected below with the aponeurosis
on the back of the longissimus dorsi.
Origin. The erector spinæ, and especially that part which is attached to the
two or three lower thoracic and the upper lumbar spines.
Insertion. The spines of the upper thoracic vertebræ.
Structure. Upon its posterior surface it is covered by a thick aponeurosis, from
the upper edge and anterior surface of which fleshy fibres pass almost directly
upwards, and are then inserted by means of four to eight tendons into as many of
the upper thoracic spines. They are closely blended with the tendons of the semi-
spinalis dorsi at their insertion.
Nerve-supply. The posterior branches of the thoracic nerves.
Action. To extend the thoracic spine.

Relations. Superficially, the two serrati postici, the latissimus dorsi, the
rhomboidei and splenii; externally, the longissimus dorsi; deeply, the semispinalis
dorsi and complexus.
Variations of the erector spine and its divisions.-The number of ribs or vertebræ from
which the various parts of these divisions arise, or into which they are inserted, varies
much. The insertions upon the lumbar vertebræ are often less numerous than those
described. Occasionally the longissimus dorsi receives accessory fibres from the lower
ribs. Sometimes the portion of the longissimus dorsi, which arises from the transverse
processes of the lower thoracic vertebræ, is separate from the rest of the muscle, and is
inserted into the transverse processes of some of the upper thoracic vertebræ.

446
THE MUSCLES
SIXTH LAYER
The sixth layer, or rather group, consists of four strata of oblique muscles
belonging to the class of transverso-spinales; the deepest layer being formed by a
series of small muscles which run upwards and inwards from the back of one
vertebra to that of the next above it; while the other layers run in the same
direction but less obliquely, so as to cross over the backs of several vertebræ before
reaching their insertion.
1. COMPLEXUS
The complexus, or semispinalis capitis (fig. 306)-named from the complex or
complicated arrangement of the muscular bundles which were formerly included
under this designation, viz. the complexus, trachelo-mastoid, &c.-is a musculo-
tendinous band somewhat constricted about its middle.
Origin. (1) The back of the articular processes of the cervical vertebræ from
the third to the sixth; (2) the back of the transverse processes of the seventh
cervical and the six upper thoracic vertebræ; (3) generally also by an inner head
from the spine of the seventh cervical vertebra.
Insertion. The under surface of the occipital bone between the middle and
inferior nuchal lines from the middle line for nearly two inches outwards.
Structure. Arising by tendinous slips, the fleshy fibres pass upwards and
slightly inwards, and are inserted either directly into the occiput or by a short
aponeurosis which covers the thick part of the muscle near its outer border. On
their way, the innermost fibres are intersected by a transverse tendinous band
opposite the sixth cervical spine, and this part of the muscle, being thus divided,
is often called the biventer cervicis. There is usually also a smaller tendinous
intersection higher up across the posterior surface of the muscle.
Nerve-supply. From the suboccipital, great occipital, and the internal divisions
of the posterior branches of the three or four following cervical nerves which enter
the deep surface of the muscle.
Action.-To extend the head, to flex it laterally, and to rotate the face slightly
to the opposite side.
Relations. It is covered by the trapezius and the two splenii, and it lies upon
the muscles of the suboccipital triangle and the semispinalis colli, the vertebral
artery and the anastomosis between the arteria princeps cervicis and the arteria
profunda cervicis. It is pierced by the great occipital nerve. Internally, it lies
close to the ligamentum nucha; and externally, to the trachelo-mastoid and
transversalis colli.
Variations. The inner head may arise from several of the thoracic spines as well as
that of the seventh cervical vertebra. Sometimes a second and smaller complexus runs
beneath the normal muscle from the upper thoracic vertebræ to the head.


2. SEMISPINALIS DORSI
The semispinalis dorsi-named from the fact that the inner half only of the
muscle, i.e. its insertion, is attached to the spines of the vertebræ, and from its
situation in the dorsal region-is a rather feeble compound muscle, consisting of a
series of small muscles with tendinous extremities.
Origin. The back of the transverse processes of the sixth to the tenth thoracic
vertebræ.
Insertion. The spines of the last two cervical, and first four thoracic vertebræ.
-

SEMISPINALIS DORSI
447
Structure.-Arising by long slender tendons, the fleshy fibres form a thin sheet
which runs upwards and inwards, and then breaks up again into short tendons of
insertion. Each muscle bridges over six or seven vertebræ.
FIG. 308. THE SIXTH LAYER OF THE MUSCLES OF THE BACK.

Complexus
Obliquus superior
Rectus capitis posticus major
Obliquus inferior
Multifidus spinæ
Semispinalis colli.
Cervicalis ascendens
Longissimus dorsi-
Rectus capitis posticus minor
SEVENTH CERVICAL VERTEBRA
Semispinalis dorsi
Multifidus spinæ
Levator costæ-
Longissimus dorsi-
Ilio-costalis-
-TWELFTH THORACIC VERTEBRA
Multifidus spinæ
Obliquus internus-
Lumbar fascia-
Ilio-costalis-
FIFTH LUMBAR VERTEBRA
Multifidus spinæ
448
THE MUSCLES
Nerve-supply. The internal divisions of the posterior branches of the thoracic
spinal nerves.
Action.-To extend and laterally flex the lower cervical and upper thoracic
spines. The uppermost tendons will also assist in rotating the lower part of the
neck to the opposite side.
Relations. Superficially, the spinalis and longissimus dorsi ; deeply, the multi-
fidus spinæ.
3. SEMISPINALIS COLLI
The semispinalis colli-named from the attachment of one half the muscle,
i.e. the insertion, to the spines of the cervical vertebræ-is a somewhat triangular
sheet, with a serrated base placed vertically along the transverse processes, and the
apex at the spine of the second cervical vertebra.
Origin. The back of the transverse processes of the five or six upper thoracic
vertebræ.
Insertion. The spines of the second to the fifth cervical vertebræ.
Structure. Arising by short tendons, the fleshy fibres pass upwards and inwards,
bridging over in their course five or six vertebræ, and are inserted by still shorter
tendons into the spines of the cervical vertebræ. The highest is by far the largest.
Nerve-supply. The internal divisions of the posterior branches of the lower
cervical nerves, the upper ones entering the muscle on its superficial, and the
lower on its deep aspect.
Action.-(1) To extend; (2) to flex laterally; (3) to rotate to the opposite side,
the second and following cervical vertebræ.
Relations. Superficially, the complexus, from which it is separated by branches
of the posterior cervical nerves and the anastomosis of the arteria profunda cervicis
with the arteria princeps cervicis; deeply, the multifidus spinæ.
4. MULTIFIDUS SPINE
The multifidus spine-named from its many divisions (multus, many; findo,
to cleave) is a compound muscle, fleshy and thick in the sacral and lumbar regions,
but becoming thin and more aponeurotic in the thoracic and cervical regions.
Origin. (1) The groove in the back of the sacrum, between the spines and the
elevations which represent articular processes, the posterior sacro-iliac ligaments,
and the deep surface of the tendon of the erector spinæ; (2) the mammillary
processes of the lumbar vertebræ; (3) the back of the transverse processes of all the
thoracic vertebræ; (4) the articular processes of the fourth to the sixth cervical
vertebræ, and the back of the transverse process of the seventh cervical vertebra.
Insertion. The lower borders of the spines of the vertebræ from the last
lumbar to the second cervical.
Structure. Arising by tendinous fibres superficially, but by fleshy fibres deeply,
the bundles of each element of the muscle diverge, the more superficial ones running
obliquely upwards and inwards so as to bridge three vertebræ, while the deeper ones
pass more transversely to the third, second, and in the neck, the next vertebra
above. Consequently, the more superficial fibres from one vertebra overlap the
deeper ones from some of the vertebræ above.
Nerve-supply. The internal divisions of the posterior branches of the spinal
nerves from the second cervical to the third sacral.
Action.-To extend, laterally flex, and to rotate to the opposite side, the
various parts of the spinal column.
Relations. Superficially, the erector spinæ, longissimus and spinalis dorsi, the
semispinalis dorsi and colli; deeply, the rotatores spinæ.

ROTATORES SPINE-INTERSPINALES
449
5. ROTATORES SPINE
The rotatores spinæ-named from the rotatory action which they impress upon
the spine-are small rhomboidal sheets, chiefly found in the thoracic region, where
they form a series of eleven pairs, but occasionally found also in the upper lumbar
and the lower cervical regions.
Origin. The back and upper border of the transverse process.
Insertion.
Structure.
and inwards.
The lower border of the lamina of the next vertebra above.
Sheets of parallel fibres, almost entirely fleshy, which run upwards
Nerve-supply. The internal divisions of the posterior primary branches.
Action.-To rotate to the opposite side, and also to extend and laterally flex,
the vertebra which receives its insertion.
Relations.-Superficially, the multifidus spinæ ; deeply, the ligamenta subflava.
SEVENTH LAYER
The seventh group consists of short vertical muscles, the interspinales and
intertransversales, which lie on a deep plane internal and external to the transverso-
spinales, and under cover of the longer vertical muscles which form the fifth layer
of the back.
1. INTERSPINALES
The interspinales-named from their position-are small ribbon-like muscles
which run vertically between the spines, especially in the cervical and lumbar
regions.
Origin. The upper surface of the spine of the vertebra, near its tip.
Insertion. The posterior part of the lower surface of the spine of the vertebra
above.

Structure. In the neck the bundles are attached to the two parts of the bifid
extremities of the spines from the axis downwards. In the lumbar region they
form broader bands attached to the whole length of the spines, and separated by
the interspinous ligaments.
Nerve-supply. The internal divisions of the posterior branches of the spinal
nerves.
Action.-To extend the vertebra next above.
Relations. Behind, the spinales and complexus; internally, the interspinous
ligaments; externally, the multifidus spinæ.
Variations. Occasionally they pass over one spine to be inserted upon the next but
one. The spinalis colli, when it occurs, may be looked upon as a still greater extension of
this variation.
2. INTERTRANSVERSALES
The intertransversales-named from their position between the transverse
processes are small vertical bands, also found chiefly in the cervical and lumbar
regions.
In the neck they are double, the anterior band connecting the anterior tubercles
of the transverse processes of the cervical vertebræ, and the posterior the posterior
tubercles.
In the lumbar region they are also double, an outer set connecting the adjacent
GG
450
THE MUSCLES
surfaces of the ends of the transverse processes, and an inner connecting the
accessory tubercle of one vertebra to the mammillary tubercle of the next vertebra
below. A few similar pairs of muscles may also be found in the lower part of the
thoracic region.
Structure. Fleshy, with parallel fibres.
Nerve-supply. The spinal nerves as they emerge from the intervertebral
foramina.
Action. To flex laterally the spinal column.
Relations. In the neck the anterior primary branches of the nerves come
out between the anterior and posterior intertransversales, and the posterior primary
branches emerge at the inner borders of the posterior intertransversales. They are
hidden from view by the mass of muscles attached to the transverse processes. In
the lumbar region they lie under cover of the erector spinæ and its divisions, and
they are covered in front by the psoas (fig. 286).
THE SUBOCCIPITAL MUSCLES
The suboccipital group consists of short muscles, situated in the same plane as
the preceding, but somewhat altered in their arrangement on account of the
peculiar movements of the region. They are the rectus capitis posticus major and
minor, the obliquus capitis inferior and superior, the rectus capitis lateralis.
1. RECTUS CAPITIS POSTICUS MAJOR
The rectus capitis posticus major (fig. 308)-somewhat incorrectly named from
the direction of its fibres, its position, and size-is a triangular sheet.
-
Origin. The upper surface of the spine of the axis along its side and one half
of its bifid tip.
Insertion. The middle third of the inferior nuchal line of the occipital bone.
Structure. From a narrow tendinous origin the fleshy fibres diverge as they
run upwards and outwards to a broad insertion.
Nerve-supply. A branch of the suboccipital which enters the middle of its deep
surface.
Action. To extend the head upon the neck; and to rotate the head to the
same side.
Relations.-Behind, the complexus and obliquus superior; in front, the
succeeding muscle.
2. RECTUS CAPITIS POSTICUS MINOR
The rectus capitis posticus minor (fig. 308)-named from its direction, size, and
position-is also flat and triangular.
Origin. The upper part of one half of the posterior tubercle of the atlas.
Insertion. The inner third of the inferior nuchal line of the occipital bone,
and the space immediately in front of it.
Structure.-Fleshy, and consisting of fibres which diverge in fan shape as they
pass upwards and outwards.
Nerve-supply. Branches of the suboccipital nerve which enter the outer part
of its deep surface.
Action.-To extend the head on the neck.
Relations.-Behind, the preceding muscle and complexus; in front, the
posterior occipito-atlantal ligament.

SUBOCCIPITALS
451
3. OBLIQUUS CAPITIS INFERIOR
The obliquus capitis inferior (fig. 308)-named from its direction and position
-is a fusiform sheet.
Origin. The upper part of the side of the spine of the axis.
Insertion. The lower part of the tip of the transverse process of the atlas.
Structure. Strong and fleshy, with pointed extremities, and a general direction
upwards and outwards.
Nerve-supply. The suboccipital, which sends branches to its upper border.
Action.-Chiefly to rotate the atlas, and with it the head, to the same side. It
will also help in extension and lateral flexion of the atlas upon the axis.
Relations.-Behind, the complexus and the great occipital nerve, which winds
round its lower border; in front, the posterior atlanto-axial ligament and vertebral
artery.
4. OBLIQUUS CAPITIS SUPERIOR
The obliquus capitis superior (fig. 308)-named from its direction and position
-is flat and triangular.
Origin. The back of the upper surface of the transverse process of the atlas.
Insertion. The impression immediately behind the outer half of the inferior
nuchal line of the occipital bone.
Structure. Of fleshy fibres which diverge fanwise upwards and inwards.
Nerve-supply. The suboccipital, which supplies it at the inner part of its deep

surface.
Action. To extend and slightly to flex laterally the head.
Relations.-Behind, the complexus and splenius capitis; in front, the rectus
capitis posticus major, vertebral artery, and posterior occipito-atlantal ligament.
5. RECTUS CAPITIS LATERALIS
The rectus capitis lateralis (fig. 315)-named from its direction and position-
is a quadrilateral sheet, and corresponds to the intertransversales posteriores of the
vertebræ below.
Origin. The front of the upper surface of the lateral mass of the atlas.
Insertion. The under surface of the jugular process of the occipital bone.
Structure.-Fleshy, with parallel vertical fibres.
Nerve-supply. The anterior branch of the first cervical nerve which passes out
internal to it, and supplies it from the front.
Action. To flex the head laterally.
Relations. In front, the anterior primary branch of the first cervical nerve, and
the internal jugular vein; behind, the obliquus superior and the trachelo-mastoid.
Variations. Occasionally the short muscles of this group are double. Small slips of
muscle have been observed, running from the spines of the lower cervical vertebræ, or the
ligamentum nucha to the occipital bone.
GG 2
452
THE MUSCLES
MUSCLES OF THE HEAD AND NECK
The superficial layer in this region is peculiar in that it consists of numerous
muscles contained in the connective tissue outside the deep fascia. This connective
tissue, the superficial fascia, is moderately provided with fat, and extends without
any deep connection to the adjacent regions of the thorax, arm, and back. In the
scalp it is firm and difficult to dissect on account of numerous septa which pass
through it to unite the skin to the subjacent muscular aponeurosis. In this
situation the superficial fascia is richly provided with blood by vessels which run
within it instead of beneath the deep fascia, which is their usual position in other
parts of the body.
Besides the peculiarity of their position outside the deep fascia, these muscles
are all associated in their function, viz. to produce the various movements of the
features by which the expression of the emotions is effected. They are also
peculiar in the fact that many of them decussate with each other on the way to
their insertion in the skin; and they are all supplied by the seventh pair of
cranial nerves.
SUPERFICIAL MUSCLES OF NECK AND SCALP
1. PLATYSMA MYOIDES
The platysma myoides-named from its flat expanse (platysma, a plate) and
its similarity to muscle (myoides, like muscle, for the older anatomists considered
it to be only a membrane)-is a quadrilateral sheet with a somewhat toothed
posterior border.
Origin. (1) The deep fascia of the upper part of the front of the chest and
the shoulder, and the deep cervical fascia covering the sterno-mastoid.
Insertion. (1) The outer surface of the lower border of the body of the
mandible, both on the same and the opposite side; (2) the deep surface of the skin.
from the corner of the mouth to the anterior border of the masseter muscle.
Structure.-Arising by slender bundles from the fascia covering the pectoralis
major and deltoid, in a line from the second costal cartilage to the tip of the
acromial process, the pale muscular fibres at first converge slightly until they
have crossed the clavicle. They then run parallel to each other upwards and
forwards, receiving at the posterior border of the muscle small teeth from the deep
fascia forming the sheath of the sterno-mastoid. The anterior fibres cross the
middle line half-way between the hyoid bone and the symphysis, and are inserted
into the lower border of the body of the mandible upon the opposite side of the
neck. The greater part of the rest are inserted into the outer surface of the lower
border of the mandible on the same side, but some are continued upwards and join
with the depressor labii inferioris. Still further back, a few fibres pass upwards
over the lower part of the masseter, and are inserted into the deep surface of the
skin just outside the angle of the mouth. A strong bundle of these fibres which runs
nearly transversely forwards to the corner of the mouth will be described later as
the risorius muscle. In its whole extent the muscle is closely connected with the
deep surface of the skin.
Nerve-supply. The seventh cranial nerve, by means of the inframaxillary
branch of the cervico-facial division, which supplies it from beneath at a point a
little below the angle of the mandible.
Action.-(1) To draw downwards and outwards the lower lip, by means of the

PLATYSMA MYOIDES
453
fibres which are continued upwards into the depressor labii inferioris. In trans-
verse wounds below the mandible, the division of this muscle often impairs this
movement. Duchenne has shown how important a part this depression of the
lower lip discharges in the expression of horror or extreme surprise. (2) To draw
outwards the soft parts of the side of the neck, so as to diminish pressure upon the
veins during strong inspiratory efforts. As the muscle is arched in its passage
from the clavicle to the mandible, with the concavity directed outwards, it is plain
FIG. 309. THE SUPERFICIAL MUSCLES OF THE HEAD AND NECK.

Frontalis
Orbicularis palpebrarum
Pyramidalis
Levator labii superioris
alæque nasi
Compressor narium-
Dilatator naris anterior-
Dilatator naris posterior-
Levator labii superioris
Zygomaticus minor
Levator anguli oris
Orbicularis oris
Depressor labii inferioris
Depressor anguli oris
Zygomaticus major
Platysma myoides
- Epicranial
aponeurosis
Attollens aurem
Attrahens
aurem
Occipitalis
Retrahens
aurem
Masseter
Risorius
Sterno-mastoid
aigizo
Ints
-Trapezius
that its contraction will flatten the arch and tend to lift the skin and fascia off the
vessels, in exactly the opposite manner to that by which pressure is exerted when
the concavity is upon the deep surface of a muscle. (3) It may assist feebly in
depression of the mandible; and, if that be fixed, in flexion of the head and rotation
towards the same side. This muscle covers all the front of the neck with the
exception of a narrow triangular interval, the base of which is formed by the upper
border of the sternum and the adjacent sterno-clavicular joints.
Relations. It lies immediately beneath the skin and superficial fascia, and in
454
THE MUSCLES
a lean neck the bundles are often distinctly visible through the skin, especially
when an effort is made to depress the lower lip while the teeth are clenched.
A thin band derived from the anterior part of the depressor anguli oris usually.
crosses it superficially beneath the chin (page 465). Upon its deep surface lie
the deep cervical fascia, the external jugular vein, the glandulæ concatenatæ of the
neck, the parotid and submaxillary glands, and the superficial branches of the
cervical plexus, together with the masseter, and buccinator, the muscles of the
front and side of the neck, and the pectoralis major and deltoid. Its anterior
border lies externally to the sterno-clavicular joint, and is often conspicuous in
the aged, in whom the two muscles may be seen to hang, like a dewlap, beneath
the chin, and then to divide into the two separate folds formed by their internal
borders, which run outwards and downwards towards the clavicles.
Variations. The anterior border of the muscle may be placed as far backwards as the
middle of the clavicle, and in some cases the muscle has been entirely absent. Slips have
been seen going to the side of the thyroid cartilage, the auricle or the mastoid process.
2. OCCIPITO-FRONTALIS
The occipito-frontalis-named from its two muscular bellies, which cover
parts of the occipital and frontal bones-consists of two curved muscular sheets
united by a strong aponeurosis, and is best described in three parts-viz. the
occipitalis and frontalis muscles and the epicranial aponeurosis.
(1) The occipitalis is a small quadrilateral sheet.
Origin. (1) The outer two-thirds of the superior nuchal line of the occipital
bone, and (2) a ridge upon the mastoid process.
Insertion. The posterior border of the epicranial aponeurosis, about one inch
and a half above the superior nuchal line of the occipital bone.
(2) The frontalis a curved sheet of somewhat quadrilateral shape, with a
convex upper, and a concave lower border.
Origin. The epicranial aponeurosis, about half-way between the coronal
suture and the orbital arch.
Insertion. The deep surface of the skin of the eyebrow and of that which
occupies the space at the root of the nose between the eyebrow and the middle
line.
(3) The epicranial aponeurosis forms the central tendon of the occipito-
frontalis, and its attachments will be described with the structure of the muscle.
Structure.--The occipitalis is thin and pale, and arises by short tendinous inter-
mingled with muscular fibres, and, after passing in parallel lines for about one inch
and a half upwards, it is inserted into the epicranial aponeurosis, a strong curved
sheet, which occupies the whole of the surface of the skull from the superior nuchal
lines behind to the eyebrows in front, and is continued laterally over the temporal
fascia of either side to about the level of the external auditory meatus. Above, it is
tendinous, and composed of fibres which run from behind forwards. It is thin in
front and behind, where it forms a sort of sheath to the occipitalis and frontalis
muscles; but near the median line behind it is thick where it fills up the interval
between the occipitales. Laterally, it becomes very thin, and is lost in the loose
connective tissue superficial to the temporal fascia, after having supplied their origin
to the attrahens and attollens aurem muscles. In front, a narrow triangular slip,
with the base upwards and the apex between the eyebrows, is left between the
frontales, which are larger and somewhat thicker than the occipitales. The fibres
of the frontales run in parallel bundles downwards and slightly inwards, and are
lost in the subcutaneous fat of the eyebrows; while near the middle line a small
slip is continued upon the bridge of the nose as the pyramidalis, after entering


OCCIPITO-FRONTALIS-ORBICULARIS PALPEBRARUM
455
into close relation with the deep surface of the skin at the junction of the forehead
and nose.
Nerve-supply. The occipitalis receives one of the divisions of the post-auricular
branch from the facial or seventh cranial nerve. Its filaments enter the deep
surface of the muscle close to the outer border.
The frontalis is supplied by the temporal branch of the temporo-facial division
of the facial nerve which is distributed to the deep surface near its outer border.
Action. The occipitalis draws back the epicranial aponeurosis, and with it the
scalp, which is intimately attached to its outer surface. Acting from behind, the
frontalis raises the eyebrow. If these are fixed by the contraction of the orbicularis
palpebrarum, the frontalis will draw forwards the epicranial aponeurosis and scalp.
When both occipitales and frontales contract, they raise the eyebrows to the utmost
extent, and throw the skin of the forehead into transverse wrinkles, as in the
expression of surprise or horror. At the same time, on account of the direction of
the hair-bulbs, which lie with a forward slant behind and a backward slant in front,
there will be a simultaneous tendency to lift the hair shafts, and to make them
'stand on end, like quills upon the fretful porcupine.'
When the frontalis alone contracts, taking its fixed point from above, a slight
elevation of the eyebrow is produced, as in the expression of attention. This is
also accompanied by a transverse wrinkling of the forehead.
Relations. Superficially, the epicranial aponeurosis and its muscles are in very
close connection with the skin of the scalp and forehead, being only separated from
it by granular fat which is contained in small compartments formed by fibrous
septa extending from the aponeurosis to the deep surface of the skin. In the
fat lie the hair-bulbs and blood-vessels of the scalp. Beneath, it is separated from
the pericranium and temporal fascia by very loose connective tissue.
Variations. The occipitalis may be continuous with the retrahens aurem. The fron-
talis may have insertions into the external or internal angle of the frontal bone, the nasal
process of the maxilla, or the nasal bone.

THE MUSCLES OF THE EYELIDS AND EYEBROWS

These are four in number-viz. the orbicularis palpebrarum, the tensor tarsi,
the corrugator supercilii, and the levator palpebræ superioris. To these may be
added a fifth, the frontalis, which has been described. The levator palpebræ
superioris will be described with the orbital muscles. The only part of it which is
visible in a dissection of the face is its broad expansion, which is intimately blended
with the front of the crescentic plate of condensed fibrous tissue called the upper
tarsal cartilage.
1. ORBICULARIS PALPEBRARUM
The orbicularis palpebrarum-named from the rounded shape of the majority
of its fibres (orbiculus, a little circle) and its relation to the eyelids-is an oval
sheet with a long transverse diameter and so curved as to fit the prominences and
depressions of the eyelids and the margin of the orbit.
It consists of a marginal and a central division: the former stronger and called
the orbital portion; the latter thin and pale, and called the palbebral portion.
Both have attachments to the tarsal ligaments, by which the so-called tarsal
cartilages are fastened to the margins of the orbit. The internal tarsal ligament,
or tendo oculi, is a strong flat band of fibrous tissue about a sixth of an inch long
with surfaces which look upwards and downwards. It arises from a projection upon
456
THE MUSCLES
the crest of the nasal process of the maxilla, and passes transversely outwards and
somewhat upwards in front of the lachrymal sac, to which it gives off an aponeurotic
covering. It then bifurcates into an upper and a lower division, which diverge to
be attached to the inner extremities of the tarsi, here separated by the caruncula
lachrymalis. The external tarsal ligament is undivided; it passes from the margin
of the frontal process of the malar bone transversely inwards to the extremities
of the tarsi, which at the outer commissure of the eyelids are in close contact.
The orbital portion of the orbicularis palpebrarum consists of a series of con-
centric oval loops which are attached only at the inner side of the orbit.
Origin and insertion.-(1) The lower part of the internal angular process of
the frontal bone; (2) the posterior half of the outer surface of the nasal process
of the maxilla; (3) the upper and lower surfaces of the inner half of the internal
tarsal ligament.
The palpebral portion consists of paler and shorter semielliptical fibres.
Origin. The upper and lower surfaces of the outer half of the internal tarsal
ligament, together with the adjacent part of the aponeurosis covering the lachrymal
sac.
Insertion. The upper and lower surfaces of the external tarsal ligament.
Structure. Both portions of the muscle are entirely composed of fleshy fibres.
In addition to the origin of the orbital portion at the inner part of the orbit, it
gives off processes from its circumference which blend with the adjacent muscles,
such as the frontalis and the elevator of the upper lip. Moreover, some of the
deeper fibres of the muscle decussate with the fibres of those adjacent muscles
which lie under cover of the outer loops.
The innermost fibres of the palpebral portion are shorter than the rest and,
instead of extending across the whole length of the tarsi, they terminate upon their
free margins, between the attachment of the eyelashes and the orifices of certain
glands which line the inner surface of the tarsi.
Nerve-supply. The temporal and malar branches of the temporo-facial
division of the facial nerve, which enter the outer part of the muscle upon its deep
surface.
Action.-(1) The orbital portion by its contraction draws the soft parts around
the opening of the orbit inwards and towards the palpebral aperture, raising
up a ridge which deepens the socket of the eye so as to protect the eyeball from
injury, e.g. from the blow of a fist. (2) Its upper part will lower the eyebrow, as
when the face is exposed to a strong light, or when the mind is wrapt in thought. (3)
The palpebral portion will lower the upper and raise the lower eyelid, in closure of
the eye. (4) The firm contraction of the whole muscle presses upon the eyeball,
and supports it from the evil effect of a strong expiratory effort, which by the
rush of blood into the interior of the eyeball might burst its thin-walled vessels,
and do serious harm to the delicate structures within. Thus it will be noticed that
in shouting, sneezing, or violent coughing the eyes are tightly closed. (5) By
pressure upon the lachrymal gland it is probable that the muscle influences the
secretion of tears: hence their flow during violent coughing or laughter. It will
also draw outwards and forwards the covering of the lachrymal sac, and so produce
a suction of the tears through the canaliculi into the sac.
Relations. Superficially, the skin; upon its deep surface the tarsal cartilages
and their ligaments, the palpebral ligaments and the expansion of the tendon of
the levator palpebræ superioris; the bones which bound the opening of the orbit, the
frontalis and corrugator supercilii muscles above; the temporal fascia externally;
the zygomaticus minor, levator labii superioris, and levator labii superioris alæque
nasi, below; also the supraorbital vessels and nerves, the supratrochlear nerve, the
terminal portion of the facial artery, and the palpebral branches of the infra-
orbital vessels and nerve.


TENSOR TARSI-CORRUGATOR SUPERCILII
457
2. TENSOR TARSI
The tensor tarsi-named from its supposed action upon the tarsus-is a small
muscle composed of two flat slips, which are closely connected with the preceding
muscle.
Origin. The crest of the lachrymal bone.
Insertion. The posterior aspect of the inner end of the tarsi.
Structure.-Arising as a thin muscular sheet, at the back of, and in close contact
with, the outer surface of the lachrymal sac, the muscle divides into two slips which
run behind the canaliculi, and are inserted into the edge of the eyelids near the
puncta lachrymalia.
Nerve-supply. From the infraorbital branch of the upper division of the facial
nerve, by small slips which enter the muscle near its lower border.
FIG. 310.-THE TENSOR TARSI AND CORRUGATOR SUPERCILII.

Orbicularis.
palpebrarum
Tensor tars
Corrugator supercilii
Obliquus superior
Obliquus inferior

Action.-To compress the lachrymal sac by drawing inwards and backwards the
outer part of the tendo oculi and the inner ends of the tarsi.
Relations. Internally and in front, the lachrymal sac; externally and behind,
the orbital fat from which it is separated by the capsule of Tenon.
3. CORRUGATOR SUPERCILII
The corrugator supercilii--named from its action, the wrinkling of the brow-
is a short ribbon-shaped muscle.
Origin. The inner extremity of the superciliary ridge of the frontal bone.
Insertion. The deep surface of the skin at the middle of the eyebrow.
Structure. A small wisp of fleshy fibres, closely connected with the orbital
portion of the orbicularis palpebrarum. It passes outwards, and at the same time
slightly upwards and forwards, to the under surface of this muscle, and, diverging
slightly, its fibres pass between those of the orbicularis and frontalis to their
insertion in the skin.
Nerve-supply. The temporal branch of the upper division of the facial nerve,
which enters its deep surface from the outer side.
Action.-To draw the middle of the eyebrow inwards and slightly downwards.
In the adult this causes vertical wrinkles to form between the eyebrows, and gives
a frowning aspect to the face, as when a difficulty occurs either in thought or action.
In the crying infant, the effect of its contraction is to cause dimples about the

458
THE MUSCLES
centre of the eyebrows, which may usually be observed just before the orbiculares
palpebrarum close the eyes.
Relations.
Superficially, the orbicularis palpebrarum; deeply, the frontal bone.
THE EXTRINSIC MUSCLES OF THE AURICLE
The extrinsic muscles of the auricle (fig. 309)-viz. the attollens aurem, the
attrahens aurem, and the retrahens aurem-are feeble, and almost vestigial in man.
They are closely connected with the occipito-frontalis. The largest of the three is
the attollens aurem.
1. ATTOLLENS AUREM
The attollens aurem-named from its action as an elevator of the auricle-is
a thin triangular sheet.
Origin. The epicranial aponeurosis, a short distance below the top of the
temporal ridge.
Insertion. The inner surface of the pinna of the auricle, over a space which
corresponds to the fossa of the antihelix upon its outer surface.
Structure. A thin fan-shaped sheet, consisting of muscular fibres mixed with
bands of connective tissue, which converge from above upon a flat tendon just above
the point of insertion.
Nerve-supply.-The temporal branch of the upper division of the facial nerve,
by filaments which enter the front of the deep surface.
Action.-To draw upwards the auricle.
Relations. Superficially, the skin; deeply, the temporal fascia and auriculo-
temporal nerve.
2. ATTRAHENS AUREM
The attrahens aurem-named from its action in drawing forwards the auricle-
is a smaller and very thin triangular sheet.
—
Origin. The lateral border of the epicranial aponeurosis in front of and below
the level of the preceding, with which it is usually continuous.
Insertion. The front of the inner surface of the helix.
Structure. It consists of a thin stratum of muscular fibres, intermingled with
connective tissue, lying upon the temporal fascia, and converging backwards and
downwards upon a feeble flat tendon.
Nerve-supply. The same as the preceding.
Action. To draw forwards and upwards the auricle.
Relations.-Superficially, the skin; deeply, the temporal fascia, temporal
artery, and auriculo-temporal nerve.
3. RETRAHENS AUREM
The retrahens aurem named from its action of drawing back the auricle-
consists of two muscular bands, which narrow slightly as they pass forwards to
the ear.
Origin. The upper part of the outer surface of the mastoid process of the
temporal bone.
Insertion. The inner surface of the concha.

RETRAHENS AUREM-COMPRESSOR NARIUM
459
Structure. It consists usually of darker and more distinctly muscular bands
than the two preceding muscles. They arise, one above the other, by short tendinous
fibres from the mastoid process, and pass transversely forwards to their tendinous
insertion.
Nerve-supply. The posterior auricular branch of the facial, which sends
filaments to the lower part of its deep surface.

Action.-To draw back the auricle.
Relations. Superficially, the skin; deeply, the posterior auricular artery, part
of the great auricular and the posterior auricular nerves.
THE MUSCLES OF THE NOSE
The chief muscles of the nose are three in number: viz. the pyramidalis nasi
and compressor narium, which consist of muscular fibres which pass upwards and
outwards from an aponeurosis, covering the cartilaginous part of the ridge of
the nose, and intimately connected with the under surface of the skin; and the
depressor alæ nasi. A small slip from the levator labii superioris alæque nasi is also
attached to the ala nasi; and two little muscles may sometimes be found in the
subcutaneous tissue upon the outer surface of the nostril: viz. the dilatator naris
anterior and posterior.
1. PYRAMIDALIS
The pyramidalis (figs. 309, 311)-named from its triangular shape, which is
like the side of a pyramid-is a thin triangular sheet.
Origin. The upper border of the nasal aponeurosis over the junction of the
cartilage with the lower border of the nasal bone.
Insertion. The deep surface of the skin between the eyebrows, being at this
point continuous with the inner fibres of the frontalis.
Structure. The muscular fibres form a slightly curved sheet, which wraps
round the anterior surface of the nasal bone, and is continuous with the corresponding
muscle of the other side. They converge as they pass upwards, and the outer ones
run slightly inwards as well as upwards, to their insertion.
Nerve-supply.--The infraorbital branch of the upper division of the facial, which
enters the outer part of its deep surface.
Action.-To draw downwards the skin between the eyebrows, so as to throw it
forwards into a fold, and at the same time to produce a transverse groove above
the bridge of the nose. This gives to the face a stern, aggressive, or fierce
expression.
Relations. Superficially, the skin; and deeply, the nasal bone.
Variation. This muscle is sometimes absent.
2. COMPRESSOR NARIUM
The compressor narium (figs. 309, 311)-named from its supposed action as a
compressor of the nostrils-is a triangular sheet, the base of which is attached to
the nasal aponeurosis above mentioned.
Origin. The sides of the nasal aponeurosis.
Insertion. (1) The lower and front part of the canine fossa of the maxilla;
(2) part of its fibres are continued into those of adjacent muscles, especially the
levator labii superioris alæque nasi, and the levator anguli oris.
460
THE MUSCLES
Structure. Arising from the side of the aponeurosis in a vertical line about
half an inch from the ridge of the nose, the fibres of the muscular sheet converge
as they pass backwards, outwards and downwards, to a narrow band just above and
behind the ala nasi. Here they are partly attached to the maxilla, and partly
they pass into the adjacent muscles.
Nerve-supply. The infraorbital branch of the upper division of the facial
nerve, which sends filaments to the deep surface of the muscle near its upper
border.
Action.-(1) To depress slightly the cartilaginous ridge of the nose; (2) to
throw into vertical wrinkles the side of the nose, as when a bad smell is perceived;
(3) to assist the adjacent muscles in dilating the nostril and drawing up parts of
the upper lip.
Relations. Superficially, the skin and levator labii superioris alæque nasi;
deeply, the cartilages of the nose.
3. DEPRESSOR ALE NASI
The depressor alæ nasi (fig. 311)-named from its action upon the cartilage of
the nostril--is a small triangular sheet.
Origin. The incisive fossa of the maxilla.
Insertion. (1) The lower and back part of the cartilage of the ala nasi; (2) the
adjacent part of the lower border of the cartilaginous septum nasi.
Structure. Its muscular fibres diverge upwards and outwards from their
origin.
Nerve-supply.-Small filaments from the buccal branch of the lower division
of the facial nerve, which enter the muscle near its outer border.
Action. To draw downwards and inwards the alar cartilage..
-
Relations. Superficially, the orbicularis oris; deeply, the maxilla. It is also
closely connected with the fibres of the previous muscle and the elevators of the
upper lip.
4. LEVATOR LABII SUPERIORIS ALÆQUE NASI
This muscle will be described with the MUSCLES OF THE MOUTH.
5. DILATATOR NARIS ANTERIOR
The dilatator naris anterior (fig. 309)-named from its action and position-
is a small quadrilateral sheet.
.
Origin. The lower edge of the lateral cartilage of the nose.
Insertion. The deep surface of the skin covering the ala nasi.
Structure. A thin stratum of muscle, which may occasionally be found passing
downwards upon the upper part of the alar cartilage.
Nerve-supply. The infraorbital branch of the upper division of the facial
nerve.
Action. To dilate the nostril, e.g. in the expression of anger, or in hard
breathing.
Relations. Superficially, the skin below and the compressor narium above;
deeply, the cartilages of the ala.

ORBICULARIS ORIS
461
6. DILATATOR NARIS POSTERIOR
The dilatator naris posterior (fig. 309)--named from its action and position-
is a similar sheet of somewhat quadrilateral shape.
-
Origin. (1) The edge of the nasal aperture of the maxilla; and (2) the outer
surface of the sesamoid cartilages of the nose.
Insertion. The skin over the posterior and lower part of the alar cartilage.
Structure. A thin stratum of parallel muscular fibres running forwards and
downwards.
Nerve-supply. The infraorbital branch of the upper division of the facial
nerve.
Action.-To dilate the nostril.
Relations. Superficially, the skin and levator labii superioris alæque nasi;
deeply, the sesamoid cartilages.
MUSCLES OF THE MOUTH

The muscles of the mouth consist, firstly, of the orbicularis oris, which is
the sphincter surrounding the aperture; and secondly, of the bands which radiate
from this, as a centre, to their origin upon the adjacent facial bones. These may
be grouped into three sets: viz. (1) the transverse series, which radiate transversely.
This consists of only one pair of muscles, the buccinators. (2) The angular series,
which pass from above or below to the corner of the mouth. (3) The labial
series, which pass nearly vertically either downwards or upwards to the lips, and
chiefly to their inner half.
A fourth series may be added, which have no special connection with the mouth,
viz. two nearly vertical muscles close to the middle line, which radiate from an
origin close to the mouth. Of these, one has already been described, the depressor
alæ nasi; the other arises from the lower jaw, the levator menti.
The muscles might also be arranged according to their stratification, for they
form two, and, in some parts, three layers over the greater part of this region.
1. ORBICULARIS ORIS
The orbicularis oris-an unpaired muscle, named from its shape and situation-
is an oval sheet with the long axis placed transversely, and its fibres arranged round
a transverse central aperture. Like the orbicularis oculi, the muscle may be divided
into an internal or labial portion, and an external or facial. The first part,
which is superficial, has no bony connection, except through the medium of the
adjacent muscles with which it is closely blended. The second, which is deep and
which forms part of the third layer of the facial muscles, has the following small
bony attachments.
Attachments to bone.-(1) Naso-labial slips from the back of the lower part of
the cartilage of the septum of the nose; (2) the incisive fossa of the maxilla just
above the socket of the lateral incisor tooth; (3) the incisive fossa of the mandible,
below the sockets of the lateral incisor and canine teeth.
Structure. The orbicularis oris consists of three sets of fibres, which are in
their direction approximately transverse, vertical, and sagittal or antero-posterior.
The transverse set form the most conspicuous part of the muscle; they are
continuous on either side with the fibres of the buccinator, and they constitute the

462
THE MUSCLES
greater part of the fine smooth bundles which lie beneath the red skin of the pro-
labium, and are called the labial portion of the muscle. The vertical fibres are
derived from the elevators and depressors of the lips, including the zygomatici ; they
form the superficial part of the facial portion, and they interlace with the trans-
verse fibres. Many of them pass round the corners of the mouth and become
transverse; those arising from the maxilla and its vicinity passing to the lower
lip, while those from the mandible go to the upper. The sagittal or antero-
posterior fibres pass directly or somewhat obliquely from before backwards between
the transverse fibres, and unite the skin to the mucous membrane. They are
found chiefly in the labial portion of the muscle. The two naso-labial slips pass
side by side vertically downwards to the upper part of the muscle, their position.
being indicated upon the surface by two small vertical ridges which descend from
the columna nasi on either side of the median groove of the upper lip. The fleshy
slips from the maxilla and mandible-the musculi incisivi, as they are called-pass
outwards and forwards to join the deep surface of the transverse fibres near the
corners of the mouth.
Nerve-supply.-The buccal and supramaxillary branches of the lower division.
of the facial, which enter the facial part of the muscle near its outer border.
Action.-(1) To bring together the lips and to oppose all the other muscles
which converge upon the mouth, and tend to draw it open in various directions.
It thus acts negatively, and prevents the expression of any emotion, as when
the lips are pursed up. If the upper fibres alone act, the upper lip will be drawn
downwards; if the lower, the lower lip will be drawn upwards. If the fibres of
the labial portion contract strongly, the corners of the mouth are approximated.
(2) To shoot out the lips: this will chiefly depend upon the contraction of the
facial portion and the musculi incisivi. (3) To press the lips against the teeth: the
plane of the muscle being curved, with the concavity against the arches formed
by the front teeth, its contraction will carry the food backwards into the oral
cavity.
Relations. In front of the labial portion is the bright red skin of the prolabium;
and in front of the facial portion lie the angular and labial series of muscles,
together with some subcutaneous fat.
Upon the deep surface lies the mucous membrane of the mouth, separated from
the muscular fibres by the mucous and small salivary glands, together with the
superior and inferior coronary arteries.
TRANSVERSE MUSCLES OF THE MOUTH
This group comprises only the buccinator.
BUCCINATOR
The buccinator-named from its action, as it is the muscle used by the
trumpeter (buccinator)-is a somewhat oval sheet of muscular fibre, distinct in its
origin, but blending in front with the orbicularis oris. It forms a part of the
third stratum of the facial muscles.
Origin. (1) The outer surface of the alveolar process of the maxilla, above
the last two molars; (2) the anterior border of the pterygo-maxillary ligament,
a fibrous band or raphé extending from the hamular process of the internal
pterygoid plate of the sphenoid bone to the back of the mylo-hyoid ridge of the
mandible; (3) the outer surface of the alveolar process of the mandible below the
last two molars.

BUCCINATOR
463
Insertion.
The outer part of the orbicularis oris.
Structure. It rises by fleshy fibres which run forwards in four sets. The
upper set pass directly into the facial portion of the orbicularis oris which belongs
to the upper lip; the next pass downwards and forwards to that which belongs to the
lower lip; the third upwards and forwards, decussating with the second set to join
the lower part of the orbicularis in the upper lip. Finally, a fourth set which pass
from the mandible to the lower part of the facial portion of the orbicularis oris
belonging to the lower lip.
FIG. 311.-THE DEEPER LAYER OF THE MUSCLES OF THE FACE AND NECK.

Corrugator
supercilii
Pyramidalis
Levator labii
superioris
alæque nasi
Levator labii
superioris
Compressor
narium
Levator anguli
oris
Naso-labialis
Depressor alæ
nasi
Orbicularis oris
Buccinator
Depressor
anguli oris
Depressor labii
inferioris
Levator menti
Mylo-hyoid
Anterior belly
of digastric
Thyro-hyoid
Omo-hyoid
Sterno-hyoid
-Temporalis
Zygomaticus
major
Masseter
Posterior belly
of digastric
Splenius capitis
Stylo-hyoid
Sterno-mastoid
Levator anguli
scapulæ
Scalenus anticus
Scalenus
medius
Omo-
hyoid
Nerve-supply. The buccal branch of the lower division of the facial, which
sends filaments into the back part of its outer surface; it is also pierced by the buccal
branch of the inferior maxillary division of the fifth nerve on its way to supply the
mucous membrane lining the cheek.
Action.-(1) To draw outwards the corner of the mouth, widening it and
pressing the lips against the teeth; (2) to diminish the concavity of the cheek,
464
THE MUSCLES
compressing the air contained in it, as in using the blowpipe or playing the cornet;
or forcing inwards the food when, in mastication, any portion of it has escaped
into that part of the mouth which is external to the bicuspids and molar teeth.
Relations. Superficially, the skin, subcutaneous fat, Steno's duct, the zygo-
maticus major, risorius, a large mass of fat (the buccal fat-pad) which separates
the buccinator from the masseter, and a layer of deep fascia continuous with that
which covers the upper part of the pharynx; deeply, the mucous membrane of
the mouth. The upper part of the muscle is perforated by Steno's duct. The
buccinator is almost continuous behind with the superior constrictor, from which
it is only separated by the tendinous intersection of the pterygo-maxillary ligament.
ANGULAR MUSCLES OF THE MOUTH
The angular series are four in number: viz. the zygomaticus major, levator
anguli oris, risorius, and depressor anguli oris. Two descend to the corner of
the mouth obliquely from above, one runs almost horizontally forwards, and one
ascends from below. They blend at the corner of the mouth, and form there a
thick muscular mass, behind which is a depression filled up with the fat covering
the buccinator. In a lean face this depression is often very conspicuous, and
in some faces its position is indicated by a dimple when the zygomaticus major
contracts.
d
1. ZYGOMATICUS MAJOR
The zygomaticus major-named from its origin from the zygoma and its size-
is ribbon-shaped, and belongs to the first layer of the muscles.
Origin. The outer surface of the malar bone near the zygomatic suture.
Insertion. The deep surface of the skin, and the subcutaneous tissue at the
outer extremity of the upper lip, and just external to the commissure of the lips.
Structure. Arising by short tendinous fibres, the muscle forms a fleshy band
which passes downwards and forwards to the meeting-point of the angular muscles
at and external to the angle of the mouth, where it blends with the orbicularis oris
and the other angular muscles, its outermost fibres passing into the outer fibres of
the depressor anguli oris.
Nerve-supply. The infraorbital branch of the upper division of the facial
nerve, which enters the middle of its deep surface.
Action.-To draw upwards and outwards the corners of the mouth, as in
smiling or laughter. When it is strongly contracted, it throws into prominence
the soft parts of the cheek in front of the malar bone, raises the lower eyelid, and
produces 'crow's-feet,' as the wrinkles are called which radiate outwards from the
outer canthus. When both muscles act together, the mouth is widened, and the
upper lip raised so as to show the upper teeth, in what is called a 'broad grin.'
Relations. Superficially, the skin; deeply, the buccinator and facial part of
the orbicularis oris, the facial and transverse facial arteries, the facial vein, and some
branches of the facial nerve.
2. LEVATOR ANGULI ORIS
The levator anguli oris-named from its action upon the corner of the mouth
-is a triangular sheet and belongs to the second stratum of the facial muscles.
Origin. The canine fossa of the maxilla.

RISORIUS-DEPRESSOR ANGULI ORIS
465
Insertion. The deep surface of the skin, and the subcutaneous tissue, close
to the corner of the mouth.
Structure.-Arising muscular from its broad origin above the canine and
bicuspid teeth, the fibres converge in a downward and outward direction, and blend
with the other angular muscles outside the corner of the mouth.
Nerve-supply. The infraorbital branch of the upper division of the facial at
the outer part of the anterior surface.
Action.-To raise the corner of the mouth, but at the same time to draw it
inwards.
Relations. Superficially, the zygomaticus minor and levator labii superioris,
the infraorbital vessels and nerves; deeply, the facial portion of the orbicularis
oris.
3. RISORIUS
The risorius-named from its supposed action in laughter-is flat and ribbon-
shaped, and belongs to the superficial sheet of muscles, being a part of the platysma
myoides, and often very small and ill-developed.
Origin. The subcutaneous tissue overlying the deep fascia which covers the
masseter and parotid gland.
Insertion. The subcutaneous and muscular tissue external to the angle of the
mouth.
Structure. It is a band of parallel fibres which runs transversely forwards
from the upper and posterior part of the platysma to the corner of the mouth.
Nerve-supply. The buccal branch of the lower division of the facial nerve
which enters it from beneath.
Action.-To widen the mouth by drawing its corner directly outwards. It is not
used in the expression of pleasure like the zygomaticus major, but it gives a strained
painful expression to the features, such as is seen in tetanus, and called the risus
sardonicus.'
Relations. Superficially, the skin and subcutaneous fat; deeply, the masseter
and buccinator, the facial artery and vein, and branches of the facial nerve.
✓
4. DEPRESSOR ANGULI ORIS
The depressor anguli oris-named from its action upon the corner of the
mouth-is a triangular sheet, and belongs to the superficial layer of facial muscles.
Origin. The outer aspect of the lower border of the body of the mandible and
the external oblique line below the canine, bicuspid, and first molar teeth.
Insertion. The subcutaneous connective tissue, and the muscular mass external
to the corner of the mouth.
Structure. Its fibres, arising fleshy, converge upwards and inwards, and, having
diminished to a narrow band, join the general muscular mass at the corner of
the mouth, some of them being continued upwards into the levator anguli oris,
and the most external into the zygomaticus major.
The fibres which form the inner border of the muscles are often continued
downwards below the mandible, and form with those of the other side a band, partly
muscular and partly fibrous, which, lying beneath the platysma myoides, supports
and compresses the subcutaneous fat below and behind the prominence of the chin.
When there is much subcutaneous fat, the absence of this support gives rise to a
considerable prominence behind this band, and forms what is called a double chin.'
Nerve-supply. The supramaxillary branch of the lower division of the facial
nerve, which sends filaments to the back part of its deep surface.
HH

466
THE MUSCLES
Action.-To draw downwards and somewhat outwards the angle of the mouth,
giving an expression of sorrow to the face, making the individual look down in the
mouth.'
Relations. The skin superficially; deeply, the depressor labii inferioris and
inferior coronary artery.
LABIAL GROUP OF MUSCLES
The labial set consist of three muscles, which form a continuous sheet and
might fairly be included under one name, passing downwards from the maxilla;
and a single muscle passing upwards from the mandible. Both sets are inserted
into the lips, and especially into that part of them which intervenes between the
middle line and a point half way between this and the corner of the mouth.
The upper set is formed by the levator labii superioris alæque nasi, the levator
labii superioris, and the zygomaticus minor; the lower set by the depressor labii
inferioris.
1. LEVATOR LABII SUPERIORIS ALEQUE NASI
The levator labii superioris alæque nasi-named from its action as an elevator
of the upper lip and the nostril-is a somewhat triangular sheet, bifurcating
below at the base which corresponds to the insertion of the muscle. It belongs to
the superficial sheet of facial muscles.
Origin. The anterior half of the outer surface of the nasal process of the
maxilla.
Insertion (1) The deep surface of the skin which covers the lower part of the
ala nasi; (2) the deep surface of the skin, and the general muscular mass, of the
inner half of the upper lip.
Structure. Arising fleshy, its fibres diverge somewhat as they pass downwards;
they then decussate with those of the orbicularis oris close to the prolabium.
Nerve-supply. The infraorbital branch of the upper division of the facial
nerve, which sends filaments to the outer part of the deep surface of the muscle.
Action.-(1) To raise and dilate the nostril; (2) to raise the inner half of the
upper lip.
Relations. Superficially, the skin and orbicularis palpebrarum; deeply, the
compressor narium and levator anguli oris.
2. LEVATOR LABII SUPERIORIS
The levator labii superioris-named from its action-is a nearly square sheet,
and it belongs to the superficial layer of muscles.
Origin. The front of the maxilla just below the rim of the orbit.
-
Insertion. The deep surface of the skin and the subjacent muscular tissue near
the upper edge of the inner half of the upper prolabium.
Structure.-Its fibres, arising fleshy, descend parallel to one another and almost
vertically to their insertion, where they interlace with the fibres of the orbicularis
oris. It frequently receives at its outer border some bundles of fibres from the
orbicularis palpebrarum.
Nerve-supply. The infraorbital branch of the upper division of the facial
nerve, which sends filaments to the outer part of its deep surface.
Action.-To raise the inner half of the upper lip. This muscle, with its two
fellows, the preceding and following, is especially used in the expression of grief,

ZYGOMATICUS MINOR-DEPRESSOR LABII INFERIORIS 467
and to some extent of anger also, as when the lip is raised and somewhat everted
so as to show the canine tooth. In crying, the action of these muscles is strongly
displayed, for when the eyes are closed by the orbicularis palpebrarum, at the same
time the mouth is made four-square by the elevation of the inner half of the lip, while
the outer half is drawn down by the depressor anguli oris.
Relations.-Superficially, the skin and orbicularis palpebrarum; deeply, the
levator anguli oris, the infraorbital vessels and nerves.

3. ZYGOMATICUS MINOR
The zygomaticus minor-named from its association with the zygomaticus
major and its smaller size-is a small ribbon-shaped band, often absent, and
belonging to the superficial sheet of facial muscles.
Origin. The lower part of the front of the malar bone close to its junction
with the maxilla.
Insertion. The deep surface of the skin and the subjacent muscular tissue at
a point upon the upper border of the prolabium of the upper lip about midway
between the middle line and the outer corner of the mouth.
Structure.-Arising fleshy, the small band of parallel fibres which is upon its
inner margin closely connected with the preceding muscle, passes downwards and
inwards to its insertion, which interlaces with the fibres of the orbicularis oris.
Nerve-supply. The infraorbital branch of the upper division of the facial
nerve, which sends filaments to the deep surface of the muscle.
Action. To raise and somewhat evert the part of the upper lip to which it is
attached.
Relations. Superficially, the skin and orbicularis palpebrarum; deeply, the
levator anguli oris, facial portion of the orbicularis oris, and the infraorbital branch
of the facial nerve.
✓ 4. DEPRESSOR LABII INFERIORIS
The depressor labii inferioris, or quadratus menti-named from its action, or
shape, and connection with the chin (mentum)-is a nearly square sheet, and
belongs to the second layer of the facial muscles.
Origin. The outer aspect of the lower border of the body of the mandible below
the canine and bicuspid teeth.
Insertion. The deep surface of the skin and the subjacent muscular mass along
the lower edge of the prolabium of the lower lip.
Structure. It consists of parallel muscular fibres, many of them continuous
with those of the platysma myoides, which pass upwards and inwards to inter-
lace with the fibres of the orbicularis oris along the line above mentioned. The
inner margins of the muscles of the two sides meet above in the middle line.
Nerve-supply. The supramaxillary branch of the lower division of the facial
nerve, which sends filaments to its deep surface near its outer border.
Action.-To draw down and somewhat evert the lower lip.
Relations. Superficially, the skin and the depressor anguli oris; deeply, the
facial portion of the orbicularis oris, the mental vessels, and nerve.
HH 2

468
THE MUSCLES
MUSCLES RADIATING FROM THE MOUTH
The two muscles which radiate from the mouth are the depressor alæ nasi and
the levator menti.
↓
1. DEPRESSOR ALE NASI
The depressor alæ nasi has been described with the muscles of the nose.
2. LEVATOR MENTI
The levator menti, or levator labii inferioris-named from its action-is a short,
thick, and somewhat fan-shaped muscle, belonging to the second layer.
Origin.--The incisive fossa of the mandible, below and a little internal to the
attachment of the incisivus inferior of the orbicularis oris.
Insertion. The subcutaneous tissue just above the point of the chin.
Structure. Arising fleshy, its fibres diverge slightly as they pass downwards and
inwards to meet in the middle line with those of the opposite side just below a
pellet of fat which lies beneath the skin at a short distance above the point of the
chin.
Nerve-supply. The supramaxillary branch of the lower division of the facial
nerve, which terminates in this muscle.
Action. To draw upwards the skin covering the prominence of the chin, and
to elevate and shoot out the lower lip. It has been sometimes called the musculus
superbus, from the haughty and contemptuous expression which it produces when
it acts at the same time with the depressor anguli oris. A slighter contraction,
however, gives the mouth an expression of firmness and decision.
-
Relations. Superficially, the mucous membrane of the mouth and the facial
portion of the orbicularis oris above, the subcutaneous fat below; deeply, the
mandible.

MUSCLES OF MASTICATION
The muscles of mastication form an independent group, four in number,
occupying the back part of the side of the face, and the temporal and zygomatic
fossæ, and consisting of the masseter, the temporal, with the external and internal
pterygoid muscles. The temporal muscle is covered by a strong membrane, the
temporal fascia, which, arising from the temporal ridge, is attached below to the.
upper border of the zygoma, after first dividing into two lamina which go to the
outer and inner aspects of this border, and contain between them a small quantity
of fat. From the zygoma downwards, the masseteric fascia is continued to the
posterior and inferior borders of the ramus of the mandible, enveloping the
masseter muscle. Closely connected with this is the parotid fascia which
envelops this gland, extending backwards from the masseteric fascia to that part
of the deep cervical fascia which covers the upper portion of the sterno-mastoid
muscle; covering also the deep surface of the gland, and giving off a process called
the stylo-maxillary ligament, which, running from the styloid process to the angle
of the mandible, separates the parotid and submaxillary glands.

MASSETER-TEMPORAL
469
1. MASSETER
The masseter (fig. 311)-named from the Greek word uaooάouau to chew-is a
strong quadrate sheet, consisting of two layers.
Origin. The superficial layer, from the lower border of the malar bone, and
the lower border of the anterior two-thirds of the zygomatic arch; the deep layer, from
the lower border of the posterior third of the zygomatic arch, and the whole of its
inner surface.
Insertion.-Superficial layer, into the lower half of the outer surface of the
ramus of the mandible; the deep layer, partly with the superficial layer, and partly
into the upper half of the outer surface of the ramus of the mandible.
Structure. The origin and insertion are by tendinous bands intermingled in
multipenniform fashion with fleshy fibres. The fibres of the superficial sheet are
directed obliquely downwards and backwards; those of the deep sheet almost
vertically downwards, and they are much shorter than the superficial fibres. The
two sheets blend closely in front, but are separate behind, where the muscle forms
a sort of pocket closed above at the origin and below at the insertion, as well as in
front, but open behind.
Nerve-supply. The masseteric branch of the motor division of the inferior
maxillary nerve, which enters the deep surface of the muscle just below the
zygoma.
Action. To close the jaw, and by its superficial sheet to draw it slightly
forwards. In closing the jaw it acts with less mechanical disadvantage than is
usual with muscles. When the pressure to be overcome is exerted upon the back
teeth, the arm of the lever upon which the power acts is almost as long as that
which intervenes between these teeth and the fulcrum. This fulcrum is not at
the temporo-maxillary joint, but at a point below the neck of the mandible, cor-
responding very nearly to the lower attachment of the internal lateral ligament.
Moreover, the resultant force of the muscle, acting as it does upwards and forwards,
is perpendicular to the lever, which may be roughly described as a bar extending
downwards and forwards from the neck of the mandible to the point of the chin.
Relations. Superficially, the parotid gland and its duct, the platysma
myoides, the risorius and the masseteric fascia, the transverse facial vessels, the
facial vein, the upper and lower divisions of the facial nerve; deeply, the buccal
fat-pad which separates it from the buccinator, a small part of the temporal muscle,
and the ramus of the mandible.
2. THE TEMPORAL MUSCLE
The temporal muscle-named from its attachment to the temple (=tempus)-is
a thick, somewhat triangular sheet; more correctly it may be described as forming
the quadrant of a circle.
Origin. (1) The whole of the temporal fossa, from the lower ridge of that
name to the pterygoid ridge, with the exception of a small part close to the outer
wall of the orbit, which is occupied by fat; (2) the inner surface of the temporal
fascia down to its lower attachment to the zygomatic process, from the inner
surface of which some of its fibres also sometimes arise.
Insertion. The point, posterior border, and the whole of the inner surface of
the coronoid process of the mandible, down to the last molar tooth.
Structure. The bones of the temporal fossa and the temporal fascia form a
pouch, open downwards, from which the fleshy fibres of the muscle converge,
470
THE MUSCLES
the middle fibres running downwards, the anterior downwards and backwards, the
posterior almost transversely forwards, to be inserted below upon both faces of a
flat tendon which, becoming free of flesh on the outer surface first, embraces the
point and borders of the coronoid process.
Nerve-supply. The two or three deep temporal branches of the motor portion
of the inferior maxillary nerve, which enter the lower part of its deep surface.
Action. To close the jaw; its posterior fibres will also draw it backwards
after the other muscles have protruded it. This muscle, like the masseter, has to
FIG. 312.-THE TEMPORAL MUSCLE.

Temporal
Buccinator.
contend with very little mechanical disadvantage, power being of more importance
in mastication than speed.
Relations. Superficially, the temporal fascia which separates it from some of
the auricular muscles, the sides of the epicranial aponeurosis, the auriculo-temporal
nerve, and the upper branches of the facial nerve; the zygoma and a small part
of the masseter. Deeply, the temporal fossa, and the external pterygoid muscle.
At its posterior border it is crossed by the masseteric nerve and vessels.
3. PTERYGOIDEUS EXTERNUS

The pterygoideus externus-named from its attachment to the pterygoid
process of the sphenoid bone, and its relation to the companion muscle-consists
of two thick triangular sheets, the one lying in a horizontal, and the other in a
vertical plane.
Origin. Upper head: the under surface of the great wing of the sphenoid
bone, internal to the pterygoid ridge, and external to the foramen ovale and
foramen spinosum. Lower head: All the outer surface of the external pterygoid
plate, except a small strip at its lower and front part.

PTERYGOIDEUS EXTERNUS
471
Insertion. Upper head: (1) The front of the interarticular fibro-cartilage of
the temporo-maxillary joint; (2) the adjacent portion of the capsular ligament;
(3) the upper part of the front of the neck of the condyle of the mandible. Lower
head: The pit in the front of the neck of the condyle.
Structure. Arising by fleshy fibres, which are closely connected at the ptery-
goid ridge with part of the temporal muscle, the upper head forms a fan-shaped
sheet which passes backwards and slightly outwards to its insertion, which is by
short tendinous fibres blending below with those of the lower head. The lower
and much stronger head is at first separated from the upper by a small chink,
which may give passage to the internal maxillary vessels. It arises fleshy, converges
backwards, outwards, and somewhat upwards, and is inserted by short tendinous
fibres.
Nerve-supply. The external pterygoid branch of the motor division of the
inferior maxillary nerve, which divides into filaments entering its deep surface.
FIG. 313. THE PTERYGOID MUSCLES.
External pterygoid
Internal pterygoid-
Hame
7797
το γίασε
Action.-(1) To draw forwards the ramus of the mandible, and the inter-
articular fibro-cartilage; (2) to draw them inwards. The combination of these
two movements produces the oblique movement of the lower molar teeth of one
side, forwards and inwards with respect to the upper molars which are their
opponents. It should be observed also that this inward movement of one side is
the agent by which the ramus of the opposite side is moved outwards. (3) To
assist in opening the mouth by depression of the lower jaw. As the transverse
axis of this movement passes through the mandible at two points situated below
the necks of the rami, it follows that a forward movement of the condyles and
necks will assist in the backward movement of the angles and body which accom-
panies the depression of the mandible.
472
THE MUSCLES
Relations. Superficially, the anterior fibres of the internal pterygoid, the
temporal muscle, and, at a little distance, also a small part of the masseter; deeply,
the internal pterygoid muscle, the internal maxillary vessels (unless, as sometimes,
they pass across the outer surface of the lower head), the middle meningeal and
inferior dental vessels, with the masseteric and posterior deep temporal nerves passing
behind or through the attachment of the upper head; the buccal and anterior deep
temporal nerves running between the two heads; the lingual gustatory and inferior
dental nerves beneath the lower head.
Variations. Muscular fibres are frequently found upon the deep surface of the external
pterygoid, running from the back of the external pterygoid plate to the spine of the
sphenoid, or the vaginal process of the temporal bone.
4. PTERYGOIDEUS INTERNUS
The pterygoideus internus-named from its origin and relative position-is a
thick quadrilateral sheet.
Origin. (1) The whole of the inner surface of the external pterygoid plate. (2)
A small triangular area, consisting of the outer surface of the tuberosity of the
palate bone, and a small strip in front belonging to the maxilla, and one behind
belonging to the external surface of the external pterygoid plate.
Insertion. The lower half of the internal surface of the ramus of the mandible,
including the adjacent parts of its lower and posterior borders, and extending as
high as the mylo-hyoid ridge and inferior dental canal.
Structure.--Arising fleshy, the fibres run parallel to one another, downwards,
backwards, and outwards, to be inserted partly directly into the mandible, and
partly in multipenniform fashion, like those of the masseter, into the tips and sides
of fibrous septa, which, passing upwards from the periosteum of the mandible,
separate the muscular bundles from one another.
Nerve-supply. The internal pterygoid branch of the motor division of the
inferior maxillary, which enters the deep surface near its posterior border.
Action. (1) To close the jaw. The same remarks which were made with
respect to the very small loss of mechanical advantage in the masseter muscle
apply to this muscle. (2) When closed it will draw the jaw forwards; and also
(3) it will help the external pterygoid in drawing the ramus of its own side towards
the middle line.
Relations. Superficially, the external pterygoid muscle, the internal lateral
ligament, the internal maxillary vessels, the inferior dental and lingual nerves;
deeply, the tensor palati and superior constrictor of the pharynx, the stylo-hyoid
and posterior belly of the digastric, the submaxillary gland.


THE MUSCLES AND FASCLE OF THE FRONT
OF THE NECK
The platysma myoides has been already described (page 452) with the muscles
of expression.
The muscles of the neck which lie beneath it are surrounded by a layer of deep
fascia, called the cervical fascia. This is a strong tubular membrane, attached
above to the lower border of the mandible, the parotid fascia, the upper part of
the mastoid process, and the superior nuchal line. At the back of the neck it is
continuous with the deep fascia which gives a thin investment to the trapezius

STERNO-CLEIDO-MASTOID
473
muscle. In front, it is attached to the lower border of the body and great cornu
of the hyoid bone. Below, it ends upon the front surface of the presternum and
the clavicle. The deep layer of the cervical fascia separates from it just below the
hyoid bone, and runs downwards in close proximity to the sterno-hyoid muscles and
the other depressors of the hyoid bone, to the upper part of the posterior surface
of the sternum, and the posterior surface of the clavicle. Laterally, it blends with
and completes the sheath of the sterno-mastoid muscle, which is partly formed by
the superficial layer of the cervical fascia; it also binds down the posterior belly
of the omo-hyoid to the clavicle and first rib. Below its attachment to the sternum
and clavicle it is continued downwards in front of the trachea and great vessels
at the root of the neck into the superior mediastinum, and it finally joins the
pericardium. Behind, it gives an investment to the depressors of the hyoid bone.
Between this deep layer of the cervical fascia and the superficial layer is a small
space containing a part of the course of the anterior jugular vein, a lymphatic
gland, some fat and loose connective tissue.
A still deeper fibrous layer, the prevertebral fascia, stretches across the neck
and divides the cylindrical tube formed by the cervical fascia into a posterior and
anterior compartment. Its surfaces are directed forwards and backwards. Behind,
it rests in the middle line upon the ligaments covering the front of the bodies of
the cervical vertebræ. Laterally, it covers in the prevertebral muscles, and is
attached to the deep surface of the superficial layer of the cervical fascia between
the sterno-mastoid and trapezius muscles.
In the compartment formed between the deep layer of the cervical fascia as it
invests the depressors of the hyoid bone, and the prevertebral fascia, processes are
given off which form the sheath of the great vessels of the neck, and invest the
thyroid gland, the trachea, and pharynx.
The muscles of the front of the neck may be divided into three groups: the
first group consisting of one muscle which ascends from the sternum and clavicle
to the head, the sterno-cleido-mastoideus; the second, of those which ascend from
the sternum, clavicle, and shoulder blade to the hyoid bone and thyroid cartilage;
the third, of those which are attached to the hyoid bone below, and the skull and
lower jaw above.


FIRST GROUP
STERNO-CLEIDO-MASTOID
The sterno-cleido-mastoid, or sterno-mastoid muscle-named from its attach-
ments (kλeís a key, being the equivalent of clavicle)-is a strong ribbon-shaped
band, bifurcated below, and somewhat constricted in its middle third.
Origin. Sternal head: the front of the manubrium (or presternum) between
the notches for the clavicle and first rib, and the middle line. Clavicular head:
The upper part of the anterior surface of the inner third of the clavicle.
Insertion. (1) Along the anterior border and the upper part of the outer
surface of the mastoid process of the temporal bone; (2) the outer half of the
superior nuchal line of the occipital bone.-of
Structure. The sternal head is a rounded but flat tendon; the clavicular is
partly fleshy and partly tendinous. After a course of about an inch, the sternal
head expands into a flat muscle, which conceals the greater part of the clavicular
portion, and, passing upwards, outwards, and backwards, is spread over the whole
line of the upper attachment. Frequently it is so separate from the clavicular
head, that they might very fairly be considered to form two muscles. The clavi-
cular head soon becomes entirely fleshy and ascends more directly. At first it is

474
THE MUSCLES
separated by a small interval from the sternal head, corresponding to a part of the
sterno-clavicular joint, from which it sometimes receives a few fibres of origin;
when they have joined, it passes beneath the sternal head to its insertion, which is
chiefly the lower part of the outer surface of the mastoid process. The whole
insertion in front is composed of short tendinous fibres, and behind of a thin
aponeurosis. As the whole muscle has a very wide range of action, nearly the
whole length of its fibres is fleshy. The sternal head is a little longer than the
other, but has little if any more range of movement. Hence it is tendinous.
Nerve-supply-(1) The spinal accessory nerve, which, while traversing the
deep surface of the muscle at the junction of its upper and middle thirds, sends
FIG. 314.-ANTERIOR AND LATERAL CERVICAL MUSCLES.
Stylo-glossus
Hyo-glossus-
Mylo-hyoid
Anterior belly
of digastric
Raphé of mylo-
hyoid
Thyro-hyoid
Inferior constrictor
Anterior belly of omo--
hyoid
Sterno-hyoid
Sterno-thyroid
Stylo-hyoid
Posterior belly of
digastric
Splenius capitis
Sterno-mastoid
Levator anguli scapulæ
Scalenus medius
Trapezius
Scalenus
posticus
-Posterior belly
of omo-hyoid
filaments to it; (2) the cervical plexus through the anterior primary branches of
the second and third cervical nerves, which enter the upper part of its deep surface.
Action. (1) To flex laterally the head and neck, so as to draw the side of the
head towards the shoulder. (2) To rotate the face towards the opposite side. Of the
two parts of the muscle, the cleido-mastoid portion is more concerned in lateral
flexion, the sterno-mastoid in rotation. The combination of all these movements
may be very well seen in a case of wry-neck, which results from the permanent
contraction of this muscle. (3) When both muscles act, to flex the head and neck
upon the thorax, at the same time raising slightly the chin, which is therefore
carried horizontally forwards. (4) To raise the sternum and inner end of the
clavicle. This action may sometimes be seen in patients with paralysis of all the
parts beneath the cervical region, when the only nerves available for respiratory

STERNO-CLEIDO-MASTOID-STERNO-HYOID
475
movements are the phrenic and those which supply certain of the muscles of the
neck. (5) If the head be much thrown back, the two sterno-mastoids may be used
to increase the extension.
Relations. Superficially, the deep cervical fascia and integuments, the platysma
myoides, external jugular vein, and many of the superficial branches of the
cervical plexus, and the glandulæ concatenatæ; deeply, the rectus capitis anticus
major, omo-hyoid, sterno-hyoid and sterno-thyroid, the posterior belly of the
digastric, the splenius capitis, levator anguli scapulæ, and three scalene muscles;
the common, external, and internal carotid and subclavian arteries, with several
branches of the external carotid, the internal jugular, facial, thyroid, anterior
jugular, and other veins; the spinal accessory and hypoglossal nerves, the cervical
and upper part of the brachial plexuses with many of their branches, the lateral lobe
of the thyroid gland, and numerous deep cervical lymphatic glands.
Variations. The clavicular origin may extend farther outwards upon the collar bone.
Besides its insertion into the mastoid process, this head may have an attachment to the
superior nuchal line, called the cleido-occipital. An extension of the sternal head has
been observed arising from the costal cartilages as low as that of the fifth rib. Slips
sometimes pass from the upper part of the muscle to the angle of the jaw, the pharynx,
the auricle, or the upper attachment of the trapezius.
THE INFRA-HYOID MUSCLES Depnsors of Agrich br
The infra-hyoid muscles form a group of four long flat muscles, arranged in
two layers, and enveloped by the deep layer of the cervical fascia.
SUPERFICIAL LAYER
This consists of two muscles-the sterno-hyoid and omo-hyoid.
1. STERNO-HYOID

The sterno-hyoid (figs. 301, 314)-named from its two attachments-is long and
ribbon-shaped.
Origin. (1) The back of the manubrium (presternum) just internal to the
notches for the clavicle and first rib; (2) the back of the posterior sterno-clavicular
ligament; (3) the back of the inner end of the clavicle external to the facet for
the first costal cartilage.
line.
Insertion. The lower border of the body of the hyoid bone, close to the middle
Structure. It arises fleshy, and forms a band of parallel fibres, which approach
the middle line as they ascend, and are inserted by a short tendon.
Nerve-supply. From the first three cervical nerves through the descendens
and communicans hypoglossi, which send filaments to its deep surface near its
upper end.
Action.-To draw down the body of the hyoid bone, e.g. after it has been raised
in swallowing; also to fix it when the muscles which pass upwards from it are
depressing the tongue, as in suction.
Relations. Superficially, the deep cervical fascia, sterno-mastoid, sterno-
clavicular joint, anterior jugular vein; deeply, the sterno-thyroid, crico-thyroid,
thyroid and cricoid cartilages, the trachea, thyroid isthmus, the anterior jugular
and inferior thyroid veins.

476
AS THE MUSCLES
Variations. The sterno-hyoid may arise from the clavicle alone, and occasionally even
from the middle of that bone. It may be absent or double. A tendinous intersection
sometimes crosses it.
2. OMO-HYOID
The omo-hyoid (pos=shoulder), named from its attachment to the shoulder
blade and the hyoid bone-is ribbon-shaped with a tendinous constriction in the
middle which divides it into two fleshy bellies.
Origin. (1) The upper border of the scapula for about an inch behind the
suprascapular notch; (2) occasionally, the upper border of the transverse ligament
which crosses the notch.
Insertion. The lower border of the body of the hyoid bone just external to
the preceding, which it also slightly overlaps.
Structure. Arising fleshy and broad, the muscle contracts slightly as it passes
forwards, and a little upwards, across the posterior triangle of the neck above the
clavicle. Beneath the sterno-mastoid, and over the great vessels of the neck, it
becomes tendinous for a short distance; and then, changing its direction, it again
expands to a fleshy band which runs upwards and slightly forwards and inwards
to its insertion, which is by short tendinous, intermingled with fleshy, fibres. An
obtuse angle is formed between the two bellies, the lower portion of the muscle
and its tendon being held down by a strong process of the deep layer of the
cervical fascia, which, forming a loop around them, passes downwards to be attached
to the posterior surface of the clavicle and to the first rib.
Nerve-supply. The anterior belly is supplied by a branch from the descendens
hypoglossi, which enters the back of its deep surface, while the posterior receives
a branch from the loop of communication between this nerve and the communi-
cantes hypoglossi which enters the deep surface of the muscle close to its junction
with the tendon.
Action.-(1) To draw down the hyoid bone; (2) very slightly to help in raising
the scapula; (3) to make tense the lower part of the cervical fascia. In this way
it assists the platysma myoides in diminishing the inward suction of the soft
parts, which tends to compress the great vessels and the apices of the lungs during
prolonged inspiratory efforts. The part of the muscle between the sterno-mastoid
and the carotid sheath, being tendinous, will not vary in thickness, otherwise
during contraction it might tend to obstruct the vessels beneath.
Relations. Superficially, the deep cervical fascia, sterno-mastoid, clavicle,
subclavius and trapezius, the external jugular vein, and the descending branches
of the superficial cervical plexus; deeply, the thyro-hyoid, sterno-thyroid, scaleni,
and the first digitation of the serratus magnus, the sheath of the common carotid,
artery and internal jugular vein, the upper part of the brachial plexus, often the
third part of the subclavian artery with the transversalis colli and suprascapular
arteries and the suprascapular nerve.
Variations. These are very frequent. It may be absent or double. The posterior
belly may be attached to the clavicle and scapula, or to the clavicle alone. It may receive
a slip from the manubrium. The anterior belly may blend with the sterno-hyoid, and it
may send a slip to the thyroid cartilage or the mandible.

STERNO-THYROID-THYRO-HYOID
477
SECOND LAYER OF INFRA-HYOID MUSCLES
This consists of two muscles-the sterno-thyroid and thyro-hyoid.
1. STERNO-THYROID
The sterno-thyroid (figs. 301, 314)-named from its attachment to the sternum
and thyroid cartilages-is flat and ribbon-shaped.
Origin. (1) The lower part and side of the back of the manubrium (pre-
sternum), from the middle line to the notch for the first rib cartilage; (2) the back
of the first rib cartilage, and occasionally that of the second; and (3) occasionally
from the back of the clavicle near the facet for the first costal cartilage.
Insertion. The oblique line on the outer surface of the ala of the thyroid
cartilage.
Structure.-Arising fleshy, the two muscles form broad bands of parallel fibres,
which at first lie close to one another, and afterwards diverge slightly as they
ascend. Finally, they are inserted by short tendinous fibres into the thyroid
cartilage. Occasionally the muscle is crossed by a tendinous intersection.
Nerve-supply.-Branches from the loop between the descendens and the com-
municantes hypoglossi which enter the outer part of the deep surface of the muscle.
Action.-(1) To draw down the thyroid cartilage, e.g. after swallowing; (2) in
conjunction with the thyro-hyoid it will depress the hyoid bone.
Relations. Superficially, the cervical fascia and first piece of the sternum,
the anterior jugular vein, the sterno-mastoid and sterno-hyoid and omo-hyoid
muscles; deeply, the thyroid cartilage, inferior constrictor, the cricoid cartilage,
crico-thyroid muscle, thyroid gland, inferior thyroid veins and trachea, the common
carotid artery and left innominate vein.
Variations This muscle may be absent, or double; the muscles of the two sides may
be united. It may send a slip to the carotid sheath.
2. THYRO-HYOID
The thyro-hyoid-named from its attachment to the thyroid cartilage and hyoid
bone-is a quadrilateral sheet.
Origin. The oblique line on the outer surface of the ala of the thyroid cartilage.
Insertion. The lower border of (1) the outer third of the body of the hyoid
bone; and of (2) the inner half of the greater cornu.
-
Structure. This muscle is a continuation upwards of the preceding muscle,
many of its fibres being derived from those of the sterno-thyroid without any
attachment to the cartilage. It consists of parallel fleshy fibres which run nearly
vertically upwards to their insertion into the hyoid bone.
Nerve-supply. A special branch of the hypoglossal nerve which enters the deep
surface of the muscle near its posterior border.
Action. To draw up the thyroid cartilage, as in swallowing, or in the pro-
duction of a high note in singing; (2) in association with the sterno-thyroid to
draw down the hyoid bone.
Relations. Superficially, the sterno-hyoid, omo-hyoid, and sterno-mastoid;
deeply, the thyro-hyoid membrane, the thyro-hyoid bursa and ala of the thyroid
cartilage, the superior laryngeal vessels and nerve.
Variations.-Slips are occasionally seen passing from the cricoid cartilage to the hyoid
bone, or between the upper border of the thyroid cartilage in front and the body of the hyoid
bone.

478
THE MUSCLES
THE SUPRA-HYOID MUSCLES
These consist of four muscles arranged in three layers: the first containing
the digastric and stylo-hyoid, the second the mylo-hyoid, and the third the genio-
hyoid.
1. DIGASTRIC
The digastric-named from its two bellies (yaoTýp the belly)-is composed of
two flattened and somewhat spindle-shaped bellies united by a tendon.
Origin.-(1) Of posterior belly, the digastric fossa of the temporal bone; (2) of
anterior belly, the lower border of the body of the mandible just internal to the
symphysis.
Insertion. By its central tendon, which is attached to the outer part of the
lower border of the body of the hyoid bone and the adjacent part of the great
cornu.
Structure. The posterior belly at its origin consists of short tendinous fibres,
which soon form a laterally compressed muscle. This passes downwards, forwards
and inwards, and converges upon a laterally flattened rounded tendon about half
an inch above the tip of the great cornu of the hyoid bone.
The anterior belly arises by short tendinous fibres, and forms a muscle flattened
from before backwards and from above downwards, which is shorter and smaller
than the posterior belly. Its fibres converge as they pass backwards and slightly
downwards and outwards, to end in the flattened tendon a quarter of an inch
above the junction of the body and great cornu of the hyoid bone. The central
tendon is bound down to its insertion upon the hyoid bone, chiefly by a fibrous
expansion given off from its lower border, and to a very small degree also by the
oblique arch over it formed by the division of the stylo-hyoid muscle. Often a
part of this aponeurosis passes inwards across the middle line and, uniting with its
fellow, forms a membranous covering to the deeper structures, and unites the
inner borders of the two anterior bellies.
Nerve-supply. The posterior belly, which is really a distinct muscle, belonging
to a deeper stratum of the muscular planes, receives a special branch from the
facial nerve which enters the upper part of its deep surface. Perhaps this may be
due to the fact that this part of the muscle assists in swallowing; for the facial
nerve, by means of the Vidian and the relations which through the lesser superficial
petrosal nerve it has with the otic ganglion, may be considered to take part in this
function, as well as in the expression of emotions.
The anterior belly receives at the outer part of its deep surface the terminal
filaments of the mylo-hyoid twig from the inferior dental branch of the inferior
maxillary.
Action.-(1) The posterior belly draws upwards and backwards the hyoid bone,
as in the elevation of the larynx in the second part of deglutition; (2) the anterior
belly, acting from above, draws upwards and forwards the hyoid bone; and, acting
in the opposite direction, (3) it assists in the depression of the lower jaw and in
opening the mouth. Although a comparatively weak muscle, it acts with con-
siderable power in this movement, for it is inserted at the end of the lever of the
second order formed by the mandible, while the resistance which it has to overcome
is exerted by muscles acting much nearer to the fulcrum. Moreover, its direction
downwards and backwards is at a considerable angle with the line of the lever, viz.
that which joins the prominence of the chin to a point a little above the inferior
dental foramen. (4) If the mandible be fixed and both bellies act, the hyoid bone
will be drawn directly upwards. By this action the muscle is of great importance

DIGASTRIC-STYLO-HYOID-MYLO-HYOID
479
in the elevation of the tongue, which rests upon the upper surface of the hyoid
bone. It will therefore help in the first part of deglutition, in which the back of
the tongue is pressed against the hard palate.
Relations. The posterior belly lies beneath the mastoid process, the sterno-
mastoid, splenius, and trachelo-mastoid muscles, the facial vein, and the parotid
gland; in front lies the stylo-hyoid muscle; deeply, the middle constrictor of the
pharynx, the hyo-glossus, the external and internal carotid arteries, and some of
the branches of the external carotid, the internal jugular vein, the hypoglossal and
superior laryngeal nerves.
The tendon lies beneath the deep cervical fascia, platysma myoides, and part of
the stylo-hyoid muscle. Above is the submaxillary gland. On its deep surface is
the rest of the stylo-hyoid muscle, the mylo-hyoid, the hyo-glossus, and the hypo-
glossal nerve.
The anterior belly is covered by the deep cervical fascia and platysma myoides,
and it lies upon the mylo-hyoid muscle.
Variations. A second posterior belly may arise in front of the angle of the mandible;
slips may also arise from the styloid process, or the pharynx. The anterior belly may
be absent; it may be partly or entirely united with that of the opposite side, or may send
a slip to the median raphe of the mylo-hyoid.

2. STYLO-HYOID
The stylo-hyoid-named from its attachments-is a slender fusiform muscle
with a bifurcated lower extremity.
Origin. The back and outer surface of the styloid process of the temporal bone
near its base.
Insertion. The lower border of the body of the hyoid bone at the point of
union with the great cornu.
Structure.-Arising by a short tendon, its fibres soon become fleshy and pass
downwards and forwards. Just before its insertion they divide into two bundles,
which form an obliquely directed arch bridging over the tendon of the digastric
muscle.
Nerve-supply.-A special branch of the facial nerve, which enters its deep
surface from behind.
Action.-The same as that of the posterior belly of the digastric, viz. to draw
the hyoid bone backwards and upwards.
Relations. Superficially, the parotid gland and deep cervical fascia; in front,
the submaxillary gland; behind, the posterior belly of the digastric; deeply, the
middle constrictor and hyo-glossus and the external carotid artery.
Variations.-The stylo-hyoid may arise in part from the cartilage of the external
auditory meatus. It may be absent, or its insertion may be undivided, in which case it
may pass to the inner or outer side of the digastric tendon. A second stylo-hyoid may
run beneath the hyo-glossus to the lesser cornu of the hyoid bone.
3. MYLO-HYOID
The mylo-hyoid-named from its attachment to the lower jaw (uvλn a mill
and the jaw) and to the hyoid bone-is a triangular and somewhat curved sheet.
Origin. The whole length of the mylo-hyoid ridge on the inner surface of the
body of the mandible.
Insertion. (1) The lower edge of the anterior surface of the body of the hyoid
bone; (2) a median raphé extending from the middle of the lower border of the
480
THE MUSCLES
body of the hyoid bone to the back of the symphysis of the mandible immediately
below the genial tubercles.
Structure. Arising by fleshy and short tendinous fibres intermingled, the
muscle passes inwards and slightly downwards to its insertion by short tendinous
fibres into the median raphe and hyoid bone. Sometimes the fleshy fibres are here
and there continuous with those of the other side. Each of them is somewhat
arched, so that the whole sheet has a slight downward convexity. The muscles of
the two sides together form a curved diaphragm which stretches across the angle
contained between the two portions of the mandible.
-
Nerve-supply. From the third division of the fifth cranial nerve, by the mylo-
hyoid branch of the inferior dental which enters the under surface of the muscle by
several filaments.
Action.-(1) To raise the tongue, the floor of the mouth, and the hyoid bone, as
in mastication and the first part of swallowing. By its elevation of the hyoid bone
it will also exert some influence on the larynx and lower part of the pharynx.
These actions will be most efficiently carried out when the jaw is closed. (2)
Acting from below, it will help in the depression of the lower jaw and in opening
the mouth.
Relation. Upon its under surface lie the superficial portion of the submaxillary
gland, the submental artery, and the anterior belly of the digastric muscle. Above,
it is in contact with the genio-hyoid and hyo-glossus, the sublingual gland, the
deep portion of the submaxillary gland, and the hypoglossal nerve.
Variations. The mylo-hyoid may be closely connected with the anterior belly of the
digastric. Openings are sometimes found in the muscular sheet, containing lobules of the
submaxillary gland.
4. GENIO-HYOID
The genio-hyoid-named from its attachment to the chin (yévetov) and the
hyoid bone-is somewhat fusiform, but flattened from above downwards below,
and from side to side above.

Origin. The lower genial tubercle.
Insertion. The upper and anterior surface of the body of the hyoid bone.
Structure. Arising by a short tendon, its fibres pass backwards and slightly
downwards, close to those of the fellow muscle of the other side. Near the hyoid
bone they spread out laterally, and occupy nearly the whole of the upper and
anterior surface of the body, sometimes even a small portion of the greater cornu.
Nerve-supply. The hypoglossal nerve, which sends filaments to the deep
surface.
Action.-(1) To raise and draw forwards the hyoid bone; (2) to draw down the
mandible. In its direction and action it is closely related to the anterior belly of
the digastric.
Relations. Superficially, the mylo-hyoid muscle; deeply, the genio-hyo-
glossus; on its median surface, with its fellow.
Variations. The genio-hyoid may be double, or it may form one muscle with its fellow
of the opposite side.
THE EXTRINSIC MUSCLES OF THE TONGUE
The tongue consists chiefly of muscular tissue, part of which arises from the
adjacent bones, while the rest is made up of bands of fibre which pass longitudinally
or transversely in its substance, and have no external attachment. The latter or

GENIO-HYO-GLOSSUS-HYO-GLOSSUS
481
intrinsic muscles will be described later; the former or extrinsic muscles constitute
a group which is nearly related to those which have been just described. They
consist of four muscles-viz. the genio-hyo-glossus, the hyo-glossus, the stylo-
glossus, and palato-glossus.
1. GENIO-HYO-GLOSSUS
The genio-hyo-glossus-named from its attachment to the chin (yévetov), hyoid
bone, and tongue (yλwooa), is a flat sheet forming the quadrant or, more correctly,
the sector of a circle, and separated from its fellow by a thin stratum of connective
tissue, the septum of the tongue.
Origin. The upper genial tubercle.
Insertion.-(1) The whole length of the tongue in the submucous tissue just
external to the median plane, from the tip along the dorsum to the root of the
tongue; (2) the upper part of the upper and anterior surface of the body of the
hyoid bone; (3) by a few fibres into the side of the pharynx.
Structure. Its origin is by a short tendon, from which its fleshy fibres diverge
in a fan-shaped sheet to their extensive insertion.
Nerve-supply. The hypoglossal, by filaments which enter its outer surface.
Action. (1) To draw downwards and forwards the mesial portion of the tongue
so as to make its dorsum concave upwards in a transverse direction; (2) by its
anterior fibres to draw back the tip of the protruded tongue; (3) by fibres which
pass to the back part of the dorsum of the tongue to draw it forwards, and protrude
the tongue; (4) by its lowest fibres to draw upwards and forwards the hyoid bone,
and so help the genio-hyoid and anterior belly of the digastric in raising the
tongue; (5) acting from below, its hyoid portion will help in depressing the lower
jaw.
Relations.-Externally, the inferior lingualis and hyo-glossus muscles, the
ranine artery, the terminal branches of the hypoglossal and lingual gustatory
nerves, the mucous membrane of the floor of the mouth, the sublingual gland, and
Wharton's duct; internally, the fellow muscle and septum linguæ; along its lower
border, the genio-hyoid muscle.

2. HYO-GLOSSUS
The hyo-glossus-named from its attachments to the hyoid bone and tongue
(ywooa)-is a thin square sheet.
Origin. (1) From the front of the hyoid bone near the upper border of the outer
third of its body; (2) from the upper border of all its great cornu; (3) by a small
slip from the lesser cornu.
Insertion. The submucous tissue and adjacent muscular mass of the posterior
half of the tongue external to the preceding.
Structure. The fleshy fibres arise directly from the bone in a thin sheet, and
ascend nearly parallel to one another. The anterior fibres, however, diverge slightly
forwards, and they all, having reached the upper surface of the sides of the tongue,
bend round inwards, interlacing with the fibres of the palato-glossus and superficial
lingualis to form a submucous cover to the tongue.
Those which arise from the lesser cornu are often described as a distinct
muscle, the chondro-glossus, which is separated from the rest of the muscle by
some bundles which pass from the lower part of the genio-hyo-glossus to the
superior constrictor.
Nerve-supply.-The hypoglossal nerve, which sends filaments into its outer


surface.
II

482
THE MUSCLES
Action. (1) To draw downwards the sides of the tongue, increasing its trans-
verse convexity; (2) to draw backwards the protruded tongue.
Relations. Externally, the mylo-hyoid, digastric, stylo-hyoid, and stylo-
glossus muscles, the lingual vein, lingual gustatory and hypoglossal nerves, the
submaxillary gland and Wharton's duct; deeply, the inferior lingualis, genio-
hyo-glossus, middle constrictor, and part of the origin of the superior constrictor,
the lingual artery, and glosso-pharyngeal nerve.
FIG. 315.-SIDE VIEW OF THE MUSCLES OF THE TONGUE.
Lingualis
inferior
Genio-hyo-.
glossus
Genio-hyoid--
Anterior belly
of digastric
Palato-glossus
Stylo-glossus
Hyo-glossus
Mylo-hyoid
3. STYLO-GLOSSUS
The stylo-glossus-named from its attachments to the styloid process and
tongue (yoooa) is a long, triangular sheet.
Origin. (1) The front of the lower part and tip of the styloid process of the
temporal bone; (2) the upper part of the stylo-maxillary ligament.
Insertion. The submucous tissue and subjacent muscular strata of the side of
the tongue and the adjacent parts of its under surface.
Structure.-Arising by short tendinous fibres, the muscle soon develops into a
long, fan-shaped, laterally-compressed sheet, which passes in a long curve, with an
upward concavity, forwards and slightly downwards and inwards, to the side of the
tongue, where it partly overlaps and partly interlaces with the hyo-glossus muscle,
forming with this muscle and some of the fibres of the palato-glossus a thin
superficial stratum which is continued forwards to the tip of the tongue.
Nerve-supply. From the hypoglossal nerve, by filaments which enter its
external surface.
Action.-(1) To draw back the tongue-for this purpose it arises from the
styloid process as low as possible below the level at which the two other styloid
muscles arise; (2) to draw upwards the sides of the tongue, so as to help the
genio-hyo-glossi and some of the intrinsic muscles in making its upper surface
concave from side to side.


STYLO-GLOSSUS-PALATO-GLOSSUS
483
Relations. Superficially, the internal pterygoid, the parotid gland, lingual
gustatory nerve, and the mucous membrane of the side of the tongue; deeply, the
stylo-pharyngeus, hyo-glossus, inferior lingualis and genio-hyo-glossus, with the
glosso-pharyngeal nerve.
4. PALATO-GLOSSUS

The palato-glossus-named from its attachment to the soft palate and tongue
(yoooa) is a somewhat cylindrical muscle which expands at either end into a
thin sheet.
Origin. The under surface of the aponeurosis of the soft palate; and at
the middle line its fibres are continuous with those of its fellow of the opposite
side.
Insertion. (1) The superficial muscular stratum which covers the side and
adjacent part of the under surface of the tongue; (2) it is partly continuous with
the deep transverse lingualis muscle.
Structure.--Arising in a thin muscular sheet, its fibres form as they pass out-
wards a small cylindrical bundle which, lying in front of the tonsil and against
the wall of the pharynx, constitutes the anterior pillar of the fauces. This bundle
runs downwards and forwards till it reaches the side of the tongue at the junction
of its middle and posterior thirds. Here some of the fibres pass forwards and
downwards to join the superficial stratum formed by the stylo-glossus and hyo-
glossus. The rest pass inwards towards the middle line, being continued into the
deep transverse lingualis muscle. This part of the two muscles, together with
the associated portion of the lingualis transversus, forms a sphincter muscle round
the front part of the faucial opening.
Nerve-supply.-Filaments from the pharyngeal plexus.
Action.-(1) To draw downwards the sides of the soft palate; (2) to draw
upwards and backwards the sides of the tongue. The combination of these two
actions closes the front part of the faucial opening, as in the second part of
swallowing, when the back of the tongue comes into contact with the soft palate,
and prevents the return of the food which is being grasped by the constrictors.
Relations. Superficially, it is covered by the mucous membrane of the soft
palate and the side of the tongue; deeply, it is in contact with the aponeurosis of
the soft palate, the superior constrictor of the pharynx, and the hyo-glossus;
behind it lies the tonsil.
THE DEEP MUSCLES OF THE FRONT OF THE NECK
The deep muscles of the front of the neck consist of an inner and an outer
group, separated from one another by the line of the anterior tubercles of the
cervical vertebræ. Both groups are covered in front by the prevertebral fascia.
OUTER GROUP
The outer group is formed by the three scaleni, which pass from the first two
ribs upwards and inwards to the transverse processes.
[12
484
THE MUSCLES
1. SCALENUS ANTICUS
=
The scalenus anticus-named from its shape (scalenus of unequal sides, being
a term applied to certain triangles in geometry) and its relation to its fellows-is
a thick triangular sheet.
Origin. The scalene tubercle near the inner border of the upper surface of the
first rib.
Insertion. The anterior tubercles of the third, fourth, fifth, and sixth cervical
vertebræ.
Structure.-Arising by a short, somewhat flattened tendon, which is continued
upwards for a short distance upon the front and outer surface of the muscle, the
fleshy fibres diverge as they pass upwards and slightly backwards and inwards to
be inserted by four short tendons into the transverse processes.
Nerve-supply. From the anterior primary branches of the fourth, fifth, and
sixth cervical nerves close to their points of emergence.
Action.-(1) The rib being fixed, it will help to flex, and laterally flex, the neck,
and to rotate it so as to turn the face to the opposite side; (2) it will raise the first
rib, especially in forced inspiration.
Relations. In front lie the sterno-mastoid, omo-hyoid, and subclavius, the
internal jugular vein, the subclavian vein and pneumogastric nerve; on the inner
side are the rectus capitis anticus major, longus colli, and the sympathetic cord;
on the outer side and behind emerge the anterior primary branches of the
cervical nerves separating it from the scalenus medius; and lower down it crosses
in front of the second part of the subclavian artery and the pleura.
2. SCALENUS MEDIUS
The scalenus medius-named from its shape and position-is an elongated
triangular sheet.
Origin. The upper surface of the first rib between the tuberosity and the groove
for the subclavian artery.
Insertion. The front of the posterior tubercles of the six lower cervical vertebræ,
and frequently also the lower part of the lateral mass of the atlas.
Structure.-Arising by a broad band, tendinous in front and muscular behind,
the fleshy fibres form a thick sheet of slightly divergent fibres, which run upwards
and inwards to end upon the vertebræ in six short tendons.
-
Nerve-supply. The posterior primary branches of the cervical nerves as soon
as they emerge supply numerous filaments to the inner part of its anterior surface.
Action.-Acting from below, to flex the neck laterally; acting from above, to
raise the first rib as in forced inspiration, or to fix it in ordinary inspiration.
Relations. In front lie the sterno-mastoid, omo-hyoid, and trapezius, the
subclavian artery, cervical and brachial plexuses; behind, it is in contact with the
levator anguli scapulæ and scalenus posticus.

3. SCALENUS POSTICUS
The scalenus posticus-named from its form and position-is a triangular sheet.
Origin. The upper part of the outer surface of the second rib behind the
rough prominence for the serratus magnus.
-
Insertion. The lower surface of the posterior tubercles of the two or three
lowest cervical vertebræ.

RECTUS CAPITIS ANTICUS MAJOR AND MINOR
485
Structure. Arising partly directly from the bone, and partly by a short apo-
neurosis which covers the outer and posterior part of the origin, its fleshy fibres
converge and are inserted by three short tendons.
Nerve-supply. Small filaments which come from the lower three cervical
nerves at their points of emergence, and, after passing through the scalenus
medius, enter the front surface of the muscle.
Action. When the rib is fixed, to flex the lower part of the neck laterally, and,
acting from above, to raise the second rib, especially in forced inspiration.
Relations. In front lies the scalenus medius; behind, the levator anguli
scapulæ.
Variations of the scaleni. The scalenus posticus may be absent. The scalenus medius
may arise as low as the third rib. A portion of the scalenus anticus may be separate
from the rest, and pass behind the subclavian artery.

INNER GROUP
The inner or prevertebral group consists of the greater and lesser rectus capitis
anticus and the longus colli.
1. RECTUS CAPITIS ANTICUS MAJOR
The rectus capitis anticus major-named from its direction, position, and
size-is a thick, irregular, quadrilateral sheet.
Origin. The front of the anterior tubercles of the third, fourth, fifth, and sixth
cervical vertebræ.
Insertion. A transverse impression upon the under surface of the basilar
process of the occipital bone, extending from just behind the pharyngeal tubercle
outwards and somewhat forwards.
An
Structure. Arising by four tendinous teeth, the parallel fleshy fibres run
upwards and inwards to be inserted directly upon the occipital bone.
incomplete tendinous intersection crosses its anterior surface.
Nerve-supply.-Internal branches from the first and second cervical nerves
enter the upper part of its front surface.
Action.-To flex the head, and slightly to rotate it to the same side.
Relations. In front, the internal and common carotid artery, the internal
jugular vein, the pneumogastric and sympathetic nerves, and the upper part of
the pharynx; behind, the rectus capitis anticus minor, and part of the longus

colli.
2. RECTUS CAPITIS ANTICUS MINOR
The rectus capitis anticus minor-named from its direction, position, and size
-is thick and ribbon-shaped, and continues the series of the anterior intertrans-
versales.
Origin.--The upper surface of the lateral mass of the atlas in front of the
articular process.
Insertion. The under surface of the basilar portion of the occipital bone in
front of the foramen magnum, but not as far inwards as the preceding muscle.
Structure. Parallel or slightly divergent fleshy fibres which run upwards and
inwards.
Nerve-supply. The first cervical nerve, which sends a filament to its front
surface.
Action. To flex the head.

486
THE MUSCLES
Relations. In front, the rectus capitis anticus major; behind, the anterior
occipito-axial ligament.
3. LONGUS COLLI
The longus colli-named from its length and the region in which it lies-is a
compound muscle, and forms an elongated triangular sheet with the base running
vertically along the outer border of the anterior common ligament, and the obtuse
apex directed outwards. It consists of three portions: one mesial, the vertical;
and two lateral, the upper and lower oblique portions.
FIG. 316. THE MUSCLES OF THE FRONT OF THE NECK.
Rectus capitis
anticus minor
Rectus capitis
lateralis
Rectus capitis.
anticus major
Rectus capitis
lateralis
Rectus capitis
anticus minor
Intertransversalis
anterior
-Intertransversalis
posterior
Origin of rectus.
capitis anticus
major
Longus colli
Scalenus medius-
Insertion of
scalenus anticus
Scalenus anticus
Scalenus medius
Scalenus posticus-
-Scalenus posticus
Vertical portion:-
Origin. Lateral part of front of bodies of last two cervical and first three
thoracic vertebræ, external to the anterior common ligament.
Insertion. Lateral part of front of bodies of second, third, and fourth cervical
vertebræ.
Lower oblique portion:-
Origin. The side of the front of the bodies of the first three thoracic vertebræ.

ABNORMAL MUSCLES
487
Insertion.
The front of the anterior tubercles of the transverse processes of
the fifth and sixth cervical vertebræ.
Upper oblique portion :-
Origin. The front of the anterior tubercles of the transverse processes of the
third, fourth, and fifth cervical vertebræ.
Insertion. The under surface and front of one side of the anterior tubercle
of atlas.
Structure. All three portions arise by short tendons, then become fleshy, and
are inserted by short tendons, with the exception of the superior oblique portion,
which has a fleshy attachment to the tubercle of the atlas.
Nerve-supply. The anterior branches from the cervical nerves soon after their
emergence.
-
Action. To flex the neck; and also by its oblique portions slightly to rotate
and laterally flex it.
Relations. In front, the pharynx, oesophagus, great vessels of the neck, the
inferior thyroid artery, the sympathetic cord, the pneumogastric nerve, and the
recurrent laryngeal nerve; behind, the vertebral column, and, under cover of
the lower oblique portion, the vertebral artery.
ABNORMAL MUSCLES
By J. BLAND SUTTON, F.R.C.S.
ASSISTANT SURGEON TO AND LECTURER ON MORPHOLOGY AND COMPARATIVE ANATOMY
AT THE MIDDLESEX HOSPITAL.
The abductor ossis metatarsi quinti arises from the outer tubercle of the calcaneum.
It is inserted into the tuberosity at the base of the fifth metatarsal bone. The origin
and insertion are marked in fig. 169. It is present in two out of every three subjects, and
when not represented by muscle fibres its place is occupied by a band of fibrous tissue.
The anomalus arises from the nasal process of the maxilla beneath the levator labii
superioris alaque nasi. It is inserted into the maxilla close to the origin of the com-
pessor naris.
Azygos pharyngis.-This muscle arises from the pharyngeal tubercle on the under
surface of the body of the occipital bone.
It is inserted into the raphe of the pharynx superficial to the insertion of the superior
and middle constrictor muscles. It may blend with the ascending fibres of the middle
constrictor. It is often represented by a fibrous band. [For figure, see Macalister, Proc.
Royal Irish Academy, vol. ix.]
The cleido-occipitalis arises from the clavicle posterior to the sterno-mastoid. It runs
upwards parallel with the posterior border of the sterno-mastoid to be inserted into the
superior nuchal line of the occipital bone anterior to the origin of the trapezius. [Perrin;
a good figure in Journ. of Anat. and Phys. vol. v. p. 253.]
The cleido-hyoid arises from the clavicle near the outer border of the sterno-hyoid.
It is inserted into the body of the hyoid superficial to the sterno-hyoid.
The costo-fascialis is a muscular slip given off from the outer border of the sterno-
thyroid near its origin.
It is inserted into the sheath of the carotid vessels, and sometimes reaches as high
as the level of the thyroid cartilage.
The chondro-epitrochlearis arises from the cartilages of one or two ribs (usually the
seventh), or from the aponeurosis of the external oblique muscle.
It is inserted into the fascia on the inner side of the arm, or into the intermuscular
septum, and sometimes into the internal condyle of the humerus. [For figure, see Perrin,
Journ. of Anat. and Phys. vol. v. plate ix.]
The curvator coccygis arises from the anterior surface of the fifth piece of the sacrum.
It is inserted into the anterior surface of the coccyx. [For figure, see M. Watson,
Journ. of Anat. and Phys. vol. xiv. p. 407.]
488
THE MUSCLES
The depressor thyroidea arises from the lower border of the first ring of the trachea
quite close to the middle line.
It passes vertically upwards to be inserted into the lower border of the thyroid carti-
lage internal to the crico-thyroid. [The muscle is figured by Messenger Bradley in
Journ. of Anat. and Phys. vol. vi. p. 420.]
The dorso-epitrochlearis is a muscular slip given off by the tendon of the latissimus dorsi
at the axilla. Sometimes it is directly continuous with a chondro-epitrochlearis muscle.
It is inserted into the long head of the triceps, or into the fascia of the arm, and some-
times into the internal intermuscular septum. [For figure, see Perrin, Journ. of Anat.
and Phys. vol. v. plate x.]
The extensor primi internodii hallucis longus is usually an offset from the extensor pro-
prius, but it may arise separately from the fibula and interosseous membrane.
It is inserted into the inner part of the base of the first phalanx of the hallux. [See
Wood, Proc. Roy. Soc. vol. xv. p. 535.]
The extensor ossis metatarsi hallucis arises as a slip from the extensor proprius hallucis
or from the extensor communis digitorum, or from the tibialis anticus. It may arise as a
separate muscle close to the extensor proprius.
It is inserted into the metatarsal bone of the hallux.
The extensor coccygis arises from the posterior surface of the last piece of the sacrum.
It is inserted into the posterior surface of the coccyx.
The extensor carpi radialis accessorius arises from the humerus below the extensor
carpi radialis longior.
It is inserted into the metacarpal bone of the thumb, or into the abductor pollicis, or
into the first dorsal interosseous muscle.
The extensor annularis arises from the posterior surface of the ulnar shaft below the
extensor indicis. When an extensor medius is also present, it will arise in common with
the annularis.
The tendon passes under the annular ligament with the common extensor, and is
inserted into the tendon of the ring (fourth) finger.
The extensor brevis digitorum manus arises from the ligamentous tissues on the back
of the carpus. It passes under the posterior annular ligament, and gives off three slips
which blend with the tendons of the third, fourth, and fifth digits.
The epitrochleo-anconeus is a small muscle arising from the back of the internal
condyle of the humerus, and passing over the ulnar nerve is inserted into the inner side
of the olecranon.

6
This is the most frequent of all the muscles to which the term abnormal' is applied.
[For figure, see Wood, Proc. Roy. Soc. vol. xv. p. 521.]
The extensor medii digiti arises from the posterior surface of the shaft of the ulna
immediately below the extensor indicis.
Its tendon passes under the annular ligament in the same compartment as the common
extensor, and is inserted into the tendon of that muscle which goes to the middle finger.
Sometimes a tendon for the middle finger is given off by the extensor indicis.
The flexor accessorius longus arises from the fascia over the flexor longus hallucis; it
passes with the tendon of this muscle beneath the internal annular ligament; and ends
in a tendon which crosses the long plantar ligament obliquely, to be inserted into the
sesamoid bone in the tendon of the peroneus longus.
When this muscle is present, the accessorius is sometimes absent. [For figure, see
Thane, Proc. Anat. Soc. of Gt. Britain and Ireland, May 1891.]
The flexor carpi radialis brevis vel profundus arises from the front surface of the radius
near the anterior border, above the pronator quadratus, but below the flexor longus
pollicis.
The insertion is very variable: in some cases it only reaches the annular ligament,
whilst in others it passes under this structure to be inserted into the trapezium, magnum,
or the base of the second or third metacarpal bones. [For figure, see Wood, Journ. of
Anat. and Phys. vol. i. p. 57.]
The gluteus quartus arises from the anterior part of the inferior gluteal ridge of the
ilium; it lies in close contact with the capsular ligament of the hip joint.
It is inserted into the top of the great trochanter of the femur anterior to the insertion
of the gluteus minimus. [For good figure, see Gruber, Virchow Arch. bd. evii. s. 480.]
Hyo-epiglottideus.-This muscle arises from the middle of the ridge on the lingual
aspect of the epiglottis.
It is inserted into the median tubercle on the body of the hyoid bone. It is often
represented by a fibrous band. [See Journ. of Anat. and Phys. vol. xxiii. p. 256.]
The iliacus minor, or ilio-capsularis, arises from the anterior inferior spine of the ilium.
It is inserted into the lower part of the anterior intertrochanteric line, or into the ilio-
femoral portion of the capsule.
The interclavicular muscle usually consists of two fleshy bellies with a stout inter-


ABNORMAL MUSCLES
489
mediate tendon. It arises from the clavicle, anterior to the attachment of the rhomboid
ligament and from the ligament itself.
It is inserted into a corresponding position on the opposite clavicle, and fills up the gap
between the sternal ends of the clavicles. [Lane, Journ. of Anat. and Phys. vol. xx. p. 544.]
The interosseus primus volaris is a slender muscle arising from the ulnar side of the
base of the first metacarpal bone.
It is inserted into the side of the base of the first phalanx of the thumb in common
with the adductor pollicis.
Its origin and insertion are marked in fig. 138, p. 139.
Kerato-thyroid.--A short, slender muscle arising from the lower border of the cricoid
cartilage behind the articular facet.
It is inserted into the inferior cornu of the thyroid cartilage.
Levator glandulae thyroidea. This muscle arises from the isthmus, but more frequently
from the pyramidal process of the thyroid body.
It is inserted into the anterior surface of the body of the hyoid bone. Frequently it
is connected with the thyro-hyoid muscle, and occasionally with the sterno-thyroid.
The levator claviculæ arises from the transverse processes of the first and second
cervical vertebra; it appears as a dismemberment of the levator anguli scapula.
It is inserted into the outer half of the clavicle.
The mylo-glossus, a small accessory slip of the stylo-glossus, arises from the angle of
the mandible, or from the stylo-maxillary ligament.
It is inserted into the side of the tongue between the stylo- and hyo-glossus muscles.
[For figure, see Wood, Proc. Roy. Soc. vol. xv. p. 523.]
The mento-hyoideus is a slip of muscle which arises from the body of the hyoid bone.
Sometimes it consists of two parallel slips.
It is inserted into the symphysis superficial to the mylo-hyoid muscle.
The occipito-hyoid arises from the mastoid process of the temporal bone and adjacent
portion of the superior nuchal line. It passes superficially across the sterno-mastoid near
its origin, to be inserted into the hyoid bone near the junction of the cornua with the
basi-hyoid, and in close association with the posterior belly of the digastric. [Perrin:
good figures in Journ. of Anat. and Phys. vol. v. pp. 251-3.]
The peroneo-calcaneus internus arises from the lower part of the flexor (posterior)
surface of the fibula, external to the origin of the flexor longus hallucis. Its tendon
passes beneath the internal annular ligament with the tendon of the flexor longus hallucis,
to be inserted into the fore part of the inner surface of the calcaneum. [For figure and
reference, see Thane, Proc. Anat. Soc. of Gt. Britain and Ireland, May 1891.]
The pterygoideus proprius arises from the crest on the greater wing of the sphenoid.
It is inserted into the posterior border of the external pterygoid plate, and occasion-
ally into the tuberosity of the maxilla. [For figure, see Wagstaffe, Journ. of Anat.
and Phys. vol. v. p. 282.]
The pterygo-spinous arises from the alar spine of the sphenoid.
It is inserted into the posterior margin of the external pterygoid plate. This muscle
is sometimes replaced by ligament.
The peroneus quinti digiti arises from the lower fourth of the fibula under cover of the
peroneus brevis.
It is inserted into the aponeurosis on the extensor surface of the little toe. [Wenzel
Gruber has devoted a monograph to this muscle, entitled Musculus Peronei Digiti V.
Berlin, 1886.]
The peroneus quartus arises from the flexor surface of the fibula between the peroneus
brevis and flexor longus hallucis.
It is inserted into the ridge of the cuboid, or into the peroneal tubercle of the




calcaneum.
The popliteus minor arises from the femur to the inner side of the plantaris.
It is inserted into the posterior ligament of the knee joint.
The peroneo-tibialis arises from the inner side of the head of the fibula.
It is inserted into the upper extremity of the oblique line of the tibia beneath the
popliteus.
The psoas parvus arises from the bodies of the last thoracic and first lumbar vertebræ
and from the disc between them.
It is inserted by means of a thin flat tendon into the ilio-pectineal line. This muscle
is frequently present.
The rotator humeri arises from the under surface and outer border of the coracoid
process of the scapula.
It passes across the tendon of the subscapularis, to be inserted into the neck of the
humerus, below the lesser tuberosity, and between the insertions of the subscapularis
and the conjoined tendons of the latissimus dorsi and teres major muscles.
The rotator humeri is a part of the coraco-brachialis muscle, and is often referred to

490
THE MUSCLES
as the coraco-brachialis superior vel brevis. [For figure, see Wood, Journ. of Anat. and
Phys. vol. i. p. 47.] The insertion of this muscle is indicated in fig. 128.
The rhombo-atloideus arises from the sixth and seventh cervical and first thoracic
spinous processes, superficial to the serratus posticus superior.
It is inserted into the transverse process of the atlas. [See Macalister, Proc. Roy. Irish
Academy, vol. ix. plate v.]
The rectus capitis anticus medius arises from the middle of the anterior surface of the
body of the axis near its lower border by means of a tendon. As it passes vertically
upwards, it bifurcates, each fleshy belly being inserted into the basilar process of the
occipital bone immediately in front of the foramen magnum, posterior to the insertion
of the rectus capitis anticus major, and internal to that of the rectus capitis anticus
minor. [Walsham, Journ. of Anat. and Phys. vol. xviii. p. 461.]
The supraclavicularis arises by a slender tendon from the upper border of the manu-
brium of the sternum. It passes outwards, above the sterno-clavicular joint, behind the
sterno-mastoid muscle, to be inserted into the clavicle. When present in both sides, the
muscle sometimes fuses in the middle line.
The sternalis muscle (rectus sternalis) arises from the sheath of the rectus abdominis,
or from the tissues covering the fifth and sixth costal cartilages.
The direction of the fibres is very variable. In some cases they are directed
obliquely outwards; in others, they pass vertically upwards to be inserted into the fascia
covering the origin of the sterno-mastoid, or into the aponeurosis of the pectoralis major,
or into the upper part of the manubrium of the sternum. A sternalis may be present on
each side. In some instances they are entirely muscular; in others, furnished with
terminal tendons. [See Journ. of Anat. and Phys. vols. i. p. 246, xviii. p. 208, xix.
p. 311.]
The tibio-fascialis anticus arises from the lower third of the anterior border of the
tibia.
It is inserted into the annular ligament and deep fascia.
The transversus nucha is a muscular fasciculus arising from the external occipital
protuberance superficial to the trapezius.
It is inserted into the aponeurosis of the sterno-mastoid.
The triticeo-glossus arises from the cartilago triticea in the thyro-hyoid ligament.
It is inserted into the side of the tongue, blending with the posterior fibres of the
hyo-glossus.
The occipito-scapular arises from the occipital bone on a level with the splenius capitis
under cover of the trapezius. It passes downwards to be inserted into the posterior
border of the scapula at the base of the spine. [For figure, see Wood, Proc. Roy. Soc.
vol. xv. p. 521.]

SECTION IV
ARTERIES, VEINS, AND
LYMPHATICS
By W. J. WALSHAM, F.R.C.S.
SENIOR ASSISTANT SURGEON TO ST. BARTHOLOMEW'S HOSPITAL; LECTURER ON ADVANCED ANATOMY IN
ST. BARTHOLOMEW'S HOSPITAL MEDICAL SCHOOL, ETC., ETC.
THE ARTERIES
HE arteries are divided into the pulmonary and the systemic. The pulmonary
THERE
convey the blood from the right ventricle of the heart to the lungs, whence
it is returned, when aërated, by the pulmonary veins to the left auricle, and through
that cavity into the left ventricle. The systemic arteries carry the blood from the
left ventricle all over the body, whence it is returned by the veins to the right
auricle, and through it to the right ventricle. The lungs also receive blood from the
systemic arteries-the bronchial. This blood which serves for the nourishment of
the larger and smaller branches of the bronchial tubes and the lung substance is
returned, in part by the bronchial veins to the general venous circulation, and thence
to the right side of the heart; and in part by the pulmonary veins, along with the
aërated blood, to the left side of the heart.


THE PULMONARY ARTERY
The pulmonary artery (fig. 317) passes from the right ventricle to the lungs.
It differs from all other arteries in the body in that it contains venous blood. It
arises as a short, thick trunk from the upper and front part of the right ventricle
known as the conus arteriosus, and, after a course of about two inches within the
pericardium-the serous layer of which membrane forms a common sheath for it
and the aorta-divides into a right and left branch, which pierce the pericardium,
and pass to the right and left lung respectively.
The trunk of the pulmonary artery at its origin (fig. 319) is on a plane
anterior to the first portion of the arch of the aorta, and slightly overlaps that vessel.
Thence it passes upwards, backwards, and to the left, forming a slight curve round
the front and left side of the ascending portion of the aorta (fig. 321); and, having
reached the concavity of the transverse portion of the aortic arch, on a level with the
fifth thoracic vertebra, and on a plane posterior to the ascending aorta, it divides into
its right and left branches, which diverge from each other at an angle of about 130°.
In the foetus, the pulmonary artery (fig. 318) continues its course upwards, back-
wards, and to the left, under the name of the ductus arteriosus, or ductus Botalli,

492
THE ARTERIES
and opens into the descending aorta just below the origin of the left subclavian
artery. After birth, that portion of the pulmonary artery which extends to the
aorta becomes obliterated, and remains merely as a fibrous cord.
The trunk of the artery with the ductus Botalli was originally the left fifth aortic
arch, and the recurrent laryngeal nerve in early foetal life passed below it direct to
the larynx. As in the process of development the heart descends into the thorax,
and the fifth arch assumes a more vertical direction, it comes to pass that the
nerve winds round the transverse portion of the aorta, the fourth aortic arch, and
consequently external to the ductus arteriosus (fig. 321). In adult life the cord formed
FIG. 317.-ANTERIOR VIEW OF THE HEART WITH THE LARGE ARTERIES AND VEINS.
(By permission. Royal College of Surgeons Museum.)
Right superior thyroid vein
Right common carotid artery
Internal jugular vein
Vertebral vein
Left common
carotid artery Internal jugular vein
Left superior
thyroid vein
THYROID
BODY
Left vertebral vein
External jugular vein
-Left subclavian vein
Left innominate vein
Subclavian vein
Inferior thyroid veins
Vena azygos major
Vena cava superior-
Aorta
Left superior intercostal
vein
DUCTUS ARTERIOSUS
Left pulmonary artery
and vein
LEFT AURICULAR APPENDIX
Right pulmonary-
artery
PERICARDIUM-
RIGHT AURICLE
RIGHT VENTRICLE-
Vena cava inferior-
Pulmonary artery
LEFT VENTRICLE
Aorta
by the obliterated ductus arteriosus arises a little to the left of the bifurcation of the
pulmonary artery, and receives a slight reflexion from the pericardium as it pierces
that membrane. It occasionally remains partially unobliterated.
Relations. In front, the trunk of the pulmonary artery is covered by the first.
bone of the sternum, the remains of the thymus gland, and the pericardium (fig.319).
Behind, it lies successively upon the ascending part of the arch of the aorta and
the left auricle.
To the right are the ascending aorta, the right auricular appendix, the right
coronary artery, and the cardiac nerves.
To the left are the pericardium,
the left pleura and lung, the left auricular
appendix, the left coronary artery, and the cardiac nerves.

THE PULMONARY
493
FIG. 318.-THE HEART, WITH THE ARCH OF THE AORTA, THE PULMONARY ARTERY, THE
DUCTUS ARTERIOSUS, AND THE VESSELS CONCERNED IN THE FETAL CIRCULATION.
(From a preparation of a foetus in the Museum of St. Bartholomew's Hospital.)
Right innominate
vein
Vena cava superior
Right pulmonary
artery
Vena cava inferior
Left innominate
vein
Arch of aorta
DUCTUS ARTERIOSUS
Left pulmonary
artery
Left branch of
portal vein
DUCTUS VENOSUS
Descending aorta
Umbilical vein.
Portal vein
Right branch of
portal vein
Umbilical vein
Umbilical arteries
Hypogastric artery
LADDER
PLACENTA
Superior
mesenteric artery
Splenic vein
Superior
mesenteric vein
Inferior
mesenteric artery
Left common iliac
artery
Internal iliac
artery
External iliac
artery
THE RIGHT PULMONARY ARTERY
The right pulmonary artery (figs. 319, 320), longer than the left, passes almost
horizontally outwards under the arch of the aorta to the root of the right lung, where
it divides into a larger upper branch, which supplies the upper lobe and gives off a
descending branch to the middle or third lobe, and into a smaller inferior branch for

494
THE ARTERIES
FIG. 319.-DIAGRAM OF THE RELATIONS OF THE PULMONARY ARTERY
AND ITS RIGHT AND LEFT BRANCHES.
PNEUMOGASTRIC
NERVE
Vena azygos major
RIGHT BRONCHUS
Right pulmonary artery
RIGHT PHRENIC
NERVE
Vena cava superior.
PERICARDIUM
RIGHT AURICULAR APPENDIX
Right coronary artery
RIGHT PLEURA AND LUNG
4TH
THORACIC
VERTEBRA
Aorta
THORACIC DUCT
CESOPHAGUS
PNEUMOGASTRIC NERVE
LEFT BRONCHUS
Left pulmonary artery
AORTA
LEFT PHRENIC NERVE
Pulmonary artery
PERICARDIUM
LEFT PLEURA AND LUNG
FIRST BONE OF STERNUM
FIG. 320.-POSTERIOR VIEW OF HEART AND GREATER VESSELS.
(By permission. Royal College of Surgeons Museum.)
Left common carotid artery Superior thyroid
Left vertebral vein
Left
internal
jugular vein
vein
THYROID BODY
Right common carotid artery
Right internal jugular vein
External jugular vein
External jugular vein
Ascending cervical
artery
Inferior thyroid
artery
Left subclavian vein
Left subclavian artery-
Internal mammary-
artery
Left common carotid
artery
Aorta
Left superior
intercostal vein
Ductus arteriosus-
Pulmonary arteries
Pulmonary veins
LEFT AURICULAR
APPENDIX
Right subclavian
artery
Right subclavian vein
Right innominate
vein
Innominate artery
Vena azygos major
Vena cava superior
PERICARDIUM
Pulmonary arteries
-Pulmonary arteries
Aorta
-Vena cava inferior

LEFT PULMONARY-THE AORTA
495
the supply of the inferior lobe. These branches follow the course of the bronchi,
dividing and subdividing for the supply of the lobules of the lung. The terminal
branches do not anastomose with each other.
Relations. In its course to the lung it has in front of it (fig. 319) the ascending
aorta, the vena cava superior, the phrenic nerve, the anterior pulmonary plexus, and
the reflexion of the pleura. Behind is the right, bronchus. Above is the trans-
verse portion of the arch of the aorta, and below is the left auricle.
At the root of the lung it has the right bronchus above and behind it; the
pulmonary veins below and in front. Crossing in front of it and the other struc-
ture forming the root of the lung are the phrenic nerve and the anterior pulmonary
plexus; behind are the vena azygos major, the pneumogastric nerve, and the
posterior pulmonary plexus (fig. 324).
THE LEFT PULMONARY ARTERY
The left pulmonary artery, shorter and slightly smaller than the right, passes
in front of the descending aorta to the root of the left lung, where it divides into
two branches for the supply of the upper and lower lobes respectively. These
divide and subdivide as on the right side (fig. 319).
Relations. At the root of the lung it has the left bronchus behind and also
below it in consequence of the more vertical direction taken by the left bronchus
than by the right. Below and in front are the pulmonary veins. Crossing in front
of it and the other structures forming the root of the lung are the phrenic nerve,
the anterior pulmonary plexus, and the reflexion of the left pleura; crossing
behind, are the descending aorta, the left pneumogastric nerve, and the posterior
pulmonary plexus (fig. 324).
THE SYSTEMIC ARTERIES
THE AORTA

The aorta is the main systemic arterial trunk, and from it all the systemic
arteries are derived. It begins at the left ventricle of the heart, and, after running
a short distance upwards and to the right, turns backwards and to the left, and then
downwards, forming the arch of the aorta. It is thence continued through the
thorax as the thoracic aorta, and finally enters the abdomen at the aortic opening
in the diaphragm, and, passing through the abdominal cavity under the name of
the abdominal aorta, terminates opposite the fourth lumbar vertebra in the right
and left common iliac arteries. From the point of bifurcation a small vessel is
continued down the middle line in front of the sacrum and coccyx, and ends in the
coccygeal glomerulus. This vessel (known as the middle sacral) is usually regarded,
morphologically, as the sacral and coccygeal aorta; while the coccygeal glomerulus
is believed to represent the rudiments of the caudal aorta, with probably a persistent
part of the post-anal gut.
THE ARCH OF THE AORTA
The arch of the aorta (fig. 321) begins at the upper and back part of the left
ventricle of the heart, behind the sternum, on a level with the lower border of the

496
THE ARTERIES
third left costal cartilage. Thence it passes upwards and slightly forwards and to
the right, as high as the level of the upper border of the second costal cartilage of the
right side; and then, curving backwards, upwards, and to the left, crosses behind the
sternum at the level of the middle of the manubrium; and, reaching the left side of
the body of the fourth thoracic vertebra, runs downwards on the side of the body of
that and the fifth thoracic vertebra, at the lower border of which it terminates in the
FIG. 321.-THE ARCH OF THE AORTA, WITH THE PULMONARY ARTERY AND
CHIEF BRANCHES OF THE AORTA.
(From a dissection in St. Bartholomew's Hospital Museum.)
RIGHT RECURRENT
LARYNGEAL NERVE
Transverse cervical artery
Right common carotid
artery
Suprascapular artery
Internal jugular vein
PNEUMOGASTRIC
NERVE
Subclavian vein
Inferior thyroid vein
PHRENIC NERVE
Left innominate vein
Ascending aorta
Superior vena cava
RIGHT BRONCHUS
Branch to superior
lobe of lung
Upper branch of right
pulmonary artery
Branch to middle lobe
of lung
Right pulmonary vein
RIGHT AURICLE
Right coronary artery
THORACIC VERTEBRA
Intercostal vein
Intercostal artery
Vena azygos major
Intercostal vein
Intercostal artery
Intercostal vein
Intercostal artery
THYROID BODY
LEFT RECURRENT
LARYNGEAL
NERVE
PNEUMOGASTRIC
NERVE
Left internal jugular
vein
Left common carotid
artery
Left subclavian artery
Left subclavian vein
TRACHEA
Inferior thyroid vein
PHRENIC NERVE
(hooked aside)
RECURRENT
LARYNGEAL
NERVE
PNEUMOGASTRIC
NERVE
DUCTUS ARTERIOSUS
Left pulmonary
artery
Pulmonary artery
Right pulmonary
artery
LEFT BRONCHUS
Left coronary artery
Left pulmonary vein
RIGHT VENTRICLE
(Conus arteriosus)
CESOPHAGUS
(hooked aside)
THORACIC DUCT
Thoracic aorta
thoracic aorta. The arch thus formed has its convexity upwards and to the right;
in its concavity are situated the left bronchus and the right pulmonary artery.
According to its direction, it is somewhat arbitrarily divided into an ascending,
transverse, and descending part. Morphologically, the ascending portion is the
ventral aorta; the descending portion, part of the left dorsal aorta; and the transverse
portion, the fourth left aortic arch. Each portion requires a separate description.

THE ARCH OF THE AORTA
497
THE ASCENDING PORTION OF THE ARCH OF THE AORTA
The ascending portion or ventral aorta ascends behind the sternum from the
upper part of the left ventricle of the heart, on a level with the lower border of the
third left costal cartilage, to the upper border of the second right costal cartilage.
It measures from two to two and a quarter inches (5.5 cm.), forming, as it ascends, a
gentle curve, the most prominent part of which, when the aorta is distended, is
situated about a quarter of an inch (6 mm.) from the sternum. It is enclosed for
the greater part of its length in the pericardium, being invested, together with
the pulmonary artery, in a common sheath formed by the serous layer of that
membrane. A dilatation known as the great sinus of the arch of the aorta is
often present along the right side. Immediately above the heart the aorta presents
three bulgings, known as the sinuses of Valsalva; they are placed, two anteriorly,
and one posteriorly. From the anterior are derived the coronary arteries of the
heart. (See HEART.)
Relations. In front (fig. 322), it is overlapped at its commencement by the
right auricular appendix and the pulmonary artery. Higher up, as the pulmonary
FIG. 322. SCHEME OF THE RELATIONS OF THE FIRST PORTION OF THE ARCH OF
THE AORTA.
I, at origin; II, a little higher up.
PERICARDIUM
I
RIGHT AURICLE
AORTA
RIGHT AURICULAR APPENDIX
RIGHT BRONCHUS
Right pulmonary artery
II
Vena cava superior
AORTA
PERICARDIUM
PLEURA
LUNG
LEFT AURICLE
Pulmonary artery
Left pulmonary artery
Pulmonary artery
PERICARDIUM
LUNG
PLEURA
REMAINS OF THYMUS GLAND
MANUBRIUM
artery and auricular appendix diverge, it is separated from the manubrium by the
pericardium, the remains of the thymus gland, and by the loose tissue and fat in
the superior mediastinum, and is here slightly overlapped by the right pleura and
by the edge of the right lung in full inspiration.
Behind are the left auricle of the heart, the right pulmonary artery, the right
bronchus, and the anterior right deep cardiac nerves.
KK

498
THE ARTERIES
On the right side it is in contact, below with the right auricle, and above with
the superior vena cava.
On the left side are the pulmonary artery and the branches of the right super-
ficial cardiac nerves.
THE TRANSVERSE PORTION OF THE ARCH OF THE AORTA
The transverse portion of the arch of the aorta extends in a gentle curve
upwards, backwards, and to the left, from the level of the upper border of the
second left costal cartilage to the left side of the body of the fourth thoracic
vertebra. Passing under the arch are the left bronchus, the right pulmonary
artery, and the left recurrent laryngeal nerve. It measures about one inch and
four-fifths (4.5 cm.).
FIG. 323.-SCHEME OF THE RELATIONS OF THE TRANSVERSE PORTION OF THE
ARCH OF THE AORTA.
CESOPHAGUS
TRACHEA
Left carotid
artery
Innominate
artery
RIGHT PLEURA
RIGHT LUNG
3RD THORACIC
VERTEBRA
THORACIC DUCT
RECURRENT LARYNGEAL NERVE
-Left subclavian artery
Left superior intercostal vein
PNEUMOGASTRIC NERVE
CARDIAC BRANCHES OF SYMPATHETIC
CARDIAC BRANCHES OF PNEUMOGASTRIC
-PHRENIC NERVE
LEFT LUNG
LEFT PLEURA
Relations. In front (fig. 323), it is slightly overlapped by the right pleura and
lung, and to a greater extent by the left pleura and lung. It is crossed in the
following order from right to left, by the phrenic nerve, by the cardiac branches of
the pneumogastric nerve, the cardiac branches of the sympathetic nerve, by the
pneumogastric nerve, and by the left superior intercostal vein as it passes up to the
left innominate vein.
Behind it (fig. 823), are the trachea, the esophagus, the thoracic duct, the deep
cardiac plexus which is situated on the trachea just above its bifurcation, and the
left recurrent laryngeal nerve.
Above it (fig. 321) are the three chief branches for the head, neck, and upper
extremities, namely, the innominate, the left carotid and the left subclavian
arteries, and the left innominate vein.
Below it-that is, in its concavity-are the bifurcation of the pulmonary artery,
the left bronchus, the left recurrent laryngeal nerve, the remains of the ductus
arteriosus, the superficial cardiac plexus, and two or more bronchial lymphatic
glands (fig. 321).

THE ARCH OF THE AORTA
499
THE DESCENDING PORTION OF THE ARCH OF THE AORTA
The descending portion of the arch of the aorta, morphologically a part of
the primitive dorsal aorta, descends by the left side of the body of the fourth and
fifth thoracic vertebræ, and ends at the lower border of the latter in the thoracic
aorta.
Just below the spot where the ductus arteriosus (the fifth left arch) joins the
aorta, a constriction (the aortic isthmus) is at times met with, and below this
again a dilatation of a fusiform shape (the aortic spindle).
FIG. 324. THE HEART AND GREAT VESSELS, WITH THE ROOT OF THE LUNGS,
SEEN FROM BEHIND. (St. Bartholomew's Hospital Museum.)
CESOPHAGUS
TRACHEA
THORACIC DUCT-
Left subclavian artery-
LEFT PNEUMO-
GASTRIC NERVE
LEFT RECURRENT
LARYNGEAL NERVE
Intercostal artery-
Pulmonary artery.
BRONCHIAL GLANDS
Intercostal artery
LEFT BRONCHUS
Left pulmonary vein
Descending aorta
PLEURA
Oblique vein
Left coronary artery
Coronary sinus
Left marginal branch of
left coronary artery
-Innominate artery
RIGHT
PNEUMOGASTRIC
NERVE
Vena cava superior
-Intercostal artery
RIGHT BRONCHUS
Intercostal artery
-Bronchial artery
POSTERIOR
PULMONARY PLEXUS
Right pulmonary artery
-Right pulmonary vein
-Vena azygos major
PLEURA
Left auricle
Ventricular branches of
coronary artery
Left ventricle
Posterior cardiac vein
-Posterior interventricular
branch of right coronary
artery
Relations. In front, it is in contact with the reflexion of the left pleura and the
root of the left lung (fig. 325).
Behind, it is in relation with the left side of the bodies of the fourth and fifth
thoracic vertebræ and the pleura.
To the right side are the oesophagus and thoracic duct, and the fourth and fifth
thoracic vertebræ.
To the left side are the left pleura and lung.
KK 2

500
KYO THE ARTERIES
Variations in the Arch of the Aorta
The variations that have been met with in the aortic arch are very numerous. Only the
chief can be here mentioned. They may be divided into:-1. Variations in the arch itself;
and 2. Variations in the number and arrangement of the three chief branches. The variations
in the coronary arteries are described under CORONARY ARTERIES, page 503.
(1) Variations in the Aortic Arch itself
The variations in the aortic arch itself may for the most part be traced to abnormalities
in development of the embryonic structures from which the three portions of the arch and
the pulmonary arteries and ductus arteriosus are derived, i.e. (a) the primitive ventral
aortic stem; (b) the fourth and fifth branchial arches; and (c) the dorsal aortic stems.
FIG. 325.-SCHEME OF THE RELATIONS OF THE THIRD PORTION OF THE
ARCH OF THE AORTA.
4
THORACIC DUCT
ESOPHAGUS
LEFT BRONCHUS.
LEFT LUNG AND PLEURA
Descending part of arch of
aorta
Left pulmonary artery
(a) Variations depending on Abnormalities in Development of the Ventral
Aortic Stem
These variations are closely associated with abnormalities of the pulmonary artery and
heart. They depend upon deficient development of the septum which normally divides
the anterior stem into the first portion of the aorta and the pulmonary artery. The follow-
ing are some of the chief variations:-
(1) The aorta and pulmonary artery may arise as a single stem from a simple heart.
The septum here is completely absent. The condition resembles the normal state in fishes.
(2) The aorta and pulmonary artery may be more or less conjoined, and the septum of
the heart incomplete. This is analogous to the normal condition in reptiles.
(3) The aorta and pulmonary artery may be transposed.
(4) The aorta or pulmonary artery may be in part obliterated, and the blood carried
into the remainder of the affected vessel through an abnormal opening beyond the
obliterated part.
(b) Variations depending on Abnormalities in Development of the Fourth
and Fifth Aortic or Branchial Arches
(1) The aorta may be double, the normal condition in amphibians, each arch giving off
a corresponding carotid and subclavian artery. This abnormality is explained by the
persistence of the right fourth aortic arch and right descending aortic stem, as well as the
corresponding parts on the left side. The trachea and cesophagus pass through the arterial
circle thus formed.
(2) The aortic arch may turn over the right bronchus instead of over the left. This is
the normal condition in birds, and is explained by the persistence of the right fourth
aortic arch and right descending aortic stem and the obliteration of the corresponding
parts on the left side.
(3) The pulmonary artery may be given off from the aorta. This condition is due to
the obliteration of the anterior part of the fifth branchial arch and the persistence of the
posterior part which normally constitutes the ductus arteriosus.

VARIATIONS IN ARCH OF AORTA
501
(c) Variations depending on Abnormalities in Development of the Dorsal
Aortic Stems

The right subclavian may arise from the third part of the arch of the aorta. It
then passes behind the trachea and oesophagus, and in front of the vertebral column, to
gain the interval between the scalene muscles. The explanation of this abnormality is
that the right fourth arch, from which the right subclavian is normally developed, is
obliterated, whilst the right posterior aortic stem remains pervious as far as the spot where
it normally joins the right fourth arch, the blood thus passing through the aortic stem
instead of the arch. The recurrent laryngeal nerve in these cases runs straight to the
larynx, since, the fourth arch being obliterated, the nerve is no longer hooked down by it.
The rudiments of the right stem frequently persist as the aberrans branch of the superior
intercostal artery and thoracic aorta.
In addition to the above variations, the arch of the aorta may be higher or lower in
the thorax than normal. In the former case it may cross the first bone of the sternum,
just below, or even a little above, the sternal notch, and reach the side of the second or
third thoracic vertebra instead of the fourth. In the latter case, that is, when it is situated
lower in the thorax than normal, it may cross the sternum below the level of the manu-
brium, and come into contact with the spine on a level with the fifth or sixth thoracic
vertebra.
2. The Chief Variations in the Three Primary Branches of the Transverse
Portions of the Aortic Arch
(1) All may arise from a common stem: a condition explained on the supposition that
the anterior aortic roots have become fused, and have so collected all the branches
together. A similar condition is normal in the horse. This variation is rare.
(2) They may arise as two stems: (a) One stem may be common to the right sub-
clavian, right carotid, and left carotid, the other stem being the left subclavian. This is
one of the commonest variations in the arrangement of the primary branches. It is the
normal condition in many mammals, and was formerly described as the normal condition
It is of some surgical interest, in that the left carotid when thus given off may
cross in front of the trachea. (b) One stem may be common to the left subclavian, left
carotid, and right carotid, the other stem being the right subclavian. In this variety the
right carotid passes in front of the trachea. (c) There may be two innominate arteries,
one stem forming the right, the other a left innominate artery as in birds. (d) One stem
may be common to the right and left carotid arteries, the other stem being the left
subclavian-the right subclavian in this case coming from the thoracic aorta.
(3) They may arise as three stems; but, in place of being given off in the normal way, (a)
the right and left subclavian may come off separately, and the carotids arise by a common
stem between the subclavians. This is the normal condition in some cetaceans. (b) The
right subclavian and right carotid may arise separately, the left carotid and left subclavian
forming a left innominate stem. (c) The innominate may give off the left carotid, the
left vertebral, and left subclavian, the other two vessels arising from the arch.
(4) They may arise as four stems, which may be given off in the following order: (a)
innominate, left carotid, left vertebral, left subclavian (the commonest condition); (b) right
carotid, left carotid, left subclavian, right subclavian; (c) right subclavian, right carotid,
left carotid, left subclavian-the normal condition in the walrus and wombat.
(5) They may arise as five stems, the five branches being given off in the following
order: (a) right subclavian, right carotid, left carotid, left vertebral, left subclavian; (b)
right carotid, left carotid, left vertebral, left subclavian, right subclavian; (c) right carotid,
left carotid, left subclavian, left vertebral, right subclavian; (d) right subclavian, right
external carotid, right internal carotid, left common carotid, left subclavian; (e) innominate,
right vertebral, left carotid, left vertebral, left subclavian.
(6) They may arise as six stems, given off as follows: right subclavian, right vertebral,
right carotid, left carotid, left vertebral, left subclavian.

BRANCHES OF THE ARCH OF THE AORTA
doctord zeleo
1. The ascending portion gives off-(1) Right coronary; (2) left coronary.
2. The transverse portion gives off-(1) Innominate; (2) left common carotid;
(3) left subclavian.
3. The descending portion gives off no branch.

502
THE ARTERIES
I. The branches of the first, or ascending, portion of the arch of the aorta are
the right and left coronary for the supply of the tissues of the heart. They come off
from the aorta, immediately above the aortic valves, from two of the dilatations
known as the sinuses of Valsalva.
THE RIGHT CORONARY ARTERY
The right coronary artery (figs. 321, 326) arises from the right anterior sinus
of Valsalva, and, passing forwards and to the right between the right auricular
appendix and the pulmonary artery, turns to the right, and courses in the right
auriculo-ventricular groove to the back of the heart, where it follows the poste-
rior interventricular groove to the apex of the ventricles, giving off, however, a
small transverse branch, which continues in the groove between the left auricle
and ventricle to anastomose with the terminal branch of the left coronary artery.
FIG. 326.-SCHEME OF THE CORONARY ARTERIES.
Posterior interventricular
branch of right coronary
artery
AURICULAR APPENDAGE
Right coronary artery
RIGHT
AURICLE
Preventricular branch
Right marginal branch
Posterior interventricular
branch of right coronary
artery
ENA CAVA SUPERIOR
AORTA
PULMONARY
ARTERY
LEFT
AURICLE
Transverse branch of right
coronary artery
-Terminal branch of left
coronary artery
-Left coronary artery
RIGHT
LEFT
VENTRICLE
VENTRICLE
Anterior interventricular
branch of left coronary
artery
Left marginal branch
In this course it gives off the following branches: (a) A right auricular branch
(fig. 326), which turns backwards and upwards between the right auricle and the
aorta, supplying the structures between which it runs and the auricular septum;
(b) a preventricular branch (fig. 326), which runs down the front of the right
ventricle, supplying its walls; (c) a right marginal branch (fig. 326), which courses
down the right margin of the right ventricle; (d) a posterior interventricular
branch, or the continuation of the coronary trunk, which passes down the poste-
rior interventricular groove, giving twigs to each ventricle and the interventricular
septum, and anastomosing at the apex of the heart with the anterior interventri-
cular branch of the left coronary artery; and (e) the transverse branch, which runs
in the left auriculo-ventricular groove to anastomose with the terminal branch of the
left coronary (fig. 326).

THE INNOMINATE ARTERY
503
THE LEFT CORONARY ARTERY
The left coronary artery (figs. 321, 326), a little larger than the right, arises
from the left anterior sinus of Valsalva, and, passing forwards and to the left
between the pulmonary artery and left auricular appendix, courses round the heart
in the left auriculo-ventricular groove to anastomose with the transverse branch of
the right coronary artery. It gives off the following branches: (a) A left auricular
branch, which supplies the left auricle, the pulmonary artery, and the commence-
ment of the aorta. (b) A large anterior interventricular branch, which is larger
than the continuation of the vessel between the auricle and ventricle, and is
regarded by some as the main trunk of the left coronary artery. It courses down-
wards in the anterior interventricular groove to the apex of the heart, where it
forms a slight anastomosis with the posterior interventricular branch of the right
vessel (fig. 324). It supplies both ventricles and the interventricular septum. (c) A
left marginal branch, which runs down the left margin of the heart, supplying
branches to the walls of the ventricle. (d) The terminal branch, the continuation
of the vessel, anastomoses with the transverse branch of the right coronary artery.

Variations in the Coronary Arteries
(a) They may arise as a common trunk. (b) They may both arise from the same
sinus of Valsalva. (c) The interventricular and terminal branches of the left coronary
may arise separately from the sinus of Valsalva. (d) One coronary artery may be larger
than usual; the other vessel is then correspondingly small. (e) An extra coronary artery
may arise from the pulmonary artery.
II. From the transverse part of the aortic arch are given off the innominate, the
left common carotid, and the left subclavian arteries. The innominate and left
carotid arise close together-indeed, so close that, when seen from the interior
of the aorta, the orifices appear merely separated by a thin septum. The left
subclavian arises a little less close to the left carotid.

THE INNOMINATE ARTERY
The innominate or brachio-cephalic artery (fig. 321), the largest branch of the
arch of the aorta, extends from near the commencement of the transverse portion,
upwards and a little forwards and to the right, as high as the upper limit of the
right sterno-clavicular joint where it bifurcates into the right common carotid and
right subclavian arteries. It lies obliquely in front of the trachea, and measures
from an inch and a half to two inches in length (about 4 cm.).
Relations. In front of the artery (fig. 327) are the manubrium, the origins
of the sterno-hyoid and sterno-thyroid muscles, the right sterno-clavicular joint
and the remains of the thymus gland. The left innominate vein crosses the root
of the vessel, and the inferior thyroid veins descend obliquely over it to end in
the left innominate vein. The inferior cervical cardiac branches of the right
pneumogastric pass in front of it on their way to the deep cardiac plexus.
Behind, it lies on the trachea, crossing that tube obliquely from left to right, and
coming into contact above with the right pleura.
To the right side are the right innominate vein, the right pneumogastric nerve,
and the pleura.
To the left side are the left common carotid, the remains of the thymus gland,
the inferior thyroid veins; and higher, the trachea.

504
THE ARTERIES
Variations in the Innominate Artery
The variations in the innominate artery are of surgical interest. (a) It may divide
lower than normal, thus decreasing the available space for the application of a ligature to
it, but at the same time increasing the length of the first portion of the right subclavian
artery. (b) It may divide higher than usual, and may then incline abnormally to the
left, mounting in front of the trachea above the sternum. Under these circumstances it
is in danger in the low operation of tracheotomy. (c) When abnormally long and inclining
to the left, it may pass behind the trachea or the oesophagus to gain the right side. (d) It
may give off the thyroidea ima artery, and, more rarely the vertebral, the internal
mammary or a smaller twig, as a bronchial, thymic, pericardiac, or tracheal branch.
The branches of the innominate artery are: (1) The right common carotid; and
(2) the right subclavian. These are terminal branches. There are usually no col-
lateral branches from this vessel, but at times the thyroidea ima may arise from it.
FIG. 327.-SCHEME OF THE RELATIONS OF THE INNOMINATE ARTERY.
I, a little above origin; II, a little below bifurcation.
I
ed
CARDIAC NERVE
RIGHT PNEUMO-
GASTRIC NERVE
Innominate artery
RIGHT LUNG AND PLEURA
Right innominate vein,.
divided transversely
at its junction with
the left innominate
vein
RIB
II
TRACHEA
G
Left common carotid
artery
Inferior thyroid vein
Inferior thyroid vein
Left innominate vein
STERNUM
RIGHT LUNG AND PLEURA-
RIGHT PNEUMO--
GASTRIC NERVE
Right innominate vein
Innominate artery-
O
TRACHEA
-Left common carotid artery
Inferior thyroid vein
Sterno-hyoid and
Sterno-thyroid muscles
CARDIAC NERVES-
CLAVICLE
STERNUM
THE COMMON CAROTID ARTERIES
The common carotid arteries pass up deeply from the thorax on either side of
the neck to about the level of the upper border of the thyroid cartilage, where they
divide into the external and internal carotid arteries. The external carotid supplies
the structures at the upper part of the front and side of the neck, the larynx,
pharynx, tongue, face, the upper part of the back of the neck, the structures in
the pterygoid region, the scalp, and in chief part the membranes of the brain.
The internal carotid gives off no branch in the neck, but enters the cranium
and supplies the greater part of the brain, the structures contained in the orbit,
and portions of the membranes of the brain.
The common carotid artery on the right side arises from the bifurcation of

THE COMMON CAROTID
505
the innominate behind the sterno-clavicular joint; on the left side from the arch
of the aorta a little to the left of the innominate artery, and on a somewhat
posterior plane to that vessel (fig. 321). The portion of the left common carotid
artery which extends from the arch of the aorta to the level of the sterno-clavicular
articulation lies deeply in the chest, and requires a separate description; but
above the level of the sterno-clavicular joint the relations of the right and left
carotids are practically the same, and are given under the account of the right
common carotid.
THORACIC PORTION OF THE LEFT COMMON CAROTID ARTERY
Within the thorax the left common carotid is deeply placed behind the first bone
of the sternum, and is overlapped by the left lung and pleura. It arises from the
middle of the transverse portion of the aortic arch, close to the left side of the
innominate artery, and a little posterior to that vessel, and ascends obliquely in front
of the trachea to the left sterno-clavicular articulation, above which its relations
are similar to those of the right common carotid.
FIG. 328.-SCHEME OF THE RELATIONS OF THE LEFT COMMON CAROTID AND LEFT
SUBCLAVIAN ARTERIES WITHIN THE THORAX.
I, just above origin' II, just below level of sterno-clavicular joint.
I
TRACHEA
Left subclavian artery
THORACIC DUCT
Left common carotid
artery
Innominate artery.
CARDIAC NERVES-
Right innominate vein-
CESOPHAGUS
RECURRENT LARYNGEAL
NERVE
Inferior thyroid veins
Innominate artery
TRACHEA
STERNUM
II
LEFT PNEUMOGASTRIC
NERVE
Left innominate vein
-Inferior thyroid veins
REMAINS OF THYMUS GLAND
REMAINS OF THYMUS GLAND
STERNUM
THORACIC DUCT
Left subclavian artery
LUNG AND PLEURA
LEFT PNEUMO-
GASTRIC NERVE
Left common carotid
artery
-Left innominate vein
Sterno-hyoid and
Sterno-thyroid muscles
Relations. In front, but at some little distance, are the manubrium and
the origins of the sterno-hyoid and sterno-thyroid muscles; whilst in contact
with it are the remains of the thymus gland, and the loose connective tissue and
fat of the superior mediastinum. Crossing its root is the left innominate vein.
Behind, it lies successively upon the trachea, the oesophagus (which here inclines
a little to the left), the thoracic duct, and the recurrent laryngeal nerve.
506
THE ARTERIES
To its right side is the root of the innominate artery, and higher up are the
trachea and the inferior thyroid veins.
To its left side, but on a posterior plane, are the left subclavian artery and the
left pneumogastric nerve; and, slightly overlapping it, the edge of the left pleura
and lung (fig. 328).
The variations in the origin of the left common carotid are given under VARIATIONS OF
THE ARCH OF THE AORTA (page 500).
THE COMMON CAROTID ARTERY IN THE NECK
The common carotid artery in the neck extends from the sterno-clavicular
articulation to the upper border of the thyroid cartilage on a level with the fourth
cervical vertebra where it divides into the external and internal carotid arteries.
A line drawn from the sterno-clavicular joint to the interval between the mastoid
process and the angle of the jaw would indicate its course. The artery is at first
deeply placed beneath the sterno-mastoid, sterno-hyoid, and sterno-thyroid muscles,
and at the level of the top of the sternum is only three-quarters of an inch
(2 cm.) distant from its fellow of the opposite side, and merely separated from
it by the trachea. As the carotid arteries run up the neck, however, they diverge
in the form of a V and become more superficial, though on a plane posterior to that
in which they lie at the root of the neck, and are separated from each other by the
larynx and pharynx. At their bifurcation they are about two inches and a quarter
(6 cm.) apart. The common carotid is contained in a sheath of fascia common
to it and the internal jugular vein and pneumogastric nerve. The artery, vein,
and nerve, however, are not in contact, but separated from each other by fibrous
septa, which divide the common sheath into three compartments: one for the
artery, one for the vein, and one for the nerve. The vein, which is larger than
the artery, lies to the outer side, and somewhat overlaps the artery. The pneumo-
gastric nerve lies behind and between the two vessels. The vessel on the right
side measures about three and three-quarter inches (9.5 cm.), on the left side about
four and three-quarter inches (12 cm.).
Relations. In front the artery is covered by the skin, superficial fascia, platysma,
and deep fascia, and is more or less overlapped by the sterno-mastoid muscle.
At the lower part of the neck it is covered in addition by the sterno-hyoid and
sterno-thyroid muscles, and is crossed by the anterior jugular vein, and is often
overlapped by the thyroid body. Opposite the cricoid cartilage it is crossed obliquely
by the omo-hyoid muscle; and above this spot by the middle and superior thyroid,
the lingual, and generally the facial veins in their course to the internal jugular,
and by the middle sterno-mastoid artery as it passes from the superior thyroid artery,
its usual source, on its way down to the sterno-mastoid muscle. The descendens
hypoglossi nerve generally descends in front of the carotid sheath, being there joined
by the communicantes hypoglossi, one or two small branches of the second and third
cervical nerves. At times this nerve runs within the sheath. There are usually two
lymphatic glands about the bifurcation of the artery. These are often found
enlarged and infiltrated in cancer of the lip and tongue.
Behind, the common carotid lies on the longus colli below, and rectus capitis
anticus major above. Posterior to the artery, but in the same sheath, is the pneumo-
gastric nerve; and posterior to the sheath, the chain of the sympathetic and the
cervical cardiac branches of the sympathetic and pneumogastric nerves. At the lower
part of the neck the inferior thyroid artery courses obliquely behind the carotid, as
does likewise the recurrent laryngeal nerve.
Internally, from below upwards, are the trachea and oesophagus, with the recur-
rent laryngeal nerve in the groove between them, and the terminal branches of the


THE COMMON CAROTID
507
FIG. 329. THE COMMON CAROTID, THE EXTERNAL AND INTERNAL CAROTID AND THE
SUBCLAVIAN ARTERIES OF THE RIGHT SIDE AND THEIR BRANCHES.
(From a dissection by Dr. Alder Smith in the Museum of St. Bartholomew's Hospital.)
Stylo-glossus
INFERIOR DENTAL NERVE
CHORDA TYMPANI
FACIAL NERVE
Internal maxillary artery
Stylo-hyoid, turned up
Digastricus, turned up
Temporal artery
Posterior auricular artery
Internal jugular vein
SECOND CERVICAL NERVE
SPINAL ACCESSORY NERVE
Rectus capitis anticus major
Stylo-pharyngeus muscle.
SUP. CER. GANGLION OF SYMPATHETIC.
GLOSSO-PHARYNGEAL NERVE.
Sterno-mastoid, reflected-
Occipital artery
Internal carotid
Levator anguli scapulæ
THIRD CERVICAL NERVE-
DESCENDENS HYPOGLOSSI
NERVE
External carotid
Inferior constrictor-
COMMUNICANTES HYPOGLOSSI
FOURTH CERVICAL NERVE
Ascending cervical artery.
SPINAL ACCESSORY-
PHRENIC NERVE
Scalenus anticus
Levator anguli scapulæ
FIFTH CERVICAL NERVE-
Scalenus medius"
CERV. PLEXUS DES. BRANCH'
PNEUMOGASTRIC NERVE
BRACHIAL PLEXUS
(SIXTH CERVICAL)
Internal jugular vein-
Superficial cervical artery
Suprascapular artery'
Serratus magnus
Coraco-brachialis
Submental artery
Facial artery
MYLO-HYOID NERVE
LOWER JAW, TURNED UP
SUBMAXILLARY GANGLION
USTATORY NERVE
SUBMAXILLARY DUCT
SUBMAXILLARY GLAND
TONGUE
HYPOGLOSSAL NERVE
Ranine artery
Genio-hyo-glossus
Sublingual artery
-Lingual artery
Artery of frænum
LOWER JAW
Genio-hyoid
-Hyo-glossus
Lingual artery
Hyoid branch
Mylo-hyoid muscle
Thyro-hyoid membrane
SUPERIOR LARYNGEAL
NERVE
Superior laryngeal artery
Thyro-hyoid
Superior thyroid artery
Omo-hyoid
EXTERNAL LARYNGEAL
NERVE
THYROID GLAND
Sterno-hyoid
Common carotid
Sterno-thyroid
Vertebral artery
Inferior thyroid artery
Anterior jugular vein
Common carotid
CLAVICLE
Vertebral vein
BRACHIAL PLEXUS
(SEVENTH CERVICAL)
Subclavian artery
Pectoralis major, reflected
Suprascapular artery given off from third
part of subclavian
Posterior scapular artery
SUPRASCAPULAR NERVE
Humeral thoracic artery
Posterior belly of omo-hyoid, drawn down
Transverse cervical artery
Subclavius, reflected
BRACHIAL PLEXUS (EIGHTH CERVICAL)
Pectoral branch of acromial thoracic artery
Subclavian vein
Pectoralis minor
inferior thyroid artery, the lateral lobe of the thyroid body, the cricoid cartilage,
the thyroid cartilage, and the lower part of the pharynx. At the angle of bifurcation
is a vascular structure known as the ganglion intercaroticum or the carotid gland.

508
THE ARTERIES
FIG. 330.-THE COLLATERAL CIRCULATION AFTER LIGATURE OF THE COMMON CAROTID
AND SUBCLAVIAN ARTERIES.
(A ligature is placed on the common carotid and on the third portion of the subclavian artery.)
Right anterior cerebral-
Internal carotid-
Right posterior cerebral-
Left anterior cerebral
Anterior communicating
Posterior communicating
Left posterior cerebral
Basilar
Transverse cervical-
Posterior scapular-
Acromial branch
Subscapular branch
Supraspinous branch
Anterior circumflex-
Infraspinous branch-
Posterior circumflex-
Long thoracic-
Subscapular
Dorsal scapular-
Infrascapular-
Subscapular
Occipital-
Princeps cervicis-
External carotid-
Anterior spinal
Vertebral
Facial
Lingual
Superficial branch of
princeps cervicis
Deep branch.
Ascending cervical.
-Superior thyroid
Deep cervical-
Superficial cervical-
Inferior thyroid
Common carotid
Thyroid axis
Superior intercostal
Innominate
Superior intercostal
Left common carotid
Left subclavian
Short thoracic
Internal mammary
-Anterior intercostal
First aortic inter-
costal
Second aortic inter-
costal
Anterior intercostal
Third aortic inter-
costal
Externally are the internal jugular vein and the pneumogastric nerve. On the
right side, at the root of the neck, the vein diverges somewhat from the artery,
leaving a space in which the pneumogastric nerve and vertebral artery are exposed.
On the left side the vein approaches and somewhat overlaps the artery, thus leaving
no corresponding interval to that on the right side.

THE COMMON CAROTID
509
to The cricoid cartilage is as a rule taken as the centre of the incision in the opera-
tion for ligature of the common carotid artery. The incision is made in the line of the
vessel parallel to the anterior margin of the sterno-mastoid muscle. The omo-hyoid
forms one of the chief rallying points in the course of the operation for ligature of
the artery above that muscle, the usual situation. The artery is found beating at the
angle formed by the omo-hyoid with the sterno-mastoid.
Branches. (1) External and (2) internal carotid arteries. The common carotid
gives off no lateral branches, and consequently does not diminish in size as it runs
up the neck. It is often a little swollen just below its bifurcation.
Variations of the Common Carotid Arteries
The variations in the origin of the common carotid have been already mentioned
under VARIATIONS OF THE CHIEF BRANCHES OF THE AORTIC ARCH (page 501).
The following variations are of surgical interest:-
(A) The artery may cross obliquely the lower part of the trachea above the level of the
sternum. This may occur on the right side: (a) when the innominate is situated abnormally
to the left of the middle line; (b) when the right common carotid arises as the second branch
of the aortic arch; and (c) when the right and left common carotids arise as a common
stem from the aorta. On the left side: when the left common carotid arises from the
innominate.
(B) The right common carotid may, when arising from the aorta, run behind the
trachea and oesophagus to the right side of the neck.
(C) The commencement of the right common carotid may be above or below the
usual spot, according as the innominate bifurcates higher or lower than usual. A low
bifurcation of the innominate is somewhat the more common abnormality.
(D) The common carotid may run in a very tortuous manner, forming one or more
distinct loops in its course up the neck.
(E) The artery may bifurcate higher or lower than normal. A high bifurcation is the
more common. The bifurcation may occur as high as the hyoid bone, or even styloid
process; or as low as the cricoid cartilage, or within an inch and a half of its origin.
(F) The artery may not bifurcate, but give off the branches usually derived from the
external division as it ascends in the neck.
(G) The common carotid may be absent, the external and internal carotids arising
directly from the aorta.
(H) It may give off one or more of the branches usually derived from the external
carotid.


(I) It may give off a thyroidea ima.
(J) The pneumogastric nerve may run in front of the artery instead of behind it.
The collateral circulation (fig. 330), after ligature of the common carotid, is carried on
chiefly by the anastomosis of the internal carotid with the internal carotid of the opposite
side through the circle of Willis; by the vertebral with the opposite vertebral; by the inferior
thyroid with the superior thyroid; by the deep cervical branch of the superior intercostal
with the princeps cervicis of the occipital; by the superior thyroid, lingual, facial, occipital
and temporal, with the corresponding arteries of the opposite side, and by the ophthalmic
with the angular.

THE EXTERNAL CAROTID ARTERY
The external carotid artery, the smaller of the two branches into which the
common carotid divides at the upper border of the thyroid cartilage, is distributed
to the anterior part of the neck, the face, and the side of the head both soft parts and
bones, the integuments externally, and dura mater internally. It is development-
ally derived from the third aortic arch, and supplies the oral and post-oral visceral
branches. It is at first situated internal to the internal carotid; but as it ascends
in the neck it forms a gentle curve, with its convexity forwards, and, running slightly
backwards as well as upwards, terminates opposite the neck of the jaw just below
the condyle, by dividing into the internal maxillary and temporal arteries. It here
lies superficial to the internal carotid, from which it is separated by a portion of
the parotid gland. At its origin it is overlapped by the anterior margin of the
sterno-mastoid, and is covered by the superficial fascia, platysma, and deep fascia.
510
CE THE ARTERIES
Higher up the neck it passes beneath the stylo-hyoid muscle, the posterior belly of
the digastric muscle, and the hypoglossal nerve; and, entering the parotid gland, is
situated deeply in that structure at its division into its terminal branches. It is
separated from the internal carotid artery posteriorly by the stylo-pharyngeus and
stylo-glossus muscles, the glosso-pharyngeal nerve, the pharyngeal branch of the
pneumogastric nerve, a portion of the parotid gland, and the stylo-hyoid ligament;
or, if the styloid process is abnormally long, by that process itself. It measures
about two and a half inches (6.5 cm.).
Relations (fig. 329).-In front, in addition to the skin, superficial fascia,
platysma, and deep fascia, it has the hypoglossal nerve, the lingual and facial veins,
the posterior belly of the digastricus and stylo-hyoid muscles, the temporo-maxillary
vein, the superior cervical lymphatic glands, branches of the facial nerve, and the
parotid gland. The sterno-mastoid also overlaps it in the natural state of the parts.
Behind, it is in relation with the internal carotid, from which it is separated
by the stylo-glossus and stylo-pharyngeus muscles, the glosso-pharyngeal nerve, the
pharyngeal branch of the pneumogastric nerve, the stylo-hyoid ligament, and the
parotid gland. The superior laryngeal nerve crosses behind both the external and
internal carotid arteries.
Internally, it is in relation with the hyoid bone, the pharyngeal wall, the ramus
⚫ of the jaw, the stylo-maxillary ligament which separates it from the submaxillary
gland, and the parotid gland.
Externally, in the first part of its course, it is in contact with the internal carotid
artery.
Chief Variations of the External Carotid Artery
The variations of the external carotid artery are not of much surgical importance. The
variations in its origin have been discussed under VARIATIONS OF THE COMMON CAROTID.
(A) It may be absent, the branches usually derived from it coming off from the upward
continuation of the common trunk.
(B) It may run superficial to the stylo-hyoid muscle.
(C) Its branches may come off irregularly; or may be diminished or increased in
number either by two or more arising as a common stem, or by its giving origin to branches
not usually derived from it, as the sterno-mastoid branch of either the superior thyroid or
occipital artery.
(D) At times all its branches come off close together just above its origin.
The branches of the external carotid are usually given off in the following order,
from below upwards :-

1. Ascending pharyngeal
2. Superior thyroid.
3. Lingual
4. Facial
5. Occipital
6. Posterior auricular
7. Temporal
8. Internal maxillary
Ascending set.
Anterior set.
Posterior set.
Terminal set.

1. THE ASCENDING PHARYNGEAL ARTERY
The ascending pharyngeal artery is usually the first or second branch of the u
external carotid. Occasionally it comes off at the bifurcation of the common
carotid from the common carotid itself. It is a long slender vessel, the smallest
named branch of the external carotid, and runs deeply seated up the neck to the
base of the skull, having the walls of the pharynx internally, the internal carotid

THE ASCENDING PHARYNGEAL
511
artery externally, and the vertebral column, the rectus capitis anticus major, and
the sympathetic nerve posteriorly. In front it is crossed by the stylo-pharyngeus
muscle and glosso-pharyngeal nerve.
BRANCHES OF THE ASCENDING PHARYNGEAL ARTERY
The ascending pharyngeal artery gives off the following branches :-(1) Pre-
vertebral; (2) pharyngeal; (3) palatine; (4) tympanic; (5) meningeal.
(1) The prevertebral are distributed to the recti muscles, the fascia in front of
the vertebral column, and to the sympathetic nerve and lymphatic glands. These
FIG. 331.-SCHEME OF ASCENDING PHARYNGEAL ARTERY.
Meningeal branch passing
through middle lacerated
The internal carotid artery is hooked aside.
Intracranial part of internal
carotid
foramen
Tympanic branch
Meningeal branch passing
through jugular foramen
Meningeal branch passing
through anterior condyloid
foramen
Stylo-
pharyngeus
GLOSSO-PHARYNGEAL
NERVE
Occipital artery
Rectus capitis anticus
major
Ascending pharyngeal
artery
Middle constrictor of
pharynx
SYMPATHETIC
NERVE
Internal carotid artery
External carotid artery
Intraosseous part of internal
carotid
Levator palati
Palatine branch
Superior constrictor
of pharynx
Pterygo-maxillary
ligament
Stylo-glossus muscle
Ascending palatine branch
of facial artery
Tonsillar branch
Hyo-glossus muscle
Facial artery
Lingual artery
Superior thyroid artery
Common carotid artery
branches anastomose with branches of the ascending cervical. (2) The pharyngeal
supply the superior and middle constrictor muscles and the mucous membrane
lining them. These vessels anastomose with branches of the superior thyroid.
(3) The palatine passes over the upper edge of the superior constrictor to the soft
palate and its muscles. This branch follows a course similar to that taken by
the ascending palatine artery, and when the latter is small may take its place.
It generally gives off small twigs to the Eustachian tube and tonsil. (4) The
tympanic accompanies the tympanic branch of the glosso-pharyngeal nerve
through the tympanic canaliculus into the tympanum, and anastomoses with the
other tympanic arteries. (5) The meningeal are distributed to the membranes
of the brain. Some of these pass with the jugular vein through the jugular
foramen into the cranium, and supply the dura mater in the posterior fossa of

512
HOW THE ARTERIES
the skull. Others occasionally reach the same fossa through the anterior condyloid
foramen; while others pass through the cartilage of the middle lacerated foramen
and supply the middle fossa of the skull.
2. THE SUPERIOR THYROID ARTERY
The superior thyroid artery arises from the front of the external carotid a
little above the origin of that vessel, and, coursing forwards, inwards, and then
downwards, in a tortuous manner, supplies the depressor muscles of the hyoid bone,
the larynx, the thyroid body, and the lower part of the pharynx. The artery at
first runs forwards and a little upwards, just beneath the greater cornu of the
FIG. 332.-SCHEME OF SUPERIOR THYROID ARTERY.
Facial artery
Lingual artery
Supra-hyoid branch
Infra-hyoid branch
- External carotid artery
Ascending pharyngeal artery
Internal carotid artery
Superior laryngeal branch
Sterno-mastoid branch
Superior thyroid artery
Crico-thyroid branch
Common carotid artery
Inferior thyroid artery
hyoid bone. In this part of its course it lies in the superior carotid triangle, and is
quite superficial, being covered only with the integument, fascia, and platysma.
It next turns downwards, and passes beneath the omo-hyoid, sterno-hyoid, and
sterno-thyroid muscles, and ends at the upper part of the thyroid body by breaking
up into branches, some of which pass downwards in front, and others behind the
lateral lobe of that structure to anastomose with ascending branches from the
inferior thyroid; whilst others, again, but much smaller in size, pass in the substance
of the isthmus across the front of the trachea to anastomose with the superior
thyroid artery of the opposite side. These vessels, however, are so small, that if the
isthmus is divided accurately in the middle line, there is practically no arterial
hæmorrhage. From the branch to the thyroid body twigs are given off to the
inferior constrictor and the upper part of the oesophagus. These anastomose with
SUPERIOR THYROID-LINGUAL
513
branches from the inferior thyroid. The superior thyroid vein passes beneath the
artery on its way to the internal jugular vein. The superior thyroid is the artery
most commonly divided in cases of suicidal wounds of the throat.
BRANCHES OF THE SUPERIOR THYROID ARTERY
The named branches of the superior thyroid artery are:-(1) The hyoid; (2) the
sterno-mastoid; (3) the superior laryngeal; and (4) the crico-thyroid.
(1) The hyoid-or infra-hyoid branch as it is sometimes called, usually a small
twig-passes along the lower border of the hyoid bone, lying on the thyro-hyoid
membrane under cover of the thyro-hyoid and sterno-hyoid muscles. It supplies
the infra-hyoid bursa, and the thyro-hyoid muscle, and anastomoses with its fellow
of the opposite side, and with the supra-hyoid branch of the lingual. When the
latter artery is small, the infra-hyoid is usually comparatively large, and vice

versa.
(2) The sterno-mastoid (fig. 332)-or middle mastoid artery as it is occasionally
called-courses downwards and backwards across the carotid sheath, and entering
the sterno-mastoid supplies the middle portion of that muscle. It gives off slender
twigs to the thyro-hyoid, sterno-hyoid, and omo-hyoid muscles, and the platysma
and integuments covering it. At times the vessel arises directly from the external
carotid. It lies usually somewhere in the upper part of the incision for tying the
common carotid, above the omo-hyoid muscle.
(3) The superior laryngeal (fig. 329) passes inwards and forwards beneath
the thyro-hyoid muscle, and, perforating the thyro-hyoid membrane along with the
superior laryngeal nerve, supplies the intrinsic muscles and mucous lining of the
larynx. Its further distribution within the larynx is given with the description of
that organ.
This branch sometimes arises from the external carotid direct. It
may enter the larynx by passing through a foramen in the thyroid cartilage.
(4) The crico-thyroid-or inferior laryngeal branch as it is sometimes called,
usually insignificant in size-passes across the crico-thyroid membrane immediately
beneath the lower border of the thyroid cartilage. It anastomoses with its fellow
of the opposite side, and usually sends a small branch through the membrane
into the interior of the larynx. It has, however, frequently been seen of com-
paratively large size-once as large as the radial, and crossing the membrane
obliquely. In order to avoid injuring the crico-thyroid artery in the operation of
laryngotomy, it is usual, if the operation has to be done in a hurry, to make the
incision through the crico-thyroid membrane in a transverse direction, and as near
to the cricoid cartilage as possible.

3. THE LINGUAL ARTERY
The lingual artery (fig. 333) arises from the front of the external carotid,
between the superior thyroid and facial arteries, often, as a common trunk with
the latter vessel, and nearly opposite or a little below the greater cornu of the hyoid
bone. It may, for purposes of description, be divided into three portions: the first,
or oblique, extends from its origin to the outer edge of the hyo-glossus muscle; the
second, or horizontal, lies beneath the hyo-glossus; the third, or ascending, beneath
the tongue. The first or oblique portion is situated in the superior carotid
triangle, and is superficial, being covered merely by the integuments, platysma,
and deep fascia. Here it lies on the middle constrictor muscle and superior
laryngeal nerve.
After ascending a short distance, it curves downwards and
forwards beneath the hypoglossal nerve, and, in the second part of its course, runs
horizontally along the upper border of the hyoid bone, beneath the hyo-glossus.
LL

514
THE ARTERIES
by which it is separated from the hypoglossal nerve, the posterior belly of the
digastricus and the stylo-hyoid muscles, and the lingual vein. In this part of its
course it lies successively on the middle constrictor of the pharynx and the genio-
hyo-glossus muscle. In the third part of its course it ascends tortuously, usually
beneath the anterior margin of the hyo-glossus, to the under surface of the tongue,
FIG. 333.-SCHEME OF THE LINGUAL ARTERY.
Palato-glossus
Descending palatine
Palato-pharyngeus
TONSIL
Ascending palatine branch
of facial
Tonsillar branch of.
dorsalis linguæ
Tonsillar branch of facial.
Stylo-glossus
Dorsalis linguæ artery.
Middle constrictor
HYPOGLOSSAL NERVE
Facial artery
Posterior belly of
digastric and
stylo-hyoid
Supra-hyoid branch
SUP. LARYNGEAL N.
Infra-hyoid branch
Internal carotid artery
TONG-UE
External carotid artery
Common carotid artery
JAW
Ranine artery
Genio-hyo-
glossus muscle
Artery of
frænum
Hyo-glossus
Sublingual artery
Genio-hyoid
Anterior belly
of digastric
Submental
artery
Superior thyroid artery
and is thence continued to the tip of that structure lying between the lingualis
and the genio-hyo-glossus muscles. From the anterior edge of the hyo-glossus to
its termination, it is only covered by the mucous membrane of the under surface
of the tongue. This part of the vessel is sometimes called the ranine artery.
BRANCHES OF THE LINGUAL ARTERY
The named branches of the lingual artery are:-(1) The hyoid; (2) the dorsalis
linguæ; (3) the sublingual; and (4) the ranine.
(1) The hyoid, or supra-hyoid (fig. 333), is a small vessel which arises from the
first part of the lingual, and courses along the upper border of the hyoid bone,
superficial to the hyo-glossus, but beneath the insertion of the posterior belly of
the digastricus and stylo-hyoid. It anastomoses with its fellow of the opposite
side, and with the infra-hyoid, a branch of the superior thyroid artery, and
supplies the contiguous muscles.
(2) The dorsalis linguæ (fig. 333) arises from the second portion of the lingual
artery, usually under cover of the posterior edge of the hyo-glossus muscle. It
ascends to the back of the dorsum of the tongue, and, dividing into branches,
supplies the mucous membrane on each side of the V formed by the circumvallate
papillæ. It also supplies the pillars of the fauces and the tonsil, where it anasto-
moses with the other faucial and tonsillar arteries. Instead of a single artery, as
above described, there may be several small vessels running directly to the parts
mentioned. The artery anastomoses in the mucous membrane by very small branches
with the vessel of the opposite side; but the anastomosis is so minute that when
one lingual artery is injected, the injection merely passes across to the opposite
LINGUAL-FACIAL
515
side at the tip of the tongue; and when the tongue is divided accurately in the
middle line, as in the removal of one half of that organ, practically no hæmorrhage
occurs.
(3) The sublingual artery (fig. 333) usually comes off from the lingual at the
anterior margin of the hyo-glossus. It passes beneath the mylo-hyoid to the
sublingual gland, which it supplies, and, perforating the muscle, anastomoses
with the submental artery, a branch of the facial. It also supplies branches to
the side of the tongue, and gives off a terminal twig, which anastomoses beneath
the mucous membrane of the floor of the mouth (to which it also gives twigs) with
the artery of the opposite side. The artery of the frænum is usually derived from
this vessel (fig. 333).
(4) The ranine artery, the termination of the lingual, courses forwards beneath
the mucous membrane, on the under surface of the tongue, to the tip. It lies
external to the genio-hyo-glossus, between that muscle and the inferior lingualis,
and is accompanied by the ranine vein and terminal branch of the gustatory nerve.
It follows a very tortuous course, so that it is not stretched when the tongue is
protruded. Branches are given off from it to the contiguous muscles and mucous
membrane. Near the tip of the tongue it communicates with its fellow of the oppo-
site side, as shown by the fact that when the lingual artery of one side is injected
the injection fluid passes into the branches of the artery of the other side.
4. THE FACIAL ARTERY
The facial artery (fig. 334)-also called the external maxillary-arises imme-
diately above the lingual from the fore part of the external carotid, at times
as a common trunk with the lingual. It courses forwards and upwards in a
tortuous manner to the lower jaw, and, passing over the body of this bone at the
anterior edge of the masseter muscle, winds obliquely upwards and forwards over
the face to the inner canthus of the eye, where it inosculates, under the name of
the angular artery, with the nasal branch of the ophthalmic. It is usually divided
into two portions-the cervical and the facial.
The cervical portion (fig. 334) ascends tortuously from its origin from the
external carotid upwards and forwards beneath the posterior belly of the digastric
and stylo-hyoid muscles, and usually also beneath the hypoglossal nerve, and then
making a turn runs horizontally forwards for a short way beneath the jaw, either
imbedded in or lying under the submaxillary gland. It has here the mylo-hyoid and
stylo-glossus beneath it. On leaving the cover of the gland it forms a loop passing
first downwards and then upwards over the lower border of the jaw immediately in
front of the masseter muscle, where it is superficial, being merely covered by the in-
tegument and platysma. Here it can be felt beating, and can be readily compressed.
In the above course it lies in the posterior part of the submaxillary triangle, and,
in addition to the structures already mentioned as crossing it, is covered by the
skin, superficial fascia, and platysma, and by one or two submaxillary lymphatic
glands. The vein is separated from the artery by the submaxillary gland, the
posterior belly of the digastric muscle, the stylo-hyoid muscle, and the hypoglossal

nerve.
The facial portion (fig. 334) of the facial artery ascends tortuously forwards
towards the angle of the mouth, passing under the platysma (risorius) and zygomatic
muscles and the supramaxillary and buccal branches of the facial nerve. It here
lies upon the jaw and the buccinator muscle. Thence it courses upwards by the
side of the nose towards the inner canthus of the eye, being covered by the levator
labii superioris, levator labii superioris alæque nasi, and infraorbital branches of
the facial nerve, and lying on the levator anguli oris (sometimes on the levator
LL 2

516
THE ARTERIES
labii superioris, instead of below it) and the infraorbital branches of the fifth
The facial vein takes a much straighter course than the artery, is
separated from it by the zygomatic muscles, and lies to its outer side.
nerve.
FIG. 334.-SCHEME OF THE FACIAL ARTERY.
Orbicularis palpebrarum muscle
Frontal branch of ophthalmic
artery
Nasal branch of ophthalmic
artery
Transverse facial artery
Zygomaticus minor
muscle
Zygomaticus major
muscle
Buccinator muscle
Masseteric branch
Masseter muscle
Stylo-pharyngeus
muscle
Stylo-glossus muscle
Ascending palatine branch
Tonsillar branch
Facial artery
External carotid
artery
Posterior belly of
digastric muscle
Lingual artery
Angular artery
Levator labii superioris
et alæ nasi muscle
Infraorbital artery
Lateralis nasi artery
Levator anguli oris
muscle
Artery of septum
Superior coronary artery
Risorius muscle
Inferior coronary artery
Mental branch of inferior dental
artery
Depressor labii inferioris muscle
Inferior labial artery
Depressor anguli oris muscle
Submental artery
Branches to submaxillary gland
Anterior belly of digastric muscle
Mylo-hyoid muscle
Hyo-glossus muscle
HYPOGLOSSAL NERVE
BRANCHES OF THE FACIAL ARTERY IN THE NECK
The branches of the facial artery in the neck are:-(1) The ascending, or
inferior palatine; (2) the tonsillar; (3) the glandular; (4) the muscular; (5) the
submental.
(1) The ascending, or inferior palatine (figs. 333, 334)-the first branch of the
facial, but often a distinct branch of the external carotid-ascends between the
FACIAL
517
internal and external carotids, and then between the stylo-glossus and stylo-pharyn-
geus muscles, and on reaching the wall of the pharynx is continued upwards between
the superior constrictor and internal pterygoid muscles towards the base of the skull
as high as the levator palati, where it divides into two branches, a palatine and a
tonsillar. One of these branches, the palatine, passes with the levator palati over
the curved upper margin of the superior constrictor to the soft palate, where it is
distributed to the tissues constituting that structure, and anastomoses with its
fellow of the opposite side and with the descending palatine branch of the internal
maxillary, and the ascending pharyngeal, which vessel often to a great extent
supplies the place of this artery. The other branch, the tonsillar, supplies the
tonsil and the Eustachian tube, anastomosing with the tonsillar branch of the facial
and ascending pharyngeal arteries. The ascending palatine artery supplies the
muscles between which it runs on its way to the palate.
(2) The tonsillar branch (fig. 334) ascends between the stylo-glossus and internal
pterygoid muscles to the level of the tonsil, where it perforates the superior con-
strictor muscle of the pharynx, and ends in the tonsil, anastomosing with the tonsillar
branch of the ascending palatine and with the other tonsillar arteries (fig. 333).
It gives branches also to the root of the tongue.
(3) The glandular or submaxillary branches are distributed to the submaxil
lary gland as the artery is passing through or beneath that structure. A small
twig from one of these branches usually supplies Wharton's duct.
(4) The muscular branches are small twigs given off irregularly to the contiguous
muscles, viz. the posterior belly of the digastric, the stylo-hyoid, the stylo-glossus,
and the mylo-hyoid muscles.
(5) The submental branch (fig. 334) comes off from the facial as the latter vessel
lies under cover of the submaxillary gland, and, passing forwards on the mylo-hyoid
muscle between the base of the jaw and the anterior belly of the digastricus,
supplies these structures and the overlying platysma and integuments. It gives
off the following small branches:-(a) muscular, to the muscles between which it
runs; (b) perforating, which passes through the mylo-hyoid to anastomose with
the sublingual; (c) cutaneous, to the integuments covering it; (d) mental, which
turns over the border of the lower jaw near the symphysis, and, after supplying a
branch to the depressor labii inferioris, the levator menti, and the other adjacent
soft tissues forming the chin and lip, anastomoses with the mental branch of the
inferior dental, the inferior labial, and the artery of the opposite side.

Lear

BRANCHES OF THE FACIAL ARTERY ON THE FACE
From the outer or concave side of the artery are given off:-(1) masseteric
branches which ascend over the masseter to anastomose with the masseteric
branch of the internal maxillary artery and the transverse facial artery; and (2)
buccal, which pass upwards over the buccinator and anastomose with the buccal
branch of the internal maxillary, the transverse facial, and the infraorbital arteries.
From the inner or convex side the following larger and named vessels are given
off:-(1) The inferior labial; (2) the inferior coronary; (3) the superior coronary;
(4) the lateralis nasi; and (5) the angular.
(1) The inferior labial artery arises either separately from the facial artery, or
in common with the next branch-the inferior coronary. It courses forwards
beneath the depressor anguli oris, and over the depressor labii inferioris, and, after
supplying the contiguous muscles and integuments, anastomoses below with the
submental, above with the inferior coronary, and between the two with the mental
branch of the inferior dental which escapes from the mental foramen.
(2) The inferior coronary artery arising from the facial a little above the
518
THE ARTERIES

inferior labial, or in common with it, passes forwards beneath the depressor anguli
oris towards the angle of the mouth, thence skirts along the lower lip, between
the mucous membrane and orbicularis oris, about a quarter to half an inch from
the junction of the skin and mucous membrane, and anastomoses with its fellow
of the opposite side. It can readily be felt beating during life by pressing the lip
between finger and thumb. It gives off descending branches which anastomose
with the inferior labial and the mental branch of the inferior dental.
(3) The superior coronary artery, arising from the facial a little higher than the
inferior coronary, passes forwards beneath the zygomaticus major, and then, like
the inferior coronary, courses tortuously along the lower margin of the upper
lip between the orbicularis oris and the mucous membrane about half an inch from
the junction of the mucous membrane and the skin. It is usually larger than
the inferior coronary. The superior coronary anastomoses with its fellow of the
opposite side, and gives off a small artery to the septum-arteria septum narium.
Compression of this vessel will sometimes control hæmorrhage from the nose.
In the operation for hare lip, the pin or suture should be passed sufficiently deep
to transfix the divided coronary artery, or hæmorrhage may continue into the mouth.
Bleeding from either coronary vessel can be readily controlled by the thumb and
forefinger grasping the lip.
(4) The lateral nasal artery (fig. 334) is a small twig or twigs given off from the
facial opposite the ala of the nose. It passes forwards over the ala and lower part of
the nose, supplying the integuments, muscles, and cartilages, and anastomoses with
the artery of the septum, the vessel of the opposite side, and the nasal branches
of the ophthalmic.
9
(5) The angular artery (fig. 334) is the name given to the termination of the
facial artery. It anastomoses at the inner canthus of the eye with the nasal
branch of the ophthalmic. It is accompanied by the anterior descending vein
from the scalp. It lies to the inner side of the lachrymal sac, and supplies
that structure and the lower part of the orbicularis oculi, beneath which a branch
anastomoses with the infraorbital artery. The situation of the artery to the inner
side of the lachrymal sac should be borne in mind in opening a lachrymal abscess.
5. THE OCCIPITAL ARTERY

The occipital artery (fig. 335) is usually a vessel of considerable size. It
comes off from the posterior part of the external carotid opposite the facial, or else
a little higher than that vessel. It then winds upwards and backwards to the
interval between the mastoid process of the temporal bone and transverse process
of the atlas, and, after running horizontally backwards in the occipital groove
on the mastoid portion of the temporal bone, again turns upwards, and ends by
ramifying in the scalp over the back of the skull, extending as far forwards as the
vertex.
The vessel may be divided into three parts-viz. that internal to the sterno-
mastoid muscle; that beneath the sterno-mastoid; and that external to the sterno-
mastoid.
In the first part of its course the occipital artery is covered by the integuments
and fascia, and is more or less overlapped by the posterior belly of the digastric
muscle, the parotid gland, and temporo-maxillary vein. It is crossed by the hypo-
glossal nerve as the latter winds forwards over the carotid vessels to reach the tongue.
It successively crosses in front of the internal carotid artery, the hypoglossal nerve,
the pneumogastric nerve, the internal jugular vein, and the spinal accessory nerve.
In the second part of its course it sinks deeply beneath the digastric muscle
into the interval between the mastoid process of the temporal bone and the trans-


OCCIPITAL
519
verse process of the atlas. It is here covered by the sterno-mastoid, splenius capitis,
and trachelo-mastoid muscles and by the origin of the digastricus; and lies, first
on the rectus capitis lateralis, which separates it from the vertebral artery, then in
the occipital groove on the mastoid portion of the temporal bone, and then on the
insertion of the superior oblique muscle.
r In the third part of its course it enters the triangular interval formed by the
diverging borders of the splenii capitis and the superior curved line of the occipital
bone. Here it lies beneath the integuments and the aponeurosis uniting the occipital
FIG. 335.-SCHEME OF OCCIPITAL AND POSTERIOR AURICULAR ARTERIES.
Anterior branch of.
posterior auricular
Posterior branch of.
posterior auricular
PAROTID GLAND
Sterno-mastoid, cut
Auricular branch of
occipital
Rectus capitis lateralis
SPINAL ACCESSORY
NERVE
Posterior auricular
Internal jugular vein
Facial artery-
HYPOGLOSSAL NERVE
Lingual artery
PNEUMOGASTRIC
NERVE
Superior thyroid
Common carotid
External branch
of occipital
Internal branch
of occipital
Complexus
Princeps cervicis
Superior oblique
Trachelo-mastoid, cut
Splenius capitis, cut
Meningeal branches
Sterno-mastoid branch of
occipital
Internal carotid
Sterno-mastoid
External carotid
Trapezius
attachments of the sterno-mastoid and trapezius, and rests upon the complexus
just before the insertion of that muscle into the occipital bone. In company with
the great occipital nerve, it perforates either this aponeurosis, or less often the
posterior belly of the occipito-frontalis, and follows roughly, but in a tortuous
course, the line of the lambdoid suture lying between the integument and the
cranial aponeurosis. In the scalp it divides into several large branches, which
ramify over the back of the skull and reach as far forwards as the vertex. They
anastomose with the corresponding branches of the opposite side, and with the
posterior auricular, and the superficial temporal arteries.
520
THE ARTERIES
BRANCHES OF THE OCCIPITAL ARTERY
The branches of the occipital artery are:-(1) The sterno-mastoid; (2) the
posterior meningeal; (3) the auricular; (4) the mastoid; (5) the princeps cervicis ;
(6) the communicating; (7) the muscular; and (8) the terminal. The sterno-
mastoid, posterior meningeal, auricular, and princeps cervicis are the four vessels
usually named amongst the above branches.
(1) The sterno-mastoid branch (fig. 335) usually comes off from the occipital
just after its origin from the carotid, and, passing downwards and backwards over
the loop of the hypoglossal nerve, enters the sterno-mastoid muscle in company with
the spinal accessory nerve. At times this artery is a distinct branch of the external
carotid. The hypoglossal nerve then as a rule loops round it instead of round the
occipital.
(2) The posterior meningeal branches (fig. 335), one or more in number, are
long slender vessels which leave the occipital artery as it crosses the internal jugular
vein, and, ascending along that vessel, pass with it through the jugular foramen,
and are distributed to the dura mater lining the posterior fossa of the skull.
(3) The auricular branch ascends over the mastoid process to the back of the
ear, and supplies the pinna and concha. It sometimes takes the place of the
posterior auricular artery (fig. 335).
(4) The mastoid branch is a small twig that passes into the skull through the
mastoid foramen, supplying the dura mater, the diploë, the walls of the lateral
sinus and the mastoid cells.
(5) The princeps cervicis (fig. 335), the largest of the branches of the occipital,
arises from that artery just before it emerges from beneath the splenius, and,
descending for a short distance between the splenius and complexus, divides into a
superficial and a deep branch. The superficial branch perforates the splenius,
supplies branches to the trapezius, and anastomoses with the superficial cervical, a
branch of the transverse cervical artery. The deep branch passes downwards between
the complexus and semispinalis colli, and anastomoses with the deep cervical branch
of the superior intercostal and with branches of the vertebral (fig. 338). The ana-
stomoses between the above-mentioned arteries form important collateral channels
after ligature of the common carotid and subclavian arteries (fig. 330).
(6) The communicating branches run deeply into the triangle formed by the
superior oblique, inferior oblique, and rectus capitis posticus major muscles, and
there anastomose with branches of the vertebral.
(7) Muscular branches throughout the course of the occipital artery are dis-
tributed to the contiguous muscles-viz. in addition to the sterno-mastoid which
receives a named branch, to the digastricus, stylo-hyoid, splenius, trachelo-mastoid,
trapezius, the small muscles forming the suboccipital triangle, and the posterior
belly of the occipito-frontalis.
(8) The terminal or superficial branches (fig. 335), usually two in number, named
from their position internal and external, ramify over the scalp, and have already
been described. The internal branch generally gives off a twig which enters the
parietal foramen (parietal artery).


6. THE POSTERIOR AURICULAR ARTERY
The posterior auricular artery (fig. 335) arises from the posterior part of the
external carotid artery, usually immediately above the posterior belly of the
digastric, about the level of the tip of the styloid process. Occasionally it arises
under cover of the digastric, quite close to, or as a common trunk with, or
as a branch of, the occipital. It courses upwards and backwards in the parotid
POSTERIOR AURICULAR-TEMPORAL
521
gland to the notch between the margin of the external auditory meatus and the
mastoid process, where it divides into two branches, an anterior or auricular, and
a posterior or mastoid. In this course it rests on the styloid process, crosses the
spinal accessory nerve, and is crossed itself by the facial nerve.
BRANCHES OF THE POSTERIOR AURICULAR ARTERY
The branches of the posterior auricular artery are:-(1) The parotid; (2) the
muscular; (3) the stylo-mastoid; (4) the anterior terminal, or auricular; (5) the
posterior terminal, or mastoid (fig. 335).
(1) The parotid branches are distributed to the lower portion of the parotid
gland, and anastomose with the other parotid arteries.
(2) The muscular branches supply the posterior belly of the digastricus, the
stylo-hyoid, and retrahens aurem muscles.
(3) The stylo-mastoid branch comes off from the posterior auricular artery
just before it reaches the notch between the margin of the external auditory meatus
and the mastoid process, and, following the facial nerve upwards, enters the stylo-
mastoid foramen in the temporal bone. In the aqueduct of Fallopius it gives off the
following named twigs :-(a) meatal, to the external auditory meatus; (b) mastoid,
to the mastoid cells and mastoid antrum; (c) stapedic, which runs forwards to
the stapedius muscle; (d) tympanic, which anastomoses with the tympanic branch
of the internal maxillary, forming with it in the foetus a vascular circle around the
membrana tympani; (e) vestibular, to the vestibule and semicircular canals; and
(f) terminal, a small twig which enters the hiatus Fallopii with the great super-
ficial petrosal nerve, and anastomoses with the petrosal branch of the middle
meningeal artery.
(4) The anterior terminal or auricular branch passes upwards behind the ear
and beneath the retrahens aurem, supplying the back of the pinna and neighbour-
ing integuments. It anastomoses with the posterior branch of the superficial tem-
poral artery. The branches to the pinna not only supply the back of that structure,
but some perforate the cartilage, and others turn over its free margin to supply the
front surface; there they anastomose with the anterior auricular branches from
the temporal.
√(5) The posterior terminal, or mastoid or occipital branch, passes upwards and
backwards, crossing the aponeurotic insertion of the sterno-mastoid muscle. It
gives a branch to the posterior belly of the occipito-frontalis, and anastomoses with
the occipital artery.


7. THE TEMPORAL ARTERY
The temporal artery, or superficial temporal artery-the smaller of the two
terminal divisions of the external carotid, though apparently the direct continu-
ation of that vessel arises opposite the neck of the lower jaw and, under cover of
the parotid gland, passes upwards in the interval between the condyle and the
external auditory meatus to the zygoma. Thence it ascends over the posterior root
of that process and the temporal aponeurosis for about an inch and a half to two
inches (4 cm.), and there divides into an anterior and a posterior branch. It
is surrounded by a dense plexus of sympathetic nerves, and is accompanied by the
auriculo-temporal nerve, which lies beneath and generally a little behind it. It is
crossed by the temporo-facial division of the facial nerve, and by the attrahens
aurem muscle. As it crosses the zygoma it can be readily felt pulsating immediately
in front of the ear, and in this situation can be compressed against the bone. It is
here quite superficial, being merely covered by the integuments and the delicate
prolongation from the cervical fascia.
522
THE ARTERIES
d
d
BRANCHES OF THE TEMPORAL ARTERY
The branches of the temporal artery are:-(1) The parotid; (2) the articular;
(3) the masseteric; (4) the auricular, or anterior auricular; (5) the transverse
facial; (6) the middle temporal; (7) the orbital; (8) the anterior terminal; (9) the
posterior terminal.
(1) The parotid branches are small twigs given off in the substance of the
parotid gland to that structure.
人
​(2) The articular branches supply the temporo-maxillary joint.
(3) The masseteric are one or two small branches to the masseter muscle.
(4) The auricular or anterior auricular branches supply the tragus, the pinna,
and the lobule of the ear, and to some extent the external auditory meatus.
(5) The transverse facial is the largest branch of the temporal. It sometimes
arises from the external carotid as a common trunk with the temporal. It is at
first deeply seated in the substance of the parotid gland, but, soon emerging from
under that part of the gland known as the socia parotidis, courses transversely across
the masseter muscle about a finger's breadth below the zygoma. Steno's duct runs
below it, and the infraorbital branches of the facial nerve above it. It supplies the
parotid gland, the masseter muscle, and the skin of the face, and anastomoses with
the infraorbital, the buccal, and the facial arteries.
(6) The middle temporal branch, or middle deep temporal artery (fig. 336),
arises just above the zygoma, and, perforating the temporal aponeurosis and
temporal muscle, ascends on the squamous portion of the temporal bone, and
anastomoses with the posterior deep temporal artery.
(7) The orbital or zygomatico-orbital branch (fig. 336), as it is sometimes called
-at times a branch of the deep temporal-passes forwards along the upper border
of the zygoma in the fat between the superficial and deep layer of the temporal
aponeurosis, and, after giving branches to the orbicularis oculi, sends one or more
twigs into the orbit through the orbital foramina in the malar bone to anastomose
with the lachrymal and palpebral branches of the ophthalmic.
(8) The anterior terminal branch ramifies tortuously in an upward and forward
direction over the front part of the skull. It lies, first between the skin and
temporal fascia, and then between the skin and occipito-frontalis. It supplies
the anterior belly of the occipito-frontalis and the orbicularis oculi muscles, and
anastomoses with the supraorbital, supratrochlear, and frontal branches of the
ophthalmic, and with the corresponding artery of the opposite side. The secondary
branches given off from this vessel to the scalp run from before backwards.
(9) The posterior terminal branch ramifies on the side of the head between
the skin and temporal fascia. Its branches anastomose, in front with the anterior
terminal branch; behind, with the posterior auricular and occipital arteries; and
above, across the vertex of the skull, with the corresponding artery of the opposite
side.


8. THE INTERNAL MAXILLARY ARTERY
The internal maxillary artery (fig. 336) is the larger of the two terminal
divisions of the external carotid. It arises opposite the neck of the jaw in the
substance of the parotid gland, and, passing first between the neck of the jaw
and the spheno-mandibular ligament, and then between the external and internal
pterygoid muscles, sinks deeply into the spheno-maxillary fossa, and there breaks
up into its terminal branches. It is divided into three portions: a maxillary, a
pterygoid, and a spheno-maxillary.
(1) In the first part of its course (the maxillary portion) the artery lies between
the neck of the jaw and the spheno-mandibular ligament, taking a horizontal course

INTERNAL MAXILLARY
523
forwards and inwards parallel to and a little below the auriculo-temporal nerve and
the external pterygoid muscle. It is here surrounded by the deep portion of the
parotid gland, and usually crosses in front of the mandibular (inferior dental) nerve.
(2) In the second part of its course (the pterygoid portion) the artery lies either
between the two pterygoid muscles and the ramus of the jaw, and then turns
upwards over the outer surface of the external pterygoid beneath the temporal
muscle to gain the two heads of the external pterygoid, between which it sinks into
the spheno-maxillary fossa; or it passes behind and internal to the external ptery-
goid, and is covered by that muscle till it reaches the interval between its two
FIG. 336.-SCHEME OF INTERNAL MAXILLARY ARTERY.
Orbital
branch
Palpebral
branch
Nasal branch
Anterior
dental branch
Labial
branch
Posterior
dental branch
Alveolar branch
Incisive branch
Mental branch
Submental branch.
Infraorbital artery and nerve
Spheno-palatine branch
Posterior or descending palatine branch
Naso-palatine branch
Vidian branch
Anterior deep temporal artery
External pterygoid branch
Buccal branch with
portion of buccal nerve
Mylo-hyoidean branch
Posterior deep temporal artery
Small meningeal
artery
Middle meningeal
artery
Temporal artery
Tympanic branch
Deep auricular
branch
Masseteric branch
- External carotid
artery
Internal lateral
ligament
Mandibular
artery and
nerve
Internal pterygoid branch
heads, where it then often forms a projecting loop as it turns into the spheno-
maxillary fossa.
(3) In the third part of its course (the spheno-maxillary portion) the artery lies
in the spheno-maxillary fossa beneath the maxillary division of the fifth nerve, and
in close relationship with Meckel's ganglion, and there breaks up into its terminal
branches.
BRANCHES OF THE INTERNAL MAXILLARY ARTERY
The branches of the internal maxillary artery are as follow:-
(A) From the first part:-(1) The deep auricular; (2) the tympanic; (3) the
middle meningeal; (4) the mandibular (inferior dental); (5) the small meningeal
(sometimes). All these vessels pass through bony or cartilaginous canals.
524
THE ARTERIES
(B) From the second part :-(1) The masseteric; (2) the posterior deep temporal;
(3) the internal pterygoid; (4) the external pterygoid; (5) the buccal; and (6) the
anterior deep temporal. All these branches supply muscles.
(C) From the third part:-(1) The posterior dental, or alveolar; (2) the infra-
orbital; (3) the posterior, or descending palatine; (4) the Vidian; (5) the pterygo-
palatine; and (6) the naso- or spheno-palatine. All these branches pass through
bony canals.
Branches of the First Part of the Internal Maxillary Artery.-(1) The deep
auricular (fig. 336) passes upwards in the substance of the parotid gland behind the
capsule of the temporo-maxillary joint, and, perforating the bony or cartilaginous
wall of the external auditory meatus, supplies the skin of that passage and the
membrana tympani. It at times gives a branch to the joint as it passes behind
the temporo-maxillary capsule.
(2) The tympanic branch, or Glaserian artery, is a long slender vessel, which
runs upwards behind the condyle of the jaw to the Glaserian fissure, through which
it passes to the interior of the tympanum. Here it supplies the lining membrane of
that cavity and the laxator tympani muscle, and anastomoses with the other
tympanic arteries, forming with the tympanic branch of the stylo-mastoid artery a
vascular circle around the membrana tympani. This circle is more distinct in the
fœtus than in the adult.
(3) The middle or great meningeal is the largest branch of the internal maxillary
artery. It comes off from that vessel as it lies between the spheno-mandibular liga-
ment and the ramus of the jaw, and under cover of the external pterygoid passes
directly upwards to the foramen spinosum, through which it enters the interior of the
cranium. In this part of its course it is crossed by the chorda tympani nerve; and
just before it enters the foramen is embraced by the two heads of origin of the
auriculo-temporal nerve (fig. 336).
The trunk of the mandibular division of the fifth nerve, as the latter emerges
through the foramen ovale, lies in front of the artery. As the artery passes upwards
it is surrounded by filaments of the sympathetic nerve, and is accompanied by two
veins which open into the internal maxillary vein. On entering the skull it ramifies
between the bone and dura mater, supplying both structures. It at first ascends
for a short distance in a groove on the greater wing of the sphenoid, and then
divides into two branches, an anterior and posterior.
The anterior branch passes upwards, in the groove on the greater wing of the
sphenoid, on to the parietal bone at its anterior and inferior angle; at this spot
the groove becomes deepened and often bridged over by a thin plate of bone, being
converted for a quarter to half an inch or more into a distinct canal. The situation
of the artery is here indicated on the exterior of the skull by a spot an inch and a
half behind, and about an inch above, the external angular process of the orbit.
The anterior branch is continued along the anterior border of the parietal bone
nearly as far as the superior longitudinal sinus, and gives off in its course, but
especially posteriorly, large branches which ramify in an upward and backward
direction in grooves on the parietal bone (fig. 337).
The posterior branch passes backwards over the squamous portion of the
temporal bone; and thence on to the parietal bone, behind the anterior branch.
This branch and its collaterals extend upwards as far as the longitudinal sinus,
and backwards as far as the lateral sinus.
In addition to its terminal anterior, and terminal posterior branches, the middle
meningeal gives off:-(a) Gasserian branches to the Gasserian ganglion and
Meckel's space. (b) A petrosal branch, which enters the hiatus Fallopii, and
anastomoses with the terminal branch of the stylo-mastoid artery. (c) A tympanic
branch, which enters the canal for the tensor tympani, and supplies that muscle.
(d) An orbital or lachrymal branch, which enters the orbit at the outermost part


INTERNAL MAXILLARY
525
of the sphenoidal fissure, or sometimes through a minute foramen, just external
to that fissure, and anastomoses with the lachrymal branch of the ophthalmic.
(e) Anastomotic or perforating branches which pierce the greater wing of the
sphenoid bone, and anastomose with the deep temporal arteries.
(4) The mandibular (inferior dental) artery (fig. 336), arising from the
internal maxillary as it lies between the spheno-mandibular ligament and neck of
the jaw, courses downwards to the mandibular foramen, which it enters in company
with, and a little behind and external to, the mandibular nerve. It then passes
along the canal in the interior of the bone, giving off branches to the molar, bicuspid,
and canine teeth. On reaching the mental foramen it divides into two branches, the
incisive and the mental. The incisive continues its course in the bone, and supplies
branches to the incisor teeth, and anastomoses with the artery of the opposite side.
OCCIPITAL
POINT
FIG. 337. THE MIDDLE MENINGEAL ARTERY WITHIN THE SKULL.
BREGMA
BASION
OPHRYON
SUB-NASAL
POINT
The mental passes through the mental foramen in company with the mental branch
of the inferior dental nerve, and emerges on the chin under cover of the depressor
labii inferioris. It anastomoses above with the inferior coronary, and below with.
the submental, and also with the inferior labial. Near its origin the artery gives
off (a) a lingual or gustatory branch, which accompanies and supplies the lingual
nerve, and ends in the mucous membrane of the mouth; and, just before it enters
the dental foramen in the lower jaw, (b) a mylo-hyoidean branch, which accompanies
the nerve of that name along the groove in the lower jaw, and, after supplying the
mylo-hyoid muscle, anastomoses with the sublingual and submental arteries.
(5) The small meningeal arises either from the internal maxillary a little in
front of the middle or great meningeal, or as a branch of that vessel. It passes
upwards along the course of the mandibular division of the fifth nerve, and, entering
the skull through the foramen ovale, is distributed to the Gasserian ganglion, and to
the walls of the cavernous sinus and the dura mater in the neighbourhood.
526
THE ARTERIES
Branches of the Second Part of the Internal Maxillary Artery.-The branches
of the second portion of the internal maxillary all supply muscles. They are:-
(1) The masseteric; (2) the posterior deep temporal; (3) the internal pterygoid;
(4) the external pterygoid; (5) the buccal; and (6) the anterior deep temporal.
(1) The masseteric branch comes off from the internal maxillary as the latter
is passing from between the neck of the jaw and the spheno-mandibular ligament.
It is directed outwards along with the masseteric nerve, and, passing through the
sigmoid notch in the lower jaw, supplies the masseter muscle. Some filaments
perforate the muscle and anastomose with the transverse facial and with the
masseteric branches of the facial itself.
(2) The posterior deep temporal arises, as a rule, from the internal maxillary
in common with the masseteric or a little beyond that branch. It passes upwards
beneath the temporal muscle in a slight groove on the anterior margin of the
squamous portion of the temporal bone, supplying the temporal muscle, the
pericranium, and the external layer of the bone. It anastomoses with the
anterior deep temporal and the other temporal arteries.
(3) The internal pterygoid branches are short trunks which pass into and
supply the internal pterygoid muscle.
(4) The external pterygoid branches supply the external pterygoid muscle,
and, like the internal pterygoid branches, are short trunks, and very irregular in
their number, origin, and distribution.
(5) The buccal branch (fig. 336) courses forwards and downwards with the
buccal nerve to the buccinator muscle, lying in close contact with the inner side
and anterior margin of the tendon of the temporal muscle and coronoid process of
the lower jaw. It supplies the buccinator muscle and mucous membrane of the
mouth, and anastomoses with the facial, transverse facial, and infraorbital
arteries.
(6) The anterior deep temporal branch ascends beneath the temporal muscle
in a slight groove on the greater wing of the sphenoid bone. It supplies the
muscle, pericranium, and subjacent bone, and gives off small branches which
pass through minute foramina in the malar bone. Some of these last branches
enter the orbit and anastomose with the lachrymal artery; others emerge on the
face and anastomose with the transverse facial artery.
Branches of the Third Part of the Internal Maxillary Artery.-The branches
of the third part of the internal maxillary artery, like those of the first part, all
pass through bony canals. They are the following:-(1) The posterior dental, or
alveolar; (2) the infraorbital; (3) the posterior, or descending palatine; (4) the
Vidian; (5) the pterygo-palatine; and (6) the naso-palatine, or spheno-palatine.
(1) The posterior dental or alveolar branch arises from the internal maxillary
as the latter is passing into the spheno-maxillary fossa, and descends in a tor-
tuous manner in a groove on the back of the body of the maxilla. It gives off
the following branches :-(a) Antral, which pass through small foramina into the
antrum ; (b) dental, which pass into bony canals to supply the molar and bicuspid
teeth; (c) alveolar, or gingival, which supply the gums; and (d) buccal, which
are distributed to the buccinator muscle.
(2) The infraorbital branch arises from the internal maxillary, generally as
a common trunk with the posterior dental. It passes forwards and a little upwards
through the spheno-maxillary fossa; then forwards in company with the maxillary
division of the fifth nerve, first along the groove, and then through the canal in
the orbital plate of the maxilla; and finally, emerging on the face at the infra-
orbital foramen, under cover of the levator labii superioris proprius, is distributed
to the structures forming the upper lip, the lower eyelid, the lachrymal sac, and the
side of the nose. It anastomoses with the inferior coronary and angular branches
of the facial, with the nasal and lachrymal branches of the ophthalmic, and with the



INTERNAL MAXILLARY
527
transverse facial. It gives off the following small branches :-(a) Orbital, to the
fat of the orbit and to the inferior rectus and inferior oblique muscles; (b) an
anterior dental branch, which passes downwards through a groove in the anterior
wall of the superior maxilla, and supplies branches to the incisor and canine teeth
and the mucous membrane of the antrum; and (c) nasal branches, which pass
through the foramina in the nasal process of the superior maxilla (sutura notha).
(3) The posterior or descending palatine branch descends in the posterior
palatine canal with the posterior palatine branches of Meckel's ganglion. On
emerging on the palate at the posterior palatine foramen, it divides into the following
branches :-(a) An anterior branch, which courses forwards in the muco-periosteum
at the junction of the hard palate with the alveolar process as far as the anterior
palatine foramen, where it anastomoses with the naso-palatine artery; and (b)
posterior branches, which pass backwards and downwards into the soft palate,
contributing to the supply of that structure, and anastomosing with the ascending
palatine artery. After the operation for cleft palate, serious hæmorrhage occasion-
ally occurs from the descending palatine artery. It may be stopped by compressing
the artery by means of a plug inserted in the posterior palatine foramen. The
foramen is situated a little behind, and internal to, the last molar tooth, and almost
immediately in front of the hamular process.
(4) The Vidian artery is a long slender branch which passes backwards
through the Vidian canal in company with the Vidian nerve into the cartilage of
the middle lacerated foramen. It gives off the following branches:-(a) Pharyngeal,
which contributes to the supply of the roof of the pharynx, and anastomoses with
the ascending pharyngeal and pterygo-palatine arteries; (b) Eustachian, which is
distributed to the Eustachian tube; and (c) tympanic, which enters the tympanum,
and anastomoses with the other tympanic arteries.
(5) The pterygo-palatine artery, or pterygo-pharyngeal as it is sometimes
called, a still more slender branch than the Vidian, passes backwards through
the pterygo-palatine foramen with the pharyngeal nerve, a branch of Meckel's
ganglion. It divides into three branches: (a) Pharyngeal, to the roof of the pharynx;
(b) Eustachian, to the Eustachian tube; and (c) sphenoidal, to the sphenoidal cells.
The pterygo-palatine sometimes arises from the spheno-palatine.
(6) The spheno-palatine or naso-palatine artery, the terminal branch of the
internal maxillary, passes with the spheno-palatine branch of Meckel's ganglion
from the spheno-maxillary fossa into the nose through the spheno-palatine foramen.
Crossing the roof of the nose in the muco-periosteum, it passes on to the septum,
and then runs forwards and downwards in a groove on the vomer (under the name
of the naso-palatine, or artery of the septum) towards the anterior palatine
foramen, where it anastomoses with the anterior palatine artery, which enters the
nose through the lateral compartment of that foramen (the canal of Stenson). In
this course it gives off the following branches:-(a) A pharyngeal branch (or descend-
ing pharyngeal branch, as it is sometimes called), which is distributed to the roof
and contiguous portions of the pharynx. (b) A sphenoidal branch, which supplies
the sphenoidal cells. (c) Nasal branches, which ramify over the turbinal bones
and lateral walls of the nose, and give twigs to the ethmoidal and frontal sinuses
and lining membrane of the antrum. (d) Ascending septal branches, which run
upwards and forwards, giving small twigs to the mucous membrane covering the
upper part of the septum, and which pass through the cribriform plate of the
ethmoid, and anastomose with the ethmoidal arteries (perforating or meningeal
branches).



528
THE ARTERIES
THE INTERNAL CAROTID ARTERY
The internal carotid (fig. 338) arises with the external carotid at the bifurcation
of the common carotid, opposite the upper border of the thyroid cartilage, on a
level with the fourth cervical vertebra. It is at first placed a little external to the
external carotid, but as it ascends in the neck the latter vessel becomes more
superficial and in front of it. The internal carotid passes up the neck, in front of
FIG. 338. THE INTERNAL CAROTID ARTERY, AND DEEP BRANCHES OF THE EXTERNAL
CAROTID ARTERY.
(From a dissection in the Hunterian Museum.)
External carotid artery
Temporal artery
Internal maxillary artery
Superior oblique
Transverse facial artery
STENSON'S DUCT
Splenius capitis, cut
Third part of occipital artery
Superior constrictor
Ascending palatine artery
Ascending pharyngeal
artery
External carotid artery,
cut short
Stylo-pharyngeus
Stylo-glossus
Facial artery
LOWER
JAW
Digastricus
Posterior auricular artery
First part of occipital
artery
Princeps cervicis artery
Occipital part of vertebral
artery
Inferior oblique
Complexus
Lingual artery
Semispinalis colli
Complexus
Ascending cervical artery
Deep cervical artery
SUBMAXILLARY GLAND
Superior thyroid artery
Sterno-mastoid, cut
Rectus capitis anticus major
the transverse processes of the upper cervical vertebræ, to the carotid foramen,
thence through the carotid canal in the petrous portion of the temporal bone,
making at first a turn forwards and inwards and then a second turn upwards, and
enters the cranium through the foramen lacerum medium. It then makes a sigmoid
curve on the side of the body of the sphenoid bone, and terminates, after perforating
the dura mater, by dividing opposite the anterior clinoid processes in the fissure of
Sylvius, into the anterior and middle cerebral arteries.
In its course up the neck it often forms one or more curves, especially in old
people. Between the internal and the external carotids, at their angle of divergence,
is situated the intercarotid body, or ganglion intercaroticum.

INTERNAL CAROTID
529
The internal carotid is the continuation upwards of the primitive dorsal aorta,
and supplies the greater part of the brain, the contents of the orbit, and parts of
the internal ear, forehead, and nose. It is divided into three portions:--1. A
cervical; 2. an intraosseous, or petrosal; and 3. an intracranial.
1. THE CERVICAL PORTION

Relations. In the neck the artery is at first comparatively superficial, having
in front of it, as it lies in the superior carotid triangle, the skin, superficial fascia,
platysma and deep fascia, and the overlapping edge of the sterno-mastoid muscle.
Higher up, as it sinks beneath the parotid gland (fig. 329), it becomes deeply placed,
and is crossed by the posterior belly of the digastric and stylo-hyoid muscles, the
hypoglossal nerve, and the occipital and posterior auricular arteries; whilst still
higher it is separated from the external carotid artery, which here gets in front of
it, by the stylo-glossus and stylo-pharyngeus muscles, the glosso-pharyngeal nerve,
the pharyngeal branch of the pneumogastric nerve, and by the stylo-hyoid ligament.
Behind, it lies upon the rectus capitis anticus major, which separates it from the
transverse processes of the three upper cervical vertebræ, on the superior cervical
ganglion of the sympathetic nerve, and on the pneumogastric nerve. Near the
base of the skull, the hypoglossal, pneumogastric, glosso-pharyngeal, and spinal
accessory nerves cross obliquely behind it, separating it at this spot from the internal
jugular vein, which, as the artery is about to enter the carotid canal, also forms one
of its posterior relations.
oimiedingo
On its outer side are the internal jugular vein and pneumogastric nerve.
On its inner side it is in relation with the pharynx, the superior constrictor muscle
separating it from the tonsil. The ascending pharyngeal and ascending palatine
arteries, and at the base of the skull the Eustachian tube and levator palati
muscle are also internal to it.

2. THE INTRAOSSEOUS OR PETROSAL PORTION
The intraosseous portion (fig. 331) is situated in the carotid canal in the
petrous portion of the temporal bone. It is here separated from the walls of the
canal by a prolongation downwards of the dura mater. In this part of its course
it first ascends in front of the tympanum and cochlea of the internal ear; it then
turns forwards and inwards, lying a little internal to and behind the Eustachian
tube, and enters the cranial cavity by turning upwards through the foramen
lacerum medium, lying upon the lingula of the sphenoid bone. In this part of its
course it is accompanied by the ascending branches from the superior cervical
ganglion of the sympathetic. These form a plexus about the artery, but are situated
chiefly on its outer side. It is also surrounded by a number of small veins, which
receive tributaries from the tympanum, and open into the cavernous sinus and
internal jugular vein.

3. THE INTRACRANIAL PORTION
On entering the cranium through the foramen lacerum medium, the internal
carotid first ascends towards the posterior clinoid process, but soon changing its
direction, it curves forwards and slightly downwards by the side of the body of the
sphenoid bone on the inner wall of the cavernous sinus. Here it has the sixth nerve
immediately external to it, and is covered by the lining membrane of the sinus.
Again turning upwards, it pierces the dura mater on the inner side of the anterior
clinoid process, and, passing between the second and third nerves to the anterior
perforated spot at the inner end of the Sylvian fissure, divides into its two terminal
branches, the anterior and middle cerebral. After it has perforated the dura mater,
it is described by some anatomists as a fourth portion-the intracerebral (fig. 387).
M M
530
THE ARTERIES
BRANCHES OF THE INTERNAL CAROTID ARTERY
The cervical portion gives off no branch. The intraosseous portion gives
off:-(1) Tympanic; (2) Vidian. The intracranial portion gives off: -(1)
Arteria receptaculi; (2) pituitary; (3) Gasserian; (4) meningeal; (5) ophthalmic;
(6) posterior communicating; (7) anterior choroid; (8) anterior cerebral; (9)
middle cerebral.
Branches of the Intraosseous Portion.-(1) The tympanic enters the tympanum
through a small foramen in the posterior wall of the carotid canal, and contributes
its quota to the blood-supply of that cavity. It anastomoses with the tympanic
branches of the stylo-mastoid and internal maxillary arteries. (2) A Vidian branch
is also described, and is said to anastomose with the Vidian artery.
Branches of the Intracranial Portion.-As the internal carotid artery lies.
on the inner side of the cavernous sinus, it gives off the following branches:-
(1) Arteria receptaculi, small branches to the walls of the cavernous sinus; (2)
pituitary branches to the pituitary body; (3) Gasserian or ganglionic branches
to the Gasserian ganglion; (4) meningeal or anterior meningeal branches to the
dura mater; these anastomose with anterior branches of the middle meningeal.
(5) THE OPHTHALMIC ARTERY
The ophthalmic artery (fig 339) comes off from the internal carotid imme-
diately below the anterior clinoid process just as the latter vessel is passing through
the dura mater. Entering the orbit through the optic foramen below and external.
to the optic nerve, it at once perforates the sheath of dura mater which is prolonged.
through the optic foramen on both artery and nerve. It then runs in a gentle
curve with its convexity outwards below the optic nerve and external rectus, being
here crossed by the nasal nerve, and turning forwards, inwards, and upwards,
passes over the optic nerve, round which it thus forms a loop (fig. 339) to the inner
side of the orbit. Thence it runs obliquely beneath the superior rectus in front of
the nasal nerve under the lower border of the superior oblique, but above the
internal rectus, and continues its course under the pulley for the superior oblique
and reflected tendon of that muscle to the internal angular process of the orbit,,
where it divides into the frontal and nasal branches.

BRANCHES OF THE OPHTHALMIC ARTERY
The branches of the ophthalmic artery are:-(a) the lachrymal; (b) the supra-
orbital; (c) the central artery of the retina; (d) the muscular; (e) the ciliary; (f)
the posterior ethmoidal; (g) the anterior ethmoidal; (h) the palpebral; (i) the
frontal; and (k) the nasal.
(a) THE LACHRYMAL ARTERY
The lachrymal artery is usually the first and at times the largest branch of
the ophthalmic. It arises between the superior and external rectus on the outer
side of the optic nerve from the ophthalmic soon after that vessel has entered the
orbit. At times it is given off from the ophthalmic outside the orbit, and then
usually passes into that cavity through the sphenoidal fissure. It runs forwards.
along the outer wall of the orbit with the lachrymal nerve above the upper border
of the external rectus to the lachrymal gland, which it supplies. In this course it
furnishes the following branches :-(i) Recurrent lachrymal, one or more branches.
which pass backwards through the sphenoidal fissure, and anastomoses with the
lachrymal branch of the middle meningeal artery. This anastomosis is some-


BRANCHES OF OPHTHALMIC
531
times of large size, and takes the chief share in the formation of the lachrymal
artery. (ii) Muscular branches, distributed chiefly to the external rectus. (iii)
Malar branches-small twigs, which pass through the malar canals, and anasto-
mose with the orbital branch of the middle temporal, and with the transverse
facial on the cheek. (iv) Palpebral branches, which are distributed to the upper and
lower eyelids and to the conjunctiva. (v) Ciliary. See CILIARY ARTERIES, page 532.
(b) THE SUPRAORBITAL ARTERY
The supraorbital artery usually arises from the ophthalmic as the latter vessel
is about to cross over the optic nerve. Passing upwards to the inner side of the
superior rectus and levator palpebræ, it runs along the upper surface of the latter
muscle with the frontal nerve, but beneath the periosteum to the supraorbital
notch. On emerging on the forehead beneath the orbicularis palpebrarum, it divides
FIG. 339.-THE OPHTHALMIC ARTERY AND VEIN.
Supraorbital artery
LACHRYMAL GLAND
Superior rectus
EYEBALL
External rectus
Commencement of superior
ophthalmic vein
Reflected tendon of
superior oblique
Ophthalmic artery
Anterior ethmoidal artery
Lachrymal artery
Superior rectus, cut
Inferior ophthalmic vein-
Superior ophthalmic vein
OPTIC NERVE-
Common ophthalmic vein-
Posterior ethmoidal artery
Ciliary arteries
Levator palpebræ, cut
Ligament of Zinn
Ophthalmic artery
OPTIC COMMISSURE
Internal carotid artery
into a superficial and deep branch; the former ramifies between the skin and
occipito-frontalis, the latter between the occipito-frontalis and the pericranium.
Both branches anastomose with the anterior branches of the superficial temporal,
the angular branch of the facial, and the transverse facial artery. The branches
of the supraorbital are:-(i) Periosteal, to the periosteum of the roof of the orbit;
(ii) muscular, to the levator palpebræ and superior rectus; (iii) diploic, given
off as the artery is passing through the supraorbital notch to the diploë and
frontal sinuses; (iv) trochlear, to the pulley of the superior oblique; (v) palpebral,
to the upper eyelid.
THE CENTRAL ARTERY OF THE RETINA
The arteria centralis retinæ, a small but constant branch, comes off from
the ophthalmic close to the optic foramen, and, perforating the optic nerve about a
MM 2
532
THE ARTERIES
quarter of an inch behind the globe, runs forwards in the substance of the nerve to
the eyeball supplying the retina. Its further description is given in the ANATOMY
OF THE EYE.
(d) THE MUSCULAR BRANCHES
The muscular branches are very variable in their origin and distribution.
They may be roughly divided into superior and inferior sets. The superior or
smaller set supply the superior oblique, the levator palpebræ, and superior rectus.
The inferior pass forward between the optic nerve and the inferior rectus, supply-
ing that muscle, the internal rectus, and the inferior oblique. From the muscular
branches are given off the anterior ciliary arteries. (See CILIARY ARTERIES.)
(e) THE CILIARY ARTERIES
The ciliary arteries are divided into three sets:-The short posterior, the long
posterior, and the anterior. (i) The short posterior, five to six in number, come
off chiefly from the ophthalmic as it is crossing the optic nerve. They run forward
about the nerve, dividing into twelve or fifteen small vessels, which perforate the
sclerotic around the entrance of the optic nerve, and are distributed to the choroid
coat. (ii) The long posterior ciliary arteries, usually two in number, come off
from the ophthalmic on either side of the optic nerve, and run forward with the
short ciliary to the sclerotic. On piercing the sclerotic, they course forwards
between that coat and the choroid to the ciliary processes and iris. Their further
distribution is given under the ANATOMY OF THE EYE. (iii) The anterior ciliary
are derived from the muscular branches and from the lachrymal. They run to
the globe along the tendons of the recti, forming a zone of radiating vessels
beneath the conjunctiva. They perforate the sclerotic about a quarter of an inch
(6 mm.) behind the cornea, and supply the iris and ciliary processes. It is these
vessels that are enlarged and congested in iritis, forming the circumcorneal zone
of redness so characteristic of that disease.
(f) THE POSTERIOR ETHMOIDAL ARTERY
The posterior ethmoidal runs inwards between the superior oblique and internal
rectus, and, leaving the orbit by the posterior ethmoidal canal, enters the posterior
ethmoidal cells, whence it passes through a transverse slit-like aperture between
the sphenoid bone and cribriform plate of the ethmoid bone into the cranium. It
gives off (i) ethmoidal branches to the posterior ethmoidal cells; (ii) meningeal
branches to the dura mater lining the cribriform plate; and (iii) nasal branches,
which pass through the cribriform plate to the superior meatus and upper spongy
bones of the nose, and anastomose with the nasal branches of the spheno-palatine
artery.
(g) THE ANTERIOR ETHMOIDAL ARTERY
The anterior ethmoidal (figs. 339, 387), a larger branch than the posterior
ethmoidal, arises in front of the latter, passes inwards between the superior
oblique and internal rectus, and, leaving the orbit through the anterior ethmoidal
canal, in company with the nasal nerve, enters the cranial cavity. After running
a short distance beneath the dura mater on the cribriform plate of the ethmoid
bone, it passes into the nose through the horizontal slit-like aperture by the side of
the crista galli. Its terminal branch passes along the groove on the under surface
of the nasal bone, and emerges on the nose between the bone and lateral cartilage,
terminating in the skin of that organ. It gives off the following branches in its
-(i) Ethmoidal, to the anterior ethmoidal cells; (ii) meningeal, to the dura


POSTERIOR COMMUNICATING-ANTERIOR CHOROID
533
mater of the anterior fossa; (iii) nasal, to the middle meatus and anterior part of
the nose; (iv) frontal, to the frontal sinuses; (v) cutaneous, or terminal, to the skin
of the nose.
(h) THE PALPEBRAL ARTERIES
The palpebral branches arise either separately or by a common trunk from
the ophthalmic artery opposite the pulley for the superior oblique, just as the latter
vessel is about to divide into its terminal branches. They pass, one above and
one below the internal tarsal ligament or tendo oculi, and then skirt along the
upper and lower eyelids respectively, near the free margin between the tarsal
cartilages and the orbicularis muscle, and form a superior and inferior palpebral
arch by anastomosing with the palpebral branches of the lachrymal. The upper
also anastomoses with the supraorbital artery and orbital branch of the temporal
artery; the lower with the infraorbital, the angular branch of the facial, and the
transverse facial arteries. A branch from the lower palpebral passes with the nasal
duct as far as the inferior meatus. Small twigs are also given to the caruncle
and conjunctiva.
(i) THE FRONTAL BRANCH
The frontal branch, the upper of the terminal branches of the ophthalmic,
pierces the tarsal membrane at the inner angle of the orbit, passes upwards over
the frontal bone, supplies the structures in its neighbourhood, and anastomoses with
its fellow of the opposite side, with the supraorbital, and with the anterior division
of the superficial temporal artery.

(k) THE NASAL BRANCH
The nasal, the lower of the terminal branches of the ophthalmic, leaves the
orbit at the inner canthus by perforating the tarsal membrane above the tendo
oculi. It then descends along the dorsum of the nose, beneath the integuments;
and anastomoses with the angular and lateral nasal branches of the facial. It gives
off a lachrymal branch as it crosses the lachrymal sac, and a transverse nasal
branch as it crosses the root of the nose; the latter vessel anastomoses with its
fellow of the opposite side.
(6) THE POSTERIOR COMMUNICATING ARTERY
The posterior communicating artery (fig. 340) is given off from the internal
carotid just before the division of that vessel into the anterior and middle cerebral
arteries; occasionally it arises from the middle cerebral itself. It is as a rule a
slender vessel which runs backwards over the optic tract and crus cerebri along the
side of the uncinate convolution to join the posterior cerebral. At times, however,
it is of considerable size, and contributes chiefly to form the posterior cerebral, the
portion of the latter vessel between the basilar and posterior communicating
being then as a rule reduced to a mere rudiment. It gives off the following
branches :-(a) the uncinate, to the convolution of that name; and (b) the middle
thalamic, to the optic thalamus.
(7) THE ANTERIOR CHOROID ARTERY
The anterior choroid is a small but constant vessel, which arises as a rule
from the back part of the internal carotid just external to the origin of the
posterior communicating, It passes backwards on the optic tract and the crus
cerebri, at first lying parallel and a little external to the posterior communicating
534
THE ARTERIES
artery, and then, turning slightly outwards, dips under the edge of the uncinate
convolution, and, entering the transverse fissure at the lower end of the descending
cornu of the lateral ventricle, ends in the choroid plexus and supplies the hippo-
campus major and corpus fimbriatum.
(8) THE ANTERIOR CEREBRAL ARTERY
The anterior cerebral artery (fig. 340)-one of the terminal branches into
which the internal carotid divides in the fissure of Sylvius-passes at first forwards
and inwards across the anterior perforated space between the olfactory and optic
nerves to the longitudinal fissure where it approaches its fellow of the opposite side,
and communicates with it by a short transverse trunk, about two lines long, known
as the anterior communicating artery. Onwards from this spot it runs side by
side with its fellow in the longitudinal fissure round the genu of the corpus
callosum; then, turning backwards, it continues along the upper surface of that
commissure, and, after giving off large branches to the frontal and parietal lobules,
anastomoses with the posterior cerebral artery.
The branches of the anterior cerebral are:-(a) Communicating; (b) ganglionic,
or central; (c) commissural; (d) hemispheral, or cortical.
(a) Communicating.-The anterior communicating is a transverse trunk about
two lines in length, connecting the right and left anterior cerebral arteries. It lies
immediately in front of the optic commissure across the lamina cinerea. It
gives off some of the antero-median branches which pass from the anterior cerebral
to the fore end of the caudate nucleus. Sometimes the anterior cerebral arteries,
instead of communicating by a transverse trunk, coalesce for a short distance and
then again divide.
(b) Ganglionic, or central.-The antero-median group, together with the antero-
median branches of the anterior communicating, pass through the lamina cinerea
and supply the fore end of the caudate nucleus.
(c) Commissural.--These supply the corpus callosum.
(d) The hemispheral or cortical branches.-(i) The orbital, three or four in
number, supply the inferior surface of the first frontal convolution, and give off
small twigs to the olfactory bulb. (ii) The margino-frontal arise from the artery
as it lies on the corpus callosum, and, after supplying the marginal convolution,
pass on to the convex surface of the hemisphere and further supply the first and
second frontal convolutions and the upper part of the ascending frontal convolution.
(iii) The calloso-marginal supplies the callosal convolution and the upper part
of the marginal convolution. (iv) The quadrate is a branch to the convolution of
that name.

(9) THE MIDDLE CEREBRAL ARTERY
The middle cerebral artery (fig. 340)-the larger of the two terminal divisions
of the internal carotid-passes obliquely upwards and outwards into the fissure of
Sylvius, and opposite the insula or island of Reil divides into its hemispheral or
cortical branches.
The branches of the middle cerebral are:-(a) Ganglionic, or central; and (b)
hemispheral, or cortical.
(a) Ganglionic, or central.-(i) The caudate, two or three small branches, arise
from the inner aspect of the artery and pass through the inner part of the floor
of the fissure of Sylvius to the head of the caudate nucleus. (ii) The antero-
lateral are numerous small arteries, which pass through the anterior perforated
space and supply the caudate nucleus (except its head), the internal capsule, and part
of the optic thalamus. (iii) The lenticulo-striate, a larger branch of the antero-


MIDDLE CEREBRAL-CIRCLE OF WILLIS
535
lateral set, passes through a separate hole in the outer part of the anterior perforated
space, runs upwards between the lenticular nucleus (which it supplies) and the
external capsule, perforates the internal capsule, and terminates in the caudate
nucleus. It has been so frequently found ruptured, that it is called by Charcot the
* artery of cerebral hæmorrhage.'
(b) The hemispheral or cortical branches come off from the middle cerebral
opposite the insula. They are four in number:-(i) The inferior, or orbito-frontal,
to the inferior frontal convolutions. (ii) The ascending frontal, to the lower part
of the ascending frontal convolution, the upper part being supplied by the margino-
frontal, a branch of the anterior cerebral. (iii) The parietal, to the whole of the
ascending parietal and the adjacent part of the inferior parietal convolution.
(iv) The parieto-temporal, to the convolutions around the posterior limb of the
fissure of Sylvius-viz. the supra-marginal, the angular, and the posterior part of
the inferior parietal above, and the first and the greater part of the second and
third temporal below.
FIG. 340.-THE ARTERIES OF THE BRAIN.
(From a preparation in the Museum of St. Bartholomew's Hospital.)
Anterior cerebral
artery
Middle cerebral
artery
Internal carotid
artery
Postero-median
perforating
Posterior cerebral
artery
Superior
cerebellar artery
Anterior inferior
cerebellar artery
Vertebral artery
Posterior inferior
cerebellar artery
Anterior com-
municating
artery
Antero-lateral
perforating
Anterior
choroid
Posterior
communicating
artery
Posterior choroid
Basilar artery
Crus cerebelli,
cut
Anterior spinal
artery
THE CIRCLE OF WILLIS
The anastomosis of the branches of the internal carotid and vertebral arteries
at the base of the brain is known as the circle of Willis (fig. 340). This so-
called circle, which has really the form of a heptagon, is formed, in front, by the
anterior communicating artery uniting the anterior cerebral arteries of opposite sides;
laterally, by the trunk of the internal carotid and the posterior communicating
arteries stretching between it and the posterior cerebral; behind, by the two posterior
cerebrals diverging from the bifurcation of the basilar artery (page 543). This free
anastomosis between the two internal carotid and the two vertebral arteries serves
536
THE ARTERIES
to equalise the flow of blood to the various portions of the brain; and, should one
or more of the arteries entering into the formation of the circle be temporarily or
permanently obstructed, it ensures a flow of blood to the otherwise deprived part
through some of the collateral arteries. Thus, if one carotid or one vertebral is
obstructed, the parts supplied by that vessel receive their blood through the circle
from the remaining pervious vessels. Indeed, one vertebral artery alone has been
found equal to the task of carrying sufficient blood for the supply of the brain
after ligature of both the carotids and the other vertebral artery. Further, the circle
of Willis is the only medium of communication between the ganglionic or central
and the hemispheral or cortical branches of the cerebral arteries, and between the
various ganglionic branches themselves. The ganglionic and the cortical branches
form separate and distinct systems, and do not anastomose with each other; and
the ganglionic, moreover, are so-called end-vessels, and do not anastomose with the
neighbouring ganglionic branches.
THE SUBCLAVIAN ARTERY
The subclavian artery on the right side arises at the bifurcation of the innomi-
nate behind the right sterno-clavicular articulation. On the left side it arises from
the arch of the aorta, and as far as the inner border of the scalenus anticus is
situated deeply in the chest. The first portion of the left subclavian artery is
described separately.
Beyond the inner border of the scalenus anticus the artery has the same rela-
tions on both sides. It courses from this point beneath the clavicle in a slight
curve across the root of the neck to the outer border of the first rib, there to end
in the axillary artery. Thus the course of the artery in the neck will be indicated
by a line drawn from the sterno-clavicular joint in a curve with its convexity upwards
to the middle of the clavicle. The height the artery rises in the neck varies. It is
perhaps most commonly about half an inch above the clavicle. If the curved line
above mentioned is drawn to represent part of the circumference of a circle having
its centre at a point on the lower margin of the clavicle an inch and a half from
the sternal end of that bone, the line of the artery will be sufficiently well indicated
for all practical purposes. In its course the artery arches over the dome of the
pleura and gains the groove on the upper surface of the first rib by passing between
the scalenus anticus and medius muscles. The artery is accompanied by the sub-
clavian vein, the latter vessel lying in front of the scalenus anticus, anterior to the
artery, and on a slightly lower plane.
The subclavian artery is divided into three portions-as it lies internal to,
behind, or external to, the scalenus anticus muscle.
THE FIRST OR THORACIC PORTION OF THE LEFT
SUBCLAVIAN ARTERY

The left subclavian artery (fig. 328) arises from the termination of the transverse
portion of the arch of the aorta. The first part of the left subclavian is conse-
quently longer than the first part of the right, which arises at the bifurcation of
the innominate opposite the right sterno-clavicular joint. The artery at its origin
is situated deeply in the thorax, and as it arises from the aorta is on a plane pos-
terior to and a little to the left of the thoracic portion of the left common carotid.
It first ascends almost vertically out of the chest, and at the root of the neck

RIGHT AND LEFT SUBCLAVIAN
537
curves outwards over the apex of the left pleura and lung to the interval between
the anterior and middle scalene muscles. Beyond the inner border of the scalenus
anticus-that is, in the second and third portions of its course-its relations are
similar to those of the right subclavian artery.
-
Relations. In front it is covered by the left pleura and lung, whilst more super-
ficial are the sterno-thyroid, sterno-hyoid, and sterno-mastoid muscles. It is crossed
a little above its origin by the left innominate vein, and higher in the neck near the
scalenus anticus by the internal jugular, vertebral, and subclavian veins. The
phrenic nerve crosses the artery immediately internal to the scalenus anticus, and
then descends parallel to it but on an anterior plane to cross the arch of the aorta.
The pneumogastric nerve descends parallel to the artery between it and the left
common carotid, coming into contact with its anterior surface just before crossing the
arch of the aorta. The left cervical cardiac nerves of the sympathetic also descend
in front of it on their way to the cardiac plexus. The left common carotid is situated
anteriorly and to its right. The thoracic duct arches over the artery just internal
to the scalenus anticus, to empty its contents into the confluence of the internal
jugular and subclavian veins (fig. 360).
Behind and somewhat internal to it are the oesophagus, thoracic duct, inferior
cervical ganglion of the sympathetic, longus colli muscle, and vertebral column. To
some extent it is overlapped posteriorly by the left pleura and lung (fig. 328).
On its right side are the trachea and the recurrent laryngeal nerve, and, higher
up, the œsophagus and thoracic duct.
On its left side are the left pleura and lung.
The chief variations in the origin of the left subclavian artery are given under VARIATIONS
OF THE ARCH OF THE AORTA (page 501).

THE FIRST PORTION OF THE RIGHT SUBCLAVIAN ARTERY
The first portion of the right subclavian artery extends from its origin at the
bifurcation of the innominate, behind the upper margin of the right sterno-clavicular
joint, upwards and outwards in a gentle curve over the apex of the right lung and
pleura to the inner border of the scalenus anticus. It measures about one inch and
a quarter in length (3 cm.). In this course it ascends in the neck a variable distance
above the clavicle, but is so deeply placed, so surrounded by important structures,
and gives off so many large branches, that it is now seldom or never selected for the
application of a ligature.
Relations. In front it is covered by the integuments, the superficial fascia, the
platysma, the anterior layer of the deep fascia, the clavicular origin of the sterno-
mastoid, the sterno-hyoid and sterno-thyroid muscles, and the deep cervical fascia.
It is crossed by the commencement of the innominate, by the internal jugular, and
by the vertebral veins; and from within outwards by the pneumogastric and phrenic
nerves, and the superior cardiac branches of the sympathetic nerve. A loop of the
sympathetic nerve itself also crosses the artery, and forms with the trunk of the
sympathetic a ring around the vessel known as the annulus of Vieussens.
Behind, but separated from the artery by a cellular interval, are the longus colli
muscle, the transverse process of the seventh cervical or first thoracic vertebra, the
main chain of the sympathetic nerve, the inferior cardiac nerves, the recurrent
laryngeal nerve, and the apex of the right lung and pleura.
Below, it is in contact with the pleura and lung and the loop of the recurrent
laryngeal nerve, which winds round the artery from the pneumogastric and ascends
behind it to the larynx. The subclavian vein is below the artery and on an anterior
plane.
Branches. The vertebral, internal mammary, and thyroid axis arise from this
part of the vessel.

538
THE ARTERIES
THE SECOND PORTION OF THE SUBCLAVIAN ARTERY
The second portion of the subclavian artery lies behind the scalenus anticus
muscle. It measures about three-quarters of an inch in length (2 cm.), and here
reaches highest in the neck. The subclavian vein is separated from the artery
by the scalenus anticus, and lies on a lower and anterior plane.
Relations. In front it is covered by the skin, superficial fascia, platysma,
anterior layer of deep fascia, the clavicular origin of the sterno-mastoid, deep layer
of deep fascia, and by the scalenus anticus. The phrenic nerve-which, in conse-
quence of its oblique course downwards and inwards, crosses a portion of both the
first and second part of the subclavian-is separated from the second portion by
the scalenus anticus muscle.
Behind the artery are the apex of the pleura and lung, and a portion of the
scalenus medius.
Above is the brachial plexus.
Below are the pleura and lung.
One branch only-the superior intercostal-is, as a rule, given off from this
portion of the subclavian.
FIG. 341.-THE SUBCLAVIAN ARTERY.
Scalenus medius
Scalenus anticus and
on it phrenic nerve
Transverse cervical·
artery
Suprascapular artery
Subclavian artery
CORD OF BRACHIAL
PLEXUS, GIVING OFF
MUSCULO-CUTANEOUS
AND OUTER HEAD OF
MEDIAN NERVES
Axillary artery
MUSCULO-SPIRAL
NERVE
Axillary artery
Subscapular and two circumflex arteries
Thyroid axis
Internal jugular
vein
Right common
carotid artery
Vagus
Commencement of
innominate vein
THE THIRD PORTION OF THE SUBCLAVIAN ARTERY
The third portion of the subclavian artery extends from the outer margin of
the scalenus anticus muscle, downwards and outwards to the outer border of the
first rib. It is more superficial than either the first or second portions; it is in rela-
tion with less important structures, and as a rule gives off no branch, and for these
reasons is the part selected when practicable for the application of a ligature. It is

SUBCLAVIAN
539
the longest of the three portions of the subclavian artery, and lies in a triangle-the
subclavian triangle-bounded by the sterno-mastoid, the omo-hyoid, and the clavicle.
Relations. In front it is covered by the skin, superficial fascia, platysma,
clavicular branches of the descending portion of the cervical plexus of nerves;
anterior layer of deep fascia which descends from the omo-hyoid to the clavicle;
and the posterior layer of deep fascia which descends from the omo-hyoid to the
first rib and is prolonged inwards over the scalenus anticus and phrenic nerve.
Between the two layers of fascia is a variable amount of cellular tissue and fat, and
running in this is the suprascapular artery. The subclavian is crossed by this
artery unless the arm is drawn well downwards. Hence one of the reasons
for depressing the shoulder, and thus avoiding the suprascapular artery, in the
operation of ligaturing the subclavian. Close to the outer margin of the sterno-
mastoid, the external jugular vein pierces the fascia, and crosses the subclavian
artery to open into the subclavian vein. As this vein lies between the two layers of
fascia, it receives on its external side the suprascapular, transverse cervical, and
other veins of the neck, which together form a plexus of large veins in front of the
artery. The nerve to the subclavius, and when present the accessory branch from
this nerve to the phrenic, also here cross in front of the artery. In very muscular
subjects the sterno-mastoid may extend further outwards along the clavicle than
usual, and in such a case will form one of the coverings of the artery.
Behind, the artery is in contact with the scalenus medius, and with the cord of
the brachial plexus formed by the union of the eighth cervical and first dorsal nerve.
Below, the artery rests in the posterior of the two grooves on the upper surface
of the first rib.
Above is the brachial plexus of nerves and the posterior belly of the omo-hyoid
muscle. The cord formed by the fifth and sixth cervical nerves is also above the
artery, but on a somewhat anterior plane. It is close to the vessel, and has been
mistaken for the artery in the application of a ligature.
As a rule there is no branch given off from the third portion of the subclavian.
At times, however, the suprascapular (fig. 329) or the posterior scapular artery may
arise from the third portion of the subclavian, instead of from the thyroid axis and
from the transverse cervical respectively as here described.
Chief Variations in the Subclavian Artery
(A) The right subclavian artery may arise directly from the arch of the aorta, and
then come off as the first, second, third or fourth branch of that vessel. When it
arises as the first branch, it takes the place usually occupied by the innominate; when it
arises as the last branch, it courses behind the trachea and oesophagus to gain the groove on
the first rib. As the second or third branch of the aortic arch it is very rare; in both
instances it then runs behind the right common carotid. The explanation of the right
subclavian arising as the last branch of the arch of the aorta, is that the right aortic arch
has remained pervious, whilst the normal root of the subclavian artery has become
obliterated. An arteria aberrans, given off from the right subclavian or from the superior
intercostal, can generally be traced to the third thoracic vertebra behind the oesophagus, and
in a number of such cases can be followed across the spine to anastomose with a branch of
the thoracic aorta given off below the ductus arteriosus. It is the enlargement of this
anastomosis-which is itself the remains of what was the primitive right dorsal aorta in
the embryo-that gives rise to the abnormality in question. The inferior laryngeal nerve
in such cases, in consequence of the right fourth arch which forms the first portion of
the subclavian being obliterated, follows a direct course to the larynx instead of winding
recurrently round the subclavian artery.
(B) The right subclavian may arise higher or lower in the neck than usual, according
as the innominate divides above or below the normal situation.
(C) It may perforate the scalenus anticus or pass in front of that muscle.
(D) It may ascend as high as an inch and a half above the clavicle, or remain below
the level of that bone.
(E) The third part of the artery may be covered by the trapezius or sterno-mastoid, or
by a clavicular origin of the omo-hyoid.
(F) The subclavian vein may accompany the artery behind the scalenus anticus.

540
THE ARTERIES
BRANCHES OF THE SUBCLAVIAN ARTERY
From the first portion of the subclavian artery are given off: from the upper and
back part and about three-quarters of an inch (2 cm.) from its origin, the vertebral;
a little further outwards, from the front part, the thyroid axis; and from the lower
part-usually opposite the thyroid axis, or else between the thyroid axis and the
vertebral-the internal mammary.
From the second portion arises, from the back of the vessel, the superior inter-
costal.
The third portion, as a rule, gives off no branch.
BRANCHES OF THE FIRST PART OF THE SUBCLAVIAN ARTERY
THE VERTEBRAL ARTERY
The vertebral artery, the first and largest branch, arises from the upper and
posterior part of the first portion of the subclavian, on the right side about
three-quarters of an inch (2 cm.) from the origin of the latter vessel from the
innominate, on the left side, from the most prominent part of the arch of the sub-
clavian, close to the inner edge of the scalenus anticus muscle. It first ascends to
the foramen in the costo-transverse process of the sixth cervical vertebra, and, having
passed through that foramen and those of the next succeeding cervical vertebræ as
high as the axis, it turns outwards, and then upwards to reach the foramen in the
transverse process of the atlas; after passing through that foramen it turns back-
wards behind the articular process lying in the groove on the posterior arch of the
atlas. It next pierces the posterior occipito-atloid ligament and the dura mater, and
enters the cranium through the foramen magnum. Here it passes upwards, at first
lying by the side of the medulla, then in front of that structure, and terminates at the
lower portion of the pons by inosculating with the vertebral of the opposite side to
form the basilar.
The vertebral artery may be divided for purposes of description into four parts:
the first, or cervical, extending from its origin to the transverse process of the sixth
cervical vertebra; the second, or vertebral, situated in the intervertebral foramina;
the third, or occipital, contained in the suboccipital triangle; and the fourth, or
intracranial, within the cranium.
The first or cervical portion.-The artery here lies between the scalenus
anticus and longus colli muscles. In front it is covered by the vertebral and internal
jugular veins, and is crossed by the inferior thyroid artery; and on the left side, in
addition, by the thoracic duct, which runs over it from within outwards. Behind,
the artery lies on the transverse process of the seventh cervical vertebra and the
sympathetic nerve. To its inner side is the longus colli. To its outer side is the
scalenus anticus. It gives off as a rule no branch in this part of its course. Occa-
sionally, however, a small branch passes into the foramen of the transverse process
of the seventh cervical vertebra.
The second or vertebral portion.-As the artery passes through the inter-
vertebral foramina, it is surrounded by a plexus of veins and by branches of the
sympathetic nerve. The cervical nerves lie behind it. Between the transverse
processes it is in contact with the intertransverse muscles.
The third or occipital portion. The artery here lies in the suboccipital triangle,
bounded by the superior oblique, inferior oblique, and rectus capitis posticus major
muscles. As it winds round the groove on the atlas, it has the rectus capitis lateralis,
the articular process, and the occipito-atloid ligament in front of it; the superior


VERTEBRAL
541
oblique and the rectus capitis posticus major and the complexus behind it. Sepa-
rating it from the arch of the atlas, is the first cervical or suboccipital nerve.
The fourth or intracranial portion extends from the aperture in the dura mater
to the lower border of the pons, where it unites with its fellow to form the basilar
artery. It here winds round from the side to the front of the medulla, lying in the
vertebral groove on the basilar process of the occipital bone. In this course it passes
beneath the first process of the ligamentum dentatum, and between the hypoglossal
nerve in front, and the anterior roots of the suboccipital nerve behind.
FIG. 342.-SCHEME OF THE VERTEBRAL ARTERY.
The internal jugular and vertebral veins are hooked aside to expose the artery.
Right posterior cerebral
artery
Left posterior cerebral
artery
Basilar artery
Intracranial portion of vertebral
artery
Rectus capitis lateralis muscle
FIRST CERVICAL NERVE
Commencement of vertebral vein
Occipital portion of vertebral
artery
SECOND CERVICAL NERVE
Vertebral plexus of veins
THIRD CERVICAL NERVE
"Vertebral portion of vertebral
artery
FOURTH CERVICAL NERVE
Vertebral plexus of veins
FIFTH CERVICAL NERVE
Arteria princeps cervicis
Semispinalis colli muscle
SIXTH CERVICAL NERVE
Inferior thyroid artery
Longus colli muscle
Cervical portion of vertebral artery
Internal jugular vein
Vertebral vein
Subclavian artery
Deep cervical artery
Scalenus anticus muscle
Thyroid axis
Subclavian vein
Chief Variations of the Vertebral Artery
(A) The right vertebral artery may arise from the first part of the subclavian, either
nearer to the innominate, or nearer to the anterior scalene muscle than normal.
(B) It may come off from the arch of the aorta direct. (See VARIATIONS IN THE CHIEF
BRANCHES OF THE ARCH OF THE AORTA.)
(C) It may arise from the right common carotid when the right subclavian is given off
from the aorta beyond the left subclavian.
(D) It may pass behind the oesophagus.
(E) The left vertebral artery may also arise from the arch of the aorta direct, or from
the left common carotid. (See VARIATIONS IN THE CHIEF BRANCHES OF THE AORTA.)
(F) Either vertebral may enter the foramen in the seventh cervical vertebra, or in that
of the fifth, fourth, third, or second. When entering one of the higher vertebral foramina,
it may lie behind the common carotid and cause some embarrassment in the ligature of
the latter vessel.
(G) Either vertebral may give off the inferior thyroid, superior intercostal, deep
cervical, or occipital artery.
(H) One or other artery may be much increased or diminished in size.
542
THE ARTERIES
BRANCHES OF THE VERTEBRAL ARTERY
A. Cervical portion.-No branch.
B. Vertebral portion.-1. Lateral spinal; 2. muscular.
C. Occipital portion.-1. Muscular; 2. anastomotic.
D. Cranial portion.-1. Posterior meningeal; 2. posterior spinal; 3. anterior
spinal; 4. posterior cerebellar.
BRANCHES OF THE SECOND OR VERTEBRAL PORTION
1. The lateral spinal branches run through the intervertebral foramina into the
vertebral canal, and there divide into two branches: (a) The spinal, which ramifies
on the backs of the bodies of the cervical vertebræ; and (b) the medullary, which
runs along the spinal nerves, supplies the cord and its membranes, and anastomoses
with the arteries above and below. 2. The muscular branches supply the deep
muscles of the neck, and anastomose with the ascending cervical, occipital, and
deep cervical arteries.
BRANCHES OF THE THIRD OR OCCIPITAL PORTION
1. Muscular, to the muscles forming the suboccipital triangle; 2. anasto-
motic, to the branches of the occipital artery.
BRANCHES OF THE FOURTH OR CRANIAL PORTION
1. The posterior meningeal is a small branch given off as the vertebral artery
pierces the dura mater to enter the cranium. It supplies the bone and dura
mater of the posterior fossa of the skull, and anastomoses with the posterior
meningeal branches derived from the occipital and ascending pharyngeal arteries.
It gives branches to the falx cerebelli (fig. 387).
2. The posterior spinal artery runs downwards obliquely along the side of the
medulla to the back of the cord, down which it passes behind the roots of the spinal
nerves, being reinforced by lateral branches running inwards along these nerves, in
the neck from the vertebral, in the dorsal region from the intercostals, and in the
lumbar region from the lumbar arteries. It can be traced as low as the end of the
spinal cord.
3. The anterior spinal artery comes off from the vertebral a little below its
termination in the basilar artery. Descending obliquely inwards in front of the
medulla, it unites on a level with the foramen magnum with its fellow of the
opposite side. The single vessel thus formed runs downwards in front of the spinal
cord beneath the pia mater as far as the termination of the cord, being reinforced
by the lateral spinal branches the whole way down (fig. 387). The spinal arteries
are described in detail with the anatomy of the spinal cord.
4. The posterior inferior cerebellar (fig. 340)-the largest branch of the vertebral
-arises from that vessel just before it joins its fellow to form the basilar artery. At
times it may come off from the basilar itself. It runs, at first outwards across the
restiform body between the origin of the pneumogastric and hypoglossal nerves, and,.
descending towards the vallecula, there divides into two branches, an internal and
external. (a) The internal or inferior vermiform branch runs backwards between
the vermiform process and the lateral hemisphere of the cerebellum. It supplies
the vermiform process, and anastomoses with the artery of the opposite side, and
with the superior vermiform branch of the superior cerebellar. (b) The external or
hemispheral branch runs outwards, and, ramifying over the under surface of the

BASILAR
543
cerebellar hemisphere, supplies its cortex, and anastomoses along its outer margin
with the superior cerebellar arteries.
From the undivided trunk of the posterior inferior cerebellar artery branches
are given to the choroidal plexus and the fourth ventricle.
THE BASILAR ARTERY
The basilar artery is formed by the confluence of the right and left vertebral
arteries, which meet at an acute angle at the lower border of the pons Varolii. It
runs forwards and upwards in a slight groove in the middle line of the pons, and
divides at the upper border of that structure at the level of the pretentorial opening
into the two posterior cerebral arteries.
BRANCHES OF THE BASILAR ARTERY
The branches of the basilar artery are:-1. Transverse or pontal; 2. internal
auditory; 3. anterior cerebellar; 4. superior cerebellar; 5. posterior cerebral.
1. The transverse or pontal arteries are numerous small vessels which come
off at right angles on either side of the basilar artery, and, passing outwards over
the pons, supply that structure and adjacent parts of the brain.
2. The internal auditory artery, a long slender vessel, accompanies the auditory
nerve into the internal auditory meatus (fig. 387). It here lies between the facial and
auditory nerves, and at the bottom of the meatus passes into the internal ear,
and anastomoses with the other auditory arteries. (See INTERNAL EAR.)
3. The anterior cerebellar-or anterior inferior cerebellar artery, as it is some-
times called-arises from the basilar soon after its origin, passes outwards and
backwards across the pons, and then over the crus cerebelli to the front part of
the under surface of the cerebellum. It anastomoses with the posterior inferior
cerebellar artery (fig. 340).
4. The superior cerebellar comes off from the basilar immediately behind its
bifurcation into the posterior cerebral arteries. It courses outwards and backwards
over the pons, in a curve roughly corresponding to that of the posterior cerebral
artery, from which it is separated by the third cranial nerve; but, soon sinking
into the groove between the pons and the crus cerebri, it curves round the latter
structure on to the upper surface of the cerebellum, lying nearly parallel to the
fourth nerve. Here it divides into two branches, an internal and external.
(a) The
internal or superior vermiform branch courses backwards along the superior
vermiform process, anastomosing with its fellow of the opposite side, and at the
posterior notch of the cerebellum with the inferior vermiform branch of the posterior
inferior cerebellar artery. (b) The external or hemispheral branch runs outwards
to the circumference of the cerebellum, anastomosing with the external branch of
the inferior posterior cerebellar artery.
Branches are given off from the main trunk of the superior cerebellar artery,
or from its internal branch to the valve of Vieussens, the optic lobes, the pineal
gland, and the choroid plexus.
5. The posterior cerebral arteries are the two terminal branches into which the
basilar bifurcates at the upper border of the pons immediately behind the posterior
perforated space. Each artery runs at first outwards and a little forwards across
the crus cerebri immediately in front of the third nerve, which separates it from
the superior cerebellar artery. After receiving the posterior communicating artery,
which runs backwards from the internal carotid, the posterior cerebral turns back-
wards on to the under surface of the cerebral hemisphere, where it breaks up into
branches for the supply of the temporo-sphenoidal and occipital lobes.



544
THE ARTERIES
The branches of the posterior cerebral artery may be divided into the ganglionic
or central, and the cortical or hemispheral.
(a) The ganglionic or central branches, are divided into the postero-median; the
posterior choroid; and the postero-lateral. (i) The postero-median branches come
off from the posterior cerebral near its origin, and, passing through the cerebral
substance forming the posterior perforated spot, supply the inner part of the optic
thalamus and the walls of the third ventricle; (ii) the posterior choroid branch passes
through the transverse fissure to the velum interpositum and choroid plexus; (iii)
the postero-lateral branches arise external to the spot where the posterior cerebral
artery is joined by the posterior communicating. They run to the posterior part of
the optic thalamus and give branches to the crus cerebri and optic lobes or corpora
quadrigemina.
(b) The cortical or hemispheral branches are distributed as follows:-(i) the
uncinate, a branch to the anterior part of the uncinate convolution; (ii) the temporal,
a branch to the inferior part of the temporal lobe; and (iii) the temporo-occipital,
a branch to the cuneus, lingual convolution, and outer surface of the occipital lobe.
Here it may be stated, not only in reference to the branches of the posterior
cerebral artery, but also with respect to the branches of the anterior and middle
cerebral arteries, which are described with the internal carotid (page 534), that there
is no anastomosis between the cortical and central branches. The cortical and
the central form two distinct and separate systems. The cortical may or may
not anastomose with each other, but the communication between the neigh-
bouring cortical branches is seldom sufficient to maintain the nutrition of an area
when the vessel that normally supplies it is obstructed. The central branches are
so-called end-vessels and do not anastomose with each other. Hence obstruction
of the middle cerebral or Sylvian artery leads to softening of the area supplied by
its central branches, but not always to softening of the region supplied by its cortical
branches. Indeed the cortical region may escape completely, although the central
area is irreparably disorganised. The gross anastomosis of the posterior cerebral with
the anterior and middle cerebral arteries through the circle of Willis is described
with the branches of the internal carotid (page 535).
SUMMARY OF THE DISTRIBUTION OF THE CEREBRAL ARTERIES
Here it may be of advantage to give a brief summary of the distribution of the
anterior, middle, and posterior cerebral arteries, the branches of which have already
been described in detail. The branches of each are divided into the central or
ganglionic, and the cortical or hemispheral. The central branches arise at the
commencement of the cerebral arteries about the circle of Willis, whilst the
cortical are derived chiefly from the termination of these vessels.
(A) The central branches are divided into six sets-two median and four
lateral. 1. The two median are (1) The antero-median, which arise from the
anterior cerebral and the anterior communicating, and supply the fore end of the
caudate nucleus, and (2) the postero-median, which arise from the posterior cerebral,
and supply the inner part of the optic thalamus and neighbouring wall of the third
ventricle. 2. The four lateral, two on each side, are also divided into antero-lateral,
and postero-lateral. (1) The antero-lateral arise from the middle cerebral, and,
passing through the anterior perforated spot, supply the lenticular nucleus, the
posterior part of the caudate nucleus, the internal and external capsules, and the
outer part of the optic thalamus. (2) The postero-lateral arise from the posterior
cerebral, and supply the hinder part of the optic thalamus, the crus, and the optic
lobes or corpora quadrigemina.
(B) The cortical branches ramify in the pia mater, giving off branches to the

INFERIOR THYROID
545
cortical substance, some of which extend through it to the underlying white sub-
stance. The cortical branches of the anterior cerebral, roughly speaking, supply
the median surface of the frontal lobe as far as the precuneus, the inner part of its
orbital surface, and part of its convex surface, viz. the highest part of the ascending
frontal and the first and most of the second frontal convolutions. The cortical
branches of the middle cerebral-or Sylvian artery as it is often called, because
of its relation to the Sylvian fissure-supply the most important area, namely, the
motor convolutions; and also the largest, namely, the inferior frontal, the ascending
parietal, part of the inferior parietal, the supramarginal and angular, the posterior
part of the superior parietal, the first temporal, and the anterior part of the second
and third temporal convolutions. The cortical branches of the posterior cerebral
supply the occipital lobe, and the inferior aspect of the temporal lobe.
It will be seen, therefore, that the middle cerebral supplies the motor region, both
central and cortical, except a part of the leg centre. It also supplies the region of
the cortex that subserves cutaneous sensibility, the cortical auditory centre, and in
part the higher visual centre. It likewise supplies all the cortical regions concerned
in speech processes in the left hemisphere. The anterior cerebral supplies only a
small part of the motor region-namely, the part of the leg centre that occupies
the paracentral lobule and the highest part of the ascending frontal convolution.
The posterior cerebral supplies the visual path from the middle of the tract
backwards, and the half vision centre in the occipital lobe. It supplies also the
corpora quadrigemina and the sensory part of the internal capsule.

THE THYROID AXIS
The thyroid axis arises from the upper and front part of the subclavian artery,
usually opposite the internal mammary, and a little internal to the inner border of
the scalenus anticus. It is a short thick trunk, and divides almost immediately
into three radiating branches-namely, the inferior thyroid, the suprascapular,
and the transverse cervical (fig. 330).
Occasionally the posterior scapular branch of the transverse cervical arises from
the third portion of the subclavian; the superficial cervical, the other branch into
which the transverse cervical divides, then commonly comes off from the axis.

THE INFERIOR THYROID ARTERY
The inferior thyroid, the largest of the three branches into which the thyroid
axis divides, ascends tortuously upwards and inwards in front of the vertebral artery,
the recurrent laryngeal nerve, and the longus colli muscle, and behind the common
carotid, and the sympathetic nerve or its middle cervical ganglion, to the thyroid
body, where it anastomoses with the superior thyroid artery and the artery of the
opposite side. It gives off the following branches :-(1) Muscular; (2) ascending
cervical; (3) œsophageal; (4) tracheal; and (5) inferior laryngeal.
(1) The muscular branches supply the scalenus anticus, longus colli, sterno-
hyoid, sterno-thyroid, and omo-hyoid muscles, and the inferior constrictor muscle of
the pharynx.
(2) The ascending cervical (fig. 329) is given off from the inferior thyroid as
that vessel is passing beneath the carotid sheath. It ascends between the scalenus
anticus and the rectus capitis anticus major, lying parallel and a little internal to
the phrenic nerve and behind the internal jugular vein. It anastomoses with the
vertebral, ascending pharyngeal, and occipital arteries, and supplies the following
branches: (a) Muscular, to the deep muscles of the neck; (b) spinal, which enter
NN
546
THE ARTERIES
the spinal canal with spinal branches of the vertebral artery; and (c) phrenic, to
the phrenic nerve. Two veins accompany the ascending cervical artery, and end
in the innominate vein.
(3) The œsophageal branches of the inferior thyroid artery supply the so-
phagus, and anastomose with the other arteries supplying that tube.
(4) The tracheal branches ramify on the trachea, where they anastomose with
the tracheal branches of the superior thyroid and bronchial arteries.
(5) The inferior laryngeal branch passes along the trachea to the back of the
cricoid cartilage in company with the recurrent laryngeal nerve. It enters the
larynx beneath the inferior constrictor. Its further distribution in that organ is
described under LARYNX.
THE SUPRASCAPULAR ARTERY
The suprascapular, or transversalis humeri, passes more or less transversely
outwards across the root of the neck, lying first beneath the sterno-mastoid, and
then in the subclavian triangle behind the clavicle and subclavius muscle. At
the external angle of this space it is joined by the suprascapular nerve, sinks
beneath the posterior belly of the omo-hyoid, and passes over the ligament bridging
the scapular notch, the nerve passing through the notch (fig. 343). It then ramifies
in the supraspinous fossa of the scapula, and, winding downwards round the base
of the spine over the neck of the scapula, enters the infraspinous fossa, and ter-
minates by anastomosing with the dorsal scapular and posterior scapular arteries.
As it lies under cover of the sterno-mastoid muscle, it crosses the phrenic nerve and
the scalenus anticus; and as it courses through the subclavian triangle, it is sepa-
rated by the cervical fascia which descends from the omo-hyoid to the first rib, from
the subclavian artery and brachial plexus of nerves. If this artery is seen in tying
the subclavian it should not be injured, as it is one of the chief vessels by which
the collateral circulation is carried on after ligature of the subclavian in the third
part of its course. At the outer part of the subclavian triangle it is covered by the
trapezius, and after passing over the scapular ligament it pierces the supraspinous
fascia and passes beneath the supra-spinatus muscle, and ramifies between it and
the bone. In the infraspinous fossa it lies between the infra-spinatus and the bone.
The artery is accompanied by two veins.
The branches of the suprascapular are as follow:-(1) The inferior sterno-
mastoid, given off to that muscle as the vessel crosses behind it; (2) the subclavian,
to the subclavius muscle; (3) the nutrient, to the clavicle; (4) the suprasternal,
which passes over the sternal end of the clavicle to the skin of the upper part of
the chest; (5) the acromial, to the arterial rete or plexus on the acromial pro-
cess, to reach which it pierces the trapezius; (6) the articular, to the acromio-
clavicular joint and shoulder joint; (7) the subscapular, given off as the artery
is passing over the suprascapular ligament, descends to the subscapular fossa
between the subscapularis and the bone, and anastomoses with the infrascapular
branch of the dorsal scapular artery, and with the subscapular and posterior
scapular arteries; (8) the supraspinous branches, which ramify in the supra-
spinous fossa, and supply the supra-spinatus muscle and the periosteum and the
nutrient artery to the bone; (9) the infraspinous branches, which ramify in a
similar way in the infraspinous fossa, giving off like twigs to the infra-spinatus
muscle, the periosteum, and the bone.
THE TRANSVERSE CERVICAL ARTERY
The transverse cervical or transversalis colli artery-somewhat larger than
the suprascapular artery-runs like the latter vessel transversely outwards across

TRANSVERSE CERVICAL
547
the root of the neck, but on a slightly higher plane, and a little above the clavicle.
At its origin from the thyroid axis it lies under the sterno-mastoid; on leaving the
cover of this muscle, it crosses the upper part of the subclavian triangle, lying here
only beneath the platysma and cervical fascia; further outwards, it passes beneath
the anterior margin of the trapezius and omo-hyoid muscle, and at the outer
margin of the levator anguli scapula divides into the posterior scapular and super-
ficial cervical arteries. In this course it crosses the phrenic nerve, the scalenus
anticus, the brachial plexus, and the scalenus medius. At times it passes between
the cords of the brachial plexus.
The terminal branches of the transverse cervical artery are:-(1) The posterior
scapular; and (2) the superficial cervical. The posterior scapular occasionally arises
from the third portion of the subclavian artery.
FIG. 343.-DIAGRAM OF ANASTOMOSES OF THE SCAPULAR ARTERIES.
Posterior scapular.
artery
Supraspinous branch
Subscapular branch
Branch of intercostal.
artery
Continuation of
posterior scapular
artery
Subscapular branch
Supraspinous branch
-Suprascapular artery
Acromial
branch of
acromio-
thoracic
Acromial rete
Subscapular branch
of suprascapular
artery
Infraspinous branch
Subscapular branch
of axillary artery
-Dorsal scapular branch
of subscapular
-Infrascapular branch of
dorsal scapular
-Continuation of sub-
scapular artery
(1) The posterior scapular-the apparent continuation of the transverse cervical
artery begins at the outer border of the levator anguli scapula, and, continuing
its course beneath this muscle to the upper and posterior angle of the scapula,
turns downwards and skirts along the posterior border of the scapula, between the
serratus magnus in front and the levator anguli scapulæ and rhomboideus minor
and major behind, to the inferior angle, where it anastomoses with the subscapular
artery. It gives off the following branches :-(a) Supraspinous, which ramifies
between the supraspinous muscle and the trapezius, and sends branches through
the muscle into the fossa, to anastomose with the suprascapular artery. (b) Infra-
spinous branches, one or more of which enter the infraspinous fossa, and ana-
stomose with the dorsal scapular. (c) Subscapular branches, which enter the
NN 2
548
THE ARTERIES
subscapular fossa, and anastomose with the suprascapular, infrascapular, and
subscapular arteries. (d) Muscular branches, to the muscles between which it
runs and to the latissimus dorsi. These branches anastomose with the posterior
divisions of the intercostal arteries.
(2) The superficial cervical artery, smaller than the posterior scapular, ascends
under cover of the anterior margin of the trapezius, lying upon the levator anguli
scapulæ and splenius muscles. It supplies branches to the trapezius, levator anguli
scapulæ, and splenius muscles, and the posterior chain of lymphatic glands. It
anastomoses with the superficial branch of the princeps cervicis which descends from
the occipital between the splenius and complexus. It is accompanied by two veins.
This artery may arise directly from the thyroid axis, or from the third part of the
subclavian artery.
THE INTERNAL MAMMARY ARTERY
The internal mammary artery (fig. 344) comes off from the lower part of the
first portion of the subclavian, usually opposite the thyroid axis, close to the inner
edge of the scalenus anticus, occasionally opposite the vertebral, or at a spot
between these two vessels. It descends with a slight inclination forwards and
inwards, under cover of the clavicle, and enters the thorax behind the cartilage of
the first rib, and thence passes down behind the cartilages of the next succeeding
ribs, about half an inch from the external margin of the sternum, to the sixth
interspace, where it divides into the superior epigastric and musculo-phrenic. It
is accompanied by two veins, which unite into one trunk behind the first intercostal
muscle, and pass to the inner side of the artery into the corresponding vena
innominata; occasionally on the right side into the vena cava superior direct.
The artery may be divided into two portions, the cervical and the thoracic.
The cervical portion is covered by the sterno-mastoid muscle, subclavian vein,
and internal jugular vein, and is crossed obliquely, from without inwards, by the
phrenic nerve. It rests upon the pleura and courses round the upper part of the
innominate vein. There is no branch from this part of the artery.
The thoracic portion lies behind the cartilages of the six upper ribs, and
in the interspace between the ribs has in front of it the pectoralis major and the
internal intercostal muscles and the external intercostal membrane. Behind, it is
in contact above with the pleura, but it is separated from it lower down by slips
of the triangularis sterni. On the left side the artery between the fourth and
sixth rib may be said to be in the anterior mediastinum the pleura here forming
a notch for the heart. In the first, second, and third spaces the artery, if wounded,
can be easily tied; but in the fourth space the operation is attended with more
difficulty. The remaining spaces are so narrow that a portion of the cartilage
would have to be removed to expose the vessel.
The branches of the internal mammary artery are:-(1) The superior phrenic;
(2) the mediastinal, or thymic; (3) the pericardiac; (4) the sternal; (5) the anterior
intercostals; (6) the perforating; (7) the lateral infracostal; (8) the superior
epigastric; and (9) the musculo-phrenic.
(1) The superior phrenic, or comes nervi phrenici, is a long slender vessel which
comes off from the internal mammary just after it has entered the chest, and
descends with the phrenic nerve, at first between the pleura and innominate vein;
then between the pleura and the vena cava superior; and lastly, between the
pleura and the pericardium to the diaphragm, where it anastomoses with the other
diaphragmatic arteries. It gives branches both to the pleura and pericardium.
(2) The mediastinal or thymic branches come off irregularly from the internal
mammary. They are of small size, and supply the connective tissue, fat, and



INTERNAL MAMMARY
549
lymphatics in the superior and anterior mediastina and the remains of the thymus
gland.
(3) The pericardiac branches are distributed to the anterior surface of the
pericardium.
(4) The sternal branches enter the nutrient foramina in the sternum, and also
supply the triangularis sterni.
(5) The anterior intercostal arteries (fig. 344)-two in each of the five or six
upper intercostal spaces-run outwards from the internal mammary artery, along
the lower border of the rib above and the upper border of the rib below, and
FIG. 344.-SCHEME OF THE INTERNAL MAMMARY ARTERY.
PHRENIC NERVE-
Subclavian vein-
Common carotid artery
Internal jugular vein
Subclavian vein
Scalenus anticus muscle
Anterior intercostal branch.
STERNUM
Internal intercostal muscle
Anterior intercostal branch
Perforating branch
Superior epigastric artery
Musculo-phrenic artery
Deep circumflex iliac artery-
Deep epigastric artery
anastomose with the corresponding upper and lower branches of the aortic inter-
costals. Each pair of branches sometimes arises by a common trunk from the
internal mammary, which in this case soon divides into an upper and lower branch,
as above described. They lie at first between the internal intercostal muscles and
the pleura; afterwards between the external and internal intercostal muscles. They
supply the contiguous muscles, the pectoralis major, and the ribs.
(6) The perforating or anterior perforating branches-five or six in number,
one corresponding to each of the five or six upper spaces-come off from the front
of the internal mammary, between the superior and inferior anterior intercostals,
and, perforating the internal intercostal muscles, pass forwards between the costal
550
THE ARTERIES
cartilages to the pectoralis major, which they supply. The terminal twigs perforate
that muscle close to the sternum, and are distributed to the integument. The
second, third, and fourth perforating supply the inner and deep surface of the
mammary gland, and become greatly enlarged during lactation. They frequently
require ligation in excision of the breast.
(7) The lateral infracostal artery (Macalister) is given off close to the first rib,
and descends behind the ribs just external to the costal cartilages. It anastomoses
with the upper intercostal arteries. This vessel is often of insignificant size, or
absent.
(8) The superior epigastric artery (fig. 344), or internal terminal branch of
the internal mammary artery, leaves the thorax behind the seventh costal carti-
lage by passing through the costo-xiphoid space in the diaphragm. It is the direct
prolongation of the internal mammary downwards. In the abdomen it descends
behind the rectus muscle, between its posterior surface and its sheath, and, lower,
entering the substance of the muscle, anastomoses with the deep epigastric, a
branch of the external iliac. It gives off the following small branches :--(a) The
phrenic, to the diaphragm; (b) the xiphoid, which crosses in front of the ensi-
form cartilage, and anastomoses with the artery of the opposite side; (c) the cuta-
neous, which perforate the anterior layer of the sheath of the rectus and supply the
integuments; (d) the muscular, to the rectus muscle, some of which perforate the
rectus sheath laterally, and are distributed to the oblique muscles; (e) the hepatic
(on the right side only), which pass along the falciform ligament to the liver, and
anastomose with the hepatic artery; (f) the peritoneal which perforate the posterior
layer of the sheath of the rectus, and ramify on the peritoneum.
(9) The musculo-phrenic, or external terminal branch of the internal mammary.
artery, skirts outwards and downwards behind the costal cartilages of the false ribs
along the costal attachments of the diaphragm, which it perforates opposite the
ninth rib. It terminates, much reduced in size, at the tenth or eleventh intercostal
space by anastomosing with the ascending branch of the deep circumflex iliac artery.
It gives off in its course the following small branches :-(a) The phrenic for the
supply of the diaphragm; (b) the anterior intercostals, two in number for each of
the lower five or six intercostal spaces, are distributed like those to the upper spaces,
already described, and anastomose like them with the corresponding branches of the
lower aortic intercostals; (c) the muscular for the supply of the oblique muscles
of the abdomen.
BRANCHES OF THE SECOND PART OF THE SUBCLAVIAN ARTERY
THE SUPERIOR INTERCOSTAL ARTERY
1. The superior intercostal artery (fig. 345) usually arises from the back part of
the second portion of the subclavian artery, behind the scalenus anticus on the
right side, but sometimes just internal to that muscle on the left side. It at first
runs backwards and a little upwards above the apex of the pleura, and then turns
downwards and enters the thorax in front of the neck of the first rib. It terminates
in a branch which runs forwards in the first intercostal space. Frequently, and
especially on the right side, it is continued in front of the neck of the second rib, and
supplies a branch to the second intercostal space. This branch may then be
reinforced by an intercostal from the aorta, which supplies the space when the
branch is not present. As the superior intercostal crosses the neck of the first
rib, it lies internal to the anterior branch of the first dorsal nerve, and externa
to the superior thoracic ganglion of the sympathetic. That part of the superior
intercostal which intervenes between its origin from the subclavian and its first
branch, is sometimes called the costo-cervical artery.

SUPERIOR INTERCOSTAL
551
Branches. The superior intercostal gives off:-(1) The deep cervical; (2) the
first intercostal; and (3) the arteria aberrans.
X (1) The deep cervical branch is given off from the superior intercostal just
before the latter enters the thorax. It passes directly backwards, first between the
seventh and eighth cervical nerves, and then between the transverse process of the
seventh cervical vertebra and the neck of the first rib, having the body of the
seventh cervical vertebra to its inner side, and the intertransverse muscle to its outer
side. It then turns upwards in the groove between the transverse and spinous
processes of the cervical vertebræ lying upon the semispinalis colli. It is covered
by the complexus. Between these muscles, near the axis, it anastomoses with the
deep branch of the princeps cervicis of the occipital artery. The deep cervical is
homologous in its course to the posterior branch of an aortic intercostal, being
morphologically the posterior branch of the intercostal artery for the seventh
FIG. 345.-SCHEME OF THE SUPERIOR INTERCOSTAL ARTERY.
Scalenus ant cus muscle
Deep cervical branch
FIRST DORSAL NERVE
FIRST INTERCOSTAL
NERVE
Subclavian artery
SECOND INTERCOSTAL
NERVE
Anterior
intercostal artery
THIRD
INTERCOSTAL
NERVE
2ND RIB
VISTRIB
2ND
RIB
3RD RIB
Anterior
intercostal artery-
Internal
mammary artery
DRIB
Intercostal vessels.
of third space
7TH CERVICAL
IST DORSAL
SYMPATHETIC
NERVE
INFERIOR CER-
VICAL GANGLION
}
Superior
intercertal artery
2ND DORSAL
Arteria aberrans
-Branch from
first aortic
intercostal
4-TH RIB
3RD DORSAL
4TH DORSAL
AORTA
Arteria aberrans
First aortic
intercostal
artery
-Second aortic
intercostal
artery
Intercostal vessels of fourth space
cervical space. It gives off the following small branches :-(a) Muscular, to the
semispinalis colli and complexus; (b) anastomotic, which anastomose with branches
of the vertebral, ascending cervical and princeps cervicis arteries; and (c) vertebral
or spinal, which enters the spinal canal through the intervertebral foramen with
the eighth cervical nerve.
(2) The first intercostal branch runs forwards in the first intercostal space, and,
like the second intercostal branch, which, when present, runs to the second space on
the right side, resembles in its course and distribution the succeeding intercostals
derived from the aorta. (See BRANCHES OF THORACIC AORTA.)
(3) The arteria aberrans, when present, comes off from the inner side of the
right superior intercostal, and occasionally from the right subclavian itself. It
descends as a delicate vessel into the thorax, passing backwards and inwards
behind the œsophagus as far as the third thoracic vertebra, where in some cases it is
552
THE ARTERIES
found to anastomose with a similar delicate branch coming off from the aorta below
the ductus arteriosus. This anastomosis, which represents the remains of the right
dorsal aortic stem, may become enlarged, and the subclavian artery on the right side
be derived from the arch of the aorta. This accounts for the subclavian in such
circumstances passing behind the oesophagus. (See VARIATIONS OF THE ARCH OF
THE AORTA.)
THE AXILLARY ARTERY
The term axillary is applied to that portion of the main arterial stem of the upper
limb that passes through the axilla. The axillary artery therefore is continuous
with the subclavian above and with the brachial below. It extends from the outer
border of the first rib to the lower edge of the teres major muscle, and has the
shoulder joint and the neck of the humerus to its outer side. When the arm is
placed close to the side of the body, the artery forms a gentle curve with its
convexity upwards; but when the arm is carried out from the side at right angles
to the trunk in the ordinary dissecting position, the vessel takes a nearly straight
course, which will then be indicated by a line drawn from the middle of the
clavicle to a spot midway between the condyles of the humerus. The axillary
artery is at first deeply placed beneath the pectoral muscles, but in its lower third
is superficial, being covered only by the skin and the superficial fascia and deep
fascia. It is divided into three parts-first, second, and third, according as it lies
above, beneath, or below the pectoralis minor.
THE FIRST PART OF THE AXILLARY ARTERY
The first part of the axillary artery extends from the outer border of the first
rib to the upper border of the pectoralis minor. It measures about an inch in
length (2.5 cm.).
Relations. In front it is covered by the skin, superficial fascia, the origin of
the platysma, the deep fascia, the pectoralis major, the costo-coracoid membrane,
the subclavius muscle and the clavicle when the arm hangs down by the side. The
cephalic and acromio-thoracic veins, the external anterior thoracic nerve, and the
axillary lymphatic trunk, cross over it. A layer of the deep cervical fascia which
has passed under the clavicle also descends in front of it.
Behind, it rests upon the first intercostal space and first intercostal muscle, the
second digitation and sometimes a portion of the third digitation of the serratus
magnus muscle, and a part of the second rib. The posterior or external respiratory
nerve of Bell, on its way to the serratus magnus muscle, passes behind it.
To its outer side, and somewhat on a higher plane, are the cords of the brachial
plexus.
To its inner side, and on a slightly anterior plane, is the axillary vein. The
anterior internal thoracic nerve courses between the vein and the artery.

THE SECOND PART OF THE AXILLARY ARTERY
The second part of the axillary artery (fig. 346) lies beneath the pectoralis
minor deep in the axilla. It measures a little more than an inch in length (3 cm.).
Relations. In front, in addition to the pectoralis minor, it is covered by the
pectoralis major and the integuments.

AXILLARY
553
Behind, it is separated by a considerable interval containing loose connective
tissue and fat from the subscapularis muscle; whilst behind, and in contact with
it, is the posterior cord of the brachial plexus.
To the inner side, but separated from the artery by the inner cord of the
brachial plexus, is the axillary vein.
To the outer side is the outer cord of the brachial plexus, and at some little
distance the coracoid process.
It is thus seen that the second portion of the axillary artery is surrounded on
three sides by the cords of the brachial plexus-one behind, one internal, and one
external.
THE THIRD PART OF THE AXILLARY ARTERY
The third part of the axillary artery (fig. 346) extends from the lower border
of the pectoralis minor to the lower border of the teres major. Its upper half
lies deeply placed within the axilla, beneath the lower edge of the pectoralis major
muscle, but its lower half is in the arm external to the axilla, and is uncovered by
muscle. It measures about three inches in length (7.5 cm.).
Relations. In front it has, in addition to the skin and superficial fascia, the
pectoralis major above, and lower down the deep fascia of the arm. It is crossed
obliquely by the inner root of the median nerve and by the outer brachial vena

comes.
Behind, it lies successively upon the subscapularis, the latissimus dorsi, and teres
major muscles. From the first-named muscle it is separated at first by a consider-
able mass of fat and cellular tissue. The musculo-spiral and circumflex nerves
intervene between the artery and the muscles.
On its outer side it is separated from the bone by the coraco-brachialis, by which
it is partly overlapped, this muscle and the short head of the biceps serving as a
guide to the artery in ligature. For a part of its course it has also the musculo-
cutaneous nerve and the outer root of the median nerve to its outer side.
To its inner side it has the axillary vein, the ulnar nerve, the internal cutaneous
nerve, the lesser internal cutaneous nerve, and the inner root of the median nerve.
The ulnar nerve is between the artery and the vein. The internal cutaneous nerve
is a little in front of the artery as well as internal to it.


Variations in the Axillary Artery
The chief variations in the axillary artery are:-(a) It may give off the radial artery;
(b) more rarely, the ulnar artery; (c) still more rarely, the interosseous artery, or a vas
aberrans; (d) it may give off a common trunk, from which may arise the subscapular,
the anterior and posterior circumflex, and the superior and inferior profunda arteries. The
branches of the brachial plexus usually surround this common trunk, and not what is
apparently the main brachial artery. The latter vessel indeed would seem in many of these
instances to be really an enlarged vas aberrans, and the common trunk the main brachial
artery, the lower portion of which has been obliterated, i.e. obliterated from the last branch
given off from the common trunk to the spot where it is again joined by the vas aberrans.
(e) The axillary artery may be covered in the third part of its course by a muscular slip (the
dorsi axillaris), derived from the upper part of the tendon of the latissimus dorsi, and always
present in early foetal life, though as a rule atrophied later.
BRANCHES OF THE AXILLARY ARTERY
The first part gives oft:-(1) The superior thoracic; and (2) the acromio-
thoracic.
The second part gives off :-(1) The long thoracic; and (2) the alar thoracic.
The third part gives off:-(1) The subscapular; (2) the anterior circumflex;
and (3) the posterior circumflex.

554
THE ARTERIES
FIG. 346. THE LOWER PART OF THE AXILLARY, THE BRACHIAL, AND THE RADIAL
AND ULNAR ARTERIES.
(From a dissection in the Hunterian Museum.)
CLAVICLE-
BRACHIAL PLEXUS
ACROMION
HEAD OF HUMERUS
Pectoralis minor, turned back
MUSCULO-CUTANEOUS
NERVE
BRANCH OF MUSCULO-CUTA-
NEOUS TO MEDIAN NERVE
Coraco-brachialis
Subscapularis
Acromio-thoracic artery
Axillary artery
MEDIAN NERVE
Subscapular artery
Brachial artery
Superior profunda artery
Biceps
Teres major
Latissimus dorsi
Long head of triceps
MUSCULO-SPIRAL NERVE
MUSCULAR BRANCH OF
MUSCULO-SPIRAL NERVE
MUSCULO-CUTANEOUS.
NERVE
BRANCH OF MUSCULO-
CUTANEOUS NERVE TO
BRACHIALIS ANTICUS
Brachialis anticus
MEDIAN NERVE
Inner brachial vena comes
MUSCULO-SPIRAL NERVE
Inferior profunda artery
Inner head of triceps
ULNAR NERVE
Anastomotica magna artery
Internal intermuscular septum
Radial recurrent artery
Supinator longus
Superficial median vein, cut short
MUSCULAR BRANCHES OF
MEDIAN NERVE
Pronator teres and superficial
flexor muscles, turned back
Anterior ulnar recurrent artery
Deep head of pronator radii
teres
Pronator radii teres
RADIAL NERVE
Radial artery
Cut edge of flexor sublimis
digitorum
MEDIAN NERVE
-Posterior ulnar recurrent artery
Superficial flexor muscles,
turned back
Anterior interosseous artery and
nerve
Fexor profundus digitorum
ULNAR NERVE
Flexor longus pollicis
Ulnar artery
Interosseous membrane with
cut edge of pronator
quadratus
AXILLARY
555
BRANCHES OF THE FIRST PART OF THE AXILLARY ARTERY
1. The superior or short thoracic is variously given off from the axillary artery,
usually either as a common trunk with the next branch, the acromial thoracic, or
a little above. It passes behind the axillary vein across the first intercostal space,
supplying the intercostal muscles and the upper portion of the serratus magnus, and
anastomoses with the intercostal arteries. At times it sends a branch between the
pectoralis major and minor, which then, as a rule, more or less takes the place of
the pectoral branch of the acromial thoracic.
2. The acromio-thoracic, or thoracic axis, arises from the front part of the
axillary just above the upper border of the pectoralis minor. It is a short trunk,
and coming off from the front of the artery pierces the costo-coracoid membrane,
and then divides into three or four small branches, named from their direction :-
(a) the acromial, or thoracica acromialis; (b) the humeral, or thoracica humeralis;
(c) the pectoral, or short thoracic of some authors; and (d) the clavicular.
(a) The acromial branch or branches pass outwards across the coracoid process,
frequently through the deltoid muscle, which they in part supply, to the acromion,
where they form, by anastomosing with the anterior and posterior circumflex and
suprascapular arteries, the so-called acromial rete, or plexus of vessels on the
surface of that process.
(b) The humeral branch-the descending branch of some authors-runs down-
wards with the cephalic vein in the interval between the pectoralis major and the
deltoid, and, supplying lateral offsets to these muscles and the adjacent integuments,
anastomoses with the anterior and posterior circumflex arteries.
(c) The pectoral branch passes between the pectoralis major and minor muscles,
both of which it supplies, and the superimposed mammary gland. In the female,
one or more of these branches which perforate the pectoralis major are often of
large size.
(d) The clavicular branch passes upwards beneath the clavicle, and supplies
the subclavius muscle, and anastomoses with the suprascapular artery.

BRANCHES OF THE SECOND PART OF THE AXILLARY ARTERY
1. The long thoracic artery-also called the external mammary-descends
along the lower border of the pectoralis minor, under cover of the pectoralis
major, to the walls of the chest. It supplies both pectoral muscles and the
serratus magnus, sends branches round the lower border of the pectoralis major to
the mammary gland, and terminates in the intercostal muscles by anastomosing
with the aortic intercostals and the internal mammary. It also furnishes branches
to the glands of the axilla. The branches to the mammary gland in the female
are often of large size.
2. The alar thoracic are small branches given off either directly from the axillary
artery to the lymphatic glands in the axilla, or from some of the other branches of
the first or second part of the axillary artery.


BRANCHES OF THE THIRD PART OF THE AXILLARY ARTERY
1. The subscapular artery is the largest branch of the axillary. It arises
opposite the lower border of the subscapularis, and runs downwards and inwards
along the anterior border of that muscle under cover of the latissimus dorsi as
far as the angle of the scapula, where it anastomoses with the dorsal scapular
posterior scapular, long thoracic, infrascapular, and the intercostal arteries. The
long subscapular nerve accompanies it. It supplies the subscapularis, teres major,

556
THE ARTERIES
latissimus dorsi, and serratus magnus muscles, and gives branches to the glands in
the axillary space. The course of this large vessel along the posterior border of
the axilla should be remembered in opening abscesses in the axilla, and in removing
enlarged glands from this space. It is accompanied by two veins, which usually
unite and then receive the dorsal scapular vein, and open as a single vein of large
size either into the axillary or at the confluence of the inner brachial vena comes
with the basilic vein.
About an inch to an inch and a half from its origin, the subscapular artery
gives off the following large branch:-
The dorsal scapular, arising from the subscapular, usually at the above-mentioned
FIG. 347.-THE DORSAL SCAPULAR ARTERY.
(From a dissection in the Museum of the Royal College of Surgeons.)
Supra-spinatus Suprascapular artery
Posterior scapular artery
Rhomboideus minor
Levator anguli scapulæ
Trapezius
Rhomboideus major
Teres major muscle
Infra-spinatus
Triceps
Deltoid, insertion
Deltoid
Deltoid muscle
Triceps
Teres major, insertion
Dorsalis scapulce artery Posterior circumflex artery
spot, passes backwards through the triangular space bounded by the subscapularis
above, the teres major below, and the long head of the triceps externally, and then
between the teres minor and the axillary border of the scapula, which it commonly
grooves. It thus reaches the infraspinous fossa, where, under cover of the infra-
spinatus, it anastomoses with the suprascapular and posterior scapular arteries
(fig. 347). As it passes through the triangular space, it gives off a ventral branch,
sometimes called the infrascapular, which ramifies between the subscapularis and
the bone, supplying branches to the subscapularis, to the scapula, and to the shoulder
joint. A second branch is often given off near the triangular space and passes down-
wards between the teres major and teres minor, supplying both muscles (fig. 348).

AXILLARY
557
The chief variations in the subscapular artery are:-(a) It may come off with the
posterior circumflex; (b) it may arise from a trunk common to several other of the
branches of the third part of the axillary artery and upper part of the brachial artery; and
(c) its dorsal scapular branch may arise from the axillary direct.
2. The anterior circumflex, usually quite a small vessel, comes off from the
outer side of the axillary artery, generally opposite the posterior circumflex. It
passes beneath the coraco-brachialis and short and long heads of the biceps, winding
transversely round the front of the surgical neck of the humerus, across the bicipital
groove, and anastomoses with the posterior circumflex and acromial thoracic arteries.
It gives off the following small branches: (a) the bicipital or ascending, which runs
up the bicipital groove to supply the long tendon of the biceps and the shoulder
joint; and (b) a pectoral or descending branch, which runs downwards along the
insertion of the pectoralis major, and supplies the tendon of that muscle. The
anterior circumflex artery, in consequence of its being close to the bone, is some-
times difficult to secure in the operation for excision of the shoulder joint.
Chief variations.-(a) It may be given off from the posterior circumflex; or (b) from a
stem common to it and several other vessels. (See VARIATIONS IN THE AXILLARY ARTERY,
page 553.)
FIG. 348.-THE POSTERIOR CIRCUMFLEX ARTERY.
(From a dissection by Mr. Horner in the Museum of St. Bartholomew's Hospital.)
Infra-spinatus
ACROMIAL PROCESS
Suprascapular artery
SPINE OF SCAPULA
Teres minor
Superior profunda artery
Posterior circumflex artery
Deltoid, reflected
Infra-spinatus
MUSCULO-SPIRAL NERVE
Outer head of triceps
EXTERNAL CUTANEOUS
BRANCH OF
MUSCULO-
SPIRAL NERVE
Teres major
Dorsal scapular artery
Branch of dorsal scapular artery
NERVE TO TERES MINOR
Coraco-brachialis
Long head of triceps
CUTANEOUS BRANCH OF CIRCUMFLEX NERVE
3. The posterior circumflex artery (fig. 348) arises from the hinder part of the
axillary, just below the lower border of the subscapularis muscle. It passes
through the quadrilateral space, bounded by the teres minor above, the latissimus
dorsi and teres major below, the humerus externally, and the long head of the
triceps internally, and, winding round the back of the humerus beneath the deltoid,
breaks up under cover of that muscle into a leash of branches, which for the most

558
THE ARTERIES
part enter its substance. The circumflex nerve and two venæ comites run with it.
It anastomoses with the anterior circumflex, the arteries on the acromion, and the
superior profunda artery.
In addition to the leash of vessels to the deltoid, it gives off the following small
branches :-(a) nutrient, to the greater tuberosity of the humerus; (b) articular,
to the back of the shoulder joint; (c) acromial, to the plexus on the acromion; and
(d) muscular, to the teres minor and long and short heads of the triceps. One or
more of these branches to the triceps (the tricipital) descend either between the
outer and long head, or in the substance of that muscle to anastomose with an
FIG. 349.-THE ANASTOMOSES ABOUT THE SCAPULA.
Posterior scapular
artery
Supraspinous branch.
Subscapular branch
Branch of intercostal
artery
Continuation of
posterior scapular
artery
Subscapular branch
Supraspinous branch
Suprascapular artery
Acromial
branch of
acromio-
thoracic
Acromial rete
Subscapular branch
of suprascapular
artery
Infraspinous branch
Subscapular branch
of axillary artery
Dorsal scapular branch
of subscapular
Infrascapular branch of
dorsal scapular
-Continuation of sub-
scapular artery
ascending branch from the superior profunda artery. It is by means of this
anastomosis that the collateral circulation is chiefly carried on when the axillary
or the brachial artery is tied between the origins of the posterior circumflex and
superior profunda arteries (fig. 330).
The chief variations in the posterior circumflex are:-(a) It may arise with the sub-
scapular artery as a common trunk. (b) It may come off from the brachial, and run up
behind the teres major to the quadrilateral space. (c) It may give off the inferior pro-
funda, the anterior circumflex, or the dorsal scapular. (d) It may be double. (e) It may
form one of the vessels arising from a trunk common to several branches of the axillary
and brachial arteries. (See VARIATIONS IN THE AXILLARY ARTERY, page 553.)

BRACHIAL
559
THE BRACHIAL ARTERY
The brachial artery, the continuation of the axillary, extends from the lower
border of the teres major to a little below the centre of the crease at the bend of
the elbow, where it divides, opposite the junction of the head with the neck of the
FIG. 350.-THE BRACHIAL ARTERY.
(From a dissection in the Museum of the Royal College of Surgeons.)
Suprascapular artery and nerve
CIRCUMFLEX
NERVE
SUBSCAPULAR
NERVE
Subscapular vessels
Triceps
Basilic vein
ULNAR NERVE
Triceps
Inferior profunda artery
Biceps
Axillary artery
and vein
MUSCULO-CUTA-
NEOUS and in-
ternally outer
head of MEDIAN
NERVE
One of the brachial
veins
Coraco-brachialis
INTERNAL
CUTANEOUS NERVE
Brachial artery
MEDIAN NERVE
Cephalic vein
MUSCULO-
CUTANEOUS
NERVE
Supinator longus
Radial vein
Median vein
Radial artery

560
THE ARTERIES
radius, into the radial and ulnar arteries. The artery is situated at first internal to
the humerus; but as it passes down the arm it gradually gets in front of the bone,
and at the bend of the elbow lies midway between the two condyles (fig. 350).
Hence, in controlling hæmorrhage, the artery should be compressed outwards
against the bone in its upper third, outwards and backwards in its middle third,
and directly backwards in its lower third. Throughout the greater part of its
course the artery is superficial, being merely overlapped slightly on its outer side
by the coraco-brachialis and biceps muscles; but at the bend of the elbow it sinks
deeply beneath the semilunar fascia of the biceps into the triangular interval,
bounded on either side by the supinator longus and pronator radii teres, and at its
FIG. 351.-THE BRACHIAL ARTERY AT THE BEND OF THE ELBOW.
POSTERIOR BRANCH
OF INTERNAL
CUTANEOUS NERVE
ANTERIOR BRANCH
OF INTERNAL
CUTANEOUS NERVE
BRANCH OF
MUSCULO-SPIRAL
NERVE TO
SUPINATOR LONGUS
RADIAL NERVE
BRANCH TO
PRONATOR TERES
Bicipital fascia, cut,
Radial recurrent artery
and POSTERIOR
INTEROSSEOUS
NERVE
MUSCULO-
CUTANEOUS NERVE
MEDIAN NERVE
bifurcation is more or less under cover of these muscles (fig. 351). A line drawn
from midway between the folds of the axilla at the outer side of that space to
midway between the condyles of the humerus, will indicate its course. It is
accompanied by two veins which frequently communicate across the artery.
Relations. In front, the artery is covered by the integuments and superficial and
deep fasciæ, and at the bend of the elbow by the semilunar fascia of the biceps, and in
muscular subjects by the overlapping margins of the supinator longus and pronator
radii teres. In the middle third of the arm it is crossed obliquely from without
inwards by the median nerve, and at the bend of the elbow by the median basilic
vein, the bicipital fascia intervening (fig. 357).
Behind, it lies successively on the long head of the triceps (from which it is

BRACHIAL
561
separated by the musculo-spiral nerve and superior profunda artery), on the inner
head of the triceps, on the insertion of the coraco-brachialis, and thence to its
bifurcation on the brachialis anticus muscle.
External to the artery is the coraco-brachialis above, and the muscular belly of
the biceps below, both of which slightly overlap the vessel, and at the bend of the
elbow the tendon of the biceps. The external vena comes is also to its outer side.
The median nerve is in close contact with the outer side of the artery in the upper
third of its course, but in the middle third crosses the artery obliquely to gain the
inner side.
Internal to the artery in the upper part of its course are the internal cutaneous
and the ulnar nerves; the latter nerve, however, leaves the artery about the origin
of the inferior profunda branch, to make, with that vessel, for the internal condyle.
Lower down, the internal cutaneous nerve also leaves the artery, by piercing the
deep fascia. The median nerve is in close contact with the inner side of the artery
in its lower third and at the bend of the elbow. The basilic vein is superficial to it,
and a little to its inner side in the greater part of its course, but separated from
it by the deep fascia. The internal vena comes runs along its inner side.
The Variations in the Brachial Artery

The chief variations in the brachial artery are:-(1) A high division into its terminal
branches. The high division may occur at any spot in the normal course of the vessel, but
is most common in the upper third of the arm, and least common in the middle third. The
two vessels into which the brachial then divides as a rule run parallel to each other to the
bend of the elbow in the usual situation of the brachial, whence one follows the normal
course of the radial artery through the forearm, and the other takes the normal course of
the ulnar artery, giving off as usual the common interosseous artery. This arrangement
may be considered a simple high division of the brachial. At other times the disposition of
the two vessels is different: thus (i) the two arteries may communicate at the elbow by a
cross branch, or reunite, and then again divide in the usual manner. (ii) One vessel may
follow the course of the ulnar artery in the forearm, and the other divide into the radial and
common interosseous. This condition is spoken of as a high origin of the ulnar. (iii) One
artery may divide into the radial and ulnar as usual, and the other take the course of the
common interosseous and divide into the anterior and posterior interosseous arteries; or,
much more rarely, take the course of the posterior interosseous artery, the anterior inter-
osseous coming from the ulnar. (iv) The vessels may follow a course in the upper arm
different to that of the normal brachial. Thus (A) the branch representing the radial may
(a) cross over or under the other branch; (b) perforate the deep fascia above the elbow,
and run beneath the skin to its place in the forearm; or (c) pass behind the tendon of the
biceps. (B) The branch representing the ulnar may (a) run to the front of the inner condyle
with the median nerve, and thence reach its usual situation by descending from within
outwards beneath the fascia and pronator teres, or, more rarely, beneath some of the flexor
muscles, or merely beneath the skin; or (b) it may run with the ulnar nerve behind the
inner condyle, and thence beneath the muscles to its usual place in the forearm. (2) An
enlarged vas aberrans may be present. This is a long slender vessel, which arises from the
brachial usually near the origin of the superior profunda, and joins most commonly the
radial artery, or, more rarely, one of its branches, or the ulnar. It is said to be usually
present, though not admitting of complete injection, and to descend over the median nerve
to the biceps muscle. At times this vessel takes the place of the brachial; the median
nerve will then be found behind the artery. (3) The brachial may run with the median
nerve towards the inner condyle, where it then usually turns round a supracondyloid process
after the course normally taken by the artery in the Felida, in which it runs through a
supracondyloid foramen. Thence it descends to its normal situation beneath the pronator
teres, which then usually arises from a fibrous expansion from the process. (4) The brachial
may be covered by various muscular slips derived from the adjacent muscles. (5) Certain
abnormalities in the giving off of its collateral branches. These are referred to under each
branch.


BRANCHES OF THE BRACHIAL ARTERY
The branches of the brachial artery are:-(1) The superior profunda; (2) the
inferior profunda; (3) the anastomotica magna; (4) the nutrient; (5) the muscular;
and (6) the terminal branches--the radial and ulnar arteries.
00
562
THE ARTERIES
(1) THE SUPERIOR PROFUNDA ARTERY
The superior profunda is the largest of the branches of the brachial. It arises
from the inner and hinder aspect of that artery, a little below the inferior border
of the tendon of the teres major. It at first lies to the inner side of the brachial,
but soon passes behind that vessel, and, sinking between the inner and long
heads of the triceps with the musculo-spiral nerve, curves round the humerus in
the musculo-spiral groove, lying in contact with the bone between the inner and
outer heads of the triceps. On reaching the external supracondyloid ridge of the
humerus, it perforates the external intermuscular septum, and, continuing forward
between the supinator longus and brachialis anticus to the front of the external
condyle, ends by anastomosing with the radial recurrent artery.
It gives off the following branches :-
(a) The ascending branch, which runs upwards in the substance of the triceps,
or between the outer and inner heads of that muscle, to anastomose with the
tricipital branch of the posterior circumflex artery. The importance of this
anastomosis in carrying on the collateral circulation after ligature of the third part
of the axillary artery below the circumflex, or the brachial above the profunda,
has already been mentioned (page 558).
(b) The cutaneous branch, which runs with the external cutaneous branch of
the musculo-spiral nerve to supply the skin of the outer side of the arm.
(c) The articular branch, which is often larger than the continued trunk of the
superior profunda itself, is given off from the artery just before it perforates the
intermuscular septum, runs downwards in the substance of the triceps to the back
of the external condyle, where it anastomoses with the interosseous recurrent, and
forms an arterial arch by anastomosing with the anastomotica magna across the back
of the lower end of the humerus immediately above the olecranon fossa. From
this arch or rete small twigs enter and supply the elbow joint.
(d) A nutrient artery is sometimes given to the upper end of the humerus.
(e) Muscular branches to the triceps.
Chief variations.-The superior profunda may arise (a) from the axillary artery in
common with one or more branches of that vessel; or (b) as a common trunk with the
inferior profunda. (c) It may give off the posterior circumflex, which then runs upwards
behind the teres major to reach the back of the shoulder.
(2) THE INFERIOR PROFUNDA ARTERY
The inferior profunda arises from the inner side of the brachial, usually
about the level of the insertion of the coraco-brachialis, at times as a common
trunk with the superior profunda. It passes with the ulnar nerve obliquely down-
wards and inwards through the internal intermuscular septum, and then along the
inner head of the triceps to the back of the internal condyle where, under cover of
the deep fascia and the origin of the flexor carpi ulnaris from the olecranon and
internal condyle, it anastomoses with the posterior ulnar recurrent and anasto-
motica magna arteries. It frequently supplies the nutrient artery to the humerus.
It gives branches to the triceps, to the elbow joint, and a branch which passes in
front of the internal condyle to anastomose with the anterior ulnar recurrent.
Chief variations. (1) The inferior profunda may arise (a) with the superior profunda;
(b) from a trunk common to several other branches of the axillary and brachial arteries.
(2) It may be absent, its place being taken by the anastomotica magna.
(3) THE ANASTOMOTICA MAGNA ARTERY
The anastomotica magna arises from the inner side of the brachial, about two
inches above its bifurcation into the radial and ulnar arteries, and, running down-
BRACHIAL-ULNAR
563
wards and inwards across the brachialis anticus, divides into two branches, a posterior
and an anterior. The posterior pierces the internal intermuscular septum, winds
round the internal condyloid ridge of the humerus, and pierces the triceps, between
which and the bone it anastomoses with the articular branch of the superior
profunda artery, and to a lesser extent with the interosseous recurrent, forming
an arterial arch or rete round the upper border of the olecranon fossa. The
anterior branch passes downwards and inwards between the brachialis anticus and
pronator teres, and anastomoses in front of the internal condyle, but beneath the
pronator teres with the anterior ulnar recurrent. From this branch a small vessel
passes down behind the internal condyle to anastomose with the posterior ulnar
recurrent and inferior profunda arteries.
Chief variations.-(a) The anastomotica magna may take the place of the inferior pro-
funda. (b) It may be very small, the inferior profunda taking its place.
(4) THE NUTRIENT ARTERY OF THE HUMERUS
The nutrient artery of the humerus comes off from the brachial about the
level of the insertion of the coraco-brachialis, or from the inferior profunda, or
from one of the muscular branches. It passes obliquely downwards through the
nutrient foramen, and on entering the medullary canal of the humerus divides
into an ascending and descending branch, of which the latter is the larger.
(5) THE MUSCULAR BRANCHES OF THE BRACHIAL
The muscular branches are irregular in their number, origin, and distribu-
tion. They vary from about five to eight, usually come off from the outer part of
the artery, and are distributed to the coraco-brachialis, biceps, and brachialis
anticus muscles. The nutrient artery of the humerus frequently arises from the
uppermost muscular branch.
THE ULNAR ARTERY
The ulnar artery, the larger of the two terminal branches of the brachial, begins
opposite the lower border of the head of the radius in the middle line of the fore-
arm. Thence through the upper half of the forearm it runs in a slight curve, with its
convexity inwards, deeply beneath the pronator teres and superficial flexor muscles,
and, having reached the ulnar side of the limb about midway between the elbow
and the wrist, it passes directly downwards, being merely overlapped by the flexor
carpi ulnaris. Crossing the annular ligament immediately to the radial side of the
pisiform bone, it enters the palm, where it divides into two branches, which enter
respectively into the formation of the superficial and deep palmar arches. The
artery is accompanied by two veins, which anastomose with each other by frequent
cross branches, and usually terminate in the brachial venæ comites; or sometimes
the inner vena comes ends in the inner brachial vein, the outer vena comes in the
median profunda vein. The ulnar nerve is at first some distance from the artery,
but approaches the vessel at the junction of its upper and middle thirds, and then
lies close to its inner or ulnar side. The course of the artery in the lower two-thirds
of the forearm is indicated by a line drawn from the front of the internal condyle
to the radial side of the pisiform bone; and in the upper third of the forearm by
a line drawn in a gentle curve with its convexity inwards from an inch below the
centre of the bend of the elbow to a point in the former line at the junction of its

002

564
THE ARTERIES
upper with its middle third. The artery throughout its course is best reached
through the innermost intermuscular septum, i.e. the interval between the flexor
carpi ulnaris, and the flexor sublimis digitorum.
The relations of the artery will be given in detail-as it lies in the forearm, at
the wrist, and in the palm of the hand.
FIG. 352.-THE ARTERIES OF THE FOREARM WITH THE DEEP PALMAR ARCH.
Inferior profunda artery
Anastomotica magna artery
Brachial artery
Radial recurrent artery
Anterior ulnar recurrent
Posterior ulnar recurrent
Supinator longus
Radial artery on flexor longus-
pollicis
Anterior interosseous artery
Flexor carpi ulnaris
Collateral branch of
palmar digital artery
Anterior interosseous artery
-Anterior branch of ulnar
artery
Deep palmar arch
Palmar digital artery, cut
short
I. RELATIONS OF THE ULNAR ARTERY IN THE FOREARM
In front. In the upper half of the forearm the ulnar artery is deeply placed
beneath the pronator teres, the flexor carpi radialis, the palmaris longus, and the
flexor sublimis digitorum. In the lower half it is comparatively superficial, being
200
ULNAR
565
merely overlapped above by the tendon of the flexor carpi ulnaris, whilst the last inch
or so of the vessel is only covered as a rule by the skin and superficial and deep fasciæ.
As the artery lies beneath the pronator teres, it is crossed from within outwards by
the median nerve, the deep head of origin of the muscle usually separating the
nerve from the artery. The lower part of the artery is crossed by the palmar
cutaneous branch of the ulnar nerve.
Behind. For about an inch of its course the artery lies upon the brachialis
anticus; but thence, as far as the anterior annular ligament of the wrist, upon the
flexor profundus digitorum, which separates it above from the interosseous membrane
and bone, and at the wrist from the pronator quadratus. The artery is bound down
to the flexor profunda digitorum by bands of fasciæ.
To the outer side in the lower two-thirds of its course is the flexor sublimis
digitorum.
To the inner side in the lower two-thirds is the flexor carpi ulnaris, the guide
to the vessel. The ulnar nerve, as it enters the forearm from behind the inner
condyle, is at first some distance from the artery, being separated from it in its
upper third by the flexor sublimis digitorum, but in its lower two-thirds is in close
contact with the vessel and on its ulnar side.
Variations of the Ulnar Artery in the Forearm
The principal variations of the ulnar artery in the forearm are: (A) It may arise from
the brachial above the usual point of division or from the axillary, in which case it usually
runs over the flexor muscles, but beneath the fascia, to reach its usual situation in the
forearm. The recurrent arteries and the common interosseous are then usually derived
from the trunk vessel from which the ulnar is given off. At times it runs beneath the
muscles, or merely beneath the skin. (B) It may in some cases of high division of the
brachial run beneath the fascia throughout its whole extent in the forearm. (C) In some
cases of normal origin from the brachial it takes a superficial course in the forearm,
being merely covered by the fascia, the recurrent branches and the common interosseous
then arising from the radial.



The branches of the ulnar artery in the forearm are:-1. The anterior ulnar
recurrent. 2. The posterior ulnar recurrent. 3. The interosseous, or common
interosseous: (a) anterior interosseous-(i) arteria comes nervi mediani, (ii)
muscular, (iii) medullary, (iv) anterior communicating; (b) posterior interosseous
-(i) interosseous recurrent, (ii) muscular, (iii) articular. 4. Muscular. 5. Nutrient.
6. Posterior ulnar carpal. 7. Anterior ulnar carpal.
1. The anterior ulnar recurrent is a small branch which leaves the inner
side of the ulnar artery soon after its origin, and, running upwards and inwards
between the outer edge of the pronator teres and the brachialis anticus, anastomoses
in front of the internal condyle with the anastomotica magna and a branch of the
inferior profunda artery. It supplies branches to the muscles between which it

runs.
2. The posterior ulnar recurrent, larger than the anterior ulnar recurrent, comes
off from the inner side of the ulnar artery, either a little below the latter branch,
or else as a common trunk with it, and, passing inwards between the flexor sublimis
and flexor profundus digitorum, turns upwards to the back of the internal condyle,
where it lies with the ulnar nerve beneath the two heads of origin of the flexor
carpi ulnaris. It supplies the contiguous muscles-the flexor carpi ulnaris, the
palmaris longus, and the flexor sublimis and profundus digitorum-the elbow joint
and the ulnar nerve, and anastomoses with the inferior profunda, with the anasto-
motica magna, and with the interosseous recurrent, forming the so-called rete
olecrani.
3. The interosseous or common interosseous artery, is a short thick trunk half an
inch or so in length, which comes off from the outer and back part of the ulnar about
566
THE ARTERIES
an inch from its origin, and just before the ulnar artery is crossed by the median
nerve. It passes backwards and downwards between the flexor longus pollicis and
the flexor profundus digitorum, towards the triangular interval bounded by the
upper border of the interosseous membrane, the oblique ligament, and the outer
border of the ulna, where it divides into the anterior and posterior interosseous
arteries.
(a) The anterior interosseous artery, smaller than the posterior, but apparently
the direct continuation of the common trunk, courses downwards in front of the
interosseous membrane, upon which it lies under cover of the overlapping edges.
of the flexor profundus digitorum and flexor longus pollicis, to the upper border
of the pronator quadratus, where it terminates in two branches, an anterior
terminal and posterior terminal.
The anterior interosseous artery is accompanied by two veins and by the deep
branch of the median nerve which lies to its radial side. The artery is bound down
to the interosseous membrane by aponeurotic fibres.
The branches of the anterior interosseous artery are:-(i) The arteria
comes nervi mediani-or the median artery as it is sometimes shortly called-is a
long slender vessel, which arises from the anterior interosseous immediately after
the latter is given off from the common trunk. It passes forwards between the
flexor profundus digitorum and the flexor longus pollicis to the median nerve, with
which it descends beneath the annular ligament into the palm, and when of large
size sometimes enters into the formation of the superficial palmar arch. At times
the artery arises from the common interosseous before its division. (ii) Muscular
branches supply the flexor longus pollicis, flexor profundus digitorum, and pronator
quadratus, and the extensor muscles of the thumb, which they reach by passing
backwards through the interosseous membrane. (iii) The nutrient arteries of the
radius and ulna are usually derived from this vessel. (iv) The anterior terminal
and smaller division of the anterior interosseous artery, sometimes called the
anterior communicating, passes either in front of or behind the pronator quadratus,
but in either case in front of the interosseous membrane, and anastomoses with
the anterior carpal branches of the radial and ulnar arteries, and with the recur-
rent branches from the deep palmar arch, forming the so-called anterior carpal
rete. (v) The posterior terminal and larger division pierces the interosseous
membrane, and continues its course downwards behind the interosseous membrane,
under cover of the extensor muscles, to the back of the wrist, where it ends
by anastomosing with the posterior carpal branches of the radial and ulnar
arteries, forming the so-called posterior carpal rete. This branch anastomoses,
as soon as it pierces the interosseous membrane, with the posterior interosseous
artery.
(b) The posterior interosseous artery, the larger division of the common
interosseous, turns backwards through the triangular interval bounded by the
interosseous membrane below, the oblique ligament above, and the ulna internally,
and, emerging at the back of the forearm between the extensor ossis metacarpi pollicis
and the supinator brevis, under cover of the superficial extensors of the forearm,
descends between the superficial and the deep muscles, crossing in this course the
extensor ossis metacarpi pollicis, the extensor primi internodii pollicis, the extensor
secundi internodii pollicis, and the indicator (fig. 353). It anastomoses at the
lower border of this muscle with the anterior interosseous, or with the posterior
branch of the anterior interosseous which here, as above described, has perforated
the interosseous membrane.
It gives off the following branches :-(i) The interosseous recurrent, or pos-
terior interosseous recurrent (fig. 353), arises from the posterior interosseous as the
latter emerges from beneath the supinator brevis. It runs upwards between the anco-
neus and supinator brevis, usually under cover of the former, to the interval between

PAULNAR
567
the external condyle and the olecranon, where it anastomoses with the superior
profunda, anastomotica magna, radial recurrent, and posterior ulnar recurrent
FIG. 353.--THE BACK OF THE FOREARM, WITH THE POSTERIOR INTEROSSEOUS ARTERY
AND BRANCHES OF THE RADIAL AT THE BACK OF THE WRIST.
(From a dissection in the Hunterian Museum.)
Articular branch of superior.
profunda
Brachialis anticus-
Supinator longus-
Triceps
Common extensor tendon-
Rete over olecranon
Interosseous recurrent artery
-Anconeus, cut
Extensor carpi radialis longior
and brevior
Supinator brevis
Posterior interosseous artery
Extensor ossis metacarpi pollicis
Extensor carpi radialis longior
Extensor primi internodii
pollicis
-Extensor carpi ulnaris
-Flexor carpi ulnaris
Origin of extensor secundi and
indicator
Posterior branch of anterior
interosseous artery
-Interosseous membrane
Posterior annular ligament
Extensor carpi radialis longior
Radial artery
Dorsalis pollicis artery
Extensor secundi internodii
pollicis
First dorsal interosseous muscle
Dorsalis indicis artery
Princeps pollicis artery
-Posterior ulnar carpal artery
-Extensor carpi radialis brevior
-Posterior radial carpal artery
-Third dorsal interosseous artery
-Second dorsal interosseous artery
-Metacarpal or first dorsal
interosseous artery
Dorsal digital artery
arteries, and gives branches to the retiform plexus over the olecranon-the rete
olecrani. (ii) Muscular branches are given off to the superficial and deep extensor
muscles. (iii) Articular branches enter the back of the wrist joint.
4. The muscular branches of the ulnar artery supply the contiguous muscles,
and are variable in number, origin, and distribution.

568
THE ARTERIES
5. The nutrient artery of the ulna may be given off from the main trunk of the
ulnar artery, or from one of its muscular branches, or from the anterior inter-
osseous artery.
6. The posterior ulnar carpal comes off from the ulnar artery a little above
the anterior annular ligament, and, winding inwards round the end of the ulna
or the internal lateral ligament of the wrist, beneath the flexor carpi ulnaris,
ramifies on the back of the carpus beneath the extensor tendons. It forms by
its anastomosis with the posterior radial carpal and with the posterior branch of
the anterior interosseous and with the posterior interosseous arteries, a plexus
or rete, the so-called posterior carpal arch. The branches given off from this
plexus or arch are described with the posterior carpal branch of the radial artery
(page 574).
7. The anterior ulnar carpal is a small branch given off from the ulnar artery
opposite the carpus. It passes beneath the flexor profundus digitorum to anasto-
mose with the anterior radial carpal, with terminal twigs of the anterior branch of
the anterior interosseous, and with recurrent branches from the deep palmar arch,
forming an anastomotic arch across the front of the carpus-the so-called anterior
carpal arch or rete.
II. RELATIONS OF THE ULNAR ARTERY AT THE WRIST
The ulnar artery at the wrist may be said to extend from the upper to the lower
border of the anterior annular ligament. It here lies immediately to the radial side
of the pisiform bone, and to the ulnar side of the hook of the unciform, the two bones
forming for the vessel a protecting channel, which is further converted into a short
canal by the expansion of the flexor carpi ulnaris passing from the pisiform to the
hook of the unciform. The ulnar nerve in this situation is immediately to the ulnar
side of the artery.
Relations. In front, it has, in addition to the expansion above mentioned, the
skin and superficial fascia; below, it rests on the annular ligament; internally are
the ulnar nerve and pisiform bone; externally, the hook of the unciform.
The ulnar artery gives off no named artery in this part of its course.
III. RELATIONS OF THE ULNAR ARTERY IN THE PALM
(SUPERFICIAL PALMAR ARCH)
The ulnar artery, on entering the palm, divides into two branches, the superficial
and deep.
The superficial branch (fig. 354), the direct continuation of the vessel, anastomoses
with the superficial volar, a branch of the radial, forming what is then known as
the superficial palmar arch. After descending a short distance towards the cleft
between the fourth and fifth fingers, it turns outwards towards the thumb, forming
a curve with its convexity towards the fingers and its concavity towards the muscles
of the thumb, and anastomoses opposite the cleft between the index and middle
fingers, at the junction of the upper with the middle third of the palm, with the
superficial volar branch of the radial artery to complete the arch. A line drawn
across the palm on a level with the thumb at a right angle to the hand will
roughly indicate the situation of the arch.
Relations. In front: in addition to the skin and superficial fascia, the vessel
is crossed successively, from within outwards, by the palmaris brevis, the palmar
branch of the ulnar nerve, the palmar fascia, and the palmar branch of the median

nerve.

SUPERFICIAL PALMAR ARCH
569
Behind, it rests upon, from within outwards, the short muscles of the little finger,
the digital branches of the ulnar nerve, the flexor tendons, and the digital branches
of the median nerve.
Variations in the Superficial Palmar Arch
The superficial palmar arch is very subject to variations. (A) It may be formed by
the superficial branch of the ulnar anastomosing with the radialis indicis, or with the radial
FIG. 354.-ANASTOMOSES AND DISTRIBUTION OF THE ARTERIES OF THE HAND.
Anterior interosseous
Radial artery
Anterior radial carpal
Superficial volar
Posterior radial carpal.
Radial artery at wrist.
Dorsalis pollicis-
Metacarpal or first-
dorsal interosseous
Princeps pollicis
Dorsalis indicis
Ulnar artery
-Anterior ulnar carpal
-Posterior ulnar carpal
-Deep ulnar
-Superficial arch
-Carpal recurrent
Posterior communicating
or perforating
Radialis indicis.
Dorsal digital
Collateral digital-
First dorsal branch of-
collateral digital
Second dorsal branch of-
collateral digital
Palmar interosseous
Second, third, and fourth
palmar digital
Second and third dorsal
interosseous
First palmar digital
Anterior communicating
or perforating
Anastomosis of collateral.
digital arteries about
matrix of nail and pulp
of finger
in the palm instead of with the superficial volar branch of the radial. (B) The superficial
volar may be larger than usual, and take a greater share than the ulnar in the formation
of the arch. (C) The arch may be reinforced by a large median artery, or by an enlarged
interosseous artery. (D) The arch may be double, both the superficial branch of the
ulnar and the superficial volar dividing into two branches which anastomose across the
palm. (E) The arteries of the thumb and radial side of the index finger may be given
off from the arch. (F) The arch may be incomplete, the outer digital branches coming

570
THE ARTERIES
off from the ulnar, and the inner from the superficial volar, the radial in the palm or an
enlarged median artery. (G) The arch may be absent, the lateral digital arteries being
then given off from enlarged interosseous arteries from the deep arch, or from enlarged
dorsal interosseous arteries.
The branches of the superficial palmar arch are:-(1) The four digital
arteries; (2) the muscular; and (3) the cutaneous.
FIG. 355.-THE ARTERIES OF THE FOREARM AND THE DEEP PALMAR ARCH.
Inferior profunda artery
Anastomotica magna artery
Brachial artery
Radial recurrent artery-
-Anterior ulnar recurrent
-Posterior ulnar recurrent
Supinator longus
-Anterior interosseous artery
-Flexor carpi ulnaris
Radial artery
-Anterior interosseous artery
Collateral branch of palmar digital-
artery
-Anterior branch of ulnar artery
-Deep palmar arch
-Palmar digital artery, cut short
(1) The digital arteries, usually four in number, are given off from the convexity
of the superficial arch and, running downwards through the palm, supply both sides
of the little, ring, and middle fingers, and the ulnar side of the index finger. The
radial side of the index finger and the thumb are supplied respectively by the radialis
indicis and princeps pollicis, branches of the radial artery. The digital arteries are
ULNAR-RADIAL
571
named, from within outwards-first, second, third, and fourth. The first digital
artery runs downwards and inwards over the muscles on the inner side of the palm,
and thence along the ulnar side of the little finger. It gives branches to the
abductor, flexor brevis, and opponens minimi digiti muscles. This branch some-
times comes from the deep branch of the ulnar artery. The second, third, and
fourth digital arteries run downwards in the interspace between the little and ring,
the ring and middle, and the middle and index fingers respectively, to within about
a quarter of an inch of the clefts between the fingers, where they divide into two
branches (collateral digital) for the supply of the sides of the contiguous fingers.
As the digital arteries pass through the palm, they lie between the flexor tendons,
on the digital nerves and lumbrical muscles, and beneath the palmar fascia. Just
before bifurcating they pass under the superficial transverse ligament, and are
joined by the palmar interosseous branches from the deep palmar arch (fig. 354).
At this spot they also receive the anterior perforating branches from the dorsal
interosseous vessels. On the sides of the fingers the collateral digital arteries lie
between the palmar and dorsal digital nerves. They anastomose by small branches,
forming an arch across the front of the bones on the proximal side of each inter-
phalangeal joint. They supply the flexor tendons and the integuments, and
terminate in a plexiform manner beneath the pulp of the finger and around the
matrix of the nail. A dorsal digital branch is given off to the back of the fingers
about the level of the middle of the first phalanx, and a second but smaller dorsal
digital branch about the level of the middle of the second phalanx.
(2) The muscular branches from the superficial arch are very small and supply
the superficial muscles.
(3) The cutaneous branches supply the integuments of the palm.
The deep branch of the ulnar artery, also called the communicating artery,
sinks deeply into the palm between the abductor and flexor brevis minimi digiti,
and joins the radial to form the deep palmar arch. (See THE RADIAL ARTERY,
page 576.)
THE RADIAL ARTERY
The radial artery-the smaller of the two arteries into which the brachial divides
at the bend of the elbow-appears as the direct continuation of the brachial. It
runs downwards and outwards along the radial side of the forearm as far as the
styloid process, then, coiling over the external lateral ligament and outer and back
part of the wrist, enters the palm of the hand from behind between the first and
second metacarpal bones, and ends by anastomosing with the deep branch of the
ulnar to form the deep palmar arch. Hence the artery is divisible into three parts:
that in the forearm, that at the wrist, and that in the palm of the hand.

I. THE RADIAL ARTERY IN THE FOREARM
In its course through the forearm (fig. 351) the radial artery is found in the
outermost intermuscular space, and it is only necessary to divide the skin, super-
ficial and deep fascia, to expose the vessel, and in addition in the upper third to
separate the supinator longus (humero-radialis) from the pronator radii teres.
In front, the artery is at first overlapped by the supinator longus, but for the
rest of its course it is merely covered by the skin, superficial and deep fascia, by
some cutaneous veins, and by cutaneous branches of the musculo-cutaneous nerve.
Behind, it lies successively from above downwards on the tendon of the biceps, the
supinator brevis, the insertion of the pronator radii teres, the radial origin of the flexor
sublimis digitorum, the flexor longus pollicis, the pronator quadratus, and the front
surface of the lower end of the radius. It is in this last situation, where the artery

572
THE ARTERIES
lies upon the bone and can therefore be easily pressed against it, that the pulse is
usually felt.
On its outer side it has, throughout the whole of its course, the supinator
longus or humero-radialis muscle, the guide to the artery in ligature, and the
external vena comes; in its middle third, the radial nerve as well. In its lower
third the radial nerve is to its outer side, but separated from it by the supinator
longus and fascia.
FIG. 356.-DIAGRAM OF THE RELATION OF THE ARTERIES OF THE FOREARM
TO THE BONES.
Inferior profunda artery
Brachial artery-
Superior profunda artery
Anastomotica magna-
artery
Anterior ulnar recurrent-
Posterior ulnar recurrent-
Ulnar artery
Common interosseous
artery
EXTERNAL CONDYLE
Articular branch of
superior profunda
artery
Radial recurrent artery
Interosseous recurrent
artery
Radial artery
Oblique ligament
Anterior interosseous
artery
Posterior interosseous
artery
Anterior ulnar carpal-
Superficial branch of
ulnar artery (superficial
palmar arch)
First palmar digital.
artery
Deep palmar arch
Anterior radial carpal
Radial artery at wrist
Superficial volar branch
of radial artery
On its inner side, in the upper third is the pronator radii teres, in the lower
third the tendon of the flexor carpi radialis, and throughout the whole of its course
the internal vena comes.
Variations in the Radial Artery in the Forearm
(A) The radial artery may be given off from the brachial higher than usual, or from the
axillary artery. (B) It may arise from the brachial lower than the bend of the elbow,
but a low division of the brachial is rare. (C) It may run superficial to the fascia of
the forearm. (D) It may cross over, instead of under, the extensors of the thumb. (E) It

RADIAL
573
may terminate in the forearm or be absent, its place in the forearm and hand being then
supplied by the ulnar, the anterior interosseous, or an enlarged median artery. (F) It may
be joined by a vas aberrans from the brachial or axillary artery.
The branches of the radial artery in the forearm are:-(1) The radial recurrent;
(2) the muscular; (3) the anterior radial carpal; (4) the superficial volar.
(1) The radial recurrent usually arises from the outer side of the radial just
below its origin from the brachial. It at first runs outwards on the supinator brevis,
and then divides into three chief branches (fig. 357). One of these runs transversely
FIG. 357.-THE BEND OF THE ELBOW.
(From a dissection by Dr. Alder Smith in the Museum of St. Bartholomew's Hospital.)
Biceps
MEDIAN NERVE
Anastomotica magna.
BRANCHES
OF INTERNAL
CUTANEOUS NERVE
Posterior ulnar vein-
Brachialis anticus-
Anastomotica magna-
artery
Anterior ulnar vein-
Median basilic vein
MUSCULAR BRANCH-
OF MEDIAN NERVE
Tendon of biceps-
Bicipital fascia
Brachialis anticus
Deep median vein
Ulnar artery
Pronator teres
Basilic vein
Brachialis
anticus
Cephalic vein
Brachial artery
EXTERNAL
CUTANEOUS
NERVE
Musculo-spiral n.
and ascend. br. of
radial recur. art.
Radial vein
Median cephalic
vein
Ascending br. of
radial recurrent
RADIAL
NERVE
Radial recurrent
artery
Supinator
longus
Descending br. of
radial recurrent
Median vein
RADIAL
NERVE
Radial artery.
outwards through the fibres of the musculo-spiral nerve, or between the radial and
posterior interosseous nerves when the musculo-spiral divides higher than usual,
into the supinator longus and extensor carpi radialis longior and brevior, and ana-
stomoses with the interosseous recurrent. A second ascends between the brachialis
anticus and supinator longus, with the musculo-spiral nerve, and anastomoses
with the superior profunda artery. A third descends with the radial nerve under
cover of the supinator longus supplying that muscle. The radial recurrent also
gives off branches to the elbow joint.
574
THE ARTERIES
(2) The muscular branches of the radial artery come off irregularly to supply the
contiguous muscles on the outer side of the forearm.
(3) The anterior radial carpal arises from the inner side of the radial artery
about the level of the lower border of the pronator quadratus. It crosses the front
of the radius beneath the flexor muscles, and anastomoses with the anterior carpal
branch of the ulnar, forming what is sometimes called the anterior carpal arch; or
what is, more properly speaking, an arterial plexus or rete the anterior carpal rete.
This plexus is joined above by small twigs from the anterior interosseous artery,
and below by recurrent branches from the deep palmar arch. It supplies branches
to the lower end of the radius, and to the wrist and carpal joints.
(4) The superficial volar leaves the radial artery as the latter vessel is about
to turn over the external lateral ligament to the back of the wrist. It courses
forwards over the short muscles of the ball of the thumb, and anastomoses with
the superficial branch of the ulnar artery to complete the superficial palmar arch.
It supplies small branches to the muscles of the ball of the thumb, and at times
terminates in these muscles without joining the arch. Occasionally it passes beneath
the abductor pollicis.
II. THE RADIAL ARTERY AT THE WRIST
The radial artery at the wrist winds over the outer side of the carpus, under the
extensor tendons of the thumb, from a spot a little below and internal to the styloid
process of the radius to the base of the first interosseous space, where it sinks
between the two heads of the abductor indicis into the palm, to form, by anastomosing
with the deep branch of the ulnar artery, the deep palmar arch. A line drawn
from half an inch internal to the styloid process to the base of the first interosseous
space, which can be distinctly felt on the back of the hand, will roughly indicate
the course of the artery.
Relations. The artery is covered successively by the extensor ossis metacarpi
pollicis and extensor primi internodii pollicis, by branches of the radial nerve and
superficial radial veins, and, just before it sinks between the two heads of the
abductor indicis, by the tendon of the extensor secundi internodii pollicis. The
branches of the radial nerve to the thumb and index finger cross it. It is at first
somewhat deeply placed beneath the first-mentioned extensor muscles of the thumb;
but subsequently it lies quite superficial, and can be felt pulsating in a little
triangular depression bounded on either side by the extensor primi and extensor
secundi internodii pollicis, and above by the lower end of the radius. The artery
lies successively on the external lateral ligament of the wrist, on the scaphoid, the
trapezium, the base of the first metacarpal bone, and on the dorsal ligaments
uniting these bones. It has usually with it two companion veins, and a few
branches of the musculo-cutaneous nerve.
The branches of the radial artery at the wrist are:-(1) The posterior radial
carpal; (2) the metacarpal, or the first dorsal interosseous; (3) the dorsalis pollicis,
or dorsal artery of the thumb; (4) the dorsalis indicis, or dorsal digital artery of the
first finger.
(1) The posterior radial carpal arises from the radial as the latter vessel passes
under the extensor ossis metacarpi pollicis, and runs inwards beneath the extensor
carpi radialis longior and brevior, and the extensor secundi internodii pollicis, across
the back of the carpus, to anastomose with the posterior ulnar carpal and with the
terminal twigs of the posterior branch of the anterior interosseous artery. This
anastomosis is called the posterior carpal arch, or posterior carpal rete. The two
following named branches are given off from this arch or rete:-(a) The second
and (b) the third dorsal interosseous arteries to the third and fourth spaces respec-
tively. These vessels run downwards on the dorsal interosseous muscles as far as


RADIAL AT THE WRIST.
575
the flexure of the fingers, and there divide into two branches (dorsal digital), which
run along the sides of the contiguous fingers on their dorsal aspect. Near their
proximal ends they anastomose with the posterior perforating branches of the
deep palmar arch. Distally they are connected by anterior perforating branches
FIG. 358. THE RADIAL ARTERY AT THE WRIST.
(From a dissection in the Hunterian Museum.)
Articular branch of superior
profunda
Brachialis anticus-
Supinator longus
Triceps
Common extensor tendon
kete over olecranon
Interosseous recurrent artery
-Anconeus, cut
Extensor carpi radialis longior
and brevior
Supinator brevis
Posterior interosseous artery
Extensor ossis metacarpi pollicis
Extensor carpi radialis longior
Extensor primi internodii
pollicis
Extensor carpi ulnaris
-Flexor carpi ulnaris
Origin of extensor secundi and
indicator
Posterior branch of anterior
interosseous artery
Interosseous membrane
Posterior annular ligament
Extensor carpi radialis longior
Radial artery
Dorsalis pollicis artery-
Extensor secundi internodii.
pollicis
First dorsal interosseous muscle-
Dorsalis indicis artery
Princeps pollicis artery
Posterior ulnar carpal artery
Extensor carpi radialis brevior
Posterior radial carpal artery
Third dorsal interosseous artery
Second dorsal interosseous artery
Metacarpal or first dorsal
interosseous artery
Dorsal digital artery
with the digital arteries of the corresponding spaces. The branches which run
along the backs of the fingers anastomose with the dorsal branches of the collateral
digital arteries derived from the palmar digital vessels (fig. 359).
(2) The metacarpal or first dorsal interosseous artery (figs. 358, 359) arises from

576
THE ARTERIES
the radial artery beneath the extensor secundi internodii pollicis, and, crossing the
second metacarpal bone, passes downwards on the second dorsal interosseous muscle
between the extensor tendons to the level of the metacarpo-phalangeal joint, where
it divides into two small branches, like the other dorsal interosseous arteries, for the
supply of the sides of the contiguous fingers on their dorsal aspect. At the base of
the second interosseous space it communicates with the posterior perforating branch
of the deep arch, which here runs forwards between the heads of the second dorsal
interosseous muscle, and at the fore part of the space it anastomoses through the
anterior perforating branch with the fourth digital artery.
The dorsal digital arteries, the terminations of the metacarpal artery and dorsal
interosseous arteries, extend along the sides of the fingers as far as the first inter-
phalangeal joint, where they anastomose with the dorsal branches of the collateral
digital arteries.
(3) The dorsalis pollicis arises from the radial just before it sinks between the
two heads of the first dorsal interosseous muscle. It runs downwards on the ulnar
side of the extensor secundi internodii pollicis, along the metacarpal bone, and
divides into two branches for the supply of the radial and ulnar side of the thumb on
its dorsal aspect. These branches sometimes come off separately from the radial
artery.
(4) The dorsalis indicis arises from the radial just as that artery sinks between
the two heads of the first dorsal interosseous muscle, usually below the origin of
the dorsalis pollicis, but sometimes as a common trunk with the latter vessel. It
runs downwards along the radial side of the metacarpal bone of the index finger,
and can be traced along the radial side of that finger as far as the first inter-
phalangeal joint, where it anastomoses with the dorsal branch of the radialis
indicis.
III. THE RADIAL ARTERY IN THE PALM (THE DEEP PALMAR ARCH)
The radial artery enters the palm between the first and second metacarpal bones
at the base of the first interosseous space, by passing between the two heads of the
first dorsal interosseous muscle. It then runs inwards between the adductor pollicis
and inner head of the flexor brevis pollicis, and continuing its course, in a slight curve
with the convexity forwards, across the base of the metacarpal bones and interos-
seous muscles, it anastomoses with the deep branch of the ulnar, forming the deep
palmar arch. The arch thus formed may be said to extend from the first inter-
osseous space to the base of the metacarpal bone of the little finger, and is a finger's
breadth nearer the wrist than the superficial arch. It is covered by the superficial
and deep flexor tendons, by the inner head of the flexor brevis pollicis, and by part of
the flexor brevis minimi digiti. It is accompanied by the deep branch of the ulnar
nerve, and two small venæ comites.

Variations in the Deep Palmar Arch

(A) The deep palmar arch may be larger than usual, and its interosseous branches
supply the place of one or more of the digital arteries by dividing at the cleft of the fingers
into collateral digital branches. (B) It may be reinforced by enlarged posterior perforating
branches from the radial and its branches on the back of the hand, or by a large anterior
interosseous. (C) The radial may join the deep arch by passing through the second
instead of the first interosseous space. (D) The princeps pollicis and radialis indicis may
come off from the superficial arch or from the superficial volar, or from a separate branch
of the radial which passes through the first interosseous space.
The branches of the deep palmar arch are:-(1) The princeps pollicis; (2) the
radialis indicis; (3) the palmar interosseous (three in number); (4) the recurrent
carpal; (5) the posterior perforating. The first two are usually spoken of as


DEEP PALMAR ARCH
577
coming off from the radial artery in the palm; the last three from the deep palmar
arch.
(1) The princeps pollicis arises from the radial artery as it enters the palm,
between the two heads of the abductor indicis. It passes downwards between the
adductor pollicis and abductor indicis, parallel to the metacarpal bone, and between
the two portions of the flexor brevis pollicis under cover of the flexor longus pollicis.
FIG. 359.-ANASTOMOSES AND DISTRIBUTION OF THE ARTERIES OF THE HAND.
Anterior interosseous
Radial artery
Anterior radial carpal
Superficial volar
Posterior radial carpal
Radial artery at wrist.
Dorsalis pollicis
Metacarpal or first-
dorsal interosseous
Princeps pollicis
Dorsalis indicis
Ulnar artery
Anterior ulnar carpal
-Posterior ulnar carpal
-Deep ulnar
-Superficial arch
-Carpal recurrent
Posterior communicating
or perforating
Radialis indicis.
Dorsal digital-
Collateral digital-
First dorsal branch of-
collateral digital
Second dorsal branch of-
collateral digital
Palmar interosseous
Second, third, and fourth
palmar digital
Second and third dorsal
interosseous
First palmar digital
Anterior communicating
or perforating
Anastomosis of collateral
digital arteries about
matrix of nail and pulp
of finger
Opposite the metacarpo-phalangeal joint it usually divides into two branches, one
of which is distributed to each side of the thumb, on its palmar aspect. These
vessels anastomose with each other at the end of the thumb, like the other collateral
digital arteries.
(2) The radialis indicis comes off from the radial artery a little lower than the
former vessel, or as a common trunk with it, and passes forwards between the
abductor indicis and adductor pollicis, parallel to the radial side of the second
PP

578
THE ARTERIES
metacarpal bone. After emerging from beneath the adductor pollicis, it continues its
course along the radial side of the index finger, on its palmar aspect, as far as the tip,
anastomosing in this course with the collateral digital artery on the opposite side of
FIG. 360.-THE ARCH OF THE AORTA, THE THORACIC AORTA, AND THE ABDOMINAL
AORTA, WITH THE SUPERIOR AND INFERIOR VENA CAVA AND THE INNOMINATE AND
AZYGOS VEINS.
Right common carotid.
artery
Right internal jugular
vein
RIGHT LYMPHATIC DUCT
Innominate artery
Right innominate vein.
Internal mammary vein.
Trunk of the pericardiac
and thymic veins
Vena cava superior
Vena azygos major
Left common carotid
artery
PNEUMOGASTRIC
NERVE
THORACIC DUCT
-Left innominate vein
Left subclavian artery
Left superior
intercostal vein
RECURRENT
LARYNGEAL
NERVE
Vena azygos minor, cross-
ing spine to vena azygos
major
Hepatic veins.
CESOPHAGUS
Left upper azygos vein
Vena azygos minor
THORACIC DUCT
Right phrenic artery.
Coeliac axis
Middle suprarenal.
artery
Left phrenic artery
Right spermatic artery
RECEPTACULUM CHYLI
-Superior mesenteric
artery
Left ascending lumbar
vein
Left spermatic vessels
-Inferior mesenteric
artery
the finger in a way similar to that of the other collateral digital arteries. It
frequently communicates, at the lower border of the adductor pollicis, with the
superficial palmar arch and princeps pollicis. It gives off a dorsal branch, which
anastomoses with the dorsalis indicis.

THORACIC AORTA
579
(3) The palmar interosseous arteries, three in number, come off from the con-
vexity of the deep arch, and, coursing downwards in the centre of the second, third,
and fourth interosseous spaces on the interosseous muscles, terminate near the clefts
of the fingers by anastomosing with the digital arteries from the superficial arch.
These vessels supply the interosseous muscles and the bones, and the second, third,
and fourth lumbricales.
(4) The recurrent branches come off from the concavity of the arch, and
consist of two or three small vessels which run upwards towards the wrist,
and anastomose above with the anterior branch of the anterior interosseous, and
laterally with the anterior radial and ulnar carpal arteries, forming the so-called
anterior carpal rete (fig. 359).
(5) The posterior, communicating, or perforating, also usually three in number,
pass from the arch directly through the second, third, and fourth interosseous spaces
between the two heads of the corresponding dorsal interosseous muscle, and join
the proximal ends of the metacarpal artery (first dorsal interosseous), and the
second and third dorsal interosseous arteries respectively.
THE DESCENDING, OR THORACIC AORTA
The thoracic aorta (fig. 360) extends from the termination of the aortic arch at
the lower border of the body of the fifth thoracic vertebra to the body of the twelfth
thoracic vertebra, where it passes through the aortic opening in the diaphragm, and
is thence continued under the name of the abdominal aorta. It is at first situated
a little to the left of the vertebral column, but as it descends approaches the front
of the column, at the same time following the backward curve of the spine, and at
its passage through the diaphragm is almost in the middle line. It lies in the
posterior mediastinum, having the oesophagus at first a little to the right of it, then
in front of it, and just above the tenth thoracic vertebra, where this tube pierces
the diaphragm, a little to its left side.
Relations. In front it is crossed from above downwards by the root of the
left lung, by the oesophagus which separates it from the pericardium and heart,
and by the diaphragm.
Behind, it lies upon the lower seven thoracic vertebræ, and is crossed obliquely
opposite the seventh or eighth vertebra by the vena azygos minor, and opposite the
fifth or sixth vertebra by the superior intercostal vein or third azygos vein, or by one
or more of the left intercostal veins.
On the right side it has, above, the oesophagus, and lower down the right pleura
and lung. The vena azygos major and thoracic duct also lie to the right, but
on a somewhat posterior plane.
On the left side it has the left lung and pleura above, and the oesophagus below.
The vena azygos minor and the third azygos vein are also to the left, but on a
posterior plane.

BRANCHES OF THE THORACIC AORTA
The branches of the thoracic aorta may be divided into the visceral and
the parietal. The visceral are:-(1) The pericardiac; (2) the bronchial; and
(3) the œsophageal. The parietal are:-(1) The intercostal; (2) the subcostal;
(3) the diaphragmatic; and (4) the arteria aberrans.
A. Visceral Branches
(1) The pericardiac-two or three small branches, irregular in their origin,
course, and distribution-pass to the posterior surface of the pericardium to supply
that structure, and anastomose with the other pericardiac branches. They give small
twigs to the posterior mediastinal glands.
PP 2

FIG. 361.-SCHEME OF THE THORACIC AORTA.
1. At level of fifth
thoracic vertebra.
Intercostal artery
Intercostal vein
Intercostal vein
FIFTH
THORACIC
VERTEBRA
Intercostal artery
Vena azygos major-
Left upper azygos vein
THORACIC DUCT
ESOPHAGEAL PLEXUS OF
RIGHT PNEUMOGASTRIC
NERVE
CESOPHAGUS
ESOPHAGEAL PLEXUS OF
LEFT PNEUMOGASTRIC
NERVE
2. At level of seventh
thoracic vertebra.
Intercostal artery
AORTA
Intercostal vein
SEVENTH
THORACIC
VERTEBRA
Intercostal artery
Vena azygos major
Intercostal vein
Vena azygos minor
PLEURA
THORACIC DUCT
AORTA
PLEURA
LUNG
RIGHT ESOPHAGEAL
PLEXUS
LEFT ESOPHAGEAL
PLEXUS
3. At level of ninth
thoracic verte bra.
PERICARDIUM
LUNG
CESOPHAGUS
Intercostal artery.
NINTH
THORACIC
Intercostal vein
Intercostal artery
Intercostal vein-
VERTEBRA
PLEURA
LUNG
Vena azygos major-
THORACIC DUCT-
AORTA
PLEURA
LUNG
Vena azygos minor
RIGHT PNEUMOGASTRIC
NERVE
CESOPHAGUS
LEFT PNEUMOGASTRIC
NERVE

THORACIC AORTA
581
(2) The bronchial arteries (fig. 324) supply the bronchi and the lung substance.
They vary considerably in their origin, course, and distribution; they are usually
three in number-one on the right side, and two on the left.
(a) The right bronchial generally arises either from the first right aortic inter-
costal, or else as a common trunk with the left upper bronchial from the front of
the thoracic aorta just below the level of the bifurcation of the trachea. It passes
outwards on the back of the right bronchus, and is distributed to the bronchi and
lung substance. (b) The left upper bronchial arises from the front of the thoracic
aorta just below the bifurcation of the trachea, or as a common trunk with the
right bronchial. (c) The left lower bronchial arises from the front of the thoracic
aorta just below the level of the left bronchus. Like the corresponding artery on
the right side, the left bronchial arteries run outwards on the left bronchus, and, after
dividing and subdividing on the back of the bronchi, supply the bronchi themselves
and the lung substance. Small twigs are given off from the bronchial arteries to
the bronchial glands and to the œsophagus.
(3) The œsophageal arteries, four or sometimes five in number, arise at intervals
from the front of the thoracic aorta, the first coming off just below the left lower
bronchial. They usually increase in size from above downwards, the upper coming
off more towards the right side of the aorta, the lower more towards the left side.
They pass forwards to the oesophagus, supplying that tube and anastomosing with
each other and with the descending œsophageal branches of the inferior thyroid
above, and with the ascending oesophageal branches of the phrenic and gastric
arteries below, thus forming a chain of anastomoses along the whole length of the
tube.

B. Parietal Branches

(1) The aortic intercostal arteries, usually ten in number on each side, supply
the lower intercostal spaces, the two upper spaces being supplied by the superior
intercostal branch of the subclavian artery. The tenth artery runs along the lower
border of the last rib, and would be better called the subcostal artery; it is similar
in its distribution to the other intercostals, but is described separately.
The aortic intercostals arise in pairs from the back part of the thoracic aorta, and
at once turning, the one to the right, the other to the left, wind backwards over the
front and sides of the vertebral bodies to reach the intercostal spaces, which they
follow, and anastomose in front with the anterior intercostals given off from the
internal mammary and musculo-phrenic arteries respectively. In foetal life these
arteries run almost transversely backwards, or even with a slight inclination down-
wards, to the intercostal spaces; but after the first year, in consequence of the dispro-
portionate growth of the aorta and vertebral column, the upper intercostals have to
ascend to reach their respective spaces. For convenience of description the inter-
costal arteries may be divided into two portions-the vertebral, which lies upon the
bodies of the vertebræ; and the intercostal, which lies in the intercostal spaces.
The vertebral portion. The arteries in their course round the vertebræ differ
on the two sides of the body. On the right side the arteries-and especially the
upper, in consequence of the aorta lying a little to the left side of the spine in the
upper part of its course-are longer than the left. They wind over the front and
right side of the vertebræ, being crossed by the thoracic duct and vena azygos
major, and covered by the right pleura and lung. The upper are also crossed by
the œsophagus. They give off small branches to the bodies of the vertebræ and
anterior common ligament. On the left side, as the intercostals wind round the
side of the bodies of the vertebræ, the lower are crossed by the vena azygos minor,
the two upper by the left superior intercostal vein, and the two next by the third
azygos vein when this is present. They are all covered by the left pleura and
lung.

582
THE ARTERIES
The intercostal portion.-In their course through the intercostal spaces the
arteries are alike on both sides. They at first cross the intercostal spaces obliquely,
in consequence of the downward direction of the ribs, towards the angle of the rib
above, and thence are continued forward in the subcostal groove, and anastomose with
the superior branches of the anterior intercostals from the internal mammary in
the upper spaces, and from the musculo-phrenic in the lower spaces. They lie at
first on the external intercostal muscles, being covered in front by the pleura and
lung, the endothoracic fascia and the infra-costales muscles. Opposite the heads
of the ribs they are crossed by the sympathetic nerve. At the angle of the ribs
they pass under cover of the internal intercostal muscles, and thence to their
termination lie between the two intercostal muscles. Their situation in the mid-
space as far as the angle of the rib should be remembered in performing paracentesis
thoracis. To avoid the risk of injuring the vessels, the puncture should not be made
further back than the angle of the ribs. They are accompanied by an intercostal
nerve and vein, the vein lying above and the nerve below, except in the upper
spaces where the artery, having to ascend to reach the space, at first lies below the
nerve which passes transversely outwards. The uppermost aortic intercostal artery
anastomoses with the superior intercostal from the subclavian, and at times sup-
plies almost entirely the second intercostal space. The arteries to the tenth and
eleventh spaces on reaching the end of their respective ribs pass between the
abdominal muscles, and anastomose with the deep epigastric artery from the
external iliac, and with the lumbar arteries from the abdominal aorta.
The intercostal arteries give off the following branches:-
(a) The dorsal branch. This large branch is given off from the intercostals
opposite the quadrilateral space bounded by the transverse process of the vertebra
above, the neck of the rib below, the body of the vertebra internally, and the superior
costo-transverse ligament externally. Passing backwards towards this space with
the dorsal branch of the corresponding intercostal nerve, the dorsal branch divides
opposite the intervertebral foramen into a spinal and a muscular branch. (i) The
spinal branch enters the intervertebral foramen along with the undivided trunk
of the intercostal nerve, and subdivides into three branches :-(a) an anterior or
preneural, which ramifies on the back of the body of the vertebra and anastomoses
with the corresponding vessels above and below; (3) a posterior, or retroneural,
which ramifies over the back of the spinal canal and also anastomoses with the like
artery above and below; and (c) a middle or medullary, which, passing inwards in the
sheath of dura mater to the spinal cord, anastomoses with the anterior spinal
artery in front, and with the posterior spinal artery behind. (ii) The muscular
branch passes backwards through the quadrilateral space, and soon subdivides
into an external and internal branch. The former passes between the longissimus
dorsi and ilio-costalis, and, after supplying these muscles, gives cutaneous offsets to
the integuments. The latter or internal branch pierces the multifidus spinæ, and,
emerging between the longissimus dorsi and semispinalis dorsi near the spinous
processes, gives cutaneous offsets to the skin. It supplies the muscles in its course.
(b) The collateral intercostal branch comes off from the intercostal artery
near the angle of the rib above, and descends to the upper border of the rib below,
along which it runs between the intercostal muscles to anastomose with the inferior
division of the anterior intercostal branch of the internal mammary artery. It is
much smaller than the main intercostal artery, and helps to supply the structures
in the intercostal space and neighbouring parts.
(c) The pleural branches ramify beneath the pleura, forming a plexus by
anastomosing with like branches above and below.
(d) The muscular branches supply the intercostals, serratus magnus, pectoralis
major and minor, and anastomose with the long and short thoracic branches of the
axillary artery.

THORACIC AORTA
583
(e) The lateral cutaneous branches run with the lateral cutaneous branches of
the intercostal nerves to the skin.
(f) The mammary glandular branches are given off from the intercostal arteries
in the third, fourth, and fifth intercostal spaces, and supply the mammary gland.
They are of large size during lactation, and generally require a ligature in the
removal of the breast.
(2) The subcostal artery, or the twelfth dorsal as it is sometimes called, follows
the same course as the intercostals as far as the head of the twelfth rib. It then
passes in company with the twelfth dorsal nerve along the lower border of the
twelfth rib, lying in front of the quadratus lumborum muscle, behind the fascia
transversalis. Crossing in front of it is the thickened upper bridge-like margin of
FIG. 362.-SCHEME OF INTERCOSTAL ARTERY.
Longissimus dorsi
Internal division of muscular branch
Semispinalis dorsi and multifidus spinæ
External division of muscular branch
Ilio-costalis
Posterior spinal
arteries
Retroneural
branch
Medullary branch
Preneural branch
SPINAL CORD
Anterior spinal-
artery
THORACIC
Intercostal artery-
VERTEBRA
Vena azygos.
minor
Vena azygos.
major
THORACIC DUCT
AORTA
CESOPHAGUS
Anterior intercostal,
Internal mammary artery-
Anterior perforating
branch of internal
mammary artery
STERNUM
RIB
RIB
Spinal branch
Dorsal branch
SYMPATHETIC
-Lower branch of
aortic intercostal
Upper branch of
aortic intercostal
Lateral cutaneous
branch
Lower branch of
anterior intercostal
Mammary
glandular branch
Upper branch of
anterior intercostal
this fascia, which stretches across the quadratus and gives origin to some of the
fibres of the diaphragm, and is known as the ligamentum arcuatum externum. The
subcostal artery anastomoses with the lumbar arteries and external circumflex iliac
artery. At the outer edge of the quadratus lumborum it passes between the
abdominal muscles, and is distributed in a manner similar to that of the lumbar
arteries.
(3) The diaphragmatic branches are small twigs coming off from the thoracic
aorta immediately above the diaphragm. They are distributed to the vertebral
portion of the diaphragm on its upper surface.
(4) The aberrans artery is a small twig which, arising from the thoracic aorta
near the right bronchial artery, passes upwards and to the right behind the

584
THE ARTERIES
cesophagus and trachea, and is occasionally found to anastomose on the oesophagus
with the arteria aberrans of the superior intercostal artery. It is regarded as the
remains of the right aortic dorsal stem (fig. 345).
THE ABDOMINAL AORTA
The abdominal aorta (fig. 363), the continuation of the descending or thoracic
aorta, begins at the aortic opening in the diaphragm opposite the lower border of the
FIG. 363.-THE ABDOMINAL AORTA AND ITS BRANCHES, WITH THE INFERIOR
VENA CAVA AND ITS TRIBUTARIES.
LEFT LOBE OF LIVER
Cystic artery
HEPATIC DUCT
CYSTIC DUCT
COMMON DUCT
Portal vein.
Gastro-duodenal br.
Superior pyloric
Hepatic artery
Right suprarenal vein
Inferior suprarenal
artery
Renal artery
Renal vein
Inferior vena cava
KIDNEY
Right spermatic vein
Right spermatic
artery
Quadratus lumborum
muscle
Lumbar artery and
vein
Ureteric branch of
spermatic artery
CESOPHAGUS
Left phrenic artery
Right phrenic artery
Superior suprarenal
-Gastric artery
Inferior suprarenal
Splenic artery
Left phrenic vein
Left suprarenal vein
Superior mesenteric
artery
KIDNEY
Ureteric branch
of renal
Left spermatic vein
URETER
Left spermatic artery
Inferior mesenteric
artery
Ureteric branch of
spermatic
Middle sacral vessels
Ureteric branch of
common iliac
Common iliac artery
External iliac artery
Internal iliac artery
twelfth thoracic vertebra, and ends opposite the lower border of the body of the fourth
lumbar vertebra by dividing into the right and left common iliac arteries. It is at
first centrally placed between the pillars of the diaphragm, but as it descends in
front of the lumbar vertebræ it leaves the middle line, and, at its bifurcation, lies a
little to the left side of the spine. The spot at which the aorta bifurcates is, for
all practical purposes, roughly indicated on the surface of the abdomen by a point
about half an inch below and a little to the left of the umbilicus. But the level of
its bifurcation may be more accurately determined by a line drawn across the front

ABDOMINAL AORTA
585
of the abdomen from the highest point of one iliac crest to the highest point of the
other.
The vena cava inferior, which accompanies the abdominal aorta, lies to its right
side. Below, the vein is in contact with the artery and on a somewhat posterior
plane; but above, it is separated from the aorta by the right crus of the diaphragm,
and in consequence of the caval opening in the diaphragm being placed further
forward than the opening for the aorta, is on an anterior plane.
Relations. In front (fig. 364), the aorta is successively crossed from above
downwards by the right lobe of the liver, the solar plexus, the lesser omentum, the ter-
mination of the oesophagus in the stomach, the ascending layer of the transverse
meso-colon, the splenic vein or commencement of the vena porta, the pancreas, the left
renal vein, the third portion of the duodenum, the mesentery, the aortic plexus of the
sympathetic nerve, the spermatic or ovarian arteries, the inferior mesenteric artery,
the median lumbar lymphatic glands and lymphatic vessels, and the small intestines.
Of these structures the solar plexus, the aortic plexus, the splenic vein or the
commencement of the vena porta, the pancreas, the left renal vein, the duodenum,
the lymphatics, the spermatic or ovarian arteries, and the peritoneal reflexions are
in contact with the aorta.
Behind, the aorta lies upon the bodies of the lumbar vertebræ and intervening
intervertebral cartilages, the anterior common ligament, the origin of the left crus
of the diaphragm, and the left lumbar veins.
On the right side from above downwards are the right crus of the diaphragm,
the great splanchnic nerve, the Spigelian lobe of the liver, the receptaculum chyli
and beginning of the thoracic duct (the two latter structures are on a posterior
plane), the right semilunar ganglion, and the vena cava inferior.
On the left side are the left crus of the diaphragm, the left splanchnic nerve,
and the left semilunar ganglion. The tail of the pancreas is also in contact with
the aorta on the left side, as are, too, the small intestines, but separated from it by
peritoneum.

Variations in the Abdominal Aorta
Variations in the abdominal aorta, except as regards its place of division and some
irregularity in the origin and number of its branches, are not common. According to
Quain, in ten out of every thirteen subjects examined, the bifurcation took place within
half an inch above or below the level of the highest part of the crest of the ilium. The
commonest situation for its bifurcation with reference to the vertebræ is perhaps opposite
the lower border of the body of the fourth lumbar, but it may divide opposite the disc
between the fourth and fifth lumbar, or rarely opposite the fifth lumbar. A higher division.
than at the usual spot is less common. The artery, however, has been found in exceptional
instances dividing as high as the origin of the renal arteries, or even as high as the second
lumbar vertebra.
The following rare variations have been met with:-(A) The aorta passing through
the œsophageal opening in the diaphragm. (B) The aorta lying on the right side of the
vena cava; the vein then passes over the upper part of the aorta to gain the caval opening.
(C) The aorta with a vena cava on each side, the left vein passing across the upper part
of the artery to open into the right vein just below the caval opening. (D) The aorta
giving off a pulmonary branch close to the origin of the coeliac axis, the abnormal vessel
then passing through the oesophageal opening, and supplying a branch to the lower lobe of
each lung.
The variations in the branches of the aorta are described under each branch.
BRANCHES OF THE ABDOMINAL AORTA
The branches of the abdominal aorta are given off in the following order from
above downwards (fig. 363):-
(1) Right and left phrenic; (2) coeliac axis; (3) right and left suprarenal or
capsular; (4) right and left first lumbar; (5) superior mesenteric; (6) right
and left renal; (7) right and left spermatic; (8) right and left second lumbar;

586
THE ARTERIES
(9) inferior mesenteric; (10) right and left third lumbar; (11) right and left fourth
lumbar; (12) right and left common iliac; (13) middle sacral.
The above branches may be divided into the parietal, the visceral, and the
terminal.
The parietal branches are distributed to the abdominal walls. They are the
right and left phrenics, and the four right and left lumbars.
The visceral branches supply the viscera. Three of these are given off
singly from the front of the aorta, namely, the coeliac axis, the superior mesenteric
and the inferior mesenteric; and three are given off in pairs, namely, the two
suprarenals, the two renals, and the two spermatics.
The terminal branches are the middle sacral and the right and left common
iliac arteries.
FIG. 364.-SCHEME OF THE ABDOMINAL AORTA.
DIAPHRAGM
LESSER OMENTUM
Splenic vein
PANCREAS
Left renal vein
Superior mesenteric.
artery
TRANSVERSE MESO-
COLON
THIRD PART OF
DUODENUM
TRANSVERSE COLON
MESENTERY
SMALL INTESTINES
GREAT OMENTUM
Inferior mesenteric-
artery
STOMACH
A
IL
THORACIC DUCT
12
Coeliac axis
1
First lumbar vein
RECEPTACULUM CHYLI
Second lumbar vein
GU
2
Third lumbar vein
3
4
Fourth lumbar vein
A. THE PARIETAL BRANCHES OF THE ABDOMINAL AORTA
1. THE PHRENIC ARTERIES
The right and left phrenic arteries-sometimes called the inferior phrenic to
distinguish them from the diaphragmatic branches of the internal mammary and
thoracic aorta-usually arise from the aorta as it passes between the crura of the
diaphragm either as a common trunk or as separate vessels. At times they come
off as a common trunk from the coeliac axis; or either the right or left vessel may
come from this artery, or from other of the upper branches of the abdominal aorta.
The right phrenic passes (fig. 363) over the right crus of the diaphragm behind
the vena cava, and then upwards and to the right between the central and right
leaflets of the central tendon of the muscle, where it divides into an anterior and

PHRENIC AND LUMBAR
587
posterior branch. The former courses forwards and inwards, and anastomoses with
the anterior branch of the left phrenic, with the musculo-phrenic branches of the
internal mammary, and with the superior phrenic arteries; the latter passes out-
wards and backwards towards the ribs, and anastomoses with the intercostal arteries.
Besides the two terminal branches and branches for the supply of the diaphragm
itself, the right phrenic gives off the following:-(1) Right superior suprarenal,
to the right suprarenal capsule; (2) caval, to the vena cava; (3) hepatic, to the
liver; and (4) pericardiac, to the pericardium.
The
The left phrenic crosses the left crus of the diaphragm behind the oesophagus,
and then runs between the left and central leaflets of the tendon, dividing like the
right into an anterior and a posterior branch. The former runs forwards and
inwards, and anastomoses with the anterior branch of the right phrenic, the left
musculo-phrenic from the internal mammary, and the superior phrenic artery.
latter courses outwards and backwards towards the ribs, and anastomoses with
the intercostal arteries. In addition to the terminal branches, and branches to
the diaphragm itself, the left phrenic gives off:--(1) Esophageal branches to the
œsophagus, where they anastomose with the other œsophageal branches; (2) left
superior suprarenal, to the left suprarenal body; (3) splenic, to the spleen; and
(4) pericardiac, which perforate the diaphragm and anastomose with the other
pericardiac arteries.
The variations in the origin of the phrenic arteries are very numerous. The chief
have been alluded to in the general description of the vessels.

2. THE LUMBAR ARTERIES
The lumbar arteries (figs. 360, 363), usually eight in number, four on each side,
come off in pairs from the posterior aspect of the abdominal aorta, opposite the
bodies of the four upper lumbar vertebræ. A fifth pair of lumbar arteries, gener-
ally of small size, are frequently given off from the middle sacral opposite the fifth
lumbar vertebra. The lumbar arteries, which are rather longer on the right than
on the left side, in consequence of the aorta lying a little to the left of the median
line, wind more or less transversely outwards round the bodies of the vertebræ to
the interval between the transverse processes, where they give off a dorsal branch,
and then, coursing forwards between the abdominal muscles, terminate by anasto-
mosing with the other arteries of the abdominal wall. As they wind round the
bodies of the vertebræ they pass beneath the chain of the sympathetic nerve, and
the two upper beneath the right crus of the diaphragm on the right side, and the
left crus on the left side. The right arteries also pass beneath the vena cava
inferior, and the two upper on that side beneath the receptaculum chyli. The
arteries on both sides then dip beneath the tendinous arch thrown across the sides
of the bodies of the vertebræ by the psoas, and continue beneath this muscle until
they arrive at the interval between the transverse processes of the vertebra and the
inner edge of the quadratus lumborum. Whilst under cover of the psoas they are
accompanied by two slender filaments of the sympathetic nerve and by the lumbar
veins. A little anterior to the transverse processes they are crossed by branches of
the lumbar plexus, and here usually cross in front of the ascending lumbar vein.
They now pass behind the quadratus lumborum, with the exception usually of the
first, and sometimes of the last, which may pass in front of the muscle. At the
outer edge of the quadratus they run between the transversalis and the internal
oblique, and then, perforating the internal oblique, between the internal and external
oblique. Finally, much diminished in size, they enter the rectus, and give off
one or more anterior cutaneous branches, which accompany the last dorsal and the


588
THE ARTERIES
ilio-hypogastric nerves to the skin. They anastomose with the lower intercostals,
ilio-lumbar, deep circumflex iliac, and deep epigastric arteries.
The lumbar arteries give off the following branches :-
(a) Vertebral branches which supply the bodies of the vertebræ and their
connecting ligaments.
(b) Muscular branches to the psoas, quadratus lumborum, and oblique muscles
of the abdomen.
(c) The dorsal branch. This is of large size, and passes backwards in company
with the dorsal nerve between the transverse processes above and below, the inter-
transversalis internally, and the quadratus lumborum externally, to the muscles of
the back. On reaching the interval between the longissimus dorsi and multifidus
spinæ, it divides into an external and internal branch. The former ends in the
multifidus, the latter and larger supplies the erector spinæ, and gives branches which
accompany the termination of the dorsal nerves to the skin. Just before the artery
passes between the transverse processes it gives off a spinal branch, which accom-
panies the lumbar nerve through the intervertebral foramen into the spinal canal.
Here the spinal branch divides into three twigs, one of which passes through the
sheath of the dura mater to the termination of the spinal cord and cauda equina;
the other two are distributed to the walls of the spinal canal after the way described
in the case of the intercostals.
(d) Renal branches of small size pass forwards in front of the quadratus
lumborum to the capsule of the kidney. They anastomose with the renal artery.
A communication is thus established between the renal arteries and the arteries
supplying the lumbar region.
The fifth pair of lumbar arteries, when present, usually come off from the middle
sacral artery. Each courses outwards, beneath the common iliac artery and vein;
and, after giving off a dorsal branch, ramifies over the lateral mass of the sacrum,
and ends in the iliacus muscle by anastomosing with the circumflex iliac artery.
The dorsal branch passes to the back between the last lumbar vertebra and the
sacrum and ramifies in the gluteus maximus, anastomosing with the lumbar arteries
above, and with the gluteal artery below.
The variations in the lumbar arteries are not of great importance. (A) One or more
pairs may arise as a common stem from the back of the aorta. (B) The first lumbar may
be joined at its origin with the subcostal artery; or the third and fourth lumbar, or
less often the second and third lumbar, may arise from the aorta as a common stem.
(C) The fifth pair may sometimes be absent. (D) The first lumbar may give off the
phrenic or the suprarenal. (E) One of the lumbar arteries may give off the spermatic.
(F) The fourth lumbar on either side may give off the middle sacral, or both arteries may
arise as a common stem with the middle sacral.

B. THE VISCERAL BRANCHES OF THE ABDOMINAL AORTA
THE CELIAC ARTERY
The cœliac artery-or coeliac axis as it is commonly called, because it breaks up
simultaneously into three branches which radiate from it like the spokes of a wheel
from the axle-is a short thick trunk given off from the front of the aorta between
the crura of the diaphragm a little below the aortic opening. It passes horizontally
forwards above the upper margin of the pancreas for about half an inch, and then
breaks up into its three branches for the supply of the stomach, duodenum, spleen,
pancreas, liver, and gall-bladder (fig. 365).
Relations. In front is the lesser omentum; behind, the aorta; above, the right
lobe of the liver; below, the pancreas; to the right, the right semilunar ganglion


CELIAC
589
and lobulus Spigelii of the liver; to the left, the left semilunar ganglion and the
cardiac end of the stomach. It is closely surrounded by the dense solar plexus of
sympathetic nerves.
Variations. (A) The coeliac axis may be absent; the branches usually arising
from it then coming off separately from the aorta. (B) It may be shorter or longer than
usual. Under the latter circumstance the branches are commonly given off separately from
the trunk of the vessel instead of radiating from one spot. (C) It may give off two branches
only these are usually the splenic and hepatic, more rarely the gastric and the splenic.
(D) It may give off more than three branches, the additional branch being one of the
phrenics; a trunk common to the two phrenics; a gastro-duodenal; a second gastric or
splenic artery, or the superior mesenteric; the median colic or the pancreatica magna.
(E) One or other of the branches normal to the coeliac axis may be absent, or replaced by
FIG. 365. THE CELIAC ARTERY AND ITS BRANCHES.
RIGHT CRUS OF DIAPHRAGM
Cystic artery
Right phrenic artery
CYSTIC DUCT
Splenic artery
COMMON BILE DUCT-
Pyloric artery
Superior pancreatico-
duodenal artery
HEAD OF PANCREAS-
Inferior pancreatico--
duodenal artery
Right gastro-epiploic-
artery
LIVER
Abdominal aorta
IVER
PANCREAS
S&TOM
LEFT CRUS OF DIAPHRAGM
CESOPHAGEAL BRANCH
CH
Coeliac axis
Gastric
Vasa
artery
brevia
SPLEEN
GREAT
HOME N
Left gastro-epiploic artery
a stem common to the phrenics, or by the right suprarenal and the right gastro-epiploic,
or more rarely by some other branch.
Branches of the coeliac artery. The coeliac axis gives off the gastric, hepatic,
and splenic arteries.
1. THE GASTRIC ARTERY
The gastric or coronary artery (fig. 365), the smallest of the three branches into
which the coeliac axis divides, courses at first upwards and to the left towards the
cardiac end of the stomach, where it turns sharply round, and then, coasting along
the lesser curvature of the stomach, descends from left to right towards the pylorus.
It anastomoses with the superior pyloric branch of the hepatic artery, which has
proceeded from the opposite direction, the two branches thus forming a continuous
arterial arch corresponding to the lesser curvature of the stomach. The artery at
first lies behind the posterior layer of the lesser omental sac of peritoneum (fig. 364),
but on reaching the cardiac end of the stomach it passes through the so-called
590
THE ARTERIES
pancreatico-gastric fold of peritoneum into the lesser omentum, between which it
then runs to its terminal anastomosis with the pyloric. It is surrounded by the
coronary plexus of sympathetic nerves.
The branches of the gastric artery are:-(1) The oesophageal; (2) the cardiac;
(3) the gastric; and (4) the hepatic.
(1) The œsophageal branches, given off where the artery makes its bend on
to the stomach, ascend on the oesophagus, and, passing through the oesophageal
opening of the diaphragm, anastomose with the thoracic œsophageal branches
and the branches from the left phrenic.
(2) The cardiac branches, two or more in number, are given off for the supply
of the cardiac end of the stomach, around which they form an anastomotic circle.
(3) The gastric branches come off from the artery as it lies between the layers
of the lesser omentum, and are distributed to the front and back of the stomach
(the lesser anterior and posterior gastric branches), over which they ramify,
anastomosing with branches ascending from the right and left gastro-epiploic on
the greater curvature. One of these branches of larger size ramifies over the front
of the great cul-de-sac, the greater anterior gastric (Macalister), and anastomoses
with the vasa brevia and left gastro-epiploic from the splenic.
(4) The hepatic branch is a constant small twig passing to the left lobe of the
liver, where it anastomoses with the left hepatic artery.
Chief variations. (A) The gastric may arise directly from the aorta, and may then
give off one of the phrenics, or both, or a trunk common to the two. (B) There may be
two gastric arteries instead of one. (C) The gastric may give off the left branch of the
hepatic artery. This appears to be due to the enlargement of the constantly present small
hepatic branch, and the obliteration of part of the normal left branch of the hepatic artery.
2. THE HEPATIC ARTERY
The hepatic artery, the largest branch of the cœliac axis in the foetus, but inter-
mediate in the adult between the gastric and the splenic, comes off on the right
side of the cœliac axis, and, winding upwards and to the right to the transverse or
portal fissure of the liver, there breaks up into two chief branches for the supply of
the right and left lobe of that organ. It at first courses forwards and to the right
along the upper border of the head of the pancreas, behind the posterior layer of the
lesser omental sac of peritoneum, to the upper margin of the duodenum, where, at
the base of the so-called right pancreatico-gastric fold, it passes between the two
layers of the lesser omentum, and thus ascends along with the hepatic duct which
lies to its right, and with the portal vein which lies behind it, to the transverse or
portal fissure of the liver. As it lies with the hepatic duct and portal vein between
the layers of the lesser omentum, it is in front of the so-called foramen of Winslow.
The branches of the hepatic artery are:-(1) The pancreatic; (2) the supe-
rior pyloric; (3) the gastro-duodenal; (4) the right terminal; and (5) the left
terminal.
(1) The pancreatic, or lesser pancreatic branches as they are often called,
come off from the hepatic as it runs along the upper margin of the pancreas, and
supply that organ.
(2) The superior pyloric comes off from the hepatic just as the latter vessel
enters the lesser omentum, and, descending between the two layers of that fold of
peritoneum to the pylorus, there turns leftwards, and, ascending from right to left,
anastomoses along the lesser curvature of the stomach, as already mentioned, with the
gastric artery, which descends from the opposite direction.
(3) The gastro-duodenal arises from the hepatic a little beyond the pyloric.
It descends behind the ascending portion of the duodenum to the lower border
of the pylorus, where it divides into the right gastro-epiploic and the superior
HEPATIC-SPLENIC
591
pancreatico-duodenal. It varies from half an inch to an inch in length. In
addition to the above branches, it may give off the inferior pyloric artery.
(a) The right gastro-epiploic, entering the anterior fold of the great omentum,
coasts from right to left along the greater curvature of the stomach, and anasto-
moses with the left gastro-epiploic branch of the splenic, which descends from left
to right also along the greater curvature to meet it. From this anastomotic arch
are given off:-(i) Ascending or gastric branches, which supply the anterior and
posterior surfaces of the stomach, and anastomose with the descending gastric
branches of the arteries along the lesser curvature. (ii) Epiploic or omental
branches-long slender vessels, which descend between the two anterior layers of
the great omentum, and then, looping upwards, anastomose with similar slender
branches given off from the middle and left colic, and passing down in like manner
between the two posterior layers of the great omentum.
(b) The superior pancreatico-duodenal-the smaller division of the gastro-
duodenal arises from that vessel as it passes behind the first portion of the
duodenum, and courses downwards behind the peritoneum, in the anterior groove
between the second portion of the duodenum and the pancreas, to anastomose with
the inferior pancreatico-duodenal, a branch of the superior mesenteric, which runs
upwards between the contiguous borders of the pancreas and duodenum. Both
the inferior and superior pancreatico-duodenal give off branches to the duodenum
and the pancreas.
(c) The inferior pyloric arises either from the gastro-duodenal or from the
right gastro-epiploic; it supplies the pyloric end of the stomach, and anastomoses
with the other arteries in that situation.
(4) The right terminal branch of the hepatic artery is given off at the portal
fissure of the liver, and runs to the right towards the end of that fissure, either
behind the hepatic and cystic ducts, or between these structures. At the right end
of the portal fissure it divides into two or more branches, which again subdivide as
they enter the liver substance for the supply of the right lobe. As it crosses the
cystic duct it gives off the cystic artery.
(a) The cystic artery courses forwards and downwards through the angle
formed by the union of the hepatic and cystic ducts, and just before it reaches the
gall-bladder divides into a superficial and deep branch. The former breaks up
into a number of small vessels, which ramify over the free surface of the gall-
bladder beneath the peritoneal covering, and furnish branches to the muscular
and mucous coats. The deep branch ramifies between the gall-bladder and the
liver-substance, supplying each, and anastomosing with the superficial branch.
(5) The left terminal branch, the smaller division of the hepatic artery, runs
inwards towards the left end of the portal fissure, and, after giving off a distinct
branch to the Spigelian lobe, enters the left lobe of the liver.
Chief variations. (A) The hepatic artery may arise directly from the aorta, or from the
gastric, the superior mesenteric, or the right renal artery. (B) Together with a normal
artery there may be an accessory hepatic from one or other of the above named or neigh-
bouring branches. (C) The hepatic artery may be altogether wanting, and its place supplied
by one or more accessory arteries derived from one or other of the above-named sources.
This variation is explained by Hyrtl on the supposition that there has been obliteration
of the normal hepatic, with enlargement of one or more of the minute branches which
normally proceed from the aorta and the above-named branches to the capsule of the liver.


3. THE SPLENIC ARTERY
The splenic artery-the largest branch of the coeliac axis-arises from the
left side of the termination of that vessel below the gastric, and passes along the
upper border of the pancreas in a tortuous manner to the spleen. It at first
lies behind the ascending layer of the transverse meso-colon, but on nearing the
592
THE ARTERIES
spleen enters the phreno-splenic ligament, and there breaks up into numerous
branches, which enter the hilum and supply the organ. In this course it crosses
in front of the left crus of the diaphragm and the upper end of the left kidney.
The branches of the splenic artery are:-(1) The smaller pancreatic; (2) the
larger pancreatic; (3) the left gastro-epiploica; (4) the vasa brevia; and (5) the
terminal.
(1) The smaller pancreatic branches come off from the splenic at varying
intervals, as that vessel courses along the upper margin of the pancreas. They
enter and supply the organ.
(2) The larger pancreatic branch usually arises from the splenic about the
junction of its middle with its left third. Entering the pancreas obliquely, it runs
from left to right, commonly above, and a little behind, the pancreatic duct, which
it supplies together with the substance of the organ.
(3) The left gastro-epiploic arises from the splenic behind the great cul-de-
sac of the stomach, and, passing between the anterior layers of the great omentum,
descends along the greater curvature of the stomach from left to right, and anasto-
moses with the right gastro-epiploic. Like that vessel, it gives off ascending or
gastric branches to the anterior and posterior surfaces of the stomach respectively,
and long slender descending epiploic or omental branches to the great omentum
which anastomose with like branches from the right and left colic arteries.
(4) The vasa brevia come off from the splenic just before it divides into its
terminal branches, oftentimes from some of these terminal branches themselves.
Passing from between the folds of the phreno-splenic ligament into those of the
gastro-splenic, they thus reach the greater cul-de-sac of the stomach, where,
ramifying over both its anterior and posterior surfaces, they anastomose with the
gastric and left gastro-epiploica arteries.
(5) The terminal branches, five to eight or more in number, are given off from
the splenic as it lies in the phreno-splenic ligament, and, entering the spleen at the
hilum, are distributed in the way mentioned in the description of that organ.
The variations of the splenic artery are neither numerous nor important. (A) It may
divide into two branches which reunite, the splenic vein running through the loop thus
formed. (B) It may sometimes give off branches normally derived from other vessels,
such as the gastric, the middle colic, and the left hepatic. (C) The variations in its origin
are mentioned under VARIATIONS OF THE CELIAC AXIS (page 589).
THE SUPERIOR MESENTERIC ARTERY
The superior mesenteric artery is given off from the front of the aorta a little
below the cœliac axis, which it nearly equals in size; sometimes as a common trunk
with the axis. Lying at first behind the pancreas and splenic vein, it soon passes
forwards between the lower border of that gland and the upper border of the third
portion of the duodenum, and, crossing in front of the duodenum, enters the
mesentery, in which it runs from left to right, in the form of a curve with its con-
vexity to the left, to the cæcum, where it anastomoses with its ileo-colic branch.
Its vein lies to its right side. It is surrounded by the mesenteric plexus of nerves.
The accessory portion of the head of the pancreas dips in behind the vessel.
From the concave side of the artery branches are given off to the duodenum
and the colon, viz. :-
(1) The inferior pancreatico-duodenal; (2) the middle colic; (3) the right colic;
and (4) the ileo-colic.
From the convex side branches are given off to the small intestines, viz. :-
(5) The vasa intestini tenuis.
It will thus be seen that the superior mesenteric artery supplies, with the excep-

SUPERIOR MESENTERIC
593
tion of the upper third of the duodenum, the whole of the small intestine and
half the large.
(1) The inferior pancreatico-duodenal, arising from the superior mesenteric
as that vessel emerges from the contiguous margins of the pancreas and transverse
duodenum, and, crossing behind the superior mesenteric vein, courses upwards and
to the right between the head of the pancreas and the duodenum, beneath the
ascending layer of the transverse meso-colon, to anastomose with the superior
pancreatico-duodenal, which is given off from the gastro-duodenal, and descends
in a like situation beneath the ascending layer of the transverse meso-colon.
FIG. 366.-THE SUPERIOR MESENTERIC ARTERY AND VEIN.
(The colon is turned up, and the small intestines are drawn over to the left side.)
TRANSVERSE
COLON
Middle colic
artery
Inferior
pancreatico-
duodenal
artery
Right colic
artery
Ileo-colic
artery
CÆCUM
ASCENDING
VERMIFORM
APPENDIX
PANCREAS
UM
ENDING
COLON
Left colic artery
Superior mesen-
teric artery
and vein
JEJUNUM
Vasa
intestini tenuis
-SMALL
INTESTINES
(2) The middle colic, arising from the concavity of the superior mesenteric a
little below the pancreas, enters the transverse meso-colon, and divides into two
branches-one of which passes to the left and anastomoses with the ascending
branch of the left colic; the other, winding downwards and to the right,
anastomoses with the ascending branch of the right colic.
(3) The right colic-sometimes given off as a common trunk either with the
former branch or with the ileo-colic--passes to the right behind the peritoneum to
the back of the ascending colon, where it divides into an ascending branch, which
anastomoses with the descending branch of the middle colic, and a descending branch
which anastomoses with the ascending or colic branch of the ileo-colic.
QQ

594
THE ARTERIES
(4) The ileo-colic descends behind the peritoneum towards the cæcum, where
it divides into a colic branch which tracks upwards beneath the peritoneum to
anastomose with the descending branch of the right colic; and into an ileac
branch which passes between the layers of the mesentery and anastomoses with
the termination of the superior mesenteric artery.
From the anastomotic loops formed between the termination of the superior
mesenteric, the ileo-colic, the right colic, and the middle colic arteries, secondary loops
are derived whence branches pass to the termination of the ileum, the cæcum, the
vermiform appendix, the ascending colon, and half the transverse colon. These
branches on reaching the intestine divide into two, one of which passes in front,
and the other behind the intestine, and, after encircling it, anastomose with each
other and with the neighbouring circlets above and below.
(5) The intestinal branches, or vasa intestini tenuis, arise from the convex side
of the superior mesenteric, and, varying from twelve to sixteen in number, radiate
in the mesentery, where each divides into two branches, which inosculate with
similar branches given off from the branch above and below. From the primary
loops thus formed, secondary loops are derived in like manner, and from these
tertiary, and at times quaternary, or even quinary loops. From the ultimate loops
terminal branches pass on to the intestine through the triangular interval left at
the spot where the mesentery is reflected on to the muscular coat of the gut. On
reaching the wall of the gut these terminal vessels bifurcate, the two branches
encircling the intestine, and thus forming with those above and below a series of
vascular rings surrounding the small intestine throughout its whole length. These
branches of the superior mesenteric in their course to the intestine also supply the
mesentery and the mesenteric glands.
The variations in the superior mesenteric artery are numerous. (A) It may be double. (B)
It may give off accessory branches to the liver, stomach, pancreas, spleen, and gall-bladder.
(C) It may give off branches normally derived from other sources, namely, the hepatic or
its right or left branch, the cystic, the gastro-duodenal or its right gastro-epiploic branch,
the gastric or the pancreatica magna. (D) It may give off the left colic and superior
hæmorrhoidal, thus taking the place in whole or in part of the inferior mesenteric. (E) Its
colic and intestinal branches may vary considerably in their origin and course, and in the
number of primary and secondary loops that they form. (F) A rare abnormality described
by Hyrtl is the persistence of an omphalo-mesenteric artery running to the neighbourhood
of the umbilicus and giving off a branch to the urachus, or a branch to the liver through
the falciform ligament, or a branch to the rectus anastomosing with the epigastric.
THE RENAL ARTERIES
The renal arteries come off one on each side of the abdominal aorta, a little
below the superior mesenteric and first lumbar arteries, on a level with the
first lumbar vertebra. They pass transversely outwards across the crura of the
diaphragm to the kidneys, the right being on a slightly lower plane and somewhat
longer than the left, and passing behind the inferior vena cava. In front of each
is the corresponding renal vein. Behind each at the hilum of the kidney is the
commencement of the ureter. Before entering the kidney they break up into
three or four terminal branches. The distribution of the arteries in the kidney is
described under the anatomy of that organ.
Each renal artery gives off the following branches :-
(a) The inferior suprarenal, which ascends to the suprarenal body.
(b) The capsular or perirenal branches to the capsule of the kidney and peri-
renal fat.
(c) The uretal branch to the upper end of the ureter.
Variations in the renal arteries are common. (A) The right and left renal may arise
from the aorta by a common stem. (B) They may arise from the aorta lower than usual;
RENAL-SUPRARENAL-SPERMATIC
595

the kidneys then being also below their usual situation. (C) There may be several renal
arteries on each side, or the renal artery may divide close to its origin into several branches.
(D) The renal artery on one or both sides may arise from the bifurcation of the aorta, from
the common iliac, the internal iliac, the inferior mesenteric, or the middle sacral artery.
(E) The right artery may cross in front of, instead of behind, the vena cava. (F) The branches
of the renal artery may perforate the substance of the kidney instead of entering at the
hilum. (G) The renal artery may give origin to branches normally derived from other
vessels, as the phrenic, the hepatic or its right branch from the right renal, the middle
suprarenal, some of the colic arteries, the spermatic, one or more of the lumbar arteries, or
the greater pancreatic artery. (H) Accessory renal arteries, varying in size and generally
derived from the aorta, are common. They may enter the kidney at almost any part of the
organ.
THE SUPRARENAL ARTERIES
The suprarenal arteries are derived from three sources, and are named as
follows:-(1) Superior suprarenal; (2) middle suprarenal; and (3) inferior supra-
renal.
(1) The superior suprarenals, one on each side, are usually derived from the
phrenics, and descend to the suprarenal bodies.
(2) The middle suprarenals, or suprarenals proper, come off one on each side
from the aorta, just above the first lumbar artery, and pass transversely outwards
to the suprarenal bodies, across the crura of the diaphragm a little above the renal
arteries. In the foetus they equal the renals in size. In the adult they are much
smaller.
(3) The inferior suprarenals are branches of the renals. They ascend, one on
each side, to the suprarenal bodies.
The suprarenal veins, usually one on each side, terminate as a rule on the left.
side in the left renal; on the right side, in the inferior vena cava.
The distribution of the suprarenal vessels within the suprarenal capsules is
described in the anatomy of those organs.

THE SPERMATIC ARTERIES

The spermatic arteries come off from the front of the abdominal aorta. They
diverge from each other as they descend over the aorta and psoas muscle to the
deep or internal abdominal ring, where they are joined by the vas deferens, and,
passing with it through the inguinal canal and out of the external or superficial
abdominal ring, run downwards into the scrotum in a tortuous course to the testicle.
They terminate in branches to the epididymis and body of that organ. Within
the abdomen they lie beneath the peritoneum, and cross in their descent over the
ureter and distal end of the external iliac artery; the right being superficial to
the vena cava, and behind the termination of the ileum; and the left beneath
the sigmoid flexure of the colon. In the inguinal canal and in the scrotum the
spermatic veins lie in front of the artery, and the vas deferens lies behind it.
In the foetus these vessels pass transversely outwards to the testicle, which in
early foetal life lies in the loin in front of the kidney; but as the testicles descend
to the scrotum, the vessels become elongated, and are drawn with the testicle into
the scrotum.
The spermatic arteries give off the following branches :-(1) Uretal; (2) cre-
masteric; (3) epididymal; and (4) testicular.
(1) The uretal are small branches given off to the ureter as the spermatic artery
crosses it. They anastomose with the other uretal branches derived from the
renal, common iliac, and vesical arteries.
(2) The cremasteric are small branches given off to the cremaster muscle; they
anastomose with the cremasteric branch of the deep epigastric.
922


596
THE ARTERIES
(3) The epididymal are distributed to the epididymis, and anastomose with the
artery of the vas.
(4) The testicular are the terminal branches of the spermatic; they perforate
the tunica albuginea posteriorly, and are distributed to the body of the organ in
the way mentioned in the section on the TESTICLE.
Chief variations in the spermatic arteries. (A) One or both may be wanting, the testicle
being then supplied by branches from the vesical or prostatic arteries passing under the
arch of the pubis. (B) One or both may arise from the renal, more rarely from the supra-
renal. (C) One may come off higher than the other. (D) They may come off from a
common stem. (E) One or both may be double in the whole or part of their course. (F)
The right spermatic may run behind instead of in front of the inferior vena cava.
THE OVARIAN ARTERIES
The ovarian arteries are the homologues of the spermatic arteries in the
male, and correspond in their relations in the upper part of their course. They
diverge somewhat less however, and on reaching the level of the common iliac
artery turn inwards over that vessel and descend tortuously into the pelvis between
the folds of the broad ligament to the ovaries. In the broad ligament the
ovarian artery lies below the Fallopian tube, and on reaching the ovary turns
backwards and supplies that organ (fig. 370).
They give off the following branches:-(1) Uretal; (2) Fallopian; (3) uterine;
and (4) ligamentous.
(1) The uretal is distributed, as in the male, to the ureter.
(2) The Fallopian supplies the isthmus and ampulla of the Fallopian tube and
its fimbriated extremity.
(3) The uterine runs along the Fallopian tube to the superior cornu of the
uterus, which it supplies, together with the upper part of the fundus uteri, and
anastomoses with the uterine arteries from the internal iliac.
(4) The ligamentous is distributed to the round ligament, passing with that
structure through the inguinal canal, and anastomosing with the cremasteric and
superficial external pudic arteries.
Like the spermatic, the ovarian arteries in the foetus come off at right angles
to the aorta, and pass transversely outwards to the ovaries, which are formed, as
are the testicles, in the right and left loin in front of the kidneys. They elongate
as the ovaries descend into the pelvis. During pregnancy these arteries undergo
great enlargement.

THE INFERIOR MESENTERIC ARTERY

The inferior mesenteric artery, smaller than the superior, arises from the front
of the abdominal aorta about an inch and a half above the bifurcation of that
vessel. It runs obliquely downwards and to the left, across the lower part of the
abdominal aorta and then over the left psoas muscle and common iliac artery,
descends into the pelvis between the layers of the meso-rectum, and terminates
on the rectum in the superior hæmorrhoidal or superior rectal artery. It at first
lies behind the peritoneum, or in the left lumbar meso-colon when that structure
is present. It supplies the lower half of the large intestine. Its vein lies at first
close to the left side, but soon passes upwards on the psoas, away from the artery,
to end in the splenic vein (fig. 367).
The branches of the inferior mesenteric are: (1) The left colic; (2) the sig-
moid; and (3) the superior hæmorrhoidal.
(1) The left colic runs transversely outwards and to the left, beneath the
peritoneum, and divides into two branches, one of which, entering the transverse

INFERIOR MESENTERIC
597
meso-colon, ascends upwards and to the right, to anastomose with the middle colic.
The other descends, and, entering the sigmoid meso-colon, anastomoses with the
ascending branch of the sigmoid artery.
The distribution of this artery and the next to the colon is similar to that of
the colic branches of the superior mesenteric, and does not require a separate
description. (See SUPERIOR MESENTERIC ARTERY, pages 593, 594)
(2) The sigmoid artery runs downwards and to the left over the psoas
muscle, and, entering the sigmoid meso-colon, divides into two branches; the upper
anastomosing with the left colic, the lower with the superior hæmorrhoidal.
(3) The superior hæmorrhoidal is the continued trunk of the inferior mesenteric.
It descends into the pelvis, behind the rectum, between the layers of the meso-
FIG. 367. THE INFERIOR MESENTERIC ARTERY AND VEIN.
(The colon is turned up, and the small intestines are drawn to the right side.)
Middle colic
artery
Inferior pancrea-
tico-duodenal
artery
Superior
mesenteric artery
Right colic artery
Abdominal aorta
Vena cava
inferior
Right common
iliac artery
Middle sacral
artery and vein
TRANSVERSE
COLO
PANCREAS
DESCENDING COLON
Left colic artery
Inferior
mesenteric vein
Inferior mesen-
teric artery
Left colic artery
-Inferior mesen-
teric artery
-Left common
iliac vein
Sigmoid artery
SIGMOND
FLEXURE
-Superior
hæmorrhoidal
artery
rectum. On reaching the wall of the bowel it bifurcates, one branch proceeding
on either side of the gut, to within four or five inches of the anus. Here each
again divides, and the branches, piercing the muscular coat, descend between that
coat and the mucous membrane, forming with each other, and with the middle
hæmorrhoidal arteries-derived from the internal iliac-a series of small vessels,
running longitudinally to the rectum, and parallel to each other as far as the
level of the internal sphincter, where, by their anastomosis, they form a series of
loops around the lower part of the rectum.
The chief variations in the inferior mesenteric are:-(A) Its place may be supplied by
the superior mesenteric. (B) It may give branches to the liver or kidney. (C) It may
give off the middle colic. (D) It may give off a stem to both umbilical arteries. (E) The
anastomosis between the middle and left colic arteries may be wanting-the normal
condition in the ruminants and the porcupines.

598
THE ARTERIES
C. THE TERMINAL BRANCHES OF THE ABDOMINAL AORTA
THE MIDDLE SACRAL ARTERY
The middle sacral artery is, anatomically, the continuation of the aorta, and is
generally but not universally held to be the homologue of the sacral and coccygeal
aorta of some animals. The so-called coccygeal glomerulus, or Luschka's gland, in
which it terminates, is believed to contain the rudiments of the caudal aorta, or
artery of the tail. The artery is mesially placed, and extends from the bifurcation of
the aorta to the tip of the coccyx. As it passes downwards into the pelvis, it runs
behind the left common iliac vein, the hypogastric plexus of the sympathetic nerve,
and the layer of peritoneum that descends from the mesentery into the pelvis to
become the meso-rectum. It lies successively upon the intervertebral disc between
the fourth and fifth lumbar vertebræ, the fifth lumbar vertebra, the intervertebral
disc between that vertebra and the sacrum, and lower down upon the middle of
the anterior surface of the sacrum and coccyx.
Branches. The middle sacral gives off:-
(1) The fifth pair of lumbar arteries (sometimes). These are described with
the lumbar arteries.
(2) Lateral sacral branches, usually four in number. These are serially homo-
logous with the intercostal and lumbar arteries given off by the aorta. They run
more or less transversely outwards, and anastomose with the lateral sacral branches
of the internal iliac artery. They give off small spinal branches, which pass
through the sacral foramina, and supply the sacral canal and back of the sacrum.
(3) Rectal or hæmorrhoidal branches pass forwards in the layers of the meso-
rectum, to the rectum which they help to supply, and anastomose with the other
hæmorrhoidal or rectal arteries.
On the lower part of the middle sacral artery-the coccygeal part-there are
often found small pouches or varicosities, which are believed by some to represent
the rudiments of lateral coccygeal arteries, homologous to the intercostal, lumbar,
and sacral arteries, given off from the aorta in these regions.
The variations of this vessel are unimportant. (A) The most frequent perhaps is for
it to come off from the back of the aorta a little above the bifurcation; or (B) from one
or other of the common iliacs; or (C) as a common trunk with what are usually its
branches, the fifth pair of lumbar arteries. (D) It sometimes gives off an accessory
renal artery a fact of interest, in that the kidneys occupy a lower position in the abdomen in
some animals than in man.
THE COMMON ILIAC ARTERIES
The common iliac arteries must be regarded as the terminal branches of the
abdominal aorta, unless the middle sacral and the artery of the tail in the lower
animals are regarded as the continuation of the abdominal aorta. The common iliacs
arise opposite the left side of the lower border of the body of the fourth lumbar
vertebra, at the bifurcation of the abdominal aorta, and, diverging from each
other in the male at about an angle of 60°, and in the female at an angle of 68°,
terminate opposite the upper margin of the sacro-iliac synchondrosis by bifurcating
into the external iliac, which is continued along the brim of the pelvis to the
lower limb, and into the internal iliac, which passes over the brim of the pelvis
and descends into that cavity. Both arteries lie on the fifth lumbar vertebra,
are covered by the peritoneum, and are crossed by the ureter, and in the female,
in addition, by the ovarian arteries.
COMMON ILIAC
599
The relations of the arteries differ slightly on the two sides, and may be
considered separately.
THE RIGHT COMMON ILIAC ARTERY
The right common iliac measures about two inches in length (5 cm.), and is
rather longer than the left, in consequence of the aorta bifurcating a little to the
left of the median line.
Relations. In front it is covered by the peritoneum, and is crossed by the right
ureter a little before its bifurcation, by the ovarian artery in the female, by the ter-
mination of the ileum, by the terminal branches of the superior mesenteric artery,
and by branches of the sympathetic nerve descending to the hypogastric plexus.
Behind, it lies on the right common iliac vein, the end of the left common iliac
vein, and the commencement of the inferior vena cava, which separate it from the
fourth and fifth lumbar vertebræ and their intervening discs, the psoas muscle, and
the sympathetic nerve; whilst still deeper in the groove between the fifth lumbar
vertebra and the psoas are the lumbo-sacral cord, the obturator nerve, and the ilio-
lumbar artery.
To the right side are the beginning of the inferior vena cava, the end of the
right common iliac vein, and the psoas muscle.
To the left side are the right common iliac vein, the termination of the left
common iliac vein, and the hypogastric plexus.
It will be thus seen that the right common iliac artery crosses both common
iliac veins, and that its own vein, the right, is at first a little to the left side, but,
as it ascends, passes beneath it, and gets a little to the right side. Since the
bifurcation of the vena cava is a little below and to the right side of the bifurcation
of the aorta, it follows that the right common iliac artery lies on the commence-
ment of the vena cava.

THE LEFT COMMON ILIAC ARTERY
The left common iliac artery, one inch and three-quarters in length (4 cm.), is
a little shorter and thicker than the right.
Relations. In front it is covered by the peritoneum, which separates it from the
intestines, and is crossed by the ureter, the ovarian artery in the female, branches
of the sympathetic nerve descending to the hypogastric plexus, the termination of
the inferior mesenteric artery, the sigmoid flexure, and the sigmoid meso-colon.
Behind are the lower border of the body of the fourth lumbar vertebra, the disc
between the fourth and fifth lumbar vertebræ, the body of the fifth lumbar
vertebra, and the disc between it and the sacrum, and the psoas muscle, from
which it is separated by the left common iliac vein. Crossing deeply behind the
artery between the fifth lumbar vertebra and the psoas, is the obturator nerve,
the lumbo-sacral cord, and the ilio-lumbar artery.

To the left side is the
psoas muscle.
To the right side are the left common iliac vein, the hypogastric plexus, and the
middle sacral artery.
Variations in the Common Iliac Arteries
(A) The common iliac arteries may be longer or shorter than here described. They
have been found as short as half an inch, or as long as four and a half inches, but the usual
limit is something between one and a half to three inches. This variation in the length of
the vessels may depend upon the aorta bifurcating above or below the usual spot, or upon
the common iliac arteries dividing higher or lower than usual. A low bifurcation of the
aorta is somewhat more common than a high bifurcation, as is also the case with the
common iliacs. (B) The common iliacs may be absent, the external and internal iliacs
then arising together from the end of the aorta. (C) Either artery may give off a large
branch, such as the ilio-lumbar, the lateral or the middle sacral, sometimes a lumbar, or
occasionally an accessory renal artery.
600
THE ARTERIES
Collateral Circulation

The collateral circulation after obstruction or ligature of the common iliac artery is carried
on chiefly (fig. 374) by the anastomosis of the middle sacral with the lateral sacral; the internal
mammary with the epigastric; the lumbar arteries of the aorta with the ilio-lumbar and
deep circumflex iliac; the pubic branch of the epigastric with the pubic branch of the
obturator; the posterior branches of the sacral arteries with the gluteal; the superior
hæmorrhoidal from the superior mesenteric, with the hæmorrhoidal branches of the internal
iliac and pudic; the ovarian arteries from the aorta with the uterine branches of the
internal iliac; and by the anastomosis across the middle line of the pubic branch of the obtu-
rator with the like vessel of the opposite side; the lateral sacral with the opposite lateral
sacral; and the vesical, hæmorrhoidal, uterine, and vaginal branches of the internal iliac
with the corresponding branches of the opposite internal iliac.
BRANCHES OF THE COMMON ILIAC ARTERY
The branches of the common iliac arteries are:-(1) Peritoneal and sub-
peritoneal; (2) ureteric; (3) internal iliac ; and (4) external iliac.
(1) The peritoneal and subperitoneal are distributed to the peritoneum and
subperitoneal fat. They anastomose with like vessels given off from the lumbar,
phrenic, and renal arteries, forming a subperitoneal arterial anastomosis. They
are very small and unimportant.
(2) The ureteric are small insignificant twigs given off to the ureter as that
tube crosses the artery. They anastomose with the ureteric arteries given off from
the spermatic above, and with those derived from the vesical arteries below.
(3) THE INTERNAL ILIAC ARTERY
The internal iliac artery arises at the bifurcation of the common iliac opposite
the upper margin of the sacro-iliac synchondrosis. It descends into the pelvis for
about an inch and a quarter (3 cm.), and then divides, opposite the upper margin
of the great sacro-sciatic foramen, into an anterior and a posterior branch.
Relations. Behind, it rests on the termination of the external iliac vein, the
internal iliac vein, the inner margin of the psoas muscle, the lumbo-sacral cord, the
obturator nerve, and the sacrum.
In front it is covered by the peritoneum, and is crossed by the ureter.
In the adult the internal iliac is smaller than the external iliac; but in the fœtus
the internal is much larger than the external, and is, together with its anterior
branch, the vessel by which the blood is returned to the placenta. In early fœtal
life it does not descend into the pelvis, but courses above the pelvic brim by the side
of the allantois, and later by the side of the bladder and urachus, to the umbilicus,
under the name of the hypogastric artery. At the umbilicus it is joined by the
umbilical vein, and by the hypogastric artery of the opposite side. The two arteries,
now known as the umbilical, coil spirally round the vein on their way to the
placenta, forming the umbilical cord (fig. 368). After birth the hypogastric artery
ceases to be pervious beyond the superior vesical branch, and is converted into a
fibrous cord, the obliterated hypogastric artery.
Variations. (A) The internal iliac may be longer or shorter than usual. It is seldom
less than an inch in length, but has been met with as short as half an inch, and as long as
three inches. The variation in length generally depends upon the length of the common
iliac; when this bifurcates higher than usual, the internal iliac is then longer, and may
lie at first above the brim of the pelvis; but the length may also depend upon the
artery itself dividing higher or lower than usual into its branches. This division may
occur anywhere between the brim of the pelvis and the upper border of the sacro-sciatic
foramen. (B) Its branches may be given off without the artery dividing into an anterior
and posterior division, or one or more branches may arise above the division.




INTERNAL ILIAC-ILIO-LUMBAR
601
The branches of the posterior division of the internal iliac are :-(1) The
ilio-lumbar; (2) the lateral sacral; and (3) the gluteal.
The branches of the anterior division are:-(1) The hypogastric; (2) the superior,
middle, and inferior vesical; (3) the middle hæmorrhoidal; (4) the uterine; (5) the
vaginal; (6) the obturator; (7) the sciatic; and (8) the internal pudic.
FIG. 368.-SIDE VIEW OF PELVIS AND UPPER THIRD OF THIGH, WITH THE EXTERNAL
ILIAC, INTERNAL ILIAC, AND FEMORAL ARTERIES AND THEIR BRANCHES.
(From a dissection by W. J. Walsham in the Museum of St. Bartholomew's Hospital.)
The bladder is hooked over to expose back of pelvis.
Common iliac artery
SYMPATHETIC NERVE
Middle sacral artery
Common iliac vein.
URETER.
Internal iliac artery-
External iliac vein-
External iliac artery-
Posterior br. of internal iliac dividing.
into gluteal and ilio-lumbar arteries
Lateral sacral artery
SACRAL PLEXUS-
OBTURATOR NERVE-
Obturator artery.
Obliterated hypogastric
Superior vesical artery
Psoas muscle
Ilio-lumbar artery
EXTERNAL CUTANEOUS
NERVE
Iliacus muscle
GENITO-CRURAL NERVE
- ANTERIOR CRURAL NERVE
Edge of levator ani
Pudic artery
BLADDER
Middle vesical artery.
Deep epigastric artery-
Pubic br. of epigastric.
artery
Common femoral artery-
Long saphenous vein-
Pectineus muscle-
Obturator artery.
Adductor magnus.
Internal circumflex artery.
Adductor brevis
OBTURATOR NERVE (ant. branch)
Profunda arter y
Adductor longus, hooked aside.
Superficial femoral artery and vein
Deep circumflex iliac artery
Superficial circumflex iliac artery
ANTERIOR CRURAL NERVE
Gluteal artery and nerve
Tensor faciæ femoris (hooked
aside)
Gluteus medius and minimus
Sartorius muscle
MIDDLE CUTANEOUS NERVE
NERVE TO RECTUS
NERVE TO VASTUS
EXTERNUS
External circumflex artery
NERVE TO CRUREUS
Rectus, hooked aside
Profunda vein
NERVE
LONG SAPHENOUS
AND
INTERNUS
NERVE TO VASTUS
Gracilis muscle.
Lower part of sartorius,
Vastus internus muscle
BRANCHES OF THE POSTERIOR DIVISION OF THE INTERNAL ILIAC ARTERY
1. THE ILIO-LUMBAR ARTERY
The ilio-lumbar artery-a short vessel coming off from the posterior part of
the internal iliac artery-runs upwards and outwards beneath the common iliac
artery, first between the lumbo-sacral cord and obturator nerve, and then between
602
THE ARTERIES

the psoas muscle and the vertebral column. On reaching the brim of the pelvis it
divides into two branches, an iliac and a lumbar. The iliac branch passes outwards
beneath the psoas and anterior crural nerve and, perforating the iliacus, ramifies in
the iliac fossa between that muscle and the bone. It supplies a nutrient artery to
the bone, and then breaks up into several branches which radiate from the parent
trunk, upwards towards the sacro-iliac synchondrosis, outwards towards the crest
of the ilium, downwards towards the anterior superior spine, and inwards towards
the pelvic cavity. The first anastomoses with the last lumbar; the second with
the external circumflex and gluteal; the third with the deep circumflex iliac from
the external iliac; the fourth with the iliac branch of the obturator. The lumbar
branch ascends beneath the psoas, and, supplying that muscle and the quadratus
lumborum, anastomoses with the last lumbar artery. It sends a branch into the
spinal canal through the intervertebral foramen between the last lumbar vertebra
and the sacrum, which anastomoses with the other spinal arteries. The ilio-lumbar
artery is serially homologous with the lumbar arteries. Hence the similarity in
its course and distribution.
2. THE LATERAL SACRAL ARTERIES
The lateral sacral arteries, usually two in number, arise from the posterior
division of the internal iliac. The superior artery, when two are present, runs
downwards and inwards to the first anterior sacral foramen, through which it passes;
and, after supplying the spinal membranes and anastomosing with the other spinal
arteries, passes through the first posterior sacral foramen, and is distributed to the
skin over the back of the sacrum, there anastomosing with branches of the gluteal
and sciatic arteries. The inferior lateral sacral descends on the side of the sacrum,
external to the sacral chain of the sympathetic, and internal to the anterior sacral
foramina, crossing in its course the slips of origin of the pyriformis muscle and
the first anterior sacral nerve. On reaching the coccyx it anastomoses in front of
that bone with the middle sacral artery, and with the inferior lateral sacral of the
opposite side. In this course it gives off:-Posterior or spinal branches, which enter
the second, third, and fourth anterior sacral foramina, and, after supplying the
spinal membranes and anastomosing with each other, leave the spinal canal by the
corresponding posterior sacral foramina, and are distributed to the muscles and
skin over the back of the sacrum; anterior or rectal branches which run forward
to the rectum; external branches which are distributed to the pyriformis, coccygeus,
and the sacral nerves; and internal branches which pass inwards across the sacrum
to anastomose with branches of the middle sacral artery.
At times the lateral sacral arteries are exceedingly small, the spinal branches
then coming chiefly from the middle sacral. The anastomosing branches between
the lateral sacral and middle sacral are usually regarded as sacral arteries
diminished in size, and serially homologous with the lumbar and intercostal arteries.

3. THE GLUTEAL ARTERY

The gluteal artery, the largest branch of the posterior division of the internal
iliac, comes off as a short, thick trunk from the outer and back part of that vessel,
of which indeed it may be regarded as the continuation. Passing backwards
between the first sacral nerve and the lumbo-sacral cord through an osseo-tendinous
arch formed by the margin of the bone and the upper edge of the pelvic fascia, it
leaves the pelvis through the great sacro-sciatic foramen above the pyriformis muscle
in company with its vein and the superior gluteal nerve. At its exit posteriorly
from the great sciatic foramen it lies under cover of the gluteus maximus and

GLUTEAL
603
beneath the gluteal vein, and in front of the superior gluteal nerve. It here breaks
up into two chief branches, a superficial and a deep. Its emergence from the
pelvis is indicated on the surface by a point situated at the junction of the posterior
with the middle third of a line drawn from the anterior superior to the posterior
superior spine of the ilium.
Branches of the gluteal artery :-
(a) Within the pelvis, branches are distributed to the obturator internus,
the pyriformis, the levator ani, the coccygeus, and the pelvic bones.
(b) External to the pelvis, the artery divides into a superficial and deep branch.
FIG. 369. THE GLUTEAL REGION, WITH THE GLUTEAL, SCIATIC, AND PUDIC ARTERIES.
(From a dissection by W. J. Walsham in St. Bartholomew's Hospital Museum.)
The inferior gluteal branch of the sciatic artery has been drawn inwards over the tuber ischii
with the reflected origin of the gluteus maximus muscle.
Gluteus medius, turned up
INFERIOR GLUTEAL NERVE
Gluteus maximus, cut
Internal circumflex artery
Gluteus minimus
Muscular branches of sciatic artery
Deep branch of gluteal artery
SUPERIOR GLUTEAL NERVE
Obturator externus
Insertion of gluteus medius
External circumflex artery
GREAT TROCHANTER
Pyriformis perforated by peroneal
portion of sciatic nerve
Cut edge of gluteus maximus
Insertion of
gluteus maximus
First perforating artery
Quadratus femoris
Branch of internal circumflex artery
Obturator internus with the two gemelli
TUBER ISCHI
Biceps
Pudic artery and nerve
Sciatic artery
Semi-tendinosus
Semi-membranosus
LESSER SCIATIC NERVE
Arteria nervi comes ischiatici
POPLITEAL PORTION OF GREAT SCIATIC NERVE
LONG PUDENDAL NERVE
PERONEAL PORTION OF GREAT SCIATIC NERVE
(i) The superficial branch breaks up into a number of large vessels for the
supply of the upper portion of the gluteus maximus, some of them piercing the
muscle and supplying the skin over it, and anastomosing with the posterior branches
of the lateral sacral arteries; whilst one of larger size, emerging from the muscle
near the iliac crest, anastomoses with the deep circumflex iliac artery. The lower
branches to the muscle anastomose with branches of the sciatic.
604
THE ARTERIES

(ii) The deep branch subdivides into a superior and inferior branch. (a) The
superior skirts along the line of origin of the gluteus minimus, between the gluteus
medius and the bone, and, emerging in front from beneath these muscles under
cover of the tensor fasciæ femoris (fig. 368), anastomoses with the ascending branch
of the external circumflex and deep circumflex iliac arteries. (B) The inferior branch
passes forwards between the gluteus medius and minimus, accompanied by the
branch to the tensor fasciæ femoris of the inferior division of the superior gluteal
nerve towards the great trochanter, where it anastomoses with the ascending branch
of the external circumflex. It supplies branches to the contiguous muscles and to
the hip joint.
The deep branch before its division gives off the external nutrient artery of the
ilium.
BRANCHES OF THE ANTERIOR DIVISION OF THE INTERNAL
ILIAC ARTERY
1. THE HYPOGASTRIC ARTERY

The hypogastric artery, the main trunk of the internal iliac in the foetus,
is the apparent continuation of the anterior branch of the internal iliac. Passing
forwards along the side of the pelvis, it enters the lateral false ligament of the
bladder, where, after giving off one or more vesical branches, it ceases to be pervious
as it passes on to the side and upper part of the bladder. Thence it ascends, under
cover of the anterior false ligament, as a fibrous cord, to the umbilicus, where it is
joined by its fellow of the opposite side. As it lies in the lateral false ligament it
is crossed by the vas deferens.
2. THE VESICAL ARTERIES
The vesical arteries are divided into the superior, middle, and inferior.
(1) The superior vesical artery-though usually described as a branch of the
internal iliac, inasmuch as it is apparently given off from the anterior division of
that vessel is really a branch of the unobliterated portion of what, in the foetus, was
the hypogastric artery. It ramifies over the upper fundus of the bladder, anasto-
mosing with the vessel of the opposite side and with the middle and inferior vesical
below. It gives off the following branches :-(a) The deferential, or artery of
the vas deferens, arises from the superior vesical near the spot where the vas
crosses the obliterated hypogastric artery, and, having reached the vas, divides
into an ascending and descending branch. The ascending branch follows the vas
through the inguinal canal to the testicle, where it anastomoses with the sper-
matic artery. The descending branch passes downwards to the dilated portion of
the vas and vesiculæ seminales. (b) The uracheric branch passes upwards along
the urachus. (c) The ureteric branches pass to the lower end of the ureter,
which they supply, and anastomose with the other ureteric arteries. (d) The
middle vesical (sometimes).
(2) The middle vesical is a branch either of the superior vesical, or of the
unobliterated portion of the hypogastric artery. In the latter case it is given off
before the superior vesical. It is distributed to the sides and base of the bladder,
and anastomoses with the other vesical arteries.
(3) The inferior vesical arises from the anterior division of the internal iliac,
frequently in common with the middle hæmorrhoidal, and passes downwards and
inwards to the base of the bladder, where it breaks up into branches which ramify
over the lower part of the viscus. It gives off:-(a) Branches to the prostate,
which supply that organ and anastomose with the arteries of the opposite side by


VESICAL-UTERINE
605
means of descending arteries which pass through the prostatic plexus of veins, but
outside the capsule of the prostate, and with the inferior hæmorrhoidal branches of
the internal pudic. At times one of these prostatic branches is of large size, and
supplies certain of the parts normally supplied by the internal pudic. It is then
known as the accessory pudic. (b) Branches to the vesiculæ seminales; and (c)
branches (in the female) to the vagina. (See VAGINAL ARTERY.) The artery of
the vas deferens sometimes arises from the inferior vesical, instead of from the
superior vesical.
3. THE MIDDLE HÆMORRHOIDAL ARTERY
The middle hæmorrhoidal or the middle rectal artery, variable in its origin,
perhaps most commonly arises from the anterior division of the internal iliac along
with the inferior vesical. It runs inwards to the sides of the middle portion of
the rectum, dividing into branches which anastomose above with the superior
hæmorrhoidal derived from the inferior mesenteric, and below with the inferior
hæmorrhoidal derived from branches of the pudic. Its corresponding vein termi-
nates in the inferior mesenteric vein.
4. THE UTERINE ARTERY
The uterine artery arises from the anterior branch of the internal iliac close
to or in conjunction with the middle hæmorrhoidal or inferior vesical. It runs down-
wards and inwards in the pelvic connective tissue, crossing the ureter about half an
FIG. 370.-SCHEME OF THE OVARIAN AND UTERINE AND VAGINAL ARTERIES.
Cervical branch
Coronal artery'
UTER U
MAGINA
Branch
Uterine to round
Branches
to
branch ligament
isthmus
Branch
to
ampulla
FIMBRIATED
EXTREMITY OF
FALLOPIAN TUBE
VAR
ROUND
LIGAMENT
Ovarian artery
Ovarian branches
Uterine artery
Internal iliac artery
Vaginal arteries
Azygos artery of vagina
inch from the cervix uteri. It then turns upwards and ascends between the layers
of the broad ligament on the side of the uterus in a coiled and tortuous manner,
and, after giving off a number of tortuous branches which ramify in a horizontal
606
THE ARTERIES

manner over the front and back of the uterus, supplying its substance, anasto-
moses with the uterine branch of the ovarian artery. The distribution of the
vessel in the uterus will be described with that organ. The branches of the uterine
artery are:-(1) Cervical.-This branch comes off from the uterine as the latter
artery crosses the ureter to turn upwards on to the uterus. It runs directly inwards,
and divides into three or four branches which pass on to the cervix at right angles
to it; one branch anastomosing with its fellow of the opposite side in front and
behind the neck, forming the so-called coronary artery of the cervix. (2) Vaginal
azygos. A second branch descends both in front and behind in the middle line
of the cervix on to the vagina, and forms, with branches of the vaginal arteries,
the so-called azygos artery of the vagina.
—
5. THE VAGINAL ARTERIES
The vaginal arteries come off separately from the anterior division of the
internal iliac, or one or more of them may arise in common with the inferior
vesical, uterine, or middle hæmorrhoidal arteries. They are usually two or three in
number. They pass through the pelvic connective tissue to the side of the vagina,
supplying its walls, and anastomosing with the corresponding arteries of the
opposite side, with each other, and with tortuous branches from the artery of the
cervix, a branch of the uterine. With this vessel they form a more or less vertical
trunk in the median line of the vagina, both back and front. This vessel is known
as the azygos artery of the vagina. The lower vaginal arteries extend to the bulb
of the vestibule, where they communicate with the bulbal branch of the internal.
pudic. Small branches extend also on to the rectum.
6. THE OBTURATOR ARTERY
The obturator artery comes off from the anterior division of the internal iliac
at about the same spot as the hypogastric. Occasionally it arises from the posterior
division. Its runs forward and downwards a little below the brim of the pelvis,
having the obturator nerve above, and the obturator vein below. It here lies
between the peritoneum and the pelvic fascia, but pierces the fascia to gain the
obturator canal, the aperture in the upper and outer part of the obturator membrane.
In this course it is crossed by the vas deferens. On emerging from the obturator
canal, the artery divides into two branches, an external and an internal, which wind.
round the margin of the thyroid foramen beneath the obturator externus muscle.
Within the pelvis the artery gives off:-(1) An iliac or nutrient branch;
(2) a vesical branch; and (3) a pubic branch. Without the pelvis, it divides
into: (1) An external branch; and (2) an internal branch.
A. Intrapelvic branches.-(1) The iliac or nutrient branch ascends to the iliac
fossa, passing between the iliacus muscle and the bone. It supplies a nutrient
vessel to the ilium, and anastomoses with the internal branch of the iliac division
of the ilio-lumbar artery.
(2) The vesical branch or branches are small vessels which run in the lateral
false ligament of the bladder to that organ, where they anastomose with the other
vesical arteries.
(3) The pubic branch comes off from the obturator as that vessel is leaving the
pelvis by the obturator canal. It runs upwards and inwards behind the pubes,
anastomosing with its fellow of the opposite side of the body, and with the pubic
branch of the deep epigastric artery. One of the anastomosing channels between
the pubic branch of the obturator and pubic branch of the deep epigastric arteries

OBTURATOR-SCIATIC
607
is sometimes of large size, a fact of surgical interest in that the enlarged vessel may
then run round the inner side of the femoral ring (page 613).
B. Extrapelvic branches.-(1) The external branch skirts the external margin.
of the thyroid foramen, lying between the obturator externus and the obturator
membrane. At the lower margin of the foramen it divides into two branches. One
branch continues its course round the lower margin of the foramen, and anasto-
moses with the internal branch of the obturator and with the internal circumflex.
The other branch turns outwards below the acetabulum, and ends in the muscles
arising from the tuberosity of the ischium. It anastomoses with the sciatic artery.
This branch gives off a small twig which passes under the transverse ligament into
the hip joint, where it supplies the synovial membrane, the ligamentum teres, and
the fat in the fossa at the bottom of the acetabulum.
(2) The internal branch runs round the inner margin of the thyroid foramen, and
anastomoses with the inner division of the external branch and with the internal
circumflex artery. It supplies branches to the obturator and adductor muscles.

7. THE SCIATIC ARTERY

The sciatic artery-the larger of the terminal branches of the anterior division
of the internal iliac-passes over the sacral plexus and pyriformis muscle to the
lower part of the great sciatic foramen, where it leaves the pelvis with the pudic
artery, behind and external to which it lies, by passing between the pyriformis and
coccygeus muscles. On emerging from the great sciatic foramen in the gluteal region
under cover of the gluteus maximus, it descends to the inner side of the great sciatic
nerve, lying midway between the tuberosity of the ischium and the great trochanter
on the gemellus superior, obturator internus, gemellus inferior, quadratus femoris,
and upper part of the adductor magnus muscles. It anastomoses with the internal
circumflex artery, and superior perforating branch of the profunda. The branches
of the sciatic artery are divided into the intra- and extra-pelvic.
The intrapelvic branches are small and unimportant, and irregular in their
origin and distribution. They are given off to the levator ani, coccygeus, and
pyriformis muscles, the rectum, bladder, prostate gland, and vesiculæ seminales.
The extrapelvic branches are: (1) The coccygeal; (2) inferior gluteal; (3) mus-
cular; (4) anastomotic; (5) articular; (6) cutaneous; and (7) comes nervi ischiatici.
(1) The coccygeal is a small branch which passes inwards, and, piercing the
great sacro-sciatic ligament and the gluteus maximus, is lost in the integument
over the lower part of the sacrum and coccyx. It gives several branches to the
lower and internal part of the gluteus maximus as it passes through it.
(2) The inferior gluteal is a fairly large branch which arises from the sciatic
just below the coccygeal, and, turning upwards and inwards into the deep surface
of the gluteus maximus along with the inferior gluteal nerve, supplies that muscle,
and anastomoses with the gluteal artery.
(3) The muscular branches, variable in their number and origin, pass to the
pyriformis, obturator internus, and gemelli muscles, anastomosing with the pudic,
the internal circumflex, and the obturator arteries.
(4) The anastomotic branch crosses the external rotator muscles either over or
under the great sciatic nerve, and contributes to the formation of the so-called crucial
anastomosis by anastomosing with the first perforating below, the termination
of the internal circumflex internally, and the transverse branch of the external
circumflex externally (fig. 369).
(5) The articular branches pass beneath the external rotator muscles with the
nerve to the quadratus femoris, and send several filaments into the posterior part of
the capsule of the hip joint.
608
THE ARTERIES

(6) The cutaneous branches turn round the lower border of the gluteus
maximus, along with branches of the small sciatic nerve, and supply the integu-
ment of that region.
(7) The comes nervi ischiatici is a long slender vessel which passes down the
back of the thigh with the great sciatic nerve, to which it sends numerous branches.
It anastomoses with the internal circumflex, and with the first, second, and third
perforating arteries, and with the termination of the profunda, or fourth perfora-
ting. After ligature of the femoral in Scarpa's triangle, this artery becomes greatly
enlarged, and contributes through its anastomosis with the above-mentioned
arteries to the supply of the parts below the ligature.
8. THE INTERNAL PUDIC ARTERY
The internal pudic artery-the smaller of the two terminal branches of the
anterior division of the internal iliac artery-comes off with the sciatic, the other
terminal branch, either separately or as a common trunk, opposite the pyriformis
muscle. It descends with the sciatic over the pyriformis and sacral plexus of
nerves, lying anterior and internal to the latter artery as far as the lower border
of the great sciatic foramen, where it passes out of the pelvis between the pyriformis
and coccygeus muscles. It then winds over the outer surface of the spine of the
ischium under cover of the gluteus maximus, and re-enters the pelvis through the
lesser sciatic notch. Running forwards over the obturator internus muscle, it
passes through the base of the triangular ligament, and, continuing its course along
the ramus of the pubes, gives off between the two layers of the triangular ligament
the artery of the crus and the artery of the bulb, and is continued through the
anterior layer of the ligament as the dorsal artery of the penis.
The relations of the artery may be considered:-(1) As it lies within the pelvis ;
(2) as it crosses the spine of the ischium; (3) as it lies on the obturator internus
muscle, in the outer wall of the ischio-rectal fossa; and (4) as it lies between the two
layers of the triangular ligament.
(1) Within the pelvis the artery crosses the pyriformis muscle and sacral plexus
of nerves, lying somewhat anterior and internal to the sciatic artery, which is usually
given off from the internal iliac along with it. At the lower border of the sciatic
foramen it leaves the pelvis by passing between the pyriformis and coccygeus
muscles along with the sciatic artery, the pudic nerve, the greater and lesser sciatic
nerves, and the nerve to the obturator internus.
(2) As it crosses the spine of the ischium it has a companion vein on either side,
the pudic nerve on its inner side, and the nerve to the obturator internus on its outer
side. It is covered by the gluteus maximus muscle, and more or less by the over-
lapping edge of the great sacro-sciatic ligament. In a thin subject it can be felt
pulsating as it crosses the ischial spine. A spot taken at the junction of the inner
with the outer two-thirds of a line drawn from the top of the great trochanter with
the femur rotated inwards to the base of the coccyx, indicates externally the situation
of the artery as it crosses the ischial spine. In this situation it may, in a thin
subject, be compressed. The branches of the artery in this part of its course are:
(a) Small twigs to the gluteus maximus; (b) a small branch to the obturator internus
which accompanies the nerve to that muscle; (c) a sacral branch which pierces
the great sciatic ligament and anastomoses with the sciatic artery.
(3) In the third part of its course, as it lies on the obturator internus muscle,
in the outer wall of the ischio-rectal fossa, it is placed about an inch and a half
(3.5 cm.) above the lower margin of the tuberosity of the ischium. It is here bound
down to the muscle by a strong sheath of the obturator layer of the pelvic fascia
(Alcock's canal). In this part of its course the dorsal nerve of the penis and the



INTERNAL PUDIC
609
superficial perinæal nerve, into which the pudic nerve divides about this situation, lie
respectively above and below the artery.
The branches of the pudic artery in the third part of its course are :-(a) The
external or inferior hæmorrhoidal; and (b) the superficial perinæal.
(a) The external or inferior hæmorrhoidal branches (inferior or posterior anal)
are given off from the pudic at the posterior part of the ischio-rectal fossa, just
after it enters the outer wall of that cavity through the lesser sciatic foramen.
They perforate the sheath of obturator fascia binding the pudic artery to the
obturator internus, and course transversely through the fat of the ischio-rectal fossa,
inwards to the anus, where they supply the sphincter muscle and levator ani, and
anastomose with the superior and middle hæmorrhoidal arteries. Twigs are given
FIG. 370A.-THE ARTERIES OF THE PERINEUM.
On the right side Colles's fascia has been turned back to show the superficial vessels. On the
left side the superficial vessels have been cut away with the anterior layer of the triangular
ligament to show the deep vessels.
Superficial perineal-
vessels
Accelerator urinæ.
Crus penis
Dorsal artery of penis
Artery of crus
Colles's fascia, turned-
back
Erector penis-
Transverse perineal vessels-
Cut edge of triangular-
ligament
SUPERFICIAL
PERINEAL NERVE
Pudic vessels
Transverse perineal vessels-
and nerve
BULB
Artery of bulb
COWPER'S GLAND
Pudic artery
Great sciatic ligament
Levator ani
-External sphincter
Gluteus maximus
Gluteus maximus,
hooked back
off from them to the skin covering the anal triangle of the perinæum; other
branches supply the gluteus maximus and wind over the posterior fold of that
muscle to the integuments; whilst others again run forwards and anastomose with
the transverse and superficial perineal arteries (fig. 370A).
(b) The superficial perineal branch arises from the pudic at the front of the
ischio-rectal fossa, just before that vessel pierces the posterior layer of the triangular
ligament. It passes through the deep layer of the superficial fascia of the perinæum,
(Colles's fascia), where that structure is continued into the anterior layer of the
triangular ligament round the transverse perinæal muscle. It then crosses in front
of (occasionally behind) that muscle, and enters the perineal triangle, the space
between Colles's fascia and the anterior layer of the triangular ligament, bounded
by the erector penis externally, the accelerator urinæ internally, and the transverse
RR
610
THE ARTERIES
perinæal muscle below. On nearing the apex of this triangle it divides into long
slender branches, which are continued along the back of the scrotum, anastomosing
with the superficial external pudic branch of the common femoral. In this course
it is accompanied by the superficial perinæal nerve. It supplies the contiguous
muscles and the integuments of the scrotum. As a rule it gives off the following
branch:--
The transverse perineal artery usually arises from the before-mentioned
artery. Occasionally it is a direct branch from the pudic trunk. It courses trans-
versely inwards, on the transverse perinæal muscle, towards the central tendon
of the perinæum, supplying the muscles and integuments of the perinæum, and
anastomosing with its fellow of the opposite side.
(4) In the fourth part of its course the pudic artery lies between the two layers
of the triangular ligament, close to the ramus of the pubes, in the substance of the
compressor urethræ muscle, having the anterior layer of the triangular ligament in
front and the posterior layer behind. In this situation it gives off the artery of the
bulb and the artery of the crus penis, and then continues its course forwards
FIG. 371.-SCHEME OF THE PUDIC ARTERY AND ITS BRANCHES.

Subpubic ligament with aperture for
dorsal vein of the penis
Apertures for dorsal artery and {
nerve of the penis
Crus penis
Aperture for artery of corpus
cavernosum
Superficial triangular ligament
Ischio-cavernosus
Aperture for artery
to bulb
Urethral aperture
Aperture for Cow-
per's duct
Position of bulb
Apertures for super-.
ficial perineal vessels
and nerve
DORSAL NERVE
Anterior layer of triangular
ligament
Dorsal artery of penis
Deep triangular
ligament
Artery of corpus
cavernosum
Artery to bulb
Pudic veins
DORSAL NERVE
POSITION OF COWPER'S
GLAND
-Internal pudic artery
Fascia of Colles,
turned backwards
Posterior border
of perineal ledge
(junction of trian-
gular ligaments
with fascia of
Colles)
through the anterior layer of the triangular ligament under the name of the dorsal
artery of the penis.
The branches of the pudic artery in the fourth part of its course are :-(a) The
artery of the bulb; (b) the artery of the crus; and (c) the dorsal artery of the penis.
(a) The artery of the bulb, often of large size, comes off from the pudic soon after
that vessel has passed between the two layers of the triangular ligament. It runs
inwards and slightly upwards behind the anterior layer of the triangular ligament,
embedded more or less in the substance of the compressor urethræ muscle. On
nearing the urethra, it passes forwards through a hole in the anterior layer of the
triangular ligament (fig. 371), by the side of the opening for the urethra, and, entering
the bulb, supplies the erectile tissue of the bulb and corpus spongiosum in the way
described under the anatomy of the urethra. It gives off a branch, just before
piercing the anterior layer of the triangular ligament, to Cowper's glands (fig. 370A).
The situation of the artery of the bulb should be remembered in performing the
operation of lateral lithotomy. As a rule, the artery is well above the central tendon
of the perinæum. If the point of the knife is entered below this spot, and care is
taken not to direct its point subsequently too much upwards so that the deeper

PUDIC-EXTERNAL ILIAC
611
part of the incision is not made higher than the superficial, the artery will not
be endangered. At times, however, the artery is given off from the pudic lower
than normal. Its division may then be unavoidable.
When the artery is given off, as it occasionally is, from the accessory pudic, it
pierces the anterior layer of the triangular ligament higher up, and is out of
danger in the ordinary low operation of lateral lithotomy. Further, the artery of
the bulb may be absent on one side, smaller than usual, or double.
In the female, the artery of the bulb, smaller than in the male, ends in the bulb
of the vestibule.
(b) The artery of the crus is usually given off from the pudic a little higher than
the artery of the bulb. It makes at once for the ramus of the pubes, perforates the
anterior layer of the triangular ligament close to the bone, and enters the crus penis
(figs. 370A, 371). This artery has to be divided in the operation for the removal of the
whole of the penis by dissecting off the crura from the rami of the pubis and ischium.
Its situation close to the bone at times gives rise to some little trouble in securing it.
In the female the artery ends in the crus clitoridis.
(c) The dorsal artery of the penis (fig. 371), the termination of the pudic, passes
upwards between the two layers of the triangular ligament in the substance of the
compressor urethræ muscle; then, turning forwards, perforates the anterior layer of
the triangular ligament, near its apex, a little to one side of the central apical
opening for the dorsal vein. It
then passes between the two layers of the suspen-
sory ligament of the penis, and descends along the dorsum of that organ, the single
centrally placed dorsal vein separating it from the artery of the opposite side. The
dorsal nerve lies to the outer side of the artery, and, still more external, the deep
external pudic branch of the common femoral artery. At the glans the dorsal
artery forms an anastomotic chain around the corona with the vessel of the
opposite side. The superficial external pudic branch of the femoral at times may
take the place of the dorsal artery.
In the female, the termination of the pudic is called the dorsal artery of the
clitoris.
The dorsal artery gives branches to-(a) The corpus cavernosum; (b) the skin of
the penis; (c) the glans penis; and in the female, (d) the glans and prepuce of the
clitoris.
THE EXTERNAL ILIAC ARTERY
The external iliac artery-the larger in the adult of the two vessels into which
the common iliac divides opposite the lumbo-sacral articulation-extends from this
spot along the brim of the pelvis, lying upon the inner border of the psoas muscle,
to the lower margin of Poupart's ligament, where, midway between the anterior
superior spine of the ilium and the symphysis pubis, it passes into the thigh, and
takes the name of the femoral.
It measures three and a half to four inches (10 cm.) in length. The course
of the vessel is indicated by a line drawn from half an inch below and a little to
the left of the umbilicus, to the centre of Poupart's ligament, that is, to a spot
midway between the symphysis pubis and the anterior superior spine of the ilium.
If this line is divided into thirds, the lower two thirds would indicate the situation
of the external iliac, the upper third the common iliac. The external iliac vein,
the continuation upwards of the femoral vein from the thigh, lies to the inner side
of the artery, but on a slightly lower plane, and just before its termination gets a
little behind the artery on the right side.
Relations. In front, the artery together with the vein is covered by the
parietal peritoneum descending from the abdomen into the pelvis, and by a layer
of condensed subperitoneal tissue, known as Abernethy's fascia. It is crossed by


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612
THE ARTERIES
the termination of the ileum on the right side, and by the sigmoid flexure on the
left. The genital branch of the genito-crural nerve runs obliquely over its lower
third, and just before its termination it is crossed transversely by the circumflex
iliac vein. The spermatic vessels lie for a short distance on the lower part of the
artery, and the vas deferens and the ovarian vessels in the female curve over
it to descend to the pelvis. It is sometimes crossed at its origin by the ureter.
The external iliac lymphatic glands lie along the course of the artery.
Behind. At first the artery lies partly upon its own vein; lower down upon
the inner border of the psoas; and just before it passes through the lacuna
vasculosa, beneath Poupart's ligament, upon the tendon of the psoas. The
continuation of the iliac into the pelvis fascia is also below it.
To its inner side is the external iliac vein, the peritoneum, the descending layer
of fascia, and the vas deferens in the male, and ovarian vessels in the female.
To its outer side is the psoas muscle and the iliac fascia.
Variations. (A) The external iliac may be longer or shorter than usual, according as
the common iliac bifurcates above or below the usual spot. When longer it often takes a
very tortuous course, making a partial loop or bend which may dip down below the brim
of the pelvis. (B) It may be much smaller in size than usual; this is especially the case
in those instances in which the femoral or main vessel of the lower limb arises from the
sciatic or other branch of the internal iliac. It then often ends in the profunda. (C) It may
give off a large branch, as the deep circumflex iliac or deep epigastric, higher than usual.
The collateral circulation is carried on (fig. 372), when the external iliac is tied, by
the anastomosis of the ilio-lumbar and lumbar arteries with the circumflex iliac; the
internal mammary with the epigastric; the obturator with the internal circumflex; the
sciatic with the internal circumflex and superior perforating; the gluteal with the external
circumflex; the arteria comes nervi ischiatici from the sciatic, with the perforating branches
of the profunda; the external pudic with the internal pudic; the pubic branch of the obturator
with the pubic branch of the epigastric.
The branches of the external iliac artery are :-(1) The deep epigastric; (2)
the deep circumflex iliac; and (3) several small and insignificant twigs to the
neighbouring psoas muscle and lymphatic glands.

(1) THE DEEP EPIGASTRIC ARTERY
The deep epigastric artery usually comes off from the external iliac just
above Poupart's ligament. Immediately after its origin, the vas deferens in the
male, and the round ligament in the female, loop round it on their way to the
pelvis, drawing, as it were, the artery slightly inwards and downwards. It
here lies internal to the inner margin of the deep or internal abdominal ring
behind the inguinal canal, and a little to the upper and outer side of the femoral
ring. Thence it passes upwards and inwards, above and to the outer side of the
superficial or external abdominal ring, lying between the fascia transversalis and
the peritoneum to the lower margin of the posterior layer of the sheath of the
rectus (fold of Douglas). Passing beneath this margin, it turns upwards between
the rectus and its sheath, lying here about midway between the outer and inner
edge of the muscle. Higher, it enters the substance of the muscle, and anastomoses
with the superior epigastric, descending in the rectus from the internal mammary.
The situation of the artery between the two abdominal rings should be borne in
mind in the operation for strangulated inguinal hernia, and its near proximity to
the upper and outer side of the femoral ring should not be forgotten in the operation
for femoral hernia. The artery is accompanied by two veins, of which the inner is
the larger. They end in a single trunk before opening into the external iliac vein.
The deep epigastric gives off the following small branches:-(a) The cremasteric,
which runs with the vas through the inguinal canal, supplies the cremaster muscle,
and anastomoses with the spermatic, inferior external pudic, and superficial perinæal
EXTERNAL ILIAC-FEMORAL
613
arteries. (b) The pubic, which passes below, or sometimes above, the femoral ring
to the back of the pubes, where it anastomoses with the pubic branch of the obtu-
rator and the corresponding vessel of the opposite side. (c) The muscular, which
supply the rectus and the oblique and transverse muscles of the abdomen, and
anastomose with the lower intercostal and the lumbar arteries. (d) The cutaneous,
which pierce the rectus, and supply the skin, anastomosing with branches of the
superficial epigastric. And (e) the terminal, which anastomose above the umbilicus
with the superior epigastric branch of the internal mammary.
Variations. (A) The epigastric may come off from the external iliac higher than usual;
it has been met with arising as much as two inches and a half above Poupart's ligament.
(B) It may arise from the femoral below Poupart's ligament, or even from the profunda.
(C) It may arise as a common trunk with the circumflex iliac. (D) It is sometimes double.
(E) It may arise from the obturator, or conversely it may give off the obturator artery.
This variation is due to the enlargement of the normal anastomosis of the epigastric and
obturator through their pubic branches. It is of considerable importance to the surgeon,
since the obturator artery, when given off from the epigastric, may run either external or
internal to the femoral ring to reach the obturator foramen. This abnormal origin of the
obturator is said to occur once in every three subjects and a half; but the abnormal artery
only courses round the inner side of the ring-in which situation it is liable to injury in
the operation for femoral hernia-in exceptional cases. According to Langton (Holden's
'Anatomy'), the chances are about seventy to one against this occurring. But even when
it takes the abnormal course, it lies a line and a half or so from the margin of the ring, and
will probably escape injury in the division of the stricture if several short notches are made
in place of a single and longer incision.

(2) THE DEEP CIRCUMFLEX ILIAC ARTERY
The deep circumflex iliac arises from the outer side of the external iliac
artery, either opposite the epigastric or a little below the origin of that vessel. It
courses upwards and outwards just above the lower margin of Poupart's ligament,
lying between the fascia transversalis and the peritoneum, or at times in a fibrous
canal formed by the union of the fascia transversalis with the iliac fascia. Near the
anterior superior spine of the ilium, it perforates the transversalis, and then courses
between that muscle and the internal oblique, along and a little above the crest of
the ilium. It finally divides into an ascending branch, which anastomoses with the
lumbar and lower intercostal arteries, and a marginal branch which runs backwards
to anastomose with the ilio-lumbar artery. It is accompanied by two veins. These
unite into one trunk, which then crosses the external iliac artery to join the external
iliac vein.
The deep circumflex iliac artery gives off the following branches:-
:-(a)
Muscular branches, which supply the psoas, iliacus, sartorius, tensor fasciæ femoris,
and the oblique and transverse muscles of the abdomen. (b) Cutaneous branches,
which supply the skin over the course of the vessel, and anastomose with the
superficial circumflex iliac, the gluteal, and the ascending branch of the external
circumflex.
Variations. (A) The circumflex iliac, like the epigastric, may be given off from the
external iliac higher than normal, though seldom if ever as high as the latter. (B) More
rarely it may come off from the femoral below Poupart's ligament. (C) It may arise as a
common trunk with the epigastric. (D) It may be double.

THE FEMORAL ARTERY
The femoral artery (fig. 372) is the continuation of the external iliac, and extends
from the lower border of Poupart's ligament, down the front and inner part of the
thigh, to the tendinous opening in the adductor magnus, through which it passes
into the popliteal space, and is then known as the popliteal. The femoral artery
614
ALSO THE ARTERIES

is at first quite superficial, being merely covered by the skin, and superficial and deep
fascia; but, after thus passing about five inches (13 cm.) in a direction downwards and
inwards through the space known as Scarpa's triangle, it sinks at the apex of that
triangle beneath the sartorius muscle, and thence to its termination continues
beneath the sartorius, coursing deeply between the vastus internus and adductor
muscles in the space known as Hunter's canal. It at first rests upon the brim of
the pelvis and head of the thigh bone, from which it is merely separated by the
capsule of the hip joint and the tendon of the psoas. Here it can be readily com-
pressed. Owing to the obliquity of the neck of the femur and the direct course
taken by the artery, it lies lower down only on muscles, at some little distance from
the bone (fig. 373). At its termination, in consequence of the shaft of the femur
inclining towards the middle line of the body, the artery lies close to the bone, but
to the inner side. The course of the vessel when the thigh is slightly flexed and
abducted the position in which the limb is placed when the vessel is ligatured-is
indicated by a line drawn from a spot midway between the anterior superior spine of
the ilium and the symphysis pubis to the adductor tubercle. When the thigh is
in the extended position and parallel to its fellow, the course of the artery will
correspond to a line drawn from the spot above-mentioned to the inner border of
the patella.
The artery for about the first inch and a half to two inches (4-5 cm.) is known as
the common femoral, but at this distance from Poupart's ligament it gives off a large
branch called the profunda, or deep femoral. For the rest of its course it is known
as the superficial femoral. The superficial femoral is only superficial where it lies
in Scarpa's triangle-that is, for about three and a half inches (9 cm.) of its course;
the remainder of the artery being deeply placed in Hunter's canal, though less
deeply than the profunda, or deep femoral. The details of the anatomy of the
femoral will perhaps best be studied by considering the relations of (1) the common
femoral; (2) the superficial femoral as it lies in Scarpa's triangle; and (3) the
superficial femoral as it lies in Hunter's canal.
(1) The relations of the common femoral artery.-In front, the common femoral
(fig. 372) is covered by the skin, the superficial fascia, the iliac portion of the fascia
lata, the crural branch of the genito-crural nerve, the superficial circumflex iliac
vein, and sometimes the superficial epigastric vein. The fascia transversalis, which
is continued downwards into the thigh beneath Poupart's ligament, is also one of
its anterior relations, but soon becomes indistinguishable from the sheath of the
vessel.
Behind, the artery rests upon the tendon of the psoas muscle, which separates
it from the brim of the pelvis and capsule of the hip joint, and, a little lower, on the
pectineus, more or less loose fat and cellular tissue intervening. The branches of
the anterior crural nerve to the pectineus muscle also pass behind it.
A similar prolongation to that derived from the fascia transversalis in front
descends behind the vessel from the iliac fascia; but, like the anterior prolongation
of fascia, soon blends with the sheath of the vessels.
To the inner side is the femoral vein, but separated from the artery in the
upper part of its course by a thin layer of fascia passing from the continuation of
the iliac fascia behind the vessels, to the continuation of the fascia transversalis
in front of the vessels.
To the outer side is the leash of nerves known as the anterior crural.
(2) The relations of the superficial femoral artery in Scarpa's triangle (fig. 372).
-In front, the artery is covered by the skin and by the superficial and deep fascia,
and is crossed at the lower part of Scarpa's triangle by a branch of the internal
cutaneous nerve. The crural branch of the genito-crural nerve is superficial to it,
but is separated from this part of the femoral artery by the deep fascia.
Behind, the artery lies on the pectineus, from which it is separated by the femoral



FEMORAL
615
vein and the profunda vein and artery. Lower down, it lies on the upper portion
of the adductor longus muscle.
To its outer side is the long saphenous nerve and the nerve to the vastus internus,
the anterior crural nerve having in this situation more or less broken up into its
components.
To its inner side is the femoral vein, which, however, at the apex of Scarpa's
triangle, is getting somewhat behind the artery.
FIG. 372.-THE FEMORAL ARTERY IN SCARPA'S TRIANGLE.
(From a dissection by W. J. Walsham in St. Bartholomew's Hospital Museum.)
Common iliac artery
SYMPATHETIC NERVE
Middle sacral artery
Common iliac vein.
URETER.
Internal iliac artery
External iliac vein
External iliac artery
Posterior br. of internal iliac dividing,
into gluteal and ilio-lumbar arteries
Lateral sacral artery
SACRAL PLEXUS
OBTURATOR NERVE
Obturator artery
Obliterated hypogastric
Superior vesical artery
Edge of levator ani
Pudic artery
BLADDER
Middle vesical artery
Deep epigastric artery
Pubic br. of epigastric
artery
Common femoral artery
Long saphenous vein
Pectineus muscle-
Obturator artery.
Adductor magnus.
Internal circumflex artery-
Adductor brevis
OBTURATOR NERVE (ant. branch)
Profunda artery-
Adductor longus, hooked aside
Superficial femoral artery and vein
Gracilis muscle
Lower part of sartorius.
Psoas muscle
Ilio-lumbar artery
EXTERNAL CUTANEOUS
NERVE
Iliacus muscle
GENITO-CRURAL NERVE
- ANTERIOR CRURAL NERVE
DO STOW
до Бол
Deep circumflex iliac artery
Superficial circumflex iliac artery
ANTERIOR CRURAL NERVE
Gluteal artery and nerve
Gee Tensor fasciæ femoris, hooked
aside
Gluteus medius and minimus
Sartorius muscle
MIDDLE CUTANEOUS NERVE
NERVE TO RECTUS
NERVE TO VASTUS
EXTERNUS
External circumflex artery
NERVE TO CRUREUS
Rectus, hooked aside
Profunda vein
LONG SAPHENOUS
AND
NERVE
NERVE TO VASTUS
INTERNUS
od of
Vastus internus muscle
The superficial femoral varies in length according to the distance that the pro-
funda is given off from the common femoral below Poupart's ligament. As a rule,
it measures three inches and a half (9 cm.), the common an inch and a half (4 cm.).
But the profunda may come off two or more inches below Poupart's ligament, in
which case the superficial femoral will be shorter to this extent; or it may come off
less than an inch and a half below Poupart's ligament, or even from the external
iliac above Poupart's ligament, when the superficial will be longer than normal. The
616
THE ARTERIES
practical point to remember is that it is more usual to meet with a short than with
a long common femoral, and that, if the superficial femoral is tied at the apex of
Scarpa's triangle-i.e. the spot where the inner edge of the sartorius comes into
contact with the adductor longus-there is nearly always a sufficient length of that
vessel above the ligature to ensure a firm internal clot, and consequently, as far as
this point is concerned, a successful result.
(3) The relations of the superficial femoral artery in Hunter's canal.-Hunter's
canal is the somewhat triangularly shaped space bounded by the vastus internus
on the outer side, the adductors longus and magnus on the inner side, and by an apo-
neurosis thrown across from the adductors to the vastus in front. Below, the canal
terminates at the opening in the adductor magnus; above, its limit is less well
defined, as here the aponeurosis between the muscles becomes less tendinous, and
gradually fades away into the perimuscular fascia.
into the perimuscular fascia. The transverse direction of the
fibres of the aponeurotic covering at the lower two-thirds of the canal is character-
istic, and serves as a rallying point in tying the artery in this part of its course.
Lying superficial to the aponeurosis is the sartorius muscle. The superficial
femoral artery as it lies in this canal has the following relations:-
In front, in addition to the skin, superficial and deep fascia, are the sartorius
muscle and the aponeurotic fibres of the canal. The internal saphenous nerve
crosses the artery from without inwards, lying in the wall of the canal.
Behind is the angle of meeting of the vastus internus and the adductors.
The femoral vein lies behind the artery, but gets a little external to it at the lower
part of the canal. It is here very firmly and closely attached to the artery, embracing
it as it were on its posterior and external aspect. Hence it is very liable to be
punctured on ligaturing the artery in this part of its course. Such an accident is
best avoided by opening the sheath of the vessels well to the inner side of the front
of the artery, and by keeping the point of the aneurysm needle closely applied to
the vessel in passing it from without inwards between the vein and the artery.
There are sometimes two veins, which then more or less surround the artery.
To its inner side is the adductor longus above and the adductor magnus below.
To its outer side is the vastus internus, and at the lower part of the canal the
femoral vein.
Variations in the Femoral Artery
The most important variations in the femoral artery are:-(A) The femoral arising
from the sciatic or internal iliac, and passing out of the pelvis and down the back of
the thigh with the great sciatic nerve to the popliteal space; the external iliac under these
circumstances ending in the profunda or external circumflex, or some other branch of
the femoral. (B) A double condition of the femoral artery below the origin of the profunda;
the vessel re-uniting lower down the thigh. (C) A vas aberrans given off from the inner
side of the common femoral or external iliac, and joining the femoral lower down. (D) The
vein may remain to the inner side of the artery its whole distance through the thigh, or it
may be double, especially in Hunter's canal. There is often a plexiform arrangement of
the vein around the artery in this situation. (E) The variations in the origin of the profunda
have been already mentioned.

BRANCHES OF THE FEMORAL ARTERY
The femoral artery gives off the following branches :-
A. From the common femoral :-(1) The superficial epigastric; (2) the superficial
circumflex iliac; (3) the superficial external pudic; (4) the deep external pudic;
and (5) the profunda.
B. From the superficial femoral in Scarpa's triangle :-(1) Muscular branches
and (2) the saphenous branch.
;
C. From the superficial femoral in Hunter's canal:-(1) Muscular branches; and
(2) the anastomotica magna.

FIG. 373.-TO SHOW THE ANASTOMOSES OF THE ARTERIES OF THE LOWER EXTREMITY.
(After Smith and Walsham.)
Deep epigastric artery.
Ilio-lumbar artery
Deep circumflex iliac,
artery
Gluteal artery-
Common femoral artery.
Profunda artery
External circumflex.
artery
Crucial anastomosis
Abdominal aorta
-Common iliac artery
Middle sacral artery
Internal iliac artery
External iliac artery
Obturator artery
Sciatic artery
Pudic artery
Internal circumflex artery
Superficial femoral artery
Perforating branches of profunda
Popliteal artery.
Superior external articular.
Anastomotica magna
Terminal branch of profunda
anastomosing with popliteal
Superior internal articular
Inferior external articular
External lateral ligament-
Tibial recurrent-
Anterior tibial artery.
Internal lateral ligament
Inferior internal articular
Posterior tibial artery
Peroneal artery
External malleolar branch
Anterior peroneal artery
Posterior peroneal artery
External plantar artery
Internal malleolar branch
Tarsal branch
Dorsalis pedis artery
Metatarsal branch
618
THE ARTERIES
A. Branches of the Common Femoral
(1) The superficial epigastric artery comes off from the femoral about half
an inch below Poupart's ligament. At its origin it is beneath the fascia lata,
but almost at once passes through this fascia, or else through the saphenous
opening, and courses upwards and inwards in front of the external oblique muscle
almost as far as the umbilicus. It ends in numerous small twigs, which anasto-
mose with the cutaneous branches from the deep epigastric and internal mammary.
In its course it gives off small branches to the inguinal glands and to the skin and
superficial fasciæ. Running with it is the superficial epigastric vein, which ends
in the long saphenous just before the latter passes through the saphenous opening.
(2) The superficial circumflex iliac artery (fig. 372), usually smaller than the
superficial epigastric, arises either in common with that vessel, or else as a separate
branch from the femoral. It passes upwards and outwards over the iliacus, and, soon
perforating the fascia lata a little to the outer side of the saphenous opening, runs
more or less parallel to Poupart's ligament about as far as the crest of the ilium,
where it ends in branches which anastomose with the deep circumflex iliac artery.
In its course it gives off branches to the iliacus and sartorius muscles, to the inguinal
glands, and to the fascia and skin. Its companion vein, the superficial circumflex
iliac, ends in the long saphenous vein just before the latter passes through the saphe-
nous opening.
(3) The superficial or superior external pudic artery arises from the inner
side of the femoral, either a little above or else in common with the deep or inferior
external pudic. It passes either through the fascia lata, or else through the cribri-
form fascia covering the saphenous opening, ascends upwards and inwards over the
spermatic cord in the male, or round ligament in the female, and divides into
branches, one of which supplies the integuments above the pubes, while another
descends along the penis external to the dorsal artery, with which, and with the
corresponding artery of the opposite side, it anastomoses at the corona. In the
female, this branch terminates in the preputium clitoridis, anastomosing with
the dorsal artery of that organ. Small branches also descend to the scrotum and
labium respectively. As it crosses the cord it anastomoses with the cremasteric
branch of the deep epigastric. It is accompanied by two small veins, which
usually join to form a single vein opening into the upper end of the long saphenous.
(4) The deep or inferior external pudic artery arises from the inner side of the
femoral artery, either in common with the preceding branch or a little lower down.
It runs inwards beneath the deep fascia, across the pectineus and adductor longus
muscles, and, perforating the fascia close to the ramus of the pubes, supplies
the skin of the scrotum or the corresponding part, the labium major, in the
female, anastomosing with the superficial perinæal branch of the internal pudic.
It supplies small twigs to the pectineus and adductor muscles as it crosses them.
Its companion veins terminate as a single trunk in the long saphenous.
(5) The profunda or deep femoral artery (figs. 372, 373) is the chief nutrient
vessel of the thigh. It is usually given off from the back and outer part of the
common femoral, about an inch and a half (4 cm.) below Poupart's ligament. At
first it is a little external to the femoral, but as it runs downwards and backwards
it gets behind that artery and closer to the bone. On reaching the
upper border
of the adductor longus muscle, it leaves the femoral, and, passing beneath the
muscle, pierces the adductor magnus, and finally, much reduced in size, ends in the
hamstring muscles.
Relations Behind, the artery lies successively upon the iliacus, the pectineus,
the adductor brevis, and adductor magnus muscles. In front, at first it is
superficial, being merely covered by the skin, superficial and deep fasciæ, and
branches of the anterior crural nerve; but as it sinks behind the femoral artery, it has

BRANCHES OF COMMON FEMORAL
619
in front of it both the femoral and the profunda veins, and lower down the adductor
longus muscle. Externally, it is separated from the bone by the vastus internus.
Internally are the pectineus and the angle of meeting of the adductor brevis and
adductor magnus muscles.
Branches of the profunda. The profunda gives off the following branches :-
(a) The external circumflex; (b) the internal circumflex; and (c) the three per-
forating. The termination of the artery is sometimes called the fourth perforating
branch.
(a) The external circumflex, a short trunk, but the largest in diameter of the
branches of the artery, arises from the outer side of the profunda as it lies on the
iliacus muscle, about three-quarters of an inch (2 cm.) below the origin of that vessel
from the femoral. It passes transversely outwards over the iliacus, under the
sartorius and rectus, and between the branches of the anterior crural nerve. In
this course it gives off branches to the rectus and crureus, and then divides into
three chief sets of branches-an ascending, transverse, and descending.
(i) The ascending branch, consisting of one or more separate vessels, runs
upwards beneath the sartorius; then, sinking deeply beneath the tensor fasciæ
femoris on the outer side, and the gluteus medius and minimus on the inner side,
anastomoses with the superior gluteal and the deep circumflex iliac arteries. This
branch also supplies a twig which runs upwards under the rectus to the hip
joint.
(ii) The transverse branch, or branches, run transversely outwards, and, winding
over the crureus and piercing the vastus externus, anastomose towards the back
of the thigh with the superior perforating branch of the profunda, the sciatic, and
internal circumflex arteries. These branches will usually be found a little below
the great trochanter.
(iii) The descending branches run directly downwards along with the nerve to
the vastus externus muscle. They lie beneath the rectus muscle and on the
crureus or vastus externus, some of them being just under cover of the anterior
edge of the latter muscle. They are distributed to the vastus externus, crureus,
and rectus, one branch usually running along the anterior border of the vastus
externus as far as the knee joint, where it anastomoses with the superior external
articular branch of the popliteal (fig. 376); another, entering the crureus, anasto-
moses with the lower perforating branch of the profunda and with the anastomotica
magna.
Variations of the external circumflex.-(A) It may come off from the femoral above the
profunda. (B) It may be double, one branch coming off from the femoral, and one from the
profunda, or both from the profunda, or both from the femoral above the profunda.
(b) The internal circumflex artery comes off from the back and inner part of
the profunda artery on about the same level as the external circumflex; sometimes
as a common trunk with that vessel. As it winds round the inner side of the
femur to reach the region of the trochanters, it lies successively, first, between the
psoas and pectineus, then between the obturator externus and adductor brevis; finally,
between the adductor magnus and quadratus femoris, where it anastomoses with
the external circumflex externally, with the sciatic above, and with the superior per-
forating below, forming the so-called crucial anastomosis. As it passes between the
obturator externus and adductor brevis, it gives off two or more branches to the
adductor longus, the adductor brevis, the gracilis, and the obturator externus, and
anastomoses with the obturator artery. Another small branch usually courses
upwards and outwards beneath the tendon of the psoas, and enters the hip joint
beneath the transverse ligament, and, together with the articular branch of the
obturator, supplies the fatty tissue in the acetabulum, and sends branches to the
synovial membrane. As it lies beneath the adductor brevis, it gives off a descending

620
THE ARTERIES
branch to the adductor magnus and brevis. This branch is generally accompanied
by the posterior division of the obturator nerve. Before passing between the
quadratus femoris and adductor magnus, a small branch runs upwards beneath the
quadratus femoris to supply the back of the hip joint, and anastomoses with the
gluteal and sciatic arteries. Its companion veins join the profunda vein.
Variations of the internal circumflex.-(A) It may come off from the profunda artery
before the external circumflex. (B) It may arise from the femoral artery; or (C) from the
external iliac or one of its branches.
(c) The perforating arteries of the profunda are so called because they perforate,
in a more or less regular manner from above downwards, certain of the adductor
muscles. They form a series of loops by anastomosing with one another
(fig. 373), and with the gluteal, internal circumflex, and sciatic arteries above,
and with the muscular and articular branches of the popliteal below. They are
distributed chiefly to the hamstring muscles, but send twigs along the external
intermuscular septum to supply the integuments at the back and outer parts of
the thigh.
Other branches perforate the external intermuscular septum and
the short head of the biceps, and, entering the crureus and vastus externus,
anastomose with the descending branch of the external circumflex. All the per-
forating arteries, moreover, contribute to reinforce the artery of the sciatic nerve,
a branch of the sciatic artery. They are each accompanied by two veins which
terminate in the profunda.
(i) The superior or first perforating is given off from the profunda as that
vessel sinks beneath the adductor longus. It either pierces the adductor brevis,
or else runs between the pectineus and adductor brevis, and then passes through
a small aponeurotic opening in the adductor magnus close to the inner lip of the
linea aspera. In this course it supplies branches to the adductors, and, after
perforating the adductor magnus, is distributed to the lower part of the gluteus
maximus and the hamstring muscles, one branch commonly running upwards
beneath the gluteus maximus to anastomose with the external circumflex, internal
circumflex, and sciatic arteries, forming the crucial anastomosis at the junction of
the neck of the femur with the great trochanter (fig. 373). A second branch descends
to anastomose with the ascending branch of the middle perforating.
(ii) The middle or second perforating, which is given off from the profunda as
it lies behind the adductor longus, pierces the adductor brevis, and then passes
through a second aponeurotic opening in the adductor magnus a little below that
for the first perforating artery, and also close to the linea aspera. It supplies the
hamstring muscles, sends a branch upwards to anastomose with the descending
branch of the superior perforating, and another downwards to anastomose in
like manner with the ascending branch of the third perforating. It usually
supplies the chief nutrient branch to the femur. At times, however, this comes
from the third perforating.
(iii) The inferior or third perforating also arises from the profunda as it lies
under the adductor longus, usually about the level of the lower border of the adductor
brevis. It turns beneath this border, and then, like the first and second perforating,
passes through an aponeurotic opening in the adductor magnus close to the linea
aspera. It also supplies the hamstring muscles, and divides into two branches,
which anastomose above with the second perforating, and below with the termination
of the profunda or the fourth perforating.
(iv) The fourth perforating is the continuation of the profunda. It passes
through an aponeurotic opening in the adductor magnus just above the opening
for the femoral artery. It anastomoses, above with the third perforating, and below
with the superior muscular and articular branches of the popliteal. It supplies
chiefly the short head of the biceps.
POPLITEAL
621
B. Branches of the Superficial Femoral in Scarpa's Triangle
The branches given off by the superficial femoral in Scarpa's triangle are
usually small and insignificant. They are:-(1) Muscular, to the sartorius and
rectus; and (2) saphenous, to the region of the long saphenous vein and femoral
lymphatics in the neighbourhood of the vein.
C. Branches of the Superficial Femoral in Hunter's Canal
The branches in Hunter's canal are:-(1) Muscular; and (2) the anastomotica
magna.
(1) The muscular branches supply the sartorius, the rectus, the vastus internus,
the crureus, and the adductor muscles. They are usually larger than the muscular
branches given off in Scarpa's triangle.
(2) The anastomotica magna arises from the front and inner side of the femoral
just before the latter perforates the adductor magnus muscle, and almost immedi-
ately divides into two branches, (a) a superficial and (b) a deep. These branches
may sometimes come off separately from the femoral.
(a) The superficial branch pierces the aponeurotic covering of Hunter's canal,
passes between the sartorius and gracilis muscles along with the internal saphenous
nerve, and, perforating the deep fascia, supplies the skin of the upper and inner side of
the leg and anastomoses with the inferior internal articular branch of the popliteal
and the other vessels forming the plexus or rete at the inner side of the knee. In
its course it gives twigs to the lower part of the sartorius and gracilis muscles.
(b) The deep branch runs downwards in front of the adductor magnus tendon,
burrowing amongst the fibres of the vastus internus as far as the internal condyle,
where it passes into the plexus or rete on the inner side of the knee joint,
anastomosing with the internal inferior articular banch of the popliteal, the
anterior tibial recurrent, and the external superior articular branch of the popliteal
across the front of the femur just above the articular surface of the knee joint. In
common with the rest of the rete it sends branches into the knee joint. It also
supplies branches to the vastus internus and crureus muscles.

THE POPLITEAL ARTERY

The popliteal artery (fig. 375) runs through the popliteal space or ham. It is
a continuation of the femoral, and extends from the aponeurotic opening in the
adductor magnus at the junction of the middle with the lower third of the thigh
to the lower border of the popliteus muscle, where it terminates by dividing into
the posterior and anterior tibial arteries. This division is on a level with the lower
border of the tubercle of the tibia. As the artery passes through the opening
in the adductor magnus, it is accompanied by the popliteal vein, and at times
by the branch of the obturator nerve to the knee joint. The vein throughout
is behind the artery, at first lying a little external to it, but as the vessels pass
through the popliteal space the vein crosses obliquely over the artery, and at
the termination of the artery lies a little to its inner side. The internal popliteal
nerve is superficial to both artery and vein. As it enters the space it is well to the
outer side of the vessels, but as it descends it gradually approaches them, crosses
behind them, and at the lower part of the space lies to their inner side. The
artery in the whole of its course is deeply placed and covered by a considerable
amount of fat and cellular tissue.
Relations (fig. 374).-In front, the artery lies successively on the popliteal
surface of the femur (from which it is separated by a little fat and sometimes one
or two small glands); on the posterior ligament of the knee; on the hinder edge of the


622
THE ARTERIES
articular surface of the head of the tibia; and on the popliteus muscle. From the
latter muscle it is separated by the expansion from the semi-membranosus which
covers the muscle, and is attached to the oblique line on the tibia.
FIG. 374.-RELATIONS OF THE POPLITEAL ARTERY TO BONES AND MUSCLES.
Superior external articular artery
POPLITEAL NERVE
External lateral ligament
Inferior external articular artery
Superior internal articular artery
Popliteal artery
Posterior ligament of knee
Azygos articular artery
SEMI-MEMBRANOSUS
Muscular branch to soleus.
Soleus
Anterior tibial artery
Peroneus longus-
Peroneal artery.
BRANCH OF POSTERIOR TIBIAL-
NERVE TO FLEXOR LONGUS
HALLUCIS
Flexor longus hallucis.
Inferior internal articular artery
Muscular branch
Tibialis posticus
POSTERIOR TIBIAL NERVE
-MUSCULAR BRANCH OF
POSTERIOR TIBIAL NERVE
TO FLEXOR LONGUS
DIGITORUM
Flexor longus digitorum
Posterior tibial artery
Cutaneous branch of peroneal artery-
Peroneus brevis-
Continuation of peroneal artery.
OS CALCIS
ent
Tibialis posticus
Communicating branch
Internal annular ligament
Internal calcaneal artery
Behind, the artery is covered, above by the semi-membranosus; in the centre of
the space by the skin, superficial and deep fascia; and below by the inner head of the

POPLITEAL
623
gastrocnemius. The popliteal vein is behind it in the whole of its course. The
internal popliteal nerves cross behind it obliquely from without inwards, about the
centre of the space. As the artery divides into the anterior and posterior tibial,
it is crossed by the aponeurotic arch of the soleus which stretches between the
tibial and fibular origins of that muscle.
To the inner side are the semi-membranosus above, and the inner head of the
gastrocnemius and the internal popliteal nerve below.
To the outer side are the biceps and the internal popliteal nerve above, and
the outer head of the gastrocnemius and the plantaris below.
FIG. 375.-SIDE VIEW OF THE POPLITEAL ARTERY.
INTERNAL
SAPHENOUS NERVE-
BRANCHES OF THE
INTERNAL CUTA-
NEOUS NERVE
Sartorius
Insertion of adductor.
magnus
Anastomotica magna-
artery
LONG SAPHENOUS
NERVE
Vertical fibres of the
adductor magnus
Popliteal artery
Vastus internus
Cut edge of fascia lata
BRANCH OF SAPHE-
NOUS NERVE TO
PATELLAR PLEXUS
Internal saphenous
vein
Gracilis
Part of
semi-tendinosus
Principal variations in the popliteal.-(A) It may divide higher, or more rarely lower
than usual. (B) It may divide into the anterior tibial and peroneal. (C) The vein may
be deeper than the artery, or separated from it by a slip of the gastrocnemius.
BRANCHES OF THE POPLITEAL ARTERY
The branches of the popliteal may be divided into-(1) The cutaneous; (2) the
muscular or sural; (3) the articular; and (4) the terminal.
624
THE ARTERIES
(1) The cutaneous branches-very irregular in their origin, number, and dis-
tribution-arise either from the main trunk or from one of the inferior muscular
branches, pass downwards between the two heads of the gastrocnemius, and, per-
forating the deep fascia, supply the skin and fascia of the calf. A branch, usually
of moderate size, accompanies the short or external saphenous vein, and is
sometimes called the posterior saphenous artery.
(2) The muscular or sural branches are commonly divided into the superior
and inferior. They arise from the upper and lower portions of the popliteal
respectively; the former supply the muscles forming the boundaries of the upper
half of the popliteal space; the latter, the muscles of the calf.
(a) The upper muscular branches or superior sural, as they are sometimes
called-are distributed to the hamstring muscles and lower part of the adductor
magnus. They anastomose with the superior articular arteries, and with the
termination of the profunda. (b) The inferior muscular or sural branches, usually
two in number and of large size, come off from the popliteal just as it passes under
cover of the inner head of the gastrocnemius. They at first descend between the
two heads of the latter muscle, one branch then entering the outer, and one the
inner head. They also supply branches to the soleus and plantaris muscles.
(3) The articular, five in number, are divided into two superior (internal and
external), two inferior (internal and external), and the azygos, or anterior. The
superior and inferior come off transversely in pairs from either side of the
popliteal, the superior above, the inferior below the joint, and, winding round
the bones to the front of the knee, form-by anastomosing with each other and with
the anastomotica magna, the termination of the profunda, the descending branch of
the external circumflex, and the anterior tibial recurrent a superficial and deep
arterial rete (fig. 376). The superficial anastomosis or rete lies between the skin and
fascia round about the patella (patellar rete), which it supplies, the larger branches
entering it from above. The deep anastomosis or rete lies on the surface of the
bones around the articular surfaces of the femur and tibia, supplying branches to the
contiguous bones and to the joints. The azygos articular is a single short trunk
coming off from the deep surface of the popliteal artery. It at once passes through
the posterior ligament into the joint.
(a) The superior external articular, the larger of the two superior articular
branches, runs transversely outwards under the external head of the gastrocnemius,
and, passing beneath the biceps and through the external intermuscular septum and
vastus externus, enters the substance of the crureus, and anastomoses, above with
the descending branch of the external circumflex, below with the inferior external
articular, and across the front of the femur with the superior internal articular,
the anastomotica magna, and termination of the profunda, forming with them, as
already described, the deep periarticular rete. Branches are given off to the patella, to
the upper and outer part of the joint, to the bone, and to the contiguous muscles.
(b) The superior internal articular (fig. 374) runs transversely inwards just
above the inner head of the gastrocnemius, beneath the semi-membranosus, and, after
perforating the tendon of the adductor magnus, enters the substance of the vastus
internus, where it anastomoses (fig. 376) with the deep branch of the anastomotica
magna and termination of the profunda above, with the inferior internal articular
below, and with the superior external articular across the front of the femur. It
supplies small branches to the contiguous muscles, to the femur, to the patella,
and to the joint.
(c) The inferior internal articular, the larger of the two inferior articular
arteries, passes obliquely downwards and inwards across the popliteus, below the
internal tuberosity of the tibia, and beneath the internal lateral ligament to the
front and inner side of the knee joint, where it anastomoses (fig. 376), above with
the superior internal articular and the superficial branch of the anastomotica magna,

BRANCHES OF POPLITEAL
625
and across the front of the tibia with the inferior external articular. It supplies
branches to the lower and inner part of the joint.
(d) The inferior external articular (fig. 376) passes outwards above the head of
the fibula, along the tendon of the popliteus muscle, beneath the external head of the
gastrocnemius, and then under the tendon of the biceps, and between the long and
short external lateral ligaments. Then winding to the front of the joint, it anasto-
moses above with the superior external articular, below with the anterior tibial
recurrent, and across the front of the tibia with the internal inferior articular. It
also supplies branches to the outer and lower part of the joint.
FIG. 376.-THE ANASTOMOSIS ABOUT THE KNEE JOINT.
(Semi-diagrammatic.)
Deep branch of anastomotica.
magna
Superficial branch of anastomotica-
magna
Adductor magnus-
Superior internal articular artery
piercing tendon of adductor
magnus
Internal lateral ligament
Inferior internal articular artery
Posterior tibial artery
Descending branch of external
circumflex artery
Superior external articular artery
passing through external inter-
muscular septum
-EXTERNAL CONDYLE
PATELLA
Long external lateral ligament
Inferior external articular artery
Anterior tibial recurrent artery
Anterior tibial artery
(e) The azygos articular arises from the deep surface of the popliteal artery,
and passes, with the articular branch of the obturator nerve, through the posterior
ligament, directly into the knee joint, where it supplies the crucial ligaments, and the
ligamenta mucosa and alaria. It anastomoses with the intrinsic branches of the
other articular arteries.
(4) The terminal branches of the popliteal are the posterior and anterior tibial
arteries. The former appears to be a direct continuation of the vessel, and passes
down the back of the leg to the inner ankle, where, on entering the sole of the foot,
it divides into the internal and external plantar. The anterior tibial turns forwards,
and, passing through the interosseous membrane, descends along the front of the
leg, and ends, under the name of the dorsal artery of the foot, by anastomosing,
through the first interosseous space, with the external plantar artery in the sole.
SS

626
THE ARTERIES
THE POSTERIOR TIBIAL ARTERY
The posterior tibial artery (fig. 377), the larger of the two branches into which the
popliteal divides at the lower border of the popliteus muscle, runs downwards on
the flexor aspect of the leg between the superficial and deep muscles to the back of
the inner ankle, where, midway between the tip of the internal malleolus and os
FIG. 377.-THE POPLITEAL, THE POSTERIOR TIBIAL, AND THE PERONEAL ARTERY.
Semi-tendinosus.
Semi-membranosus.
Sartorius.
Inferior internal articular artery-
Gracilis.
Inner head of gastrocnemius,.
hooked aside
Inferior sural artery.
Superior external articular artery
Biceps
-Superior sural artery
Popliteal artery
Popliteus muscle
Inferior external articular artery
Soleus-
Tibialis posticus-
Soleus, turned back-
Posterior tibial artery-
Flexor longus digitorum-
-Gastrocnemius and soleus
Peroneal artery
Flexor longus hallucis
FIBULA
Tibialis posticus-
Flexor longus digitorum-
Communicating artery.
-Anterior peroneal artery
Peroneus longus
Communicating artery
calcis, and under cover of the origin of the abductor hallucis as it arises from the
internal annular ligament, it divides into the internal and external plantar arteries.
The artery is first situated midway between the tibia and fibula, and is deeply
placed beneath the muscles of the calf. As it passes downwards it inclines inwards,
and at the lower third of the leg is superficial, being only covered by the skin and
88

POSTERIOR TIBIAL
627
fascia. At the ankle it lies beneath the internal annular ligament, and at its bifur-
cation also beneath the abductor hallucis. A line drawn from the centre of the
popliteal space to a spot midway between the internal malleolus and point of the heel
will indicate its course.
Relations. Anteriorly, from above downwards, it lies successively on the tibialis
posticus, the flexor longus digitorum, the posterior surface of the tibia, and the
internal lateral ligament of the ankle joint.
Posteriorly, it is covered by the skin and fascia, the gastrocnemius and soleus,
and the deep or intermuscular fascia of the leg, by which it is tightly bound down
to the underlying muscles. It is crossed by the posterior tibial nerve about an
inch and a half below its origin and after it has given off its peroneal branch, the
nerve first being on the inner, and for the rest of its course on the outer side of the
vessel (fig. 374). It is accompanied by two veins, which send numerous anasto-
mosing branches across it. In the lower third of the leg the artery is superficial,
being only covered by the skin and by the superficial and deep fasciæ.
At the inner ankle it lies beneath the internal annular ligament and abductor
hallucis upon the internal lateral ligament of the ankle joint. Here it has the
tibialis posticus and flexor longus digitorum in front of it, and the posterior tibial
nerve and the flexor longus hallucis behind and to its outer side.
At times the posterior tibial nerve divides higher than usual, when one branch
lies on the inner side of the artery, and the other branch on the outer side.
The branches of the posterior tibial artery are:-(1) The peroneal; (2) the
muscular; (3) the medullary; (4) the cutaneous; (5) the communicating; (6) the
malleolar; (7) the calcanean, or internal calcanean; and (8) the terminal, i.e. the
external and internal plantar arteries.
(1) The peroneal artery (figs. 374, 377) arises from the posterior tibial about one
inch below the lower border of the popliteus muscle. At first forming a gentle
curve with the convexity outwards, it approaches the fibula, and continues its course
downwards close to that bone as far as the lower end of the interosseous membrane,
where it gives off a large branch, the anterior peroneal, and then, passing over the
back of the inferior tibio-fibular joint, terminates by breaking up into a network,
which is distributed over the back of the external malleolus and outer surface of
the calcaneum (fig. 381). It is accompanied by two venæ comites.
Relations. At its upper part it is deeply placed between the tibialis posticus
and soleus muscles, and beneath the deep or intermuscular fascia. For the rest of
its course to the ankle it lies beneath, or sometimes in the substance of the flexor
longus hallucis in the angle between the fibula and interosseous membrane. After
giving off the anterior peroneal, it is only covered, as it lies behind the tibio-fibular
articulation, by the integuments and deep fascia, and in this part of its course is
sometimes called the posterior peroneal.
The branches of the peroneal artery are:-(a) The anterior peroneal; (b) the
muscular; (c) the medullary; (d) the communicating; (e) the cutaneous; (f) the
external calcanean; and (g) the terminal.
(a) The anterior peroneal artery arises from the front of the peroneal artery
at the lower part of the interosseous space, and, passing through the interosseous
membrane, runs downwards over the front of the inferior tibio-fibular joint, beneath
the peroneus tertius, and supplies this muscle and the inferior tibio-fibular joint. It
anastomoses with the tarsal, metatarsal, and external malleolar branches of the
anterior tibial artery, and with the external plantar artery on the outer side of the
foot, forming a plexus over the outer ankle (fig. 380).
(b) The muscular branches of the peroneal artery are distributed to the con-
tiguous muscles, namely: the flexor longus hallucis, the tibialis posticus, the
peronei, and the soleus.
(c) The medullary enters the nutrient foramen of the fibula.


Ss2
628
THE ARTERIES
(d) The communicating branches pass transversely inwards in front of the
tendo Achillis to anastomose with the communicating branch of the posterior
tibial. The usual situation of this communication is from one to two inches above
the ankle joint.
(e) The cutaneous branches run outwards between the flexor longus hallucis and
soleus to supply the integuments on the outer side of the leg.
(f) The external calcanean comes off from the peroneal below the point at
which the anterior peroneal is given off, and is distributed over the outer surface of
the os calcis.
(g) The terminal branch, or posterior peroneal, the continuation of the peroneal
artery, anastomoses with the other arteries distributed to the external malleolus
and heel.
(2) The muscular branches of the posterior tibial artery are distributed to the
contiguous muscles, namely: the tibialis posticus, flexor longus digitorum, and soleus.
(3) The medullary artery, a vessel of large size, leaves the posterior tibial at
its upper part, pierces the tibialis posticus, and enters the medullary foramen in
the upper third of the posterior surface of the tibia. In the interior of the bone
it divides into two branches: an ascending or smaller, which runs upwards
towards the head of the bone; and a descending or larger, which courses downwards
towards the lower end. It gives off two or three muscular twigs to the tibialis
posticus before it enters the foramen. The medullary artery of the tibia is the
largest nutrient artery of bone in the body.
(4) The cutaneous branches pass outwards to the integuments on the inner
side of the leg. They run in the cellular planes between the deep and superficial
muscles, and serve as useful guides to the vessel when ligaturing the posterior
tibial through the lateral incision.
(5) The communicating branch arises from the posterior tibial about two
inches above the inner malleolus, and, passing transversely outwards across the
tibia beneath the flexor longus hallucis and tendo Achillis, anastomoses with the
communicating branch of the peroneal.
Frequently an inferior communicating branch between the posterior tibial and
peroneal arteries is likewise present in the loose connective tissue beneath or
behind the tendo Achillis (fig. 374).
(6) The malleolar or internal malleolar branches are distributed, as the name
implies, over the internal malleolus, anastomosing with the other arteries entering
into the retiform plexus of vessels over that portion of bone. In their course to
the malleolus, they run beneath the flexor longus digitorum and tibialis posticus
muscles. idis
(7) The calcanean or internal calcanean branch is distributed to the soft parts
over the inner side of the calcaneum. This branch-or, as is frequently the case,
branches comes off from the posterior tibial just before its bifurcation, and anasto-
moses with the internal malleolar and peroneal arteries (fig. 379).
(8) The terminal branches are the external and internal plantar arteries.



THE EXTERNAL PLANTAR ARTERY
The external plantar artery-the larger of the two branches into which the
posterior tibial divides beneath the internal annular ligament-passes at first
obliquely forwards and outwards across the sole of the foot to the base of the fifth
metatarsal bone, where it makes a bend forwards and inwards, and, sinking deeply
into the foot, terminates at the proximal end of the first interosseous space by
anastomosing with the communicating branch of the dorsal artery of the foot. In its
course to the fifth metatarsal bone the artery runs in a more or less straight line

EXTERNAL PLANTAR
629
obliquely across the foot; whilst its deep portion, extending from the fifth metatarsal
bone to the proximal end of the first interosseous space, forms a slight curve with
the convexity forwards, and is known as the plantar arch. The plantar arch is
comparable to the deep palmar arch formed by the deep branch of the ulnar
anastomosing with the radial through the first interosseous space. This homology
is at times more complete in that the communicating branch of the dorsalis pedis,
the homologue of the radial in the upper limb, takes the chief share in forming the
arch. The external plantar artery is accompanied by two veins. The course of
FIG. 378. THE PLANTAR ARTERIES.
(From a dissection in the Museum of St. Bartholomew's Hospital.)
External calcanean artery
Cutaneous branch of external-
plantar
-Internal calcanean artery
Cutaneous branch of internal
plantar
Abductor minimi digiti
Abductor hallucis
Anastomotic branch
External plantar artery
Internal plantar artery
-Flexor brevis digitorum
First digital to outer side of
little toe
Lumbrical muscle
Second digital
Third digital
Fourth digital
-Branch of internal plantar to
digital arteries (superficial
digital)
Flexor brevis hallucis
Anastomosis about inter-
phalangeal joint
Dorsal branch of collateral
digital
Anastomosis of collateral digital.
arteries around matrix of nail
and pulp of toe
Princeps hallucis, or fifth plantar
digital artery
Collateral digital branch of
princeps hallucis
Collateral digital branch of
princeps hallucis to inner side
of great toe
Collateral digital branch of
princeps hallucis
the artery is indicated by a line drawn across the sole of the foot from a point
midway between the tip of the internal malleolus and the greater tubercle of the
calcaneum to the base of the fifth metatarsal bone, and thence forwards and inwards
to the posterior part of the ball of the great toe.
Relations. In the first part of its course from the inner ankle to the base of
the fifth metatarsal bone, the artery is covered successively by the abductor hallucis
and the flexor brevis digitorum, by which it is separated from the plantar fascia,
and may be slightly overlapped in muscular subjects by the abductor minimi digiti.
As it approaches the base of the fifth metatarsal bone, it lies, as it turns forwards
630
THE ARTERIES
and inwards before sinking into the foot, in the interspace between the flexor brevis
digitorum and the abductor minimi digiti, and is here only covered by the skin and
superficial fascia, and the plantar fascia. It lies upon the calcaneum, the flexor
accessorius, and the flexor brevis minimi digiti. It is accompanied by the external
plantar nerve, the smaller of the two divisions into which the posterior tibial nerve
divides. In this part of its course it gives off small branches to the contiguous
muscles and to the heel.
In the second part of its course the artery, which is here known as the
plantar arch, sinks into the sole, and is covered, in addition to the skin, superficial
fascia, plantar fascia, and flexor brevis digitorum, by the tendon of the flexor
longus digitorum, the lumbricales, branches of the internal plantar nerve, and the
adductor hallucis. It lies upon the proximal ends of the second, third, and fourth
metatarsal bones and the corresponding interosseous muscles.
The branches of the external plantar artery are:-(1) Muscular; (2) calcaneal;
(3) cutaneous; (4) anastomotic; (5) articular; (6) posterior perforating; and (7)
digital.
(1) The muscular branches of the external plantar are distributed to the
contiguous muscles; in the first part of its course to the flexor brevis digitorum,
and the accessorius; as it makes its bend into the sole, to the muscles of the little
toe; and, as it forms the plantar arch, to the interossei, flexor brevis hallucis, and
adductor hallucis.
(2) The calcanean are two or three small branches which are distributed over the
inner surface of the calcaneum, and anastomose with the internal calcanean branch
of the posterior tibial artery (fig. 379).
(3) The cutaneous pass between the abductor minimi digiti and flexor brevis
digitorum, and through the interval between the middle and outer portions of the
plantar fascia, to the skin.
(4) The anastomotic turn over the outer border of the foot, and anastomose
with the tarsal and metatarsal branches of the dorsalis pedis (fig. 381).
(5) The articular come off from the concavity of the arch, and, running back-
wards and upwards, are distributed to the articulations of the tarsus. They are
homologous to the recurrent branches of the deep palmar arch in the hand, and,
like the latter, are usually three in number.
(6) The posterior perforating, also three in number, ascend through the proximal
end of the second, third, and fourth spaces, between the two heads of origin of
the correspondingly named dorsal interosseous muscles, and communicate with the
proximal ends of the first, second, and third interosseous arteries (fig. 381).
(7) The digital or plantar digital arteries are usually four in number, and are
distributed to the inner and outer sides of the third, fourth, and fifth toes, and to
the outer side of the second toe. They are named first, second, third, and fourth
as they come off from the arch from without inwards, and not according to the
interosseous space in which they run. The first comes off from the outermost part
of the plantar arch, and courses forwards along the outer side of the little toe
(figs. 378, 379, 381), over the fifth metatarsal bone and the abductor and flexor
brevis minimi digiti muscles. The second, third, and fourth digitals run forward
in the centre of the interosseous spaces on the therein contained interosseous
muscles, under cover of the contiguous lumbrical, the short and long flexor
tendons, and the transversalis pedis muscle. Near the cleft of the toes they
become superficial, and bifurcate for the supply of the contiguous sides of the
toes: the second supplying the inner side of the fifth and the outer side of the
fourth toe; the third the inner side of the fourth and the outer side of the third
toe; and the fourth the inner side of the third and the outer side of the second
toe. The supply of the inner side of the second and both sides of the great toe is
derived from the dorsalis pedis through its communicating branch to the plantar

EXTERNAL AND INTERNAL PLANTAR
631
arch. The digital arteries, immediately before they bifurcate, send upwards on to
the dorsum of the foot a communicating branch (the anterior perforating artery)
to the corresponding dorsal interosseous arteries. On the side of the toes the
digital arteries here sometimes called the collateral digital arteries-furnish
numerous small branches to the integuments and the flexor tendons and their
sheaths. They anastomose by many small twigs with the dorsal interosseous
arteries, which also run along the sides of the toes, but more towards the dorsal
aspect. Immediately above each phalangeal joint the collateral digital vessels
communicate by cross branches, forming a rete for the supply of the articular end
zedonand zalugama odT (1)
Ins
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Internal calcanean
branch of posterior tibial
Posterior tibial artery.
Abductor hallucis, cut-
FIG. 379.-PLANTAR ARTERIES (DEEP).
(From a dissection in the Hunterian Museum.)
Internal plantar artery.
Inner head of flexor-
accessorius
Flexor longus hallucis.
External plantar artery
Adductor hallucis
Flexor brevis hallucis
Princeps hallucis artery
Flexor tendons,
cut short
Collateral digital branch
of princeps hallucis to
inner side of great toe
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Cutaneous and
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Outer head of flexor
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Abnormal muscular slip
-Muscular branch
Cutaneous branch
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- Collateral digital artery
to outer side of little toe
Second digital artery
Third digital artery
Fourth digital artery
to Fridi albhin ed
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of the phalanges and the contiguous joints. At the distal end of the toes they also
freely anastomose with each other, forming a rete beneath the pulp and around the
matrix of the nail. The digital arteries are each accompanied by two small veins.
THE INTERNAL PLANTAR ARTERY
adi
The internal plantar artery (figs. 378, 379)-the smaller of the two divisions into
which the posterior tibial divides at the inner ankle-passes forwards along the inner
side of the sole of the foot usually to the first interosseous space, where it ends by
632
THE ARTERIES
anastomosing either with the fifth plantar digital artery (princeps hallucis) derived
from the communicating branch of the dorsalis pedis, or with the branch given off
by the fifth plantar digital to the inner side of the great toe (figs. 378, 379).
Relations. The artery is at first under cover of the abductor hallucis, but
afterwards lies in the interval between that muscle and the flexor brevis digitorum.
It is covered by the skin and superficial fascia, but not by the plantar fascia, since
it lies between the middle and inner portions of that structure.
The branches of the internal plantar are small and irregular in their origin,
course, and distribution. The following are described :-
(1) The muscular branches supply the abductor hallucis, and flexor brevis
digitorum.
(2) The cutaneous branches supply the skin over the course of the vessel.
(3) The articular sink deeply into the sole, and supply the articulations on the
inner side of the foot, and anastomose with branches of the external plantar artery.
(4) The anastomotic run beneath the abductor hallucis and round the inner side
of the foot, to anastomose with the internal tarsal branch of the dorsalis pedis.
(5) The superficial digital are very small twigs which accompany the digital
branches of the internal plantar nerves, and anastomose with the plantar digital
arteries in the first, second, and third spaces. At times a twig from one of these
branches joins the external plantar artery to form a superficial plantar arch.

THE ANTERIOR TIBIAL ARTERY
The anterior tibial artery (fig. 380)-the smaller of the two branches into which
the popliteal artery divides at the lower border of the popliteus muscle-at first
courses forwards between the two heads of origin of the tibialis posticus, and, after
passing between the tibia and fibula through an aperture in the upper part of the
interosseous membrane, runs downwards on the front and outer aspect of the leg,
between the anterior muscles, as far as the front of the ankle joint (fig. 380). Below
this spot it is known as the dorsalis pedis. The course of the vessel is indicated
by a line drawn from the front of the head of the fibula to a point midway between
the two malleoli.
The artery is accompanied by two veins which communicate with each other at
frequent intervals across it. It is also accompanied in the lower three-fourths of
its course by the anterior tibial nerve. The nerve, which winds round the head of
the fibula, and pierces the extensor longus digitorum, first comes into contact with
the outer side of the artery somewhere about the upper third of the leg; then, in
the middle third of the leg, it gets a little in front of the artery, and in the lower
third again lies to its outer side.
Relations. The artery at first lies in the triangle formed by the two heads of
the tibialis posticus and the popliteus muscle; and, as it passes through the hole in
the interosseous membrane, it has the tibia on one side and the fibula on the other.
Posteriorly in its course down the leg it lies in its upper two-thirds upon the
interosseous membrane, to which it is closely bound by fibrous bands; and in its
lower third upon the front of the tibia and the ankle joint.
To its inner side along its upper two-thirds is the tibialis anticus muscle; but at
the lower third it is crossed by the tendon of the extensor proprius hallucis, and then
for the rest of its course has this tendon overlapping it or to its inner side.
On its outer side it is in contact in its upper third with the extensor longus
digitorum muscle; in its middle third with the extensor proprius hallucis; but, as
this muscle crosses to the inner side of the artery, the vessel usually for a very short
part of its course comes again into contact with the extensor longus digitorum.
In front the artery is covered by the skin, superficial and deep fascia. In its


ANTERIOR TIBIAL
633
upper two-thirds it is deeply placed in the cellular interval between the tibialis
anticus on the inner side, and the extensor longus digitorum and extensor proprius
FIG. 380.-THE ANTERIOR TIBIAL ARTERY, DORSAL ARTERY OF THE FOOT, AND
ANTERIOR PERONEAL ARTERY, AND THEIR BRANCHES.
Superior internal articular artery
Inferior internal articular artery
Anterior tibial recurrent artery
Superior external articular artery
Inferior external articular artery
-Extensor longus digitorum
Anterior tibial artery
Tibialis anticus muscle
ANTERIOR TIBIAL NERVE
Extensor longus hallucis
Extensor longus digitorum,
turned back
Peroneus tertius
Anterior peroneal artery
Internal malleolar artery
External malleolar artery
Anterior annular ligament
Peroneus brevis muscle
Dorsalis pedis artery
Extensor brevis digitorum
Communicating branch
Dorsalis hallucis artery
Extensor brevis digitorum
cut
External tarsal branch
Metatarsal branch
Dorsal interosseous artery
hallucis on its outer side: and in its lower third it is crossed from without inwards
by the tendon of the extensor proprius hallucis, and lies beneath the anterior
634
THE ARTERIES
annular ligament of the ankle joint. The anterior tibial nerve is usually in front
of the artery in the middle third of the leg.
The branches of the anterior tibial artery are:-(1) The posterior tibial
recurrent; (2) the anterior tibial recurrent; (3) the muscular; (4) the internal
malleolar; and (5) the external malleolar.
(1) The posterior tibial recurrent is occasionally absent. It ascends between
the popliteus muscle and the posterior ligament of the knee joint supplying these
structures and the superior tibio-fibular joint. It anastomoses with the inferior
external articular branch of the popliteal, and to a less extent with the inferior
internal articular branch.
(2) The anterior tibial recurrent is given off from the anterior tibial artery
immediately after that vessel has passed through the interosseous membrane. It
winds tortuously through the substance of the tibialis anticus muscle, over the outer
tuberosity of the tibia close to the bone; and, perforating the deep fascia, ramifies
on the lower and outer part of the capsule of the knee joint. It anastomoses with
the inferior and superior external articular branches of the popliteal, with the
descending branch of the external circumflex, and somewhat less freely with the
internal articular branches of the popliteal and with the anastomotica magna. It
gives off small branches to the tibialis anticus, the flexor longus digitorum, the
knee joint, and the contiguous fascia and skin. It forms one of the collateral
channels by which the blood is carried to the limb below in obstruction of the
popliteal artery (fig. 376).
(3) The muscular branches, some ten or twelve in number, arise irregularly from
either side of the artery as it courses down the limb, and supply the contiguous
muscles.
(4) The internal malleolar, the smaller of the two malleolar branches, arises from
the lower part of the anterior tibial artery a little higher than the external, usually
about the spot where the tendon of the extensor longus hallucis crosses the anterior
tibial artery. It winds inwards over, the internal malleolus, passing beneath the
tibialis anticus, and forms an internal malleolar plexus or rete about the inner
ankle over the lower end of the tibia by anastomosing with branches from the
posterior tibial, internal plantar, and internal calcanean arteries.
(5) The external malleolar, larger than the internal, arises from the outer side
of the anterior tibial artery, usually on a lower level than the internal malleolar.
It winds in an outward and downward direction round the external malleolus,
passing beneath the extensor longus digitorum and peroneus tertius, and forms the
external malleolar plexus or rete by anastomosing with the anterior peroneal, the
termination of the peroneal, the external plantar, and the external tarsal branch of
the dorsalis pedis (fig. 381).
The anastomosis between the external malleolar and anterior peroneal is some-
times of considerable size, supplying the blood to the dorsal artery of the foot; the
anterior tibial, then much reduced in size, usually ends at the spot where the external
malleolar is usually given off.
THE DORSALIS PEDIS ARTERY
The dorsalis pedis artery is a continuation of the anterior tibial. It extends
from the front of the ankle joint to the proximal end of the first interosseous space
where it dips into the sole to join the external plantar artery and complete the
plantar arch. The course of the artery is indicated by a line drawn from a
point midway between the two malleoli to the proximal end of the first metatarsal
space.
Relations.-Behind, the artery from above downwards lies successively on the
astragalus, scaphoid, and internal cuneiform bones, and the ligaments uniting the


FIG. 381.-DIAGRAM OF THE DISTRIBUTION AND ANASTOMOSES OF THE
ARTERIES OF THE FOOT.
Peroneal artery
Anterior peroneal branch
External malleolar branch
Anterior tibial artery
Internal malleolar branch
Posterior peroneal artery
Malleolar branch of
posterior tibial artery
Communicating branch
between posterior tibial
and peroneal arteries
Dorsalis pedis artery
External plantar artery
Internal plantar artery
External tarsal branch
Internal tarsal branch
External plantar artery
forming plantar arch
Posterior perforating
branches
First digital artery to-
outer side of little toe
Second, third, and
fourth dorsal inter-
osseous arteries given
off from metatarsal
artery
Second, third, and.
fourth digital
arteries
Communicating artery
Dorsalis hallucis or
first dorsal inter-
osseous
Princeps hallucis or
fifth plantar digital
artery
Anterior perforating<
branches
Branch
of third
dorsal interosseous
artery to outer side
of little toe
Dorsal digital
branch of dorsalis
hallucis to inner
side of great toe
gods
636
THE ARTERIES
first and second metatarsal bones. As it sinks into the sole, under the name of
the communicating artery, it lies between the two heads of origin of the first dorsal
interosseous muscle. At times it takes a course a little more outwards, then lying
either partly on the middle cuneiform bone, or on the dorsal ligaments uniting the
middle cuneiform to the internal cuneiform. It is more or less bound down to the
bones by aponeurotic fibres derived from the deep fascia.
In front, the artery is covered by the anterior annular ligament, sometimes by
the extensor longus hallucis, by the skin, the superficial and deep fascia, and, just
before it sinks into the sole, by the innermost tendon of the extensor brevis
digitorum. The angle formed by this tendon with the extensor longus hallucis is
the best guide to finding the artery in the process of ligature (fig. 380).
To its outer side is the innermost tendon of the extensor longus digitorum, and
lower down the innermost tendon of the extensor brevis digitorum. The anterior
tibial nerve is also to its outer side, as is also the outermost of its venæ comites.
To its inner side is the extensor longus hallucis, except at times for about half
an inch below, where the innermost tendon of the extensor brevis digitorum, having
crossed the artery, may lie between it and this tendon. The innermost of the venæ
comites is also to the inner side. Branches between the venæ comites at intervals
cross the vessel.
The branches of the dorsalis pedis artery are:-(1) The tarsal; (2) the meta-
tarsal; (3) the dorsalis hallucis; and (4) the communicating, or plantar digital.
(1) The tarsal branches may be divided into (a) the external, and (b) the
internal. (a) The internal tarsal consists of a few small branches which run over
the inner side of the foot, supplying the skin and articulations, and anastomose
with the internal malleolar. (b) The external tarsal runs outwards over the
scaphoid and cuboid bones, beneath the extensor brevis digitorum. It supplies
branches to that muscle, and to the bones and the articulations between them, and
anastomoses above with the external malleolar and anterior peroneal, below with
the metatarsal, and externally over the outer border of the foot with the anastomotic
branches of the external plantar artery.
(2) The metatarsal artery (figs. 380, 381) runs outwards across the foot, in a slight
curve with the convexity forwards, over the heads of the metatarsal bones, and beneath
the extensor tendons and the extensor brevis digitorum. At the outer border of the
foot it anastomoses, above with the external tarsal, and externally with the anasto-
motic branches of the external plantar. From the convexity of the arch it gives
off three dorsal interosseous arteries, which run forwards on the dorsal interosseous
muscles in the centre of the second, third, and fourth interosseous spaces to the
cleft of the toes, where they bifurcate for the supply of the contiguous sides of the
second and third toes, the third and fourth toes, and the fourth and fifth toes. The
outermost of the interosseous branches gives off a small vessel for the supply of the
outer side of the little toe. At the proximal end of the second, third, and fourth
interosseous spaces each artery receives a branch of communication from the external
plantar artery (posterior perforating), and immediately before they bifurcate a
second communicating artery through the distal end of the interosseous space
the corresponding digital vessel (anterior perforating artery).


from
The little dorsal digital vessels, into which the dorsal interosseous arteries divide
at the cleft of the toes, run along the side of each toe towards the dorsal aspect,
anastomosing with each other across the dorsum of the toes and by frequent
branches with the collateral digital branches of the digital arteries, which also run
along the side of the toes, but nearer the plantar surface. At the end of the toes
they anastomose with each other around the quick of the nail.
(3) The dorsalis hallucis-or first dorsal interosseous artery, as it is sometimes
called-is the apparent continuation of the dorsalis pedis. Like the other dorsal
interossei, it passes forward, in the centre of the first interosseous space, on the first

DORSALIS PEDIS
637
dorsal interosseous muscle. At the cleft of the toes it divides into two dorsal
digital branches--the one for the supply of the outer side of the great toe, the other
for the inner side of the second toe. Before its bifurcation the dorsalis hallucis
gives off a small branch, which runs inwards, under the extensor longus hallucis,
for the supply of the inner side of the great toe; but this branch is sometimes
absent. At the front of the space, immediately before its bifurcation, the dorsalis
hallucis communicates with the fifth plantar digital artery, or princeps hallucis,
through an anterior perforating artery (fig. 381).
(4) The communicating-first interosseous perforating, or plantar digital artery,
as it is variously called-comes off from the dorsalis pedis with the dorsalis hallucis
(into which arteries indeed the dorsalis pedis may be said to divide). At the back
of the first interosseous space it dips into the sole between the two heads of the
first dorsal interosseous muscle, and communicates with the termination of the
external plantar artery, completing the plantar arch, in a manner similar to that in
which the radial artery, passing through the first dorsal interosseous muscle in the
hand, completes by inosculating with the ulnar the deep palmar arch. At the spot
where it joins the external plantar it gives off the fifth plantar digital artery, or
princeps hallucis, which runs forwards in the centre of the first interosseous space to
the cleft between the first and second toe, where it divides into collateral branches
for the adjacent side of each. Before bifurcating, it supplies a branch to the inner
side of the great toe, and receives the anterior communicating artery from the
dorsalis hallucis.


XMOV

THE VEINS
THE
HE veins, like the arteries, are divided into the pulmonary and the sys-
temic.
The pulmonary return the aërated blood from the lungs to the left side of the
heart, and are the only veins that contain arterial blood. The systemic veins bring
back to the right side of the heart the impure venous blood from the rest of the
body. All the systemic veins terminate ultimately either in the superior or inferior
vena cava, except the cardiac veins, which return the blood from the heart's sub-
stance, and open directly into the right auricle.
The veins from the stomach and intestines, the spleen, and the pancreas,
before opening into the inferior vena cava, are collected into a large trunk vein
called the portal vein, which breaks up, like an artery, into capillaries in the
substance of the liver. From these capillaries the blood is again collected by the
hepatic veins, which finally open, as two or more large-sized vessels, into the
inferior vena cava.
The veins are described under the heads of:-1. The veins of the thorax;
2. the veins of the head and neck; 3. the veins of the spine; 4. the veins of the
abdomen; 5. the veins of the upper extremity; and 6. the veins of the lower
extremity.
1. THE VEINS OF THE THORAX
The veins of the thorax are: the pulmonary, which carry the blood from the
lungs to the left side of the heart; and the superior vena cava and its tributaries,
which return the venous blood from the head and neck, the upper extremities, and
the walls of the thorax, to the right side of the heart. The inferior vena cava,
which brings back the blood from the abdomen and pelvis and lower extremities,
is described with the veins of the abdomen, in which cavity it lies throughout by
far the greater part of its course, somewhat less than half an inch of its upper
end only being situated in the thorax.
The pulmonary veins are contained in the middle mediastinum. The superior
vena cava and the right and left innominate veins course through the superior
mediastinum. The azygos veins, the larger of which opens into the superior vena
cava, lie on either side of the thoracic vertebra in the posterior mediastinum. They
receive the intercostal, the bronchial, and the oesophageal veins.

PULMONARY-VENA CAVA SUPERIOR
639
THE PULMONARY VEINS
The pulmonary veins (fig. 320) return the aërated blood from the lungs to the
heart. They are usually four in number, two right and two left. Occasionally,
however, there are three pulmonary veins on the right side, the result of the vein
from the middle lobe of the right lung opening separately into the left auricle instead
of joining as usual the upper of the two right pulmonary veins. The relations of the
pulmonary veins to the pulmonary arteries and bronchi in the lungs are given with
the ANATOMY OF THE LUNGS. At the root of the lung the pulmonary veins on
both sides are arranged as an upper and lower branch, an anterior descending branch
of the bronchus passing between them. The upper vein on the right side is larger
than the lower, and usually receives the vein from the middle lobe of the right
lung. The lower vein on the left side is larger than the upper. Both the upper
and lower veins lie in front of the pulmonary artery and on a lower plane, and run
almost horizontally inwards and forwards to the left auricle. As they pierce the
pericardium they receive a reflexion from the serous layer of that membrane. Their
relations within the pericardium are given with the ANATOMY OF THE HEART.
At the root of the lung their relations to the surrounding structures are similar to
those of the pulmonary artery (page 495). A separate description is not required.
THE VENA CAVA SUPERIOR
The superior or descending vena cava (fig. 381A) carries to the heart the blood
returned from the head and neck and upper extremities through the right and left
innominate veins, and from the walls of the thorax, either directly through the
greater azygos vein, or indirectly through the innominate veins. It is formed
(fig. 381A) by the confluence of the right and left innominate veins at the lower
border of the first right costal cartilage close to the sternum, and, descending
from this spot in a gentle curve with its convexity to the right and in a direction
slightly backwards and outwards behind the sternal end of the first and second
intercostal spaces and second costal cartilage, terminates in the right auricle of
the heart on a level with the third right costal cartilage in front and the seventh
thoracic vertebra behind. It measures about three inches in length (7-8 cm.).
A little more than its lower half (4 cm.) is contained within the pericardium, the
serous layer of that membrane being reflected obliquely over it immediately below
the spot where it is joined by the vena azygos major, and on a lower level than the
reflexion of the pericardium on the aorta. The vena cava superior contains no valve.
Relations. In front (fig. 322), in addition to the first and second intercostal
spaces and the second costal cartilage, it is covered by the remains of the thymus
gland, the interthoracic fascia, and the pericardium, and is overlapped by the right
pleura and lung.
Behind (fig. 324) are the vena azygos major, the right bronchus, the right
pulmonary artery, and the superior right pulmonary vein; and below, the fibrous
layer of the pericardium. The serous layer is reflected over the front and sides
of the vessel, but not over its posterior part.
To the right side are the right lung and pleura, and the phrenic nerve.
To the left side are the right innominate artery and the first or ascending portion
of the arch of the aorta.
Tributaries. In addition to the right and left innominate veins and the vena
azygos major, it receives small veins from the mediastinum and pericardium.

640
THE VEINS
THE INNOMINATE OR BRACHIO-CEPHALIC VEINS
The innominate veins return the blood from the head and neck and upper
extremity. They are. formed on each side by the confluence of the internal jugular
and subclavian veins behind the sternal end of the clavicle. They terminate at the
lower border of the first costal cartilage on the right side by uniting to form the
superior vena cava. The innominate veins have no valves.
The right innominate vein (fig. 382) measures about one to one and a half
inch in length (2-3 cm.), and descends from its origin behind the sternal end of the
clavicle, very slightly forwards and inwards, superficial to, and to the right of, the
subclavian and innominate arteries, to its junction with the left vein behind the
first costal cartilage close to the sternum.
Relations. In front (fig. 327) are the origins of the sterno-hyoid and sterno-
thyroid muscles, the clavicle, the first costal cartilage, and the remains of the
thymus gland.
Behind are the pleura and lung.

To the right are the right pleura and lung, and the phrenic nerve.
To the left (fig. 381A) are the right subclavian artery, the innominate artery,
the right pneumogastric nerve, and the trachea.
The left innominate vein (fig. 381A) measures two and a half to three inches in
length (6-7 cm.), and extends from its origin behind the sternal end of the left
clavicle obliquely across the three main branches of the arch of the aorta to unite
with the right innominate vein at the lower border of the cartilage of the first rib
close to the sternum to form the vena cava superior. In this course it runs from
left to right with an inclination downwards and slightly backwards. A line drawn
obliquely across the upper half of the manubrium of the sternum, from the sterno-
clavicular articulation on the left side to the lower border of the first costal carti-
lage at its junction with the sternum on the right side, will indicate its course.
The left innominate vein is on a level with the top of the sternum at birth.
Relations. In front, in addition to the manubrium of the sternum, it has the
origins of the sterno-hyoid and sterno-thyroid muscles, and the remains of the
thymus gland, the sternal end of the left clavicle, and the sterno-clavicular articu-
lation (figs. 328, 381A).
Behind, are the three chief arteries arising from the arch of the aorta, the
trachea, and the left phrenic and left pneumogastric nerves.
Below it is the transverse portion of the arch of the aorta.
Above it are the cervical fascia and inferior thyroid veins.
Tributaries. In addition to the internal jugular and subclavian veins, by the
confluence of which the innominate veins are formed, each vein receives on its
upper aspect the vertebral, the deep cervical and inferior thyroid veins; and on its
lower aspect the internal mammary vein. The left vein, moreover, is joined by
the left superior intercostal, and by the thymic, mediastinal, and pericardiac veins.
At the confluence of the internal jugular and subclavian veins on the right side,
the right lymphatic duct opens; on the left side the thoracic duct. The vertebral,
the deep cervical, and the inferior thyroid veins are described with the deep veins of
the head and neck (page 666).
The internal mammary veins (fig. 344) are formed by the union of the
venæ comites of the superior epigastric and musculo-phrenic branches of the in-
ternal mammary artery. They receive in their course through the chest collateral
tributaries corresponding to the branches of the internal mammary artery. Just
before reaching the innominate vein they unite behind the first intercostal space
to form a single trunk which opens into the innominate vein on the inner side of
the internal mammary artery. They contain many valves.


INNOMINATE
641
The left superior intercostal vein-or, more correctly speaking, the lower left
superior intercostal vein-longer than the right, which is described as a tributary
of the vena azygos major, receives the intercostal veins from the three or four upper
left intercostal spaces except from the first space, and, ascending over the arch
of the aorta, opens into the left innominate vein. It usually receives the left
FIG. 381A.-THE VENA CAVA SUPERIOR AND THE INNOMINATE VEINS.
(From a dissection in St. Bartholomew's Hospital Museum.)
RIGHT RECURRENT
LARYNGEAL NERVE
Transverse cervical artery
Right common carotid
artery
Suprascapular artery
Internal jugular vein
PNEUMOGASTRIC
NERVE
Subclavian vein
Inferior thyroid vein
PHRENIC NERVE
Left innominate vein
Ascending aorta
Superior vena cava
RIGHT BRONCHUS
Branch to superior
lobe of lung
Upper branch of right
pulmonary artery
Branch to middle lobe:
of lung
Right pulmonary vein
RIGHT AURICLE
Right coronary artery
THORACIC VERTEBRA
Intercostal vein
Intercostal artery
Vena azygos major
Intercostal vein
Intercostal artery
Intercostal vein
Intercostal artery.
THYROID BODY
LEFT RECURRENT
LARYNGEAL
NERVE
PNEUMOGASTRIC
NERVE
Left internal jugular
vein
Left common carotid
artery
Left subclavian artery
Left subclavian vein
TRACHEA
Inferior thyroid vein
PHRENIC NERVE
(hooked aside)
RECURRENT
LARYNGEAL
NERVE
PNEUMOGASTRIC
NERVE
DUCTUS ARTERIOSUS
Left pulmonary
artery
Pulmonary artery
Right pulmonary
artery
LEFT BRONCHUS
Left coronary artery
Left pulmonary vein
RIGHT VENTRICLE
(Conus arteriosus)
CESOPHAGUS
(hooked aside)
THORACIC DUCT
Thoracic aorta
bronchial vein, and communicates with the upper left azygos vein. (See INTER-
COSTAL VEINS, page 644.)
The mediastinal, pericardiac, and thymic veins are small vessels, corresponding
to the arteries of those names given off by the internal mammary. They do not,
however, as a rule, join the internal mammary vein, but unite into a single trunk
(figs. 317, 382), which passes over the transverse part of the arch of the aorta, and
into the lower and anterior part of the left innominate vein.
opens
TT
642
THE VEINS
Chief Variations in the Superior Vena Cava and Innominate Veins
The variations in the vena cava and innominate veins depend upon certain abnormali-
ties in the development of the great veins from the ducts of Cuvier and the primitive
jugular veins, and can here receive only a brief mention. They may be classified as
follows:-
(1) Variations due to the Persistence of the Left Duct of Cuvier
(a) The left subclavian may join the left internal jugular vein to form a trunk which
is continued almost vertically downwards over the arch of the aorta in front of the root of
the left lung, to open into the coronary sinus of the heart. This variety is known as the
persistent left superior vena cava, and is the normal arrangement of the great anterior
veins in some animals. The rudiments of this vein are found in Man in the so-called
oblique vein of Marshall, which stretches from the coronary sinus through the vestigial
fold of the pericardium, and is often continued as a fine fibrous cord to the superior inter-
costal vein.
When the so-called left superior vena cava is present, the upper left azygos vein (the
remains of the left primitive cardinal vein) may open into it by arching over the root of the
left lung in a way similar to that in which the greater azygos (the right primitive cardinal
vein) opens into the superior vena cava over the root of the right lung. The normal left
innominate vein may be absent, or may be quite small or rudimentary, the result of the
non-development, or only partial development, of a transverse branch (which becomes
the left innominate) when the left part of the sinus venosus and the left duct of Cuvier
are transformed into the coronary sinus, the oblique vein of Marshall, and the upper
portion of the left superior intercostal vein.
(b) A vein may run from the left innominate, or left superior intercostal vein, through
the vestigial fold of the pericardium to the coronary sinus, the left innominate vein being
itself normal. This abnormality is similar in kind, but minor in degree, to the former,
described under (a).:
(2) Variations due to Persistence of the Left and Suppression of the Right Duct of
Cuvier
(a) The right innominate vein may cross the arch of the aorta to join a vertical left
innominate vein, and thus form a left superior vena cava, the normal right superior cava
being absent. The arrangement of the azygos veins under this condition may be reversed,
there being a left vena azygos major opening over the root of the left lung into the left
superior cava, and an upper and lower right azygos vein arranged after the manner of the
normal left azygos veins. This arrangement of the veins may occur independently of any
general transposition of the viscera.
(b) There are many other varieties, depending upon abnormalities in the normal
development of the great veins from the Cuvierian ducts and from the primitive jugular
and cardinal veins; but these cannot be discussed here.

THE AZYGOS VEINS

They collect the blood
right side, and from the
They lie on each side of
The azygos veins (fig. 382) are three in number.
returned from the eleven intercostal spaces on the
seven or eight lower intercostal spaces on the left side.
the front of the bodies of the thoracic vertebræ, and establish a communication
between the superior and inferior vena cava through the ascending lumbar veins.
The vena azygos major begins in the abdomen, where it may be looked upon
as a continuation upwards of the ascending lumbar vein (page 671). It passes
through the aortic opening of the diaphragm, runs up through the posterior
mediastinum on the right side of the front of the bodies of the thoracic vertebræ as
high as the fourth thoracic vertebra; then curves forwards over the root of the right
lung, and opens into the superior vena cava immediately before the latter pierces
the pericardium.
Relations. (1) In the abdomen, the vena azygos major lies to the right of
the aorta and thoracic duct, under cover of the right crus of the diaphragm, upon
the first, sometimes upon the second, lumbar vertebra. At this spot it receives
the right subcostal vein, and is continued below into the ascending lumbar vein;


AZYGOS
643
or, if the lower part of this vein is small, it may appear to begin in one of the
lumbar veins, or in the vena cava, or where the portion of the ascending lumbar
vein which communicates with the renal is enlarged, in the renal vein. Through
this intermediation of the ascending lumbar vein, a communication is established
FIG. 382.-THE SUPERIOR AND INFERIOR VENE CAVE, THE INNOMINATE VEINS,
AND THE AZYGOS VEINS.
Right common carotid.
artery
Right internal jugular
vein
RIGHT LYMPHATIC DUCT
Innominate artery-
Right innominate vein.
Internal mammary vein
Trunk of the pericardiac-
and thymic veins
Vena cava superior-
Vena azygos major
Left common carotid
artery
PNEUMOGASTRIC
NERVE
THORACIC DUCT
Left innominate vein
Left subclavian artery
Left superior
intercostal vein
RECURRENT
LARYNGEAL
NERVE
Vena azygos minor, cross-
ing spine to vena azygos
major
Hepatic veins-
Esophageal arteries
Left upper azygos vein
Vena azygos minor
THORACIC DUCT
Right phrenic artery-
Coeliac axis
Middle suprarenal
artery
Left phrenic artery
dio woled
Right spermatic artery
RECEPTACULUM CHYLI
Superior mesenteric
artery
Left ascending lumbar
vein
Left spermatic vessels
See th
Inferior mesenteric
artery
between the iliac veins and the vena azygos. In obstruction of the inferior vena
cava much of the blood from the lower extremities and abdominal wall is returned
by the vena azygos major and its continuation, the ascending lumbar vein, in the
abdomen, to the vena cava superior. (See ASCENDING LUMBAR VEIN, page 671.)
TT 2
644
THE VEINS
(2) At the aortic opening the vena azygos major lies to the right of the aorta
and thoracic duct, between the crura of the diaphragm.
(3) In the posterior mediastinum, as it courses upwards on the right side of
the bodies of the thoracic vertebræ, the vena azygos major crosses in front of the
lower right intercostal arteries, having on its left side the descending aorta and
thoracic duct, in front the root of the right lung and lower down the pleura, and
on its right side the right pleura and lung.
(4) As it curls over the root of the right lung, the vena azygos major is in
contact with the right bronchus, the pneumogastric nerve passing obliquely
between them (fig. 324).
It usually contains an imperfect pair of valves at the spot where it turns
forwards from the fourth thoracic vertebra to arch over the root of the lung; and
still more imperfect valves are found at varying intervals lower down the vein.
Tributaries. (1) The vena azygos minor; (2) the vena hemiazygos acces-
soria, or one or more of the left intercostal veins; (3) the lower end of the lower
superior intercostal vein of the left side (sometimes); (4) the lower right œsophageal
veins; (5) a few right mediastinal veins; (6) the right bronchial vein; (7) the lower
right superior intercostal vein; (8) the nine lower right intercostal veins; and
(9) the right subcostal vein.
The vena azygos minor-also called the lower left azygos and vena hemiazygos
-begins in the abdomen by communicating, like the vena azygos major, with the
ascending lumbar vein of the left side. Through this vein it communicates with
the lumbar veins, the renal, and the iliac veins, and, according as one or other
portion of the ascending lumbar is enlarged and other portions are diminished in size
or obliterated, so may the vena azygos minor appear to begin in the vena cava inferior
or in a lumbar, the renal, or one of the iliac veins. The vena azygos minor, after
receiving the left subcostal vein, passes through the left crus of the diaphragm,
and courses up the posterior mediastinum to the left of the bodies of the lower
thoracic vertebra as high as the eighth, where it turns obliquely to the right, and,
crossing in front of the spinal column behind the aorta and the oesophagus, opens
into the vena azygos major. In its course it crosses over three or four of the
lower left intercostal arteries, and is covered by the pleura.
Tributaries.-(1) The lower four left intercostal veins; (2) the left subcostal
vein; (3) the lower end of the third azygos vein (sometimes); (4) small left
mediastinal veins; and (5) the lower left œsophageal veins.
The vena azygos tertia (also called the upper left azygos and vena hemiazygos
accessoria) varies considerably in size, position, and arrangement, and is often
absent. It lies in the posterior mediastinum by the left side of the bodies of the
fifth, sixth, and seventh thoracic vertebræ, and is more or less vertical in direction.
It is continued above into the lower left superior intercostal vein, and below either
joins the vena azygos minor, or passes obliquely across the sixth or seventh thoracic
vertebra to join the vena azygos major. The intercostal veins intervening between
it and the vena azygos minor then open directly across the spine into the vena
azygos major. It crosses the corresponding left intercostal arteries, and is covered
by the pleura.
Tributaries.-(1) The fifth, sixth, and sometimes the seventh intercostal veins;
(2) the lower end of the lower left superior intercostal vein; (3) the upper end
of the vena azygos minor (sometimes); and (4) the left bronchial vein.
The intercostal veins. The intercostal veins are eleven in number on each side,
and correspond with the intercostal arteries. The last thoracic vein is here called
the subcostal, and is described separately (page 645). There is one vein to each
intercostal artery, the vein lying above the artery whilst in the intercostal space.
Each vein is joined by a dorsal tributary which runs with the dorsal branch of
the intercostal artery between the transverse process of the vertebræ and the neck

INTERCOSTALS
645
of the rib. The dorsal tributaries return the blood from the muscles of the back,
and receive communicating branches from the dorsal spinal plexus and from the
spinal veins through the intervertebral foramina. The intercostal veins also receive
small tributaries from the bodies of the vertebræ. The termination of the inter-
costal veins is different on the two sides, and is seldom alike in any two consecutive
subjects.
On the right side. The first intercostal vein (the upper right superior inter-
costal vein) ascends with the superior intercostal artery, a branch of the subclavian,
to end either in the vertebral vein just before the latter joins the right innominate
vein, or in the right innominate direct. The second intercostal vein either joins
with the first, and opens with it as a common trunk into the vertebral or innominate
vein, or it joins with the third or with the third and fourth to open into the vena
azygos major as the latter is arching over the root of the right lung. This vein is
known as the lower right superior intercostal vein. The fifth, sixth, seventh,
eighth, ninth, tenth, and eleventh right intercostal veins join the vena azygos major.
The upper of these have well-marked valves where they join the azygos vein. In
the lower veins these valves are imperfect. All the intercostal veins are provided
with valves in their course between the muscles.
On the left side the first intercostal vein also follows the superior intercostal
artery from the subclavian, and ascends to join the left vertebral or left innominate
vein, and is known as the upper left superior intercostal vein. The second inter-
costal vein either joins the first, and opens with it as a common trunk into the left
vertebral or left innominate vein, or joins the third and fourth, as described below,
to form the lower left superior intercostal vein. The third and fourth, and some-
times the second, intercostal veins unite to form a single trunk, the lower left
superior intercostal vein, which passes upwards across the arch of the aorta,
and opens into the left innominate vein. This vein usually communicates at its
lower end with the third azygos vein, but at times crosses the spine, and enters
directly the vena azygos major. A fibrous cord can frequently be traced from
it through the vestigial fold of the pericardium to the oblique vein of Marshall
(page 642). The fifth and sixth, and sometimes the seventh, intercostal veins
either end in the third azygos vein, or, if this is absent, cross the spine, and open
directly into the vena azygos major. The eighth, ninth, tenth, and eleventh, and
sometimes the seventh, intercostal veins join the vena azygos minor.
The subcostal vein, or twelfth thoracic vein, lies beneath the last rib, and accom-
panies the twelfth dorsal or subcostal artery. It receives tributaries corresponding to
the branches of the subcostal artery, and opens on the right side into the vena
azygos major, and on the left side into the vena azygos minor.
The bronchial veins correspond to the bronchial arteries, but do not return the
whole of the blood carried to the lungs by those vessels-that part which is distri-
buted to the smaller bronchial tubes and the alveolæ being brought back by the
pulmonary veins. The bronchial veins issue from the lung substance behind the
structures forming the root of the lung. The right vein generally joins the vena
azygos major just before the latter vein enters the superior vena cava. The left
vein opens into the lower left superior intercostal vein, or into the upper left azygos
vein. The bronchial veins at the root of the lung receive small tributaries from
the bronchial glands, from the trachea, and from the posterior mediastinum.
The œsophageal veins from the thoracic portion of the oesophagus end in part
in the vena azygos major, and in part in the vena azygos minor.


646
THE VEINS
THE VEINS OF THE HEART
The cardiac or coronary veins return the blood from the substance of the
heart. They accompany the corresponding coronary arteries, and terminate for the
most part in a dilated vein known as the coronary sinus. This opens directly into
the right auricle of the heart, between the bicuspid opening and the opening of the
inferior vena cava. Some smaller veins from the heart's substance (venæ minimæ
cordis) open separately and directly into the right auricle at the bottom of some of
the small depressions known as the foramina Thebesii.
The coronary sinus is situated at the back of the heart, in the groove between
the left auricle and left ventricle. It measures about an inch in length. Its
Left carotid artery
Left subclavian artery-
FIG. 383.-THE CORONARY SINUS.
Right carotid artery
-Innominate artery
Aorta
Ductus arteriosus-
Pulmonary artery-
Left pulmonary veins-
LEFT AURICLE-
Left coronary artery.
Left marginal artery.
Oblique vein of Marshall-
Left marginal vein.
PERICARDIUM
Coronary sinus
Posterior cardiac vein
-Vena cava superior
Right pulmonary veins
RIGHT AURICLE
-Vena cava inferior
Right coronary artery
-Posterior interventricular
vein
Posterior interventricular
branch of right coronary
Anterior interventricular
branch of left coronary
opening into the auricle is guarded by the so-called Thebesian or coronary valve.
It receives the following tributaries: (1) The great coronary or cardiac vein, of which
it appears to be the large and dilated end; (2) the posterior cardiac or posterior
interventricular vein; (3) the right auricular vein; and (4) the oblique vein.
(1) The great coronary or cardiac vein is formed by the union of (a) the ante-
rior interventricular vein, which runs upwards from the apex of the heart, in the
groove between the right and left ventricles, in company with the artery of that
name; with (b) the left auricular vein, which returns the blood from the left auricle.
The vein thus formed then runs round the left side of the heart, in the groove
between the left auricle and left ventricle, and terminates in the coronary sinus at
the spot where the latter is joined by the oblique vein. Its entrance into the sinus

CARDIAC
647
is guarded by a double valve. It receives (c) the left marginal vein or veins, and
branches from both ventricles, especially the left.
The left marginal vein runs with the artery of that name over the surface of
the left ventricle, along the left margin of the heart. It receives tributaries from
the left ventricle, and terminates in the great coronary vein.
(2) The posterior cardiac, middle cardiac, or posterior interventricular vein
accompanies the posterior interventricular artery upwards, from the apex of the
heart in the posterior interventricular groove. It ends in the coronary sinus, just
before the termination of the latter in the right auricle. It receives tributaries
from the posterior surface of both ventricles, and is guarded by a valve where it
joins the coronary sinus. Two or three small veins (posterior cardiac, or smaller
posterior cardiac) run upwards from the back of the left ventricle, and open into
the coronary sinus by separate orifices guarded by valves.
FIG. 384.-SCHEME OF THE CORONARY VEINS.
Right pulmonary
veins
Left pulmonary-
veins
Inferior vena
cava
Oblique vein.
Great coronary.
or cardiac vein
Superior vena
cava
LEFT AURICLE
-Anterior
RICHTAURICLE
interventricular
Left marginal.
vein
LEFT VENTRICLE
WRIGHT
VENTRICLE
vein
Preventricular or
anterior cardiac
vein
Right auricular
vein
Coronary sinus
Posterior or
middle cardiac
or posterior in-
terventricular
vein
Right marginal
vern
(3) The right auricular, right coronary, or small coronary vein, runs in the
right auriculo-ventricular groove, and terminates in the coronary sinus just before
the entrance of that sinus into the auricle. It is joined by the right marginal
vein and by the preventricular or smaller anterior cardiac vein or veins.
(4) The oblique vein-the greater part of which is often represented merely by a
delicate fibrous cord-runs across the back part of the left auricle, in the vestigial
fold of the pericardium to the coronary sinus. This vein, with the coronary sinus,
its dilated portion, represents what was the left duct of Cuvier and part of the
sinus venosus in the foetus. As stated at page 642, it is occasionally found pervious,
and may be greatly enlarged, and help to form the so-called left superior vena cava.
There is, as might be gathered from the consideration of its morphology, no valve
where the oblique vein is continued into the coronary sinus.
The right marginal vein-sometimes called the anterior cardiac vein, or vein of
Galen-runs over the right ventricle, along the right margin of the heart, and opens
either into the right auricular vein or separately into the lower part of the right
648
THE VEINS
auricle. Other small veins-the smaller anterior cardiac veins (venæ cordis parvæ,
or preventricular veins)-also track up from the anterior surface of the right
ventricle, and open either into the right marginal vein or separately into the right
auricle.
2. THE VEINS OF THE HEAD AND NECK
The veins of the head and neck may be divided for purposes of description into
the superficial, which return the blood from the external parts of the head and
neck; and into the deep, which return the blood from the deeper structures. The
superficial may be again subdivided, according to the region from which they carry
the blood, into (1) The veins of the scalp and face; and (2) the veins of the neck.
The deep veins into which, moreover, some of the superficial open-may be
subdivided into :-(1) The veins of the diploë; (2) the venous sinuses; (3) the veins
of the brain; (4) the veins of the nasal cavities; (5) the veins of the ear; (6) the
veins of the orbit; (7) the veins of the pharynx and larynx; and (8) the deep veins
of the neck. All the veins, whether superficial or deep, sooner or later terminate in
the internal jugular, the external jugular, the vertebral, or the deep cervical vein-
chiefly the two former; and these veins open directly or indirectly into the
innominate veins at the root of the neck, through which all the blood from the head
and neck ultimately passes on its way to the heart. The external jugular vein is
quite superficial; it is formed by the confluence of the veins corresponding to the
upper branches of the external carotid artery, and, after receiving tributaries from
the superficial parts of the neck and from the shoulder, terminates just above the
clavicle in the subclavian vein. The internal jugular vein is deeply placed by the side
of the common and internal carotid arteries. It begins in the jugular fossa, where
it is continuous with the lateral sinus, and, after receiving tributaries corresponding
to the lower branches of the external carotid artery, terminates at the root of the
neck in the innominate vein. The vertebral vein accompanies the vertebral artery
through the foramina in the transverse processes of the cervical vertebræ. It
begins in the suboccipital triangle by the confluence of small veins from the deep
muscles at the back of the occiput, and, after receiving tributaries from the cervical
spine and deep muscles of the neck, ends in the innominate vein. The deep cervical
receives the occipital vein, courses downwards amongst the deep muscles at the
back of the neck, and ends in the innominate vein.


ง
THE SUPERFICIAL VEINS OF THE HEAD AND NECK
1. THE SUPERFICIAL VEINS OF THE SCALP AND FACE
The blood from the scalp is returned by three main channels-viz. an anterior,
which passes over the forehead and face; a posterior, which descends over the
occipital bone; and a lateral, formed by the confluence of two smaller veins which
descend over the parietal and temporal bones respectively-one in front, and one
behind the ear.
THE ANTERIOR SUPERFICIAL VEIN OF THE SCALP AND FACE
The anterior vein descends near the middle line, over the frontal bone, to
the inner angle of the orbit; continues its course by the side of the nose to the
cheek, which it crosses obliquely, to the anterior edge of the masseter muscle, and

VEINS OF THE SCALP AND FACE
649
thence passes through the digastric triangle to the upper border of the hyoid bone,
where it terminates in the internal jugular vein. In this course it is reinforced
by numerous collateral veins, and gradually increases in size. It has, moreover,
numerous communications with the deep veins.
This long continuous trunk vein is variously named according to the region in
which it lies. Thus, as it descends over the frontal bone it is known as the frontal
vein; as it lies by the side of the nose it is called the angular vein; whilst in the
remainder of its course over the face and neck it is spoken of as the facial vein.
FIG. 385. THE SUPERFICIAL VEINS AND LYMPHATICS OF THE SCALP, FACE, AND NECK.
Frontal vein
Supraorbital vein.
Communication with
ophthalmic vein
Transverse nasal vein-
Angular vein-
Lateral nasal veins
Transverse facial vein-
Superior labial or
coronary vein
Anterior pterygoid or-
deep facial vein
Inferior coronary vein-
Facial vein
Inferior labial vein
Submental vein
Lingual vein
Superior thyroid vein
Middle thyroid vein
Anterior temporal vein
Posterior temporal vein
Deep temporal vein
Parotid lymphatic glands
Common temporal vein
-Internal maxillary vein
Occipital vein
Temporo-maxillary vein
Posterior auricular vein
Occipital lymphatic glands
Sterno-mastoid lymphatic
glands
Communication
between
facial and external
jugular veins
Submaxillary lymphatic
glands
Internal jugular vein
Posterior external
jugular vein
External jugular vein
Superficial cervical chain
of glands
Anterior jugular vein
Communication between.
anterior jugular veins
Transverse cervical vein
Suprascapular vein
Jugulo-cephalic vein
√(1) The frontal vein begins about the level of the coronal suture in a venous
plexus which communicates with the anterior division of the temporal vein. Soon
forming a single trunk, it passes vertically downwards over the frontal bone, a short
distance from the middle line and parallel to its fellow of the opposite side, to the
inner canthus of the eyelids, where it takes the name of the angular vein (fig. 385).
Tributaries.-In its course it receives numerous tributaries from the forehead,
and communicates freely with the vein of the opposite side, across the glabella or
root of the nose, by a transverse branch sometimes called the transverse nasal vein.
650
THE VEINS
Just before its termination it receives the supraorbital vein. The transverse nasal
vein usually receives the dorsal veins of the nose.
The supraorbital vein begins over the frontal eminences by intercommunications
with the anterior branch of the superficial temporal vein. It receives tributaries
from the forehead and eyebrow, and, running obliquely downwards and inwards,
opens into the termination of the frontal vein. It communicates with the ophthalmic
vein, and receives the frontal vein of the diploë as the latter vein issues from the
bone at the bottom of the supraorbital notch.
(2) The angular vein, the continuation of the frontal vein downwards, extends
from the junction of the frontal and supraorbital veins a little below the level of
the eyebrow, to the level of the lower margin of the orbit, where it becomes the
facial vein. In this short course it skirts round the inner margin of the orbit,
lying with the angular artery on the nasal process of the superior maxillary bone
a little internal to the lachrymal sac. Branches pass from the posterior part of the
angular vein into the orbit to join the ophthalmic.
The angular, the facial, and the ophthalmic veins contain no valves. The blood,
therefore, can pass either forward from the ophthalmic into the angular, or backwards
through the facial and angular into the ophthalmic, and so on to the cavernous and
other venous sinuses of the cranium. Hence in certain tumours in the orbit and
cranium, the congestion of the angular and facial veins; and the danger in facial
carbuncle and anthrax of septic thrombi spreading backwards through the angular
and ophthalmic veins to the cranial sinuses.
Tributaries. (a) The superior lateral nasal; and (b) the palpebral veins.
(a) The superior lateral nasal veins ascend from the ala and the side of the
nose to join the inner side of the angular vein (fig. 385).
(b) The palpebral veins proceed from the upper and lower eyelids, and open into
the outer side of the angular vein, either separately or by a common trunk. Several
branches of the inferior palpebral vein open into the facial vein (fig. 385).
(3) The facial vein, the continuation of the angular, begins at the lower margin
of the orbit, and, crossing the face obliquely downwards and outwards, passes at
the anterior edge of the masseter muscle over the body of the lower jaw, and thence
downwards and backwards across the digastric and superior carotid triangles to join
the internal jugular vein about the level of the hyoid bone. It runs in a more or
less direct line behind its corresponding artery, the facial, which itself pursues
a tortuous course. It usually passes beneath the zygomatic muscles and beneath
the platysma, but above the other muscles. At the anterior edge of the masseter
it joins the facial artery, lying immediately posterior to it. In the neck it lies
beneath the platysma and cervical fascia, and is usually separated from the facial
artery by the submaxillary gland and the stylo-hyoid, and the posterior belly of
the digastricus muscles, below which it frequently receives a communicating branch
from the external jugular vein. That portion of the vein from the spot where it
receives the communicating branch to its termination in the internal jugular is
sometimes called the common facial vein; and the communicating branch, the
anterior division of the temporo-maxillary vein. (See TEMPORO-MAXILLARY VEIN,
page 653.)
Tributaries. It receives on its inner side, from above downwards :-(a) The
inferior lateral nasal veins; (b) the superior labial vein; (c) the inferior labial veins;
(d) the submental vein; (e) the submaxillary veins. On its outer side :-(a) the
inferior palpebral veins; (b) the anterior internal maxillary vein; (c) the buccal
vein; (d) the anterior parotid vein; (e) the masseteric vein; and (f) the inferior
palatine vein.
Communications.-It communicates with the infraorbital vein, the pterygoid
plexus of veins, the anterior jugular vein, and the external jugular vein.
Tributaries on the Inner Side.-(a) The inferior lateral nasal vein is a small



VEINS OF THE SCALP AND FACE
651
branch which corresponds with the lateralis nasi artery. It joins the facial on a
level with the ala of the nose.
(b) The superior labial or coronary vein begins as a plexus in the orbicularis
oris muscle of the upper lip, and passes with the superior coronary artery outwards,
and joins the facial vein a little below the level of the ala of the nose.
(c) The inferior labial veins.-A small branch (inferior coronary) usually
opens into the facial a little below the superior labial vein; but the chief branch from
the lower lip descends as a rule over the chin to the submental vein, and thus only
opens indirectly into the facial vein. It may open into the anterior jugular vein.
(a) The submental vein lies on the mylo-hyoid muscle superficial to the sub-
mental artery. It begins below the chin, and, running backwards in the digastric
triangle, joins the facial vein just after the latter has passed over the body of
the lower jaw. It receives branches from the inferior labial plexus and the
neighbouring muscles, and communicates with the anterior jugular vein.
(e) The submaxillary or glandular veins open into the facial as it crosses the
submaxillary gland. But some branches from the gland often open into the
submental vein.
Tributaries on the Outer Side.-(a) The inferior palpebral veins.-Several
branches pass downwards to the facial vein; others, as before stated, pass inwards
to the angular vein (page 650). Through one or more of these branches a
communication is formed with the infraorbital vein.
(b) The anterior internal maxillary vein, sometimes known as the deep facial,
passes downwards and forwards from the pterygoid plexus of veins between the
buccinator and masseter muscles, and opens into the outer side of the facial vein
under cover of the zygomaticus major muscle.
(c) The buccal vein is a small branch from the buccinator muscle.
(d) The anterior parotid branch descends downwards and forwards from the
glandula socia parotidis to the facial.
(e) The masseteric is a small branch from the masseter muscle.
(f) The inferior or descending palatine vein accompanies the ascending palatine
or tonsillar artery from the venous plexus about the tonsil and soft palate, and
joins the facial vein just below the body of the lower jaw.
The communicating branch between the external jugular and facial veins-
sometimes known as the anterior division of the temporo-maxillary vein-runs
obliquely downwards and inwards from the external jugular vein from near the spot
where the latter is continuous with the temporo-maxillary trunk. It joins the
facial vein deeply just behind the angle of the jaw.
The chief variations in the facial vein are:-(1) It may run over the sterno-mastoid
and open into the external jugular vein; (2) it may open into the anterior jugular vein;
(3) it may run beneath the posterior belly of the digastricus and stylo-hyoid muscles;
(4) it may receive the lingual vein, the pharyngeal vein, or both of these veins.

THE POSTERIOR SUPERFICIAL VEIN OF THE SCALP
The posterior vein descends over the occipital bone, and then deeply amongst
the muscles at the back of the neck. It ends in the innominate vein. The first
or superficial portion of this trunk is known as the occipital vein; the second or
deeper portion as the deep cervical vein (fig. 385).
The occipital vein begins at the back of the skull in a venous plexus which
anastomoses with the posterior auricular and posterior branch of the superficial
temporal veins. It passes downwards over the occipital bone, and, perforating the
trapezius with the occipital artery, sinks deeply into the suboccipital triangle,
where it terminates in the deep cervical vein. At times it takes a more superficial
course, and, joining the posterior auricular, passes with this into the external
652
THE VEINS
jugular vein. One of its branches-usually the outermost-receives an emissary
vein issuing through the mastoid foramen of the temporal bone, and in this way
forms a communication with the lateral sinus.
The deep cervical vein begins as a plexus of small veins in the suboccipital
triangle. After receiving, as a rule, the occipital vein, it passes downwards between
the complexus and the semispinalis colli, in company, first with the princeps cervicis
branch of the occipital artery, and afterwards with the deep cervical branch of the
superior intercostal artery. On reaching the transverse process of the seventh
cervical vertebra, it turns forward between that process and the neck of the first
rib, and opens either into the innominate vein direct, or into the vertebral
immediately before that vein joins the innominate.
Tributaries. It receives branches from the muscles amongst which it runs.
-
THE LATERAL SUPERFICIAL VEINS OF THE SCALP
The lateral veins descend, one in front and one behind the ear, and unite about
the level of the angle of the jaw to form a single trunk-the external jugular vein.
The anterior vein, the larger of the two, is known as far as the zygoma as the
superficial temporal vein. There it is joined by a deep vein from the temporal
fossa-the middle temporal vein; and the united trunk, now called the common
temporal vein, passes over the zygoma into the parotid gland. Opposite the neck
of the lower jaw it receives the large internal maxillary vein, and takes the name
of the temporo-maxillary vein. This emerges from the lower border of the parotid
gland, and joins the posterior lateral vein, which is known as the posterior auricular,
to form the external jugular vein.
The Anterior Lateral Veins.-The superficial temporal vein returns the blood
from the parietal region of the scalp. It is formed by the union of an anterior and
posterior branch: the former communicates with the supraorbital and frontal veins;
the latter with the posterior auricular and occipital veins and the temporal
vein of the opposite side. These branches lie superficial to the corresponding
branches of the superficial temporal artery, which they roughly though not accurately
follow. Like the artery, they lie between the skin and the cranial aponeurosis, and
descend over the temporal fascia to unite a little above the zygoma, and just in
front of the pinna of the ear, to form the superficial temporal trunk. The vein
thus formed continues its course downwards with the trunk of the temporal artery,
and opposite the zygoma is joined by the middle temporal vein to form the common
temporal vein.
The middle temporal vein corresponds with the middle temporal artery. It
begins in a plexus in the temporal fossa, and then runs backwards between the
layers of the temporal fascia, the outer layer of which it perforates near the
zygoma, to join the superficial temporal vein. It receives an orbital branch, which
corresponds with the orbital branch of the temporal artery and communicates in
front with the ophthalmic vein, the external palpebral veins, and the infraorbital
veins, and then runs backwards between the layers of the temporal fascia to join
the middle temporal trunk or plexus. The middle temporal vein communicates
with the deep temporal veins, and through them with the pterygoid venous plexus.
The common temporal vein, formed by the confluence of the superficial and
middle temporal veins, descends over the zygoma just in front of the pinna of the
ear, lying a little superficial to the temporal artery. Then, passing deeply into
the parotid gland, between the external auditory meatus and the angle of the jaw,
it is joined almost at a right angle by the internal maxillary vein, and becomes the
temporo-maxillary vein.
Tributaries. It receives (a) the transverse facial vein, which corresponds to
the transverse facial artery; (b) articular veins from the plexus around the

VEINS OF THE SCALP
653
temporo-maxillary joint-this plexus receives the tympanic vein, which, together
with its corresponding artery, passes through the fissure of Glaser; (c) parotid
veins, from the substance of the parotid gland; (d) masseteric veins, from the
masseter muscle; and (e) anterior auricular veins, from the pinna of the ear.
The internal maxillary vein accompanies the first part of the internal maxillary
artery between the internal lateral ligament and the neck of the lower jaw. It
begins at the posterior confluence of the veins forming the pterygoid plexus, and
ends by uniting with the common temporal vein to form the temporo-maxillary
trunk.
The pterygoid plexus is formed by the veins which correspond to the branches
of the internal maxillary artery. It is situated, partly on the inner surface of the
internal pterygoid muscle, and partly around the external pterygoid muscle. The
veins entering into this plexus are:-the two middle meningeal, which accom
pany the artery of that name; the posterior dental vein; the mandibular (inferior
dental); the masseteric; the buccal; the pterygoid veins from the pterygoid muscles;
the deep temporal, by which the plexus communicates with the temporal plexus;
the spheno-palatine vein; the supraorbital; the superior palatine; the lower
branch of the ophthalmic vein, which courses through the spheno-maxillary
fissure from the orbit; and the Vesalian vein, through which the plexus communi-
cates with the cavernous sinus. The plexus ends posteriorly in the internal maxillary
vein which joins the common temporal vein, and anteriorly in the anterior internal
maxillary or deep facial vein, which passes forwards and downwards between the
buccinator and masseter muscles to join the facial vein.
The above-mentioned veins, forming by their confluence the pterygoid plexus,
correspond in their course so nearly with that of their companion arteries, that a
detailed description is not necessary. Although deeply placed, they are for
convenience described with the superficial veins.
The temporo-maxillary vein is formed by the union of the common temporal
vein and internal maxillary vein in the substance of the parotid gland. It usually
joins about the angle of the jaw the posterior auricular vein to form the external
jugular. At other times it divides into two branches, an anterior and a posterior.
The anterior division runs forwards and downwards, and joins the facial vein (see
FACIAL VEIN). The posterior division runs backwards over the sterno-mastoid
and joins the posterior auricular to form the external jugular. When the temporo-
maxillary trunk without dividing joins the posterior auricular to form the external
jugular vein, the anterior branch is represented by the communicating branch
between the external jugular and facial veins.
The Posterior Lateral Veins.-The posterior auricular vein begins in a venous
plexus on the posterior part of the parietal bone. This plexus communicates with
the vein of the opposite side, across the sagittal suture, and with the posterior
branch of the superficial temporal vein in front, and with the occipital vein behind.
It descends over the back part of the parietal bone and the mastoid process of the
temporal bone, lying with its artery behind the ear. It then leaves the artery,
and passing over the upper part of the sterno-mastoid muscle obliquely forwards and
downwards, joins the temporo-maxillary vein about the level of the angle of the
lower jaw, forming the external jugular vein (fig. 385).
Tributaries. (a) Auricular veins from the back of the pinna; and (b) the
stylo-mastoid vein, corresponding to the little stylo-mastoid artery. The latter vein.
opens into the posterior auricular vein, as a rule, as the latter leaves the mastoid
process.



654
THE VEINS
2. THE SUPERFICIAL VEINS OF THE NECK
The external jugular vein is formed by the confluence of the posterior auricular
and temporo-maxillary veins near the angle of the lower jaw. It runs obliquely
downwards and backwards across the sterno-mastoid muscle to a spot opposite the
middle of the clavicle, where it terminates as a rule in the subclavian vein. A line
drawn from a point midway between the mastoid process and angle of the jaw to the
middle of the clavicle will indicate its course. It is covered by the skin, superficial
fascia, and platysma, and is crossed by a few branches of the cervical plexus, the
great auricular nerve running parallel to it at the upper part of the neck. It at
first crosses the sterno-mastoid obliquely, then runs nearly parallel to the posterior
border of that muscle, from which it is separated throughout its course by the anterior
layer of the deep cervical fascia.
Just above the clavicle it perforates the cervical fascia, by which it is prevented
from readily collapsing, the fascia being attached to its walls. It then opens into
the subclavian vein; occasionally into the internal jugular, or into the confluence
of the subclavian and internal jugular veins. It contains a pair of valves about one
inch to two inches above the clavicle, and a second pair where it enters the sub-
clavian vein. Both of these valves were shown by Dr. Struthers not to prevent
the blood regurgitating, or injections passing from the larger vein into the external
jugular.
Some anatomists describe the external jugular vein as being formed by the
junction of the posterior auricular and occipital veins. The vein here regarded as the
upper part of the trunk of the external jugular is looked upon by them merely as a
branch of communication between the external jugular and temporo-maxillary vein.
The chief variations of the external jugular vein are :-(1) It may be very small, or much
smaller or much larger than the opposite vein; (2) it may be wanting on one or both sides,
the veins which normally form it then opening into the internal jugular; (3) it may be
formed merely by the posterior auricular vein; (4) it may be perforated by the superficialis
colli nerve; (5) it may receive the facial, the lingual, and the cephalic veins; (6) it may pass
over the clavicle and open into the cephalic or subclavian vein.
Tributaries and communications.-From above downwards, the external jugular
receives a branch from the internal jugular vein; the posterior external jugular,
which in the foetus was part of the primitive jugular vein; a large branch connecting
it with the facial vein; one or two small branches of communication from the
anterior jugular vein; near its termination, the transverse cervical and supra-
scapular veins; and sometimes the anterior jugular vein at the posterior border
and hinder surface of the sterno-mastoid. At times the occipital vein opens into
the external jugular, and is by some anatomists regarded as the normal termination
of the former vein.
The posterior external jugular vein descends from the upper and back part
of the neck, receiving small tributaries from the superficial structures and muscles.
At times it communicates with the occipital, or may appear as a continuation of
that vein. It opens into the external jugular as the latter vein is leaving the sterno-
mastoid muscle. In the foetus this vein returns the blood from the interior of the
cranium through the post-glenoid foramen. Vestiges of the foetal trunk are said to
remain in the mastoid vein.
The suprascapular veins, two in number, correspond to the suprascapular
artery. They usually form one trunk before they open into the external jugular
vein. They contain well-marked valves.
The transverse cervical veins or venæ comites of the transverse cervical artery
-accompany that vessel and open with the suprascapular vein into the external
jugular close to the spot where the latter vein joins the subclavian.

VEINS OF THE HEAD AND NECK
655
The anterior jugular vein begins below the chin by communicating with the
mental, submental, inferior labial, and inferior hyoid veins. It descends a little
external to the middle line, receiving branches from the superficial structures at
the front and side of the neck, and occasionally a branch from the larynx and thyroid
body. Just above the clavicle it turns outwards, and, piercing the fascia, passes
beneath the sterno-mastoid muscle and opens into the external jugular vein just
before the latter joins the subclavian; at times it opens into the subclavian
vein itself. In its course down the neck it communicates with the external
jugular; and, as it turns outwards beneath the sterno-mastoid, sends a branch
across the trachea, between the layers of cervical fascia, to join the anterior jugular
of the opposite side. This communicating vein may be divided in the operation
of tracheotomy, and is then often found greatly engorged with blood. When the
anterior jugular vein is large, the external jugular is small, and vice versa. It is
usually also of large size when the corresponding vein on the opposite side is
absent, as is frequently the case. It contains no valves.
The position of the anterior jugular vein beneath the tendon of the sterno-mastoid
should be borne in mind in tenotomy of that muscle for wry-neck.
THE DEEP VEINS OF THE HEAD AND NECK

The deep veins of the head and neck may be divided into-1. the veins of
the diploë; 2. the venous sinuses of the cranium; 3. the veins of the brain;
4. the veins of the nasal cavities; 5. the veins of the ear; 6. the veins of the
orbit; 7. the veins of the pharynx and larynx; and 8. the deep veins of the neck.
The veins of the diploë terminate partly in the superficial veins already described,
partly in the venous sinuses of the cranium, and partly in the deep veins of the
neck. The venous sinuses open into the deep veins of the neck. The veins of the
brain terminate in the venous sinuses. The veins of the nasal cavities terminate
partly in the deep, and to some extent in the superficial veins. The veins of the
ear join both the superficial and deep veins and the venous sinuses. The veins
of the orbit terminate partly in the superficial veins, but chiefly in the venous
sinuses. The veins of the pharynx and larynx enter the deep veins of the neck.
1. THE VEINS OF THE DIPLOË

The veins of the diploë are contained in bony channels in the cancellous tissue
between the external and internal tables of the skull. They are of comparatively
large size, with very thin and imperfect walls, and form irregular communicating
channels. They have no valves. They can only be seen on removing the external
table of the skull with a file or chisel. They terminate in four or five main and
descending channels, which open, some outwards through the external table of the
skull into some of the superficial and deep veins of the head and face, and some
inwards through the internal table into the venous sinuses. They are divided into
the frontal, fronto-sphenoidal, fronto-parietal or anterior temporal, external parietal
or posterior temporal, and occipital or parieto-occipital.
The frontal are contained in the anterior part of the frontal bone. They con-
verge anteriorly to a single vein which passes downwards, perforates the external
table through a small aperture in the roof of the supraorbital notch, and terminates
in the supraorbital vein.
The fronto-sphenoidal are contained in the lateral parts of the frontal bone, and,
running into the sphenoid bone, terminate in the sinus alæ parvæ.

656
THE VEINS
The fronto-parietal, or anterior temporal, are contained in the posterior part of
the frontal and in the anterior part of the parietal bone. They pass downwards,
and end, partly in the deep temporal veins by perforating the greater ring of the
sphenoid bone, and partly in the superior petrosal sinus.
The external parietal, or posterior temporal, ramifies in the parietal bone, and,
coursing downwards to the posterior inferior angle of that bone, passes either
through a foramen in its inner table, or through the mastoid foramen into the lateral
sinus.
The occipital, or parieto-occipital, ramifies chiefly in the occipital bone, and
opens into the occipital vein or into the lateral sinus.
The diploic veins freely anastomose with one another in the adult; but in the
fœtus, before the bones have united, each system of veins is distinct.
THE LAMBDOID-
SUTURE
The occipital or
parieto-occi-
pital vein
The external
parietal or
posterior tem-
poral vein
THE MASTOID.
FORAMEN
FIG. 386.-THE VEINS OF THE DIPLOË.
(From a specimen in St. Bartholomew's Hospital Museum.)
THE CORONAL
SUTURE
The frontal
diploic vein
The fronto-
sphenoidal vein
The fronto-
parietal or
anterior tem-
poral vein
2. THE VENOUS SINUSES OF THE CRANIUM
The venous sinuses of the cranium are endothelially lined blood-spaces situated
between the periosteal and meningeal layers of the dura mater. They are the
channels by which the blood is conveyed from the cerebral veins, and from some of
the veins of the meninges and diploë, into the veins of the neck. The sinuses of the
base of the skull also carry the chief part of the blood from the orbit and eyeball to
the jugular veins. At certain spots the sinuses communicate with the superficial
veins by small vessels known as the emissary veins, which run through foramina
in the cranial bones.
The venous sinuses are eighteen in number: six being disposed medianly
and singly; six laterally and in pairs. The median and single sinuses are:-
-(1) the
superior longitudinal; (2) the inferior longitudinal; (3) the straight; (4) the
occipital; (5) the circular; and (6) the transverse or basilar. The lateral and
paired sinuses are:--(7) the two lateral; (8) the two superior petrosal; (9) the two
inferior petrosal; (10) the two cavernous; (11) the two spheno-parietal (sinus alæ

VENOUS SINUSES OF THE CRANIUM
657
parvæ), and the two sigmoid-which latter, however, are usually described as part of
the lateral. Occasionally there are two additional sinuses (the two petro-squamous),
due to the persistence in the adult of what in the foetus was the continuation of
the lateral sinus.
(1) The superior longitudinal sinus, or superior sagittal sinus (fig. 388), lies in
the median groove on the inner surface of the calvaria along the attached margin
of the falx cerebri. It extends from the foramen cæcum to the internal occipital
protuberance. It grooves from before backwards the frontal bone, the contiguous
sagittal margin of the parietal bones, and the squamous portion of the occipital
bone. In the foetus it communicates, through the foramen cæcum, with the nasal
veins, and generally throughout life with the superficial temporal vein through the
parietal foramen. It is triangular on section, the base of the triangle corresponding to
FIG. 387.-THE VENOUS SINUSES. ganho digrade
(From a dissection by W. J. Walsham in St. Bartholomew's Hospital Museum.)
Anterior ethmoidal
artery
Posterior ethmoidal
artery
Middle meningeal artery.
OPHTHALMIC
DIVISION OF FIFTH
NERVE
THIRD NERVE
Cavernous sinus.
FOURTH NERVE-
AUDITORY AND
FACIAL NERVES
Inferior petrosal sinus
Petro-squamous sinus
SPINAL ACCESSORY N.
Sigmoid portion of.
lateral sinus
Posterior meningeal
branch of vertebral artery
Left marginal sinus
Circular sinus
Cavernous sinus
SIXTH NERVE
Basilar artery
-Basilar plexus
Auditory artery
Vertebral artery
Anterior spinal artery
HYPOGLOSSAL NERVE
SPINAL ACCESSORY
NERVE
Right marginal sinus
Left lateral sinus
Superior longitudinal-
sinus
Occipital sinus
Right lateral sinus
the bone. Crossing it are a number of fibrous bands known as the chorda Willisii,
and projecting into it in places are the Pacchionian bodies. In front the sinus is
quite small, but it increases greatly in calibre as it runs backwards. It receives at
intervals the superior cortical cerebral veins, and the veins from the falx. The
former, for the most part, open into it in the direction opposite to that in which
the blood is flowing in the sinus. They pass for some distance in the walls of the
sinus before opening into it. Posteriorly, at the internal occipital protuberance, the
superior longitudinal sinus usually turns sharply to the right, and ends in the right
lateral sinus; the straight sinus then usually terminates in the left lateral sinus,
and the right and left lateral sinuses communicate with each other across the
occipital protuberance. Occasionally, however, the superior longitudinal sinus ends
UU

658
THE VEINS
in the left lateral sinus, the straight then passing into the right. At other times
the posterior end of the superior longitudinal sinus at the internal occipital protu-
berance becomes slightly dilated, forming what is called the torcular Herophili, or
confluence of the sinuses. When this dilatation exists, the straight sinus usually
opens into it in front, the two lateral sinuses on either side, the superior longitu-.
dinal above, the occipital sinus or sinuses, when two are present, below. The
torcular may communicate through the occipital emissary vein, which, when
present, passes through a minute foramen in the occipital protuberance, with the
occipital vein.
(2) The inferior longitudinal or inferior sagittal sinus (fig. 388) is situated at
the free margin of the falx cerebri. Beginning about the junction of the anterior
with the middle third of the falx, it is continued backwards along the concave or
lower margin of that process to the junction of the falx with the tentorium, where
FIG. 388.-THE VENOUS SINUSES. (Longitudinal section.)
Superior longitudinal-
sinus
Inferior longitudinal-
sinus
Veins of Galen
Straight sinus
Tentorium cerebelli
Lateral sinus
+
Falx cerebri
Falx cerebelli
SEVENTH AND
EIGHTH NERVES
NINTH, TENTH, AND
ELEVENTH NERVES
TWELFTH NERVE
FOURTH NERVE
THIRD NERVE
SECOND NERVE
SECOND CERVICAL NERVE
FIRST CERVI
CAL NERVE
FIFTH NERVE
Ligamentum denticulatum
SIXTH NERVE
it ends in the straight sinus. The sinus is cylindrical in shape and of small size,
and receives some of the inferior frontal veins of the brain, some of the veins from
the median surface of the brain, and some of the veins of the falx.
(3) The straight sinus, or sinus rectus (fig. 388)-also variously called the sinus
tentorii, perpendicularis, and obliquus-lies along the junction of the falx cerebri
with the tentorium cerebelli. It is formed by the union of the great vein of Galen
and the inferior longitudinal sinus. It receives in its course branches from the
tentorium cerebelli and from the upper surface of the cerebellum. It runs down-
wards and backwards to the internal occipital protuberance, where it ends in the
left lateral sinus, at times in the right lateral sinus, or in the torcular Herophili
when that blood-space is present. On section it is triangular in shape, with its
apex upwards.
(4) The occipital sinus (fig. 387) ascends mesially at the attached margin of the

VENOUS SINUSES OF THE CRANIUM
659
falx cerebelli, along the lower half of the squamous portion of the occipital bone from
near the posterior margin of the foramen magnum to the internal occipital protu-
berance. It usually begins in a right and left branch, known as the marginal sinuses.
These proceed from the termination of each lateral sinus, run round the foramen
magnum, where they communicate with the posterior spinal veins, and unite at a
variable distance from the internal occipital protuberance to form the single occipital
sinus. Sometimes they remain separate as far as the occipital protuberance, then
forming two occipital sinuses. One or other of the marginal sinuses may be
much smaller than the other, or be entirely absent. At the point where the
marginal sinuses unite to form the single occipital sinus, there is a communication
with the posterior spinal veins. The occipital sinus ends either in one of the
lateral sinuses, in the straight sinus, or in the torcular Herophili when this is
present. It receives in its course veins from the tentorium cerebelli, and from the
inferior surface of the cerebellum. It communicates through the plexus of veins
which surrounds the hypoglossal nerve in the anterior condyloid foramen with the
vertebral vein and veins of the anterior spinal plexus.
(5) The circular sinus, so called (fig. 387), is a venous plexus encircling the
hypophysis cerebri, and connecting the right and left cavernous sinuses. The more
distinct channels are found, one in front of the sella turcica, one behind, and one
on its floor, and are sometimes called the anterior, posterior, and inferior inter-
cavernous sinuses, the last being also known as the inferior circular sinus of
Winslow.
(6) The transverse or basilar sinus (fig. 387) is a venous plexus in the substance
of the dura mater over the basilar process of the occipital bone. It extends from
the cavernous sinus to the margin of the foramen magnum below. It communi-
cates laterally with the inferior petrosal sinus, and inferiorly with the anterior
spinal veins. Through this sinus passes the sixth nerve. One of the larger of the
irregular venous channels forming the sinus passes transversely from one inferior
petrosal sinus to the other. It is this portion to which the description of the
transverse sinus given by some authors appears to apply. This venous plexus on
the basilar process is serially homologous with the anterior spinal plexus of veins
on the posterior surface of the bodies of the vertebræ.
(7) The lateral sinus (fig. 387) extends from the internal occipital protuberance
to the jugular foramen. In this course it lies in the groove (which has been named
after it) along the squamous portion of the occipital bone, the posterior inferior
angle of the parietal bone, the mastoid portion of the temporal bone, and the
jugular process of the occipital bone. It at first runs horizontally outwards and
forwards between the two layers of the tentorium cerebelli, following the curve of
the groove on the occipital and the posterior inferior angle of the parietal bones.
In this part of its course it is sometimes known as the transverse sinus, or lateral
sinus proper, but on reaching the groove in the mastoid portion of the temporal
bone it leaves the tentorium and curves downwards and inwards and then forwards
over the jugular process of the occipital bone, and ends in the posterior compart-
ment of the jugular fossa in the sinus jugularis or bulb of the internal jugular
vein. The S-shaped part of the sinus which lies on the mastoid portion of the
temporal and jugular portion of the occipital bone is sometimes known as the
sigmoid sinus. The lateral sinus receives the veins from the temporo-sphenoidal
lobe of the cerebrum, some of the superior and inferior cerebellar veins, some of
the veins of the medulla and pons, the occipital and the external parietal veins of
the diploë, and at the spot where it leaves the tentorium the superior petrosal sinus
and, when present, the petro-squamous sinus. It communicates with the occipital
and vertebral veins through the mastoid and posterior condyloid foramina by
means of emissary veins. As the lateral sinus lies between the tentorium it is on
section prismatic in shape. The sigmoid portion is semicylindrical.


UU 2

660
THE VEINS
ন
7
The right lateral sinus is usually the larger and the direct continuation of
the superior longitudinal sinus, and hence conveys the chief part of the blood
from the cortical surface of the brain and vault of the skull. The left lateral
sinus is usually the smaller and the direct continuation of the straight sinus,
and hence returns the chief part of the blood from the central ganglia of the
brain.
The relation of the lateral sinus to the outside of the skull, especially to the
mastoid process of the temporal bone, is of importance with reference to the opera-
tions of trephining the mastoid cells, opening the tympanum, and exposing the
sinus itself, in septic thrombosis, &c. The course of the sinus corresponds to a line
drawn from the external occipital protuberance to the base of the mastoid process,
or to the asterion, and thence over the back of the mastoid process in a curved line
towards its apex.
(8) The superior petrosal sinus (figs. 387, 388) runs at the attached margin of the
tentorium cerebelli, along the upper border of the petrous portion of the temporal
bone. It connects the cavernous with the lateral sinus. Leaving the outer and
back part of the cavernous sinus just below the fourth nerve, it crosses the fifth
nerve, and, after grooving the petrous bone, ends in the lateral sinus as the latter
turns downwards on the mastoid portion of the temporal bone. It receives veins
from the temporo-sphenoidal lobe of the cerebrum, veins from the cerebellum, veins
from the tympanum through the squamo-petrosal fissure, and sometimes the fronto-
parietal veins of the diploë.
(9) The inferior petrosal sinus (figs. 387, 388) runs along the line of the petro-
occipital suture, and connects the cavernous sinus with the commencement of the
internal jugular vein. It is shorter than the superior petrosal, but considerably
wider. As it crosses the anterior compartment of the jugular foramen, it separates
the glosso-pharyngeal from the pneumogastric and spinal accessory nerves. It
receives veins from the inferior surface of the cerebellum, from the medulla and
pons, and from the internal ear. The last issue through the aqueductus vestibuli
and aqueductus cochleæ.
(10) The cavernous sinus (fig. 387) is an irregular shaped venous space situated
between the meningeal and periosteal layers of the dura mater on the side of the
body of the sphenoid bone. It extends from the central end of the sphenoidal
fissure in front to the apex of the petrous bone behind. Its outer wall is the more
distinct, and contains in it, but separated from the blood by the lining membrane
of the sinus, the third and fourth nerves, and the ophthalmic division of the fifth
nerve, the nerves lying in the above-mentioned order from above downwards, and
from within outwards. The inner wall is less distinct, and is formed chiefly by
the internal carotid artery and the sixth nerve, these structures being separated
from the blood by the endothelial lining of the sinus. Above the carotid the inner
wall is practically absent, the blood-space communicating across the middle line
with the opposite sinus in front, behind, and below the pituitary body or hypophysis
cerebri. (See CIRCULAR SINUS.) The cavernous sinus is traversed by numerous
trabeculæ or fibrous bands, so that there is no central space, but rather a number
of endothelially-lined irregular lacunar cavities communicating with each other.
Hence its name cavernous, from its resemblance to cavernous tissue. In front it
receives the ophthalmic vein, with which it is practically continuous, and just above
the third nerve the sinus alæ parvæ. Internally it communicates with the opposite
sinus, and posteriorly it ends in the superior and inferior petrosal sinuses. It also
receives veins from the inferior surface of the frontal lobe of the brain, and some
of the middle cerebral veins. Through the Vesalian vein, which runs in a minute
foramen in the greater wing of the sphenoid bone, the sinus communicates with
the pterygoid plexus of veins; through the venous plexus around the intraosseous
portion of the internal carotid, with the internal jugular vein; and through small

CEREBRAL AND CEREBELLAR
661
veins which leave the cranium by the foramen ovale and foramen lacerum medium,
with the pterygoid and pharyngeal plexuses.
(11) The spheno-parietal sinus, or sinus alæ parvæ, runs in a slight groove on
the under surface of the lesser wing of the sphenoid bone. It originates in one of
the meningeal veins near the apex of the lesser wing, and, running inwards, passes
through the sphenoidal fold of dura mater above the third nerve into the front part
of the cavernous sinus. It generally receives the fronto-sphenoidal veins from
the diploë.
The petro-squamous sinus is occasionally present. It lies in a groove along the
junction of the petrous and squamous portions of the temporal bone. It opens
posteriorly into the lateral sinus at the spot where the latter enters on its sigmoid
course. In front it sometimes, though very rarely, passes through a foramen in the
squamous portion of the temporal bone between the glenoid cavity and the external
auditory meatus into the temporal vein. This sinus is the rudiment of what in
early foetal life, before the development of the internal jugular vein, was the con-
tinuation of the lateral sinus, the blood from the interior of the skull at this period
passing through the above-mentioned foramen into the primitive jugular vein.
3. THE VEINS OF THE BRAIN

The veins of the brain present the following peculiarities:-(a) They do not
accompany the cerebral arteries. (b) Ascending veins do not as in other situations run
with descending arteries, but with ascending arteries, and vice versa. (c) The deep
veins do not freely communicate. (d) The veins have very thin walls, no muscular
coat, and no valves. (e) The veins opening into the longitudinal, and some of
those opening into the lateral sinus pour in their blood in a direction opposite to
the current in the sinuses, so impeding the flow in both vein and sinus. (f) The
flow of blood in the sinuses is further retarded by the trabeculæ stretching across
their lumen, and in the longitudinal sinus by the blood having to ascend, when the
body is erect, through the anterior half of its course.
The veins of the brain may be divided into the cerebral and the cerebellar.
THE CEREBRAL VEINS
The cerebral veins, like the cerebral arteries, may be divided into the cortical
or hemispheral, and the central or ganglionic.
The cortical, hemispheral or superficial veins ramify on the surface of the brain
and return the blood from the cortical substance into the venous sinuses. They lie
for the most part in the sulci between the convolutions, but some pass over the
convolutions from one sulcus to another. They consist of two sets: a superior and
an inferior.
(1) The superior cortical veins, some eight to twelve in number on each side,
are formed by the union of branches from the convex and median surfaces of the
cerebrum. Those from the convex surface pass forwards and inwards towards the
longitudinal fissure, where they are joined by the branches coming from the median
surface. After receiving a sheath from the arachnoid, they enter obliquely into
the superior longitudinal sinus, running for some distance in its walls. These veins
freely communicate with each other, thus differing from the cortical arteries.
They also communicate with the inferior cortical veins. They may be roughly
subdivided into (a) frontal; (b) paracentral; (c) central; and (d) occipital.
(2) The inferior cortical veins ramify on the base of the hemisphere and the
lower part of its outer surface. Those on the inferior surface of the frontal lobe
pass, in part into the inferior longitudinal sinus, and in part into the cavernous
sinus. Those on the temporo-sphenoidal lobe enter in part into the superior


662
THE VEINS
petrosal sinus, and in part into the lateral sinus, passing into the latter from before
backwards. A large vein from the occipital lobe winds over the crus cerebri and
joins the great vein of Galen just before the latter enters the straight sinus.
One of the inferior cortical veins is sometimes called the middle cerebral vein;
another the great anastomosing vein of Trolard; another the posterior anasto-
mosing vein of Labbé. The first ramifies over the under surface of the frontal
and temporo-sphenoidal lobes, and at the anterior and lower part of the fissure of
Sylvius opens into the cavernous sinus. The second establishes a communication
between the superior longitudinal and cavernous sinuses by anastomosing with the
middle cerebral and one of the superior cortical veins. The third passes from the
middle cerebral vein over the temporo-sphenoidal lobe to the lateral sinus.
The central, ganglionic, or deep cerebral veins are collected into two large
venous trunks, the venæ Galeni, which leave the brain at the great transverse
fissure, that is, between the splenium of the corpus callosum and the optic lobes.
At this spot they unite to form a single vein, the vena magna Galeni, which opens
into the anterior end of the straight sinus. The venæ Galeni are formed by the
union of the choroid vein with the vena corporis striati near the foramen of
Monro. From this spot they run backwards parallel to each other between the
layers of the velum interpositum, and terminate in the way above mentioned.
Tributaries of the veins of Galen.-The choroid vein, the vein of the corpus
striatum, the basilar vein, the veins of the optic thalamus, the vein of the choroid
plexus of the third ventricle, and veins from the corpus callosum, the pineal body,
the optic lobes, and posterior horn of the lateral ventricle. The united trunk, or
great vein of Galen, receives veins from the upper surface of the cerebellum, and
one of the posterior inferior cerebral veins.
The choroid vein runs with the choroid plexus. It begins in the inferior cornu
of the lateral ventricle, and ascends on the outer side of the choroid plexus along
the margin of the velum interpositum to the foramen of Monro, where it unites
with the vein of the corpus striatum to form the vein of Galen. It receives tribu-
taries from the hippocampus major, corpus callosum, and fornix.
The vena corporis striati, formed by veins from the corpus striatum and optic
thalamus, runs forwards in the groove between those structures, passing in its course
beneath the tinea semicircularis, and joins the vein of Galen at the foramen of
Monro. Tributaries. It receives, in addition to the veins from the corpus striatum
and optic thalamus, small veins from the fornix, septum lucidum, and anterior cornu
of the lateral ventricle.
The basilar vein, formed by the confluence of the deep Sylvian vein, the
inferior striate veins, and some small anterior cerebral veins, runs backwards over
the crus cerebri, and enters the vein of Galen near the union of that vessel with
the vein of the opposite side. Tributaries.-The deep Sylvian vein from the insula
and surrounding convolutions; the inferior striate veins from the corpus striatum,
which they leave through the anterior perforated space; anterior cerebral veins.
from the front of the corpus collosum; interpeduncular veins from the structures
in the interpeduncular space; ventricular veins from the middle cornu of the lateral
ventricle; and mesencephalic veins from the mid-brain.

THE CEREBELLAR VEINS
The cerebellar veins are divided into the superior and inferior.
The superior ramify on the upper surface of the cerebellum; some of them
run inwards over the superior vermiform process to join the straight sinus and
great vein of Galen; others run outwards to the lateral and superior petrosal
sinuses.
NASAL-AURICULAR-OPHTHALMIC
663
The inferior, larger than the superior, run, some forwards and outwards to the
inferior petrosal and lateral sinuses, and others directly backwards to the occipital
sinuses.
THE VEINS OF THE MEDULLA AND PONS
Bite
The veins from the medulla oblongata and the pons terminate in the inferior
petrosal and lateral sinuses.
4. THE VEINS OF THE NASAL CAVITIES
10
dez
The venous plexuses on the inferior turbinated bone and back of the septum
are described with the NOSE. The veins leaving the nasal cavities follow roughly
the course of their corresponding arteries. Thus the spheno-palatine veins pass
through the spheno-palatine foramen into the pterygoid plexus; the anterior and
posterior ethmoidal veins join the ophthalmic. Small veins accompany branches of
the facial artery through the nasal bones and nasal process of the superior maxillary
bones, and end in the angular and facial veins; and other small veins pass from the
nose anteriorly into the superior labial, and thence to the facial.

5. THE VEINS OF THE EAR
The veins from the external ear and external auditory meatus join the tem-
poral and posterior auricular veins. The veins from the tympanum open into the
superior petrosal sinus and temporo-maxillary vein. The blood from the labyrinth
flows chiefly through the internal auditory veins which lie with the internal auditory
artery in the internal auditory meatus, and enters the inferior petrosal or lateral
sinus. Some of the blood from the labyrinth, however, passes through the
vestibular vein which lies in the aqueductus vestibuli, into the inferior petrosal
sinus, and some through the aqueductus cochleæ, into the commencement of
the internal jugular vein.
6. THE VEINS OF THE ORBIT
The blood from the eyeball and orbit is returned by the ophthalmic vein into
the cavernous sinus. This vein and its tributaries have no valves, and communicate
in front with the frontal, supraorbital, and other veins. Hence under certain
conditions, as from pressure on the cavernous sinus, the blood may flow in the
contrary direction to the normal-i.e. from behind forwards into the frontal and
supraorbital, and thence through the angular vein into the facial. In this way
pressure on the retinal veins is quickly relieved, and little or no distension occurs
in cases of obstruction in the cavernous sinus.
The ophthalmic vein, or common ophthalmic vein, is formed by the confluence
at the back of the orbit of the superior and inferior ophthalmic veins. It is a short
thick trunk, and passes backwards between the two heads of the external rectus
muscle below the sixth nerve, and at the inner part of the sphenoidal fissure leaves
the orbit and enters the front part of the cavernous sinus.
A. The superior ophthalmic vein, larger than the inferior, begins at the inner
canthus of the eyelid by a free communication with the frontal, supraorbital, and
angular veins, and thence runs backwards and outwards with the ophthalmic artery
across the optic nerve to the inner end of the sphenoidal fissure, where it joins the
inferior ophthalmic vein to form the common ophthalmic trunk. In this course it lies
anterior and superficial to the ophthalmic artery.
roky biog

664
THE VEINS
Tributaries. (1) The superior muscular veins; (2) the ciliary veins; (3) the
anterior and posterior ethmoidal veins; (4) the lachrymal vein; and (5) the central
vein of the retina.
(1) The superior muscular branches are derived from the levator palpebræ,
superior rectus, superior oblique, and internal rectus.
(2) The ciliary veins are divided into two sets: an anterior, which emerge from
the eyeball with the anterior ciliary arteries, and open into the muscular veins
returning the blood from the four recti; and a posterior set, which leave the globe
midway between the cornea and entrance of the optic nerve. The latter veins are
four or five in number, the upper ending in the superior, the lower in the inferior
ophthalmic vein (page 890).
(3) The anterior and posterior ethmoidal veins correspond in their course with
the arteries of the same name. They enter the orbit through the anterior and
FIG. 389.-THE VEINS OF THE ORBIT.
Supraorbital artery-
LACHRYMAL GLAND-
Superior rectus.
EYEBALL-
External rectus.
Commencement of superior
ophthalmic vein
Reflected tendon of
superior oblique
Ophthalmic artery
Anterior ethmoidal artery
Lachrymal artery.
Superior rectus, cut.
Inferior ophthalmic vein.
Superior ophthalmic vein-
OPTIC NERVE-
Posterior ethmoidal artery
Ciliary arteries
Levator palpebræ, cut
Ligament of Zinn
Ophthalmic artery
Common ophthalmic vein-
Internal carotid artery
OPTIC COMMISSURE
posterior ethmoidal foramina, and join either the ophthalmic direct, or one or other
of the superior muscular branches.
(4) The lachrymal vein returns the blood from the lachrymal gland, and corre-
sponds in its course to the lachrymal artery.
(5) The central vein of the retina runs with the central artery in the optic nerve.
It joins the superior ophthalmic at the back of the orbit.
B. The inferior ophthalmic vein, smaller than the superior, is formed near the
front of the orbit by the confluence of the inferior muscular with the lower posterior
ciliary veins. It runs backwards below the optic nerve, along the floor of the orbit,
and either joins the superior ophthalmic vein to form the common ophthalmic
trunk, or else opens separately into the cavernous sinus. A large communicating
branch passes downwards through the spheno-maxillary fissure to join the ptery-
goid plexus of veins.
INTERNAL JUGULAR
665
Tributaries. (1) The inferior muscular, which are derived from the inferior
oblique, inferior rectus, and external rectus; and (2) the lower posterior ciliary
veins.
7. THE VEINS OF THE PHARYNX AND LARYNX

The veins of the pharynx are arranged in the form of a plexus, between the
constrictor muscles and the pharyngeal or prevertebral fascia. The plexus
receives branches from the mucous membrane, from the soft palate, the Eustachian
tube, and the anterior recti and longus colli muscles. Above, it communicates with
the pterygoid plexus of veins; below, either with the lower end of the facial vein,
or with the internal jugular vein.
The veins of the larynx end partly in the superior, and partly in the inferior
thyroid veins.
8. THE DEEP VEINS OF THE NECK
The deep veins of the neck are the internal jugular vein, the vertebral vein,
and the deep cervical vein and their respective tributaries.
THE INTERNAL JUGULAR VEIN
Woupille

The internal jugular vein begins at the jugular fossa, and is the continuation
of the lateral sinus. It passes down the neck in company first with the internal
carotid artery, and then with the common carotid artery to a spot a little external
to the sterno-clavicular articulation, where it joins the subclavian to form the
innominate vein. At its commencement in the larger, and posterior and external
part of the jugular foramen, it is somewhat dilated, forming the so-called bulb or
sinus of the internal jugular vein. At first it lies in front of the rectus capitis
lateralis, and behind the internal carotid artery, from which it is separated by the
hypoglossal, glosso-pharyngeal, and pneumogastric nerves, and by the carotid plexus
of the sympathetic. But as it descends it passes gradually to the outer side of that
vessel, and retains this relation as far as the upper border of the thyroid cartilage.
Thence it runs to its termination along the outer side of the common carotid
artery, being contained in the same sheath with it and the pneumogastric nerve,
but separated from these structures by a distinct septum. The vein generally
overlaps the artery in front; hence the importance in tying the carotid of opening
the sheath well to the inner side of that vessel, in order to avoid the vein. About
an inch above its termination it contains a pair of imperfect valves.

-
Tributaries. At the bulb or sinus the internal jugular vein receives the inferior
petrosal sinus; opposite the angle of the jaw veins from the pharyngeal plexus,
and often a communicating branch from the external jugular vein; opposite the
bifurcation of the carotid it is joined by the facial, and a little lower down by the
lingual and the superior thyroid vein, and at the level of the cricoid cartilage by
the middle thyroid vein.
The inferior petrosal sinus is described with the other sinuses of the brain
(page 660); the pharyngeal plexus with the veins of the pharynx (see above);
and the facial vein with the superficial veins of the scalp and face (page 650).
The lingual vein begins near the tip of the tongue, under the name of the
ranine. It lies at first close to the hypoglossal nerve and beneath the mucous
membrane covering the under surface of the tongue. It then passes backwards
across the hyo-glossus, the latter muscle intervening between it and the lingual
artery. After receiving the sublingual vein and the dorsalis linguæ veins which
roughly correspond to their respective arteries, and the two small veins (venæ
comites) which frequently accompany the lingual artery beneath the hyo-glossus,

666
THE VEINS
the united trunk crosses the common carotid artery and opens into the internal
jugular vein. At times these tributaries open separately into the internal jugular
vein or into the facial vein.
The superior thyroid vein emerges from the upper part of the thyroid body, in
which it freely anastomoses with the other thyroid veins, both in the substance of
the organ, and on its surface beneath the capsule. Thence it passes upwards and
outwards into the internal jugular vein, crossing the common carotid artery in its
At times it forms a common trunk with the facial vein. Its tributaries
are the sterno-hyoid, sterno-thyroid and thyro-hyoid veins from the muscles bearing
those names; and the crico-thyroid and superior laryngeal vein, which correspond
with the crico-thyroid and superior laryngeal arteries respectively. These require
no special description.
course.
The middle thyroid vein passes out from the capsule of the thyroid gland near
the lower part of the lateral lobe of that body, crosses the common carotid obliquely
downwards and outwards, and opens into the internal jugular vein a little below the
cricoid cartilage.
THE INFERIOR THYROID VEINS
The inferior thyroid veins descend from the lower part of the thyroid body
obliquely outwards and downwards to the innominate veins. The right vein
crosses the innominate artery just before its bifurcation, and ends in the right
innominate vein a little above the superior vena cava. It receives inferior laryngeal
veins and veins from the trachea, and has valves at its termination in the innomi-
nate. The left vein passes obliquely over the trachea behind the sterno-thyroid
muscle, and opens into the left innominate vein. It also receives laryngeal and
tracheal veins, and is guarded by valves where it opens into the innominate trunk.
The inferior thyroid veins communicate across the trachea by transverse branches.

THE VERTEBRAL VEINS
The vertebral vein (fig. 342) does not accompany the vertebral artery in its
fourth stage, that is, within the skull, but begins as a plexus of small veins in
the suboccipital triangle. It then enters the foramen in the transverse process of
the atlas, and passes with the vertebral artery through the foramina in the transverse
processes of the cervical vertebræ, forming a plexus around the artery. On
leaving the transverse process of the sixth cervical vertebra it crosses in front of
the subclavian artery and opens into the innominate vein. It has one or two
semilunar valves at its entrance into the innominate vein. In the suboccipital
triangle it communicates with the intraspinal, deep cervical, and occipital veins,
and is joined by veins from the recti and oblique muscles and the pericranium.
Tributaries. As it passes down the neck it receives (1) lateral spinal veins,
which issue along with the cervical nerves and lateral spinal arteries from the
spinal canal; (2) branches from the venous plexus about the bodies of the cervical
vertebræ and their transverse processes; (3) branches from the deep cervical muscles;
and (4) branches from the cervical dorsal spinal veins. Just before it terminates in
the innominate it is joined by (5) the deep cervical vein (sometimes); (6) the anterior
vertebral vein; and (7) the upper superior intercostal vein (sometimes).
-
The anterior vertebral vein begins in a plexus in front of the bodies of the
cervical vertebræ, and, running downwards with the ascending cervical artery
between the scalenus anticus and longus colli muscles, opens into the vertebral
vein just before the latter ends in the innominate. It receives tributaries from the
scaleni, longus colli, and rectus capitis anticus muscles.
The deep cervical vein, which is really a part of the posterior superficial vein
of the scalp, is described with that vein (page 652).

SPINAL
667
3. THE SPINAL VEINS
The spinal veins, which form plexuses around and within the spinal canal from
the cranium to the sacrum, may be divided into the extra- and intraspinal veins.
The extraspinal form a plexus both in front of the bodies of the vertebræ (the
anterior spinal plexus), and in the spinal groove between the transverse and
spinous processes-the dorsal plexus, or dorsal spinal plexus as it is often called.
The intraspinal veins, or those within the spinal canal, may be divided into the
meningeal and the medullary. The meningeal form an anterior and posterior spinal
plexus between the dura mater and the walls of the spinal canal, and are generally
known as the meningo-rachidean veins. They receive the veins from the bodies of
FIG. 390.-THE SPINAL VEINS.
Anterior spinal plexus
MAMMILLARY PROCESS.
ACCESSORY
PROCESS
OR TIP OF THE TRUE
TRANSVERSE PROCESS
COSTAL ELEMENT
Posterior transverse branch
COSTO-TRANSVERSE FORAMINA
Vein from cord
Transverse branch
Anterior transverse vein
Lumbar vein
BODY
Dorsal spinal plexus
Branch
perforating
ligamenta
subflava
Posterior longitudinal
spinal vein
Lateral transverse branch
Anterior longitudinal
spinal vein
Veins from body of
vertebra
the vertebræ. The medullary set are situated within the dura mater; they return
the blood from the spinal cord, and are known as the medulli-spinal veins.
-
1. The extraspinal veins. (a) The veins of the anterior spinal plexus ramify
in front of the bodies of the vertebræ. They are of small size and most distinct
in the cervical region (fig. 390). They open into the neighbouring veins.
(b) The veins of the posterior spinal or dorsal spinal plexus are situated around
the spinous processes, the laminæ, and the articular and transverse processes of the
vertebræ, the larger veins of the plexus running horizontally forwards along the
interspinous ligaments. The plexus is formed chiefly by the union of tributaries
proceeding from the integuments of the back and the spinal muscles. Communi-
cations take place between the veins of each vertebral segment by vertical branches
running upwards and downwards to the plexus above and below respectively near
668
THE VEINS
the base of the transverse processes. Branches are also sent between the lamina
of the several vertebræ to the posterior plexus of the intraspinal veins, and also
forwards between the transverse processes of the vertebræ to join the vertebral vein
in the neck, the dorsal branch of the intercostal veins in the thorax, the lumbar
veins in the lumbar region, and the lateral sacral veins in the sacral region.
2. The intraspinal veins are divided into (a) the meningeal; and (b) the
medullary, or medulli-spinal.
(a) The meningeal extra-medullary or meningo-rachidian veins lie in the
fatty tissue between the walls of the vertebral canal and the dura mater or theca
vertebralis. They are arranged in four longitudinal channels, two of which are
anterior and two posterior, united by transverse branches corresponding in number
to the vertebral segments (fig. 390).
The anterior longitudinal spinal veins extend from the foramen magnum to
the coccyx as two tortuous plexiform vessels, one being placed on each side of the
back of the bodies of the vertebræ behind the posterior common ligament. Opposite
the body of each vertebra they communicate by a transverse branch, which passes
between the body of the vertebra and posterior common ligament, an arrangement
which is sometimes spoken of as the spinal venous ladder. Each transverse branch
as it lies under cover of the posterior common ligament receives the veins from the
bodies of the vertebræ (the venæ basis vertebræ). At the spot where each longi-
tudinal vein is joined by the transverse branch, the vessel becomes considerably
dilated. From the longitudinal vein branches run backwards to join the posterior
longitudinal veins, and opposite the intervertebral foramina a transverse branch
runs outwards to join the vertebral vein, the intercostal veins, the lumbar veins, and
the sacral veins, according to the region of the spine in which the vertebra is situated.
Above, the anterior spinal veins communicate with the basilar plexus at the front
of the foramen magnum.
The posterior longitudinal spinal veins, smaller than the anterior longitudinal
veins, likewise extend from the cranium to the coccyx. They lie between the
posterior wall of the spinal canal and the dura mater. Like the anterior, they
communicate by transverse branches, which receive veins through the ligamenta
subflava from the dorsal spinal plexus. They also communicate with the anterior
longitudinal veins by lateral transverse branches.
It will be thus seen (fig. 390) that in the interior of the vertebral canal, opposite
each vertebral segment, there is a venous ring between the bony wall of the canal
and the sheath of the dura mater, the ring being formed in front by the anterior
transverse vein; on each side by the dilated portion of the trunk of the anterior
longitudinal spinal vein, and the lateral transverse branch; and behind, by the
trunk of the posterior longitudinal vein and the posterior transverse branch. This
venous ring receives veins from the body of the vertebra, from the spinal cord,
and from the meninges, and pours its blood, in part through the lateral veins lying
in the intervertebral foramina into the vertebral, intercostal, lumbar, or sacral
veins; and in part through the branch which perforates the ligamenta subflava into
the dorsal spinal plexus. Above, the posterior longitudinal veins communicate at
the back of the foramen magnum with the occipital sinuses. Around the foramen
magnum a distinct venous ring or plexus is formed by the communication
between the occipital and marginal sinuses and the posterior and anterior spinal
veins.
(b) The medullary or medulli-spinal veins, or veins of the spinal cord, are of
small size, and run in the pia mater in a tortuous course along the spinal cord.
They join the venous ring corresponding to each vertebral segment by passing along
the sheath of dura mater reflected round the spinal nerves.



INFERIOR VENA CAVA
669
4. THE VEINS OF THE ABDOMEN AND PELVIS
All the veins of the abdomen and pelvis-with the exception of the superior
epigastric vein and ascending lumbar vein, which open ultimately into the superior
vena cava-enter directly or indirectly into the inferior vena cava. The veins
corresponding to the parietal branches of the abdominal aorta, except the middle
sacral vein, open directly into the inferior vena cava; the middle sacral vein only
indirectly through the left common iliac vein. Of the visceral veins corresponding
to the visceral branches of the abdominal aorta, those which return the blood from
the stomach, intestines, and pancreas (the chylopoetic viscera), and from the spleen,
end in a common trunk (the portal vein). The portal vein enters the liver, and
breaks up in the liver substance into capillaries like an artery, and from these
capillaries arise the hepatic veins which open into the inferior vena cava as that
vessel grooves the under surface of the liver.
Of the other visceral veins, both renals, the right capsular, and the right sper-
matic or ovarian open directly into the inferior vena cava ; whilst the left capsular
and left spermatic or ovarian only join that vessel indirectly through the left
renal.
Two of the superficial veins of the lower part of the anterior abdominal wall,
the superficial epigastric and superficial circumflex iliac, enter the long saphenous
vein; and two of the deep veins from the like situation, the deep epigastric and
deep circumflex iliac, enter the external iliac vein. The blood in these vessels,
however, can flow upwards as well as in the normally downward direction. In
obstruction of the inferior vena cava they become greatly enlarged, and form, with
the superior epigastric vein and with other superficial veins of the thorax with
which they anastomose, one of the chief channels for the return of the blood from
the lower limbs.
The veins of the pelvis, which receive the veins from the perinæum and gluteal
region, join the internal iliac vein.

THE INFERIOR VENA CAVA

The inferior or ascending vena cava (fig. 391) is the large vessel which returns
the blood from the lower extremities and the abdomen and pelvis. It is formed
by the confluence of the right and left common iliac veins opposite the body of the
fifth lumbar vertebra, ascends in front of the lumbar vertebrae to the right of the
abdominal aorta, passes through the caval opening in the diaphragm, and ends
in the lower and back part of the right auricle of the heart on a level with the
lower border of the ninth thoracic vertebra. At its origin it lies behind the right
common iliac artery on a plane posterior to the aorta, but as it ascends it passes
slightly forward and to the right, getting on a plane anterior to the aorta, and
becoming separated from that artery by the right crus of the diaphragm and the
lobulus Spigelii of the liver. Whilst in contact with the liver it lies in a deep
groove on the hinder surface of that organ, the groove being often converted into
a distinct canal by a thin portion of the hepatic substance bridging across the
groove. As it passes through the diaphragm its walls are attached to the tendinous
margins of the caval opening, and are thus held apart when the muscle contracts.
On the thoracic side of the diaphragm it lies for about half an inch within the
pericardium, the serous layer of that membrane being reflected over it.
Relations. In front it is covered by the peritoneum, and crossed by the right
spermatic artery, branches of the aortic plexus of the sympathetic, the transverse

670
THE VEINS
colon, the root of the mesentery, the duodenum, the head of the pancreas, the
portal vein, and the liver. The median group of the lumbar lymphatic glands are
also in front of it below.
Behind, it lies on the lumbar vertebræ, the right lumbar arteries, the right
renal artery, the right semilunar ganglion, and the right crus of the diaphragm.
To the right are the peritoneum and liver.
To the left is the aorta, and higher up the right crus of the diaphragm.
FIG. 391.-THE ABDOMINAL AORTA AND INFERIOR VENA CAVA.
LEFT LOBE OF LIVER
Cystic artery.
HEPATIC DUCT
CYSTIC DUCT
COMMON DUCT.
Portal vein.
Gastro-duodenal br.
Superior pyloric
Hepatic artery.
Right suprarenal vein
Inferior suprarenal
artery
Renal artery.
Renal vein
Inferior vena cava
KIDNEY
Right spermatic vein.
Right spermatic
artery
Quadratus lumborum
muscle
Lumbar artery and.
vein
Ureteric branch of
spermatic artery
ESOPHAGUS
-Left phrenic artery
Right phrenic artery
-Superior suprarenal
Gastric artery
Inferior suprarenal
Splenic artery
-Left phrenic vein
Left suprarenal vein
Superior mesenteric
artery
KIDNEY
Ureteric branch
of renal
Left spermatic vein
URETER
-Left spermatic artery
Inferior mesenteric
artery
-Ureteric branch of
spermatic
Middle sacral vessels
Ureteric branch of
common iliac
Common iliac artery
External iliac artery
-Internal iliac artery
Tributaries. The inferior vena cava receives the following veins :-(1) the
renal veins; (2) the right suprarenal vein; (3) the right spermatic or (4) the
right ovarian vein; (5) the lumbar veins; (6) the inferior phrenic veins; (7) the
hepatic veins; and (8) the right and left common iliac veins.
(1) The renal or emulgent veins return the blood from the kidneys. They are
short but thick trunks, and open into the vena cava nearly at right angles to that
vessel. The vein on the left side, like the kidney, is a little higher than on the
right, and is also longer, in consequence of its having to cross the aorta. The
comparative shortness of the right renal vein should be borne in mind in the
operation of nephrectomy, since, if too much traction is made on the pedicle, not only
the vein, but a portion of the vena cava may be drawn into the ligature, as shown

TRIBUTARIES OF THE INFERIOR VENA CAVA
671
in a specimen in St. Bartholomew's Hospital Museum. Each vein lies in front of
its corresponding artery. The left vein crosses in front of the aorta, just below the
origin of the superior mesenteric artery. It is covered by the third portion of the
duodenum, and receives the left spermatic, or the left ovarian in the female, and
usually the left suprarenal, and sometimes the left phrenic. There are rudiments
of valves in each vein where it joins the vena cava. Those on the right side, how-
ever, are less well marked.
(2) The suprarenal veins.-There is usually only one suprarenal vein on each
side to return the blood brought to the suprarenal body by the three suprarenal
arteries. On the right side the vein opens into the vena cava direct above the
opening of the right renal vein. On the left side, it opens into the left renal.
(3) The spermatic veins return the blood from the testicle. They begin by the
confluence of small branches from the body of the testicle and epididymis, and as
they proceed up the spermatic cord, in front of the spermatic artery and vas
deferens, become dilated and plexiform, constituting the so-called pampiniform
plexus. After passing through the external abdominal ring, the inguinal canal,
and the internal abdominal ring, the plexus merges into two veins, which lie one
on each side of the spermatic artery. Along with the artery the veins pass up
beneath the peritoneum, and on the left side also beneath the sigmoid flexure of
the colon, across the psoas muscle and ureter, to end as a single trunk, on the right
side in the inferior vena cava, and on the left side in the left renal vein. There are
commonly a number of imperfect valves in the spermatic plexus and a perfect pair
at the termination of each spermatic vein. On the left side, however, the terminal
valve may be wanting.
(4) The ovarian veins begin as the pampiniform plexus near the ovary, between
the layers of the broad ligament. This plexus communicates freely with the uterine
plexus of veins, and with the plexus of veins which extends from the hilum of the
ovary into the ovarian ligament (the ovarian bulb). After passing from between
the layers of the broad ligament, the plexus unites to form at first two and then
a single vessel, which accompanies the ovarian artery, following a similar course
to the spermatic veins in the male. The right ovarian vein opens into the
inferior vena cava; the left into the left renal. They usually contain imperfect
valves in their plexiform part, and a perfect valve where they join the vena cava
and renal vein respectively.
(5) The lumbar veins.-There are usually four lumbar veins on each side corre-
sponding to the lumbar arteries. The main trunks of these veins, which lie beside
the bodies of the lumbar vertebræ, are formed by the union beneath the psoas of
anterior and posterior branches. The anterior branches collect the blood from
the front and lateral walls of the abdomen. They communicate in front with the
internal mammary and epigastric veins, and then run backwards between the
abdominal muscles in company with the anterior branches of the lumbar arteries
to their confluence with the posterior branches. The posterior branches collect the
blood from the loins and muscles of the back, and correspond to the posterior or
dorsal division of the lumbar arteries. They receive communicating branches
from the dorsal spinal plexus and from the vertebral canal, and pass forwards
between the transverse processes to join the anterior branches. The trunk lumbar
veins are connected beneath the psoas muscle by vertical branches, which cross in
front of the transverse processes. The last lumbar vein is variously joined below
by a vertical branch to the common iliac, internal iliac, lateral sacral or ilio-lumbar
vein, and the first lumbar vein is similarly connected above with the commence-
ment of the vena azygos major on the right, and the vena azygos minor on the left
side. The vertical vein thus formed is known as the ascending lumbar vein, and
is regarded by some morphologists as the remains of the primitive or cardinal vein
of the embryo. The trunk lumbar veins run up beneath the tendinous arches of



672
COIS THE VEINS O
the psoas on the sides of the bodies of the vertebræ in company with the lumbar
arteries and branches of the sympathetic nerve, and end in the inferior vena cava
on its posterior aspect. The left veins are longer than the right, and pass behind
the aorta.
(6) The phrenic veins, or inferior phrenic veins as they are sometimes called,
follow the course of the phrenic arteries: the right opens into the vena cava direct;
the left into the suprarenal, the left renal, or the vena cava.
(7) The hepatic veins, the largest tributaries of the vena cava, return the blood
from the liver. Commencing in the substance of the liver (see LIVER), they
converge as they approach its posterior surface, and unite to form two or three
large branches, which open into the vena cava as it lies in the groove or canal in
that organ. Some smaller vessels from the lobulus Spigelii, and other parts of the
liver in the neighbourhood of the caval groove, open directly into the vena cava.
The hepatic veins contain no valves, but, in consequence of those from the right
and left lobe of the liver opening obliquely into the vena cava, present a semilunar
fold at the lower margin of their orifices.
Chief Variations in the Inferior Vena Cava
(1) The inferior vena cava, in cases of transposition of the viscera, may lie on the
left side of the aorta. (2) Without transposition it may also lie to the left of the aorta,
crossing to the right to gain the caval opening immediately below the diaphragm,
or after receiving the left renal vein. (3) It may be double, the left cava then usually
passing across the aorta into the right after receiving the left renal vein. A communi-
cation between the right and left veins in the position of the normal left common iliac
vein may or may not then exist. (4) The inferior vena cava may be absent, the blood
from the lower extremities passing by a large vein in the position of the ascending lumbar
and azygos veins through the diaphragm to open into the superior vena cava. The
hepatic veins then open directly into the right auricle through the normal caval opening
in the diaphragm. (5) The inferior vena cava may receive the left spermatic vein. (6)
It may receive a left accessory renal vein passing behind the aorta, and into this the usual
tributaries of the left renal vein may open. (7) It may receive several accessory renal veins;
as many as seven on each side have been met with. (8) The lumbar veins may enter it
on one or both sides as a common trunk.


(8) THE COMMON ILIAC VEINS

The common iliac veins are formed opposite the sacro-iliac synchondrosis by
the confluence of the external iliac and internal iliac veins. They converge as they
ascend, and unite opposite the upper border of the fifth lumbar vertebra to form
the vena cava inferior a little to the right of the median line.
The right vein, shorter and more vertical in direction than the left, passes
obliquely behind the right common iliac artery to its outer side, where it is joined
by the left common iliac vein.
The left vein lies to the inner side of the left common iliac artery, and, after
crossing in front of the promontory of the sacrum and fifth lumbar vertebra below
the bifurcation of the aorta, passes beneath the right common iliac artery to join.
the right vein and form the inferior vena cava. The left vein may contain an
imperfect valve.
Tributaries.-The ilio-lumbar veins may enter the lower part of the common
iliac, or open into the internal iliac vein. The left vein receives the middle sacral
veins.
(a) The ilio-lumbar veins follow the course of the ilio-lumbar artery, and end
either in the common iliac or in the internal iliac vein.
(b) The middle sacral veins ascend on either side of the middle sacral artery in
front of the sacrum, to open usually by a single trunk into the left common iliac



COMMON ILIAC-PORTAL
673
vein. They communicate with the lateral sacral veins, forming the so-called pre-
sacral plexus. Below, the middle sacral veins communicate with the hæmorrhoidal
veins.
Chief Variations in the Common Iliac Veins
(1) Either common iliac vein may be double, or double only for a portion of its extent.
(2) One may be absent,-the external and internal iliac veins joining the opposite common
iliac to form the vena cava. (3) The right and left internal iliac veins may unite and
open as a common trunk at the confluence of the right and left external iliac veins to
form the vena cava. (4) The middle sacral trunk vein may divide, and one branch open
into the right, and the other into the left common iliac vein.
THE PORTAL VEIN AND ITS TRIBUTARIES
The veins corresponding to the inferior mesenteric, the superior mesenteric,
and the branches of the cœliac artery, with the exception of the terminal branches
of the hepatic artery, do not join the inferior vena cava direct, but unite to form a
common trunk-the portal vein.
This vein enters the liver, and breaks up in its substance into capillaries like an
artery, from which the blood is again ultimately collected by the hepatic veins,
and carried by them into the inferior vena cava. The terminal branches of the
hepatic artery also break up in the liver into capillaries, and from them the blood
likewise finds its way finally into the hepatic veins, and thence into the inferior
vena cava. Thus the arterial blood, leaving the aorta for the supply of the stomach,
the intestines, the pancreas (the so-called chylopoetic viscera), and the spleen,
passes, before it reaches the vena cava, through two sets of capillaries: viz. the
capillaries of the viscera and the capillaries of the liver. Hence the portal system
of veins may be said to terminate in capillaries at each end; to begin, like other
veins, in capillaries in the viscera; but, unlike other veins, to end in capillaries like
an artery, instead of in a larger and larger vein till the auricle is reached. The
portal vein and its tributaries have no valves.
The portal vein is a thick trunk about three inches in length (7-8 cm.). It
is formed behind the pancreas, opposite the right side of the body of the second
lumbar vertebra, by the union of the superior mesenteric with the splenic vein.
After passing behind the first part of the duodenum, and then between the layers of
the lesser omentum in company with the hepatic artery and the hepatic duct, it
enters the transverse or portal fissure of the liver, and there divides into a right and
left branch. In this course it passes upwards and to the right, having both the
hepatic artery and the common bile duct in front, the former to the left, the latter
to the right. It is surrounded by branches of the hepatic plexus of the sym-
pathetic nerve, and by numerous lymphatic vessels and some glands. The
connective tissue sheath enclosing these structures is called the capsule of Glisson.
Just before it divides it is somewhat dilated, the dilated portion being called the
sinus of the portal vein. The division into right and left branches takes place
towards the right end of the transverse fissure of the liver. The right branch is
shorter and thicker than the left, and supplies the right lobe of the liver and a
branch to the quadrate lobe. The left branch is longer and smaller than the right,
and supplies the left lobe, and gives a branch to the Spigelian and quadrate lobes.
It is joined, as it crosses the longitudinal fissure, by a fibrous cord, known as the
round ligament of the liver or the obliterated umbilical vein, and posteriorly by a
second fibrous cord, the remains of the ductus venosus. In the foetus the blood
passes through the umbilical vein and ductus venosus directly into the vena cava,
a very small quantity only turning to the right and left into the branches of the
portal vein. Before birth, the blood in that part of the left branch of the portal



X X

674
THE VEINS
vein which lies between the trunk of the vena porta and the umbilical vein travels
from left to right; but after birth, as the portal circulation becomes freely esta-
blished and the umbilical vein and ductus venosus are obliterated, in the opposite
direction, i.e. from right to left.
Tributaries.-The pyloric, the gastric, the cystic (which latter usually enters
the right branch), the superior mesenteric, and the splenic.
The pyloric vein begins near the pylorus in the lesser curve of the stomach,
and, running from left to right with the superior pyloric artery, opens directly into
the lower part of the portal vein. It receives branches from the pancreas and
duodenum.
FIG. 392.-THE VEINS OF THE STOMACH AND PORTAL VEIN.
(From a dissection by W. J. Walsham.)
Cystic vein
Right branch of
portal vein
Portal vein
Hepatic artery-
Continuation of
hepatic artery
Gastro-duodenal-
artery
Pyloric vein
Right gastro-
epiploic vein
Omental veins-
M
E
V
E
ANCREA
M
R
C
U
M
H
Left branch of
portal vein
Veins corre-
sponding to
vasa brevia
arteries
Gastric artery
Hepatic artery
Splenic artery
Gastric or
coronary vein
Left gastro-
epiploic vein
The gastric or coronary vein runs with the gastric artery at first from right to
left, along the lesser curve of the stomach, towards the cardiac end, and then, turning
to the right, passes across the spine from left to right to end in the portal trunk a
little higher than the pyloric vein (fig. 392). At the cardiac end of the stomach it
receives small branches from the oesophagus.
The cystic vein returns the blood from the gall-bladder. It usually opens into
the right branch of the portal vein.
The superior mesenteric vein begins in tributaries which correspond with the
branches of the superior mesenteric artery. It courses upwards a little, in front and
to the right of the artery, passing with that vessel from between the layers of the
XX

PORTAL
675
mesentery in front of the duodenum, and behind the pancreas, where it joins the
splenic vein to form the portal trunk.
Tributaries. In addition to the tributaries corresponding to the branches of
the superior mesenteric artery-viz. the ileo-colic, right colic, middle colic, and small
intestinal veins (fig. 393)-it receives the right gastro-epiploic and the pancreatico-
duodenal veins just before its termination in the portal vein.
The right gastro-epiploic vein accompanies the artery of that name.
from left to right along the greater curvature of the stomach, receiving branches
from the anterior and posterior surfaces of that viscus, and from the great
FIG. 393. THE SUPERIOR MESENTERIC VEIN.
(The colon is turned up, and the small intestines are drawn over to the left side.)
TRANSVERS
LON
Middle colic
artery
Inferior
pancreatico-
duodenal
artery
Right colic
artery
Ileo-colic
artery
CÆCUM
VERMIFORM
APPENDIX
ASCENDING COL
DU
UM
ANCREAS
ESCENDING
COLON
Left colic artery
-Superior mesen-
teric artery
and vein
JEJUNUM
Vasa
intestini tenuis
-SMALL
INTESTINES
omentum, and, passing behind the first portion of the duodenum, ends in the
superior mesenteric vein just before that vessel joins the portal trunk.
The pancreatico-duodenal vein runs with the corresponding arteries between
the head of the pancreas and the second portion of the duodenum, and ends in the
superior mesenteric vein a little below the spot where that vessel is joined by the
right gastro-epiploic vein.
The splenic vein issues as several large branches from the hilum of the spleen.
These soon unite to form a large trunk, which passes across the aorta and spine in
company with the splenic artery, below which it lies, to join at nearly a right angle
the superior mesenteric vein. In this course it lies behind the pancreas; and at its
X X 2

676
THE VEINS
union with the superior mesenteric to form the vena porta, in front of the inferior
vena cava.
Tributaries. It receives veins corresponding to the vasa brevia arteries from
the cardiac end of the stomach, the left gastro-epiploic vein, veins from the
pancreas, and the inferior mesenteric vein.
The left gastro-epiploic vein accompanies the left gastro-epiploic artery. It
runs from right to left along the greater curvature of the stomach, receives branches
from the stomach and omentum, and opens into the commencement of the splenic
vein.
The inferior mesenteric vein begins at the rectum in the superior and middle
hæmorrhoidal veins. It passes out of the pelvis with the inferior mesenteric artery;
FIG. 394.-THE INFERIOR MESENTERIC VEIN.
(The colon is turned up, and the small intestines are drawn to the right side.)
Middle colic.
artery
Inferior pancrea-
tico-duodenal
artery
Superior
mesenteric artery
Right colic artery-
Abdominal aorta-
Vena cava.
inferior
Right common
iliac artery
Middle sacral
artery and vein
TRANSVERSE
COLON
DENUM
PANCREAS
DESCENDING
COLON
-Left colic artery
Inferior
mesenteric vein
Inferior mesen-
teric artery
Left colic artery
Inferior mesen-
teric artery
Left common
iliac vein
Sigmoid artery
SIGMOID
FLEXURE
-Superior 24
hæmorrhoidal
artery
but, after receiving the veins corresponding with the sigmoid and left colic branches
of that vessel, it leaves the artery and runs upwards on the psoas to the left of the
aorta and behind the peritoneum. On approaching the pancreas it turns slightly
inwards, and passes obliquely behind that gland to join the splenic vein just before
the latter unites with the superior mesenteric to form the vena porta.
THE VEINS OF THE PELVIS
The veins of the pelvis, with the exception of the middle sacral vein which
terminates in the left common iliac vein, open into the internal iliac vein. Under
the head of pelvic veins are included all of those corresponding to the branches of

VEINS OF PELVIS
677
the internal iliac artery except the hypogastric branch, although some of these
veins do not return the blood from the pelvic walls or viscera.
The internal iliac vein is formed by the confluence of the veins (except the
umbilical) corresponding to the branches of the internal iliac artery. It varies
considerably in length, but is usually quite a short trunk, extending from the upper
part of the great sacro-sciatic foramen to the sacro-iliac synchondrosis, where it
joins the external iliac to form the common iliac vein. It lies behind and a little
internal to the internal iliac artery. It contains no valve.
Tributaries. The internal iliac vein receives directly or indirectly the following
branches: the gluteal, ilio-lumbar, lateral sacral, obturator, sciatic, pudic, dorsal
penile, prostatic, vesical, and hæmorrhoidal veins. The single umbilical vein-the
vein corresponding to the right and left hypogastric arteries and their continuation,
the umbilical arteries-does not enter the pelvis, but, leaving the umbilical arteries
at the navel, passes along the falciform ligament to the liver. After birth it is
converted into a fibrous cord. (See PORTAL VEIN, page 673.)
The gluteal veins accompany the gluteal artery, and, passing through the upper
part of the great sciatic foramen, open into the internal iliac vein near its termina-
tion, either separately or as a single trunk.
The ilio-lumbar veins open into the internal iliac a little higher than the
gluteal. At times they join the common iliac vein.
The lateral sacral veins join the gluteal or the internal iliac at or about the
same situation as the gluteal. They form with the middle sacral veins a plexus in
front of the sacrum, and receive branches from the sacral canal.
The obturator vein, which lies below the obturator artery as it crosses the side
of the pelvis, opens into the front of the internal iliac vein a little below the gluteal.
Its branches correspond to those of the artery.
The sciatic veins accompany the sciatic artery, and, as a rule, unite to form a
single trunk before joining the internal iliac a little below the obturator vein.
All the above veins so closely follow the ramifications of their respective
arteries, that no further special description of them is required. They all contain
valves.
The pudic vein does not begin as the dorsal vein of the penis, but issues from
the corpus cavernosum with the artery of that body. It communicates, however,
with the dorsal vein before the latter pierces the triangular ligament. In the rest
of its course it runs with the pudic artery, receiving tributaries corresponding
to the branches of that vessel. It terminates in the lower part of the internal
iliac vein.
The dorsal vein of the penis begins in a plexus around the corona glandis,
then runs along the centre of the dorsum of the penis between the two pudic
arteries. In this course it receives large tributaries from the interior of the organ,
which, emerging for the most part between the corpus spongiosum and corpus
cavernosum, wind obliquely over the outer surface of the latter structure to the
dorsum of the penis to end in the dorsal vein. At the root of the penis the dorsal
vein leaves the dorsal arteries, and, passing straight backwards between the two layers
of the suspensory ligament, and then through either the subpubic ligament or the
upper part of the triangular ligament of the pelvis (fig. 371) bifurcates, each branch
passing backwards and downwards to the prostatico-vesical plexus of veins. At
times the dorsal vein begins as two branches, which run between the dorsal arteries
and only unite to form a single trunk about an inch and a half from the triangular
ligament. Before passing through the triangular ligament, it communicates on each
side with the primary radicals of the pudic vein. After dividing into a right and
left branch within the pelvis, each vessel generally communicates with the obturator
vein by a branch passing over the back of the pubes to the obturator foramen.
The prostatico-vesical plexus surrounds the prostate and the neck and lower


678
THE VEINS
fundus of the bladder. It receives in front the right and left divisions of the
dorsal vein of the penis, and communicates posteriorly with the hæmorrhoidal
plexus. The prostatic veins and the vesical plexus open into it. The veins
forming the plexus are of large size, especially in old men, in whom they often
become varicose, and contain phleboliths, or vein-stones. The plexus is surrounded
by a kind of capsule formed by the recto-vesical process of the pelvic fascia. It
terminates in a single stem on each side which opens into the internal iliac vein.
The vesical plexus surrounds the upper fundus, the sides, and the anterior and
posterior surfaces of the bladder. It is situated between the muscular coat and
the peritoneum, and where the bladder is uncovered by peritoneum external to the
muscular coat in the pelvic cellular tissue. It opens into the prostatico-vesical plexus.
The hæmorrhoidal plexus of veins surrounds the rectum, and is situated at the
lower part of that tube between the muscular and mucous coats. The veins of this
plexus terminate in the inferior, middle, and superior hæmorrhoidal veins. The
inferior join the pudic; the middle accompany the middle hæmorrhoidal arteries,
and open into the internal iliac and superior hæmorrhoidal veins; the superior form
the commencement of the inferior mesenteric vein, and through this the blood
gains the portal vein. None of these veins have any valves; hence the enlargement
of the inferior hæmorrhoidal veins, a condition known as piles, when the portal
vein is obstructed, as from compression of its capillaries in cirrhosis of the liver.
Through the hæmorrhoidal veins a free communication is established between the
systemic and portal system of veins.
5. THE VEINS OF THE UPPER EXTREMITY
The veins of the upper limb consist of two sets-a superficial and a deep.
The superficial veins ramify in the subcutaneous tissue above the deep fascia;
the deep accompany the arteries, and have practically the same relations as those
vessels. The superficial and deep veins communicate at frequent intervals
through the intermuscular veins which run between the muscles and perforate the
deep fascia. Both sets of veins are provided with valves, but the valves are more
numerous in the deep than in the superficial. There is usually a valve where the
deep veins join the superficial. The superficial veins are larger than the deep, and
take the greater share in returning the blood.
I. THE SUPERFICIAL VEINS OF THE UPPER EXTREMITY
doga
The superficial veins begin in two irregular venous plexuses: one situated on
the back of the hand, and the other on the front of the wrist. From the radial
side of the dorsal plexus, a single vein, the superficial radial, runs up the forearm
as far as the elbow. From the ulnar side of the plexus, two veins course up the
inner side of the forearm the anterior and posterior superficial ulnar veins and,
joining together a little below the bend of the elbow, form a single superficial ulnar
vein. From the anterior plexus a vein runs up the middle of the front of the
forearm the superficial median vein-and, after receiving a branch from the deep
veins at the bend of the elbow (the deep median), divides into an outer branch (the
median cephalic) and an inner branch (the median basilic). The median cephalic
runs upwards and outwards to join the superficial radial vein. The united trunk,
then known as the cephalic, continues up the outer side of the arm, and opens into
the axillary vein. The median basilic runs upwards and inwards to join the


SUPERFICIAL VEINS OF UPPER EXTREMITY
679
superficial ulnar vein. The trunk thus formed (the basilic) courses up the inner
side of the arm to join the inner brachial vena comes and form the axillary vein.
The dorsal venous plexus, which is situated on the back of the hand, some-
times takes the form of an irregular arch, stretching across from the radial to
the ulnar side; at other times, the form of two more or less distinct plexuses, a
radial dorsal and an ulnar dorsal; but an exactly similar arrangement is seldom
met with in any two consecutive bodies.
The distal part of the arch or plexus receives the digital veins from the fingers.
These digital veins, two to each finger, start from a minute plexus about the nail,
run along the finger, one on either side, to the cleft, where each unites with the
vein from the contiguous side of the neighbouring finger, and so form single trunks
which proceed upwards to the arch. The veins of the fingers communicate at
frequent intervals by cross branches above and below the interphalangeal joints.
Here it may be noted, that whilst the veins which return the chief part of the
blood from the fingers are superficial and dorsally placed, the arteries are deep and
situated towards the palmar surface. Minute venæ comites however lie on each
side of the digital arteries.
The anterior median plexus is situated on the fore part of the wrist. It is very
irregular in its arrangement, and receives a few small branches from the palm and
from the outer and front part of the thumb.
The superficial radial vein begins at the radial end of the dorsal venous
plexus or arch, and, after receiving veins from the thumb and communicating with
the deep veins accompanying the radial artery, courses up the radial side of the
forearm along with the musculo-cutaneous nerve. It receives numerous branches
from the front and outer surface of the forearm, and a little above the bend of the
elbow, in the slight sulcus at the outer side of the bicipital prominence, unites with
the median cephalic vein to form the cephalic vein (figs. 395, 396). It contains
from four to six valves.
The anterior superficial ulnar vein begins on the inner and front surface of the
wrist, runs up the inner side of the forearm, and joins the posterior ulnar vein
just below the bend of the elbow; or it may unite directly with the median basilic to
form the basilic vein. In the latter case the posterior superficial ulnar vein joins
the basilic (fig. 395). The anterior ulnar vein is accompanied by the anterior
cutaneous nerve. It contains about four valves.
The posterior superficial ulnar vein, larger than the anterior, begins at the
ulnar side of the dorsal plexus. It receives the vena salvatella, or vein of the little
finger, and communicates with the deep ulnar veins by means of an intermuscular
branch which passes beneath the abductor minimi digiti. As it courses upwards
on the posterior aspect of the forearm it receives numerous cutaneous branches,
and near the bend of the elbow joins the anterior superficial ulnar vein. Just
below the internal condyle the united trunk turns forwards to unite with the
median basilic to form the basilic vein. When the basilic is formed by the union.
of the anterior ulnar and median basilic (fig. 395), the posterior ulnar vein may
end in the basilic vein direct. It contains about four valves.
The superficial median vein begins in the anterior plexus in front of the
wrist, and passes up the centre of the front of the forearm, receiving numerous
cutaneous branches, and communicating on each side with the superficial ulnar and
radial veins. At the bend of the elbow it receives the deep median vein, which is
formed by the union of the outer vena comes of the ulnar artery with the muscular
and radial recurrent veins. The short trunk pierces the deep fascia to join the
median vein, which immediately afterwards bifurcates into the median basilic and
median cephalic.
The median cephalic vein, the smaller branch of the median, runs upwards and
outwards in the sulcus between the biceps and supinatus longus, and, joining the



680
THE VEINS
superficial radial vein immediately above the bend of the elbow, forms the cephalic
vein. The musculo-cutaneous nerve passes beneath it, a few fibres of the nerve
lying superficial to it.
The median basilic vein, the larger of the two divisions of the median vein,
runs upwards and inwards across the semilunar fascia of the biceps, by which it is
separated from the brachial artery, to the internal bicipital sulcus, where it joins
one of the superficial ulnar veins or their united trunk to form the basilic. Fibres
of the internal cutaneous nerve pass both in front and behind it. This vein is
FIG. 395.-THE BEND OF THE ELBOW WITH THE SUPERFICIAL VEINS.
(From a dissection by Dr. Alder Smith in the Museum of St. Bartholomew's Hospital.)
Biceps
MEDIAN NERVE
Anastomotica magna
BRANCHES
OF INTERNAL
CUTANEOUS NERVE
Posterior ulnar vein
Brachialis anticus
Anastomotica magna-
artery
Anterior ulnar vein
Median basilic vein
MUSCULAR BRANCH
OF MEDIAN NERVE
Tendon of biceps
Bicipital fascia
Brachialis anticus
Deep median vein
Ulnar artery
Pronator teres
Basilic vein
Brachialis
anticus
Cephalic vein
Brachial artery
EXTERNAL
CUTANEOUS
NERVE
Musculo-spiral n.
and ascend. br. of
radial recur. art.
Radial vein
Median cephalic
vein
Ascending br. of
radial recurrent
RADIAL
NERVE
Radial recurrent
artery
Supinator
longus
Descending br. of
radial recurrent
- Median vein
Radial artery
RADIAL
NERVE
especially prominent at the bend of the elbow; and, on account of its larger size
and superficial position, was usually chosen in venesection when this operation was
in vogue. The lancet, if care was not taken, was liable to pass through the bicipital
fascia and injure the artery, when varicose aneurysm or aneurysmal varix was
a common result.
The cephalic vein, formed by the union of the median cephalic with the super-
ficial radial vein, courses upwards first in the external bicipital sulcus, and then,
in the interval between the pectoralis major and the deltoid, perforates the costo-

CEPHALIC AND BASILIC
681
coracoid membrane, and, crossing the first part of the axillary artery, opens into
the axillary vein. It contains a pair of valves where it joins the axillary vein.
FIG. 396.-SUPERFICIAL VEINS AND LYMPHATICS OF THE FOREARM AND ARM.
External jugular vein
Pectoralis major
Pectoralis major, hooked up
Supraclavicular gland
Jugulo-cephalic vein
Deltoid muscle
Lymphatics from side of
chest
Lymphatics accompanying
cephalic vein
Axillary glands
Pectoral glands-
Cephalic vein
Lymphatic vessels of inner
side of arm
Basilic vein
Biceps, exposed
MUSCULO-CUTANEOUS
NERVE
Brachial artery
Bicipital fascia
Epitrochlear gland
Posterior superficial
ulnar vein
Median basilic vein.
Inner set of superficial.
lymphatics of forearm
Deep median vein
INTERNAL CUTA-
NEOUS NERVE
Anterior superficial
ulnar vein
Median set of superficial
lymphatics of forearm
7
Median cephalic vein
Superficial radial vein
Superficial median vein
Outer set of superficial
lymphatic vessels of fore-
arm
The basilic vein-formed by the union of the median basilic and one of the
superficial ulnar veins or their united trunk-passes up the inner side of the arm.
682
THE VEINS
a little internal to the biceps, and nearly over the course of the brachial artery. At
the junction of the middle with the lower third of the arm it pierces the deep
fascia, and ends by uniting with the inner brachial vena comes to form the axillary
vein.
II. THE DEEP VEINS OF THE UPPER EXTREMITY
The deep veins of the upper extremity accompany their corresponding arteries
and consequently require no detailed description. There are two veins to each
artery below the level of the axilla, known as the companion veins or venæ comites.
In the leg, as will be afterwards noticed, the venæ comites of the main arteries
extend as far as the knee only. The deep veins all contain numerous valves, and
communicate at frequent intervals through intermuscular veins with the superficial.
Beginning at the fingers, two minute veins accompany each digital artery
along the sides of the fingers, and, uniting at the cleft, form interdigital veins
which join the venæ comites of the arteries, forming the superficial palmar arch.
In like manner the veins accompanying the arteries forming the deep arch receive
tributaries corresponding to the branches of that arch. The venæ comites from
the ulnar side of the superficial and deep arches unite at the spot where the ulnar
artery divides into the superficial and deep branch to form two ulnar venæ comites;
whilst those on the radial side of the superficial and deep arch accompany the super-
ficial volar artery and the termination of the radial artery respectively, and unite
at the spot where the superficial volar is given off from the radial artery, to form the
radial venæ comites. The ulnar and radial venæ comites thus formed course up
the forearm with their respective arteries, receiving numerous tributaries from the
muscles amongst which they run, and giving frequent communications to the super-
ficial veins. They finally unite at the bend of the elbow to form the brachial venæ
comites. The ulnar venæ comites receive, before joining the radial, the companion
veins of the interosseous arteries. At the bend of the elbow the deep veins are
connected with the superficial median vein by a short, thick trunk, the deep median
vein.
The brachial venæ comites accompany the brachial artery, the inner vein
receiving at the lower border of either the teres major or subscapularis muscle the
outer vein and the basilic vein, to form a single axillary vein.
The venæ comites of the arteries of the arm anastomose with one another by
frequent cross branches.
The axillary vein is formed by the junction of the inner brachial vena comes
with the basilic vein at the lower border of either the teres major or subscapularis
muscle. It is a vessel of large size, conveying as it does nearly the whole of the
returned blood from the upper extremity. It accompanies the axillary artery through
the axilla, lying to its inner side and at the upper part of the space on a slightly
lower plane. At the outer border of the first rib it changes its name to the sub-
clavian. It has one or two axillary glands in close connection with it, and is
liable, if care is not taken, to be wounded in removing these glands when infiltrated
with cancer secondary to cancer of the breast. The vein contains a pair of valves,
usually placed near the lower border of the subscapularis muscle. It receives in its
course through the axilla :-(1) The subscapular veins which accompany the sub-
scapular artery; (2) the circumflex veins accompanying the circumflex arteries;
(3) the long thoracic veins accompanying the long thoracic artery; (4) numerous
small veins returning the blood from the axillary glands; (5) the veins corresponding
to the branches of the thoracic axis; and (6) the cephalic vein.
The subclavian vein (fig. 329) is the continuation of the axillary. It begins at
the outer border of the first rib, and terminates by joining the internal jugular to


SUBCLAVIAN-INTERNAL SAPHENOUS
683
form the innominate vein opposite the outer part of the sterno-clavicular articulation.
It lies anterior to the subclavian artery and on a lower plane, and is separated from
the artery in the second part of its course by the scalenus anticus muscle. The
subclavian vein, just before the spot where it is joined by the external jugular,
contains a pair of valves.
Tributaries.-Near the outer border of the sterno-mastoid muscle it receives
the external jugular vein. Occasionally the cephalic vein, or a branch from the
cephalic (the jugulo-cephalic), passes over the clavicle to the subclavian (fig. 396).
Chief variations.-(1) The subclavian vein may run on a higher plane than usual, lying
even above the artery. (2) It may pass with the artery behind the scalenus anticus. (3)
It may run behind the scalenus anticus and the artery in front of that muscle. (4) It may
split and enclose the scalenus anticus. (5) It may pass between the clavicle and the sub-
clavius. (6) It may receive directly the transverse cervical, the suprascapular, the anterior
jugular, or the cephalic vein, or the venæ comites of the brachial artery..
6. THE VEINS OF THE LOWER EXTREMITY

The veins of the lower extremity are divided into the superficial and the
deep. The superficial veins lie in the subcutaneous tissue superficial to the deep
fascia, through which they receive numerous communicating branches from the
deep veins. They are collected chiefly into two main trunks, which, beginning
on the foot, extend upwards, one lying antero-internally, and the other postero-
externally. The former finally joins the femoral vein by passing through the
deep fascia at the groin; the latter the popliteal by perforating the fascia at the
ham. The deep veins, on the other hand, accompany their corresponding arteries.
Below the knee there are two veins to each artery; above it, excepting at the back
of the thigh, there is only one vein to each artery. All the veins of the lower limb
have valves which are more numerous than in the veins of the upper extremity,
and in the deep than in the superficial veins.
I. THE SUPERFICIAL VEINS OF THE LOWER EXTREMITY

The superficial veins of the lower limb are collected into two main trunks.
One, the long or internal saphenous, which is placed antero-internally; the other,
the short or external saphenous, which is placed postero-externally. These veins
commence on the dorsum of the foot in an irregular arch, which stretches across
the instep with its convexity towards the toes. The arch receives branches from
the four outer toes and dorsum of the foot, and one branch of somewhat larger size
than the rest from the inner side of the great toe. It also communicates with the
venæ comites accompanying the dorsal artery of the foot (fig. 397).
The long or internal saphenous vein commences on the inner side of the foot at
the inner end of the above described venous arch, and, after receiving branches from
the sole which join it by turning over the inner border of the foot, passes upwards
in front of the inner ankle, and then obliquely upwards and backwards about a
finger's breadth from the posterior border of the tibia in company with the internal
saphenous nerve, which becomes superficial just below the knee. Continuing its
course upwards, it passes behind the internal condyle, and then runs upwards and
somewhat outwards on the inner side of the front of the thigh to about an inch
and a half below Poupart's ligament, where, after receiving the superficial circumflex


684
THE VEINS
FIG. 397. THE SUPERFICIAL VEINS AND LYMPHATICS OF THE LOWER LIMB.
Superficial epigastric vein -
Lymphatics from penis
and scrotum
Common femoral vein-
Superficial femoral.
lymphatic glands
Superficial external pudic
vein
Superficial lymphatics
from lateral wall of
abdomen
Superficial lymphatics
from lower and anterior
walls of abdomen
Superficial inguinal
lymphatic glands
-Superficial circumflex
iliac vein
Internal femoral cutaneous-
vein
External femoral
cutaneous vein
Long saphenous vein.
INTERNAL MALLEOLUS
Dorsal venous arch

EXTERNAL SAPHENOUS
685
iliac, superficial epigastric, and superficial external pudic veins, it dips through
the saphenous opening in the fascia lata, and ends in the femoral vein. In its
course up the leg and thigh it receives numerous unnamed cutaneous branches,
and at variable intervals communicates with the deep veins. Just before it passes
through the saphenous opening, it often receives a large vein (external femoral
cutaneous) formed by the union of several of the cutaneous veins on the upper and
outer part of the thigh, and a second vein (the internal femoral cutaneous) formed
by the union of the cutaneous veins from the inner and back part of the thigh.
The long saphenous vein contains from ten to twenty valves.
The short or external saphenous vein begins at the outer end of the venous
arch, or plexus, on the dorsum of the foot. After receiving branches from the sole,
which turn over the outer border of the foot, it passes behind the outer ankle, and
then upwards and inwards, lying at first along the outer side of the tendo Achillis,
afterwards along the back of the calf, in company with the external or short
saphenous nerve, to about the lower part of the centre of the popliteal space,
where it perforates the deep fascia, and, sinking between the two heads of the
gastrocnemius, opens into the popliteal vein. As it passes up the calf between
the superficial and deep fascia, it receives numerous cutaneous veins from the heel,
and the outer side and back part of the leg, and communicates at intervals, through
transverse or intermuscular branches, with the deep veins (venæ comites) accom-
panying the peroneal artery. Just before perforating the deep fascia, it receives a
large descending branch from the lower and back part of the thigh, and sends
upwards and inwards a communicating vein to the long saphenous. A small
offshoot from the inferior sural branch of the popliteal artery accompanies the vein
for a short distance down the back of the calf. The short saphenous vein contains
from nine to twelve valves.

II. THE DEEP VEINS OF THE LOWER EXTREMITY

The deep veins of the lower extremity accompany the arteries, and have
received corresponding names. From the foot to the knee there are two veins
to each artery. These veins run on either side of the corresponding artery, and
communicate at frequent intervals with each other across it They are known as
the venæ comites. From the knee upwards there is a single vein to each artery,
except at the back of the thigh and in the gluteal region, where there are com-
monly two.
The veins of the foot and leg.-The venæ comites of the internal and ex-
ternal plantar arteries, after receiving small veins corresponding to the branches
of these vessels, unite, beneath the abductor hallucis muscle, to form the venæ
comites of the posterior tibial artery. These, again, receive, at the spot where
the peroneal artery is given off from the posterior tibial, the venæ comites of
the peroneal artery, which are formed in like manner by the confluence of the
various veins corresponding to the branches of that vessel. Opposite the lower
border of the popliteus muscle, the posterior tibial veins unite with the anterior
tibial veins, which pass through the upper part of the interosseous membrane with
the anterior tibial artery, to form the popliteal. The anterior tibial veins are the
continuation of the venæ comites of the dorsal artery of the foot, which, in their
turn, are formed by the confluence of the veins accompanying its various branches.
The anterior tibial venæ comites thus formed run with the anterior tibial artery
up the front of the leg, and, after passing through the interosseous membrane along
with the artery, join the posterior tibial veins to form a single popliteal.
All these veins contain numerous valves, and communicate, by means of inter-
muscular branches, with the superficial veins.
686
THE VEINS
The popliteal vein is formed by the confluence of the venæ comites of the
anterior and posterior tibial arteries at the lower border of the popliteus, and extends
upwards to the opening in the adductor magnus at the junction of the middle and
lower third of the thigh, where it changes its name to femoral. It accompanies the
popliteal artery, lying superficial to it in the whole of its course, and tightly bound
down to it by its fascial sheath. At the lower part of the space it is a little internal
to the artery, but, crossing the vessel obliquely as it ascends, lies a little external
to it at the upper part of the space. The internal popliteal nerve lies superficial
to the vein, being external to it above, then on it, and then a little to its inner
side. The popliteal vein contains two or three valves.
The chief variations of the popliteal are:-(1) It may lie between the artery and the bone.
(2) It may be double through a part or the whole of the popliteal space. (3) Two veins by
frequently uniting in front and behind the artery may form a kind of plexus around the
vessel. (4) It may be shorter than usual in consequence of a high union of the tibial venæ
comites.
The femoral vein, the continuation of the popliteal upwards, extends from the
tendinous opening in the adductor magnus to an inch and a half below Poupart's
ligament where it joins the profunda vein to form the common femoral vein. In
this course its relations are similar to those of the superficial femoral artery. As
the vein passes through Hunter's canal, it lies behind and a little external to the
artery. At the apex of Scarpa's triangle it is still posterior to the artery, but
gradually passes to the inner side as it ascends through that space. It contains
three pairs of valves. The close connection of the vein to the artery should
be remembered in the operation of ligature. The sheath should be opened on its
inner side, that is, well over the artery, and the point of the aneurysm needle kept
closely applied to the artery lest it perforate the overlapping vein.
Tributaries. (1) The venæ comites of the anastomotica magna artery; (2) the
venæ comites corresponding to the muscular branches of the femoral.
The profunda or deep femoral vein accompanies the profunda or deep femoral
artery, and receives the venæ comites corresponding to its various branches.
Unlike the other veins of the lower extremity, it lies in front of its companion
artery, and is at first a little internal to it. It terminates by joining the super-
ficial femoral vein about an inch and a half below Poupart's ligament in the angle
between the femoral and profunda arteries. It contains five valves.
The common femoral vein is a short thick trunk corresponding to the common
femoral artery. It is formed by the confluence of the superficial femoral and
profunda veins about an inch and a half below Poupart's ligament, and is con-
tinued upwards to the lower border of that structure, where it takes the name
of external iliac. It lies on the same plane as the common femoral artery, but
internal to that vessel, from which it is separated by a delicate prolongation
of fascia stretching between the front and back layers of the femoral sheath.
Internally, it is separated by a similar septum of fascia from the crural canal.
It usually contains two valves: one just above the junction with the profunda vein,
the other just below Poupart's ligament (fig. 372).
Tributary. The long saphenous vein which reaches it by passing through the
saphenous opening in the deep fascia.
Chief variations. (1) The femoral vein may be double in part or in whole of its length.
(2) It may split into two and embrace the femoral artery. (3) It may pass through the
adductor magnus above the femoral artery and run separate from the artery until it joins
the profunda vein to form the common femoral vein. (4) It may run with the sciatic nerve
and pierce the adductor magnus at the level of the lesser trochanter. When this occurs
the femoral artery is usually very small, and the sciatic artery is the chief nutrient vessel
of the thigh.
The external iliac vein is the continuation upwards of the common femoral.
Beginning at the lower border of Poupart's ligament it accompanies the external


EXTERNAL ILIAC
687
iliac artery upwards and inwards along the brim of the pelvis, lying at first on the
horizontal ramus of the pubes, and then on the psoas muscle. It terminates in the
common iliac vein by joining the internal iliac vein behind the internal iliac artery
opposite the lower border of the sacro-iliac synchondrosis. It lies at first internal
to the external iliac artery, and on the left side remains internal to the artery
throughout its course. On the right side, however, as it ascends, it gradually gets
a little behind the artery. It contains one or two valves.
Tributaries. (1) The deep epigastric vein, formed by the union of the venæ
comites of the deep epigastric artery, joins the external iliac just above Poupart's
ligament. (2) The deep circumflex iliac vein, which is formed in the same way
by the confluence of the venæ comites of the deep circumflex iliac artery, joins the
external iliac vein a little higher.

THE LYMPHATICS
TH HE lymphatics consist of lymphatic vessels and lymphatic glands. The
lymphatic vessels carry lymph, and the lymphatics of the intestine chyle as
well whilst digestion is going on. The chyle-carrying lymphatics are generally known
as lacteals. The lymphatic glands are situated at certain spots in the course
of the lymphatic vessels. The lymphatic vessels ultimately terminate either in
the left or right lymphatic duct. The former, some eighteen inches in length,
known as the thoracic duct, begins at the confluence of certain lymphatics in
the abdomen, passes through the thorax, and terminates in the left innominate
vein at the confluence of the left internal jugular and subclavian veins. It receives
the lymphatics of both lower extremities, the lymphatics of the abdomen, except
those from the convex surface of the liver, the lymphatics from the left half of the
thorax, the left half of the head and neck, and the left upper extremity. The right
lymphatic duct is a short vessel a little less than an inch in length. It receives
the lymphatics from the convex surface of the liver, the right half of the thorax,
the right side of the head and neck, and the right upper extremity. It ends in the
right innominate vein at the confluence of the right internal jugular and subclavian
veins.
The thoracic duct, or left lymphatic duct, is described with the LYMPHATICS OF
THE THORAX; the right lymphatic duct with the LYMPHATICS OF THE HEAD AND
NECK.

ง
THE LYMPHATICS OF THE HEAD AND NECK
The lymphatics of the head and neck are divided into the superficial and
the deep. The superficial roughly follow the course of the superficial veins.
Streaming down the scalp and face, they enter the neck through corresponding
groups of superficial glands, and then converge to join the superficial cervical
chain and in part the deep cervical chain of glands which are situated along
the course of the external and internal jugular veins respectively. The deep
lymphatics of the head and neck follow roughly the course of the deep arte-
ries. They include the lymphatics from the interior of the cranium; from
the orbit; from the interior of the nose and mouth; from the tongue; from the
pharynx, larynx, and upper part of the trachea and oesophagus, and from the
thyroid gland. After passing through certain glands in their course, they terminate
chiefly in the deep cervical chain of glands. The deep cervical chain of glands,
after receiving the lymphatics from the superficial chain, ends in the thoracic duct
on the left side, and in the right lymphatic duct on the right side.

SUPERFICIAL LYMPHATICS OF HEAD AND NECK 689
I. THE SUPERFICIAL LYMPHATIC VESSELS AND GLANDS
OF THE HEAD AND NECK
A. THE SUPERFICIAL LYMPHATIC VESSELS
The superficial lymphatic vessels may be subdivided into the superficial
lymphatics of the scalp, the face, and the neck (fig. 398).
1. The superficial lymphatic vessels of the scalp follow roughly the course of
the superficial veins. Thus there is (1) a posterior or occipital set, which course
downwards over the occipital bone to the occipital, or suboccipital glands as they
are sometimes called; (2) a postero-lateral or posterior auricular set, which course
downwards behind the ear, and end in the posterior auricular or sterno-mastoid
glands; (3) an antero-lateral or temporal set, which accompany the superficial
temporal vein in front of the ear, and end in the parotid lymphatic glands; and
(4) an anterior or frontal set, which course downwards over the frontal bone and
end in the facial lymphatics.
2. The superficial lymphatic vessels of the face-continuous at the root of the
nose with the frontal set of lymphatics descending from the scalp-course downwards
and backwards with the facial vein, receiving tributaries from the inner half of the
eyelids, the side of the nose, the contiguous portions of the cheek, and the upper and
lower lips. They end in the submaxillary lymphatic glands beneath the lower jaw.
The lymphatics from the outer part of the eyelids and the outer part of the cheek
run backwards and slightly downwards to the parotid lymphatic glands.
3. The superficial lymphatic vessels of the neck form a plexus in the sub-
cutaneous tissues of the neck. They communicate with the superficial lymphatics
of the scalp and face, and with some of the superficial lymphatics of the upper part
of the thorax. They end in the superficial cervical chain of lymphatic glands.

B. THE SUPERFICIAL LYMPHATIC GLANDS
The superficial lymphatic glands of the head and neck may be divided into
two sets, a transverse and a vertical (fig. 398).
1. The transverse occur in groups in the course of a line drawn from the
occiput to the mastoid process, and thence along the zygoma and beneath the body
of the lower jaw to the symphysis. They receive as afferent vessels the lymphatics
of the scalp and face. Their efferent vessels pass into the superficial and deep
cervical chains.

or
They are named :-(1) The occipital, or suboccipital; (2) the posterior auricular,
or sterno-mastoid; (3) the parotid; (4) the buccal; and (5) the submaxillary.
(1) The occipital or suboccipital glands are situated at the back of the head,
beneath the skin, just below the superior curved line of the occipital bone and over
the insertion of the complexus muscle. They receive the lymphatic vessels from
the back of the head. Their efferent vessels discharge into the superficial lymphatic
glands of the neck. It is these glands which perhaps more especially are found
enlarged in secondary syphilis.
(2) The posterior auricular or sterno-mastoid glands, situated over the inser-
tion of the sterno-mastoid muscle behind the ear, receive the posterior auricular
lymphatics. Their efferent vessels discharge into the superficial cervical lymphatics.
(3) The parotid lymphatic glands are situated just in front of the ear over
the parotid salivary gland, in the substance of which one or more are embedded.
They receive the temporal set of lymphatic vessels, and the lymphatics from the
external parts of the eyelid and posterior and greater part of the cheek. They

Y Y

690
THE LYMPHATICS
discharge, partly into the submaxillary glands, and partly into the superficial
cervical chain.
(4) The buccal lymphatic glands are situated on the surface of the buccinator.
Some of the facial lymphatics pass through these on their way to the submaxillary
glands.
(5) The submaxillary lymphatic glands are situated in the digastric triangle,
beneath the body of the lower jaw. They vary from eight to twelve in number.
FIG. 398. THE SUPERFICIAL LYMPHATICS OF THE SCALP, FACE, AND NECK.
Frontal vein
Supraorbital vein-
Communication with
ophthalmic vein
Transverse nasal vein-
Angular vein-
Lateral nasal veins
Transverse facial vein-
Superior labial or
coronary vein
Anterior pterygoid or-
deep facial vein
Inferior coronary vein
Facial vein
Inferior labial vein
Submental vein
Lingual vein
Superior thyroid vein
Middle thyroid vein
Anterior jugular vein
Anterior temporal vein
Posterior temporal vein
Deep temporal vein
Parotid lymphatic glands
Common temporal vein
-Internal maxillary vein
Occipital vein
Temporo-maxillary vein
Posterior auricular vein
Occipital lymphatic glands
Sterno-mastoid lymphatic
glands
Communication between
facial and external
jugular veins
Submaxillary lymphatic
glands
Internal jugular vein
Posterior external
jugular vein
External jugular vein
Superficial cervical chain
of glands
Communication between
anterior jugular veins
Transverse cervical vein
Suprascapular vein
Jugulo-cephalic vein
They receive some of the lymphatics from the face, i.e. from the upper and lower
lips and side of the nose; the lymphatics from the floor of the mouth, from the
front part of the tongue, and from the sublingual and submaxillary salivary glands,
and the anterior efferent vessels from the parotid lymphatic glands. Their efferent
vessels terminate partly in the deep, and partly in the superficial cervical lymphatic
glands. Two or three glands situated in the middle line between the anterior bellies
of the digastric muscles are sometimes distinguished as the suprahyoid lymphatic
glands.
do
DEEP LYMPHATICS OF HEAD AND NECK
691
2. The vertical set of superficial glands of the neck-four to six in number,
known as the superficial cervical chain-are situated chiefly in the posterior triangle
of the neck, along the course of the external jugular vein, between the platysma and
the deep fascia. Small superficial glands are also found in the front of the neck
between the hyoid bone and the sternum, and posteriorly over the trapezius muscle.
The superficial cervical glands receive the vessels from the occipital glands, and
from the posterior auricular glands, and part of those from the parotid and
submaxillary glands. They also receive the lymphatics from the integuments of
the neck and from the external ear. Their efferent vessels open into the deep
chain of cervical glands.
II. THE DEEP LYMPHATIC VESSELS AND GLANDS
OF THE HEAD AND NECK
A. THE DEEP LYMPHATIC VESSELS OF THE HEAD AND NECK
The deep lymphatic vessels of the head and neck may be divided into the
lymphatics of the cranium, the orbit, the temporal and zygomatic fossæ, the nose,
the mouth and tongue, the pharynx, the larynx, the upper part of the œsophagus
and trachea, and the thyroid body. They roughly follow the course of the deep
arteries, and terminate in the deep cervical chain of lymphatic glands which accom-
pany the common carotid artery and internal jugular vein.
1. The lymphatics from the interior of the cranium are divided into the
meningeal and the cerebral. The meningeal accompany the meningeal arteries
through the various foramina in the base of the skull, and terminate in the deep
cervical chain. The cerebral lymphatics pass in like manner with the cerebral
vessels (the internal carotid and vertebral arteries, and the internal jugular
vein), through the corresponding foramina in the base of the skull, and join
the deep lymphatic chain. The origin of the cerebral lymphatics and the
lymphatics from the choroid plexus are described in the ANATOMY OF THE BRAIN
(page 717).
2. The lymphatics of the orbit pass with the infraorbital vein into the spheno-
maxillary fossa, and thence with the internal maxillary vein into the internal
maxillary and deep parotid glands. (For description of the lymphatics of the
eyeball, see page 889.)
3. The lymphatics from the temporal and zygomatic fossæ run with the
arteries in these situations, and, after passing through the internal maxillary glands,
join the deep cervical chain.
4. The lymphatics from the interior of the nose accompany the arteries
supplying that cavity, and terminate, in part in the lymphatics of the pharynx, but
chiefly in the deep cervical chain. They communicate, through the lymphatic
spaces which surround the olfactory nerves, with the subdural and subarachnoid
lymph-spaces of the cranium.
5. The lymphatics of the mouth and tongue.-The lymphatics from the floor
of the mouth pass through the mylo-hyoid muscle into the submaxillary lymphatic
glands. The lymphatics of the lips pass with the superficial lymphatics, partly
into the submaxillary glands, and partly into the deep cervical chain. The
lymphatics of the deep surface of the cheek and of the roof of the mouth join the
internal maxillary lymphatic glands. The lymphatics of the tongue run back-
wards with the ranine vein, and, after passing through several small lingual glands
on the hyo-glossus muscle, join the deep cervical chain. The lymphatics of the
front part of the tongue pass with the lymphatics of the floor of the mouth,
through the mylo-hyoidean muscles into the submaxillary glands.


YY 2
692
THE LYMPHATICS
6. The lymphatics of the pharynx run along the course of the pharyngeal
arteries and enter the upper set of deep cervical glands. Those from the upper
part of the pharynx pass through the post-pharyngeal gland. The lymphatics of
the tonsil open into the submaxillary glands near the angle of the jaw.
7. The lymphatics of the larynx join the deep cervical glands. Those above
the glottis pierce the thyro-hyoid membrane, and end in the upper set of the deep
cervical glands; those below the glottis perforate the crico-thyroid membrane,
and, after passing through one or more small laryngeal glands at the lower part
of the larynx on its anterior or lateral aspect, enter the lower set of the deep
cervical glands.
8. The lymphatics of the upper part of the oesophagus and trachea join the
lower glands of the deep cervical chain.
9. The lymphatics of the thyroid body accompany the thyroid arteries, and
end in part in the upper and in part in the lower glands of the deep cervical chain.
B. THE DEEP LYMPHATIC GLANDS OF THE HEAD AND NECK
1. The deep lymphatic glands of the head are few in number. They are the
lingual, the internal maxillary, and the post-pharyngeal.
(1) The lingual, two to four in number, are situated on the outer surface of
the hyo-glossus and genio-hyo-glossus muscles. They receive lymphatics from the
upper surface and posterior part of the substance of the tongue. Their efferent
vessels terminate in the superior glands of the deep cervical chain.
(2) The internal maxillary or deep facial glands, three to six in number, are
situated by the side of the pharynx immediately behind the buccinator muscle.
They receive the lymphatics from the orbit, the nose, the temporal and spheno-
maxillary fossæ, the upper jaw, the palate, and the pharynx. Their efferent vessels
join the superior glands of the deep cervical chain.
(3) The post-pharyngeal gland is situated behind the pharynx on the rectus
capitis anticus major near the base of the skull. It receives lymphatics from the
upper part of the pharynx, from the nose, and from the deep prevertebral muscles.
2. The deep lymphatic glands of the neck are divided into the upper and
the lower.
The upper set extend along the course of the internal jugular vein from the
base of the skull to about the level of the thyroid cartilage. They receive the
lymphatics from the interior of the cranium above; the lymphatics from the deep
muscles of the upper part of the neck behind; and the lymphatics from the internal
maxillary glands, the posterior half of the tongue, the middle portion of the pharynx,
the upper part of the larynx, the upper part of the thyroid body, and some of the
efferent vessels from the submaxillary lymphatic glands in front and internally.
Their efferent vessels pass downwards to the lower deep cervical glands.
The lower deep cervical glands follow the course of the internal jugular vein
from the thyroid cartilage to near the clavicle. They receive the lymphatics from
the lower part of the neck, the efferent vessels from the superior set of deep
cervical glands, the lymphatics from the lower part of the larynx, the lower part
of the thyroid body, the upper part of the trachea and oesophagus, and the efferent
vessels from the superficial cervical glands. Their efferent vessels end in the jugular
lymphatic trunk, which unites with the subclavian lymphatic trunk, on the right
side to form the right lymphatic duct, and on the left side to end in the thoracic duct.
The right jugular trunk may also receive the lymphatics coming from the right
half of the superior and anterior mediastina.
The right lymphatic duct. The right lymphatic duct is a short vessel from
half to three-quarters of an inch long. It receives the lymphatics from the right
side of the head and neck, from the right upper extremity, most of the lymphatics


LYMPHATICS OF UPPER EXTREMITY
693
from the right side of the thorax, and part of the lymphatics from the convex
surface of the liver. It passes downwards and inwards from its formation at the
union of the subclavian and jugular lymphatic trunks, and ends at the confluence
of the right internal jugular and subclavian veins. Its entrance is guarded by a
double valve.
THE LYMPHATICS OF THE UPPER EXTREMITY
The lymphatics of the upper extremity-consisting of both lymphatic vessels and
lymphatic glands-are arranged in two sets, a superficial and a deep. The former
are situated in the subcutaneous tissue between the skin and the deep or muscular
fascia, the latter along the course of the arteries of the limb. Both sets converge
as they approach the axilla, and unite in the axillary glands. The efferent vessels
of these glands form one or more trunks, which open, on the left side, into the
thoracic duct, and, on the right side, into the right lymphatic duct.
I. THE SUPERFICIAL LYMPHATIC VESSELS AND GLANDS
OF THE UPPER EXTREMITY
1. The superficial lymphatic vessels begin around the matrix of the nail
and in the pulp of the finger. Thence they run upwards, in the form of four main
channels, along the side of the finger-two on the dorsal and two on the palmar
aspect.
The palmar set end on the convexity of a lymphatic palmar arch. From the
arch, lymphatic vessels run up the forearm, more or less in two sets-an outer and
an inner-roughly following the course of the superficial veins; a third or median
set, starting as a plexiform arrangement in front of the wrist, runs up between the
other two. The communication, however, between the three main sets of vessels
is so free that, when they are minutely injected, the front of the forearm appears
covered with a dense plexus of lymphatics (fig. 399)."
The dorsal set of digital lymphatics ends in a plexus on the back of the hand.
From this plexus numerous lymphatic vessels stream up the back of the forearm,
and, winding round the inner and outer borders respectively of the limb, join the
lymphatics on the anterior aspect.
From the bend of the elbow the lymphatics run up the arm, the greater
number following the course of the basilic vein, and, dipping beneath the pectoralis
major, converge to end in the axillary glands. The lymphatics from the outer side
of the arm run in chief part obliquely across the biceps, towards the axilla; but
a few accompany the cephalic vein to the infraclavicular lymphatic glands. The
lymphatics over the deltoid also mainly end in these glands.
2. The superficial lymphatic glands are few in number. There are none, as a
rule, below the bend of the elbow. Occasionally there is one at the bend of the
elbow, and constantly two or three are found above the internal condyle (epitrochlear
glands), in the course of the lymphatic vessels running with the basilic vein.


II. THE DEEP LYMPHATIC VESSELS AND GLANDS OF
THE UPPER EXTREMITY
1. The deep lymphatic vessels accompany the arteries of the upper extremity.
Hence in the forearm they are found along the course of the radial, the ulnar, the
anterior interosseous, and the posterior interosseous arteries. At the bend of the

694
THE LYMPHATICS
FIG. 399. THE SUPERFICIAL LYMPHATICS OF THE UPPER LIMB AND
AXILLARY GLANDS.
External jugular vein
Pectoralis major
Pectoralis major, hooked up
Supraclavicular gland
Jugulo-cephalic vein
Deltoid muscle
Lymphatics from side of -
chest
Lymphatics accompanying
cephalic vein
Axillary glands
Pectoral glands
Cephalic vein
-Lymphatic vessels of inner
side of arm
Basilic vein.
Epitrochlear gland-
Posterior superficial
ulnar vein
Median basilic vein.
Inner set of superficial.
lymphatics of forearm
Deep median vein
INTERNAL CUTA-.
NEOUS NERVE
Anterior superficial.
ulnar vein
Median set of superficial
lymphatics of forearm
Biceps, exposed
MUSCULO-CUTANEOUS
NERVE
-Brachial artery
- Bicipital fascia
Median cephalic vein
Superficial radial vein
Superficial median vein
Outer set of superficial
lymphatic vessels of fore-
arm
elbow they converge, and follow the course of the brachial and axillary arteries to
the axilla, and there end, together with the superficial lymphatics of the upper
extremity and the superficial lymphatics from the side of the chest and back of
LYMPHATICS OF UPPER EXTREMITY
695
the shoulder, in the axillary lymphatic glands. They communicate with the
superficial lymphatics at the wrist.
2. The deep lymphatic glands.-A few small glands are occasionally found in
the course of the lymphatic vessels accompanying the arteries of the forearm, and,
more often, a few in the course of those accompanying the brachial artery. But
the first important set of deep glands is met with in the axilla.
The axillary glands are numerous and of large size. They are about twelve in
number. They are arranged in four chief sets-a median set, three or more in
number, situated along the course of the axillary artery and vein (axillary
glands proper); an inner or anterior set, four or five in number, situated below the
greater pectoral muscles in the course of the long thoracic artery, on the outer
surface of the serratus magnus (pectoral glands); a posterior or external set,
usually two in number, situated along the course of the subscapular artery, under
cover of the latissimus dorsi (subscapular glands); and a superior set, usually two
in number, situated just below the clavicle close to the cephalic vein, upon the
costo-coracoid membrane in the fossa beneath the pectoralis major and deltoid
(subclavian or infraclavicular glands).
The axillary glands proper, or the glands along the course of the axillary artery
and vein, receive the larger number of lymphatics from the arm. The pectoral
glands receive the lymphatics from the mammary gland, the side of the chest, and
the integument of the upper portion of the abdominal wall. The subscapular
glands receive the lymphatics from the integuments of the back. The infraclavicular
glands receive the lymphatics from the outer part of the arm and integuments
covering the deltoid. They communicate, above with the cervical lymphatics, and
below with the other glands in the axilla. The efferent vessels from all these
glands run upwards along the subclavian vein, and enter the neck either as four
distinct trunks, or as a single trunk (the axillary lymphatic trunk), and terminate
on the left side in the thoracic duct, and on the right side in the right lymphatic
duct.
The communication between the glands in the axilla is very free. Thus, in
secondary infiltration following carcinoma of the breast, although the pectoral
glands may at first be alone affected, the remaining sets generally become also
involved.
THE LYMPHATICS OF THE THORAX
The lymphatics of the thorax may be divided into the parietal, which ramify in
the thoracic walls; and the visceral, which receive the lymph from the thoracic
viscera. The thoracic duct, which conveys the lymph from the lower extremities
and from the greater part of the abdomen, passes through the posterior mediastinum
on its way to the confluence of the left internal jugular and subclavian veins at the
root of the neck, and is described here with the lymphatics of the thorax.

I. THE PARIETAL LYMPHATIC VESSELS AND GLANDS
OF THE THORAX
1. The parietal lymphatic vessels are divided into the superficial and the deep.
The superficial parietal lymphatics ramify beneath the integuments, over the
pectoralis major in front, the serratus magnus laterally, and the trapezius and
696
THE LYMPHATICS
latissimus dorsi behind. They all converge towards the axilla, and end in the
axillary glands. The lymphatics of the mammary gland end for the most part in
the pectoral set of the axillary glands, but those from the inner portion of the
gland pass through the second, third, and fourth intercostal spaces into the internal
mammary lymphatic chain of glands, and thus open into the thoracic duct on the
left, and the right lymphatic duct on the right side. According to Macalister, the
lymphatics from the nipple and areola pass more deeply into the axilla, and end in
one of the axillary glands, placed nearer to the clavicle than the pectoral set.
The deep parietal lymphatics are subdivided into (1) the intercostal and (2) the
diaphragmatic.
(1) The intercostal lymphatics accompany the intercostal arteries and receive
the lymph from the intercostal muscles and the parietal pleura. Those in the
anterior part of the intercostal space run forwards and end in the internal
mammary or anterior intercostal lymphatic glands. Those in the posterior part of
the space run backwards, and-after receiving the dorsal lymphatic vessels which
accompany the dorsal branches of the intercostal arteries between the transverse
processes of the vertebræ, and return the lymph from the muscles of the back and
from the spinal canal-end in the intercostal or posterior intercostal lymphatic
glands.
(2) The diaphragmatic lymphatics follow the vessels of the diaphragm. They
terminate, anteriorly in the internal mammary and anterior mediastinal lymphatic
glands; postero-laterally in the lower intercostal lymphatics and in the lymphatics
accompanying the musculo-phrenic artery; and posteriorly in the posterior medi-
astinal glands. The lymphatics from the vertebral portion of the diaphragm end
in the lumbar glands (see LYMPHATICS OF ABDOMEN, page 701). Some of the
lymphatics from the right side join the hepatic lymphatics.
2. The parietal lymphatic glands are also divided into the superficial and the
deep.
The superficial parietal glands.-The three or four glands along the lower
border of the pectoralis, major, described here as the pectoral set of the axillary
glands, are by some authors classed as superficial thoracic glands. They receive
the lymphatics from the front of the chest, and some of the lymphatics of the
mammary gland. There is also occasionally a superficial gland a little below the
ensiform cartilage called the epigastric gland. It receives, when present, some of
the lymphatics from the lower anterior chest walls and upper part of the abdomen.
The deep parietal glands are:-(1) The internal mammary, sternal, or anterior
intercostal; and (2) the intercostal or posterior intercostal.
(1) The internal mammary, sternal, or anterior intercostal glands lie along
the course of the internal mammary artery behind the costal cartilages of the true
ribs. There is usually one gland corresponding to each intercostal space. These
glands receive the lymphatics from the anterior part of the intercostal spaces, the
lymphatics ascending with the superior epigastric artery from the abdominal walls,
the lymphatics accompanying the musculo-phrenic artery from the diaphragm
and lower intercostal spaces, and the lymphatics from the inner portion of the
mammary gland. The efferent vessels from the uppermost glands join the thoracic
and right lymphatic ducts respectively, but some of the efferent vessels of the
lower glands join the anterior mediastinal glands.
(2) The intercostal or posterior intercostal lymphatic glands lie in the posterior
end of each intercostal space about the level of the heads of the ribs. They receive
the lymphatics accompanying the intercostal vessels from the posterior parts of
the intercostal spaces, and the lymphatics from the deep muscles of the back, and
from the spinal canal. The lowermost also receive some of the lymphatics from
the diaphragm. On the left side their efferent vessels open into the thoracic duct.
On the right side the efferent vessels from the lower glands also join the thoracic


VISCERAL LYMPHATICS OF THORAX
697
duct, but the vessels from the upper glands may join the efferent vessels from
the bronchial glands (the bronchio-mediastinal trunk) and open into the right
lymphatic duct.
II. THE VISCERAL LYMPHATIC VESSELS AND GLANDS
OF THE THORAX
1. The visceral lymphatics of the thorax include those from the heart and
pericardium, the lungs and visceral pleura, the oesophagus and the thymus gland,
with the glands into which these lymphatics respectively open-namely, the anterior
mediastinal, the superior mediastinal, the posterior mediastinal, and the bronchial.
The lymphatics of the pericardium end in front in the anterior mediastinal
and superior mediastinal glands, and behind in the posterior mediastinal glands.
The lymphatics of the heart begin at the apex, and follow the coronary vessels
to the base, where they leave the pericardium, and unite to form a right and left
trunk. The former passes over the arch of the aorta, then through one of the
superior mediastinal or cardiac glands, and thence backwards to the trachea, on
which it runs to join the right lymphatic duct at the root of the neck. The left
trunk courses along the pulmonary artery, and, at the bifurcation of that vessel,
passes through one of the posterior mediastinal glands behind the arch of the
aorta, and thence runs up the left side of the trachea to end in the thoracic duct.
The lymphatics of the visceral pleura and lung form a superficial set beneath
the pleura, and a deep set which accompanies the pulmonary vessels and bronchial
tubes. At the root of the lung the superficial join the deep, which then enter the
bronchial glands.
The lymphatics of the thoracic portion of the esophagus begin as a plexus
between the mucous membrane and the muscular coat, perforate the latter, and
terminate in the posterior mediastinal glands.
The lymphatics of the thymus terminate in the superior mediastinal glands.
2. The visceral lymphatic glands are the anterior mediastinal, the superior
mediastinal, the posterior mediastinal, and the bronchial.
The anterior mediastinal or sternal glands lie in front of the pericardium.
behind the sternum in the loose tissue of the anterior mediastinum. They receive the
lymphatics from the antero-median portion of the diaphragm, the front of the
pericardium and heart, some of the efferent vessels from the lower internal mammary
lymphatic glands, and the lymphatics from the convex surface of the right lobe of
the liver. Their efferent vessels pass upwards to the superior mediastinal glands.
The superior mediastinal or cardiac glands lie in front of the upper part of
the pericardium, the arch of the aorta, and left innominate vein. They receive
the lymphatics from the anterior mediastinal glands, from the upper and front part
of the pericardium and right side of the heart, and from the thymus gland. Their
efferent vessels run up the sides of the trachea to join the thoracic duct and right
lymphatic duct respectively.
The posterior mediastinal glands are situated in the posterior mediastinum
along the course of the aorta and oesophagus. They receive lymphatics from the
back of the pericardium and left side of the heart, from the oesophagus, from the
posterior part of the diaphragm, and a few from the right border of the liver.
Their efferent vessels pass chiefly into the thoracic duct; a few into the bronchial
glands.
The bronchial glands are placed between the divisions of the bronchi at the
root of the lung (pulmonary glands), and about the bifurcation of the trachea
(tracheal glands). The larger glands, situated at the bifurcation of the trachea,
are twenty or thirty in number. They receive the lymphatics from the lung and


698
THE LYMPHATICS
visceral pleura; also some of the lymphatics from the trachea and from the back
of the heart and pericardium, and a few of the efferent vessels of the posterior
mediastinal glands. Their efferent vessels, with the efferent vessels of the superior
mediastinal or cardiac glands, pass up the sides of the trachea, and on the right
side either terminate directly in the right lymphatic duct, or join with the efferent
vessels of the intercostal glands to form a common trunk, the broncho-mediastinal
trunk, and thus open into the right lymphatic duct. On the left side they open
directly into the thoracic duct, or first form, as on the right side, a broncho-
mediastinal trunk.
In early life they are of a pinkish colour, but as life advances they become
bluish, and later almost black, from the deposit of pigment arrested in them in its
passage from the lungs.
THE THORACIC DUCT
The thoracic duct begins in the abdomen at the receptaculum chyli opposite
the first or second lumbar vertebra, enters the thorax through the aortic opening
of the diaphragm, runs up the posterior mediastinum to the right of the aorta,
crosses behind the aortic arch, and, leaving the thorax at the superior opening,
ascends on the left side of the neck as high as the seventh cervical vertebra, and,
finally curving over the apex of the left pleura and subclavian artery, ends in the
confluence of the left internal jugular and subclavian veins.
The duct is about eighteen inches long, and pursues a tortuous course. It
contains many double valves which, when the duct is dilated, cause it to be con-
stricted at intervals, and give it somewhat the appearance of a string of beads.
The valves are more numerous in the upper than in the lower part of the duct.
At its entrance into the innominate vein there are two perfect valves, which
effectually prevent any regurgitation of lymph or entrance of blood. The calibre
of the duct usually decreases as it ascends through the thorax, but increases again
at its upper part. It is least at or about the fifth thoracic vertebra. The thoracic
duct conveys the lymph from the lower extremities, the lymph and chyle from the
abdomen (except some of the lymph from the convex surface of the liver), the lymph
from the left side of the thorax, and some of that from the right side, and the
lymph from the left upper extremity and the left side of the head and neck.
The relations of the thoracic duct in the abdomen, the thorax, and at the root
of the neck, may be considered separately.
1. The abdominal portion of the thoracic duct lies deeply placed behind and
between the aorta and the right crus of the diaphragm on the front of the body of
the second lumbar vertebra. This part of the duct is dilated into an irregular,
sacculated, and fusiform sac, known as the receptaculum chyli, or cistern of Pecquet.
It receives the efferent vessels of the lumbar glands, the intestinal lymphatic trunk,
and sometimes some of the hepatic and gastric lymphatics. It is thin-walled and
contains no valves, and is about an inch and a half long (38 mm.) and about a quarter
of an inch in diameter at its widest part (7 mm.). As the duct passes through the
aortic opening of the diaphragm, it still lies to the right of the aorta, and has the
vena azygos major to its right side.
2. The thoracic portion of the thoracic duct lies at first in the posterior
mediastinum between the aorta and the vena azygos major, in front of the seven
lower thoracic vertebræ ; but at the level of the fifth thoracic vertebra it passes to the
left behind the oesophagus and aortic arch, and enters the superior mediastinum,
whence it escapes through the upper aperture of the thorax into the root of the
neck.
In the posterior mediastinum it has in front of it, from below upwards, the
pericardium, the oesophagus, and the arch of the aorta; behind it, the seven lower

THORACIC DUCT
699
thoracic vertebræ, the anterior common ligament, the lower right intercostal arteries,
the vena azygos minor, and at times one or more of the mid left intercostal veins,
and the vena azygos tertia. To its left is the thoracic aorta, and to its right the
vena azygos major and the right pleura. In the superior mediastinum it ascends,
between the œsophagus and left pleura, to the posterior and left side of the superior
thoracic opening. It here has in front of it the first portion of the left subclavian
artery, behind it the upper thoracic vertebræ, to its left the pleura, and to its right
the œsophagus.
Opening into the thoracic portion of the duct are:-the lymphatics from the
left half of the thoracic walls; the efferent vessels from the left anterior mediastinal
and intercostal glands; the lymphatics of the left lung and the left side of the
heart; the lymphatics of the trachea and oesophagus, and the right lower internal
mammary lymphatics.
3. The cervical portion of the thoracic duct ascends as high as the level of the
seventh cervical vertebra, and then curves, downwards and forwards, over the apex
of the pleura in front of the subclavian artery, scalenus anticus muscle, and vertebral
vein, behind the left internal jugular vein, and behind and subsequently external to
the left common carotid artery, and, having received the left jugular lymphatic
trunk, opens into the left innominate vein at the confluence of the internal jugular
and subclavian veins. The cervical portion receives the lymphatics from the left
upper extremity and left side of the head and neck.
The chief variations in the thoracic duct.-(1) The thoracic duct may be double; when
this is the case, the left duct may end normally in the left innominate vein, and the right
in the corresponding situation on the right side; or the two ducts may unite at the root of
the neck, and open into the left innominate vein. (2) The reduplication may be incom-
plete. Thus: (a) The duct may at first be single, but divide into two separate vessels at a
variable distance from its termination, and then (i) one branch of the duct may enter
the left confluence of veins at the root of the neck; the other the right confluence, a normal
condition in some animals; or one may enter the confluence of veins in the normal
manner, the other either the subclavian or internal jugular vein; or (ii) the two branches
may reunite-this is a frequent variety, and is regarded as a normal condition by some
anatomists. (b) It may break up into several branches in its course through the thorax,
forming a plexus of vessels, which subsequently reunite into a single duct. (3) The
thoracic duct may lie altogether to the left side of the aorta, and terminate as normal.
(4) The duct may open into the confluence of the subclavian and internal jugular veins on
the right side, an abnormal arrangement which may occur under the following condi-
tions: (a) when the viscera are transposed; (b) when there is a right aortic arch without
transposition of viscera; and (c) when the vessels and viscera are normal. (5) The duct
may end in the vena azygos major.


THE LYMPHATICS OF THE ABDOMEN AND PELVIS
The lymphatics of the abdomen and pelvis may be divided into the parietal,
which ramify in the abdominal and pelvic walls; and the visceral, which receive
the lymph from the pelvic viscera, and the lymph and chyle from the abdominal
viscera.

I. THE PARIETAL LYMPHATIC VESSELS AND GLANDS
OF THE ABDOMEN AND PELVIS
1. The parietal lymphatic vessels may be subdivided into the superficial,
which ramify beneath the skin in the subcutaneous tissue, and include the
lymphatics of the skin of the penis and scrotum and of the external genital
700
THE LYMPHATICS
organs in the female; and into the deep, which accompany the deep arteries of the
abdominal and pelvic walls. The former for the most part end in the superficial
inguinal glands; the latter in the lumbar glands.
(1) The superficial parietal lymphatics.-The superficial parietal lymphatics
of the abdominal walls are situated between the skin and the abdominal muscles.
Those from the front of the abdomen, below the level of the umbilicus, pass
downwards along the course of the superficial epigastric artery and veins, and end
in the superficial inguinal glands. The lymphatics from the upper part of the
front of the abdomen, above the level of the umbilicus, pass upwards and outwards
with the lymphatics from the front and side of the chest to the axillary glands.
The lymphatics from the lateral abdominal walls run, in part over the crest of
the ilium, in the course of the superficial circumflex iliac artery and veins, into
the outer superficial inguinal glands, and in part follow the course of the lumbar
and ilio-lumbar arteries, and, after perforating the abdominal muscles, end in the
lateral lumbar glands. The superficial lymphatics from the lower part of the back
and from the gluteal region for the most part pass outwards over the gluteal
muscles to end in the outermost superficial inguinal glands; but those from the
region of the anus follow the course of the perinæal lymphatics through the fork to
the innermost superficial inguinal glands.
The superficial lymphatics of the penis begin in the prepuce, and thence pass
backwards to the corona glandis, where they form a ring around the glans. This
ring receives the superficial lymphatics from the glans, and the lymphatics from
the anterior two-thirds of the urethra which run from behind forwards. From
the glans three main lymphatic channels run backwards under the integuments
of the penis, one on the dorsum, and one on each side of the organ. At the root of
the penis the dorsal lymphatic vessel divides into a right and left branch, each
branch passing with the lateral lymphatic vessel of the corresponding side to the
superficial inguinal glands. The deep lymphatics of the penis pass with the dorsal
vein into the pelvis, where they join the lymphatic glands about the internal iliac
artery.
The lymphatics of the scrotum in the male, and of the parts corresponding
thereto in the female, and the lymphatics of the other external generative organs
in the female, run with the superficial external pudic arteries to the superficial
inguinal glands. It will be noted that the lymphatics of the testicle pass with the
spermatic artery to the lumbar glands.
The superficial lymphatics of the perinæum run upwards over the adductor
muscles, through the fork between the thighs, and join the superficial inguinal
glands.
(2) The deep parietal lymphatics.-The deep lymphatics of the anterior and
lateral abdominal walls accompany the parietal vessels to the back of the abdomen,
where they end in the deep glands. Thus some follow the deep epigastric artery to
the external iliac glands; others the deep circumflex iliac artery also to the external
iliac glands; and others, again, the ilio-lumbar and lumbar arteries to the lateral
lumbar glands. The last are also joined by the lymphatics from the muscles of
the back and from the spinal cord. The deep lymphatics from the upper part of
the abdominal wall pass, with the superior epigastric artery, into the thorax, where
they end in the internal mammary lymphatic glands.
The deep lymphatics of the pelvic walls accompany the parietal vessels, and
hence are found with the obturator, sciatic, gluteal, pudic, and sacral arteries.
They end in the glands surrounding the internal iliac artery, and in the sacral
glands.
2. The parietal lymphatic glands lie, for the most part, along the back of the
abdomen and pelvis, and are known, from their position, as the external iliac, internal
iliac, sacral, lumbar, and coeliac glands.


LYMPHATICS OF ABDOMEN AND PELVIS
701
The external iliac lymphatic glands lie along the course of the external iliac
and common iliac arteries and veins. They are three to five or more in number.
They receive the lymphatics from the inguinal glands and femoral glands, and
the deep lymphatic vessels accompanying the deep epigastric and deep circum-
flex iliac arteries and veins from the anterior and lower abdominal walls. Their
efferent vessels join the lumbar glands. They communicate with the internal iliac
glands.
The internal iliac glands are situated in the course of the internal iliac artery
and its branches. They vary from nine to twelve or more in number, the largest
being situated at the upper part of the great sciatic foramen. They receive the
lymphatics from the muscles of the pelvis and the lymphatics corresponding to the
branches of the internal iliac artery. Thus the greater number of the lymphatics
from the pelvic viscera, from the deeper parts of the perinæum, and from the
hinder and deeper parts of the scrotum or labia majora, the deep lymphatics of the
penis and posterior part of the urethra, the deep lymphatics from the gluteal
region, and some of the lymphatics from the adductor muscles of the upper part
of the thigh, join these glands. Their efferent vessels pass to the lumbar glands.
The sacral glands are situated in the hollow of the sacrum, four or five
being placed in the meso-rectal folds opposite its promontory. They receive the
lymphatics from the rectum and the hinder walls of the pelvis. They join the
lumbar glands.
The lumbar glands lie beneath the peritoneum, at the back of the abdomen, on
the front and sides of the lumbar vertebræ. They are usually divided into three
groups, a median and two lateral; but these freely communicate with each other
across the aorta and vena cava.
The median group (aortic lumbar glands) consists of about six large glands
placed along the abdominal aorta and vena cava. They extend from the bifurcation
of the aorta to the second lumbar vertebra.
The median group receive the efferent vessels of the external and internal iliac
and sacral glands, the lymphatics accompanying the spermatic or ovarian vessels
from the testicle or ovarian plexus respectively, and the lymphatics of the kidneys,
suprarenal bodies, and hinder portion of the diaphragm. They also receive most
of the efferent vessels from the lateral sets. Their efferent vessels commonly unite
about the level of the second lumbar vertebra to form a right and a left lumbar
lymphatic trunk, which open, with some small vessels from the lateral sets, into the
receptaculum chyli. The left lumbar trunk also receives the lymphatics of the
descending colon and sigmoid flexure.
The lateral lumbar glands, transverse lumbar or psoas glands, are situated
behind the psoas between the transverse processes of the lumbar vertebræ. They
are twenty or thirty in number, and smaller than the glands of the central group.
The lateral glands receive the lymphatics accompanying the lumbar arteries,
the lymphatics from the muscles of the back, the spinal canal, and from the deeper
parts of the parietes of the posterior abdominal walls. Their efferent vessels open,
in part into the median set, and in part, as separate vessels, into the receptaculum
chyli.
The coeliac glands, sixteen to twenty in number, are grouped around the cœliac
axis in front of the aorta, above the origin of the superior mesenteric artery. At
the back of the transverse meso-colon they receive the efferent vessels from
some of the hepatic glands, the superior gastric glands, the inferior gastric glands,
the splenic and the pancreatic glands. Their efferent vessels join the intestinal
lymphatic trunk, and open into the receptaculum chyli.


702
THE LYMPHATICS
II. THE VISCERAL LYMPHATIC VESSELS AND GLANDS
OF THE ABDOMEN AND PELVIS
The lymphatics of the pelvic and abdominal viscera are considered separately.
1. The lymphatics of the pelvic viscera.-The lymphatics of the bladder pass
partly backwards, beneath the peritoneum, to join the rectal lymphatics, or the
lymphatics of the uterus and vagina in the female; and partly forwards, to join the
prostatic lymphatics and the lymphatics of the vesiculæ seminales. These anterior
sets of lymphatics, together with those from the prostate and vesiculæ seminales,
pass through the anterior true ligaments of the bladder, in which there is a small
gland, into the internal iliac lymphatics.
The lymphatics of the rectum run backwards between the two layers of the
meso-rectum, in which there are four or five glands, through the sacral to the
lumbar glands.
The lymphatics of the uterus, vagina, ovaries, and Fallopian tubes.-The
superficial lymphatics of the uterus, which lie beneath the peritoneum, pass,
together with those of the substance of the fundus and upper part of the body of
the organ, outwards, in the broad ligament, where they join the lymphatics from the
ovaries and Fallopian tubes, and pass up, with the ovarian vessels, to the lumbar
glands. The lymphatics from the lower part of the body and from the cervix of
the uterus run, together with most of the lymphatics of the vagina, along the
course of the uterine and vaginal vessels, and terminate in the internal iliac glands.
The lymphatics from the lower part of the vagina join the superficial inguinal
glands.
The lymphatics of the testicle accompany the spermatic vessels, and terminate
in the lumbar glands. Hence in carcinoma of the testicle the lumbar glands are
those which first become enlarged, the inguinal not being affected until the skin of
the scrotum becomes involved in the disease.
2. The lymphatics of the abdominal viscera are divided into-(1) The
lymphatics of the stomach; (2) the intestines; (3) the liver; (4) the spleen; (5)
the pancreas; (6) the kidneys; (7) the ureters; and (8) the suprarenal capsules.
(1) The lymphatics of the stomach begin in the mucous and subserous coat, and
thence follow the course of the blood-vessels. Thus some run upwards to the
lesser curve of the stomach, others downwards to the greater curve, and others left-
wards to the greater end. In this way, three chief sets are formed-the superior
gastric, the inferior gastric, and the left gastric lymphatics. (a) The superior
gastric follow the course of the coronary vein along the lesser curvature towards the
cardiac end of the stomach, lying between the layers of the lesser omentum. They
pass on their way through five or six small (superior gastric) lymphatic glands.
Reaching the cardia, they turn downwards, and, having been joined by some of
the lymphatics from the left lobe of the liver, enter the upper cœliac glands.
(b) The inferior gastric lymphatics follow the course of the right gastro-epiploic
vessels towards the pylorus, along the greater curvature of the stomach, between
the layers of the greater omentum. After passing through six or eight small glands
(inferior gastric), they are joined by the lymphatics from the upper part of the
duodenum, and run between the pylorus and pancreas to the coeliac glands. (c) The
left gastric lymphatics run with the vasa brevia, between the folds of the gastro-
splenic omentum, to the splenic lymphatic glands.
The lymphatic glands of the stomach are the superior and inferior gastric
glands.
The superior gastric glands, five or six in number, are situated along the
lesser curve between the layers of the gastro-hepatic omentum. They receive the
LYMPHATICS OF ABDOMEN AND PELVIS
703
superior gastric lymphatics; their efferent ducts pass, first upwards towards the
œsophagus, and then, after receiving the lymphatics from the upper and left portion
of the left lobe of the liver, turn downwards behind the pancreas to join the cœliac
glands.
The inferior gastric or gastro-epiploic glands, six or eight in number, lie along
the greater curve of the stomach between the layers of the great omentum. They
receive the inferior gastric lymphatics and the lymphatics of the great omentum.
Their efferent vessels pass with the lymphatics from the upper part of the duo-
denum into the cœliac glands.
(2) The lymphatic vessels of the intestines are divided into the lymphatics of the
small intestine and the lymphatics of the large intestine.
The lymphatics of the small intestines are called the lacteals, because they
carry the chyle as well as the lymph from the intestinal walls. Beginning partly
beneath the peritoneal coat-but chiefly in two plexuses, one between the muscular
coats, and one beneath the mucous membrane-they pass round the intestine with
the blood-vessels to the mesenteric attachment, and thence between the layers of
the mesentery to the mesenteric glands.
The lymphatics of the large intestine are disposed of as follows:-(a) Those
from the cæcum and ascending colon pass between the layers of the meso-colon to
the meso-colic glands. (b) Those from the transverse colon and upper half of the
descending colon pass with the middle colic artery between the layers of the meso-
colon, also to the meso-colic glands. (c) Those from the lower half of the descend-
ing colon and sigmoid flexure pass into the left lymphatic trunk of the lumbar
glands. The lymphatics of the rectum are described with the lymphatics of the
pelvis (page 702).
The lymphatic glands of the intestines are the mesenteric and meso-colic.
The mesenteric glands, some one hundred and fifty to two hundred in number,
lie between the layers of the mesentery. They are arranged roughly in three sets:
(a) A primary set, about two inches from the intestinal margin of the mesentery.
receive the lymphatics from the intestine. The efferent vessels from these glands
pass into the next or secondary set. (b) The secondary set are situated about the
primary loops of the superior mesenteric artery; they are more numerous than the
primary set, and receive the efferent vessels of the latter. Their efferent vessels
end in the tertiary set. (c) The tertiary set of glands lie along the course of
the trunk of the superior mesenteric artery. They are larger than the secondary
set, and closer together. Their efferent vessels unite to form three or four trunks,
or perhaps more often a single trunk (the intestinal lymphatic trunk) which, after
receiving the efferent vessels from the meso-colic glands, opens, either separately,
or together with the efferent ducts of the cœliac glands, into the receptaculum chyli.
The glands and lacteals of the jejunum are more numerous than those of the
ileum.
The meso-colic glands, twenty to thirty in number, are placed between the
layers of the meso-colon. They receive the lymphatics from the cæcum, ascending
and transverse colon, and from part of the descending colon. Their efferent vessels
join the efferent vessels from the tertiary set of mesenteric glands, and open with
them into the receptaculum chyli.
(3) The lymphatics of the liver consist of a superficial and deep set. The
former are arranged in a plexus beneath the peritoneal covering; the latter accom-
pany the blood-vessels in the substance of the organ.
(a) The superficial set of lymphatics form groups, and run in various directions.
Those on the upper or convex surface of the liver are disposed of as follows:-(i) The
lymphatics of the left half of the right lobe, and of the right half of the left
lobe, converge towards the falciform ligament, up which they run to the diaphragm.
They then pass through the costo-xiphoid space, and enter the anterior mediastinal

704
THE LYMPHATICS
chain of glands, and thus open in part into the right lymphatic duct.
(ii) The
lymphatics on the anterior part of the convex surface pass over the anterior margin,
and along the course of the longitudinal fissure to the hepatic glands in the gastro-
hepatic omentum. (iii) The lymphatics along the posterior margin of the liver pass
between the layers of the coronary ligament to the diaphragm, which they perforate,
and end in small glands about the upper part of the vena cava (Quain). (iv) A
group from the right half of the right lobe pass outwards and backwards to the right
lateral ligament, where they either perforate the diaphragm and end in the anterior
mediastinal glands, or cross its crus and open into the coeliac glands or receptaculum
chyli. (v) A group from the left half of the left lobe pass through the left lateral
ligament, and join the œsophageal lymphatics at the oesophageal opening of the
diaphragm, or pass with the superior gastric lymphatics behind the pancreas to
the cœliac glands. Or they may pierce the diaphragm and enter the glands in the
anterior mediastinum.
-
The superficial lymphatics on the under surface of the liver are arranged as
follows: (i) The greater number converge to the transverse fissure, and thence
pass with the deep lymphatics to the hepatic glands in the gastro-hepatic omentum;
(ii) a group from the back of the right lobe pass to the lumbar glands; (iii) a group
from the back of the left lobe join the oesophageal lymphatics or superior gastric
lymphatics, and end with them in the cœliac glands; (iv) the lymphatics of the
gall-bladder run with the hepatic artery to the hepatic glands in the gastro-hepatic
omentum.
(b) The deep set of lymphatics run, in part with the portal vein, and in part
with the hepatic vein. (i) The portal set emerge at the transverse fissure, and
pass with the blood-vessels to the hepatic glands in the gastro-hepatic omentum.
(ii) The hepatic set perforate the diaphragm with the inferior vena cava, and,
having passed through some small glands round the upper part of that vessel, join
the superficial lymphatics from the posterior margin of the liver, and with them.
run down the thoracic surface of the vertebral portion of the diaphragm to the
commencement of the thoracic duct or receptaculum chyli.
The hepatic glands are situated in front of the portal vein between the layers
of the gastro-hepatic omentum. They receive the deep portal set of lymphatics,
the anterior group of the superficial lymphatics from the convex surface of the
liver, most of the superficial lymphatics from the under surface of the liver, and
the lymphatics from the gall-bladder. Their efferent vessels proceed to the coeliac
glands.
(4) The lymphatics of the spleen. The splenic lymphatics are arranged in a
superficial set which ramify beneath the peritoneal covering; and in a deep set,
which run with the vessels in the parenchyma of the organ. Both sets unite at
the hilum, and terminate in the splenic glands.
The splenic glands, eight to ten in number, are situated in the hilum of the
spleen, and along the course of the splenic artery and vein. They receive the
superficial and deep lymphatics of the spleen, and the left gastric lymphatics which
run with the vasa brevia in the gastro-splenic omentum from the greater end of
the stomach. The efferent vessels run behind the peritoneum and pancreas with
the splenic artery to the coeliac glands. They are joined on the way by the
lymphatics of the pancreas.
(5) The lymphatics of the pancreas consist of a double set, a superficial and a
deep. They leave the pancreas along with the vessels derived from the splenic
artery, and, joining the lymphatics of the spleen, end in the cœliac glands.
(6) The lymphatics of the kidneys ramify, partly on the surface, and partly in the
substance of the organ. They unite at the hilum, and run inwards to the central set
of lumbar glands. They receive the lymphatics from the suprarenal bodies and
from the upper part of the ureters.

LYMPHATICS OF LOWER EXTREMITY
705
(7) The lymphatics of the ureters end chiefly in the renal lymphatics. Those
from the lower part join the posterior vesical set of lymphatics.
(8) The suprarenal lymphatics leave the suprarenal bodies with the suprarenal
veins, and join for the most part the renal lymphatics in the hilum of the kidneys.
A few pass direct into the central lumbar chain of glands.
THE LYMPHATICS OF THE LOWER EXTREMITY
The lymphatics of the lower extremity, like those of the upper, may be divided
into the superficial and the deep. The former run in the subcutaneous tissue with
the superficial veins, the latter along the course of the deep arteries. At the groin
the superficial end in the deep, which then pass under Poupart's ligament into the
abdomen.
I. THE SUPERFICIAL LYMPHATIC VESSELS AND GLANDS
OF THE LOWER EXTREMITY
The superficial lymphatic vessels follow in chief part the long and short
saphenous veins. Passing from the toes to a plexus on the dorsum and sole of the
foot respectively, they thence run up the leg, forming two chief sets of lymphatic
vessels, an inner and an outer. The inner and larger accompanies the long
saphenous vein in front of the ankle, behind the inner side of the knee, and then up
the inner and front part of the thigh to the inguinal glands. The outer set,
beginning on the outer side of the foot, run up the outer side of the leg, some
passing round the front of the tibia to end in the inner set below the knee; others
passing over the popliteal space to join the inner set higher in the limb; and
others, again, perforating the deep fascia along with the short saphenous vein to
end in the popliteal glands.
The lymphatics of the gluteal region wind, in part round the inner side of the
thigh, over the upper portion of the adductors, to join the innermost inguinal glands;
and in part over the crest of the ilium to join the outermost inguinal glands.
The superficial lymphatic glands.-There are no superficial glands below the
inguinal.
The inguinal glands, six to twelve in number, are situated in the inguinal
region. They may be subdivided into the oblique, or inguinal proper, which are
grouped along the course of Poupart's ligament; and the vertical, or femoral, or
saphenous, which surround the saphenous opening.
The oblique or inguinal glands proper, which are situated on a higher level
than the vertical set, receive the lymphatics from the integuments of the penis and
scrotum, and the skin of the pudenda and lower part of the vagina in the female.
They also receive the lymphatics from the integuments of the lower part of the
abdomen, and that covering the perinæal and gluteal regions. Their efferent vessels
in part pass through the saphenous opening, and in part perforate the deep fascia
to end in the deep inguinal and, to some extent, in the lumbar glands. It is these
superficial inguinal glands which become enlarged in venereal disease, in chancres
and epithelioma of the penis and scrotum, or labia in the female, and in boils or
other sources of irritation about the anus, gluteal region, and perinæum.
The vertical set, or saphenous or superficial femoral glands, receive the super-
ficial lymphatics from the lower limb. They are found enlarged in sores on the
heel, malignant disease of the skin, etc.


Z Z

706
THE LYMPHATICS
FIG. 400.-THE SUPERFICIAL LYMPHATICS OF THE LOWER LIMB.
Superficial epigastric vein
Superficial lymphatics
from lateral wall of
abdomen
Superficial lymphatics
from lower and anterior
walls of abdomen
Lymphatics from penis
and scrotum
Dal Common femoral vein
Superficial femoral
lymphatic glands
Superficial external pudic
vein
Superficial inguinal
lymphatic glands
Superficial circumflex
iliac vein
Internal femoral cutaneous
vein
External femoral
cutaneous vein
Long saphenous vein
INTERNAL MALLEOLUS
Dorsal venous arch
LYMPHATICS OF LOWER EXTREMITY
707
II. THE DEEP LYMPHATIC VESSELS AND GLANDS
OF THE LOWER EXTREMITY
The deep lymphatic vessels of the lower limb follow the course of the deep
arteries and veins. Thus they accompany the internal and external plantar arteries
in the sole, and the dorsalis pedis artery on the dorsum of the foot. In the leg
they are found following the posterior tibial, anterior tibial, and peroneal arteries,
and, after passing through the lymphatic glands in the popliteal space, accompany,
first, the popliteal, and then the femoral artery up the thigh to the deep inguinal
or deep femoral glands. Deep lymphatics also run with the profunda artery. These
also join the deep femoral lymphatic glands. Others accompany the gluteal and
ischiatic artery, and end in the lymphatic glands of the same name at the great
sciatic foramen.
The deep lymphatic glands of the lower extremity are met with chiefly in the
popliteal space and in the inguinal region. One, or sometimes two, small glands,
however, may be found in the upper part of the front of the leg, lying on the inter-
osseous membrane along the course of the anterior tibial artery.
The popliteal glands are placed deep in the popliteal space around the popliteal
artery and vein. They receive the deep lymphatics from the leg, and those of the
superficial which perforate the deep fascia along with the external saphenous
vein. Their efferent vessels accompany the popliteal and the femoral vessels to
the deep inguinal or femoral glands.
The deep inguinal or deep femoral glands surround the upper part of the
femoral vessels. One or more are constantly found in the femoral canal. They
receive the deep lymphatics accompanying the femoral artery, and a few of the
efferent vessels from the superficial inguinal glands. Their efferent vessels pass, in
part along the course of the femoral vessels, and in part through the femoral ring
to join the glands along the course of the external iliac artery.

ZZ2
SECTION V.
THE NERVOUS SYSTEM
By H. ST. JOHN BROOKS, M.D., B.CH., D.Sc., B.A.
UNIVERSITY ANATOMIST AND EXAMINER IN ANATOMY IN THE UNIVERSITY OF DUBLIN; SURGEON TO
SIR PATRICK DUN'S HOSPITAL.
NE
NEUROLOGY
cerebrospinal
EUROLOGY is that branch of Anatomy which deals with the nervous system.
It treats of the brain and spinal cord, constituting the cerebro-spinal axis or
central nervous system; and the cranial and spinal nerves, or peripheral
nervous system. The sympathetic system is to be regarded as an appendage of
the latter, although, as has been recently shown, there is reason to believe that
it originates independently. The study of the nervous system (of the brain in
particular) is greatly facilitated by a knowledge of its mode of development and by

FIG. 401.-DIAGRAMMATIC SAGITTAL SECTION OF A VERTEBRATE BRAIN. (After Huxley.)
CORPORA QUADRIGEMINA
MESENCEPHALON
PINEAL BODY
CEREBELLUM-
4
MEDULLA
OBLONGATA
PONS VAROLII-
S
CRURA CEREBRI
OPTIC
THALAMUS
LATERAL
VENTRICLE
CEREBRAL
HEMISPHERE
CORPUS
STRIATUM
CEPHALON
RHINEN-
PITUITARY
BODY
FORAMEN OF MONRO
THALAMENCEPHALON
4, fourth ventricle; s, aqueduct of Sylvius; 3, third ventricle.
Comparative Anatomy. It is not our purpose to enter into these subjects here; but
an examination of the two diagrams (figs. 401, 402), which are based upon
Embryology and Comparative Anatomy, will familiarise the student with the plan
upon which the brain is laid down, and form a key to the complicated structure of
the adult human brain.
At an early period of embryonic life the cerebro-spinal axis consists simply of
a thin walled tube, the neural tube, which becomes enlarged at the cephalic end of
the body. Constrictions appear on this enlarged cephalic end, dividing it into three
vesicles, an anterior, a middle, and a posterior. The ventricles of the brain are

KT NEUROLOGY
709

afterwards developed from these three cerebral vesicles, and the remainder of the
neural tube forms the central canal of the spinal cord. The substance of the brain
and cord is formed by thickenings of the wall of this neural tube. The terminal
or anterior cerebral vesicle becomes divided into an anterior and a posterior division;
the latter persists as the third ventricle, which, with the parts around it, constitutes
the thalamencephalon. The anterior division is afterwards differentiated into the
cerebral hemispheres or prosencephalon. It becomes at first indented in the
middle line, and then completely bilobed. In this way two symmetrical cavities,
the right and left lateral ventricles, are formed.
The anterior part of the wall of the cerebral vesicle between the two hemi-
spheres, thus mapped out, is called the lamina terminalis. The lamina terminalis
is carried backwards so as to bound the third ventricle in front, and the aperture of
communication (foramen commune anterius), connecting the third with the lateral
ventricles, becomes narrowed. The cavity of the middle cerebral vesicle becomes
the aqueduct of Sylvius, and the parts developed around it constitute the mid-brain
or mesencephalon. The cavity of the posterior cerebral vesicle becomes the fourth
ventricle, and its walls are differentiated into the cerebellum and pons Varolii
(epencephalon), and into the medulla oblongata (metencephalon).

FIG. 402.-DIAGRAMMATIC HORIZONTAL SECTION OF A VERTEBRATE BRAIN.
(After Huxley.)

EPENCEPHALON
OPTIC THALAMUS
A MEDULLA.
OBLONGATA
4
3
CEREBELLUM
MESENCEPHALON PINEAL FORAMEN OF MONRO
BODY
LATERAL
VENTRICLE
RHINEN
CEPHALON
LAMINA
TERMINALIS
-CORPUS
STRIATUM
The walls of the lateral ventricles become greatly thickened and form the
cerebral hemispheres, constituting the greater part of the mass of the brain. They
grow backwards from the position represented in the diagram (fig. 401), and cover
the mid- and hind-brain. In front of the lamina terminalis the walls of the lateral
ventricles remain thin, and approximate so as to enclose a narrow space, the fifth
ventricle. Thus the fifth ventricle differs entirely in its nature from the other
ventricles of the brain: it is a separated portion of the interhemispheric or great
longitudinal fissure, and has nothing to do with the true ventricular cavities; accord-
ing to Testut it is lined by a rudimentary layer of pia mater. Later on, a great
transverse commissure (corpus callosum), which passes from one hemisphere to the
other, is developed. It commences in front of the fifth ventricle in the secondarily
fused portions of the cerebral walls, and afterwards extends backwards as the
hemispheres grow over the mesencephalon.
The oldest portion of the cerebral hemisphere, both in the series of vertebrates
and in the development of the individual, is the island of Reil with the grey
masses which lie subjacent to it (nucleus caudatus and nucleus lenticularis of the
corpus striatum). These structures constitute a central portion (Stammtheil of
Schwalbe) which is almost completely invested by the remaining larger part of the
hemisphere. The latter forms the less massive part of the wall of the lateral
ventricle, and may be called the mantle-wall (Manteltheil of Schwalbe).

710
THE NERVOUS SYSTEM
The ventricular cavities of the brain and the central canal of the spinal cord are
lined by a layer of ciliated epithelial cells, immediately outside which is a stratum
of neuroglia, free from nerve-cells, which is called ependyma. The ependyma
around the central canal of the cord is often termed substantia gelatinosa centralis.
Neuroglia is the name given to the peculiar interstitial tissue of the brain and cord.
It is continuous with processes of pia mater which dip in from the surface.
Nerve-fibres are processes or outgrowths of the nerve-cells of the central
nervous system, from which they pass to be distributed to every part of the body.
They are classed by physiologists into efferent and afferent fibres. Efferent or
centrifugal nerve-fibres convey impulses from the nerve-centres; they comprise
motor nerves to muscles, secreto-motor nerves to glands and vaso-motor nerves.
Afferent or centripetal nerves convey impulses towards the nerve-centres; they
comprise sensory nerves and other nerves conveying impulses, which under ordinary
circumstances do not produce conscious sensations. Nerve-fibres run for the
greater part of their course in compact bundles of various sizes, and these bundles
are called nerves in the most general use of the term. Nerves are usually mixed
(i.e. contain both efferent and afferent fibres). Most nerves are of a whitish colour
owing to a medullary sheath which invests the essential parts (axis-cylinders) of
the individual fibres. Others (chiefly visceral nerves) are of a pearly-grey colour
owing to the absence of the medullary sheath in the majority of the fibres which
make up the nerve.
The fibres of sensory nerves are outgrowths from nerve-cells contained in ganglia,
such as the Gasserian ganglion and the ganglia on the posterior roots of the spinal nerves.
These ganglia, although appearing to belong to the peripheral nervous system in the adult,
were (in early embryonic life) in continuity with the general epiblast of the neural canal.
Certain terms which are in frequent use, such as coronal, sagittal, and hori-
zontal, may be defined here. A coronal section is a vertical section passing
through or parallel to the coronal suture, in other words, a transverse vertical
section. A sagittal section is a vertical section taken at right angles to a coronal
section-an antero-posterior vertical section. A horizontal section is a section taken
at right angles to the perpendicular axis of the body. Structures which lie in the
planes of these sections are sometimes spoken of as coronally placed, sagittally
directed, etc.
THE MENINGES
The brain and spinal cord are invested by three membranes, termed the meninges,
which afford protection and support to the delicate nervous structures, and also
furnish a convenient medium in which the blood-vessels can ramify. The outer
of these is thick and tough, and is termed the dura mater. The intermediate and
inner membranes (arachnoid and pia mater) are thin and delicate. These mem-
branes present differences in the regions of the brain and spinal cord respectively.
The membranes of the brain will be first considered, and the differences met with
in relation to the spinal cord will be dealt with in the description of that region.
Dissection. The first step in the examination of the meninges is the removal of the
brain. The calvaria should be removed as follows:-The bone having been laid bare, a
string should be tied round the skull passing from about an inch and a quarter above the
external occipital protuberance behind, to an inch above the orbital arches in front. The
outer table of the skull should then be sawn through and the inner table afterwards cracked
with the mallet and chisel. A slight wrench will now disengage the calvaria. After
noticing the Pacchionian bodies and the meningeal arteries, the student will do well to

MENINGES
711
examine the superior longitudinal sinus by laying it open. He should next cut through
the dura mater in an antero-posterior direction on each side of the sinus, and then make
incisions directed transversely outwards from the central points of the two previous
incisions as far as the cut margin of the bone. The four triangular flaps thus mapped out
should be turned downwards, and by gently drawing one of the hemispheres aside, the falx
cerebri may be seen in situ within the great longitudinal fissure, and the veins entering
the superior longitudinal sinus may be noted. The falx should then be divided close to its
attachment to the crista galli and thrown backwards. The head should next be inclined
backwards and the frontal lobes of the brain gently raised. The following structures will
then come into view, viz. the olfactory bulbs, the second, third, and fourth nerves, the
infundibulum, and the internal carotid arteries. The olfactory bulbs will come away with
the brain, but the other structures will require to be divided with scissors, as the nerves
are frequently torn away from their connections by using a scalpel for this purpose. The
head should next be gently inclined towards the right side, and the tentorium divided close
to its attachment to the bone. The sixth, seventh, and eighth nerves should be cut at the
same time. This dissection should be repeated on the opposite side. The head should
then be tilted backwards, and the remaining cranial nerves, the vertebral arteries, and the
commencement of the spinal cord cut through. The latter should be divided as low down
as it can be reached with the scalpel. The brain can now be removed from the cranial
cavity, the veins of Galen being ruptured by this process.

The DURA MATER is a tough fibrous membrane of a bluish-white colour present-
ing externally a rough appearance, but internally smooth and shining. It performs
the double function of a periosteum to the interior of the skull and of affording
support and protection to the brain. In correspondence with this double function it
may be regarded as consisting of two layers, an outer or periosteal lamina, and an
inner or supporting lamina. These layers are inseparable for the greater part of
their extent, but along certain lines the inner lamina leaves the periosteal lamina and
forms shelf-like projections (of which the falx cerebri and the tentorium cerebelli
are examples) into the cranial cavity. Along the lines where these layers divaricate
spaces occur which form cranial sinuses. A cranial sinus may be defined as a space
formed by the cleavage of the dura mater, lined by a prolongation of the lining
membrane of a vein and conveying venous blood. Some of the sinuses are placed
between the periosteal and supporting layers of the dura mater-the lateral sinus is
a good example of this class. Others (as the straight sinus) are bounded wholly by
the inner or supporting layer.
The cranial sinuses form two principal systems, which, however, communicate with one
another. The following is a list of the sinuses which unite to form the larger of these
two systems:-superior longitudinal, inferior longitudinal, straight, occipital, superior petrosal.
These form a system which converges at the torcular Herophili, a dilated blood-space situated
on the right side (rarely on the left) of the internal occipital protuberance. The blood
from the torcular is drained away by the lateral sinuses (more particularly by the right
sinus), and leaves the cranium through the posterior compartment of the jugular foramen.
The straight sinus usually passes into the left lateral sinus. The smaller system comprises
the spheno-parietal, cavernous, circular, transverse, and inferior petrosal sinuses. The blood
from this system passes into the internal jugular vein through the anterior compartment
of the jugular foramen. A portion of the blood conveyed by the cavernous sinus, however,
passes into the lateral sinus through the superior petrosal sinus.
Emissary veins.-These veins are possibly extracranial tributaries of the cranial sinuses
under normal conditions, but, in cases of engorgement of the sinuses, permit the flow of
blood in the opposite direction, and become, in accordance with their name, emissary.
The mastoid emissary is the most important of these veins; it passes through the mastoid
foramen to enter the lateral sinus, and explains the value of applying leeches behind the
ears in cases of cerebral congestion. Two small emissaries enter the superior longitudinal
sinus, one of these passes through the foramen cæcum; another traverses the parietal
foramen. An additional vein occasionally passes to the torcular Herophili through a
foramen in the occipital bone near the external occipital protuberance. Emissary veins pass
through the foramen ovale and foramen of Vesalius, and place the cavernous sinus in com-
munication with the pterygoid venous plexus; others traverse the cartilage which occupies
the foramen lacerum medium. Small veins enter the lateral sinuses through the anterior
and posterior condyloid foramina. A minute venous plexus, which accompanies the
internal carotid artery through the carotid canal, establishes a communication between the
cavernous sinus and the internal jugular vein. (Rektorzik.)


712
THE NERVOUS SYSTEM
The dura mater of the brain is continuous through the foramen magnum with
the dura mater of the cord. It is also continuous, through the various foramina
in the cranium, with the external periosteum of the skull. This is most easily
observed at the sphenoidal fissure, but may be made out with ordinary care at any
of the other foramina. It sends a strong prolongation through the optic foramen
which splits into two layers, one of which forms the sheath of the optic nerve, and
the other is continued into the periosteum of the orbit. On account of the number
of foramina at the base of the skull, it follows that the dura mater is more firmly
connected to the bone here than at the roof and sides. In the region of the basilar
process of the occipital bone, the dura mater splits into supporting and periosteal
layers. The supporting layer passes through the foramen magnum to become
continuous with the dura mater of the spinal cord. The periosteal layer clothes
FIG. 403.-CORONAL SECTION OF THE HEAD PASSING THROUGH THE MASTOID PROCESS.
(From a mounted specimen in the Anatomical Department of Trinity College, Dublin.)

Superior longi-
tudinal sinus
CORPUS
CALLOSUM
Choroid plexus
Veins of Galen
Tentorium,
cerebelli
Lateral sinus-
CORPUS
DENTATUM
-Falx cerebri
CAUDATE
NUCLEUS
LATERAL
VENTRICLE.
Superior petrosal
sinus
MASTOID ANTRUM
Lateral sinus
MASTOID PROCESS

the bone and is thickened into a ligamentous band, the occipito-cervical or cervico-
basilar ligament (page 198), which passes through the foramen magnum to join the
posterior common ligament of the vertebræ and to gain attachment to the body of the
axis. Thus a connection is established between the dura mater and the periosteum
of the vertebræ. At the back and sides of the foramen magnum the dura mater does
not split into periosteal and supporting layers until it reaches the margin of that
opening, where its layers divaricate, the one to become continuous with the external
periosteum of the skull, the other to be continued into the spinal dura mater. In
the middle fossa of the skull there is a separation of the periosteal and supporting
layers to form the cavernous sinus; on the inner side of this the supporting layer
is moulded round the pituitary body and then folds on itself to form the diaphragma
sellæ. External to the cavernous sinus the two layers remain separate for some
distance, forming a space (Meckel's space), which encloses the Gasserian ganglion.
The outer surface of the dura mater is covered with a number of arteries, which
ramify between it and the inner table of the skull. These vessels break up into

MENINGES
713
small twigs which penetrate the bone. The term meningeal, applied to these
arteries, is somewhat misleading, inasmuch as they do not supply any of the
meninges, except the dura mater, being chiefly destined for the nutrition of the
cranial bones. These small vessels, together with a number of fibrous retinacula,
are torn across when the dura mater is forcibly detached from the bone, and give rise
to the rough appearance which is presented by its outer surface. An examination
under water will, however, reveal smooth spots interspersed among the bundles of
ruptured vessels; these are subperiosteal lymph-spaces.
Meningeal arteries.-The middle or great meningeal artery, which enters the middle
cranial fossa through the foramen spinosum, supplies the dura mater which lines the vault
of the cranium. In addition to this there are meningeal arteries, mostly of small size,
FIG. 404.-CORONAL SECTION OF THE HEAD PASSING THROUGH THE POSTERIOR
HORNS OF THE LATERAL VENTRICLES.
(From a mounted specimen in the Anatomical Department of Trinity College, Dublin.)

Dura mater-
BULB OF
POSTERIOR
CORNU
HIPPOCAM-
PUS MINOR
FASCICU-
LUS LONGI-
TUDINALIS
INFERIOR
Superior
longitudinal
sinus
Falx cerebri
Straight
sinus
POSTERIOR
CORNU OF
LATERAL
VENTRICLE
CALCARINE
FISSURE
Lateral sinus CORPUS DENTATUM
Tentorium cerebelli
which are limited in their distribution to the base of the cranium. In the anterior cranial
fossa there are anterior meningeal branches of the anterior and posterior ethmoidal arteries,
which enter the cranium through the anterior and posterior internal orbital canals; also
twigs from the middle meningeal which usually pierce the great wing of the sphenoid
near the outer angle of the sphenoidal fissure. In the middle cranial fossa the following
arteries are met with:- a branch of the ascending pharyngeal which perforates the cartilage
which occupies the foramen lacerum medium; the meningea parva which enters the cranium
through the foramen ovale; the meningeal branch of the internal carotid, and twigs
from the middle meningeal. In the posterior cranial fossa, two meningeal branches, derived
from the occipital and ascending pharyngeal, enter through the posterior compartment
of the jugular foramen, another twig from the occipital passes through the mastoid foramen,
and a twig from the ascending pharyngeal makes its way through the anterior condyloid
foramen. A meningeal branch of the vertebral is given off from that artery, in the interval
between the occipital bone and the posterior arch of the atlas, and enters the skull through
the foramen magnum.
A branch of the occipital artery (ramus parietalis, Cruveilhier) occasionally passes through
the parietal foramen to the dura mater lining the calvaria.
The following are the infoldings formed by the inner or supporting layer of the
714
THE NERVOUS SYSTEM
dura mater, taken in their order of magnitude: the falx cerebri, the tentorium
cerebelli, the falx cerebelli, and the diaphragma sellæ. There are also two
smaller paired folds; viz. the folds which project from the lesser wings of the
sphenoid bone into the Sylvian fissures of the brain, and the crescentic folds which
are placed over the optic nerves at the upper margin of the optic foramina.
The Falx Cerebri is a large sickle-shaped process, deeper behind than in front,
which is placed in the great longitudinal fissure of the brain. It is attached by its
base to the tentorium cerebelli, in the middle line, and maintains by its tension the
vaulted character of the latter. The straight sinus follows this line of attachment.
Its apex is firmly fixed to the crista galli of the ethmoid, and has also an attach-
ment to the ethmoidal spine of the sphenoid bone. Its convex or upper margin
corresponds to the superior longitudinal sinus, and is attached to the periosteal
FIG. 405.-THE CRANIUM OPENED TO SHOW THE FALX CEREBRI, THE TENTORIUM
CEREBELLI, AND THE PLACES WHERE THE CRANIAL NERVES PIERCE THE DURA
MATER. (Sappey.)

Superior longitudinal.
sinus
Inferior longitudinal-
sinus
Veins of Galen
Falx cerebri.
Straight sinus-
Tentorium cerebelli.
Lateral sinus-
Falx cerebelli
SEVENTH AND EIGHTH
NERVES
NINTH, TENTH, AND ELEVENTH
FOURTH NERVE
THIRD NERVE
SECOND
NERVE
NERVES
TWELFTH NERVE
SECOND CERVICAL NERVE
FIRST CERVI-
CAL NERVE
Ligamentum denticulatum
FIFTH NERVE
SIXTH NERVE
layer opposite to the edges of the groove for that sinus in the frontal, the two
parietal, and the occipital bones. The inferior longitudinal sinus courses along
its concave or free margin. This margin closely approaches the corpus callosum
behind, but is separated from it by a considerable interval in front.
The Tentorium Cerebelli occupies the interval between the cerebrum and
cerebellum. It presents for examination an upper surface, a lower surface, a free
or concave border, and an attached or convex border. The upper surface is in
contact with the occipital lobes of the cerebrum, and is strongly convex upwards,
forming a roof-like structure, to the ridge of which the base of the falx cerebri is
attached. This ridge also slopes upwards and forwards, so that its highest point
is situated at the free border. The under surface is in apposition to the cerebellum.
The free border bounds an opening usually described as oval, but which is more
properly triangular with curved sides, the apex of the triangle being turned back-

MENINGES
715
wards, and corresponding to the point where the veins of Galen enter the straight
sinus. This opening transmits the crura cerebri and the superior peduncles of the
cerebellum, these parts forming an isthmus connecting the masses of brain sub-
stance above and below the tentorium; the basilar artery and the third and fourth
pairs of cranial nerves also pass upwards through this opening. Followed for-
wards, the free border is seen to be attached to the anterior clinoid processes of the
sphenoid bone. The attached border follows the lateral sinus along the occipital
and parietal bones, and then corresponds to the superior petrosal sinus along the
superior border of the petrous portion of the temporal, and finally dips under the
free border, to be attached to the posterior clinoid process of the sphenoid bone.
The Falx Cerebelli is a small prominent fold, which is placed between the
cerebellar hemispheres. Its attached border corresponds to the occipital sinus
along the internal occipital crest. Above this it is attached for a short distance to
the under surface of the tentorium. Its free border looks upwards and forwards.
FIG. 406.-CORONAL SECTION THROUGH THE GREAT LONGITUDINAL FISSURE,
SHOWING THE MENINGES. (Key and Retzius.)
SUBARACHNOID SPACE
Superior longitudinal sinus
PACCHIONIAN BODY

Dura
mater
Faix
cerebri
CORPUS CALLOSUM
The diaphragma sellæ is a small, annular, shelf-like fold of the dura mater
which roofs in the pituitary fossa, leaving a small aperture in the centre, which
transmits the infundibulum.
The subdural space is a narrow lymph-space between the dura mater and
the arachnoid. It is occupied by a small portion of the cerebro-spinal fluid, the
greater part of which, however, is lodged in the meshes of the subarachnoid tissue,
and in the ventricles of the brain (page 717). This space separates the arachnoid
from the dura mater, except where it is crossed by the veins of the brain passing
to the cranial sinuses, by the Pacchionian bodies, and by the cranial nerves at their
points of exit from the skull.
The ARACHNOID is a thin delicate membrane, which presents a well-defined
limiting surface towards the dura mater, but on its deep or pia-matral surface
passes insensibly into the subarachnoid tissue. The arachnoid does not dip into
the fissures of the cerebrum and cerebellum, with the exception of those fissures
which contain processes of dura mater. Thus it is carried into the great longitu-
dinal fissure for a depth corresponding to the falx cerebri, and it passes for a short
distance into the fissure of Sylvius around the fold of dura mater which projects
from the lesser wing of the sphenoid.


716
THE NERVOUS SYSTEM
On each side of the superior longitudinal sinus groups of small lobulated bodies,
the so-called Pacchionian glands, project from the surface of the arachnoid; these
are enlargements of the normal villi of that membrane which perforate the dura
mater and cause absorption of the bone in their vicinity. Most of these bodies are
lodged in irregular pits in the calvaria; others project into the superior longitu-
dinal sinus. They may also occur in other situations.
The subarachnoid tissue consists of very fine trabeculæ, clothed with endo-
thelial cells, which pass from the arachnoid to the pia mater. Thus, a sub-
FIG. 407.-CRANIAL NERVES IN THE BASE OF THE SKULL.
(On the left side the dura mater has been removed in the middle fossa.)
Anterior ethmoidal
artery
Posterior ethmoidal
artery
Middle meningeal artery
OPHTHALMIC
DIVISION OF FIFTH
NERVE
THIRD NERVE
Cavernous sinus
FOURTH NERVE
AUDITORY AND
FACIAL NERVES
Inferior petrosal sinus
Petro-squamous sinus
SPINAL ACCESSORY N..
Sigmoid portion of
lateral sinus
Posterior meningeal
branch of vertebral artery
Left marginal sinus
Circular sinus
Cavernous sinus
SIXTH NERVE
Basilar artery
Basilar plexus
Auditory artery
Vertebral artery
Anterior spinal artery
HYPOGLOSSAL NERVE
SPINAL ACCESSORY
NERVE
Right marginal sinus
Occipital sinus
Left lateral sinus
Superior longitudina
sinus
Right lateral sinus
arachnoid space, in the proper sense of the word, does not exist; it is convenient,
however, to retain the term to designate the region which is occupied by the sub-
arachnoid tissue, and to speak of the accumulations of this tissue which are
formed in regions where the distance between the arachnoid and pia mater is
increased as subarachnoid spaces. It should be understood, however, that in these
larger spaces the subarachnoid tissue is less abundant and the meshes are larger
than in the regions where the arachnoid and the pia mater are more approximated.
The largest of these spaces is the cisterna magna, which is a continuation
of the posterior subarachnoid space of the spinal cord. This space appears
triangular in sagittal section. It is bounded in front by the layer of pia mater
(tela choroidea inferior, page 757) which closes in the lower part of the roof of the
fourth ventricle, and above by the inferior vermiform process of the cerebellum.
It extends laterally as far as the outer margins of the tonsillar lobes. It communi-
cates with the fourth ventricle by means of three small openings; the principal of
these (foramen of Majendie) is in the middle line of the tela choroidea inferior
PIA MATER-LYMPHATICS OF BRAIN
717
immediately above the obex (page 758). The two others (foramina of Key and
Retzius) are at the extremities of the recessus laterales of the fourth ventricle,
behind the upper roots of the glosso-pharyngeal nerves. Another large space, the
cisterna pontis, is continued from the anterior subarachnoid space of the cord, and
extends forwards as far as the commencement of the great longitudinal fissure,
and laterally to the inner margins of the temporo-sphenoidal lobes. The basilar
artery and the circle of Willis are placed in this space. The cisterna pontis
communicates freely around the medulla oblongata with the cisterna magna-thus
the medulla is encircled by a wide subarachnoid space.
A large space is also to be found between the lower edge of the falx cerebri
(where the arachnoid passes across from one cerebral hemisphere to the other) and
the upper surface of the corpus callosum. This space contains the trunks and
larger branches of the anterior cerebral arteries. Another considerable space
exists in the fissure of Sylvius, and in this the middle cerebral artery ramifies.
Thus, with the exception of the cisterna magna, all these spaces serve for the
accommodation of large arteries. There is also a space between the corpora quadri-
gemina and the anterior extremity of the superior vermiform process of the cere-
bellum, and through this the veins of Galen pass to terminate in the straight sinus.
The PIA MATER is a delicate vascular membrane which closely invests the
nervous substance. It follows accurately the contour of the surface of the brain,
dipping into all the fissures of the cerebrum and cerebellum-in the smaller sulci
of the latter, however, a double layer cannot be distinctly made out. Processes or
folds of this membrane project into some of the ventricles of the brain, and are
separated from the ventricular cavities only by a layer of epithelium. These
folds form the velum interpositum and choroid plexuses, which will be described
with the anatomy of the ventricles. The blood-vessels, which divide freely in the
subarachnoid tissue, subdivide into the pia mater, forming by their inosculations
fine networks from which innumerable minute vessels proceed to penetrate the
nervous substance.
LYMPHATICS OF THE BRAIN AND SPINAL CORD
The lymphatics of the brain and spinal cord are peculiar, inasmuch as they open into
the subarachnoid space, and are only indirectly connected with the general lymphatic and
venous systems. The communications with the venous system are effected by the Pacchio-
nian bodies. The lymphatics of the peripheral nerves are in the form of tubular spaces
placed between the lamella of the perineural sheaths. These tubular channels open into
the subdural and subarachnoid spaces.
The subdural space is a very narrow interval between the dura mater and arachnoid (page
715). It normally contains only sufficient fluid to moisten its surfaces. It is in communication
with the lymphatics of the neck and also of the back and loins. It also communicates with
the perineural spaces around the nerves, and with the lymph spaces which surround the
olfactory, optic, and auditory nerves. It sends prolongations around the Pacchionian bodies.
It does not communicate with the subarachnoid space.
The subarachnoid space contains the greater part of the cerebro-spinal fluid, the fluid occupy-
ing the meshes of the subarachnoid tissue. The lymphatics of the brain and cord and also
the perineural spaces of the nerves open into this space. It is also in communication with
the ventricular system of the brain by means of the foramen of Majendie and the foramina
of Key and Retzius. Slit-like communications between the subarachnoid space and the
descending horn of the lateral ventricle have also been described (Merkel and Mierzejewsky).
It also communicates with the perilymph spaces of the internal ear and with the lymphatics
of the mucous membrane of the nose. It sends prolongations around the optic and auditory


nerves.
The lymphatic vessels of the brain and cord surround the arteries, and are hence called
perivascular lymphatics. As each artery dips into the nervous substance it carries with it
a tubular process of the pia mater. This tubular process is lined by endothelial cells and a
similar layer covers the coat of the artery. In this manner the lymph-space is bounded.
The perivascular lymphatic follows the artery as far as its capillary ramifications.
There is a lymph-space between the two layers of the spinal pia mater. Lymph-spaces
between the outer and middle coats of the cerebral arteries (Virchow-Robin space) and others
718
MALL THE NERVOUS SYSTEM
around the individual nerve-cells of the brain have been described, but these are very generally
believed to be artificial, being due to shrinking from the action of reagents. According
to Obersteiner, however, the existence of the pericellular spaces is proved by the presence
within them of lymphatic cells.' The so-called epicerebral and epispinal spaces, situated
between the deep surface of the pia mater and the nervous substance, are also artificial.
Structure of a Pacchionian body.-A Pacchionian body consists of (a) a central core of
subarachnoid tissue which is joined to the general subarachnoid tissue by a comparatively
narrow stalk. This is limited by (b) a layer of arachnoid; around which is (c) a prolon-
gation of the subdural space. Bounding this space is (d) a very thin layer of membrane
derived from the inner layer of the dura mater. It has been shown experimentally that
injections thrown into the subarachnoid space permeate the Pacchionian bodies and pass
into the venous sinuses into which these bodies project. In this course the injection dis-
tends the subdural space of the Pacchionian body, but does not enter the general subdural
space. It should be mentioned, however, that anatomical pores by which the injection could
pass do not exist. It is probable from these experiments that an outlet for the cerebro-
spinal fluid is provided by the Pacchionian bodies.
Cerebro-spinal fluid.-The cerebro-spinal fluid occupies the subdural and subarachnoid
spaces of the brain and cord and also the ventricular cavities of the brain. The average quantity
is about two ounces (Landois and Stirling). Its specific gravity is about 1010. It is of a
very pale yellow colour, and presents many of the characters of ordinary lymph, but differs
from lymph in not being coagulable, as it does not contain either fibrin factors or fibrin
ferment. It contains a substance which acts on Fehling's solution like dextrose, but which
is not a sugar (Foster).
The cerebro-spinal fluid is derived in part from the lymphatic vessels which open into
the subarachnoid and subdural spaces, but is also believed to be secreted by the epithelial
cells which cover the choroid plexuses. These cells are cubical in form, and resemble
secreting cells; a process of the choroid plexus covered by these cells has been aptly
compared by Foster to an everted alveolus of a secreting gland, with the epithelium outside
and the blood-vessels within.'

THE ENCEPHALON
The encephalon, or brain, is the portion of the cerebro-spinal axis which is
lodged within the cranial cavity and constitutes (by weight) about 98 per cent. of
the whole. It consists of the cerebrum, the cerebellum, the pons Varolii, and the
medulla oblongata. The medulla is continuous with the spinal cord at the decus-
sation of the pyramids. The encephalon, taken as a whole, is ellipsoidal or ovoidal
in form, presenting above a tolerably even convexity formed by the cerebral hemi-
spheres, but below a more irregular surface corresponding to the fosse in the base of
the skull. The cerebrum comprises the cerebral hemispheres containing the lateral
ventricles (prosencephalon), the optic thalami with the third ventricle between them
(thalamencephalon), and the mesencephalon. It occupies the upper compartment
of the cranial cavity, resting on a floor formed by the anterior and middle cranial
fossæ and the tentorium cerebelli. The cerebellum occupies the posterior cranial
fossa, and is placed above and behind the fourth ventricle. It is connected by three
pairs of peduncles or crura to the cerebrum, pons, and the medulla respectively.
The fourth ventricle is bounded below and in front by the pons and medulla.
In every part of the encephalon two distinct kinds of nervous substance are to be met
with, termed grey and white matter. The grey matter is chiefly disposed upon the surface,
as in the convolutions of the cerebrum and cerebellum; but it is also met with in detached
or partially detached masses or nuclei, such as the corpora striata and optic thalami in the
cerebrum, the nuclei of the medulla and pons, and the corpus dentatum of the cerebellum.
It is composed of groups of ganglion cells, which possess the power of originating nervous
impulses; or of receiving impulses produced by the action of external stimuli on the end-
organs of nerves; or of modifying and redirecting such impulses. The white matter occurs
in the greatest quantity in the central parts of the cerebral hemispheres. It is composed
of medullated nerve-fibres, which conduct the impulses to and from the ganglion cells in
the grey matter. Both grey and white matter are supported by a delicate interstitial tissue
termed neuroglia.

THE BRAIN
719
BASE OF THE BRAIN

Dissection. The student is recommended to commence the dissection of the brain by a
general examination of the structures forming the base of that organ. He should carefully
remove the remains of the membranes from the base, and after studying that region should
proceed in a similar manner to remove the membranes from the superior and lateral
surfaces of the cerebral hemispheres.
The base of the brain presents for examination the inferior surfaces of the frontal and
temporo-sphenoidal lobes of the cerebrum; the structures contained within and adjacent to
the interpeduncular space; the inferior surfaces of the pons Varolii, medulla oblongata, and
lateral hemispheres of the cerebellum; and the superficial origins of the cranial nerves.
In front, the orbital surfaces of the frontal lobes are seen separated from one another by
the great longitudinal fissure, and indented by the triradiate and olfactory sulci, the latter
FIG. 408.-VIEW OF THE BASE OF THE BRAIN. (After Beaunis.)

Бо
OLFACTORY BULB
OPERCULUM
2nd or OPTIC NERVE
3rd or OCULO-MOTOR-
4th or TROCHLEAR
5th or TRIGEMINAL-
6th or ABDUCENT-
7th or FACIAL
8th or AUDITORY
9th, GLOSSO-PHARYNG.
10th, PNEUMOGAST.-
11th, SPINAL ACCESS.-
12th, HYPOGLOSSAL
hits alond on
TRIRADIATE
FISSURE
ANTERIOR
PERFORATED
SPACE
PITUITARY BODY
TUBER CINEREUM
CORPUS ALBICANS
POST. PERF. SPACE
CRUS CEREBRI
PONS VAROLII
PYRAMIDAL BODY
OLIVARY BODY
AMYGDALA
SECTION OF
SPINAL CORD
INFERIOR
VERMIFORM
PROCESS
occupied by the olfactory tract and bulb. Behind and somewhat laterally the frontal lobes
are marked off from the temporal lobes by the fissure of Sylvius, near the commencement of
which is the anterior perforated space. This space is of a grey colour, and is formed by a
part of the lenticular nucleus of the corpus striatum, which comes to the surface at the
base of the brain. The perforations are caused by small arteries which proceed from the
middle cerebral artery to the corpus striatum. Each space is bounded internally by one
of the peduncles of the corpus callosum. The latter are white bands which pass from the
corpus callosum to the commencement of the fissure of Sylvius. Between the temporo-
sphenoidal lobes is a large recess, which is bounded in front by the frontal lobes, and behind
by the pons Varolii; within this is the remarkable arterial anastomosis known as the circle
of Willis, the crura cerebri, the interpeduncular space, portions of the optic tracts with the
optic commissure, the lamina cinerea, and portions of the third and fourth pairs of nerves.
720
THE NERVOUS SYSTEM

The interpeduncular space is situated between the diverging crura cerebri. It corresponds
below to the deepest part of the cisterna pontis, and above to the posterior part of the
floor of the third ventricle. It contains (1) the posterior perforated space, and in front of
this (2) a pair of white rounded eminences, the corpora albicantia or mammillaria, and (3)
a conical greyish elevation, the tuber cinereum, ending in a thin tubular process, the
infundibulum. The latter passes to the pituitary body, from which it is detached in
removing the brain by the ordinary method. Immediately in front of the tuber cinereum
is the optic commissure, from which the optic tracts can be traced for a short distance
backwards and outwards, winding round the crura cerebri, and finally disappearing under
cover of the temporal lobes. A thin grey lamina, the lamina cinerea, passes from the
anterior border of the optic commissure to the commencement of the great longitudinal
fissure, where it gains an attachment to the rostrum of the corpus callosum. The crura
cerebri appear as two strong flattened bundles of white fibres, which emerge from the
anterior border of the pons, and, diverging from one another, pass under cover of the
temporal lobes, and are soon lost to view. On each side the third nerve is seen passing
between the posterior cerebral and superior cerebellar arteries. Each nerve springs by a
row of filaments from a groove at the inner margin of the crus. The fourth nerve, a slender
rounded fasciculus, winds round the outer side of the crus. The pons Varolii appears
immediately behind the crura as a broad band of white fibres directed transversely, and
passing from one cerebellar hemisphere to the other. It narrows on each side as it passes
into the cerebellum. It is marked by a shallow groove in the middle line in which the
basilar artery rests. The fifth nerve is seen piercing the side of the pons near its upper
border in the form of two bundles, a large posterior or sensory root, and a small anterior or
motor root, separated from the former by some of the transverse fibres of the pons. The
sixth nerves are seen at the lower border of the pons in the groove between it and the
medulla, emerging from the latter close to the outer side of the pyramidal bodies or between
the fibres of these bodies. The pyramidal and olivary bodies can readily be made out on
the medulla, and a portion of the restiform body can also be seen without disturbing the
parts. The twelfth or hypoglossal nerve emerges by a row of filaments from the groove
between the olivary and pyramidal bodies. The ninth, tenth, and eleventh nerves, which
appear in numerical order from above downwards, arise from the groove between the
olivary and restiform bodies; the origin of the eleventh or spinal accessory nerve being
continued down the lateral column of the cord. The seventh and eighth nerves are close to
the edge of the pons in the angle between the latter and the cerebellum. The cerebellar
hemispheres are placed one on each side of the medulla and conceal the occipital lobes of
the cerebrum when viewed from the base. The cerebellum stands out conspicuously from
the cerebrum on account of its darker grey colour and the smaller size and narrowness of
its convolutions, which are termed folia. Two of its lobes are more prominent than the
rest, viz. the amygdala or tonsils, which are placed close to the medulla, one on each side;
and the flocculi, which lie close to the pons above the tenth or pneumogastric nerves.



THE CEREBRAL HEMISPHERES
The cerebral hemispheres constitute about 89 per cent. of the entire brain, and
viewed from above, present an ovate form, broader behind than in front. They
contain the lateral ventricles in their interior. They are separated from one another
by the great longitudinal fissure, the floor of which is formed by the corpus callo-
sum, a great commissure which connects each hemisphere with its fellow. Each
hemisphere presents for examination a supero-external, an inferior, and an internal
surface, and two extremities or poles, an anterior and a posterior; the anterior
pole presenting an edge flattened internally and bevelled externally; the posterior
forming a blunt rounded point which is directed backwards with an inclination
downwards. With the exception of a small portion of the inferior surface, the
cerebral hemispheres are entirely covered with fissures or sulci, which mark off
intervening elongated elevations termed convolutions or gyri. By this means the
surface area of the brain and consequently the proportion of grey to white matter is
very greatly increased. The general arrangement of the convolutions in the two
hemispheres of the same brain is tolerably symmetrical, but minor differences always
occur. These differences are more particularly seen when there is any striking
deviation from the normal arrangement, as such abnormalities are usually con-
fined to one hemisphere. The supero-external surface is convex, presenting a

FISSURES OF CEREBRUM
721
sharper curve in the transverse than in the antero-posterior direction. It is marked
off from the internal surface at the great longitudinal fissure by a well-defined edge.
It is divided for about its middle third into a superior and an inferior segment by the
horizontal limb of the fissure of Sylvius which marks off the temporo-sphenoidal
lobe. The internal surface is flattened, and is separated from the opposite hemi-
sphere by the falx cerebri and the subarachnoid space. The inferior surface presents,
in its middle third, a well-marked projection (the temporal pole of Broca) caused by
the temporal lobe, in front of which is the commencement of the fissure of Sylvius,
which separates the temporal lobe from the orbital surface of the frontal lobe.
FIG. 409.-THE FISSURES AND CONVOLUTIONS OF THE CEREBRUM, VIEWED FROM ABOVE.
ORBITAL
MARGIN
SUPERIOR
FRONTAL
CONVOLUTION
MIDDLE
FRONTAL
CONVOLUTION
INFERIOR
FRONTAL
CONVOLUTION
SUPERIOR
FRONTAL
FISSURE
ASCENDING
FRONTAL
CONVOLUTION
ASCENDING-
PARIETAL
CONVOLUTION
SUPRA-
MARGINAL
CONVOLUTION
SUPERIOR
PARIETAL LOBULE
FRONTAL
PARIETAL
VLOBE
ANGULAR GYRUS
MIDDLE OCCIPITAL
CONVOLUTION
OCCIPITAL
LOBE
SUPERIOR OCCIPITAL-
CONVOLUTION
INFERIOR
PRE-
CENTRAL
FISSURE
SUPERIOR
PRE-
CENTRAL
FISSURE
INTRA-
PARIETAL
FISSURE
CALLOSO-
MARGINAL
FISSURE
SULCUS
OCCIPITALIS
ANTERIOR
EXTERNAL
PARIETO-OCCIPI-
TAL FISSURE
TRANSVERSE OCCI-
PITAL FISSURE
SUPERIOR OCCIPI-
TAL FISSURE
Fissures.-Under this term are included: (a) narrow intervals formed by the
approximation of parts primitively widely separated, and (b) fissures due to
infoldings of the ventricular wall for a part or the whole of its thickness. Only
two fissures are included in the former category, viz. the great longitudinal and the
great transverse fissures of the cerebrum. (a) The great longitudinal fissure
extends from the frontal to the occipital pole of the cerebrum and separates the
hemispheres from one another, except where they are joined by the corpus callosum.
It contains the falx cerebri and the anterior cerebral arteries. The great trans-
verse fissure will be described with the anatomy of the lateral and third ventricles.
(b) The remaining fissures present a very distinct division into complete and
incomplete. The complete fissures are formed by an infolding of the entire
3 A
722
THE NERVOUS SYSTEM
6
thickness of the ventricular wall, so that the reverse of each complete fissure
appears as a bulging into the cavity of the ventricles. The complete fissures
comprise the dentate fissure, the collateral fissure, the calcarine fissure, and parieto-
occipital fissure. The fissure of Sylvius is sometimes described as a complete fissure,
but the projection into the hemisphere cavity which corresponds with it (viz. the
corpus striatum) is not formed by an infolding of the mantle wall, but as an
elevation on the floor of the prosencephalon. The surface area corresponding
to this internal projection does not keep pace with the mantle, as the latter grows
around it, and in consequence the Sylvian depression makes its appearance.'
(Cunningham.)
Interlobar fissures.-Certain fissures are termed interlobar because they have
been selected to determine the boundaries of the various lobes into which the
hemispheres have been (somewhat artificially) divided. These are the parieto-
occipital fissure and the fissures of Sylvius and of Rolando.
The parieto-occipital fissure appears as a well-marked vertical sulcus on
the posterior part of the inner face of the hemisphere, and is continued outwards
for a short distance on to the convex surface. The portion on the mesial surface
is distinguished as the internal parieto-occipital or internal perpendicular fissure.
It will be more particularly described with the fissures and convolutions of the
inner surface of the hemisphere. The portion which appears on the convex surface
is distinguished as the external parieto-occipital fissure.
The fissure of Sylvius is situated partly on the base and partly on the external
surface of the hemisphere, and is, with the exception of the great longitudinal
fissure, the most conspicuous sulcus in the brain. It commences at the outer
angle of a depression called the vallecula Sylvii, in which the anterior perforated
space is situated. It passes outwards and upwards with an inclination backwards,
and divides into three branches or limbs, a posterior, an ascending, and an anterior.
The posterior limb is by far the largest, and is to be regarded as the continuation
of the main fissure; it passes backwards and slightly upwards, separating the
temporal from the frontal and parietal lobes, and finally, taking a more upward
direction, ends in the parietal lobe. The ascending limb is short and passes
vertically upwards; the inferior frontal convolution arches around it. The anterior
limb is about the same length as the ascending; it passes directly forwards into the
substance of the inferior frontal convolution.
Between the posterior and ascending limbs of the fissure of Sylvius, a wedge-shaped
mass of convolutions is included which is known as the operculum; it belongs partly to the
frontal and partly to the parietal lobes. Beneath the operculum the two limbs of the fissure
of Sylvius are united by a fissure which takes a curved course concentric with the cerebral
surface; this fissure or space corresponds to the floor of the originally open fossa Sylvii,
which has been covered by the downward growth of the operculum. When it is opened
up by raising the operculum, the island of Reil is displayed.
The fissure of Rolando, or central sulcus, serves as a line of demarcation between
the frontal and parietal lobes. It is, next to the fissure of Sylvius, the most
important of the incomplete fissures of the brain. It extends from the great
longitudinal fissure to the Sylvian fissure, and may communicate with the latter
(19 per cent., Cunningham), but the communication is always shallow. At its upper
end it usually (60 per cent., Cunningham) passes into the great longitudinal fissure
and appears on the mesial surface of the hemisphere, where it ends by bending
backwards for about a quarter of an inch. The fissure of Rolando is directed
downwards and forwards so that the fissures of the two sides taken together form
an angle of about 143°, open in front. The fissure does not pursue a perfectly
straight course, but is somewhat sinuous, and two of its bends, more conspicuous
and constant than the others, have been described as the superior and inferior
genua. These genua mark off the fissure into three approximately equal parts.


FISSURE OF ROLANDO
723
The superior genu is directed backwards. The inferior genu looks forwards; it
is more constant and much more strongly marked than the superior genu. In rare
cases the fissure of Rolando may communicate with the præcentral or intraparietal
sulci, but as a rule it pursues an isolated course across the convex surface.
It has been very generally taught that the fissure of Rolando is caused by the pressure
of a vein which passes during foetal life (from the fourth to the sixth month) from the
middle cerebral vein to the superior longitudinal sinus. This view has been recently
disproved, as it has been shown that the fissure develops in two segments, an upper and a
lower, and the fissure is afterwards completed by the sinking down of the central portion.
The remains of this central elevation can always be seen on opening the fissure of Rolando
as a deeply placed annectant or bridging convolution at the level of the superior genu.
(Cunningham.)
The fissure of Rolando is one of the earliest of the incomplete fissures to appear, and is
usually developed during the last week or ten days of the fifth month of intra-uterine life.
By its transverse direction it interrupts the longitudinal course of the majority of the
FIG. 410.-LATERAL VIEW OF THE FISSURES AND CONVOLUTIONS OF THE CEREBRUM.
SUPERIOR
PRE-
INTRAPARIETAL
FISSURE
SUPERIOR PARIETAL
LOBULE
SUPRA-MARGINAL
CONVOLUTION
ANGULAR
GYRUS
EXTERNAL
PARIETO-
OCCIPITAL
FISSURE
SUPERIOR
OCCIPITAL
CONVOLUTION-
TRANSVERSE
OCCIPITAL
FISSURE
INFERIOR
OCCIPITAL
CONVOLUTION
ASCENDING
PARIETAL FISSURE OF CENTRAL
CONVOLUTION ROLANDO FISSURE
ASCENDING SUPERIOR
FRONTAL
FRONTAL
CONVOLUTION FISSURE
SUPERIOR
FRONTAL
CONVOLUTION
FRONTAL LOBE
PARIETAL LOBE
OCCIPITAL LOBE
21
TEMPORO-SPHENOIDAL LOBE
PRE-OCCIPITAL SULCUS n
NOTCH
SUPERIOR
OCCIPITALIS
TEMPORAL
ANTERIOR
FISSURE
MIDDLE
TEMPORAL
FISSURE
INFERIOR
FRONTAL
FISSURE
MIDDLE
FRONTAL
CONVOLU-
TION
SULCUS
FRONTO-
MARGINA-
LIS
ORBITAL
MARGIN
INFERIOR
FRONTAL
CONVOLU
TION
ORBITAL SURFACE
SUPERIOR TEMPORAL
CONVOLUTION
MIDDLE TEMPORAL
CONVOLUTION
INFERIOR
TEMPORAL
CONVOLUTION
cerebral fissures; this peculiarity is shared, however (but not so constantly), by the
præcentral sulcus and by the vertical part of the intraparietal fissure. It is one of the
most important landmarks on the cerebral surface, as the principal motor centres of the
cortex are situated around it.
THE LOBES OF THE CEREBRAL HEMISPHERES WITH THE FISSURES AND
CONVOLUTIONS
Each cerebral hemisphere is divided into five lobes, viz. the frontal, parietal,
occipital, temporo-sphenoidal, and the central lobe or island of Reil. Four of these
lobes are visible on the peripheral part of the hemispheres; the fifth, or island of
Reil, is deeply placed and is concealed by the operculum.
Two other lobes, the falciform and the so-called olfactory lobe, are also
described. The falciform lobe is limited to the mesial and tentorial surfaces of
3A 2
724
THE NERVOUS SYSTEM
the hemisphere, and will be described later on. The so-called olfactory lobe attains
a considerable size in some of the lower animals, and may contain a prolongation
of the lateral ventricle in its interior; in man, however, although hollow in
embryonic life, it is reduced to a solid olfactory tract and bulb of small size. The
olfactory tract and bulb are described for convenience among the cranial nerves,
and are termed the olfactory or first pair of nerves.
The rhinencephalon (so-called olfactory lobe) is a secondary outgrowth from the primitive
cerebral vesicle, and therefore does not come under the same category as the cerebral lobes.
It bears the same relation to the prosencephalon that the latter does to the thalam-
encephalon.
The FRONTAL LOBE occupies the fore part of the hemisphere and presents
three surfaces: a convex supero-external or frontal, an inferior or orbital, and an
internal or mesial. The convolutions and fissures on the mesial and tentorial
surfaces of the hemisphere will be described separately. The frontal lobe is bounded
behind by the fissure of Rolando, and below, for about its posterior half, by the stem
and posterior limb of the fissure of Sylvius. It is limited internally by the calloso-
marginal fissure.
The frontal surface is separated from the orbital by a well-marked angle which
may be called the orbital margin. This margin is usually destitute of fissures, and
forms a curve concentric with the orbital arch of the frontal bone. Three fissures
on the frontal surface require description: one of these, running in a transverse
direction, is termed the præcentral, the other two, which run parallel to the great
longitudinal fissure, are named superior and inferior frontal.
The præcentral sulcus is placed in front of and parallel to the fissure of Rolando,
and is usually divided by a sagittally-placed convolution into two parts, a superior
and an inferior præcentral; the former is usually continuous with the superior
frontal fissure.
The superior frontal fissure is sometimes discontinuous with the præcentral.
At its orbital end it often passes into a coronally placed, curved fissure, termed the
sulcus fronto-marginalis. The latter is situated just above the orbital margin of
the frontal lobe.
The inferior frontal fissure may be continuous with the præcentral, but a
narrow gyrus usually separates the two fissures.
The convolutions on the frontal surface are four in number: one directed trans-
versely, the ascending frontal; and three lying in an antero-posterior direction,
named superior, middle, and inferior frontal.
The ascending frontal convolution bounds the fissure of Rolando in front, and
is placed between that fissure and the præcentral sulcus. It is connected at each
end of the fissure of Rolando with the ascending parietal convolution, and passes
into the paracentral lobule on the inner face of the hemisphere.
The superior, middle, and inferior frontal convolutions occupy the remainder of
the frontal surface, and are marked off by the superior and inferior frontal fissures.
They pass forwards, and become continuous with the convolutions on the orbital
surface. They are not simple, but are traversed both in a coronal and sagittal
direction by tertiary fissures.
The superior frontal convolution is continuous behind with the ascending
frontal, and passes in front into the gyrus rectus and into the internal and anterior
orbital convolutions. It is continuous with the marginal convolution on the inner
face of the hemisphere.
The middle frontal convolution is continuous behind with the ascending frontal
when the superior and inferior præcentral fissures are discontinuous. It passes in
front into the anterior orbital gyrus. It is almost invariably continuous with the
superior and inferior frontal convolutions at the orbital margin of the frontal lobe,
FRONTAL AND PARIETAL LOBES
725
and is often connected to these convolutions by secondary gyri passing across the
superior and inferior frontal fissures.
The inferior frontal convolution is continuous behind with the ascending
frontal, and joins the external orbital gyrus around the orbital margin. The
ascending and anterior limbs of the fissure of Sylvius cut into the substance of this
convolution, and divide it into three parts, viz. pars orbitalis, pars triangularis, and
pars basilaris. The pars orbitalis is situated below the anterior limb of the Sylvian
fissure. The pars triangularis is included between the ascending and anterior limbs
of the fissure. The pars basilaris is placed behind the ascending limb of the
Sylvian fissure between the latter and the inferior præcentral sulcus.
This convolution is of great physiological interest, as the faculty of articulate speech is
localised in its posterior part (Broca's convolution). Disease of this limited portion of brain
substance on the left side produces aphasia, except in left-handed persons, in whom the
speech-centre is placed in the corresponding position on the right side. The speech-centre
is limited to the pars basilaris. According to Ferrier, the speech-centre includes (in
addition to the above) the inferior extremity of the ascending frontal convolution and a
small part of the ascending parietal immediately behind the lower end of the fissure of
Rolando.
The orbital surface of the frontal lobe appears flattened in brains hardened in
the ordinary manner; but when the brain is hardened in situ (fig. 410) it pre-
sents a very characteristic concavity, being moulded on the orbital plate of the
frontal bone. The outer half of the orbital surface looks directly downwards, but
the inner half, following the curve of the orbital plate, looks much more outwards
than downwards, and forms a tolerably sharp edge where it meets the internal
surface. Two fissures are situated on this surface, viz. the triradiate and the
olfactory.
The triradiate fissure, as its name implies, is formed by three branches, which
radiate from a common point. One branch is directed forwards, another backwards
and inwards, and the third outwards. Another branch frequently springs from
the external division near its centre, and in such cases the triradiate fissure assumes
an H-shaped outline.
The olfactory or straight sulcus is placed a short distance external to the great
longitudinal fissure, and lodges the olfactory tract and bulb.
The convolutions on the orbital surface comprise the three orbital convolutions
and the straight convolution.
The orbital convolutions are wedge-shaped masses placed between the limbs of
the triradiate fissure. They are called, from their position, internal, anterior, and
posterior. They are continuous with the superior, middle, and inferior frontal
convolutions respectively.
don
The straight convolution, or gyrus rectus, is situated between the sulcus of the
same name and the margin of the great longitudinal fissure. It is continuous in front
with the superior frontal convolution, and on the inner margin of the hemisphere
with the marginal gyrus. It is sometimes described as a part of the internal
orbital convolution.
The convolutions on the internal surface of the frontal lobe are the marginal and the
paracentral. The student is recommended to defer the study of these till a later period
(page 731).
The PARIETAL LOBE occupies the portion of the convex surface between the
frontal and occipital lobes and above the temporal lobe. It is bounded in front by the
fissure of Rolando. Internally it is continued into the mesial surface of the hemi-
sphere, where it is marked off from the adjacent lobes by the upturned end of the
calloso-marginal fissure in front, by the internal parieto-occipital fissure behind,
and more obscurely below by the variable sulcus subparietalis. On the convex
surface of the hemisphere the posterior limits of the parietal lobe are in a great

726
THE NERVOUS SYSTEM
measure artificial. The external parieto-occipital fissure marks it off for a short
distance, and the boundary is then crossed by convolutions termed annectant gyri,
which run in a sagittal direction and so bring the parietal and occipital lobes into
direct continuity. There is, however, a notch, the pre-occipital notch (fig. 410),
placed at the lower margin of the hemisphere between the occipital and temporal lobes,
and if a line be drawn from the extremity of the external parieto-occipital fissure
to this notch, the upper part of the line, together with the external parieto-occipital
fissure, separates the parietal from the occipital lobe. The parietal lobe is limited
below by the posterior limb of the Sylvian fissure in the horizontal part of its
course, and behind this its lower limits are artificially mapped out by producing the
horizontal part of the Sylvian fissure backwards to meet the posterior boundary.
The parietal lobe contains one fissure of importance-the intraparietal.
The intraparietal fissure is a system of three fissures, viz. a superior and an
inferior vertical, placed parallel to the fissure of Rolando; and a horizontal placed at
right angles to the other two. These parts may in rare cases remain separate, but
most commonly are united with one another, forming a T-shaped figure. More-
over, the horizontal part may unite with a fourth part, the ramus occipitalis, which
extends into the occipital lobe.
The intraparietal fissure has been hitherto regarded as consisting of an ascending and a
horizontal part; the upper vertical limb (postcentral sulcus) being detached. This is a
common variety of the fissure, but it has recently been shown that the T-shaped form is
the commonest or normal arrangement. (Cunningham.)
The convolutions of the parietal lobe are: an ascending parietal, bounding the
fissure of Rolando posteriorly and placed between that fissure and the intraparietal
sulcus; and two parietal lobules, a superior and an inferior, placed above and below
the horizontal limb of that fissure. The inferior parietal lobule is further sub-
divided into an anterior part called the supramarginal convolution, and a posterior
termed the angular gyrus.
The ascending parietal convolution extends from the posterior limb of the
Sylvian to the great longitudinal fissure, and is bounded in front by the fissure of
Rolando, and behind by the intraparietal sulcus. It is continuous with the supra-
marginal convolution below the intraparietal fissure, and at its upper end is con-
tinued into the paracentral lobule on the inner surface of the hemisphere.
The superior parietal lobule is a squarish mass indented on the surface by
tertiary fissures. It is limited internally by the margin of the great longitudinal
fissure where it becomes continuous with the præcuneus. The anterior end of the
ramus occipitalis of the intraparietal fissure terminates in this lobule when it is
not continuous with the remainder of the intraparietal fissure, and, in such cases,
the superior and inferior parietal lobules are continuous posteriorly. The superior
parietal lobule is joined in front, by a convolution of variable breadth, with the
ascending parietal, and is connected behind to the superior occipital convolution by
the first annectant gyrus.
The supramarginal convolution is the anterior part of the inferior parietal
lobule. It arches around the upturned extremity of the posterior limb of the
fissure of Sylvius. It is continuous in front with the ascending parietal convolu-
tion, behind with the superior temporal gyrus and also with the angular gyrus. It
is often very obscurely marked off from the latter.
The angular gyrus is placed behind the preceding and embraces the extremity
of the parallel fissure. It is continuous behind with the middle temporal convolu-
tion. It is also usually connected to the middle occipital convolution by the third
annectant gyrus.
The OCCIPITAL LOBE occupies approximately the portion of the cranial cavity
which is interposed between the superior fossæ of the occipital bone and the



OCCIPITAL LOBE
727
tentorium cerebelli. It presents three very distinct surfaces: a convex supero-external,
a mesial or internal, and a tentorial. The latter looks downwards and slightly
inwards. These three surfaces meet at the occipital pole. It is sharply marked
off on the mesial surface by the internal parieto-occipital fissure. On the convex
surface the line of demarcation (as already described in treating of the parietal
lobe) is made by drawing a line from the extremity of the external parieto-occipital
fissure to the præoccipital notch (fig. 410). This line separates the occipital from
the parietal and temporal lobes.
The præoccipital notch (fig. 410) is produced by the impression of the veins
which enter the lateral sinus. Another impression (fig. 410, n), which is produced
by the superior border of the petrous portion of the temporal bone, has been some-
times described as the præoccipital notch.
It is generally stated that the occipital lobe passes into the temporal lobe on the tentorial
surface without any line of demarcation. A number of methods of marking off the occipital
lobe have been proposed by different authors. These are all largely artificial. The occipital
lobe is due to a backward growth common to the parietal and temporal lobes. That growth
carries with it a prolongation of the lateral ventricle, forming the posterior cornu. The
occipital lobe is therefore that part of the hemisphere which contains the posterior cornu.
It may be marked off on the tentorial surface by a line drawn from the præoccipital notch
to the extremity of the parieto-occipital fissure at the isthmus of the gyrus fornicatus
(fig. 411). The remaining boundaries will be the parieto-occipital fissure for its entire
length and (as before) a line drawn from the extremity of the external parieto-occipital
fissure to the præoccipital notch.
The fissures on the convex surface of the occipital lobe are the superior, middle,
and inferior occipital fissures; to these may be added the ramus occipitalis of the
intraparietal fissure with its appendage the transverse occipital fissure.
The superior occipital fissure may be represented by a direct continuation of
the intraparietal fissure to the occipital pole of the cerebrum. More commonly,
however, it is limited to the posterior part of the occipital lobe (fig. 409, right side),
and is not continuous with the intraparietal fissure. The ramus occipitalis of the
intraparietal fissure may be directly continued into the occipital lobe from the
horizontal limb of the main fissure, or it may commence in the superior parietal
lobule. In either case it passes backwards into the occipital lobe between the
first and second annectant gyri, and usually terminates a short distance behind
the external parieto-occipital fissure by dividing into two branches which extend
upwards and downwards at right angles to the main fissure, and together constitute
the transverse occipital fissure.
In the brains of most apes a fissure extends across the hemisphere in a line with the
upper end of the internal parieto-occipital fissure, and is often said to be homologous with
the external parieto-occipital fissure of the human brain. This characteristic simian
fissure (appropriately called, in Germany, the Affenspalte) is, however, formed by the anterior
margin of an occipital operculum, that is to say, a portion of brain substance which has
grown forwards from the occipital lobe, and has concealed the true external parieto-occipital
fissure and the annectant gyri. These structures can, however, be readily seen if this
operculum be lifted up. The occipital operculum and Affenspalte are probably formed by
the forward growth of the convolution which bounds the transverse occipital fissure pos-
teriorly, the parts immediately in front of this fissure being checked in their growth and
depressed below the surface. For further information the student is referred to the works
of Gratiolet, Schwalbe, and to a recent paper by D. J. Cunningham on the intraparietal
fissure of the human brain.




The middle occipital fissure is often feebly developed. It is directed from
before backwards and meets the superior occipital fissure at the occipital pole.
The inferior occipital fissure is placed along the margin which separates the
convex surface from the tentorial surface of the hemisphere. It may extend in a
tortuous manner from the præoccipital notch to the occipital pole of the hemisphere
but is often broken up by one or more convolutions crossing it.
728
THE NERVOUS SYSTEM
The convolutions on the convex surface are three in number, and are imper-
fectly marked off from one another by the fissures above described. They pass
from before backwards and become confluent at the occipital pole.
The superior occipital convolution is placed between the superior occipital
fissure and the margin of the great longitudinal fissure. It is continuous with the
cuneus on the inner surface of the hemisphere, and is joined in front by the first
annectant gyrus to the superior parietal lobule.
The middle occipital convolution is situated between the superior and middle
occipital fissures, and is united in front to the angular gyrus by the second and
third annectant gyri.
The inferior occipital convolution occupies the interval between the middle
and inferior occipital fissures, and may be connected to the middle temporal convo-
lution by a fourth annectant gyrus.
The annectant gyri are four small sagittally-directed convolutions which cross the
boundary line which separates the occipital from the parietal and temporal lobes. They
are numbered from within outwards. The first and second of these are the most constant
and are placed one on each side of the ramus occipitalis of the intraparietal fissure. The
third and fourth are not infrequently absent as they may be cut through by the fissure, the
sulcus occipitalis anterior.
The sulcus occipitalis anterior is an inconstant fissure which is parallel to, and placed
a little in front of, the anterior boundary of the occipital lobe on the convex surface of the
hemisphere.
The TEMPORAL LOBE (temporo-sphenoidal lobe) is sharply marked off in front
by the Sylvian fissure, but, as we have already seen, it passes behind without any
surface line of demarcation into the parietal and occipital lobes. Its anterior
extremity forms a bold prominence directed downwards and forwards (the temporal
pole of Broca). It has three surfaces: an external, forming part of the general
convexity of the hemisphere; an inferior, which rests on the great wing of the
sphenoid and the adjacent part of the petrous portion of the temporal bone; and
a superior, which is situated within the Sylvian fissure and can be displayed by
pulling up the operculum.
The boundaries of the temporal lobe have been already indicated in the description of
the other lobes, but may be recapitulated as follows. It is bounded behind by the lower
part of the line drawn from the external parieto-occipital fissure to the præoccipital notch.
Above, it is limited by the horizontal part of the posterior limb of the Sylvian fissure and
by a line continuing the horizontal direction backwards to meet the posterior boundary.
Its inferior surface may be marked off from the occipital lobe by a line drawn from the
præoccipital notch to the isthmus of the gyrus fornicatus.
Three fissures traverse the temporal lobe in a direction parallel to its long
axis. The first of these, the superior temporal or parallel fissure, is one of the
most constant of the incomplete fissures of the cerebrum. The other two, termed
middle and inferior temporal, seldom appear as well-marked sulci, being as a rule
broken up by fissures and gyri crossing at right angles to their direction.
The collateral fissure is approximately parallel to the three temporal sulci; it marks off
the temporal from the falciform lobe.
The parallel fissure commences a short distance behind the apex of the lobe,
and takes a course parallel to the posterior limb of the fissure of Sylvius. Its
upturned extremity ends in the parietal lobe, where it is embraced by the angular
gyrus.
The middle temporal fissure runs in the same general direction as the parallel
fissure but is placed at a lower level. It may communicate behind with the sulcus
occipitalis anterior.
10
The inferior temporal fissure is placed on the under surface near the lateral
margin of the hemisphere. It is in a line with the inferior occipital fissure.
TEMPORAL LOBE-ISLAND OF REIL
729
Three convolutions are present on the outer surface, running in an antero-
posterior direction. They are termed the superior, middle, and inferior temporal
convolutions. They become confluent with one another at the apex of the lobe.
The superior temporal or inframarginal convolution lies between the Sylvian
and parallel fissures. It is continuous above with the supramarginal and angular
gyri.
The middle temporal convolution, placed between the parallel and the middle
temporal fissures, is continuous behind with the angular gyrus and middle occipital
convolution. It is usually joined to the inferior occipital by the fourth annectant
gyrus.
The inferior temporal convolution is situated on the lateral margin of the
hemisphere. It may be connected to the inferior occipital convolution by a fifth
annectant gyrus.
The superior surface of the temporal lobe is in contact with the operculum. It
is crossed by two or three (sometimes four) transverse temporal convolutions.
(Heschl.)
Dissection. The student should now raise the operculum and at the same time draw
the temporal lobe downwards in order to bring the island of Reil into view. The large
branches of the middle cerebral artery which lie among the convolutions of the island should
be removed, together with the adherent pia mater.
The CENTRAL LOBE or ISLAND OF REIL corresponds to the floor of the embry-
onic fossa Sylvii, and is placed external to the claustrum. It is situated under
cover of the operculum, and is also overlapped by the temporal lobe and by the part
of the inferior frontal convolution in front of the ascending limb of the fissure of
Sylvius. It is of a triangular form with the base placed uppermost, the apex forming
a prominence, the limen insulæ, which separates the vallecula Sylvii from the fissure
of the same name. It is surrounded, except at the limen, by a curved furrow, the
sulcus circularis Reilii (Schwalbe). From five to seven convolutions, the gyri
operti, radiate from the limen insulæ. The island is divided into a larger anterior
part (pars frontalis), and a smaller posterior part (pars parieto-falciformis) by a
constant fissure, the sulcus centralis insulæ (Hefftler and Eberstaller), which has
the same direction, and is in the same plane, as the fissure of Rolando.
The pars parieto-falciformis is usually termed pars temporo-parietalis; a study of the
development of this part of the island has shown, however, that it is connected with the
falciform and not with the temporal lobe. (Cunningham.)
Dissection. The student is recommended to defer the study of the convolutions on the
mesial and tentorial surfaces of the hemisphere until the dissection of the corpus callosum
is completed, and to proceed as follows. He should make a horizontal section through the
uppermost part of the cerebral hemispheres; this will display the central core of white
matter (centrum ovale minus) surrounded by a convoluted border of grey matter. Within
the white matter a number of minute vessels will be seen which appear as bleeding points
in a fresh brain (the puncta vasculosa vel cruenta). He may then remove successive thin
sections until he reaches the level of the corpus callosum, the fibres of which, spreading
out into the hemisphere, form an extensive white layer called the centrum ovale majus. A
far more instructive dissection, however, can be made by cautiously tearing the brain
substance in a direction from within outwards until the callosal fissure is reached. By the
latter method the following points can be made out in an ordinary well-hardened brain:
(1) The white fibres entering each convolution spreading out so as to end perpendicularly
to the surface. (2) The fibres from the body of the corpus callosum passing at first hori-
zontally outwards into the hemisphere and then diverging, some sweeping upwards to the
parietal and frontal lobes, others bending downwards into the temporal lobe and following
the long axis of that lobe. At the point where they bend downwards they readily break,
as they are here intersected by fibres passing upwards from the inner capsule. (3) The
fibres from the anterior and posterior extremities of the corpus callosum passing in a curved
manner into the frontal and occipital lobes respectively, forming the forceps minor and
the forceps major. (4) A set of fibres, known as the cingulum, which run within the gyrus
fornicatus, forming a sagittally-directed arch. The dissector should next study the corpus
callosum and the convolutions on the inner face of the hemisphere. The convolutions on



730
THE NERVOUS SYSTEM
the tentorial surface may be learned from a mounted specimen, or better still from a cast
of a cerebral hemisphere, and the actual convolutions can be examined when the hemi-
spheres are cut away from the mesencephalon at a later stage.
Mesial and tentorial surfaces of the hemisphere.-The mesial surface of the
hemisphere is marked off from both the convex supero-external and the tentorial
surface by the margin of the great longitudinal fissure. This margin follows a
curved course as a well-defined border from the posterior extremity of the gyrus
rectus as far as the occipital pole of the cerebrum. From this point it passes for-
wards and pursues a slightly curved course to the splenium of the corpus callosum
immediately beneath which it ends. The latter part is termed by Schwalbe the
internal occipital border; it is only seen in carefully-hardened brains, and appears
as a rounded margin crossing the lobulus lingualis, and in front of this marking
FIG. 411.-CONVOLUTIONS AND FISSURES ON THE MESIAL AND TENTORIAL SURFACES
OF THE HEMISPHERE.
PARACENTRAL LOBULE
SULCUS PARACENTRALIS
CALLOSO-MARGINAL FISSURE
MARGINAL CONVOLUTION
PRÆCUNEUS
PARIETAL
LOBE
SULCUS
SUBPARIETALIS.
PARIETO-
OCCIPITAL
FISSURE
CUNEUS
CALCARINE-
FISSURE
OCCIPITAL
LO B/E
LOBULUS/
LINGUALIS
INFERIOR OCCIPITO-TEMPORAL
CONVOLUTION
FRONTAL
LOBE
FALCIFORM LOBE
GYRUS
FORNICATUS
Isthmus
Collateral fissure
VEMPOR
DENTATE
FISSURE
NO DAL
FISSURE OF SYLVIUS
INCISURA TEMPORALIS
IMPRESSIO TENTORIAL UNCUS
PETROSA GROOVE
the gyrus fornicatus immediately above its isthmus (fig. 411). The tentorial
surface is marked off from the supero-external surface by a well-defined border
which extends from the occipital pole to the extremity of the temporo-sphenoidal
lobe, forming a slight curve with the convexity upwards. The fissural system of
the mesial and tentorial surfaces is of considerable importance and interest, as all
the complete fissures of the cerebrum appear on these surfaces. These fissures
are, as already mentioned, the internal parieto-occipital, the calcarine, the dentate,
and the collateral. The calloso-marginal, a constant and important incomplete
fissure, is also to be seen on the mesial surface.
The calloso-marginal fissure commences below the genu of the corpus callosum
and pursues a curved course parallel to the corpus callosum until it reaches a point
a short distance behind the upper extremity of the fissure of Rolando. It then
bends upwards and extends on to the convex surface for a short distance, where it
indents the upper end of the ascending parietal convolution. Two branches which
MESIAL AND TENTORIAL SURFACES OF HEMISPHERE
731
pass from this fissure deserve special mention as, although not constantly present,
they form useful lines of demarcation. One of these, the sulcus paracentralis,
passes upwards between the paracentral and the marginal convolutions. Another,
the sulcus subparietalis, passes backwards from the bend of the main fissure and
separates the præcuneus from the gyrus fornicatus.
The parieto-occipital fissure commences at the isthmus of the gyrus fornicatus,
and passes at first backwards and upwards, and then almost vertically upwards to
reach the margin of the hemisphere, where it bends outwards and ends as the
external parieto-occipital fissure.
The calcarine fissure commences by a bifid extremity near the occipital pole,
and passes horizontally forwards with a slightly curved course to become confluent
with the parieto-occipital fissure.
From what has been said, it follows that the internal parieto-occipital and calcarine
fissures form by their union a <-shaped figure. The hinder part of the stem of the and
the fore part of the calcarine fissure produce an elevation within the posterior cornu of the
lateral ventricle known as the hippocampus minor. It has been recently shown that in its
development the stem of the < may belong to the parieto-occipital fissure alone, or to the
calcarine alone, or may be common to both. (Cunningham.)
The callosal fissure is a deep furrow which follows the curve of the corpus callosum,
being placed between that body and the gyrus fornicatus. It commences below the
rostrum and terminates behind the splenium, where it becomes continuous with the
dentate fissure.
The dentate or hippocampal fissure extends from the splenium of the corpus
callosum to the hooked extremity (uncus) of the uncinate gyrus. It produces an
elevation in the descending cornu of the lateral ventricle, which is termed the
hippocampus major.
The collateral fissure is common to the occipital and temporal lobes. It passes
from a point on the under surface of the temporal lobe, near its apex, to the
occipital pole of the hemisphere. The reverse of this fissure appears as an elevation
(the eminentia collateralis) in the descending cornu of the lateral ventricle.
The following convolutions appear on the mesial and tentorial surfaces :-
The marginal convolution commences below the rostrum of the corpus callosum
and occupies the area of the mesial surface between the calloso-marginal fissure and
the margin of the hemisphere as far as the paracentral sulcus. The latter separates
it from the paracentral lobule. It is continuous around the margin of the hemi-
sphere with the olfactory, the internal orbital, and the superior frontal convolutions.
It is marked by tertiary fissures along its whole course, in particular by a fissure
which runs for some distance parallel to the calloso-marginal sulcus.
The paracentral lobule is bounded in front by the paracentral sulcus; below
and behind by the calloso-marginal fissure. It is continuous around the margin of
the hemisphere with the ascending frontal and ascending parietal convolutions;
but as it is connected with the former by a much broader band than with the latter,
it is referred to the frontal lobe. (Broca.)
When the typical backward turn of the upper extremity of the fissure of Rolando is
present, it hooks backwards into the forward bend formed by the upper extremity of the
calloso-marginal fissure, and thus the frontal and parietal lobes are only connected by a
narrow isthmus between the two fissures.
The gyrus fornicatus, or gyrus cinguli, commences between the rostrum of the
corpus callosum and the extremity of the marginal convolution, and, pursuing
an arched course parallel to the corpus callosum, ends in a narrow
lution, the isthmus, which connects it to the uncinate gyrus. It is placed
between the calloso-marginal and callosal fissures, and is thus clearly marked off
from adjacent structures in the greater part of its extent, but is often very

732
THE NERVOUS SYSTEM
imperfectly separated from the superior parietal lobule. It may also be connected
to the hinder end of the marginal convolution by a small gyrus crossing the calloso-
marginal fissure.
The præcuneus, or quadrate lobule, is a squarish mass of small gyri which is
continuous around the margin of the hemisphere with the superior parietal lobule.
It is bounded, in front by the upturned end of the calloso-marginal fissure; behind,
by the parieto-occipital fissure; and it may be marked off below, from the gyrus
fornicatus, by the sulcus subparietalis.
The cuneus, or cuneate lobule, is a wedge-shaped mass occupying the interval
between the internal parieto-occipital and calcarine fissures. It is continuous
around the margin of the hemisphere with the superior occipital convolution. In
a properly hardened right hemisphere it shows a distinct bevelling near the margin.
This is produced by the impression of the superior longitudinal sinus. This
bevelling can be traced downwards to the extremity of the lobulus lingualis, and less
distinctly forwards to the præcuneus. In rare instances it may be seen in the left
hemisphere instead of the right.
Two sagittally directed convolutions are situated on the tentorial surface. They
are termed the superior and inferior occipito-temporal convolutions. The superior
of these is divided into an anterior part called the uncinate gyrus, and a posterior
part which is known as the lobulus lingualis.
The uncinate convolution commences behind at the isthmus, by which it is
continuous with the gyrus fornicatus, and ends immediately behind the anterior
perforated space in a hook-like elevation, the uncus. It is separated from the
dentate convolution by the dentate fissure, and is marked off from the inferior
occipito-temporal convolution by the collateral fissure and, in front of this, by the
incisura temporalis. The outer part of the anterior end is marked by a distinct
groove, which, as it is produced by the free edge of the tentorium cerebelli, may be
called the tentorial groove (fig. 411).
The uncinate convolution is covered with a peculiar fine network of white fibres, the
substantia reticularis alba. These fibres are derived from the striæ longitudinales laterales
which pass from the splenium of the corpus callosum on to the isthmus, and from thence
to the uncinate gyrus.
The dentate convolution or fascia dentata will be more conveniently described with the
anatomy of the lateral ventricle, as it is usually dissected in connection with that cavity.
The lobulus lingualis is the posterior part of the superior occipito-temporal
convolution. It is bounded by the calcarine and parieto-occipital fissures above, and
by the collateral fissure below. As the internal occipital border crosses this lobule
it divides it into two parts, an upper part which appears on the mesial surface, and
a larger lower portion situated on the tentorial surface, and of indoor
The inferior occipito-temporal convolution extends from the apex of the
temporal lobe to the occipital pole of the hemisphere. It is bounded above by
the collateral fissure, and below by the inferior temporal and inferior occipital
fissures. It is marked by the impressio petrosa at the junction of its anterior and
middle thirds.
Three distinct impressions, which lie in a line with one another, are produced on the
brain by the petrous portion of the temporal bone. One of these (fig. 410, n) corresponds to
the portion of bone opposite the confluence of the superior petrosal with the lateral sinus.
Another, the impressio petrosa, which may be large and conspicuous, is caused by the
prominence of the superior semicircular canal. The third impression (incisura temporalis)
is situated near the vallecula Sylvii, about one-third of an inch external to the tentorial
groove.
FALCIFORM LOBE; LIMBIC LOBE.-The falciform lobe is the name proposed by Schwalbe
for the portion of the cerebral surface which cannot be satisfactorily relegated to any of the
five lobes above described. Its separation as a distinct lobe depends more upon considera-
tions based upon comparative anatomy and embryology than upon any indications afforded
FALCIFORM LOBE-CORPUS CALLOSUM
733

by the adult human brain. It is incompletely divided into two segments by the corpus
callosum. The outer segment (limbic lobe of Broca) is formed by the gyrus fornicatus and,
the uncinate convolution. These two convolutions, with the isthmus which unites them,
form a remarkable ring-like gyrus open only at the anterior perforated space. The inner
segment comprises the septum lucidum, the fascia dentata, and the fornix.
Of the remaining convolutions on the mesial and tentorial surfaces, the marginal and
paracentral belong to the frontal lobe; the præcuneus to the parietal lobe; the cuneus,
lobulus lingualis, and posterior portion of the inferior occipito-temporal, to the occipital
lobe; and the anterior part of the inferior occipito-temporal to the temporal lobe.
THE CORPUS CALLOSUM is a great white commissure which unites the cerebral
hemispheres. Its form can be well studied in a mesial section of the brain
(fig. 412). Here it is seen to form a longitudinal arch with rounded anterior and
FIG. 412.-MESIAL SECTION OF ENTIRE BRAIN. (After Henle.)
The (*) points to the anterior extremity of the gyrus fornicatus; above it is the basal
white commissure.

POSTERIOR
COMMISSURE
PINEAL BODY
SPLENIUM OF CORPUS
CALLOSUM
LAMINA
QUADRIGEMINA
AQUEDUCT
OF SYLVIUS
VALVE OF
VIEUSSENS
SULCUS OF MIDDLE
MONRO COMMISSURE
FORAMEN
OF MONRO
CALLOSAL FISSURE
SEPTUM LUCIDUM
ANTERIOR
COMMISSURE
CEREBELLUM
PITUITARY
BODY
FOURTH VENTRICLE MEDULLA
TUBER
PONS CORPUS
ALBICANS
CINEREUM
GENU
ROSTRUM
LAMINA CINEREA
SECOND NERVE
OPTIC COMMISSURE
posterior extremities. The posterior extremity is called the splenium; it is
rounded off behind and is formed by the corpus callosum doubling on itself, so
that a small portion is folded forwards under, and in close opposition to, the larger
part (fig. 413). The anterior extremity or genu is less sharply bent than the
posterior end. It is continued downwards and backwards into a portion which
appears pointed in section and is called the rostrum. The rostrum is connected
to the lamina cinerea by a thin layer of white substance, the basal white commissure.
The portion which intervenes between the splenium and rostrum, and which con-
stitutes the greater part of the corpus callosum, is called the body. The under
surface of the body is adherent behind to the fornix, and in front to the septum
lucidum. In coronal sections (figs. 415, 423) it can be seen that the under surface

734
THE NERVOUS SYSTEM
is free for some distance, except at its attachment in the middle line to the fornix
and septum lucidum. This free portion forms the roof of the lateral ventricles.
The upper surface remains free for a shorter distance than the lower, and ends at the
floor of the callosal fissure, where the fibres of the corpus callosum enter the sub-
stance of the hemisphere. It forms in the transverse direction a gentle curve with
the concavity directed upwards. Viewed from above, the corpus callosum is seen
to present a transverse striation, this being an indication of the bundles of fibres
passing from hemisphere to hemisphere. These transverse striations are crossed
superficially by narrow longitudinal bands, the striæ longitudinales and the striæ
longitudinales laterales or tæniæ tectæ.
The striæ longitudinales are placed one on each side of the middle line, and
lie very close together, leaving a narrow interval between them which is called the
raphe. Traced forwards, they slightly diverge and pass round the genu to the
FIG. 413.-A DISSECTION OF THE WHITE MATTER OF THE POSTERIOR PART OF
THE RIGHT CEREBRAL HEMISPHERE.
REDUPLICATED
PORTION OF SPLENIUM
(Viewed from the inner side. Schwalbe.)
SPLENIUM OF
CORPUS CALLOSUM
FORCEPS MAJOR
CORPUS
CALLOSUM
OPTIC-
THALAMUS
CORPUS
GENICULATUM
INTERNUM
TEGMENTUM
OCCIPITAL POLE
TAPETUM
CRUSTA
PULVINAR
FASCICULUS LONGITUDINALIS
INFERIOR
rostrum; here they separate more widely, and pass along the inner margin of the
anterior perforated space, under the name of the peduncles of the corpus callosum,
and are lost at the commencement of the fissure of Sylvius. If the striæ longi-
tudinales be traced backwards, they will be seen to diverge as they pass round the
splenium and join the forceps major on each side.
The tæniæ tectæ are placed on the upper surface of the corpus callosum under
cover of the gyrus fornicatus. They pass backwards over the splenium and spread
out on the isthmus of the gyrus fornicatus and on the uncinate convolution to form
the substantia reticularis alba. They are merely stray bundles of a system of
fibres (cingulum) which is contained within the gyrus fornicatus.
The fibres of the corpus callosum after entering the cerebral substance spread out to
every part of the hemispheres (with the exception of small portions of the temporal lobes)
in the following sets:-
The fibres from the genu pass forwards and outwards into the anterior part of the frontal
lobe, and then sweep inwards forming the forceps minor.

CORPUS CALLOSUM-LATERAL VENTRICLES
735
The fibres from the body have the following distribution :-The uppermost fibres pass
outwards and then upwards, and finally curve inwards to the upper and mesial surfaces of
the frontal and parietal lobes. The intermediate fibres pass transversely outwards to the
same lobes. The lowest fibres form the roof of the lateral ventricle, and are separated from
that cavity only by the ependyma and epithelium, and divide into anterior and posterior
sets which are differently distributed. The anterior set ends in the operculum. The
posterior set forms a layer called the tapetum which follows the descending and posterior
cornua of the lateral ventricle, roofing over and bounding these cornua externally. The
part which follows the descending cornu is destined for the temporal lobe. The portion
which accompanies the posterior cornu passes to the under part of the occipital lobe.
The fibres from the splenium, and from the part which is folded below it, pass backwards
and outwards, and then sweep inwards forming the forceps major, the fibres of which pass
to the posterior and upper parts of the occipital lobe.
Dissection. Having completed the examination of the corpus callosum and of the
mesial surface of the hemisphere, the student should next turn his attention to the lateral
FIG. 414.-DIAGRAMMATIC CORONAL SECTION OF THIRD AND LATERAL VENTRICLES.
(From Schwalbe, slightly modified.)
LATERAL VENTRICLE
CAUDATE
NUCLEUS
TENIA SEMI-
CIRCULARIS
Velum interpositum
00
Veins of Galen
Choroid plexuses of third
ventricle
-OPTIC THALAMUS
THIRD VENTRICLE
-TEGMEN
CRUSTA
The red lines indicate the epithelium.
ventricles. The remaining fibres of the body of the corpus callosum should be divided a
little to the right of the middle line and reflected outwards. This dissection will expose
the body and anterior cornu of the lateral ventricle. The posterior and descending cornua
should next be exposed by removing their outer wall.
THE LATERAL VENTRICLES are cavities in the "cerebral hemispheres which are
continuous with the third ventricle and with one another, through the foramen
commune anterius (page 738). They are roofed over, as already described, by the
corpus callosum, and are lined throughout by epithelium, which is reflected over the
choroid plexuses, and is not continuous with the lining of the third ventricle except
at the foramina of Monro. This epithelial lining forms the ventricular wall in
the region of the so-called transverse fissure, through which the choroid plexus
projects. This fissure is therefore not a breach in the ventricle, but simply a thin
part of the wall through which the locally thickened pia mater (choroid plexus)
can be seen. Each lateral ventricle consists of a central part or body and three
cornua: an anterior, an inferior or descending, and a posterior.

736
THE NERVOUS SYSTEM
The body may be defined as the portion of the ventricle which extends from
the foramen of Monro to the point where the cavity bifurcates into its posterior
and descending cornua. It corresponds almost exactly in length to the portion of
the optic thalamus which lies free within the ventricular cavity. It is greatest in
its antero-posterior, and smallest in its vertical diameter. It is limited on the inner
side by the attachment of the fornix to the corpus callosum, and by the narrow
posterior part of the septum lucidum. On the outer side it is bounded by the fibres
of the corpus callosum entering the substance of the hemisphere. Its floor looks
upwards and slightly inwards, as can be well seen in coronal sections, and is formed
by a series of structures which trend forwards with an inclination inwards. These
structures are placed in the following order from without inwards :-the caudate
FIG. 415.-CORONAL SECTION OF THE HEMISPHERES PASSING THROUGH THE
ANTERIOR CORNUA OF THE LATERAL VENTRICLES.
(From a mounted specimen in the Anatomical Department of Trinity College, Dublin.)
CORPUS
CALLOSUM
CAUDATE
NUCLEUS
INNER
CAPSULE
LENTICULAR
NUCLEUS
CLAUSTRUM
my
GREAT LONGI-
TUDINAL
FISSURE
ANTERIOR
HORN OF
LATERAL
VENTRICLE
SEPTUM
LUCIDUM
OLFACTORY TRACT-
GREAT LONGI-
TUDINAL
FISSURE
nucleus of the corpus striatum, the tænia semicircularis and lamina cornea, the
optic thalamus, the choroid plexus and the fornix (figs. 414 and 419).
The anterior cornu is directed forwards, downwards, and outwards. It appears
crescentic in outline both in coronal and horizontal section. The concavity of
the crescent looks downwards and outwards, and is caused by the projection of the
caudate nucleus into the cavity. The anterior cornu is bounded internally by the
septum lucidum, which forms a thin vertical partition between the anterior cornua
of opposite sides.
The posterior cornu is horizontal in its whole course, and is directed at first
backwards and outwards, and afterwards backwards and inwards. It presents on
its inner wall a curved prominence, the hippocampus minor or calcar avis; and
above this a second prominence, the bulb of the cornu, which is caused by a part
of the forceps major projecting into the cavity. The hippocampus minor is caused
by a fold of the cerebral wall, and corresponds to the calcarine fissure on the
mesial surface of the hemisphere (fig. 416). Its floor presents a slight elevation,
caused by the fasciculus longitudinalis inferior.
LATERAL VENTRICLES
737
Dissection. The operculum should next be pulled upwards, when the small portion of
substance still attaching it to the brain will be broken through. A complete view of the
island of Reil is then obtained. Lastly, the student should make a series of thin sagittal
sections through the island of Reil and the frontal lobe until the great transverse fissure
and its relation to the descending cornu of the lateral ventricle is seen (fig. 417). The
sections will pass through the lenticular and caudate nuclei of the corpus striatum and
through the optic thalamus.
The inferior or descending cornu pursues a more curved and complicated course
than the other two cornua. It is directed at first outwards and backwards, and
then bends somewhat sharply downwards; lastly, it sweeps forwards with an
inclination inwards, following the long axis of the temporo-sphenoidal lobe. In
2083
bioxodo
FIG. 416.-CORONAL SECTION OF THE HEAD PASSING THROUGH THE POSTERIOR
HORNS OF THE LATERAL VENTRICLES.
(From a mounted specimen in the Anatomical Department of Trinity College, Dublin.)

Dura mater-
BULB OF
POSTERIOR
CORNU
HIPPOCAM-
PUS MINOR
FASCICU-
LUS LONGI-
TUDINALIS
INFERIOR
Superior
longitudinal
sinus
Falx cerebri
Straight
sinus
POSTERIOR
CORNU OF
LATERAL
VENTRICLE
CALCARINE
FISSURE
Lateral sinus CORPUS DENTATUM Tentorium cerebelli
transverse section it is seen to be somewhat triangular, presenting a floor, an inner
wall, and a curved roof which bounds the cavity above and externally. The floor
is formed by the eminentia collateralis. The following structures appear on the
inner wall: the hippocampus major, ending in the pes hippocampi; the corpus
fimbriatum; and the choroid plexus, the latter apparently passing through a fissure
(the great transverse fissure). The roof is formed from within outwards by the
tænia semicircularis, by the narrow posterior prolongation of the caudate nucleus
of the corpus striatum, and by the tapetum. At the extremity of the cornu the
roof is formed by the amygdaloid tubercle. The tænia semicircularis and caudate
nucleus may be traced to this tubercle.
The eminentia collateralis is a smooth triangular elevation, which commences
in the interval between the hippocampus major and minor, and extends, narrowing
as it proceeds, nearly to the extremity of the descending cornu. It is the indenta-
tion of the ventricular wall produced by the collateral fissure.
The hippocampus major, or cornu Ammonis, is a curved white body which ends
in a blunt extremity (pes hippocampi), on which are small indentations, giving it

3 B

738
THE NERVOUS SYSTEM
an obscure resemblance to the paw of an animal. It corresponds to the dentate
fissure.
The corpus fimbriatum, tænia hippocampi, or fimbria, is a narrow strip of white
matter with a somewhat wavy appearance, which is placed along the concave side
of the hippocampus major. It is formed by a portion of the fibres of the fornix
continued into the descending cornu, and presents apparently a free edge towards
the transverse fissure, but is in reality continued into the epithelium which covers
the choroid plexus. When this epithelium is torn through and the choroid plexus
pushed forwards, the fascia dentata is exposed; the latter structure is placed in
the floor of the dentate fissure, between the fimbria and the uncinate gyrus.
The choroid plexuses are vascular fringes formed by an infolding of the pia
mater in the region of the so-called great transverse fissure. They extend from
FIG. 417.-A DISSECTION OF THE DESCENDING CORNU OF THE LATERAL VENTRICLE,
WITH A SAGITTAL SECTION THROUGH THE BASAL GANGLIA.
Choroid plexus
CAUDATE NUCLEUS
FORCEPS MAJOR
HIPPOCAMPUS MINOR
TENIA SEMICIRCULARIS
FIMBRIA
OPTIC THALAMUS-
CORPUS GENIC. INTERNUM
EMINENTIA COLLATERALIS
CRUS CEREBRI
FASCIA DENTATA
HIPPOCAMPUS MAJOR
FORNIX
OPTIC TRACT
CORPUS CALLOSUM
FORAMEN CAUDATE SEPTUM
OF MONRO NUCLEUS LUCIDUM
LENTICULAR NUCLEUS
CAUDATE NUCLEUS
the termination of the descending cornua to the foramina of Monro, through
which they disappear. The epithelial lining of the ventricle passes from the
thin (apparently free) edge of the fimbria over the choroid plexus to the tænia
semicircularis. This epithelium, which is the morphological wall of the cornu,
excludes the choroid plexus (strictly speaking) from the ventricular cavity.
The foramina of Monro are the apertures through which the lateral ventricles
communicate with the third ventricle, forming at their communication a Y-shaped
passage, the foramen commune anterius, by means of which the lateral ventricles
of opposite sides communicate with one another. The choroid plexuses of the
lateral ventricles are continuous with one another through this passage. Each
foramen of Monro is crescentic in outline, and is bounded in front and above by
the anterior pillars of the fornix; below and behind by the anterior extremity of
the optic thalamus; and behind by the reflexions of epithelium from the fornix
and optic thalamus on to the choroid plexus.

LATERAL VENTRICLES-BASAL GANGLIA
739
INTERNAL
PARIETO-
OCCIPITAL
FISSURE
FASCIOLA
CINEREA
The fascia dentata, or dentate convolution, is the free edge of the grey matter
of the hemisphere, and derives its name from its characteristically notched or
indented appearance. It is placed at the inner side of the dentate fissure, and
follows this fissure upwards towards the splenium of the corpus callosum, where it
becomes continuous with the fasciola cinerea. The fasciola cinerea is a grey lamina
resembling the fascia dentata but with a smooth margin. It ends just above the
splenium of the corpus callosum.
Dissection. The student should slice away the left hemisphere and expose the lateral
ventricle of that side, leaving the central portion of the corpus callosum in situ for the
FIG. 418.-A DISSECTION SHOWING THE FREE OR INTRAVENTRICULAR PORTION OF THE
CAUDATE NUCLEUS. THE MESIAL AND TENTORIAL SURFACES OF THE HEMISPHERE
ARE ALSO SHOWN.
(From a mounted specimen in the Anatomical Department of Trinity College, Dublin.)
EXTRAVENTRICULAR PART
OF OPTIC THALAMUS
SULCUS
CHOROIDEUS
CALCARINE
FISSURE
FIMBRIA-
FASCIA
DENTATA
CRUSTA
AMYGDALOID
TUBERCLE
CALLOSO-MARGINAL
FISSURE
CORPUS CALLOSUM
CAUDATE NUCLEUS
TENIA
SEMICIRCULARIS
VENTRICULAR PART
OF OPTIC THALAMUS
FORNIX
ANTERIOR
COMMISSURE
BUNDLE OF
VICQ D'AZYR
OLFACTORY TRACT
CORPUS ALBICANS
DENTATE
FISSURE
CORPUS GENICULATUM
INTERNUM
UNCUS
present. He should then make a series of horizontal sections through the island of Reil
and corpus striatum of the left side. If he has carried out the dissection as recommended
on the right side, he will now be in a position to study the corpus striatum both in hori-
zontal and vertical section, and at the same time to examine its intraventricular part more
fully. The horizontal sections will pass through both nuclei of the corpus striatum with
the inner and outer capsules, the claustrum, and a portion of the optic thalamus (fig. 419).
BASAL GANGLIA OF THE HEMISPHERES
A series of ganglionic masses is placed in the base of each cerebral hemisphere.
They are subjacent (with the exception of the amygdaloid nucleus) to the island of
Reil and form, with that lobe, the oldest part of the hemisphere; that is to
say, they constitute the portion which is (as already mentioned) the first to appear
both in the vertebrate series and also in the development of the individual. They
are all semi-detached local thickenings of the grey cortex, and may be enumerated
as follows:-the corpora striata, each composed of two nuclei, the nucleus caudatus
3B2
740
THE NERVOUS SYSTEM
and the nucleus lenticularis; the claustra, and the amygdaloid nuclei. The optic
thalami are in close proximity to the corpora striata, but belong to the thalam-
encephalon. Certain important fasciculi of white matter are intimately related
to the corpora striata. The chief of these white fasciculi are the inner and outer
capsules, the anterior commissure, and the tænia semicircularis.
The nucleus caudatus is an elongated mass of grey matter somewhat resembling
a pear with a long curved stalk. It presents a free, or ventricular, surface, and a
surface which is embedded in the hemisphere. It is thickest at the anterior end,
or head. The free surface of the anterior thickened portion looks upwards and
inwards, and bulges into the anterior horn of the lateral ventricle. From thence
it ascends with an inclination outwards to the body of the ventricle, where it forms
the outermost constituent of the floor of that cavity, and narrows into the com-
mencement of the tail. In this situation it is separated from the optic thalamus by
the lamina cornea and tænia semicircularis. The tail of the nucleus caudatus then
passes into the descending cornu. It is placed at first in front of the cornu, after-
wards forms part of the roof of that cavity, and ends at the amygdaloid tubercle.
The deep surface of the caudate nucleus is separated from the nucleus lenticularis
by a layer of white matter called the inner capsule. The two nuclei are, however,
connected by bands of grey matter which intersect the fibres of the anterior limb
of the inner capsule, and are directly continuous for a short distance in front.
The nucleus lenticularis is embedded in the substance of the hemisphere except
at the base of the brain, where it comes to the surface for a small part of its extent
at the anterior perforated space. Here it is continuous externally with the claustrum
and, as before stated, with the nucleus caudatus. In horizontal section it appears
like a bi-convex lens, with its surface directed outwards and inwards, the outer
surface forming a curve of larger radius than the inner. In sagittal section the
lenticular nucleus is also somewhat lens-shaped in outline (fig. 417). In coronal
sections through the anterior part it appears crescentic, with the convexity turned
downwards and outwards (fig. 415); but in successive sections taken from before
backwards the crescentic gives place to a triangular or wedge-shaped outline
(fig. 421). In fresh brains this grey mass can be seen to be traversed by thin
white intersections, the internal and external medullary laminæ, which divide
it into three zones. The middle and inner zones are of a yellowish grey colour,
and constitute the globus pallidus. The outer zone is of a darker reddish grey, and
is traversed with fine white striæ. It is called the putamen.
The putamen is the longest part of the lenticular nucleus, and is the only portion of that
body which is continuous with the caudate nucleus.
The above agrees substantially with the account which is given by Schwalbe; this
anatomist, however, describes the amygdaloid nucleus as discontinuous with the tail of the
caudate nucleus. According to Foster and Sherrington, the globus pallidus of the lenticular
nucleus as well as the putamen is continuous with the caudate nucleus.
A band of white fibres, the ansa lenticularis, passes inwards below the inner capsule.
It emerges from the under surface of the lenticular nucleus, being continued from the
medullary laminæ. It also receives fibres from the inner segment of the globus pallidus.
The ansa lenticularis enters the subthalamic region and passes beneath the red nucleus,
where it becomes indistinct.
The claustrum is a thin band of grey matter which is placed, nearly vertically,
external to the lenticular nucleus, and separated from the latter, except at its lower
part, by the outer capsule. It is separated from the grey matter of the island of
Reil by a layer of white matter, into which it sends small pointed processes
corresponding to the gyri operti of the island. It is fused at its anterior end with
the amygdaloid nucleus. (Hill.)
The amygdaloid nucleus is a thickening of the grey cortex of the apex of the
temporal lobe, and produces a bulging (amygdaloid tubercle) into the roof of the
extremity of the descending cornu of the lateral ventricle.
BASAL GANGLIA OF HEMISPHERES
741
The tænia semicircularis, or stria terminalis, is a band of fibres which passes
upwards and backwards from the anterior pillar of the fornix, and traverses the
groove between the caudate nucleus and the optic thalamus. It is reinforced by
some fibres from the anterior cornu of the lateral ventricle. It accompanies the
caudate nucleus into the roof of the descending cornu, and ends in the amygdaloid
nucleus. In its course along the groove above mentioned it is partly covered by
FIG. 419.-HORIZONTAL SECTION OF THE CEREBRUM.
(After Landois and Stirling.)

ANTERIOR CORNU
CAUDATE NUCLEUS
INNER CAPSULE.
(ANTERIOR LIMB)
OUTER CAPSULE-
LENTICULAR
NUCLEUS
CLAUSTRUM
INNER CAPSULE
(POSTERIOR LIMB)
OPTIC THALAMUS-
GYRUS FORNICATUS
CORPUS CALLOSUM
SEPTUM LUCIDUM
CORPUS STRIATUM
ANTERIOR PILLAR
OF FORNIX
TENIA SEMI-
CIRCULARIS
OPTIC THALAMUS
CORPUS GENICU-
LATUM INTERNUM
CAUDATE NUCLEUS-
HIPPOCAMPUS-
MAJOR
HIPPOCAMPUS
MINOR
IV
CORPORA QUADRI-
GEMINA
CLAVA
FUNICULUS CUNEATUS
FUNICULUS GRACILIS
SUPERIOR PEDUNCLE
OF CEREBELLUM
INFERIOR PEDUNCLE
MIDDLE PEDUNCLE
ALA CINEREA
OBEX
the vein of the corpus striatum and by a thickened band of ependyma, the lamina
cornea, which also covers the vein.
The inner capsule is a broad band of white fibres which is placed on the inner
side of the nucleus lenticularis. In horizontal section it presents an anterior limb
between the two nuclei of the corpus striatum, and a posterior limb which separates
the nucleus lenticularis from the optic thalamus. These two limbs meet at an
angle salient inwards. This angle is called the genu, and is placed adjacent to the
tænia semicircularis.
In vertical section the inner capsule presents a beautiful arched arrangement of radiating
white fibres (fig. 417).


742
THE NERVOUS SYSTEM
The outer capsule, much narrower than the inner, is a band of white fibres
which intervenes between the claustrum and the nucleus lenticularis.
In a horizontal section through the basal ganglia of the hemisphere and adjacent part
of the thalamencephalon, an alternation of grey and white layers is seen in the following
order from without inwards :-(1) the grey matter of the island of Reil; (2) the white
matter of the same lobe; (3) the claustrum; (4) the outer capsule; (5) the nucleus lenticu-
laris; (6) the inner capsule; (7) the nucleus caudatus and optic thalamus, separated from
one another by the tænia semicircularis (fig. 419).
The anterior commissure bounds the third ventricle in front, but belongs to the
cerebral hemispheres, as it is developed in connection with the lamina terminalis.
It presents a cylindrical free surface towards the third ventricle, where it appears
like a small transverse bar in the interval between the anterior pillars of the fornix.
It passes outwards in front of the fornix, and traverses the cerebral substance below
the lenticular nucleus on each side (fig. 421), the fibres inclining backwards
and assuming a twisted arrangement as it proceeds. It ends in the temporal lobe.
Dissection. The student should cut through the remaining part of the corpus callosum
about the middle, raise the posterior portion, carefully detaching it from the subjacent
fornix, and throw it backwards. This dissection will reveal the body and the diverging
posterior pillars of the fornix. He should then raise the anterior portion of the corpus
callosum, and snip through the septum lucidum with a sharp pair of scissors. The slit-like
fifth ventricle will now be visible, or may be brought into view by gently separating the
laminæ of the septum lucidum with the point of the scalpel. The fornix should next be
examined and then divided by cutting through its body and throwing the parts backwards
and forwards. By this dissection the so-called transverse fissure will be opened up and
the velum interpositum exposed.
The FORNIX is a longitudinally-arched bundle of fibres composed of two
symmetrical halves which are united together at the central part, forming the body,
but diverge in front and behind, constituting the anterior and posterior pillars.
The body forms a curve parallel to the corpus callosum, to the under surface of
which it is adherent.
It is narrowest and thickest in front, widest and thinnest behind. It lies on the
velum interpositum, which separates it from the third ventricle and from the optic
thalami. The outer portions of its upper surface are placed in the body of the
lateral ventricles, covered by the epithelium which passes at the thin outer margin
of the fornix into the epithelial covering of the choroid plexuses. The posterior
pillars diverge from the body, passing backwards and outwards. In the interval
between them the splenium of the corpus callosum can be seen if viewed from below.
This is marked by faint longitudinal, transverse, and oblique lines, and is described
as the lyre. The posterior pillars expand as they pass outwards and enter the
descending cornua of the lateral ventricles. A conspicuous bundle of fornix fibres
passes along the concave border of the hippocampus major as the fimbria, which
can be traced to the uncus. Other fibres are scattered over the hippocampus major
and the eminentia collateralis. The anterior pillars sweep downwards with a
sharper curve than the corpus callosum, and so diverge from it, leaving an interval
which is occupied by the septum lucidum. They descend, in the form of two
rounded slightly-diverging bundles, immediately behind the anterior commissure.
Here they are joined by the tæniæ semicirculares, and receive fibres from the
peduncles of the pineal body and from the septum lucidum. In this situation they
present a free surface, except in front, where they give attachment to the septum
lucidum. Having reached the base of the brain, they end in the grey nuclei of the
corpora albicantia.
The anterior pillars of the fornix were formerly described as twisting on themselves to
form bends or loops in the base of the brain, the corpora albicantia, the fibres after forming
the bend being continued upwards on the inner sides of the descending anterior pillars as

FORNIX-SEPTUM LUCIDUM
743
the bundles of Vicq d'Azyr. This description is borne out by macroscopic dissection, but it
has been shown that the bundles of Vicq d'Azyr are discontinuous with the fornix fibres.
(Forel and Gudden.)
The septum lucidum is formed by thin portions of the hemisphere walls, which
have become approximated and in part fused, but are separated in the greater part
of their extent by the fifth ventricle. It appears as two closely approximated thin
vertical laminæ, separating the anterior cornua of the lateral ventricles of opposite
sides. It is attached above and in front to the under surface of the body and back
of the genu of the corpus callosum, below to the rostrum and to the basal white
commissure, and behind to the anterior pillars of the fornix. Viewed from the
side, it is triangular in outline, with an acute angle directed backwards and occupy-
ing the narrow interval between the front of the body of the fornix and the corpus
callosum (fig. 412).
Each of the two lamine which constitute the septum lucidum contains three layers: a
layer of ependyma and epithelium next the lateral ventricle, a middle layer of white fibres,
and a layer of rudimentary grey matter next the fifth ventricle. A layer of connective
tissue immediately bounding the fifth ventricle (rudimentary pia-matral layer) is described
by Testut.
The fifth or Sylvian ventricle is a narrow, sagittally-directed, slit-like cavity
which originally formed a part of the great longitudinal fissure. It does not
communicate with any of the true ventricles of the brain.
The great transverse fissure of the cerebrum is of a horse-shoe shape, and extends from
the foramen of Monro on each side to the termination of the descending cornu of the lateral
ventricle. It is not a fissure in the sense of forming a communication between the
ventricles and the exterior of the brain, but it may be considered as a fissure in the same
sense that we use the term 'complete fissure.' If we compare it with the adjacent dentate
fissure, we find that the latter produces a bulging (the hippocampus major) into the
ventricular cavity. This bulging contains an inner layer of white and a outer layer of grey
matter, and is simply a fold of the ventricular wall, which is here thinner than elsewhere.
The floor of the dentate fissure is occupied by pia mater. Now if we suppose the substance
of the hippocampus thinned away until only the epithelial lining of the ventricle was left,
this epithelium would come in contact with the external pia mater, and an arrangement
resembling the choroid plexus, coming through a fissure, the hippocampal fissure, would be
produced. The choroid plexus is therefore an internal convolution reduced to a layer of
epithelium forming the morphological wall of the ventricle, and produced by a fissure,
the great transverse fissure, which is occupied by a specialised and highly vascular part
of the pia mater. In comparing the great transverse fissure with the complete fissures
of the cerebral hemispheres, however, we must not lose sight of the fact that it is not
limited to the hemisphere wall (except at its extremities in the temporal lobes), but is
produced, for the greater part of its extent, by the folding of the prosencephalon over the
thalamencephalon (page 709). According to Merkel and Mierzejewsky, small slit-like
apertures are found in the region of the transverse fissure near the termination of the
descending horn of the lateral ventricle. These place the cavity of the lateral ventricle in
communication with the subarachnoid space.
The velum interpositum, or tela choroidea superior, is a large triangular fold of
pia mater which overlies the third ventricle. The body and posterior pillars of
the fornix and the splenium of the corpus callosum rest on its upper surface. It
is continuous laterally with the choroid plexuses of the lateral ventricles, which are
simply the convoluted and highly vascular margins of the fold. Traced backwards,
the layers are seen to divaricate and to become continuous with the pia mater
covering the tentorial surface of the occipital lobes and the upper surface of the
cerebellum. Two large veins, the veins of Galen, commence at the anterior
extremity of the velum interpositum. The veins of Galen are chiefly formed by
the veins of the corpora striata, and are continued backwards in the middle line
to end in the straight sinus. In this course they lie in a prolongation of the
subarachnoid space between the two layers of pia mater which form the velum
interpositum, and usually unite into one vein before entering the straight sinus.




744
THE NERVOUS SYSTEM
The under surface of the velum interpositum rests on the inner parts of the optic
thalami, and between the latter it is placed directly over the third ventricle, where
it is covered by a layer of epithelium continuous with the lining of that cavity, but
discontinuous with the epithelium of the lateral ventricles, except at the foramina
of Monro.
The choroid plexuses extend from the extremity of the descending cornu of
each side to the foramen of Monro where they become continuous with one another
through the foramen commune anterius. From the junction of the two plexuses
FIG. 420. HORIZONTAL SECTION OF THE CEREBRAL HEMISPHERES.
(From a mounted specimen in the Anatomical Department of Trinity College, Dublin.)
(The fornix has been reflected to show the velum interpositum.)

CORPUS
CAUDATE-
NUCLEUS
ANTERIOR-
PILLARS OF
FORNIX
Veins of Galen-
POSTERIOR-
PILLARS OF
FORNIX
CALLOSUM (in
section)
-SEPTUM
LUCIDUM
FIFTH
VENTRICLE
TENIA SEMI-
CIRCULARIS
OPTIC
THALAMUS
Velum
interpositum
-Choroid plexus
FIMBRIA
HIPPOCAMPUS
MAJOR
EMINENTIA
Straight sinus-
CEREBELLUM
COLLATERALIS
HIPPOCAMPUS
MINOR
a pair of small vascular fringes pass backwards on the under surface of the velum
interpositum in the middle line, and depend into the cavity of the third ventricle,
constituting the choroid plexuses of that cavity (fig. 414). The posterior choroid
artery enters the choroid plexus at the termination of the descending cornu; other
smaller arteries are supplied to the plexus from behind, and are derived from the
posterior cerebral artery.
Dissection. The student should divide the splenium of the corpus callosum in the
middle line, and remove the portions of the hemispheres which lie posterior to the great
transverse fissure; they will readily separate at the fissure, and break off at the extremities
CHOROID PLEXUSES-THALAMENCEPHALON
745

of the temporal lobes. This operation should be conducted with gentleness, as the walls
of the third ventricle are very prone to become unduly divaricated by this dissection. The
part removed should be re-examined, as the relations between the fissures and hippocampi
can be studied to great advantage at this stage. The cavity of the third ventricle may now
be displayed by raising the velum interpositum, and reflecting it backwards. This must
be done cautiously, as the pineal body is closely enfolded in the posterior part of the under
layer of that membrane, and an attempt should be made to retain it in its proper place.
The dissector should thoroughly examine the cavity and floor of the third ventricle and
the free surfaces of the optic thalami, but is recommended to dissect the deep surfaces of
the latter bodies in connection with the mesencephalon.
THE THALAMENCEPHALON
The THIRD VENTRICLE is a narrow cavity whose lateral walls are so closely
approximated that in coronal sections it appears as a vertical slit. It communi-
cates in front with the lateral ventricles by the foramina of Monro. Behind, it
is continuous with the fourth ventricle through a narrow passage, the aqueduct of
Sylvius. The opening into the aqueduct is bounded above by a transverse white
bundle of fibres, the posterior commissure; and, above this, a prolongation of the
FIG. 421.-CORONAL SECTION THROUGH THE ANTERIOR PART OF THE THIRD VENTRICLE.
(From a mounted specimen in the Anatomical Department of Trinity College, Dublin.)

CORPUS CALLOSUM
SEPTUM LUCIDUM
ANTERIOR CORNU OF
LATERAL VENTRICLE
INNER
CAPSULE
OUTER
CAPSULE
ANTERIOR
PILLARS OF
FORNIX
ANTERIOR
COMMISSURE
THIRD
VENTRICLE
OPTIC TRACT
TEMPORAL LOBE
-CAUDATE
NUCLEUS
TENIA SEMI-
CIRCULARIS
OPERCULUM
-CLAUSTRUM
-PUTAMEN
-ISLAND OF
REIL
GLOBUS
PALLIDUS
ANTERIOR
COMMISSURE
AMYGDALOID
NUCLEUS
PITUITARY BODY
ventricular cavity extends into the stalk of the pineal body, in which it ends
blindly. The third ventricle is covered by the corpus callosum, the fornix, and the
velum interpositum; its true roof, however, is formed by the epithelium lining the
under surface of the last-named structure. The central part of its cavity is crossed
transversely by the middle or grey commissure. It is bounded, laterally by the
optic thalami, and in front by the anterior pillars of the fornix and by the anterior
commissure. It is limited behind by the commencement of the aqueduct of
Sylvius, by the posterior commissure, and by the reflexion of epithelium from the
upper surface of the pineal body on to the under surface of the velum interpositum.

746
THE NERVOUS SYSTEM closes
In the anterior part of the ventricle the floor is marked off from the lateral walls
by the anterior pillars of the fornix, which, after forming part of the anterior
boundary, sweep backwards with an inclination downwards: in this situation they
are covered by a thin layer of the central grey substance of the ventricle, and
project as slight ridges. The third ventricle is relatively shallow for about the
posterior third of its extent, but in its anterior two-thirds it presents a deep recess
which is divided into an anterior and a posterior part by a prominent ridge. This
ridge is formed by the junction of the tuber cinereum and the lamina cinerea
above the optic commissure. The floor is formed by the following structures :--
behind, by the tegmental portion of the diverging crura cerebri, and between them
by the posterior perforated space; in front of this by the corpora albicantia, the
tuber cinereum with the infundibulum and the lamina cinerea. The latter slopes
upwards to the anterior commissure, and is relegated by some anatomists to the
anterior wall instead of to the floor.
The central grey matter of the third ventricle is continuous behind with the grey matter
of the aqueduct of Sylvius, and passes in front into the basal grey commissure. It also
covers the lower parts of the internal surfaces of the optic thalami, and gives a thin
covering to the anterior pillars of the fornix and to the bundles of Vicq d'Azyr.
The optic thalami are a pair of large ganglia placed one on each side of the
third ventricle. Each optic thalamus is a short prismatic body whose long axis is
directed forwards and inwards. This axis is not straight, but is slightly curved
with its convexity upwards. The thalamus presents an anterior and a posterior
extremity or tubercle, and four surfaces: a superior and an internal which
are free, and an inferior and an external which are imbedded in the cerebral
substance. The anterior tubercle is a blunt rounded point which forms the
posterior boundary of the foramen of Monro. The posterior tubercle, or pulvinar,
is broader than the anterior, and is compressed from above downwards. It is
directed backwards and downwards; it is continued externally into the outer
geniculate body, and overhangs the inner geniculate body. It is placed above and
in front of the descending cornu of the lateral ventricle, but is separated from
the cavity of the latter by the choroid plexus. The superior surface shows a
slight convexity, more pronounced in the antero-posterior than in the transverse
direction. It is covered with a layer of white fibres. It presents a groove, the sulcus
choroideus, which underlies the free edge of the fornix, separated from the latter
only by the velum interpositum. This groove marks off an antero-external area,
wider in front than behind, which ends in the anterior tubercle and which forms
part of the floor of the lateral ventricle. Internal to the sulcus choroideus is a
larger area, which is covered by the fornix and velum interpositum. This area is
limited internally for about its anterior half by the stria pinealis, or peduncle of
the pineal body, a white bundle of fibres which runs along the sharp edge which
separates the superior from the median surface. The posterior part of this area
slopes gradually into the pulvinar. Between the superior surface and the posterior
part of the stria pinealis is a small triangular area, the trigonum habenulæ, which
is sunk below the level of the adjacent part of the thalamus. The internal
surface is nearly flat and bounds the cavity of the third ventricle, towards which
it presents a slight convexity. It is of a pale-grey colour owing to a thick layer
of ependyma covering the ganglionic substance, and is united to its fellow of the
opposite side by a broad band of grey matter, the middle or grey commissure
(commissura mollis). It is crossed at its lower margin by a groove, the sulcus of
Monro, which passes from the foramen of Monro to the commencement of the
aqueduct of Sylvius. The external surface rests against the fibres of the inner
capsule behind the genu, being separated from the nucleus lenticularis by the inner
capsule. The inferior surface is placed over the crus cerebri, on the tegmental
part of which it rests.



OPTIC THALAMI-PINEAL BODY
747

In coronal sections through the posterior part of the thalamus, the external surface is
seen to be separated from the inferior surface by a distinct angle; but in similar sections
through the anterior part the two surfaces pass into one another, the angle being rounded
off. The grey substance of the thalamus is indistinctly marked off into three nuclei:
an antero-superior, an external, and an internal. The largest part of the antero-superior
nucleus forms the anterior tubercle; the thinner portion passes backwards above and
between the other two nuclei; its shape has been not inaptly compared to that of the
caudate nucleus. A remarkable bundle of white fibres, the ansa lenticularis, passes below
the optic thalamus and inner capsule from the lenticular nucleus of the corpus striatum.

The pineal body (epiphysis cerebri or conarium) is a reddish-grey body about
the size of a cherry-stone. It has the form of a flattened cone, compressed from
above downwards. Its long axis is directed forwards and slightly upwards. Its
base is directed forwards and passes into a bilaminar stalk. Its superior surface
FIG. 422.-CORONAL SECTION THROUGH THE MIDDLE COMMISSURE OF THE
THIRD VENTRICLE. (Schwalbe.)

CAUDATE
NUCLEUS
CORPUS
CALLOSUM
FORNIX-
OPTIC
THALAMUS
THIRD
VENTRICLE
INNER-
CAPSULE
CORPUS.
ALBICANS
LATERAL
VENTRICLE
TENIA SEMI-
CIRCULARIS
LENTICULAR
NUCLEUS
OUTER CAPSULE
MIDDLE
COMMISSURE
ISLAND OF REIL
CLAUSTRUM
OPTIC TRACT-
AMYGDALOID
NUCLEUS
is covered by epithelium for the anterior two-thirds or three-fourths of its extent,
and bounds in part the cavity of the third ventricle. Its inferior surface rests in
the mesial groove between the superior quadrigeminal bodies, separated from the
latter by a fold of pia mater. The stalk of the pineal body is continuous by its
lower lamina with the posterior commissure. Its upper lamina passes into the
peduncle or stria pinealis, which passes at first outwards, and then forwards, along
the margin of the optic thalamus which separates the upper and mesial surfaces of
that body; it then crosses the floor of the foramen of Monro and joins the anterior
pillars of the fornix.
The recussus pinealis is a diverticulum from the cavity of the third ventricle, which
extends into the stalk and a short distance into the body of the conarium. Within the
pineal body, and in the adjacent part of the velum interpositum, a number of gritty particles
(acervulus cerebri, brain sand) are found. These particles consist chiefly of phosphate and
carbonate of calcium. The pineal body was formerly described as a gland (pineal gland)

748
130 THE NERVOUS SYSTEM
but is now known to be a rudimentary unpaired eye. This pineal eye lies close to the
surface in some of the lower vertebrates, and was probably functional at a former period. A
great parietal foramen in the extinct reptile Ichthyosaurus is strongly suggestive of a
functional pineal eye.
The posterior commissure is a transverse band of fibres which projects into the
posterior part of the cavity of the third ventricle. It contains fibres which connect
the optic thalami of opposite sides. It probably contains decussating fibres
derived from the fillet (page 782), from the posterior longitudinal bundles, and
from the brachia of the nates (page 751). It belongs, therefore, more to the
mesencephalon than to the thalamencephalon.
The subthalamic tegmental region and the corpora geniculata will be more conveniently
described with the mesencephalon.
FIG. 423.-CORONAL SECTION THROUGH THE THIRD VENTRICLE BEHIND THE
MIDDLE COMMISSURE. (Gegenbaur.)
CORPUS CALLOSUM
FORNIX
OPTIC THALAMUS-
MIDDLE COMMISSURE
-CAUDATE NUCLEUS
LATERAL VENTRICLE
CLAUSTRUM
LENTICULAR
SUBSTANTIA NIGRA-
CRUSTA.
NUCLEUS
RED NUCLEUS
FIMBRIA
The basal grey commissure is a continuous plate of grey matter which is
formed from behind forwards by the posterior perforated space, the tuber cinereum,
and the lamina cinerea.
The posterior perforated space is a stratum of grey matter which is perforated
by a number of small vessels derived from the commencements of the posterior
cerebral and superior cerebellar arteries. It occupies the back part of the inter-
peduncular space and extends for a short distance under cover of the pons, where it
bounds a recess, the foramen cæcum anterius. It is continuous laterally with the
grey matter of the tegmenta of the crura cerebri, and is attached in front to the
corpora albicantia. The portion of the space which is situated in front of the exit
of the third nerve forms part of the floor of the third ventricle; the posterior part
belongs to the mesencephalon.
The corpora albicantia appear as a pair of white knobs in the base of the brain.
Each contains in its interior a grey nucleus. This nucleus is joined by the anterior
pillar of the fornix and the bundle of Vicq d'Azyr of the same side. The bundle
of Vicq d'Azyr passes upwards and forwards through the grey matter of the optic
thalamus to the anterior tubercle of that body.
The tuber cinereum is a grey elevation placed immediately behind the optic
BASAL GREY COMMISSURE
749
commissure. It is the largest part of the basal grey commissure, and is continuous
laterally, above the optic tracts, with the grey cortex of the temporal lobes (fig. 421).
In front it passes over the optic commissure into the lamina cinerea. It is
continued below into a conical process, the infundibulum, which is directed down-
wards and slightly forwards, through the minute central opening in the diaphragma
sellæ to end in the posterior lobe of the pituitary body. The upper part of the
infundibulum is hollowed out by a diverticulum of the third ventricle, the recessus
infundibuli. The tuber cinereum and infundibulum correspond to the median
recess in the floor of the third ventricle.
The pituitary body, or hypophysis cerebri, is a small ellipsoidal body which
is lodged in the pituitary fossa of the sphenoid bone. Its long axis is directed
transversely, and its antero-posterior and vertical diameters are about equal.
The pituitary body consists of two distinct lobes, an anterior and a posterior. The anterior
lobe is of a reddish-grey colour, and is considerably larger than the posterior lobe, which it
partially embraces. The posterior lobe, of a yellowish-grey colour, is lodged in a recess in
the anterior lobe, and is the only part connected with the infundibulum.
This body was formerly described as the pituitary gland, because it was supposed to
secrete the pituita, or mucus of the nose. According to Gaskell's ingenious theory, the
infundibulum is the mouth of an archaic alimentary canal. The ventricular system of the
brain is the rudiment of the cephalic stomach as found in Arthropods. The central canal
of the spinal cord is the archaic intestine, and the neuro-enteric canal (an embryonic com-
munication between the neural tube and the intestine) connects this archaic intestine with
the ano-rectal region. The pituitary body is of great interest in the light of this theory, as
it brings the archaic mouth to the surface. The posterior lobe is developed in connection
with the brain, but the anterior lobe is formed independently. It originates as an upward
growth of the epiblastic invagination which forms the mouth, and is afterwards cut off from
the pharynx by the chondrification and subsequent ossification of the skull.

The optic commissure is formed by the union and partial decussation of the
optic tracts of opposite sides. Each optic tract may be traced backwards from the
commissure, around the crus cerebri, to the region of the corpora geniculata
(page 752).
The lamina cinerea is a thin plate of grey matter which may be seen from
the base of the brain by pulling the optic commissure slightly backwards. It is
continuous in front with the grey matter of the olfactory convolutions of the
frontal lobes, and between the latter it is connected to the rostrum of the corpus
callosum by the basal white commissure. Laterally, it is continuous with the
anterior perforated space. It forms the anterior sloping part of the floor of the
third ventricle.
Dissection. The student should remove the pia mater from the anterior part of the
upper surface of the cerebellum, and also any of that membrane which may be still adherent
to the quadrigeminal bodies. The anterior part of the cerebellum should now be gently
pushed backwards until the quadrigeminal bodies and the lateral parts of the crura cerebri
are fully exposed. The valve of Vieussens and the slender pair of fourth nerves which
spring from its upper part are very liable to injury at this stage. In conducting this
dissection, the student will notice a pair of broad white bands, the superior peduncles of
the cerebellum, converging towards the lower pair of quadrigeminal bodies, and a thin
white lamina, the valve of Vieussens, filling the interspace between them. The mesen-
cephalon is now fully exposed, and its free surface should first be examined. Directions
will be subsequently given for the examination of its internal structure.


THE MESENCEPHALON
The aqueduct of Sylvius is a narrow passage which unites the cavities of
the third and fourth ventricles: hence it is sometimes called iter e tertio ad quartum
ventriculum. It is roofed by a plate of grey matter, the lamina quadrigemina,
which is surmounted by two pairs of elevations, the corpora quadrigemina. Its
floor is formed by the tegmenta of the crura cerebri. Its outline in transverse
750
THE NERVOUS SYSTEM
section varies in different parts of its course. Thus, at its commencement, under
the posterior commissure, it has the form of an isosceles triangle with the apex
directed downwards. Below the anterior quadrigeminal bodies it is heart-shaped,
then somewhat shield-shaped. Lower down, on the level of the posterior corpora
quadrigemina, it has the form of an ovate leaf with the stalk directed downwards;
and finally, at its junction with the fourth ventricle, it is T-shaped in section
(fig. 443).

Fig. 424.-DEEP ORIGIN OF THE THIRD NERVE. (After Krause.)
ऊ
CRUSTA
AQUEDUCT OF SYLVIUS
-DESCENDING
ROOT OF
TRIGEMINAL
NERVE
NUCLEUS OF
THIRD NERVE
POSTERIOR
LONGITUDINAL
BUNDLE
SUBSTANTIA
NIGRA
RAPHE
THIRD NERVE
The grey matter of the aqueduct is a thick stratum which surrounds that canal, and
is continuous with the grey matter of the floor of the fourth ventricle. It is bounded
below by the formatio reticularis, and by the posterior longitudinal bundle (fig. 443). It is
continuous above with the grey matter of the lamina quadrigemina. Groups of cells are
embedded in this grey substance; the most important of these is a long column of nerve-
cells which is placed near the middle line beneath the aqueduct close to the formatio
reticularis (fig. 424). This is the continuous nucleus of the third and fourth nerves.
commences near the junction of the third ventricle and the aqueduct, and extends for
nearly the whole length of the latter. It is on a line with the nuclei of two nerves (sixth
and twelfth) which arise from the floor of the fourth ventricle. The nucleus of the
descending root of the fifth nerve is a group of cells in the region of the upper quadrigeminal
It
CORPORA QUADRIGEMINA
751
bodies, situated above and external to the nucleus of the third nerve; it is limited on its
outer side by the white fibres of the nerve-root itself.
The formatio reticularis will be described with the anatomy of the medulla and pons.
The CORPORA QUADRIGEMINA are four greyish elevations which surmount the
lamina quadrigemina. The superior or anterior pair are termed the nates; the
inferior or posterior pair, the testes. The corpora quadrigemina are marked off by
FIG. 425.-LATERAL VIEW OF MESENCEPHALON, PONS, AND MEDULLA. (Gegenbaur.)

CORPUS GENICULATUM
EXTERNUM
CRUSTA
PULVINAR OF OPTIC
THALAMUS
PINEAL BODY
CORPUS GENICULATUM
INTERNUM
CORPORA
QUADRIGEMINA
FILLET
PONS
OLIVARY BODY
MIDDLE CEREBELLAR
PEDUNCLE
INFERIOR CEREBELLAR
PEDUNCLE
a cruciform groove, the transverse limb of which is the more distinct. The portion
of the vertical groove which lies between the nates is also well marked, but the
groove between the testes is shallow and is obscured by a rounded bundle of
fibres, the frenulum veli, which passes downwards and spreads out on the valve
of Vieussens, immediately below the testes. The corpora quadrigemina consist of
grey matter overlaid by a thin superficial stratum of white fibres.
The nates are broader and darker in colour than the testes, and form a pair of
ovoid elevations with their long axes directed upwards and outwards; this direction
is continued into the corresponding brachia.
The brachia of the nates, or superior brachia, are slightly-raised white bands
which pass on each side from the nates in the intervals between the pulvinar of the
optic thalami and the corpora geniculata interna. They are sharply marked off
from the latter, but less distinctly from the thalami. Each brachium is continued
below the corpus geniculatum externum of its own side directly into the optic tract.
The testes are lighter in colour, and form more pronounced elevations than the
nates. Each testis is a somewhat pear-shaped body, the narrow end of which is
continued into the brachium of its own side.
The brachia of the testes, or inferior brachia, are narrower and more prominent
than the brachia of the nates, and run parallel to the latter. Each brachium
passes below the corpus geniculatum internum of its own side and disappears from
the surface.
The corpus geniculatum internum is an oval elevation which is placed behind
the lateral groove of the mesencephalon under cover of the pulvinar. Its long axis
is directed transversely. A band of white fibres is prolonged from its outer end
into the optic tract. This passes as the hindermost layer of fibres in the optic
752
THE NERVOUS SYSTEM
commissure into the corresponding bundle of the opposite side. It is therefore
commissural in nature. It does not contribute any fibres to the optic nerve.
The corpus geniculatum externum is a slight elevation at the outer side of the
pulvinar. It is directly continuous with the optic tract.
The remainder of the mesencephalon is formed by the crura cerebri, each of
which is divided into three distinct parts easily recognised in transverse section
(fig. 424). These are (1) a greyish upper portion, the tegmen; (2) a band of almost
black substance, the substantia nigra; and (3) a lower white portion, the crusta,
which appears at the base of the brain. The tegmen is also marked off super-
ficially from the crusta by two grooves, the oculo-motor and the lateral groove,
which may be seen in section to correspond with the inner and outer extremities of
the substantia nigra. The oculo-motor groove derives its name from the third or
oculo-motor nerve, the filaments of which reach the surface along this furrow. The
lateral groove of the mesencephalon is best marked near the upper border of the
pons, where it is bounded below by the superficial fibres of the crusta; and above
by a triangular band of fibres, the fillet, which disappears under the testis and its
brachium.
The crusta, or pes, is a large flattened band of white fibres which is crescentic in
section, with the concavity directed backwards and inwards, and in contact with the
substantia nigra. Its antero-inferior, inner, and outer surfaces are free. These
surfaces are marked with ridges indicating the bundles of fibres of which it is
composed. These ridges do not run parallel to the axis of the crus, but take a
slightly curved course, passing at first outwards and then upwards. The crusta is
continuous below through the pons with the pyramidal body of the same side, and
with the cerebellar hemisphere of the opposite side. It is somewhat constricted
where it emerges from the pons. It is continuous above with the inner capsule.
Dissection. The student should scrape away the remains of the lenticular nucleus on
the left side until the white substance of the inner capsule is exposed. He should then
raise the superficial fibres of the under surface of the crus of the same side, and by tearing
off these fibres in an upward direction he may readily demonstrate the continuity of the
crusta with the inner capsule. The dissector may also follow the fibres of the crusta
downwards to the pyramidal bodies by cutting through the superficial transverse fibres of
the pons, but it is better to defer this dissection till a later period. The remainder of the
mesencephalon with the optic thalami should be carefully preserved until the end of the
dissection of the brain, when they should be examined in connection with the medulla and
pons by a series of sections.
The fibres composing the central third of the crusta are derived from the pyramidal
bodies and pass into the anterior half of the posterior limb of the inner capsule to the
ascending frontal and ascending parietal convolutions. Its outer third is formed by fibres
which are derived from the cerebellar hemispheres of the opposite side, and which pass
through the posterior half of the posterior limb of the inner capsule to the temporal and
occipital lobes. These fibres are considered to be sensory in function. Lastly, the fibres
constituting its inner third pass upwards through the genu and anterior limb of the capsule
to the convolutions of the frontal lobe, while below some form communications with the
nuclei of the cranial nerves, and others are distributed to the cerebellum in a similar
manner to the fibres of the outer third of the crusta. There are other tracts of minor
importance in the crusta.
The tegmental portions of the crura cerebri, unlike the crustæ, are continuous
with one another across the middle line, where they unite in a median raphe.
Each tegmen extends into the thalamencephalon below the optic thalamus, where
it contains a yellowish-grey lenticular body which is called the subthalamic
body. The tegmentum contains both grey and white matter, with a continuation
of the formatio reticularis of the medulla and pons. The most conspicuous of
the collections of grey matter is the tegmental or red nucleus, a mass of brownish-
grey matter which is placed below the optic thalamus, and extends backwards
into the mesencephalon below the aqueduct. It appears round in coronal sections
(fig. 423).

MESENCEPHALON-EPENCEPHALON
753
The best marked of the white strands are the superior peduncles of the cere-
bellum, the fillet, and the posterior longitudinal bundle (fig. 444). The filaments of
origin of the third nerve, passing from its nucleus through the tegmentum and inner
part of the substantia nigra, are also conspicuous in sections (fig. 443).
The superior cerebellar peduncle is readily distinguishable in sections through
the lowest part of the mesencephalon as a white, crescent-shaped bundle with its
inner or concave side bounded by the grey-coloured formatio reticularis which
separates it from the grey matter of the aqueduct. Higher up it takes a deeper
course below the floor of the aqueduct, and decussates with its fellow of the opposite
side. It then passes into the subthalamic region, and separates into an inner and
an outer division. The inner division passes internal to the red nucleus and enters
the under surface of the optic thalamus. The outer division passes external to the
red nucleus and probably enters the globus pallidus of the lenticular nucleus.
Fibres have been described as passing from the red nucleus to the cerebral cortex.
The fillet appears as a flattened bundle considerably smaller than the cerebellar
peduncle, and is placed below and external to the latter. It passes obliquely
upwards and outwards, and reaches the surface, appearing as a triangular band of
fibres before noticed. It winds round the superior cerebellar peduncles, and dis-
appears, for the most part, under the testis of the same side. Part of it is said to
ascend in the formatio reticularis and decussate with the fibres of the opposite side,
the foremost part of this decussation appearing as the posterior commissure which
has been described in connection with the third ventricle.
The posterior longitudinal bundle is a flattened bundle of fibres, thinner
externally than internally, which is placed between the formatio reticularis and
the grey matter of the aqueduct. It probably connects the nuclei of the nerves
(third, fourth, and sixth) which supply the muscles of the eye.
THE EPENCEPHALON
Dissection. The pia mater should be removed from the superior and inferior surfaces
of the cerebellum; care should be taken, however, in removing it from the inferior vermi-
form process. In dissecting the latter region, the membranes should be clipped close with
scissors rather than pulled out, as by the latter method the choroid plexuses of the fourth
ventricle would be removed and the fragile posterior medullary velum would be torn.
The student should examine first the upper and then the lower surface of the cerebellum,
but he should defer the study of the anterior parts of the inferior vermiform process (pyramid
and nodule) until the fourth ventricle is opened.
The CEREBELLUM consists of two lateral masses, the hemispheres, which are
united by a narrower median portion, the vermiform process. This is seen in
sagittal section in fig. 427. This median portion is but slightly raised above the
level of the hemispheres as seen from above, where it constitutes the superior
vermiform process (fig. 427); but, as seen from below (inferior vermiform
process), it forms the roof of a deep recess between the hemispheres, the vallecula,
which is occupied for the most part by the medulla. The vallecula terminates in
front at the cavity of the fourth ventricle. Behind, it passes into a deep notch, the
incisura marsupialis, which is occupied by the falx cerebelli and the cisterna
magna of the subarachnoid space. The surface of the cerebellum is covered by a
number of folia, which are curved, with a general direction convex backwards and
outwards. The folia are much narrower than the cerebral convolutions, and are of
a darker grey colour than the latter. They are separated by fissures, some of which
appear on the surface separating individual folia; others dip in for some distance
below the surface, and within these secondary fissures are developed. In this way
the great horizontal fissure and the interlobar fissures are formed. The separation
into lobes is somewhat arbitrary, as fissures resembling the interlobar fissures in
character traverse the substance of the lobes.



3 C

754
MORE THE NERVOUS SYSTEM
The cerebellum is connected to the adjacent parts of the cerebro-spinal axis by
three pairs of peduncles: a superior pair to the cerebrum; a middle pair to the
pons; and an inferior pair to the medulla.
The great horizontal fissure is deeper than the interlobar fissures. It com-
mences at the point where the middle peduncle of the cerebellum enters the hemi-
sphere and pursues a curved course around the margin of the hemisphere, inclining
first downwards, and then curving slightly upwards, and crossing the middle line
immediately above the incisura marsupialis, to pursue a similar course on the
opposite side. On opening up the fissure, numerous folia are seen to run obliquely
within it, some of which cross the floor of the fissure so as to connect the upper
and lower surfaces which bound the fissure. The great horizontal fissure separates
the superior and inferior surfaces of the cerebellum.
The superior surface of the cerebellum has a general inclination backwards
and outwards. This surface is approximately flat, but shows a slight concavity
corresponding to the superjacent occipital lobe of the cerebrum. Mesially the slope
of the surface becomes more abrupt, and forms the superior vermiform process.
Of the fissures which traverse this surface the most important is the sulcus cerebelli
superior, which branches off from the great horizontal fissure at its commencement
and curves over the posterior part of the upper surface to approach the great
horizontal fissure again at the superior vermiform process, where the two fissures
are separated only by a narrow band, the folium cacuminis (fig. 427). The sulcus
cerebelli superior divides the superior surface into a larger anterior part, the
quadrate lobe, and a smaller semilunar posterior portion, the posterior superior
lobe. Another fissure divides the quadrate lobe into an anterior crescentic and a
posterior crescentic portion. The anterior crescentic portion is usually subdivided
into two portions by another sulcus parallel to the fissure last mentioned.
The superior vermiform process is divided by fissures, continuous with the sulci
above described, into parts which are placed in the following order from before
backwards: lobulus centralis, monticulus cerebelli, and folium cacuminis. The
lobulus centralis is a small squarish mass which is placed below and behind the
testes, separated from the latter by a fold of pia mater. It rests below on the
lingula, which separates it from the valve of Vieussens (fig. 426). It expands
laterally into a pair of somewhat triangular folds, the alæ (fig. 426), which are
entirely overlapped and hidden by the quadrate lobes when the cerebellum is viewed
from above in its undisturbed position. The lingula is a small tongue-shaped
portion of the cerebellum which lies on, and is adherent to, the valve of Vieussens.
Its basal part is continuous with the lobulus centralis, and it consists of from
four to five transverse folia. The monticulus cerebelli is divided into an anterior
elevated portion, the culmen, and a posterior sloping part, the declive. The culmen
connects the anterior crescentic portions of the quadrate lobes of opposite sides, and
is traversed by the fissures which intersect these portions. The declive connects the
posterior crescentic portions, and consists of about six or seven transverse folia.
The folium cacuminis is a narrow band which connects the posterior superior lobes
of opposite sides. It is not a simple folium, but is marked on its superior and
inferior surfaces by transverse furrows.
The inferior surface of the cerebellum shows a pronounced convexity corre-
sponding to the inferior fosse of the occipital bone on which it rests. It is smoothly
rounded off externally and behind, but changes its direction abruptly internally and
in front, where it comes in contact with the medulla and pons. It is marked off
into lobes, which are arranged in the following order from behind forwards: pos-
terior inferior, slender, biventral, tonsillar, and flocculus. The posterior inferior is
a narrow crescentic lobe, which bounds the great horizontal fissure inferiorly. The
slender (lobulus gracilis) is similar in shape, but narrower, as its name implies.
The biventral, shorter and thicker than the two last described, is divided by a

EPENCEPHALON
755
well-marked fissure into an anterior and a posterior portion. The tonsillar lobe
(amygdala) lies internal and slightly anterior to the biventral, and is partly hidden
in the vallecula. The flocculus is a small lobe forming a marked projection in front
of the biventral lobe, which it separates from the middle peduncle of the cerebellum.
The inferior vermiform process is formed by the following parts, taken in order
from behind forwards: tuber valvulæ, pyramid, uvula, and nodule. The tuber
valvulæ is a transverse band, consisting of about seven or eight folia, which
connects the posterior inferior and slender lobes with their fellows of the opposite
side. The pyramid is the most massive portion of the inferior vermiform process,
and is connected to the biventral lobes on each side. It consists of from five to
eight folia. The uvula is an elongated portion, compressed laterally, and connected
to the amygdala on each side by the furrowed band. The nodule, or laminated
tubercle, is the prominent anterior extremity of the inferior vermiform process

FIG. 426.-INFERIOR SURFACE OF THE CEREBELLUM.
(From a mounted specimen in the Anatomical Department of Trinity College, Dublin.)
MIDDLE
PEDUNCLE
FLOCCULUS.
FOURTH
VENTRICLE-
BIVENTRAL
LOBE
UVULA
PYRAMID-
SLENDER-
LOBE
POSTERIOR-
INFERIOR
LOBE
LOBULUS CENTRALIS
VALVE OF VIEUSSENS
ALA
SUPERIOR PEDUNCLE
POSTERIOR
CRESCENTIC
LOBULE
SULCUS
CEREBELLI
SUPERIOR
NODULE
-AMYGDALA
TUBER
VALVULE
INCISURA
MARSUPIALIS
which projects into the cavity of the fourth ventricle. It is connected to the flocculus
on each side by a thin white plate, the inferior medullary velum. The latter will
be referred to in connection with the anatomy of the fourth ventricle.
Dissection. The student should now obtain a view of the principal systems of fibres in
the cerebellum by the following dissection, which we shall speak of as Reil's method. The
great horizontal fissure should be opened up and the portion of the cerebellum which lies
superior to that fissure gently torn off the underlying portion. If this proceeding has been
successfully accomplished, a large bundle of fibres will be seen passing through a gap
between the superior and middle peduncles of the cerebellum, and passing towards the
superior surface. This bundle is formed by the restiform body and by the lower fibres of
the pons. The position of the corpus dentatum will also be noticeable near the middle
line, as the white fibres which form the capsule of that body are disposed in ridges corre-
sponding to the plications of grey matter of the nucleus. A more superficial dissection on
the opposite side will show the fibres of the above-mentioned bundle passing inwards,
forming at first curves convex backwards, and then sweeping upwards into the folia of the
superior vermis. A horizontal section through the corpus dentatum on the right side will
expose the plicated bag of grey matter which constitutes the nucleus, an opening into
which, the hilum, will be seen on the inner and upper side. If a small portion of the
fibres of the superior peduncle of the cerebellum of the same side be now raised and torn
gently in a downward direction, the fibres are readily traceable into the white centre of
the nucleus.
302
756
THE NERVOUS SYSTEM
A horizontal section through the superior vermis will show the smaller nuclei of the
cerebellum (nuclei fastigii, emboliformis, and globosus). These are, however, somewhat
difficult to find. Lastly, a median sagittal section will expose the fourth ventricle, to obtain
a good view of which the remainders of the cerebellar hemispheres should be drawn gently
aside. In doing this care should be taken of the inferior medullary velum.

White matter of the cerebellum.-The course of the nerve-fibres in the cerebel-
lum will be dealt with further on page 783, but the appearance presented by the white
matter as seen in sections will now be described. In a mesial sagittal section of
the cerebellum (fig. 427) the amount of white matter is smaller in proportion to
the grey matter than in any other section. It presents a characteristically branched
appearance which is called the arbor vitæ. Two main divisions, the vertical and
horizontal branches, of the arbor vitæ are described, and from these secondary
ramifications arise. The vertical branch is mainly continued into the culmen,
where it subdivides somewhat freely. It sends forwards usually two branches into
the lobulus centralis, and a slender twig into the lingula. The main axis of the
horizontal branch is prolonged into a slender white band, which enters the folium
cacuminis. From the upper surface of the horizontal branch a stout offset is sent
into the declive, and from its lower surface branches are sent into the tuber valvulæ,
pyramid, and uvula. A small offset enters the nodule, and if this be traced in a
lateral direction it will be found to be continued into the inferior medullary velum.
In coronal sections the disposition of the white matter in the hemispheres is well
seen. It forms a somewhat ovoid mass in each hemisphere, near the centre of
which the corpus dentatum is placed (fig. 416). The appearance is very similar in
sagittal sections through the centre of a hemisphere. It is not necessary to give a
separate description of the divisions of the white matter, as these correspond to the
lobulation of the surface.
The grey matter in the interior of the cerebellum consists of four pairs of
nuclei, which are everywhere separated by white matter from the grey matter of
the folia. The largest of these nuclei in each hemisphere is called the corpus
dentatum. The smaller, which are placed nearer the middle line, are called the
nucleus emboliformis, nucleus globosus, and nucleus fastigii.
The corpus dentatum is a crumpled sheet of grey matter which presents a similar
outline in coronal, sagittal, and horizontal sections. This outline is approximately
an oval bounded by a wavy line. This line is broken only on the inner and anterior
side, where the white matter of the exterior is continuous with that of the interior
through an aperture called the hilum.
The nucleus emboliformis is an elongated streak of grey matter, which is
placed on the inner side of the corpus dentatum. It is somewhat enlarged at its
anterior extremity, hence it may be described as club-shaped. The nucleus glo-
bosus consists of several spheroidal clumps of grey matter, which are placed on the
inner side of the preceding; these clumps are connected with one another, and also
with the nucleus emboliformis and nucleus fastigii. The nucleus fastigii varies
somewhat in its minute structure from the three nuclei above described. It is
situated immediately over the roof of the fourth ventricle, separated from that
cavity, however, by a thin stratum of white matter. The nuclei of opposite sides
nearly touch one another in the middle line.
The FOURTH VENTRICLE is a cavity which is widest and most lofty about its
centre, and narrowed at its anterior and posterior extremities. It communicates
with the third ventricle in front through the aqueduct of Sylvius, and passes
behind into the central canal of the spinal cord. Its long axis is directed upwards
and forwards. The structures which bound it behind and above are said to
constitute its roof, while the parts bounding it below and in front are described as
its floor. The roof is formed from before backwards by the following structures :
the superior peduncles of the cerebellum with the valve of Vieussens between them,


FOURTH VENTRICLE
757
the inferior medullary vela, and the epithelial lining of the choroid plexuses and
tela choroidea inferior. Some small plates of white matter, the obex and the
ligulæ, also enter into the formation of the roof. The posterior part of the floor is
formed by the medulla and rather more than the anterior half of the upper surface
of the pons. Some white lines (striæ acustica), which cross the floor transversely,
approximately separate the pontine from the medullary portion of the floor. zal
The valve of Vieussens, or superior medullary velum, is a thin plate of white
matter which fills in the angular interval between the superior peduncles of the
cerebellum. It is continuous behind with the white matter of the superior vermiform
process of the cerebellum. The lingula rests on the posterior part of its upper surface.
The fibres of the fourth nerve decussate within its substance at its upper part.
The inferior medullary vela are thin crescentic translucent bands of white
FIG. 427. RIGHT HALF OF THE ENCEPHALIC PEDUNCLE AS SEEN FROM THE INSIDE
OF A MEDIAN SECTION. (Allen Thomson, after Reichert.)

MIDDLE COMMISSURE-
OPTIC THALAMUS-
PINEAL BODY
CORPORA QUADRIGEMINA
DECLIVE
CRUS CEREBRI
ARBOR VITE
FOLIUM
CACUMINIS
TUBER
VALVULE
3
UVULA
PYRAMID
4
6
5
STRIA PINEALIS
THIRD VENTRICLE
ANT. PILLAR OF FORNIX
ANTERIOR COMMISSURE
LAMINA CINEREA
1
II
TUBER CINEREUM
RECESSUS INFUNDIBULI
PITUITARY BODY
-AQUEDUCT OF SYLVIUS
PONS
FOURTH VENTRICLE
-INFERIOR MEDULLARY VELUM
VI
-MEDULLA
1, culmen; 2, posterior crescentic lobe; 3, posterior inferior lobe; 4, slender lobe;
5, biventral lobe; 6, amygdala.
matter which extend from the nodule to the flocculus on each side; hence they
have been called commissuræ ad flocculos. Each velum presents a concave edge,
which is apparently free, but which is in reality continued into the epithelium, which
covers the choroid plexuses. It is attached to the cerebellum by its convex edge.
The choroid plexuses of the fourth ventricle are convoluted vascular folds of
the pia mater, which project into the cavity of the fourth ventricle, but are excluded
from the ventricular cavity by a layer of epithelium. They run at first forwards
close together on each side of the middle line, and then turn outwards along the
edges of the inferior medullary vela to reach the lateral recesses of the ventricle,
where they become continuous with the general pia mater.
The tela choroidea inferior is a layer of pia mater which closes in the lower
and back part of the fourth ventricle. It extends from the choroid plexuses to the
ligula and obex, where it is continued into the pia mater which covers the posterior
758
THE NERVOUS SYSTEM

surface of the lower part of the medulla. As already mentioned in the descrip-
tion of the meninges, it presents three openings or deficiencies: one (foramen of
Majendie) in the middle line immediately above the obex, and two (foramina of
Key and Retzius) at the lateral recesses.
The obex is a thin, somewhat triangular plate of white matter, occupying the
angular interval between the two diverging clave. It is not infrequently absent.
The ligula are thin narrow strips of white matter, which project from the
inner margins of the clave. They run at first upwards and forwards, and then
turn outwards around the restiform bodies. They may sometimes be traced as far
as the flocculi, when they become continuous with the inferior medullary vela.
Their inner, apparently free, edges are continuous with the epithelial roof of the
fourth ventricle.
The floor of the fourth ventricle is a depressed area, which is rhomboidal in
outline, the longer diameter of the rhomboid being directed upwards and forwards
and marked by a very distinct fissure, the sulcus longitudinalis medianus, which is
continuous below with the central canal of the spinal cord. The ventricular floor is
bounded laterally by the clave and corpora restiformia below, and by the superior
peduncles of the cerebellum above. Under cover of the obex, where the fourth
ventricle is about to join the central canal of the cord, a small ampulla is formed,
termed the ventricle of Arantius. The widest part of the floor corresponds to the
lateral recesses of the ventricle. Close behind the lateral recesses, the floor is crossed
by some white lines, the striæ medullares or striæ acusticæ, which emerge from
the sulcus longitudinalis medianus, and pass outwards to the auditory nerve. The
striæ divide the floor into two approximately equal parts, a posterior and an anterior.
The posterior moiety of the floor is indented by an angular groove, the
fovea inferior or posterior, which marks off a depressed triangular area of a grey
colour, the ala cinerea. The latter corresponds in position to the subjacent nuclei
of the vagus and glosso-pharyngeal nerves, and is therefore also termed the
trigonum vagi. The apex of the posterior fovea is directed forwards. It nearly
touches the striæ acustica, and thus two other triangular spaces, both of a
whitish colour, are marked off in the posterior moiety of the floor. The internal
of these spaces is called the trigonum hypoglossi, since it corresponds in position
to the nucleus of the hypoglossal nerve. It is bounded by the posterior fovea, the
striæ acusticæ, and the sulcus longitudinalis medianus. The outer triangle is
bounded by the posterior fovea, by the striæ acustica, and by the clavæ. It forms
the posterior part of a prominence or swelling which extends into the pontine
portion of the floor. This prominence is called the tuberculum acusticum. It
is well marked in the brain of the infant.
The anterior moiety of the floor is completely covered by a thin layer of white
substance. It presents, on each side of the sulcus longitudinalis medianus, a semi-
cylindrical elevation about five millimetres in length, which is called the eminentia
teres. It is caused by an underlying bundle of fibres, the fasciculus teres, which is
now known to be a part of the intrapontine course of the fibres of the facial nerve,
though possibly it may contain fibres from other sources. External to the eminentia
teres is a depressed area, the fovea superior, which is occasionally crossed by a
whitish band of fibres, the conductor sonorus. The conductor sonorus meets the stria
medullaris of its own side, at the sulcus longitudinalis medianus, at an acute angle.
Immediately in front of the fovea superior is a bluish spot, the locus cæruleus,
which is caused by the substantia ferruginea showing through the white covering
of the floor. The substantia ferruginea is an aggregation of darkly-pigmented cells,
which is very conspicuous in transverse sections through the upper part of the floor
of the fourth ventricle and through the lower part of the aqueduct of Sylvius.
The PONS VAROLII is that portion of the epencephalon which lies in front of the
proximal part of the fourth ventricle. As seen from the base of the brain, it forms

PONS VAROLII
759
a considerable prominence, which narrows on each side as it passes into the
middle cerebral peduncles. At its lower border the pyramidal bodies are seen dis-
appearing into its substance, while at its upper border the crura cerebri are seen
emerging. It rests on the body of the sphenoid bone, reaching upwards as far as
the margin of the dorsum sellæ. It presents a ventral and a dorsal surface, and a
superior and an inferior border. Lateral surfaces have also been described, but
these are determined artificially by dividing the pons proper from the middle
cerebellar peduncles. The boundary between the pons and the middle cerebellar
FIG. 428.-METENCEPHALON, MESENCEPHALON, AND THALAMENCEPHALON, FROM
THE DORSAL SURFACE. (After Obersteiner.)

ANTERIOR CORNU-
OF LATERAL
VENTRICLE
FIFTH
VENTRICLE
SEPTUM LUCIDUM-
ANTERIOR
PILLARS OF
FORNIX
TENIA
SEMICIRCULARIS
ANTERIOR
COMMISSURE
THIRD-
VENTRICLE
MIDDLE
COMMISSURE
SULCUS
CHOROIDEUS
NATES
CORPUS
GENICULATUM
INTERNUM
LATERAL
GROOVE OF
MESENCEPHALON
PONS-
CONDUCTOR
SONORUS-
SULCUS LONGITUDINALIS
MEDIANUS
TRIGONUM HYPOGLOSSI
CORPUS RESTIFORME
AV
Vil
CLAVA-
POSTERIOR FISSURE-
SULCUS PARAMEDIANUS.
DORSALIS
SULCUS LATERALIS
DORSALIS
CORPUS CALLOSUM
CAUDATE NUCLEUS
FORAMEN OF MONRO
OPTIC THALAMUS
STRIA PINEALIS
PEDUNCULUS
CONARII
PINEAL BODY
SULCUS CORP. QUAD.
LONGITUDINALIS
TESTIS
FRENULUM VELI
LINGULA
EMINENTIA TERES
TUBERCULUM
ACUSTICUM
ALA CINEREA
TUBERCULUM CUNEATUM
FUNICULUS GRACILIS
FUNICULUS CUNEATUS
LATERAL COLUMN
peduncles on each side is arbitrarily mapped out by a line drawn from the exit of
the trigeminal nerve to the superficial origin of the facial. (Henle.)
The dorsal surface has been described in connection with the floor of the fourth
ventricle.
The ventral surface is broad and prominent, strongly convex from side to side,
and slightly convex from before backwards. It presents a transverse striation,
corresponding to the bundles of commissural fibres passing from hemisphere
to hemisphere of the cerebellum. Mesially, it is marked by a sagittal groove or
furrow, which usually lodges the basilar artery, but is in no way caused by the
760
THE NERVOUS SYSTEM
contact with the vessel. On each side of the groove a prominence is formed, where
the sagittally-directed fibres of the pyramidal bodies pass brainwards, under cover
of the transverse fibres of the pons.
The superior border is convex forwards. Its fibres pass directly into the upper
border of the middle peduncle of the cerebellum.
The inferior border is marked off by a distinct transverse groove from the
medulla. It is formed in its inner part by the lowest fibres of the pons, but these
are crossed near the junction of pons and middle peduncle by the oblique fasci-
culus. The oblique fasciculus is formed by the middle transverse fibres of the
pons, which pass downwards and backwards, internal to the exit of the trigeminal
nerve, on each side, and cross the inferior fibres on their superficial aspect.
Coronal sections through the pons (fig. 429) show that it comprises two very
distinct regions-an anterior or ventral region and a dorsal region, which is called
tegmental, as most of its constituents are continued into the tegmentum of the
mesencephalon. The ventral region consists of transverse and longitudinal fibres,
interspersed with small aggregations of grey matter. The transverse fibres are of
three kinds: (a) Commissural, from hemisphere to hemisphere-these preponderate
on the anterior surface; (b) decussating fibres, which, after emerging from the
cerebellum by the middle peduncles, cross over to the opposite side and pass
upwards to the cerebrum; (c) fibres which take origin from the grey matter of
the pons, and cross over to the cerebellar hemisphere of the opposite side. These
are probably cerebral fibres which have suffered an interruption in the nerve
cells of the pons. The longitudinal fibres are the upward continuation of the
pyramids. They pass upwards in flattened bundles, separated from one another
by some of the transverse fibres of the pons.
In the upper or tegmental region the chief things to be observed are: the
tract of the fillet (which lies next to the ventral region), the formatio reticularis,
the posterior longitudinal bundle, the substantia ferruginea, and the funiculus
teres. The superior olivary nucleus, the nuclei of the sixth and seventh cranial
nerves, the motor nucleus of the trigeminal, with parts of the ascending and
descending roots of the last-named nerve and portions of the nucleus of the
auditory nerve, are embedded in this region of the pons.
Some of the structures mentioned in the preceding paragraph are visible to the unaided
eye in ordinary dissecting-room specimens. The nuclei of the cranial nerves will not be
further described here, as a full account of them will be given in the section on the cranial
nerves.
THE METENCEPHALON
The MEDULLA OBLONGATA, or bulb, is the portion of the cerebro-spinal axis
which extends from the inferior border of the pons to the decussation of the pyramids.
It presents an anterior, a posterior, and two lateral surfaces. The anterior surface
rests upon the basilar groove of the occipital bone, and extends downwards as far
as the point where the odontoid process is crossed by the transverse ligament of
the atlas (Testut). The bulb has the form of a truncated cone, the base of which
is continued into the pons above, while the truncated apex is prolonged into the
spinal cord below. The posterior surface is received into the vallecula, between
the cerebellar hemispheres, and forms, by its upper part, as already described,
the lower or posterior part of the floor of the fourth ventricle. The ninth to the
twelfth nerves (with the exception of the spinal part of the spinal accessory) take
their superficial origin from its sides. The sixth, seventh, and eighth nerves
appear in the transverse groove between the medulla and the pons in numerical
order from within outwards.
The ventricular part of the medulla has been already described; but on the


METENCEPHALON
761
extraventricular portion certain fissures, and the elevated portions which these
fissures map out, require notice.
Fissures.-Commencing in front, we find the anterior fissure (fissura longitu-
dinalis anterior) occupying the middle line. It is shallow below, where it is almost
separated from the anterior longitudinal fissure of the cord by the decussation of
the pyramids; deeper above, where it separates the pyramids of opposite sides.
Above, it ends in a blind recess, under the margin of the pons, the foramen cæcum
posterius, or foramen cæcum of Vicq d'Azyr. External to the anterior fissure, we
find the sulcus lateralis ventralis; the latter intervenes between the pyramid and
the olive above, and extends downwards immediately in front of the olive and the
lateral column. It is joined below the olive by the postolivary sulcus. From its
upper part, a fissure (sulcus parapyramidalis) passes downwards and inwards to
join the anterior fissure.
On the posterior surface of the medulla we find the posterior fissure (fissura
longitudinalis posterior) occupying the middle line. It is continuous below with
the posterior fissure of the spinal cord, and ends above at the fourth ventricle.
External to this we find the sulcus paramedianus dorsalis, and more externally the
sulcus lateralis dorsalis. The former of these two fissures ends above at the apex
of the clava, the latter extends for some distance further upwards. To recapitulate,
the fissures of the medulla, taken in order from before backwards, are as follow:
fissura longitudinalis anterior, sulcus parapyramidalis, sulcus lateralis ventralis,
sulcus postolivaris, sulcus lateralis dorsalis, sulcus paramedianus dorsalis, fissura
longitudinalis posterior. As will be seen from the previous description, however,
this summary applies only to the upper or proximal part of the medulla; in the
distal part the fissures become reduced in number owing to some of them becoming
confluent with others. Certain of the above-mentioned fissures divide the medulla
into columns or areas corresponding, for the most part, to the columns of the cord.
Thus we have an anterior area between the anterior fissure and the sulcus lateralis
ventralis, a lateral area between the last-named fissure and the sulcus lateralis
dorsalis, and a posterior area between the sulcus lateralis dorsalis and the posterior
fissure.
The anterior area of the medulla is occupied, for the greater part of its extent,
by the pyramidal bodies. These are a pair of prominences somewhat pyriform
in outline, which lie on each side of the anterior median fissure. Their larger
ends are directed upwards and abut against the pons where they become slightly
constricted. Laterally, they are marked off by the sulci parapyramidales. Their
apices are directed downwards and correspond to the decussation of the pyramids.
The greater number of the fibres pass across at this point and make their way into
the lateral column of the opposite side of the cord (lateral pyramidal tract); a small
bundle, however, of the outermost fibres of each pyramid runs downwards in the
anterior column of the cord of the same side (anterior pyramidal tract).
The remainder of the anterior column is occupied by the funiculus anterior.
This is a triangular area of white substance which intervenes between the sulcus
parapyramidalis and the sulcus lateralis ventralis. Its base is directed downwards,
and is continuous with the anterior ground bundle of the anterior column of the
cord. Its apex, directed upwards, is wedged in between the olivary and pyramidal
bodies. The progressive diminution of the tract when traced upwards is owing to
its fibres receding from the surface, being overlapped by the pyramidal body.
The lateral area of the medulla is narrow below, being formed by the continua-
tion of a portion only of the lateral column of the cord. Higher up it expands and
presents: (a) The olivary body and (b) the tubercle of Rolando. The lateral column
is a band which passes upwards between the sulcus lateralis ventralis and the sulcus
lateralis dorsalis. Above, it passes behind the lower part of the olivary body, and
here a greyish prominence, the grey tubercle of Rolando, comes to the surface.


762
THE NERVOUS SYSTEM
Beyond this the lateral column can be followed as a narrow band behind the olive as
far as the transverse groove at the lower border of the pons. The olivary body is an
ovoidal prominence from twelve to sixteen millimetres long, which extends upwards
as far as the transverse groove at the lower border of the pons. It is separated
from the pyramidal body by the sulcus lateralis ventralis, and marked off externally
by the sulcus postolivaris. Its lower end is crossed by the external arciform fibres.
The external arciform fibres emerge from the anterior longitudinal fissure and
from the sulcus lateralis ventralis, and arch round the pyramidal and olivary bodies
to join the restiform body of the same side.
The posterior area of the medulla is occupied in its lower part by two slender
fasciculi, each of which expands above into a tubercle. The inner of the two
is called the funiculus gracilis, the outer the funiculus cuneatus. The funiculus
gracilis is separated from its fellow of the opposite side by the posterior fissure.
As it approaches the lower extremity of the fourth ventricle, it swells out into a
FIG. 429.-TRANSVERSE SECTION THROUGH THE UPPER PART OF THE PONS. (Schwalbe.)
VALVE OF VIEUSSENS
LINGULA

DESCENDING ROOT OF
TRIGEMINAL
FOURTH
VENTRICLE
RAPHE
00008
00
SUPERIOR PEDUNCLE
OF CEREBELLUM
POSTERIOR
LONGITUDINAL
BUNDLE
FILLET
FORMATIO
RETICULARIS
TRACT OF
FILLET
TRIGEMINAL
NERVE
BUNDLES OF
THE PYRAMIDS
TRANSVERSE FIBRES OF PONS
prominence called the clava. The latter diverges from its fellow of the opposite
side, bounding the fourth ventricle. When traced upwards it gradually tapers off
into a fine point. To the inner margins of the diverging portions of the clave we
find the obex and ligula attached, as already described (page 758). The funiculus
cuneatus is placed between the funiculus last described and the lateral area of the
medulla. At the level of the clava it swells out into a prominence, the cuneate
tubercle. Above this point it disappears from the surface.
The upper part of the posterior area is occupied by the restiform body. The
latter appears at first sight as if it were the continuation upwards of the funiculus
cuneatus and of the lateral tract, and this was formerly described to be the
It is now known, however, that it is formed by the direct cerebellar tract
(page 781), the external arciform fibres, and the deep or internal arciform fibres
(page 783). These constituents unite and form a rounded cord which proceeds
upwards and then backwards to the cerebellum, forming the inferior peduncle of
that body. In its lower part it is embraced by the roots of the auditory nerve. It
then passes through a gap or interval between the superior and middle cerebellar

METENCEPHALON
763
peduncles, and ends in the superior vermiform process of the cerebellum in the
nucleus fastigii.
As already mentioned, the superficial origins of the cranial nerves appear on
the surface of the medulla. The sixth, seventh, and eighth nerves come to the
surface in the transverse groove between the medulla and pons (fig. 441). The
twelfth nerve appears by a row of filaments in the groove between the olivary and
pyramidal bodies, and in a line with these filaments, opposite the decussation of the
pyramids, the upper part of the anterior root of the first cervical nerve comes to
the surface. Between the olivary and restiform bodies, the ninth, tenth, and the
upper part of the eleventh nerves make their appearance, and behind the latter the
upper filaments of the posterior root of the first cervical nerve reach the surface.
Dissection. If the student has followed out the dissection previously recommended, the
brain will now be reduced to the medulla, the pons, the mesencephalon, and small portions

FIG. 430.-TRANSVERSE SECTION OF THE PONS NEAR THE CENTRE OF THE FOURTH
VENTRICLE. (Schwalbe.)
SEVENTH-
NERVE
RAPHE
CORPUS
TRAPEZOIDES
SEVENTH NERVE
NUCLEUS OF SIXTH

NUCLEUS OF
EIGHTH
FORMATIO
RETICULARIS
NUCLEUS
OF
SEVENTH
ASCENDING
ROOT OF
FIFTH
AUDITORY
NERVE
SUPERIOR
OLIVE
SIXTH NERVE
CONTINUATION
OF PYRAMIDS
of the hemispheres (chiefly thalamencephalon). He should now tear off the transverse
fibres of the pons on one side of the middle line, so as to bring into view the flattened
bundles which form the continuation of the pyramidal body through the pons. By tearing
these pyramidal fibres in a sagittal direction, the dissector will be able to follow them
through the crusta into the inner capsule. Lastly the dissector should make a series of
transverse sections through the remaining portion of brain-substance. An inspection of
figs. 423, 424, 429, 430, and 431 will materially aid him in comprehending the somewhat
faint indications which he will observe in his sections.
The following are the principal points which can be made out by the unaided eye in
an ordinary brain, hardened in spirit, and treated in the above-mentioned manner. (In a
brain hardened in Müller's fluid many additional details can be made out.) In the upper-
most sections the tegmental or red nucleus is readily recognised by its rounded outline; it
lies below the optic thalamus, and extends backwards for a considerable distance (fig. 423).
If the section pass through the external geniculate body, curved bands of white matter
intersecting the grey matter can be seen. Sections through the upper part of the mesen-
cephalon show the red nucleus in the tegmentum, the substantia nigra, the crusta, and the
aqueduct of Sylvius. Lower down, the decussation of the superior peduncles of the cere-
bellum forms a conspicuous white centre in the tegmentum; the grey matter surrounding
the aqueduct is distinct in colour from the rest of the section, and on the ventral side of
this grey matter the posterior longitudinal bundle can be faintly made out. Sections
through the inferior corpora quadrigemina show the posterior longitudinal bundle more
distinctly; the superior peduncles of the cerebellum lie on the ventral side of the bundle,
touching one another at the raphe, but commencing to rise up around the sides of the
aqueduct; ventral to these the tract of the fillet may be seen as a white band; and ventrally
764
THE NERVOUS SYSTEM
to the fillet the longitudinal fibres of the pons are well seen intersecting the transverse
fibres. Sections through the valve of Vieussens (fig. 429) show the superior peduncles of
the cerebellum in the form of distinct white crescents placed laterally to the floor of the
fourth ventricle. The posterior longitudinal bundle is now very distinct. It appears
pear-shaped in cross-section with the narrow end pointing outwards and abutting against
the substantia ferruginea; the latter stands out as a conspicuous dark spot. The tract of
the fillet is easily recognised as a white flattened oval bundle. The area mapped out
between the posterior longitudinal bundle, the superior peduncles of the cerebellum, and
the tract of the fillet, is occupied by the formatio reticularis. In sections distal to this, the
posterior longitudinal bundle and the tract of the fillet rapidly lose their distinctness, and
in the medulla little can be made out as a rule except the olivary nucleus. The latter
appears as a thin wavy grey line occupying the interior of the olivary body.
FIG. 431.-TRANSVERSE SECTION OF THE MEDULLA A LITTLE ABOVE THE LOWER
EXTREMITY OF THE FOURTH VENTRICLE. (After Krause.)
FUNICULUS SOLITARIUS
NUCLEUS OF AUDITORY

NUCLEUS
FUNICULI
GRACILIS ET
CUNEATI
SUBSTANTIA-
GELATINOSA
ASCENDING
ROOT OF
FIFTH
VAGUS-
NUCLEUS
LATERALIS
VAGUS
EXTERNAL
ACCESSORY
OLIVE
ARCIFORM
FIBRES
OLIVARY
NUCLEUS
HYPOGLOSSAL-
PYRAMIDAL BODY-
NUCLEUS OF VAGUS
SULCUS LONGI-
TUDINALIS
MEDIUS
NUCLEUS OF
HYPOGLOSSAL
-INTERNAL
ACCESSORY
OLIVE
-RAPHE
FISSURA
LONGITUDI-
NALIS
ANTERIOR
Internal structure of the medulla.-Transverse sections of the medulla show
that it is composed of symmetrical halves separated by a central raphe. The raphe
is entirely formed by decussating fibres. Each lateral half is composed of both
grey and white matter. The white matter will be dealt with in common with the
tracts of the spinal cord and with the cranial nerves.
The arrangement of the grey matter in the medulla is, for the most part, not
visible to the unaided eye, and therefore will be dealt with very briefly here. It is
usually classified into two categories: (a) Representatives of the grey crescents of
the spinal cord; and (b) nuclei or aggregations of grey matter not represented in the
spinal cord. As will be seen on consulting the section on the SPINAL CORD, the grey
matter of the latter consists of a pair of bilaterally symmetrical grey crescents
METENCEPHALON
765
which are united in the middle line by a grey commissure. In the centre of this
commissure is the central canal of the cord. This central canal extends upwards
into the lower or distal part of the medulla, but, in the upper part of the last-
named structure, the posterior columns diverge from one another so that the
central canal opens out and expands into the floor of the fourth ventricle. There-
fore the ependyma which surrounds the central canal, together with the grey
masses at the bases of both anterior and posterior horns, is spread out on the floor
of the fourth ventricle. From the nerve-cells in this grey matter some of the
cranial nerves, which take their origin in the medulla, arise. The grey matter of
the base of the anterior horn suffers but little displacement, and lies in a column
on each side of the sulcus longitudinalis medianus, and from this a motor nerve (the
twelfth) arises. The sixth nerve arises in series with the twelfth in the tegmental
region of the pons, and the nuclei of the fourth and third nerves continue this motor
column of cells brainwards. The grey matter of the base of the posterior horn is dis-
placed laterally, so that it underlies the surface markings which have been described
above as ala cinerea and tuberculum acusticum, and from this grey matter the
sensory parts of the tenth and ninth nerves and part of the eighth nerve arise.
FIG. 432.-TRANSVERSE SECTION OF THE MEDULLA IN THE REGION OF THE
DECUSSATIO LEMNISCI. (Schwalbe.)

FUNICULUS CUNEATUS
NUCLEUS OF THE CLAVA
EXTERNAL CUNEATE
NUCLEUS
CUNEATE NUCLEUS
ASCENDING ROOT OF
TRIGEMINAL
SUBSTANTIA GELATINOSA-
FORMATIO RETICULARIS-
NUCLEUS LATERALIS
OLIVARY NUCLEUS-
SUPERFICIAL ARCIFORM
FIBRES
ARCIFORM NUCLEUS-
FUNICULUS GRACILIS
POSTERIOR FISSURE
NUCLEUS OF SPINAL
ACCESSORY
CENTRAL CANAL
-NUCLEUS OF HYPOGLOSSAL
-DECUSSATIO LEMNISCI
-ACCESSORY OLIVARY
NUCLEUS
-ANTERIOR FISSURE
SUPERFICIAL ARCIFORM
FIBRES
The heads of both of the horns of the grey crescents are also represented in the
medulla. At the decussation of the pyramids (fig. 438) large bundles of fibres pass
from the lateral columns of the cord to cross over to the opposite side and appear
in the anterior column of the medulla, forming the greater part of the pyramids.
These bundles of fibres cut through the necks of the anterior horns so as to com-
pletely amputate the heads of the horns. A little higher up each head is thrust
into a more lateral position by the increased size of the pyramids, and forms the
nucleus lateralis and the nucleus ambiguus (fig. 432). The motor nuclei of the por-
tion of the eleventh which arises in the medulla, and of the tenth and ninth nerves,
are regarded as derivatives from the head of the anterior horn, and the series is
continued upwards by the nucleus of the seventh (at the junction of the pons and
medulla), and in the pons by the motor nucleus of the trigeminal. A little above
the decussation of the pyramids, bundles of fibres, chiefly from the funiculi gracilis
and cuneatus, pass forwards and cut through the neck of the posterior horn, and
then decussate, forming the sensory or upper pyramidal decussation (decussatio
lemnisci). The separated head of the posterior horn (substantia gelatinosa Rolandi)
is continued upwards as far as the accessory sensory nucleus of the fifth nerve.
This substantia gelatinosa is one of the sensory nuclei of the fifth nerve, and is


766
THE NERVOUS SYSTEM
covered externally by a band of white fibres, concave inwards, the ascending root
of the trigeminal nerve (fig. 432). At one point the substantia gelatinosa approaches
very near the surface, and forms the grey tubercle of Rolando.
Of the nuclei which are apparently without representatives in the
grey matter
of the spinal cord, the most important is the olivary nucleus; this is a crumpled bag
of grey matter enclosing white matter and occupying the interior of the olivary
body. It can easily be seen with the unaided eye in cross-sections of the medulla.
It presents a marked resemblance, in miniature, to the corpus dentatum of the
cerebellum, and is often called the corpus dentatum of the olivary body. It presents
an opening or hilum which opens downwards and inwards. The nucleus of the
clava and the nucleus cuneatus are not directly represented in the cord, but
their connection with the posterior horns can be seen in sections through the lower
part of the medulla; they have probably the same anatomical value as a column of
nerve-cells (Clarke's column) in the dorsal region of the spinal cord (Testut).
Other nuclei of smaller size are found in the medulla; the nucleus arciformis and
the accessory olives will serve as examples of these (fig. 431). None of these
smaller nuclei are visible to the unaided eye.
Specific Gravity and Weight of the Brain
The average specific gravity of the brain is about 1036. The white matter is somewhat
more heavy (sp. gr. 1040) than the grey matter (sp. gr. 1034).
The adult male brain weighs on an average 49.5 ounces; the female brain is somewhat
lighter, and weighs from 5 to 5.5 ounces less than the male.
The cerebrum forms about 87.5 per cent. of the entire brain; the cerebellum about 10.5
per cent.; and the pons and medulla about 2 per cent.
Weight of the Spinal Cord
In the adult, the spinal cord, when all extraneous structures have been removed, weighs
from 1 to 1.5 ounce.

CRANIO-CEREBRAL TOPOGRAPHY
The great advances which have been made during late years in cerebral surgery
render it imperative that the student should become acquainted with, at least, the
more important facts concerning the relations which exist between the encephalon
and the cranium with its covering of soft parts.
The first observers considered that the lobes of the brain corresponded to the
bones of the same name; this is now known not to be the case. It has also been
demonstrated that the sutures of the skull are much more variable in their relations
to the fissures of the brain than was originally supposed. The principal fissures
are found to be fairly constant in their position, while the sutures vary consider-
ably in their relation to these fissures.
Guide-points. In attempting to map out the outline of the brain and its
fissures and convolutions on the surface of the head, advantage is taken of certain
prominent points and ridges, which can, under ordinary circumstances, be felt
through the skin in the living head. Some of these are very definite, and therefore
valuable; while others have been suggested by various authors which are so obscure
and variable as to be practically useless. The following is a list of the principal
guide-points which have been employed: the glabella, the naso-frontal groove,
the orbital arch, the external angular process, the zygoma, the external auditory
meatus, the mastoid process, the superior curved line of the occipital bone, the
external occipital protuberance, the parietal eminence, and the sutures of the skull.
The glabella is an eminence which is situated between the superciliary ridges.
CRANIO-CEREBRAL TOPOGRAPHY
767
It has been used as a guide-point by the majority of authors, but it may well be
replaced, as Poirier has proposed, by the naso-frontal groove. The glabella is
variable, being elevated in some skulls, and rounded off to such a degree in others
as to be hardly perceptible. Moreover, it is rather an area than a definite point
from which measurements could be taken; while the naso-frontal groove is easily
localised, very constant in its relations to the anterior poles of the cerebral hemi-
spheres, and is a very convenient point from which to take measurements.
The naso-frontal groove (the centre of which is termed the nasion) can be easily
recognised in the living head as a definite depression. It corresponds to the suture
between the nasal and frontal bones.
The orbital arch is easily recognised. Its inner extremity, the internal angular
process, is deeply placed. Its outer extremity, the external angular process, is very
prominent.
The external angular process can be easily felt, and its anterior and posterior
borders made out. The posterior border is a very convenient point from which to
take measurements.
The zygoma, being subcutaneous for its entire extent, is easily recognised. Its
upper border corresponds, broadly speaking, to the infero-external border of the
temporal lobe. This border, however, frequently dips below the upper border of the
zygoma, as may be seen in the series of casts prepared by Professor Cunningham.
The zygoma, from the fact of its being practically horizontal, may be of further
use in determining the horizontal plane in the recumbent position of the body.
The external auditory meatus possesses the advantage of being visible as well as
tangible, and (according to Poirier) of bearing a very constant relation to the contents
of the cranial cavity. In determining the position of the fissure of Rolando by
Reid's method, the depression in front of the meatus is selected as a landmark.
The mastoid process is easily felt, except in young children. The posterior
border of the root of this process is the point from which, in Reid's method, a
vertical line is drawn to meet the middle line.
The superior nuchal line corresponds to the upper limit of the muscles of the
neck, and can be felt, in many persons, pursuing a curved course from the posterior
border of the mastoid process to the external occipital protuberance.
The external occipital protuberance, or inion, is one of the most useful guide-
points. It corresponds to the posterior end of the great longitudinal fissure, and
can usually be easily made out as a distinct eminence. In some cases it is slightly
developed and, in such cases, its position may be determined by following the
superior nuchal line towards the mesial line of the head, or by making tense the
ligamentum nuchæ, which is attached to the protuberance.
The parietal eminence is very prominent in the young child, but in the adult it
becomes rounded off, and is too obscurely marked to be of much use as a landmark.
The sutures are of very little practical use, as they cannot easily be dis-
tinguished until the soft parts have been reflected, and, as above mentioned, the
sutures vary considerably in their relations to the fissures of the brain. The
lambda can, however, be generally made out as a depression immediately in front
of the highest point of the occipital bone.


Various methods have been employed in determining the relations of the cerebral con-
volutions and fissures to the superficial landmarks of the head. Pegs have been driven
through the skull, along the sutures, into the brain, and the relations of these sutures to
the brain thus ascertained. Much information has also been obtained from the study of
sections of frozen heads. Composite photographs of dissections have also been prepared,
showing the convolutions, and even the ventricular cavities, of the brain in relation to the
surface of the head, the head appearing transparent (Fraser). Lastly, the brain, having
been hardened in situ, has been exposed by removing portions of the skull-wall and casts
have been made of the preparations (Cunningham). Figs. 433 and 434 are drawn from
two of these casts.

768
THE NERVOUS SYSTEM
Relation of the margin of the hemisphere to the cranial wall. The mesial
border of the hemisphere may be mapped out by taking on the surface of the scalp
a point about half an inch above the superior nuchal line of the occipital bone,
three-quarters of an inch on the right side (a quarter of an inch on the left)
from the centre of the external occipital protuberance, and drawing a straight
line forwards from this point to the naso-frontal groove. This line gradually
approaches the middle line as it is traced forwards in consequence of the narrowing
of the superior longitudinal sinus.
The orbital margin of the hemisphere commences opposite the floor of the naso-
frontal groove, and passes upwards and outwards above the orbital arch, gradually
FIG. 433.-DRAWING OF A CAST OF THE HEAD OF AN ADULT MALE.
(Prepared by Professor Cunningham to illustrate cranio-cerebral topography.)
FISSURE OF
ROLANDO
INTRA-
PARIETAL
FISSURE
POSITION OF
PARIETAL
EMINENCE
EXTERNAL
PARIETO-
OCCIPITAL
FISSURE
Lateral sinus
POSITION OF
FRONTAL EMINENCE
-FISSURE OF
SYLVIUS
PARALLEL
FISSURE
MIDDLE
TEMPORAL
FISSURE
rising until it reaches a point situated from eight to fifteen millimetres above the
external angular process; from this point it passes almost horizontally backwards
to the point (Sylvian point) where the fissure of Sylvius reaches the convex surface
of the hemisphere. The Sylvian point is placed from twenty-nine to thirty-two
millimetres behind the external angular process. From this point the upper
margin of the anterior part of the temporal lobe runs downwards and forwards
towards the apex of the temporal lobe as far as a point which is situated on an
average about fifteen millimetres behind the external angular process, and two
millimetres above the zygoma. From this point the infero-external border
commences, and passes backwards, with a slight inclination downwards, as far as
the temporo-mandibular articulation, and is here on a level with the upper border
CRANIO-CEREBRAL TOPOGRAPHY
769
of the zygoma. It runs then backwards and slightly upwards, passing four to ten
millimetres above the external auditory meatus, and follows the same direction as
far as a perpendicular line drawn upwards from the posterior border of the mastoid
process at its root; then, slightly changing its direction, it passes backwards, with
an inclination downwards, a little above the superior nuchal line to the external
occipital protuberance.
In the above description the method of Poirier has been partly followed. It should be
noted that the apex of the temporal lobe is directed inwards as well as downwards and
forwards, so that it is related to the base rather than to the lateral wall of the skull. In a
brain hardened in situ (fig. 410), the apex of the temporal lobe is seen to be sharply
pointed, while, about one-half to three-quarters of an inch above and behind the apex, an
elevation is seen crossing the three temporal convolutions. This elevation corresponds to
the margin of the part of the hemisphere which is in relation to the lateral wall of the skull,
and is apparently the blunt pole (pointe mousse) of the temporal lobe referred to by Poirier.
In tracing the mesial border of the hemisphere, a quarter of an inch on the left side and
three-quarters of an inch on the right side is allowed for the superior longitudinal sinus.
This allows an inch for the breadth of the sinus, which would be too large for the superior
longitudinal sinus alone; but we must also take into account the commencement of the
lateral sinuses, which begin to deviate at this point. The inion is a little below the occipital
pole of the cerebral hemispheres. The superior nuchal line generally corresponds, as
Birmingham has shown, to the lateral sinus at its posterior or inner part. [In six skulls I
drilled a series of holes horizontally through the superior nuchal line of the occipital bone
on each side. Most of the holes entered the groove for the lateral sinus or pierced the skull
below that groove. In three skulls, holes drilled through the nuchal line at a point half an
inch external to the inion on the left side passed above the sinus, and would therefore have
entered the cerebrum in the recent state. In every instance the nuchal line was situated
entirely below the cerebrum on the right side. From the average of the six skulls examined
it would appear that the inner third of the superior nuchal line corresponds to the lower
border of the lateral sinus or to the margin of the cerebellum; the middle third of the
nuchal line to the lateral sinus near its upper border; and the outer third of the nuchal line
to the cerebellum.-H. ST. J. B.]
Position of the principal fissures.-The methods in use in this country up
to the present time for determining the relations of the principal fissures to
the surface of the head are chiefly those of Hare and Reid. The former mainly
devoted himself to mapping out the most important fissure, namely, the fissure
of Rolando. He found that the upper end of this fissure was on an average
57 per cent. of the surface-distance from the glabella to the external occipital
protuberance, that its average length was 33 inches, and that it formed an angle of
67° with the mesial line of the head. This angle has recently been shown to
more nearly average 71.5° (Cunningham). Reid refers most of his markings to
perpendiculars erected on a line drawn from the lowest part of the infraorbital
margin backwards through the middle of the external auditory meatus. He calls
this line the base line.' The rules which follow in this article for determining
the positions of the various fissures are based mainly on the observations of Hare,
Poirier, and Cunningham.
Fissure of Rolando.-If the distance from the floor of the naso-frontal groove
to the external occipital protuberance be measured, and a point be taken two
centimetres behind the central point of this line, it will indicate the upper end of
the fissure of Rolando. From this point a line should be drawn downwards and
forwards for a distance of 8.6 centimetres (33 inches), forming an angle of 71.5°
with the mesial line. In cases where the external occipital protuberance cannot
be satisfactorily made out, the upper end of the fissure of Rolando may be found
by measuring a distance of eighteen centimetres in large heads (or seventeen
centimetres in small heads) from the naso-frontal groove. (Poirier.)
[In this method of determining the position of the fissure of Rolando, I have employed
Poirier's method for determining the upper extremity of the fissure, the Rolandic angle as
determined by Cunningham, and the length of the fissure as given by Hare. I recently
measured eight of Professor Cunningham's casts, both by the above method and by Hare's.


3 D

770
THE NERVOUS SYSTEM
The fissure coincided with the measurement, by both methods, in four cases. In three
out of the remaining four cases an inch trephine would have exposed the fissure in both
series of measurements, while in one case the fissure would have formed a tangent to the
trephine circle by the above method, and would have missed the fissure by about two
millimetres by Hare's method. I attribute this failure to the difficulty of determining
the glabella with precision.-H. ST. J. B.]
Naso-lambdoidal line. Poirier has introduced a line which he terms the naso-
lambdoidal line. This line is drawn from the naso-frontal groove to a point
one centimetre above the lambda. It touches the lower pointed extremity of the
pars triangularis of the inferior frontal convolution, runs for a distance of from
four to six centimetres along the posterior limb of the fissure of Sylvius, grazes
the inferior part of the supramarginal convolution, passes through the base of
the angular gyrus, and abuts on the external parieto-occipital fissure. About
the middle of its course, the naso-lambdoidal line passes through a point situated
six millimetres above the external auditory meatus. In cases where the lambda
FIG. 434.-DRAWING OF A CAST OF THE HEAD OF A NEWLY-BORN MALE INFANT.
(Prepared by Professor Cunningham to illustrate cranio-cerebral topography.)
INTRA-
PARIETAL
FISSURE
EXTERNAL
PARIETO-
OCCIPITAL
FISSURE
-FISSURE OF
ROLANDO
POSITION OF
PARIETAL EMI-
NENCE
POSITION OF
-FRONTAL EMINENCE
FISSURE OF
SYLVIUS
PARALLEL
FISSURE
cannot be defined by touch, it can be found at a distance of seven centimetres
above the external occipital protuberance. (Poirier.)
Fissure of Sylvius.-The following directions are given by Reid for finding
this sulcus:- Draw a line from a point one inch and a quarter behind the external
angular process of the frontal bone to a point three-quarters of an inch below the
most prominent part of the parietal eminence. Measuring from before backwards,
the first three-quarters of an inch of the line will represent the main fissure, and
the rest of the line will indicate the horizontal limb. The ascending limb will
start from the posterior end of the line indicating the main fissure-that is, two
inches behind, and slightly above, the external angular process-and run vertically
upwards for about an inch.' In making these measurements, the chief difficulty
is the vague contour of the parietal eminence; it will therefore be advisable
to check the result obtained by drawing the naso-lambdoidal line.

THE SPINAL CORD
771
External parieto-occipital fissure. This fissure is situated, according to Hare,
on an average, five-eighths of an inch in front of the lambda, or one inch and
seven-eighths behind the upper end of the fissure of Rolando. It may also be
found at the posterior end of the naso-lambdoidal line.
[In Professor Cunningham's series of casts, the relation of the lambda to the external
parieto-occipital fissure is seen to vary considerably. The fissure is generally in front of
the lambda, but is in one case under cover of that landmark. I recently measured the
distance of the parieto-occipital fissure from the upper end of the fissure of Rolando in
five of these casts, and found it slightly in excess of the measurement given above-viz.
2.3 inches-the limit of variability being half an inch.-H. ST. J. B.]
Angular gyrus.-This convolution is situated on the naso-lambdoidal line,
seven centimetres from the lambda. (Poirier.)
Supramarginal convolution. This is placed immediately above the naso-
lambdoidal line at a distance of ten centimetres from the lambda. (Poirier.)
THE SPINAL CORD
The spinal cord is the elongated portion of the cerebro-spinal axis which is
contained within the spinal canal. It extends from the level of the transverse
FIG. 435.-TRANSVERSE SECTION OF THE SPINAL CORD AND ITS MEMBRANES.

(After Key and Retzius.)
Dura mater
-SUBARACHNOID SPACE
-ANTERIOR NERVE-ROOTS
(in section)
Ligamentum denticulatum
SUBARACHNOID
TRABECULA WITH
BUNDLES OF
POSTERIOR NERVE-
ROOTS
Septum posticum
ligament of the atlas to the body of the second lumbar vertebra. Occasionally it
only extends as far as the body of the first lumbar vertebra. It is invested, in
common with the brain, by three membranes: dura mater, arachnoid, and pia mater.
The portions of these membranes which are contained within the cranial cavity, and
are therefore in relation to the brain, have been already described (page 710). There
are, however, certain differences between the cranial and the spinal meninges; there-
fore, a short separate description of the latter will be necessary.
Dissection. The subject being placed on its face, the neural canal may be laid in
open
the usual manner by cutting through the pedicles of the vertebræ and removing the neural
arches of the sacrum.
The cord and its membranes should be first examined in situ.
About three inches of the theca should be ripped up at the junction of the dorsal and
lumbar regions for this purpose. The entire cord with the membranes should then be
removed by dividing both cord and membranes at the level of the articulation between
the atlas and axis and cutting through the nerves as they enter the intervertebral foramina.
Two or three of the lower lumbar or upper sacral nerves should be cut sufficiently long
to preserve the ganglia on the posterior roots. The cord should now be pinned out with
3D2

772
THE NERVOUS SYSTEM
its posterior surface uppermost in a cork-lined tray and dissected under water. On laying
open the dura mater by a mesial longitudinal incision, the arachnoid will come into view
and will be rendered more evident by blowing air between it and the pia mater with a
blowpipe. On slitting up the arachnoid some of the coarser strands of the subarachnoid
tissue may be made out. The posterior and anterior nerve-roots will also be seen with the
ligamentum denticulatum between them. The connection of the latter with the pia
mater is well seen under water. The pia mater appears white and glistening, and when
traced downwards is very obviously continuous with the filum terminale. The last-named
structure stands out conspicuously among the duller-coloured nerve-roots which constitute
the cauda equina. On the anterior aspect of the cord the linea splendens will be seen.
Lastly the student should make a series of transverse sections through the cord and
compare the disposition of the grey and white matter in the different regions (fig. 439).
The DURA MATER forms a loose sheath or theca around the cord. It invests not
only the cord but also the elongated nerve-roots, which (under the name of cauda
equina) extend beyond the cord. It invests the cauda equina as far as the second
or third sacral vertebra, but at this level it converges so as to form a blunt hollow
cone, and is represented lower down only by the sheath of the filum terminale. By
means of this sheath it is attached to the base of the coccyx. Its outer surface is
FIG. 436.-VIEW OF THE MEMBRANES OF THE SPINAL CORD. (Ellis.)

Dura mater
Arachnoid
POSTERIOR ROOT
ANTERIOR ROOT-
Ligamentum denticulatum
Linea splendens-
Innige
rough and is loosely connected by fatty tissue to the ligaments and periosteum
which line the neural canal. Some stronger retinacula connect it to the posterior
common ligament. Its inner surface, smooth and shining, is separated from the
arachnoid by a narrow subdural space. It is connected to the cord by a special
development of the pia mater-the ligamentum denticulatum. It is continuous
through the foramen magnum with the supporting layer of the dura mater of the
brain. It sends tubular prolongations around the spinal nerves. These prolonga-
tions gradually merge into the connective tissue sheaths (epineurium) of the nerves.
Each tube is divided by a septum into two compartments, one for the anterior, and
one for the posterior root of the spinal nerve.
The differences between the dura mater of the brain and cord may be
summarised as follows:-The dura mater of the cord does not send processes or
infoldings into the fissures of the cord. It represents only the supporting layer
of the dura mater of the brain. The periosteal layer is represented by the periosteum

MENINGES OF THE SPINAL CORD
773
of the neural canal, but is separated from the supporting layer by fatty tissue,
and by some venous plexuses. Hence this periosteum is only brought into relation
with the dura mater proper by the fact, already noticed (page 712), that the dura
mater of the cranium is directly continuous by the medium of the posterior occipito-
axial ligament with the periosteum of the neural canal.
The ARACHNOID is separated from the dura mater by a narrow subdural space,
and is connected to the dura mater only opposite the attachments of the ligamentum
FIG. 437.-POSTERIOR VIEW OF THE MEDULLA OBLONGATA AND OF THE SPINAL CORD,
WITH ITS COVERINGS AND THE ROOTS OF THE NERVES. (Hirschfeld and Leveillé.)
MIDDLE
PEDUNCLE
INFERIOR
PEDUNCLE
CLAVA
C. 1.
3-'II
SUPERIOR PEDUNCLE
OF THE CEREBELLUM
SULCUS LONGITUDI-
NALIS MEDIUS
-GLOSSO-PHARYNGEAL
VAGUS
SPINAL ACCESSORY
IX.-
X.-0
XI.
B


Ligamentum
III.
denticulatum
POSTERIOR
LONGITUDINAL
XII.
IV.
CONUS
FISSURE
MEDULLARIS
V.
res
VI.
VII.
VIII.
bb saw L. 1-
II.
T. I.
-AN ANTERIOR ROOT
III.
II.
-A POSTERIOR ROOT
III.
IV.-
V.
VI..
VII.
VIII.-
IV.-
V..
S. I.
II.
III.
IV.-
FILUM
TERMINALE,
SURROUNDED
BY CAUDA
EQUINA
GANGLION
ON A
POSTERIOR
ROOT
denticulatum, to be presently described. It is a thin membrane resembling the
cerebral arachnoid, with which it is continuous. It sends tubular investments
along the nerve-roots. These investments eventually become continuous with the
perineural sheaths of the nerves. It extends downwards within the theca as far
as the second or third sacral vertebra, forming a common investment to the bundle
of nerve-roots constituting the cauda equina.

774
CLARO THE NERVOUS SYSTEM
The subarachnoid tissue is much less abundant in the spinal portion than in
the cerebral part of the subarachnoid space. It passes from arachnoid to pia
mater in the form of delicate threads, which are separated from one another by
comparatively wide intervals. It also gives support to the nerve-roots as they
cross the subarachnoid space (fig. 435). An incomplete membranous septum, the
septum posticum (Key and Retzius), passes from arachnoid to pia mater opposite
the posterior fissure of the spinal cord, and serves to conduct blood-vessels to
the cord. The space is also partially divided into a posterior and an anterior
compartment by the ligamentum denticulatum.
The PIA MATER of the cord consists of two layers, an outer and an inner, the
latter of which represents, and is continuous with, the pia mater of the brain.
Both layers dip into the anterior fissure of the cord, but only the inner layer enters
the posterior fissure. The outer layer is strong and fibrous, and presents certain
localised thickenings which require separate description; these are the ligamentum
denticulatum and the linea splendens. The filum terminale may be conveniently
described along with these.
The ligamentum denticulatum is a fibrous band which is attached on each side
of the cord about midway between the anterior and posterior nerve-roots. It is
continuous by its inner margin with the pia mater. Its outer margin is character-
istically scalloped or denticulated, and presents about twenty-one pointed processes
by which it is attached to the dura mater. These processes do not pierce the
arachnoid, but receive funnel-shaped sheaths from it (Key and Retzius). The
highest of these processes is at the level of the foramen magnum, and is placed
between the hypoglossal nerve and the vertebral artery. In the upper region of
the cord one denticulation is regularly placed between the point of exit of each
nerve and the next nerve below; lower down the arrangement becomes less regular.
It is continuous below with the filum terminale. The linea splendens (Haller) is
a conspicuous linear thickening which is placed in the middle line in front of the
cord. It presents a silvery white appearance. It is continuous below with the
filum terminale. The filum terminale is the continuation of the pia-matral sheath
of the cord, and contains but little nervous matter in its interior. It is easily
distinguished by its shining white appearance from the nerve-roots among which it
lies. It is a slender strand which extends from the pointed lower extremity of the
spinal cord to the lower end of the sacrum, or first piece of the coccyx, opposite
which it is attached to the bone. As already mentioned, it receives a sheath from
the dura mater in the lower part of its course.
EXTERNAL CHARACTERS OF THE SPINAL CORD
The spinal cord is about eighteen inches in length, and forms (by weight) about
two per cent. of the cerebro-spinal axis. It is cylindrical in form, and is slightly
compressed from before backwards, so that the transverse exceeds the antero-
posterior diameter. It is continuous with the medulla oblongata above at the
decussation of the pyramids; below it tapers off into a cone, the conus medullaris,
the apex of which is continued downwards by the filum terminale. It follows the
curvatures of the canal in which it is placed, and therefore describes two curves,
the upper or cervical convex forwards, and the lower or dorsal concave forwards.
In two regions of the cord distinct enlargements are visible: these are called
the cervical and the lumbar enlargements. The large size of the nerves which are
given off to supply the limbs, forming the brachial and lumbo-sacral plexuses,
obviously account for these enlargements of the cord. The increase in size is
almost entirely produced by an increase in the transverse diameter. The cervical
enlargement is more pronounced than the lumbar swelling. It commences at the
level of the third cervical vertebra, and ends at the second dorsal. It is at its maximum
THE SPINAL CORD
775
FIG. 438.-ANTERIOR AND POSTERIOR VIEW OF THE SPINAL CORD.
(Modified from Quain.)
X represents the filum terminale.


CLAVA
FUNICULUS CUNEATUS
POSTERIOR
LONGITUDINAL
FISSURE
OLIVARY BODY
LATERAL COLUMN
-DECUSSATION OF
PYRAMIDS
ANTERIOR
LONGITUDINAL
FISSURE
POSTERO-LATERAL
GROOVE
ANTERO-LATERAL
GROOVE
POSTERO-LATERAL
GROOVE
POSTERIOR
LONGITUDINAL
FISSURE
X.
ANTERIOR
LONGITUDINAL
FISSURE
776
THE NERVOUS SYSTEM
at the level of the sixth cervical vertebra. The lumbar enlargement commences
at the level of the ninth dorsal vertebra, and reaches its maximum at the twelfth
dorsal; below this point it rapidly diminishes and passes into the conus medullaris.
The spinal cord is bilaterally symmetrical, the two halves being marked off from
one another by the anterior and posterior longitudinal fissures. From the antero-
lateral and postero-lateral aspects of the cord the anterior and posterior nerve-roots
emerge, forming two parallel series of fasciculi which extend for the entire length
of the cord. In the upper cervical region the intrathecal course of the nerve-roots
is very short, and the direction taken by the roots is nearly transverse. As the
roots are traced downwards in the dorsal and lumbar regions, they become pro-
gressively longer, and descend with an increasing degree of obliquity. Hence the
lumbar and sacral nerve-roots have a very long intrathecal course. They extend
beyond the termination of the cord (which, it will be remembered, ends at the
body of the second lumbar vertebra), and lie within the theca in a sheaf somewhat
resembling a horse's tail, and therefore called the cauda equina.
Fissures. The anterior longitudinal fissure (fissura longitudinalis anterior) is
a true fissure and is comparatively wide. It attains a depth equal to one-third of
the antero-posterior diameter of the cord. As above mentioned, both layers of the
pia mater dip into it. It occupies the entire length of the cord. It is continuous
above with the anterior fissure of the medulla, being, however, almost obliterated
at the decussation of the pyramids. The posterior longitudinal fissure (sulcus
longitudinalis posterior) is much narrower than the anterior, and is, in fact, a
septum rather than a fissure, being formed by the inner layer of the pia mater,
which dips in and reaches as far forwards as the grey commissure. Its depth is
one-half of the antero-posterior diameter of the cord. It is continuous with the
posterior fissure of the medulla. Antero-lateral and postero-lateral fissures or
grooves corresponding to the line of origin of the anterior and posterior nerve-roots
are described, and by means of these fissures the cord is mapped out into three
columns: an anterior between the anterior longitudinal fissure and the antero-
lateral groove; a lateral between the last-named groove and the postero-lateral
groove, and a posterior between the postero-lateral groove and the posterior median
fissure. The postero-lateral groove is well marked; at its floor the grey matter
of the cord comes to the surface, and from it the fibres of the posterior roots
emerge in a single row. It is deepest in the cervical region, and is continuous with
the sulcus lateralis dorsalis of the medulla. The antero-lateral groove has no real
existence, as the anterior roots leave the cord in three to eight thin bundles, and
thus cover a longitudinal strip of the cord about one millimetre in breadth. In
correspondence with this, we find that the division into anterior and lateral
columns is also artificial, and it is now generally recognised that it is better to
enumerate only two columns in the spinal cord, viz. an antero-lateral and a
posterior. In the cervical region of the cord an additional groove (sulcus para-
medianus dorsalis) is visible; this becomes indistinct when traced downwards, but
is very obviously continued into the medulla.
The surface of the cord is clothed with white matter, the grey matter being
contained in the interior. In two situations, however, the grey matter comes to
the surface, viz. in the floor of the postero-lateral groove and at the bottom of the
posterior longitudinal fissure. In the latter situation the posterior grey commissure
crosses from side to side.
INTERNAL STRUCTURE OF THE SPINAL CORD
In transverse section each lateral half of the cord is seen to be composed of
both grey and white matter, the latter being disposed on the surface. The grey
matter is in the form of a crescent, which has been not inaptly compared (by Testut)
THE SPINAL CORD
777
to a large comma (,). The head of the comma looks forwards and constitutes the
anterior horn of grey matter; the tail forms the posterior horn, and the convexity
looks inwards and is united to the grey crescent of the opposite side by the grey
commissure. The two crescents, with the commissure, form a figure resembling a
capital H. Within the grey commissure is the central canal of the cord, and in
front of the grey commissure, occupying the floor of the anterior longitudinal
FIG. 439.-SECTIONS THROUGH DIFFERENT REGIONS OF THE SPINAL CORD.
(After Schwalbe.)

POSTERIOR ROOTS
ANTERIOR ROOTS
POSTERIOR FISSURE.
ANTERIOR FISSURE
A. At the level of the sixth
cervical nerve-roots.

B. At the mid-dorsal region.

CENTRAL CANAL-
C. At the centre of the lumbar
enlargement.
D. At the upper part of the conus
medullaris.

E. At the level of the fifth sacra
nerve-roots.
F. At the level of the coccygeal
nerve-roots.
fissure, is the anterior white commissure. Medullated fibres cross the middle line
both in the white and in the grey commissure. The term commissure is somewhat
misleading, as the majority of the nerve-fibres which pass from side to side are not
commissural but decussating fibres.
The grey matter of the cord consists of two varieties: (a) Substantia gelatinosa,
and (b) substantia spongiosa. The former (a) covers the head of the posterior
horn like a cap (substantia gelatinosa Rolandi), and is also found around the
778
THE NERVOUS SYSTEM
central canal (substantia gelatinosa centralis). The latter is continued into the
ependyma of the cerebral ventricles. (b) The substantia spongiosa is much more
extensive than the substantia gelatinosa, and contains large nerve-cells. These
cells are arranged in definite groups. In the anterior horn there are large cells
which are connected with the anterior roots, and are called motor-cells. In the
lower lumbar region these motor-cells are disposed in four groups: a central
(occupying nearly the centre of the anterior horn), a mesial, a latero-ventral, and
a latero-dorsal. The latero-dorsal group represents the lateral horn (tractus
intermedio-lateralis). The lateral horn is represented throughout the cord, but is
best seen in the upper dorsal region where it projects like a beak. It is to be
distinctly understood that these groups of cells are the expression in cross-section
of long columns of cells which are placed longitudinally in the grey matter. In
the dorsal region of the cord a very remarkable column of cells (Clarke's column)
is found. It occupies the inner side of the base of the posterior horn. It com-
mences opposite the origin of the seventh or eighth cervical nerve, and disappears
at the level of the second or third lumbar. It is at its maximum opposite the
eleventh or twelfth dorsal nerve. It is encircled and as it were mapped out by
fibres belonging to the posterior roots. In the cervical region, immediately behind
the lateral horn, trabeculæ of grey matter extend outwards for a short distance,
and enclose strands of white fibres in their meshes. This network is called the
processus reticularis.
The central canal of the cord is lined by ciliated epithelium; it is continued
into the filum terminale for about half the length of the latter, and is here some-
what dilated; a few nerve-fibres accompany the canal into the filum terminale, and
are supposed to be rudimentary coccygeal nerves. The canal is dilated in the
conus medullaris, forming an irregular cavity, the sinus rhomboidalis inferior, or
ventriculus terminalis.
In transverse sections through the spinal cord made in the dissecting room the general
arrangement of the grey and white matter can be made out, and sections from the different
regions of the cord can be distinguished from one another in fresh specimens, especially
with the aid of a pocket lens.
In the upper cervical region (at the level of the second or third cervical nerves) the
grey matter forms an H-shaped outline bearing a great resemblance to the outline in the
dorsal region (fig. 439, B). Sections through this region are very difficult to distinguish from
sections of the dorsal cord with the naked eye. The microscope, however, reveals the absence
of Clarke's column and the presence, in some cases, of root-fibres of the spinal accessory

nerve.
In the lower cervical region (fig. 439, A) the cord is elliptical in outline and the anterior
horns of the grey crescents are very large; the section shows a certain similarity to a section
through the lumbar region (fig. 439, C). In the latter, however, the anterior horns are
more evenly rounded, the general outline approaches more nearly to a circle, and the
proportion of grey to white matter has greatly increased.
Sections of the dorsal region can be easily recognised with the microscope by the
presence of Clarke's column, which is confined to the dorsal, lowest part of the cervical,
and the uppermost part of the lumbar regions.
Sections through the part of the cord from which the sacral nerves arise show a great
preponderance of grey matter. This feature becomes more marked as the termination of
the cord is approached (fig. 439, D, E, and F).
DEEP ORIGIN OF THE SPINAL NERVES
The deep origins of the spinal nerves are (undoubtedly in the case of the anterior
roots, and possibly also in the case of the posterior roots) from nerve-cells embedded
in the grey matter of the cord. Only the principal connections of the roots are
described here; other connections which are still doubtful are, for the sake of
simplicity, omitted. But little can be learned regarding the course of these nerve-
roots from the normal adult cord, and the facts detailed here have been chiefly
ascertained by embryological and pathological research. The success of the
SPINAL NERVES
779
embryological method depends upon the fact that certain tracts or groups of fibres
myelinate (or acquire their medullary sheath) at an earlier period than others, and
therefore these tracts of medullated fibres can be followed and recognised through
a series of sections. The pathological method depends upon the trophic influence
exercised by nerve-cells. It is found that every nerve-fibre must receive a certain
influence from a nerve-cell in order to benefit by the lymph with which it is
surrounded. This is called trophic influence. The trophic cells for the sensory
fibres are situated in the ganglia in the posterior roots; hence, if the roots be
divided between the cord and the ganglia, the nerve-tracts degenerate in an upward
direction, and the degenerated tracts can be seen surrounded by the unaffected
tracts. Ascending degeneration is, therefore, characteristic of centripetal tracts.
The trophic cells for the motor fibres, however, are situated in the cerebral cortex;
hence injuries of the motor area of the cortex are followed by descending degenera-
tion of the motor tracts of the spinal cord. In speaking of the deep origin of the
spinal nerves in the cord, it is to be understood that we refer to the interruption of
the nerve-fibres in nerve-cells; from the nerve-cells other fibres arise in a manner
not yet fully understood, and these fibres proceed upwards in the white columns of
the cord to the brain.
It is easy to recognise, particularly in the case of motor nerves, that the aggre-
gations of nerve-cells in the cord correspond to, or are serially homologous with, the
nuclei of the cranial nerves. In each case we have an interruption, in nerve-cells,
of fibres proceeding from the cerebral cortex towards the periphery of the body.
Just as injury to the anterior moiety of the posterior limb of the inner capsule will
paralyse the motor fibres of the spinal nerves of the opposite side of the body, so
will injury to the genu of the inner capsule paralyse the motor cranial nerves of
the opposite side. The same remarks hold good in regard to the corresponding
areas of the cortex.
The anterior roots of the spinal nerves traverse the white matter of the cord
in several bundles, and enter the anterior horn of grey matter. Some fibres
(1) join cells, and eventually pass to the lateral pyramidal tract of the same side.
Others (11), after a similar interruption, pass to the anterior pyramidal tract of the
same side. Others (III) pass, via the anterior commissure, to cells in the anterior
horn of the opposite side. Lastly, others (IV) pass to the cells of the lateral horn
(fig. 440).
The posterior roots enter the cord at the postero-lateral groove, and spread out
in the following manner :-The most laterally placed fibres (v) pass upwards for
a short distance in the boundary zone of Lissauer, and then enter the posterior
horn; the intermediate fibres (VI) pierce the substantia gelatinosa Rolandi, and
are continued in a manner not yet fully understood; the innermost fibres (VII)
enter Burdach's columns, and run upwards for a short distance in a longitudinal
direction. From thence they are very probably continued as follows:-Some (VIII)
pass into nerve-cells in the posterior horn; others (IX) pass, via the posterior
commissure, into Goll's column on the opposite side; others (x) enter Clarke's
column, and, after an interruption in the nerve-cells of the column, pass into the
direct cerebellar tract of the same side; lastly, others (x1) enter Goll's column on
the same side.
Tracts of the spinal cord. The accompanying diagram (fig. 440) indicates the
position and general relation of those tracts, but it must be understood that they
vary somewhat in different regions of the spinal cord. For instance, the anterior
pyramidal tract is not found below the lower part of the dorsal region, and the
direct cerebellar tract disappears at the level of the upper lumbar nerve-roots. In
the antero-lateral column in the following tracts are found: anterior pyramidal,
anterior ground bundle, mixed lateral zone, Gower's tract, lateral ground bundle,
lateral pyramidal tract, direct cerebellar tract. To these may be added the boundary




780
THE NERVOUS SYSTEM
zone of Lissauer. In the posterior column, two tracts-the columns of Goll and
Burdach-are found.
We shall now proceed to trace these tracts towards the brain. As some of them
are centripetal and some centrifugal, it would appear more scientific to trace the
former brainwards and the latter towards the periphery, following the course of the
nerve-current in each case. As, however, the functions and connections of some of
these tracts are very imperfectly known, it will be more convenient to trace all of
them in an upward, or cerebral, direction, more especially as, while they are tolerably
clearly marked off in the spinal cord, their connections become very complicated
when they enter the brain.
The pyramidal tracts are the best defined in their course and connections, and
may be described first. The larger or lateral pyramidal tract is placed in the
FIG. 440.-DIAGRAM OF THE TRACTS OF THE SPINAL CORD AND OF THE DEEP
ORIGINS OF THE SPINAL NERVES.
The motor tracts are indicated by red shading, the sensory by blue. I, II, III, IV, anterior root;
V, VI, VII, posterior root.
BURDACH'S COLUMN
SUBSTANTIA GELATINOSA ROLANDI
BOUNDARY ZONE OF LISSAUER
LATERAL PYRAMIDAL TRACT
DIRECT CEREBELLAR
TRACT
קוח
GOLL'S COLUMN
IX
XI
II
VII
VI
V
I
X
VIIL
IV
ANTERIOR GROUND BUNDLE
GOWER'S TRACT
MIXED LATERAL ZONE AND
LATERAL GROUND BUNDLE
IV
(SENSORY PORTION)
II
LATERAL GROUND BUNDLE
III
I
(MOTOR PORTION)
ANTERIOR PYRAMIDAL
TRACT
hinder part of the lateral column. The anterior pyramidal tract, very much the
smaller, forms the innermost part of the anterior column. The fibres of the ante-
rior nerve-roots, on entering the cord, suffer an interruption in the ganglion cells
of the anterior horn of grey matter, but afterwards pass into the lateral pyramidal
tract. The greater number ascend in this tract as far as the decussation of the
pyramids, but a certain (variable) number pass through the anterior white com-
missure to the opposite side of the cord, and ascend in the anterior pyramidal tract.
At the decussation of the pyramids the fibres of the lateral pyramidal tract pass
to the opposite side in coarse bundles, cutting through the neck of the anterior horn
of grey matter, and join the fibres of the anterior pyramidal tract, which, it will be
remembered, have already decussated, vid the anterior commissure, lower down.
Thus all the fibres derived from the anterior roots pass to the opposite side of the
body. It is right to mention, however, that 'recrossed fibres' have recently been
described by Sherrington-that is to say, fibres which, having decussated vid
TRACTS OF THE SPINAL CORD
781
the anterior commissure, cross a second time at the pyramidal decussation, and
thus regain the side of the body from which they originally started. The two
tracts, now united, form the pyramidal body, and ascend as a compact bundle as
far as the pons Varolii. They then traverse the latter structure in the form of
flattened fasciculi separated from one another by the transverse fibres of the pons.
Then they emerge at the upper border of the pons, and pass upwards in the
crusta of the crus cerebri forming about the middle third of that body. From
thence they pass through the anterior moiety of the posterior limb of the inner
capsule, and end in the Rolandic area; that is to say, in the paracentral lobule, the
ascending frontal, and the ascending parietal convolutions.
The anterior ground bundle and the mixed lateral zone may be described
together, as their connections are similar, and they are only mapped off from one
another by the fibres of the anterior roots, which cut through them. Taken thus
together, they may be said to consist of fibres belonging to the anterior roots and
of longitudinal commissural fibres. The latter fibres unite the groups of motor
cells of different levels in the anterior horn with one another. Traced into the
medulla, the anterior ground bundle gradually recedes from the surface as it
becomes overlapped by the pyramidal body. Its fibres pass backwards, outwards,
and upwards through the substance of the medulla, and then bend inwards towards
the middle line and form the most dorsal portion of the substantia reticularis
alba. The anterior ground bundle appears to be continuous with the posterior
longitudinal bundle. The latter forms longitudinal communications between the
nuclei of the facial and the eye-muscle nerves, and thus resembles the anterior
ground bundle in uniting together a series of motor nuclei. The mixed lateral
zone also passes into the substantia reticularis alba, forming its middle portion.
Gower's tract is regarded as a centripetal tract. It is probably formed by
fibres from the posterior roots of the spinal nerves, which cross in the posterior
commissure, and then, after suffering an interruption in nerve-cells, ascend in the
tract above mentioned. A portion of it appears to be lost in the cervical region of
the cord. The rest passes to the nucleus lateralis of the medulla, and, after a
partial or total interruption in the cells of that nucleus, passes on to form the
external part of the tract of the fillet.
The direct cerebellar tract, as already mentioned, commences at the level of the
upper lumbar nerve-roots and augments as it ascends. It is formed of fibres
chiefly uncrossed. These fibres are derived from the posterior roots which have
suffered an interruption in the nerve-cells of Clarke's column. It ascends as a
well-defined tract on the outer surface of the lateral pyramidal tract as far as the
medulla; here it passes obliquely across the descending root of the fifth nerve and
reaches the posterior surface of the medulla, where it joins the restiform body and
thus passes to the superior vermis of the cerebellum. A certain number of the
fibres, according to Monakow, do not join the restiform body but ascend in the
tract of the fillet as far as the upper part of the valve of Vieussens, and then bend
downwards and decussate in the substance of the valve and pass also to the
superior vermis.
The lateral ground bundle is a mixed tract. The motor fibres occupy the
anterior and larger part, and are derived from the anterior horns. The sensory
fibres, forming the posterior part of the tract, have probably the following deriva-
tion. Some of the fibres of the posterior roots, after suffering an interruption in
the cells of Clarke's column, enter the posterior columns and ascend for a very
short distance in Burdach's column. They then pass obliquely through the grey
matter of the posterior horn to form the sensory part of the lateral ground bundle.
A few fibres may pass via the posterior commissure to the corresponding bundle
on the opposite side. The bundle then ascends as far as the medulla, where its
fibres, at a point immediately above the pyramidal decussation, cross over to the


782
THE NERVOUS SYSTEM
opposite side, entering into the sensory or superior pyramidal decussation (decus-
satio lemnisci). From thence it ascends brainwards.
The boundary zone of Lissauer is formed by the most lateral fibres of the
posterior roots, which ascend for a short distance in that zone, and then leave it to
enter the posterior horn.
Burdach's column contains (a) sensory fibres from Clarke's column; (b) root
fibres from the posterior roots; and (c) longitudinal commissural fibres. (a) The
fibres from Clarke's column have already been described in connection with the
lateral ground bundle. They are derived from the posterior roots, ascend only for
a very short distance in Burdach's column, and leave it again to join the posterior
or sensory part of the lateral ground bundle. (b) The fibres which are directly
derived from the posterior roots pass upwards; some enter Goll's column, others
ascend to the nucleus cuneatus in the medulla. These fibres, after suffering
an interruption in the nerve-cells of the cuneate nucleus and nucleus of the clava,
divide into two groups; one group decussates at the decussatio lemnisci, and goes
to swell the tract of the fillet; the other goes to the restiform body, chiefly in the
form of arciform fibres. (c) The longitudinal commissural fibres originate and
terminate in the grey matter of the posterior horns, and thus unite groups of nerve-
cells occupying different levels in the spinal cord.
Goll's column is formed of longitudinal commissural fibres similar to the set (c)
in Burdach's column, inasmuch as they unite groups of nerve-cells which are
placed at different levels in the posterior horns. They differ from the fibres
in Burdach's column, however, by the fact that the individual fibres are very long.
Goll's column diminishes in size when traced downwards, and is feebly represented
in the portion of the cord from which the sacral nerves arise. The ultimate source
of its fibres is from the posterior roots, which reach it in a manner not yet fully
understood. It terminates above in the nucleus of the clava, from whence fibres
pass to the tract of the fillet and to the restiform body in the manner already
noticed in the description of Burdach's column.
Having now described the course of the tracts in the spinal cord, and the more
direct continuation of these tracts into the brain, it will be necessary to recapi-
tulate the constitution of some of the best defined of the groups of fibres and which
proceed to the cerebrum and cerebellum, namely, the fillet, the posterior longitudinal
bundle, and the restiform body.


-
Fillet. The term fillet (lemniscus) was originally applied to the triangular
band of fibres which comes to the surface at the lateral groove of the mesen-
cephalon and winds round the superior cerebellar peduncle to disappear (as far as
macroscopic observation is concerned) in the region of the testes. The system of
fibres to which this superficial set belongs is now known as the inferior or lateral
fillet (fig. 425), while other fibres, more deeply placed, form the superior or mesial
fillet. The superior fillet is in part derived from the columns of Goll and Burdach
of the opposite side; these fibres, after an interruption in the nerve-cells of the
clavate and cuneate nuclei, pass across at the decussatio lemnisci. The continuation
of Gower's tract applies itself to the outer side of these fibres, and thus a broad
band of fibres, the tract of the fillet, is formed. It is very conspicuous in trans-
verse sections through the pons (fig. 429). The innermost part bends downwards
into the crusta of the cerebral peduncle, and passes from without inwards to
form the outermost constituent of the crusta. The remaining and by far the
larger part of the tract passes upwards, occupying the most ventral portion of the
tegment of the lower part of the mesencephalon, and then, assuming a more dorsal
position, encloses the nucleus of the superior quadrigeminal body of the same side,
some fibres crossing in the raphe to enter, with a similar relation, the superior
quadrigeminal body of the opposite side. Other fibres are described which pass
brainwards on the outer side of the red nucleus. Some of these fibres end in the

RESTIFORM BODY-FIBRES OF CEREBELLUM
783
optic thalamus, while others probably pass to the cortex cerebri via the inner
capsule. The inferior fillet arises chiefly in the pons from the superior olive and
from the nucleus of the inferior fillet. The latter is a collection of nerve-cells
which is placed close to the cerebral end of the superior olive. The inferior fillet
comes to the surface at the lateral groove of the mesencephalon as above described,
and then encloses the nucleus of the testis. A portion of it decussates above the
aqueduct of Sylvius to reach the testis of the opposite side.
Many additional fibres have been said to join the fillet; in particular, fibres from the
anterior column may be mentioned (Homan and Spitzka).
The posterior longitudinal bundle may be regarded as the cerebral continua-
tion of the anterior ground bundle of the cord. It is generally believed to establish
communications between the nuclei of the eye-muscle nerves. Its connection with
the facial nerve is described in the account of the anatomy of that nerve (page 810).
The restiform body is the continuation of the direct cerebellar tract together
with fibres from the columns of Goll and Burdach. Its connection with these
columns is partly crossed, partly uncrossed. The uncrossed fibres have been
shown to take a larger share in the formation of the restiform body than the
crossed fibres (Darkschewitsch and Freud). The crossed fibres all reach the
restiform body as arciform fibres; many of these fibres traverse the olivary nucleus
but without entering into connection with its nerve-cells (Edinger); they also
traverse the accessory olives and may pierce the ascending root of the trigeminal
nerve; they all decussate at the raphe, and from thence proceed in two groups,
superficial and deep arciform fibres. The superficial arciform fibres emerge
through the anterior fissure of the medulla, some also through the sulcus
paramedianus ventralis, and arch round the pyramidal body and olive to join the
restiform body. In this part of their course they pass between the root-fibres of
the ninth, tenth, eleventh, and twelfth nerves. The deep arciform fibres, after
crossing in the raphe, traverse the olivary nucleus of the opposite side, and pass
from thence, through the substance of the medulla, into the restiform body.
The olivary body also sends fibres to the restiform body. Fibres pass out of
the hilum and cross in the raphe; they then traverse the olivary body of the
opposite side and join the restiform body.
The fibres of the cerebellum may be described under the following heads:
(a) Fibres derived from the cerebellar peduncles, and (b) intrinsic fibres. (a) The
fibres from the pons (middle peduncle) are, as already described (page 760), partly
true commissural fibres, and partly fibres which establish (with or without the
intervention of nerve-cells) a crossed connection between the cerebrum and
cerebellum. The upper fibres of the pons pass into the lateral parts of the
cerebellar hemispheres, and end in the grey cortex. The middle fibres sweep
downwards, forming the oblique fasciculus, and end in the folia of the inferior
surface. The lower fibres accompany the restiform body to the superior surface.
The restiform body (inferior peduncle) is joined on entering the cerebellum by the
inferior fibres of the pons; the two together unite into a distinct round bundle, the
inner part of which is formed by the restiform body; the outer by the pons-fibres.
This bundle passes through a distinct gap or interval bounded by the superior
peduncle internally, and by the greater part of the middle peduncle externally. Its
fibres then spread out into a layer (fibræ semicirculares of Stilling), which are
disposed in gentle curves convex backwards and outwards; these fibres cover the
capsule of the corpus dentatum, and finally sweep abruptly upwards into the folia
of the superior vermis. Some fibres enter the nucleus fastigii.



6
The corpus dentatum is covered by a distinct capsule of fibres (the fleece' of
Stilling) derived from the olivary nucleus of the opposite side. The fibres are
probably for the most part interrupted in the nerve-cells of the corpus dentatum,

784
THE NERVOUS SYSTEM
and are then (indirectly) continued into the white matter which occupies the
interior of that plicated bag of grey matter. From the hilum of the corpus
dentatum a bundle of fibres passes out, which is joined by fibres from the fleece,
and thus the superior cerebellar peduncle is formed. The superior cerebellar
peduncle passes upwards and inwards, and receives a covering on its outer side
from the inferior fillet. It disappears from the surface by passing under cover of
the testis of its own side, and assumes a deeper position in the mesencephalon,
passing to the ventral side of the aqueduct of Sylvius. It decussates with its fellow
of the opposite side, the decussation being most pronounced at the level of the
centre of the nates. The decussation being completed, each peduncle proceeds
brainwards as a distinct column. This column of fibres soon encounters the red
nucleus, and the fibres pass through the nucleus in small bundles, the cross-section
of which gives the punctated appearance to the red nucleus which is so charac-
teristic of that body when seen in coronal section. Beyond the red nucleus, fibres
of the superior peduncles certainly enter the optic thalamus, and probably the
globus pallidus and the cortex cerebri.
(b) Sagittally-directed fibres are placed within the superior vermis. When
traced forwards these fibres are found to decussate with their fellows of the
opposite side in front and above the nucleus fastigii; here they are joined by true
commissural fibres from its hemispheres, the whole forming the great anterior
cerebellar commissure of Stilling.
Fibres unite the different folia to one another, constituting a system of fibres
which form the most peripheral part of the arbor vitæ. These fibres, from their
general arrangement, are called garland-like fasciculi.
Nerve-tracts in the substance of the thalamencephalon and prosencephalon.--
The systems of fibres which are connected with the optic thalamus may be first
considered; the principal of these are: (a) The posterior commissure; (b) the
corona radiata of the optic thalamus; and (c) the bundle of Vicq d'Azyr.
(a) The posterior commissure undoubtedly contains a tract of fibres which passes
from the optic thalamus to the tegmental region of the mesencephalon on the
opposite side; but beyond this, nothing is known with any degree of certainty. It
is said to transmit fibres from the fillet and from the posterior longitudinal bundle
to the opposite side. Fibres are also said to proceed via this commissure from the
ganglion habenula and the pineal body to the oculo-motor nucleus of the opposite
side. It is therefore a bundle of decussating fibres derived from various sources,
and probably does not contain any true commissural fibres.
(b) The corona radiata of the optic thalamus is formed of a system of fibres
which converge to the thalamus from the cortex of the frontal, parietal, occipital,
and temporal lobes, and it also receives a small bundle from the cortical part of the
olfactory tract. Portions of this system, namely, the fibres from the occipital lobe
(posterior peduncle of the thalamus), and from the temporal lobe (inferior peduncle),
require special notice. The posterior peduncle of the thalamus (optic radiation)
passes backwards in the white matter of the hemisphere in company with a great
bundle of sensory fibres to the occipital lobe. It is further described in connection
with the optic nerve (page 790). The inferior peduncle may, for the sake of
simplicity, be described with the ansa peduncularis, as it forms an important
constituent of that body.
The ansa peduncularis may be exposed from the base of the brain by dissecting
the optic tract from the surface of the crus cerebri. It is a band of fibres which
winds round the ventral surface of the crusta just at the transition of the latter
into the inner capsule. Its principal constituents are the ansa lenticularis and
the inferior peduncle of the thalamus. The ansa lenticularis proceeds from the
medullary laminae of the lenticular nucleus and passes transversely inwards
immediately below the globus pallidus. It then enters the subthalamic region, and
CORONA RADIATA
785
without doubt passes into the mesencephalon, but its exact course cannot be followed
with certainty. The inferior peduncle of the thalamus is partly formed by a
sagitally-directed bundle which passes backwards through the substance of the
thalamus between the anterior pillar of the fornix and the bundle of Vicq
d'Azyr. This bundle is joined by fibres from the superior surface of the thalamus
(stratum zonale). The fibres from the stratum zonale pass from the superior to the
internal surface of the thalamus, and finally, reaching the inferior surface of that
body, join the sagittal bundle first mentioned to form the inferior peduncle; the
latter now passes outwards below the ansa lenticularis and ends in the cortex of
the temporal lobe.
(c) The bundle of Vicq d'Azyr passes from the anterior tubercle of the
thalamus to the nucleus of the corpus albicans. It might be regarded as a consti-
tuent of the corona radiata--the nucleus of the corpus albicans being considered as
modified cortex.
The white matter of the cerebral hemispheres contains the following systems
of fibre: (a) The corona radiata; (b) commissural or interhemispheric fibres;
(c) association or intrahemispheric fibres. These three systems of fibres are
disposed in more or less defined tracts which can be unravelled by dissection, but
in certain situations where the different tracts cross one another the arrangement
becomes more complicated. This is notably the case in the region where the fibres
of the corpus callosum intersect the fibres of the inner capsule.
The corona radiata is the name given to the prolongation of the fibres of the
inner capsule into the hemisphere. It is continued upwards from the inner capsule
as a somewhat narrow band (peduncle of the corona radiata), but the fibres soon
spread out like a fan and proceed to the cerebral cortex. It will be well at this
stage to re-examine the constitution of the inner capsule; the latter contains three
sets of fibres, namely: (a) Fibres which pass from the crusta of the crus cerebri
directly into the corona radiata without the intervention of nerve-cells; (b) fibres
passing from the mesencephalon into the optic thalamus and corpus striatum; and
(c) fibres from the thalamus (part of the corona radiata of that body); and from
the corpus striatum to the cerebral cortex. We have already seen (page 742) that
the inner capsule shows in horizontal section an anterior limb, a posterior limb
and a genu. The fibres which occupy the most anterior part of the anterior limb
belong to the corona radiata of the optic thalamus. Behind these fibres is a tract
which extends nearly to the genu; this tract is formed by fibres which are derived
from the frontal lobe, and although their function is not accurately known they
are supposed to be associated with the higher intellectual functions. Traced down-
wards, this bundle passes into the crusta, forming rather more than the inner fifth
of that body, and from thence enters the pons, where a part of it seems to terminate
(frontal pontine tract). Its further course is unknown. The portion of the inner
capsule immediately in front of the genu is intimately associated with the faculty
of speech; it passes in the crusta immediately external to the frontal pontine tracts.
The genu conveys fibres from the cortex cerebri to some of the motor cranial
These fibres pass immediately external to the preceding (aphasia) bundle,
and probably decussate in the pons to become connected to the nuclei of the facial
and hypoglossal nerves, and to the motor nucleus of the trigeminal. The anterior
two-thirds of the posterior limb of the inner capsule is formed by the pyramidal
tract which has already been sufficiently described (page 780). The posterior third of
the posterior limb of the inner capsule is formed by sensory fibres comprising the
optic radiation; the latter proceeds exclusively from the occipital lobe. The
remaining sensory fibres are derived from the occipital and temporal, and to
a certain extent from the parietal, lobes. They descend in the crusta, occupying
the outer third of that body. As this sensory tract traverses the crusta, its outer-
most part is formed by fibres derived from the fillet (page 782).


nerves.
3 E

786
THE NERVOUS SYSTEM
The commissural system, consisting of the corpus callosum and the anterior
commissure, has been already described (pages 733, 742).
The intrahemispheric or association fibres unite different portions of the cortex
of the same hemisphere to one another. These fibres are in two sets-a long and a
short. The short fibres (fibræ arcuatæ seu propriæ) unite two adjacent convolu-
tions, the fibres passing round beneath the fissure which separates the two
convolutions. The long fibres are disposed in several more or less well-defined
tracts, namely: the cingulum, the fasciculus arcuatus, the fasciculus uncinatus,
the perpendicular occipital fasciculus, and the fasciculus longitudinalis inferior.
The cingulum is a well-defined band, which occupies the core of the gyrus
fornicatus. Near the splenium of the corpus callosum it receives an acces-
sion of fibres from the occipital lobe. The fasciculus arcuatus passes from the
cortex of the frontal to the occipital lobe; it also sends some fibres into the
temporal lobe. The fasciculus uncinatus springs from the orbital gyri and from
the inferior frontal convolution, and, after traversing the lower part of the
claustrum, ends in the cortex of the temporal lobe near the amygdaloid nucleus.
The perpendicular occipital fasciculus passes from the inferior parietal lobule to
the inferior occipito-temporal convolution. The fasciculus longitudinalis inferior
is an extremely well-defined bundle which passes from the occipital to the temporal
lobe.
The external capsule also belongs to the association system, as it is chiefly
concerned with the convolutions of the island of Reil.
THE PERIPHERAL NERVOUS SYSTEM
The cerebro-spinal nerves, together with the end-organs of these nerves, the
sympathetic system and the ganglia which are connected to both the cerebro-spinal
and the sympathetic nerves, make up the peripheral nervous system. The cerebro-
spinal nerves are invariably paired, and, with a few exceptions (notably the vagus),
are symmetrical in their origin, course, and distribution on the two sides of the body.
The cranial nerves arise directly from the brain and pass out from the skull
through foramina in the cranial wall. The spinal nerves arise by anterior and
posterior roots from the spinal cord, and leave the spinal canal by passing through
the intervertebral foramina. The first spinal nerve is somewhat exceptional, as its
origin is partly from the medulla, and, moreover, it leaves the spinal canal by
passing between the occipital bone and the atlas.
THE CRANIAL NERVES
The cranial nerves are classified into nine pairs by Willis, and into twelve pairs by
Soemmerring. Willis's classification depends upon the manner in which the nerves
pierce the dura mater; for example, the glosso-pharyngeal, vagus, and spinal
accessory nerves all pierce that membrane opposite the jugular foramen, hence
they collectively form a cranial nerve (the eighth) of Willis. In Soemmerring's
classification each nerve-trunk is considered separately. Willis's classification was
formerly in general use in this country; it is now, however, generally discarded in
favour of Soemmerring's classification. The latter will be followed in this work.
The following table will explain the relation of Willis's to Soemmerring's
classification:-
CRANIAL NERVES
787
Soemmerring
Names
Oculo-motor
Pathetic or trochlear
Trigeminal or trifacial
Willis
First pair of nerves
First pair of nerves
Olfactory
Second
Second
99
Optic
Third
Third
99
Fourth
Fourth
Fifth
Fifth
Sixth
Sixth
Seventh
Portio dura Seventh
1 Portio mollis Eighth
99
99
Ninth
99
Eighth
Tenth
22
Eleventh
وو
Ninth
Twelfth
99
99
Abducent
Facial
Auditory
Glosso-pharyngeal
Pneumogastric or vagus
Spinal accessory
Hypoglossal
It will be well to notice here that the olfactory and optic nerves are not serially
homologous with the other cranial nerves, but are rather outgrowths of the cerebral
FIG. 441.-SURFACE ORIGIN OF THE CRANIAL NERVES.
(After Allen Thomson.-Quain.)

OPTIC THALAMUS
OPTIC TRACT
TUBER CINEREUM.
POSTERIOR PER-
FORATED SPACE
CORPUS GENICU-
LATUM EXTERNUM
CORPUS GENICU-
LATUM INTERNUM
V
ISLAND OF REIL
PITUITARY BODY
IV
CORPORA
ALBICANTIA
CRUS CEREBRI
PYRAMIDAL BODY-
IXO
X
OLIVARY BODY-
XI
XII
ARCIFORM FIBRES
PONS VAROLII
GREAT HORIZONTAL
FISSURE
FLOCCULUS
SPINAL ACCESSORY
NERVE
FIRST CERVICAL NERVE-
ANTERO-LATERAL GROOVE OF-
SPINAL CORD
ANTERIOR COLUMN OF SPINAL
CORD
6
substance itself. The filaments of the olfactory nerve,' which pierce the cribriform
plate of the ethmoid bone, correspond collectively to a cranial nerve. In the case
of the optic nerve, the retina, as a study of its development shows, is a portion of
the brain extruded beyond the cranial wall, and the ganglionic layer of the retina
in all probability corresponds to the nucleus of origin' of an ordinary cranial nerve.
The nervous elements which intervene between the ganglionic layer of the retina
and the rods and cones therefore represent the true optic nerves.
3E2

788
THE NERVOUS SYSTEM
Superficial and deep origins.-The point at which a cranial nerve emerges from
the substance of the brain is called its superficial origin; while the collection of
nerve-cells to which its fibres can be followed is called its deep origin. It must be
clearly understood, however, that the deep origin is only the proximate origin of
the nerve, the real origin is in the cerebral cortex. For example, injuries to the
lower portions of the ascending parietal and ascending frontal convolutions almost
as surely paralyse the facial and hypoglossal nerves as if the nuclei of these nerves
had been destroyed in the medulla.
General distribution.-The olfactory, optic, and auditory nerves are exclusively
nerves of special sense, and are distributed to the nose, the eye, and the ear, respec-
tively. Of the remaining nerves, some are motor, others are mixed. The motor
nerves are the third, fourth, and sixth to the ocular muscles, the seventh to the
platysma and to the superficial muscles of the face, and the twelfth to the muscles
of the tongue. The mixed are the fifth, which is chiefly sensory to the face, teeth,
eye, external ear, and fore part of the scalp, but also motor to the muscles of masti-
cation; the ninth, which contains fibres for the special sense of taste, also ordinary
sensory and motor fibres; the tenth which conveys sensory fibres to the external
ear, and both motor and sensory fibres to the pharynx, larynx, heart, lungs,
trachea, œsophagus, and stomach; and the eleventh, which divides into a spinal
part, wholly motor, destined for the sterno-mastoid and trapezius muscles, and a
mixed or accessory part which joins the tenth.
In the following pages the course of each nerve is described in order from its
so-called deep origin to its peripheral distribution; the ultimate connection with the
cortex is described in the anatomy of the brain. An exception is made, however,
in the case of the olfactory and optic nerves, the cerebral connections of which
are described in this place.
FIRST OR OLFACTORY NERVES
The grey filaments, about twenty to thirty in number, which arise from the
under surface of the olfactory bulb, together constitute, as above noticed, the
olfactory or first nerve; the olfactory tract and bulb, formerly described as the first
nerve, being in reality a part of the brain. It will be convenient to describe the
tract and bulb first, and then to take the nerves at the point where they appear on
the surface of the bulb, and trace them to their central origin. The peripheral dis-
tribution will be afterwards described. The olfactory tract is an elongated body,
triangular in coronal section. It is covered at its anterior end by a cap of grey
matter, the olfactory bulb. Both tract and bulb occupy the olfactory sulcus on
the orbital surface of the frontal lobe. In the natural position the tract rests upon
the upper surface of the sphenoid bone, in front of the optic groove, while the bulb
is in contact with the cribriform plate of the ethmoid bone. The olfactory tract
contains in its interior a strand of connective tissue, which occupies the position
of the obliterated ventricular cavity (page 724); above this the tract is formed by
grey matter, the cortex of the tract. The latter is continuous with the cerebral
cortex, along the inner side of the olfactory sulcus, and also with the small trans-
verse convolution which closes in that sulcus posteriorly. The inferior surface of
the tract, including the internal and external angles, is covered by white matter,
the component fibres of which run in a sagittal direction. The roots of the
olfactory tract are the direct continuations of this white matter. Three roots are
usually described, an external and an internal white root, and a middle or grey root.
The external root is the largest and most important of these. It passes along the
outer boundary of the anterior perforated space to the temporal lobe, and ends in
the amygdaloid nucleus and the adjacent part of the cortex. The middle root
passes backwards and upwards under cover of the tuber olfactorium, a greyish

OLFACTORY NERVES
789
elevation which is placed in the front part of the anterior perforated space; from
thence it passes into the anterior commissure. The internal root passes backwards
and inwards, and then bends upwards to end in the anterior extremity of the gyrus
fornicatus.
According to Obersteiner, no white mesial root, as commonly described, is to be seen;
nor does a middle grey root, in the common meaning of the term, exist.'
The following is an outline of the cerebral part of the course of the olfactory
fibres. On entering the olfactory bulb, they suffer an interruption in the nerve-
cells of that body, these cells apparently corresponding to the nucleus of origin
of an ordinary cranial nerve. From thence the fibres enter the white matter of the
olfactory tract and may be here classified into two groups, namely:-(a) Fibres
which enter the cortex of the tract; and (b) fibres which pass through the white
FIG. 442.-NERVES OF THE NASAL CAVITY.

FRONTAL SINUS
NASAL
NERVE
OLFACTORY
NERVE
OLFACTORY
NERVE TO SUPE
RIOR TURBINATE
BONE
SPHENOIDAL SINUS
VIDIAN NERVE
MECKEL'S
GANGLION
DESCENDING
PALATINE
ORIFICE OF EUSTACHIAN
TUBE
NASAL BRANCHES
POSTERIOR
PALATINE
ANTERIOR
PALATINE
MIDDLE
PALATINE
matter to other parts of the brain without becoming connected to the cortex of the
tract. (a) From the cortex of the tract some fibres pass via the external white
root to the cortex of the temporal lobe. Others enter the anterior commissure, and
proceed to the cerebral cortex of the opposite side. (b) Of the fibres which pass
directly through the tract, some pass by the external white root to the temporal
lobe; others pass as a slender tract into the under border of the internal capsule,
and so reach the front of the optic thalamus (Obersteiner). A commissural bundle
of fibres, which passes from one olfactory tract to its fellow of the opposite side,
via the anterior commissure, is also described.
In its peripheral distribution, the olfactory nerve does not extend
beyond the limits of the mucous membrane which invests the ethmoid bone.
The olfactory filaments are composed exclusively of non-medullated fibres,
and to this their pearly grey colour is due. As they pass through the foramina in
the cribriform plate, they are invested by sheaths derived from the dura mater.

790
THE NERVOUS SYSTEM
They are divided into two groups, an outer and an inner. Both groups ramify
between the periosteum and the deep surface of the mucous membrane. The outer
group, twelve to twenty in number (Valentin), enter the nose through the outer
series of foramina in the cribriform plate, and form a richly-meshed plexus on the
upper surfaces of the superior and middle turbinated bones. The inner group,
twelve to sixteen in number (Valentin), pass through the inner series of foramina
close to the crista galli, and on entering the nose are lodged at first in grooves on
the perpendicular plate of the ethmoid bone. They communicate with one another,
forming a plexus, and finally break up into spreading tufts of extremely fine
filaments.
SECOND OR OPTIC NERVES
The optic nerves appear at the base of the brain as a pair of round white
cords, which arise from the optic chiasma. From the posterior aspect of the
latter structure, two somewhat similar cords, the optic tracts, pass backwards and
outwards. Each optic nerve is continuous, through the chiasma, with both optic
tracts. It will be convenient to trace first the central connections of the optic
nerves through the optic tracts, and afterwards to follow the nerves forwards from
the optic chiasma to the eyeball.
The optic chiasma or commissure rests upon the optic groove, on the superior
surface of the sphenoid bone. It is in relation above with the third ventricle,
being separated only by a thin layer of grey matter from that cavity. The internal
carotid arteries are close to its outer sides.
Constitution of the optic chiasma. -Four sets of fibres have been described in
the optic chiasma, namely: (a) Fibres from one optic tract to the optic nerve of the
same side; (b) fibres from one optic tract to the optic nerve of the opposite side;
(c) commissural fibres passing from one optic tract to its fellow of the opposite
side; and (d) fibres from one optic nerve to the nerve of the opposite side. The
existence of the first three sets is well ascertained. The fourth set is now very
generally believed to have been erroneously described. (a) The uncrossed fibres
proceed from the lateral or temporal half of the retina of the same side. They
occupy the outer part of the chiasma. (b) The crossed fibres, which form the
largest constituent of the chiasma, are derived from the mesial or nasal half of
the retina, and pass into the optic tract of the opposite side. (c) The commissural
fibres occupy the back part of the chiasma. They have nothing to do with vision.
Two sets are described under the names of Gudden's and Meynert's commissures.
The optic tract passes backwards and outwards along the outer side of the
tuber cinereum, and then passes under cover of the temporal lobe, winding around
the crus cerebri. As it applies itself to the latter, it adheres to it, and becomes
flattened from above downwards. It next inclines upwards, and divides into an
external and an internal root. These roots proceed towards the external and
internal geniculate bodies, respectively. The internal root contains the fibres of
Gudden's commissure.
A portion of the external root becomes connected with the nerve-cells in the
external geniculate body; another part enters the pulvinar of the optic thalamus,
while a third part passes in the superior brachium to the superior quadrigeminal
body of the same side.
The fibres of the optic nerve are therefore interrupted in the ganglion cells of
the external geniculate body, the pulvinar of the optic thalamus, and the superior
quadrigeminal body; hence, these three bodies are said to contain the nuclei of
origin of the optic nerve. Other fibres, however, collectively termed the optic
radiation, pass out of these three bodies, and pass through the most posterior part
of the inner capsule to the occipital lobe, and thus the cortical origin of the optic
OPTIC NERVES
791
nerve is established. The exact area of the cortex devoted to the sense of sight is
still a matter of dispute, but the weight of evidence seems to be in favour of the
cuneus being the cerebral centre of vision.
Other roots of the optic nerve are described, of which the direct cortical root
(Wernicke and Gudden) is perhaps the most important. This root leaves the optic
tract as the latter is crossing the crus cerebri, and runs upwards in the inner
capsule to join the optic radiation. Another root is described which passes from
the optic chiasma into the central grey matter of the third ventricle. The
descending root (Stilling) enters the crus and is variously distributed; a portion of
its fibres become connected with the oculo-motor nucleus, and thus a path for
reflex movements of the iris and ciliary muscle is probably established.
Gudden's commissure.-Fibres emerge from the posterior quadrigeminal body,
constituting its brachium, and enter the internal geniculate body. After partial
interruption in the nerve-cells of the latter, these fibres are continued into the
optic tract and pass across to the opposite side, forming the back part of the optic
chiasma, to enter into a similar relation to the internal geniculate and posterior
quadrigeminal bodies of the opposite side.
Meynert's commissure.-From the grey matter of the tuber cinereum fibres
arise which cross the middle line behind Gudden's commissure and enter the crusta
on the opposite side, from whence they are said to pass into the subthalamic body.
The optic nerve passes forwards and outwards from the chiasma and enters
the orbit through the optic foramen, accompanied by the ophthalmic artery, the
vessel being external to and slightly below the nerve. It then slightly changes its
direction and passes almost directly forwards to enter the back of the eyeball about
three millimetres internal to and slightly below the posterior extremity of the optic
axis; having gained the interior of the eyeball its fibres spread out in the retina. In
its course through the orbit it is surrounded by the ciliary arteries and nerves;
its upper surface is crossed obliquely by the ophthalmic artery, and the lenticular
ganglion is in contact with its outer surface. Near the optic foramen it is sur-
rounded by, and in close relation to, the four recti muscles; but further forwards
it is separated from the muscles by an interval containing fat. The arteria
centralis retina pierces the under surface of the optic nerve near the middle point
of the intraorbital part of its course and runs from thence into the eyeball in the
axis of the nerve. Very distinct prolongations of the cerebral membranes accom-
pany the optic nerve. The dura mater, having entered the orbit through the optic
foramen, delaminates into the orbital periosteum and the sheath of the optic nerve;
the latter is tough and strong, and becomes continuous with the sclerotic of the
eyeball. Within the dura mater is a narrow subdural space, then the arachnoid
and a comparatively wide subarachnoid space, the inner boundary of which is
formed by the pia mater, which invests the bundles of nerve-fibres.


THIRD OR OCULO-MOTOR NERVES
The third or oculo-motor nerve arises from a column of nerve-cells which is
placed in the grey matter beneath the floor of the aqueduct of Sylvius immediately
dorsal to the posterior longitudinal bundle. This nucleus extends from the level
of the posterior commissure to a point corresponding to the interval between the
nates and testes, where it is imperfectly separated from the nucleus of the fourth
The fibres arising from this nucleus pass downwards and forwards in a
series of fasciculi, which traverse the posterior longitudinal bundle, the red nucleus,
and the inner part of the substantia nigra. The fibres emerge (superficial origin) in a
row of about nine fasciculi from the oculo-motor groove at the inner side of the crus.
The third nerve passes between the superior cerebellar and posterior cerebral

nerve.
792
THE NERVOUS SYSTEM
arteries, and then pierces the dura mater about midway between the anterior and
posterior clinoid processes of the sphenoid bone in the centre of a little triangular
space which has the following boundaries: externally, the free margin of the
tentorium cerebelli, posteriorly the attached margin of the tentorium, and internally
a ridge of dura mater which extends from the posterior to the anterior clinoid
process. It then enters the outer wall of the cavernous sinus and runs forwards
to the sphenoidal fissure, occupying a position superior and internal to the fourth
FIG. 443.-DEEP ORIGIN OF THE THIRD NERVE. (After Krause.)

CRUSTA
AQUEDUCT OF SYLVIUS
-DESCENDING
ROOT OF
TRIGEMINAL
NERVE
NUCLEUS OF
THIRD NERVE
POSTERIOR
LONGITUDINAL
BUNDLE
SUBSTANTIA
NIGRA
RAPHE
THIRD NERVE
nerve. At the sphenoidal fissure it divides into a superior and an inferior division.
These divisions, as they enter the orbit through the sphenoidal fissure, pass between
the two heads of the external rectus muscle, and are separated from one another
by the nasal branch of the ophthalmic division of the fifth nerve.
The superior division supplies the superior rectus. It enters that muscle on
its ocular surface and sends a branch through it to supply the levator palpebræ
superioris.
The inferior division, considerably larger than the superior, divides into three
branches; two of these, the nerves to the internal and inferior rectus muscles,
TROCHLEAR NERVES
793
pierce the ocular surfaces of the muscles which they supply. The third branch,
the nerve to the inferior oblique, is considerably longer than the other two. It
runs forwards in the interval between the inferior and external rectus muscles, and
pierces the posterior border of the inferior oblique. Near its commencement it
gives off the short or motor root to the lenticular ganglion.o
The third nerve supplies all the orbital muscles, with the exception of the
external rectus and the superior oblique. It also supplies (through the lenticular
ganglion) the ciliary muscle and the circular fibres of the iris (sphincter iridis).
FOURTH OR TROCHLEAR NERVES
The fourth or trochlear nerve arises from a column of nerve-cells which is
continuous with the nucleus of the third nerve. This column of cells is embedded
in the central grey matter below the aqueduct, and extends from the level of the
interval between the nates and testes to the lower margin of the latter bodies.
FIG. 444.-SECTIONS THROUGH THE ORIGIN OF THE FOURTH NERVE. (Stilling.)
(The upper figure is an oblique section, the lower is a coronal section.)

IV
AQUEDUCT OF SYLVIUS-
NUCLEUS OF FOURTH
NERVE
POSTERIOR LONGI-
TUDINAL BUNDLE
RAPHE
IVO
IV
IV
IV
V
IV
-AQUEDUCT OF SYLVIUS
SUPERIOR CEREBELLAR
FILLET
PEDUNCLE
The nerve-fibres issuing from this elongated nucleus form two or three rounded
bundles, which run downwards, backwards, and slightly outwards along the outer
side of the nucleus, and then incline inwards to reach the valve of Vieussens, in
the substance of which they decussate with their fellows of the opposite side and
become collected into a single bundle (fig. 444). This bundle emerges as a slender
rounded fasciculus (superficial origin) from the valve of Vieussens, close to the
frenulum veli, immediately below the testes, and winds round the crus cerebri to
appear at the base of the brain near the anterior margin of the pons. The right
nerve, therefore, arises from the left nucleus and vice versa.
The fourth nerve pierces the dura mater at a point a little behind and external
to the posterior clinoid process of the sphenoid bone in the postero-external angle
of the triangular space which has been described in connection with the third
It runs forwards in the outer wall of the cavernous sinus, being placed
between the third nerve which is above and internal to it, and the ophthalmic
division of the fifth nerve, which is situated below and to its outer side. As it

nerve.

794
THE NERVOUS SYSTEM
approaches the sphenoidal fissure it bends upwards, crosses on the outer side of
the third nerve, and passes through the innermost part of the sphenoidal fissure.
As it passes through the fissure it is placed above and internal to the frontal nerve.
It then passes inwards above the origin of the levator palpebræ superioris muscle,
and pierces the orbital surface of the superior oblique muscle, in which it ends.
The fourth nerve is the smallest of the cranial nerves. It is remarkable for the
length of its intracranial course and for its mode of decussation.
FIFTH OR TRIGEMINAL NERVE
The fifth or trigeminal nerve consists of two parts, a large sensory root (portio
major) and a small motor root (portio minor). The portio major passes into a
ganglion (Gasserian ganglion) which has been compared to the ganglion on the
posterior root of a spinal nerve, which it probably resembles in exercising a trophic
influence on the nerve fibres, though this has not been experimentally proved.
The superficial origin' of the nerve is from the side of the pons near its upper
border. The deep origin of the portio major is chiefly by the ascending root, a
long tract of fibres which runs for a considerable distance within the cerebro-spinal
axis. The portio major has, however, in addition to this, several supplementary
origins. The portio minor arises principally from a nucleus which is embedded
in the grey matter of the floor of the fourth ventricle, but it also receives the
whole or the greater part of a long tract of fibres, which passes downwards from the
mesencephalon, and which is termed the descending root.
The ascending root commences in the upper part of the spinal cord at the level
of the second cervical nerve, and passes upwards, increasing in size as it ascends.
It is placed on the outer side of the substantia gelatinosa, in which some of its
fibres appear to take origin. In transverse sections through the lower part of the
medulla it appears as a crescentic white bundle of fibres, convex outwards, placed
on the outer side of the substantia gelatinosa, and covered only by some white
matter belonging to the direct cerebellar tract (fig. 432). Higher up it is more
deeply placed, being covered by the restiform body and by the roots of the
auditory nerve. In the grey matter of the upper third of the fourth ventricle it
comes in contact with a cluster of nerve cells which is termed the accessory sensory
nucleus; here it takes a bend downwards and forwards, partly intersecting the
accessory nucleus, receives accessions of fibres from that nucleus, and, according to
most observers, also from the cerebellum and from the substantia ferruginea of
the opposite side. It now passes downwards and forwards somewhat obliquely
through the pons, and emerges (superficial origin) as the portio major of the fifth
nerve at the side of the pons near the superior border. The accessory nucleus is a
mass of cells of an elongated ovoid form embedded in the grey matter of the floor
of the fourth ventricle at a level a little above the striæ acusticæ. The cerebellar
root passes downwards and forwards from the cerebellum around the outer side of
the superior cerebellar peduncle of its own side, and joins the outermost portion
of the sensory root.
The descending root arises from a column of nerve-cells which is embedded in
the grey matter of the aqueduct above and external to the nucleus of the third
nerve. The root commences at the level of the upper part of the nates, and
increases in size as it descends, forming a white bundle of fibres crescentic in
section, some of these fibres being connected with the nerve-cells which are placed
on their inner side (fig. 444, v). It passes through the grey matter of the upper part
of the floor of the fourth ventricle, close to the outer side of the substantia ferru-
ginea, and reaches the upper part of the motor nucleus of the fifth nerve. Here it
is joined by the principal part of the motor root, which arises from the motor
OPHTHALMIC DIVISION OF THE FIFTH NERVE
795
nucleus, and by a few fibres from the motor nucleus of the opposite side. It then
passes downwards and forwards through the pons to emerge as the portio minor
of the fifth nerve. At its emergence it is placed a little in front of the sensory
portion, and is separated from the latter by some of the transverse fibres of the
pons.
The motor nucleus is an ovoid mass of cells considerably shorter than
the accessory sensory nucleus, on the inner side of which it is placed. It is on
the same line as the nucleus of the facial nerve, and is immediately in front of
that nucleus.
According to some observers some fibres of the descending root enter the sensory root
and are said to eventually pass into the ophthalmic division.
The sensory and motor roots of the nerve pass downwards and forwards towards
an aperture in the dura mater which is placed under cover of the tentorium
cerebelli, a little external to the apex of the petrous portion of the temporal bone.
In this course the motor root takes a half-spiral turn around the sensory root,
passing first to the inner side, and then below the latter. Both roots then pass
through the aperture above mentioned to enter Meckel's space, between the sup-
porting and periosteal layers of the dura mater. The motor root passes out of the
skull through the foramen ovale, accompanied by a larger sensory bundle from
the Gasserian ganglion, and joins with the latter outside the skull to form the
mandibular (or inferior maxillary) division of the fifth nerve. The sensory root
spreads out into a flattened, somewhat fan-shaped, plexiform bundle, and enters
the Gasserian ganglion.
The Gasserian ganglion is a reddish-grey band of ganglionic matter, with its
long axis slightly curved so as to present a convexity forwards and outwards. The
upper and lower surfaces of the ganglion are also slightly convex and are some-
what adherent to the dura mater, the upper surface being more firmly attached
than the lower. It rests on a depression on the petrous bone and, in front of this,
on the cartilage which occupies the foramen lacerum medium. From the convex
antero-external border of the ganglion, three large bundles of nerve-fibres arise.
The first or ophthalmic division enters the orbit through the sphenoidal fissure.
The second or maxillary (superior maxillary) division leaves the skull through the
foramen rotundum. The third division passes through the foramen ovale in front
of the motor root of the fifth nerve, with which it unites, as already described,
to form the mandibular (inferior maxillary) division. The Gasserian ganglion
receives communications from the carotid plexus of the sympathetic, and is said to
furnish some minute twigs to the dura mater.



FIRST OR OPHTHALMIC DIVISION OF THE FIFTH NERVE
The ophthalmic is the smallest of the three divisions of the fifth, and is entirely
sensory in function. It passes forwards and inwards in the outer wall of the
cavernous sinus, where it is placed below and external to the fourth nerve. Imme-
diately behind the sphenoidal fissure it divides into three branches. These branches
pass through the sphenoidal fissure, where they pierce the fibrous derivative of the
dura mater which closes in the fissure. Two of them, the frontal and the lachrymal,
enter the orbit above the external rectus muscle. The remaining branch, the nasal,
passes between the two heads of that muscle. In its course in the outer wall
of the cavernous sinus the ophthalmic division receives communications from the
carotid plexus of the sympathetic, and gives off a tentorial branch (nervus recurrens
rami primi, Luschka) which runs backwards for a short distance within the sheath
of the fourth nerve, and is distributed between the layers of the tentorium cerebelli.
It also gives communicating branches to the third, fourth, and sixth nerves.
orbital muscles receive their sensory supply through these communications.
The

796
THE NERVOUS SYSTEM
(1) The frontal nerve is the largest branch of the ophthalmic division. It
passes forwards and upwards on the inner side of the third nerve, and enters the
orbit immediately external to, and a little below, the fourth nerve. It passes
forwards between the periosteum of the orbit and the levator palpebræ superioris
muscle, and, a little behind the middle of the orbit, divides into two branches,
termed the supraorbital and supratrochlear.
(2) The supraorbital nerve leaves the orbit by passing through the supraorbital
notch or foramen, where it gives twigs to the upper eyelid, and turns upwards on
the frontal bone, accompanied by the supraorbital artery. It divides into two
branches, an external and an internal. Both these branches divide into several
twigs, which pass very obliquely through the anterior belly of the occipito-frontalis
muscle, and supply the integument of the forehead and fore part of the scalp. The
external branch, which is considerably larger than the internal, may be traced
backwards nearly as far as the lambdoidal suture.
(3) The supratrochlear nerve is directed forwards and inwards above the pulley
of the superior oblique muscle. It communicates with the infratrochlear branch
of the nasal nerve and turns upwards on the forehead, accompanied by the frontal
FIG. 445.-NERVES OF THE ORBIT, FROM THE OUTER SIDE.
(From Sappey, after Hirschfeld and Leveillé.)
LENTICULAR GANGLION
SUPERIOR DIVISION OF THE THIRD NERVE
SUPRAORBITAL
NERVE
SHORT CILIARY.
NERVES
BRANCH OF THIRD TO
INFERIOR OBLIQUE
NASAL BRANCH OF OPHTHALMIC
LONG ROOT OF LENTICULAR
GANGLION
OPTIC NERVE
THIRD NERVE
SIXTH NERVE
GASSERIAN GANGLION
OPHTHALMIC DIVISION
OF FIFTH NERVE
SHORT ROOT OF
LENTICULAR GANGLION
SYMPATHETIC ROOT OF LENTICULAR
GANGLION
artery. It is much smaller than the supraorbital nerve, and it is distributed to a
small area of integument around the glabella. It gives twigs to the inner part of
the upper eyelid.
(4) The lachrymal nerve is the smallest of the three branches of the ophthalmic
division. It passes through the sphenoidal fissure external to and slightly below
the frontal nerve, and is directed forwards and outwards along the upper border
of the external rectus muscle to the lachrymal gland. Immediately behind the
lachrymal gland it communicates with the temporal branch of the orbital nerve,
forming a loop convex forwards; from this loop and from the adjacent part of the
trunk of the nerve a number of twigs pass into the gland substance. A small twig
passes beyond the gland and is distributed to the integument and conjunctiva at
the outer canthus of the eye.
(5) The nasal nerve enters the orbit by passing forwards between the superior
and inferior divisions of the third nerve, and takes an oblique course forwards and
inwards to reach the inner wall of the orbit. In this course it passes between the
optic nerve and the superior rectus muscle. It then passes through the anterior
internal orbital canal, accompanied by the anterior ethmoidal vessels, crosses the
cribriform plate of the ethmoid bone under cover of the dura mater, and enters
MAXILLARY DIVISION OF THE FIFTH NERVE
797
the nasal fossa through a slit-like aperture at the side of the crista galli (the
ethmoidal fissure). It terminates within the nasal fossa by dividing into three
branches: an internal, or septal; an external; and an anterior, or terminal.
Branches.-The long root to the lenticular ganglion is given off at the sphe-
noidal fissure. It is a slender filament which passes forwards to join the upper
and back part of the ganglion. The long ciliary nerves, usually two in number,
arise from the nasal trunk as the latter is crossing the optic nerve. They are
directed forwards along the inner side of the optic nerve, and join the short ciliary
nerves after they pierce the sclerotic (page 887). The infratrochlear nerve is given
off by the nasal just before the latter enters the anterior internal orbital canal. It
passes forwards beneath the pulley of the superior oblique muscle, and supplies the
skin and conjunctiva around the inner canthus of the eyes and the integument of
the upper part of the nose. It also supplies the lachrymal sac and caruncle. It
communicates with the supratrochlear nerve in front of (sometimes behind) the
pulley.
The internal or septal branch of the nasal nerve runs downwards and forwards
on the upper and front part of the nasal septum.
The external branch gives two or three twigs to the anterior extremities of the
superior and middle turbinated bones, and to the mucous membrane of the outer
wall of the nose.
The terminal or anterior branch runs downwards in a groove on the inner
surface of the nasal bone. It pierces the wall of the nose between the nasal bone
and the lateral cartilage, and supplies the integument of the lower part of the side
of the nose as far as the tip of that organ.

LENTICULAR GANGLION
The lenticular, ciliary, or ophthalmic ganglion is a small reddish-grey body
about the size of a pin's head. It is quadrilateral in outline, and its outer and
inner surfaces are slightly convex. It is placed between the optic nerve and the
external rectus muscle, about a quarter of an inch in front of the sphenoidal
fissure. Following the general rule applying to the sporadic ganglia which are
connected with the fifth nerve, it is provided with three roots, a motor, a sensory,
and a sympathetic. The motor or short root is derived from the branch of the
oculo-motor to the inferior oblique muscle; it enters the posterior inferior angle of
the ganglion. The sensory or long root is a branch of the nasal nerve; it passes
along the outer side of the optic nerve, and enters the upper and back part of the
ganglion. The sympathetic root is derived from the cavernous plexus of the
sympathetic; it may enter the back part of the ganglion in the form of fine twigs,
but usually reaches the ganglion for the most part through the third and nasal
nerves, being incorporated with the motor and sensory roots.
From the anterior border of the ganglion about six short ciliary nerves arise;
these subdivide and communicate with the long ciliary nerves, forming about twenty
nerves which separate into a supero-external and an infero-internal group, and
surround the optic nerve. The nerves pierce the sclerotic in a circle around the
entrance of the optic nerve into the eyeball, and pass forwards between the sclerotic
and choroid coats of the eye. They supply nerves of ordinary sensation and trophic
nerves to the eyeball (derived from the nasal); the radiating fibres of the iris
(derived from the sympathetic); and the ciliary muscle and sphincter of the pupil
(derived from the oculo-motor) (page 886).

SECOND OR MAXILLARY DIVISION OF THE FIFTH NERVE
The maxillary (superior maxillary) division of the fifth nerve is intermediate
in size between the mandibular (inferior maxillary) and ophthalmic divisions, and,

798
THE NERVOUS SYSTEM
like the latter, it is entirely sensory in function. It proceeds forwards from the
Gasserian ganglion for about one-third of an inch within the skull, and then passes
through the foramen rotundum. It traverses the upper part of the spheno-maxillary
fossa, and, inclining upwards, passes into the orbit through the spheno-maxillary
fissure. It then courses forwards along the infraorbital groove, accompanied by
the infraorbital artery, to the infraorbital canal, and passes through the canal to
emerge at the infraorbital foramen, where it terminates, almost immediately, in
three sets of branches, which proceed to the upper lip, the nose, and the lower
eyelid.
Branches.-The branches of the maxillary division may be classified into four
sets, namely:-(1) Intracranial branches; (2) branches which are given off in the
spheno-maxillary fossa; (3) branches which arise from the portion of the nerve
which is placed in the infraorbital canal; and (4) terminal branches.
FIG. 446.-THE MAXILLARY NERVE SEEN FROM WITHOUT. (Beaunis.)
ANTERIOR DENTAL
MAXILLARY NERVE
ORBITAL BRANCH
MAXILLARY NERVE
MECKEL'S GANGLION
POSTERIOR DENTAL
X
LOOP FORMED BY MIDDLE AND ANTERIOR DENTAL NERVES
The first set (1) consists of one or two recurrent twigs to the dura mater,
which form loops with the recurrent branch of the mandibular (inferior maxillary)
division. The second set (2) comprises the orbital nerve, the spheno-palatine
nerves, and the posterior superior dental nerves. (3) The middle and anterior
superior dental nerves constitute the third set. (4) The terminal branches fall into
three groups, which are termed labial, nasal, and palpebral branches.
The orbital or temporo-malar nerve passes upwards and forwards through the
spheno-maxillary fissure by which it enters the orbit, and terminates by dividing
into two branches, temporal and malar. The temporal branch communicates
with the lachrymal nerve, and then runs forwards through the periosteum on
the outer wall of the orbit, and traverses the spheno-malar foramen. It enters
the temporal fossa and pierces the deeper of the two lamella of the temporal
fascia. It runs outwards for about a quarter of an inch in the fat between the two
lamellæ of the fascia, and pierces the superficial lamella about an inch above the
superior border of the zygoma; here it forms a well-marked communication with
the temporal branch of the facial nerve, and then ramifies in the integument of

MAXILLARY DIVISION OF THE FIFTH NERVE
799
the anterior temporal region. The malar branch (ramus subcutaneus malæ) runs
forwards in the loose fatty tissue of the orbit, and passes through the malar foramen.
It pierces the orbicularis palpebrarum and supplies a small area of skin over the
prominence of the cheek. It communicates with the malar branch of the facial
nerve.
The spheno-palatine nerves are two stout twigs which pass downwards to
Meckel's ganglion, of which they form the sensory roots; most of the nerve-
fibres pass on the inner side of the ganglion without traversing the ganglionic
substance, but it is more convenient to trace these nerves with the branches of the
ganglion.
The posterior superior dental nerves, usually two in number, pass downwards
and outwards through the pterygo-maxillary fissure. They furnish several twigs
to the gums (nervuli gingivales) and adjacent part of the mucous membrane of
the cheek. They then enter foramina in the maxilla, follow the curve of the
alveolar arch through minute canals in the bone above the roots of the molar teeth,
and end by communicating in a plexiform manner with the middle dental nerve.
They give off minute branches to the mucous membrane of the antrum, and furnish
three twigs to each of the molar teeth. These twigs enter the foramina at the tips
of the fangs of the teeth and ramify in the pulp.
The middle and anterior superior dental nerves are small branches which pass
through canals in the substance of the maxilla to supply the incisor, canine, and
bicuspid teeth and the corresponding regions of the gums. In the upper, and
more particularly in the lower, parts of these canals the nerves are surrounded on all
sides by thick bone; but in the middle part, where they are traversing the anterior
wall of the antrum, they are surrounded by a mere shell of bone, which is not
infrequently deficient on the deep surface, so that the nerves may lie in grooves in
the anterior wall of the antrum between the bone and mucous membrane. In this
situation the nerves furnish twigs to the antrum. The middle dental nerve enters
a foramen at the posterior part of the infraorbital canal. It supplies the bicuspid
teeth, and communicates with the anterior and posterior dental nerves. It may
be wanting. The anterior dental nerve enters a canal close to the infraorbital
foramen, and supplies the incisor and canine teeth. It gives off a nasal branch,
which passes through a minute canal in the bone and enters the anterior part
of the inferior meatus. Here it ramifies in the mucous membrane, and com-
municates with the naso-palatine nerve from Meckel's ganglion. It communicates
with the middle dental nerve.
Two small gangliform enlargements are occasionally found on the plexiform arch formed
by the dental nerves.
One of these, the ganglion of Valentin, is situated above the root of
the second bicuspid at the junction of the middle and posterior dental nerves. The other,
the ganglion of Bochdalek, is placed on the junction of the anterior and middle dental


nerves.
The labial branches, usually four in number, are the largest of the three
terminal divisions of the maxillary nerve. They pass downwards, spreading out as
they descend, under cover of the levator labii superioris muscle, and ramify in the
structures forming the upper lip, very large twigs being supplied to the mucous
membrane.
The nasal branches, three or four in number, are intermediate in size. They
pass inwards under cover of the levator labii superioris alæque nasi, and supply the
integument on the lateral aspect of the nose.
The palpebral branches, the smallest of the terminal divisions of the nerve,
pierce the origin of the levator labii superioris, and turn upwards around the
lower border of the orbicularis palpebrarum. They are usually two in number, an
external and an internal; they ramify in the integument of the lower eyelid.

800
THE NERVOUS SYSTEM
The terminal branches of the maxillary division communicate freely with the
infraorbital branch of the facial, forming the infraorbital plexus. The plexus is
placed under cover of the levator labii superioris.
-
MECKEL'S GANGLION
The spheno-palatine, nasal, or Meckel's ganglion is a small reddish-grey body
which is situated in the spheno-maxillary fossa. It is triangular in form, flattened
at the sides, and measures about one-fifth of an inch in its longest diameter. It is
provided with three roots, a motor and a sympathetic, which reach it through the
Vidian nerve, and a sensory root from the maxillary nerve. The latter root is in
the form of two stout twigs, which are described as the spheno-palatine nerves.
Roots. The great superficial petrosal nerve is the motor root of the ganglion.
It arises from the geniculate ganglion of the facial nerve within the aqueduct of
Fallopius, and enters the cranial cavity by traversing the hiatus Fallopii. It then
runs forwards and inwards in a groove in the petrous portion of the temporal
bone, and, after passing under the Gasserian ganglion, enters an oblique canal in
the cartilage which occupies the foramen lacerum medium. Having reached the
posterior opening of the Vidian canal, it unites with the great deep petrosal nerve
to form the Vidian nerve.
The great deep petrosal nerve is of a grey colour and is soft in consistence. It
arises from the carotid plexus of the sympathetic close to the intracranial termina-
tion of the carotid canal, traverses a canal in the cartilage, which occupies the
foramen lacerum medium, and joins the Vidian nerve.
The Vidian nerve runs forwards through the canal of the same name, accom-
panied by the Vidian artery, and enters the spheno-maxillary fossa, where it ends
in the posterior angle of Meckel's ganglion. The majority of the facial fibres in
the Vidian probably pass through the ganglion into the posterior palatine nerve to
supply the levator palati and azygos uvulæ muscles. While within the canal the
Vidian nerve furnishes nasal twigs to the mucous membrane of the posterior part
of the superior meatus of the nose. They may be regarded as superior nasal nerves,
which, after leaving Meckel's ganglion, have become associated with the Vidian
nerve for a part of their course.
Branches. The branches of Meckel's ganglion are classified into (1) ascending,
to the orbit; (2) internal, to the mucous membrane of the nose; (3) descending,
to the hard and soft palate; and (4) posterior, to the pharynx.
(1) Ascending branches.-The ascending or orbital branches are two or three
small twigs which enter the orbit through the spheno-maxillary fissure, and pro-
ceed within the periosteum to the inner wall of the orbit, where they pass through
the posterior internal orbital canal and through the foramina in the suture behind
that canal to be distributed to the mucous membrane which lines the posterior
ethmoidal cells and the sphenoidal sinus.
(2) Internal branches.-The internal branches are derived in part from the
inner side of the ganglion, but are also largely made up of fibres which pass from
the spheno-palatine nerves without traversing the ganglionic substance. They are
disposed in two sets, the superior nasal and the septal.
The superior nasal are six or seven small twigs which pass through the spheno-
palatine foramen, and are distributed to the mucous membrane covering the
posterior parts of the superior and middle turbinated bones. They also furnish
twigs to the lining membrane of the posterior ethmoidal cells.
The septal branches are two or three in number, and pass inwards through the
spheno-palatine foramen. They cross the roof of the nasal fossa to reach the back
part of the nasal septum, where the smaller twigs terminate. The largest nerve of
the set, naso-palatine nerve, or nerve of Cotunnius, runs downwards and forwards


MANDIBULAR DIVISION OF THE FIFTH NERVE
801
in a groove in the vomer between the periosteum and the mucous membrane to the
anterior palatine canal. Here it communicates with the nasal branch of the
anterior superior dental nerve. The two naso-palatine nerves then pass through
the foramina of Scarpa in the anterior palatine canal, the left nerve passing through
the anterior of the two foramina. In the lower part of the anterior palatine canal
the two nerves form a plexiform communication (formerly described as Cloquet's
ganglion) and furnish twigs to the anterior part of the hard palate. In this situa-
tion they communicate with the anterior palatine nerves.
(3) Descending branches.-The descending branches are the great or anterior,
the posterior, and the external palatine nerves. Like the internal set of branches,
they are in part derived from the ganglion and in part directly continuous with
the spheno-palatine nerves.
The great or anterior palatine nerve arises from the inferior angle of Meckel's
ganglion, and passes downwards through the posterior palatine canal, accompanied
by the descending palatine artery. Emerging from the canal, it divides into two
or three branches, which pass forwards in grooves in the hard palate and supply
the glands and mucous membrane of the hard palate and the gums on the inner
aspect of the alveolar border of the upper jaw. During its course through the
posterior palatine canal, the anterior palatine nerve gives off, usually two, inferior
nasal nerves. These nerves pass through small openings in the perpendicular
plate of the palate bone to supply the mucous membrane lining the back parts of
the inferior turbinated bone, and of the middle and inferior meatus of the nose.
The posterior or small palatine nerve passes downwards through the accessory
palatine canal, and enters the soft palate, where it supplies the levator palati and
azygos uvulæ muscles. According to the researches of Horsley and Beevor the
eleventh nerve supplies the levator palati; they state that the path by which the
fibres from this nerve reach the palate is probably through the upper branch of
the pharyngeal plexus.
The external palatine nerve, the smallest of the three, traverses the external
palatine canal, and supplies twigs to the tonsil and to the adjacent part of the soft
palate.
(4) Posterior branch.-The Vidian is considered by some anatomists to be a
branch, in which case it would be classed here. We have, however, regarded it
as the united motor and sympathetic root of the ganglion; therefore, the pharyngeal
branch only remains to be described.
The pharyngeal branch is of small size, and passes backwards and somewhat
inwards through the pterygo-palatine canal, accompanied by the pterygo-palatine
artery. It is distributed to the mucous membrane of the uppermost part of the
pharynx, to the upper part of the posterior nares, to the opening of the Eustachian
tube, and to the lining of the sphenoidal sinus.

THIRD OR MANDIBULAR DIVISION OF THE FIFTH NERVE
The mandibular (inferior maxillary) division is the largest of the three divisions
of the fifth nerve, and is formed, as before stated, by the union of two distinct parts,
namely, the entire motor root of the fifth nerve and a large bundle of fibres
derived from the sensory root and traversing the Gasserian ganglion. These two
parts pass through the foramen ovale and unite immediately outside the skull to form
a large trunk which terminates almost directly after its formation by dividing into
a smaller anterior and a larger posterior portion. The anterior portion is chiefly
motor, and the posterior division mainly sensory in function. Previous to its
division, two branches arise from the trunk of the nerve, namely, the recurrent
nerve and the nerve to the internal pterygoid.
(1) The recurrent nerve enters the cranium through the foramen spinosum,
3 F

802
THE NERVOUS SYSTEM
accompanying the middle meningeal artery, and divides into an anterior and a
posterior branch. The anterior branch communicates with the meningeal branch
of the maxillary division of the fifth nerve, furnishes filaments to the dura mater,
and ends in the osseous substance of the great wing of the sphenoid. The posterior
branch traverses the petro-squamous suture and ends in the lining membrane of
the mastoid cells.
(2) The nerve to the internal pterygoid passes under cover of a dense layer of
fascia derived from an expansion of the ligamentum pterygo-spinosum, and enters
the deep surface of the muscle. Near its commencement this nerve furnishes a
motor root to the otic ganglion.
The ANTERIOR PORTION of the mandibular division of the fifth nerve supplies the
temporal, masseter, and external pterygoid muscles, and gives off a sensory branch,
FIG. 447.-DISTRIBUTION OF THE MANDIBULAR DIVISION OF THE TRIGEMINAL
NERVE. (Henle.)
LONG BUCCAL
NERVE
SUB-
MANDIBULAR
GANGLION
MENTAL
BRANCH
ANTERIOR
TEMPORAL
NERVE
AURICULO-
TEMPORAL
NERVE
POSTERIOR
TEMPORAL
NERVE
NERVE TO
MASSETER
CHORDA
TYMPANI
MYLO-HYOID
NERVE
LINGUAL
NERVE
MANDIBULAR
OR INFERIOR
DENTAL
NERVE
the long buccal nerve; the latter is accompanied, in the first part of its course, by a
small strand of motor fibres which leaves it to end in the anterior part of the
temporal muscle.
(1) The temporal nerves, usually two in number, pass between the bone and
the upper border of the external pterygoid muscle, and turn upwards around
the infra-temporal crest of the sphenoid bone to end in the deep surface of the
temporal muscle. The posterior of these two nerves may arise in common with
the masseteric nerve.
(2) The masseteric nerve passes between the bone and the external pterygoid
muscle external to the temporal nerves, and accompanies the masseteric artery
through the sigmoid notch of the mandible to be distributed to the masseter. It
MANDIBULAR DIVISION OF THE FIFTH NERVE
803
may be readily traced through the deeper fibres of the masseter nearly to the
anterior border of that muscle. As it emerges from under cover of the external
pterygoid it gives a twig to the temporo-mandibular articulation.
(3) The nerve to the external pterygoid, after a course of about an eighth of an
inch, divides into twigs which enter the deep surface of the two heads of the muscle.
It is usually adherent at its origin to the long buccal nerve.
(4) The long buccal nerve passes between the two heads of the external pterygoid
muscle, and then turns forwards and emerges from under cover of the temporal and
masseter muscles at the anterior border of the latter. It runs forwards and com-
municates with the buccal branch of the facial, being in this situation covered
only by the integument and fascia, and then pierces the buccinator muscle and
ramifies in on the mucous membrane lining the cheek, its terminal twigs reaching
as far forwards as the angle of the mouth. As it emerges from between the heads
of the external pterygoid, it gives off a slender twig to the temporal muscle.
The POSTERIOR PORTION of the mandibular division of the fifth nerve divides into
three large branches; two of these, the auriculo-temporal and the lingual, are
exclusively sensory; the remaining branch, mandibular (inferior dental), contains a
strand of motor fibres-the mylo-hyoid nerve.
(1) The auriculo-temporal nerve arises by two roots, which usually embrace the
middle meningeal artery, and passes backwards and outwards between the internal
lateral ligament of the temporo-mandibular articulation and the condyle of the
mandible, closely embracing the capsular ligaments of the joint. It then ascends
under cover of the parotid gland and traverses the glandular substance as it
crosses the root of the zygoma. It accompanies the temporal artery, being placed
under cover of and slightly behind that vessel, and terminates at the level of the
tragus of the ear by dividing into auricular and temporal branches. As it passes
through the parotid gland it communicates with the temporo-facial division of the
facial nerve by two stout twigs, which may surround the temporal artery. The
auriculo-temporal nerve receives communicating twigs from the otic ganglion, and
gives off the articular branch, the nerves to the meatus, and the parotid branches.
It terminates in the anterior auricular and superficial temporal branches.
(a) The communicating twigs from the otic ganglion join the nerve close to its
commencement in the form of several fine filaments.
These filaments have been shown by physiological experiments to be derived from the
glosso-pharyngeal nerve through the lesser superficial petrosal. They run for a short
distance in the trunk of the auriculo-temporal, and leave it under the name of parotid
branches. They are the secreto-motor fibres of the parotid gland.
(b) The articular branch is supplied to the temporo-mandibular articulation as
the auriculo-temporal nerve is passing between the capsular ligament and the parotid
gland.
(c) The nerves to the meatus, two in number, pass between the bony and
cartilaginous parts of the external auditory meatus and supply the skin lining the
meatus. The upper of the two nerves furnishes a filament to the membrana
tympani. The lower nerve gives twigs to the lobule of the ear. Occasionally only
the upper nerve is present, the lower being replaced by a twig from the great
auricular. (Henle.)
(d) The parotid branches are a variable number of fine twigs which arise either
directly from the auriculo-temporal nerve or from the loops of communication.
between it and the facial. As above mentioned, they supply the glandular substance.
(e) The anterior auricular branches, two in number, are supplied to the upper
part of the pinna, and are chiefly distributed to the integument which covers the
anterior aspect of the tragus and helix.
f) The superficial temporal branches divide at acute angles and ramify over
the integument which covers the temporal fascia. The largest twig accompanies


3 F2
804
THE NERVOUS SYSTEM
the posterior branch of the temporal artery. The anterior twigs communicate
with the temporal branches of the facial nerve.
(2) The mandibular (inferior dental) nerve is the largest branch of the man-
dibular division. It passes downwards under cover of the external pterygoid muscle
to reach the interval between the ramus of the lower jaw and the spheno-mandibular
ligament. In this situation it is placed on the outer side and somewhat behind
the lingual nerve, and is connected to the latter by a transverse communicating
branch. It then enters the mandibular canal accompanied by the mandibular
artery, and lies at first behind and then below that vessel as it follows the course
of the canal. Opposite the mental foramen it terminates by dividing into an incisive
and a mental branch. The branches of the inferior dental nerve are the mylo-hyoid,
the alveolar, the incisive, and the mental.
(a) The mylo-hyoid is given off from the mandibular nerve immediately before
the latter enters the dental canal. It runs downwards and forwards in the mylo-
hyoid groove of the mandible between the bone and the internal pterygoid muscle.
In this course it is accompanied by the mylo-hyoid artery. It then runs forwards
on the inferior surface of the mylo-hyoid muscle, and, after supplying that muscle
with several twigs, it pierces the anterior belly of the digastric, in the substance of
which it ends.
(b) The alveolar branches are a series of twigs which are given off within the
mandibular canal to supply the molar and bicuspid teeth. They communicate with
one another within the bone, forming a fine plexus. From this plexus twigs are
given off corresponding in number to the fangs of the teeth, and enter the minute
apertures at the tips of the fangs to end in the pulp. Twigs are also given to the
adjacent part of the gums (nervi gingivales).
(c) The incisive branch, the smaller of the two terminal divisions, is continued
forwards and inwards in the dental canal, and supplies the canine and incisor
teeth and the corresponding region of the gums.
(d) The mental branch is a nerve of considerable size, which emerges through the
mental foramen. It communicates, near its exit, with the supramandibular branch
of the facial nerve, and then divides into three branches. The smallest branch turns
downwards to supply the chin. The other two pass upwards, diverging as they
ascend, and divide into a number of twigs. The stoutest twigs ramify upon the
mucous membrane which lines the lower lip. Other twigs are distributed to the
integument and fascia of the lip and chin.
(3) The lingual (formerly called gustatory) nerve is slightly smaller than the
mandibular nerve, and is placed at first in front of and close to the inner side of
the latter under cover of the external pterygoid muscle. In this situation it is
joined by the chorda tympani nerve; the latter enters the lingual on its outer side,
the two nerves uniting at an acute angle. The lingual then escapes from under
cover of the external pterygoid muscle, and is connected to the mandibular nerve
by a transverse communicating branch. It then passes between the ramus of the
mandible and the internal pterygoid muscle, and is continued forwards between the
mucous membrane of the mouth and the mylo-hyoid muscle, and lies on the origin
of this muscle close to the bone. In this part of its course it can be easily divided
by an incision through the mucous membrane at the level of the second lower
molar tooth. It then runs between the mylo-hyoid and hyo-glossus muscles,
crosses below Wharton's duct, and finally courses forwards by the side of the
tongue, so as to reach the tip of that organ. As it crosses the hyo-glossus muscle
it forms a curve with the convexity directed downwards, and is connected at the
most dependent part of the curve to the submandibular (submaxillary) ganglion, to
which it furnishes sensory roots. Immediately beyond the ganglion it communi-
cates freely with the hypoglossal nerve, the communications forming several loops.
Branches. (a) Communicating branches are given to the mandibular nerve, to

MANDIBULAR DIVISION OF THE FIFTH NERVE
805
the submaxillary ganglion, and to the hypoglossal nerve. These have already been
described.
(b) Twigs are distributed to the interval between the tongue and gums, and
ramify in the mucous membrane of the floor of the mouth.
(c) A twig enters the sublingual gland. This twig conveys secreto-motor fibres
from the chorda tympani to the gland.
(d) The lingual branches are a series of twigs which are given off by the lingual
nerve in the last stage of its course as it is passing forwards towards the tip of the
tongue. They pierce the musculature at the side of the tongue, and proceed to the
dorsum of the middle and anterior part of that organ, where they end in the filiform
and fungiform papillæ.
SUBMANDIBULAR (SUBMAXILLARY) GANGLION
The submandibular ganglion is a small reddish fusiform body which is placed
between the mylo-hyoid and hyo-glossus muscles at the outer side of Wharton's
duct. It is connected to the lingual nerve by two communications, an anterior
and a posterior. The posterior communication contains the motor and sensory
roots of the ganglion. The anterior communication represents a branch passing
from the ganglion to the lingual nerve. The motor root is derived from the
The sensory root is furnished by the lingual. The ganglion
also receives a sympathetic root from the plexus of the sympathetic which accom-
panies the facial artery.
chorda tympani.

Branches. The ganglion furnishes five or six twigs to the submandibular
(submaxillary) gland, and gives minute twigs to Wharton's duct, which accompany
the duct to its termination. From the fore part of the ganglion a branch passes
to the lingual nerve, and through this branch fibres from the chorda tympani are
conveyed to the sublingual gland and to the tongue.
Sublingual ganglion.-A small ganglion has been described by Blandin and
others on the twig to the sublingual gland. According to Bose, it is not constant.
OTIC GANGLION
The otic ganglion, or ganglion of Arnold, is a small reddish-grey body which
is placed immediately below the foramen ovale, internal to the mandibular division
of the trigeminal nerve. The cartilage of the Eustachian tube is placed close to its
inner side, and the middle meningeal artery is behind it. The ganglion is oval in
form, and compressed in its coronal diameter. It is greatest in its sagittal diameter,
which is about four millimetres.
Roots. The mandibular division of the trigeminal nerve supplies one or more
roots to the otic ganglion; these roots probably contain both sensory and motor
fibres, and are associated with the nerve to the internal pterygoid. The lesser
superficial petrosal nerve enters the ganglion, being a motor (or, more properly,
efferent) root. The ganglion receives a sympathetic root from the plexus which
surrounds the middle meningeal artery.
Branches. The otic ganglion furnishes muscular twigs to the tensor palati and
tensor tympani; these twigs, especially the former, pass for the most part from the
mandibular division of the fifth nerve to the muscles without interruption in the
nerve-cells of the ganglion. It also gives communicating branches to the auriculo-
temporal nerve and to the chorda tympani.

SIXTH OR ABDUCENT NERVE
The sixth or abducent nerve arises from an approximately spherical cluster of
nerve-cells which is placed between the grey matter of the floor of the fourth

806
THE NERVOUS SYSTEM
ventricle and the formatio reticularis. This nucleus is situated near the middle
line, a little in front of the striæ acusticæ, and corresponds to the eminentia teres.
It is on a line with the nuclei of the third and fourth nerves. The fibres which
arise from this nucleus plunge forwards through the substance of the pons, and
emerge at the lower border of the latter structure (superficial origin). Some of the
fibres pass through the pyramidal body; others pass out in the interval between
the latter and the olivary body.
The sixth nerve was formerly described as giving fibres of origin to the facial, but Gudden
and Gowers have shown that this is not the case. A remarkable strand of fibres passes
from the abducens nucleus to the posterior longitudinal bundle. It runs brainwards, forming
the inner border of the bundle, and decussates below the corpora quadrigemina with its
fellow of the opposite side; it then joins the third nerve, and passes eventually into the
internal rectus muscle. Thus the eyes can be directed to the right or left, as the case may
be, by the action of a single nucleus, e.g. in turning the eyes to the right, the right external
rectus and the left internal rectus are used, and these are both supplied by the right abducens
nucleus.
The sixth nerve pierces the dura mater at a point a little above the junction of
the basilar process of the occipital bone with the sphenoid. It runs upwards on
the body of the sphenoid, and turns forwards in the interval between the apex of
the petrous portion of the temporal bone and the posterior clinoid process of the
sphenoid, passing in this situation under cover of a ligament which connects the
osseous prominences above mentioned. It enters the floor of the cavernous sinus,
and passes on to the outer side of the internal carotid artery. In this situation it
receives several communications from the carotid plexus of the sympathetic. It
enters the orbit through the sphenoidal fissure, passing between the inferior division
of the third nerve and the ophthalmic vein. It passes between the two heads of
the external rectus muscle, and ends by piercing the ocular surface of that muscle.
SEVENTH OR FACIAL NERVE
The seventh or facial nerve is formed by two distinct parts-the main trunk,
or facial nerve proper, and an accessory portion, the pars intermedia of Wrisberg.
The facial nerve proper arises from an elongated nucleus which is deeply placed in
the reticular formation below the floor of the fourth ventricle. This nucleus
commences at the level of the striæ acusticæ, and extends brainwards for about
four millimetres. The fibres which arise from it pursue a remarkably tortuous
course within the substance of the pons. At first they pass backwards and inwards
so as to approach the ependyma of the floor of the fourth ventricle close to the
sulcus longitudinalis medianus (crus of origin). They then run upwards and for-
wards in a compact bundle (fasciculus teres, or ascending crus), which produces
an elevation (eminentia teres) on the floor of the fourth ventricle immediately
external to the median fissure. The bundle of fibres then bends, and is directed
at right angles to its former course; it arches outwards over the nucleus of the
sixth nerve, and passes forwards, outwards, and downwards (issuing crus). In this
part of its course it passes to the outer side of its own nucleus, between the latter
and the ascending root of the fifth nerve. Finally it emerges at the lower border of
the pons in the interval between the olivary and restiform body (superficial origin).
From the above description, it will be seen that the facial nerve embraces the
nucleus of the abducens; the term genu nervi facialis is applied to the nerve in
this part of its course.
The pars intermedia of Wrisberg arises from the extreme upper (proximal) end
of the sensory nucleus of the glosso-pharyngeal nerve (Duval). Its fibres pass
obliquely through the substance of the pons, and emerge at the lower border of the
last-named structure immediately external to the facial nerve, between the latter

FACIAL NERVE
807
and the auditory nerve (superficial origin). From thence the nerve passes, in the
form of a small compact bundle, and enters the internal auditory meatus. In this
situation it lies on the upper surface of the auditory nerve, while the facial is
placed above it. It joins the facial nerve at the commencement of the geniculate
ganglion.
This nerve is regarded as an aberrant fasciculus of the glosso-pharyngeal nerve, and
additional support is given to this view by the fact that it also receives fibres from the
funiculus solitarius (Testut). The chorda tympani is usually regarded as the continuation
of this nerve, and thus the anterior part of the tongue receives fibres from the glosso-
pharyngeal through the chorda tympani, while the posterior part of the organ is supplied
directly. (See GLOSSO-PHARYNGEAL NERVE.)
At its superficial origin the facial nerve is placed immediately internal to the
auditory nerve, the pars intermedia of Wrisberg intervening between them. As
the facial nerve enters the internal auditory meatus, it is placed above the auditory
nerve. It then parts company with the auditory nerve by entering the aqueduct
of Fallopius. While traversing the aqueduct, it necessarily follows the windings
of that canal. It passes at first outwards and forwards through the bone above-

FIG. 448.-DIAGRAMMATIC LATERAL VIEW OF THE ORIGIN OF THE FACIAL
NERVE. (Krause.)
SUPERIOR OLIVE
ASCENDING CRUS
NUCLEUS OF ABDUCENS
CRUS OF ORIGIN
VII
VI
PONS
NUCLEUS OF FACIAL
MEDULLA
OLIVARY NUCLEUS
and between the cochlea and the vestibule. It then makes a sharp bend, and runs
backwards and slightly downwards, being separated from the tympanum in this
part of its course only by a very thin scale of bone and by the mucous membrane
lining the cavity. Lastly, it runs directly downwards, and emerges at the stylo-
mastoid foramen. The portion of the nerve corresponding to the first bend is
considerably thickened, and contains some nerve-cells; it is called the geniculate
ganglion. The ganglionic substance forms a little conical cap on the bend of the
nerve, the apex of the cone being directed towards the hiatus Fallopii.
After its emergence from the stylo-mastoid foramen, the facial nerve runs
downwards and forwards within the substance of the parotid gland, and terminates
by dividing into two divisions-an upper or temporo-facial, and a lower or cervico-
facial.
The branches of the facial nerve may be classified into three sets:-(1) Branches
given off within the aqueduct of Fallopius; (2) branches from the extracranial
portion of the nerve before its terminal division; (3) branches of the temporo-facial
and cervico-facial divisions.
(1) Six branches are given off within the aqueduct : viz. three from the genicu-
late ganglion, the great, the lesser, and the external superficial petrosal nerves;
and three from the facial nerve in the descending part of its course-viz. the nerve
to the stapedius, the chorda tympani, and a communicating twig to the pneumo-
gastric.

808
THE NERVOUS SYSTEM
ป
(a) The great superficial petrosal nerve receives a communicating filament from
the tympanic branch of the glosso-pharyngeal, and leaves the aqueduct by passing
through the hiatus Fallopii. It runs forwards and inwards in a groove on the
petrous portion of the temporal bone under cover of the dura mater. It passes
beneath the Gasserian ganglion, and pierces obliquely the cartilaginous substance
which occupies the foramen lacerum medium; here it is joined by the great deep
petrosal nerve, and forms, with the latter, the Vidian nerve as already described.
(b) The lesser superficial petrosal nerve arises from the geniculate ganglion
external to the preceding. It receives a relatively large communication from the
tympanic branch of the glosso-pharyngeal. This communication is often considered
to be the main root of the nerve (Schwalbe and others). It leaves the aqueduct
through a canal which is placed external to the hiatus Fallopii, and passes forwards
for a short distance, lying in a groove in the bone, under cover of the dura mater.
It escapes from the cranium through a small foramen situated between the fora-
men ovale and the foramen spinosum (canalis innominatus), and enters the etic
ganglion. Occasionally it leaves the skull by traversing the suture between the
great wing of the sphenoid and the petrous portion of the temporal bone.
(c) The external superficial petrosal is the smallest of the three petrosal nerves.
It passes through a minute canal in the temporal bone immediately external to the
point of emergence of the lesser superficial nerve. It then runs forwards, under
cover of the dura mater, and joins the plexus of the sympathetic on the middle
meningeal artery close to the foramen spinosum.
(d) The nerve to the stapedius is a minute twig which is given off by the facial
nerve immediately below the second bend which the nerve forms within the aque-
duct. It passes through a small canal leading from the aqueduct to the interior of
the pyramid, and ends in the muscular substance of the stapedius.
(e) The chorda tympani arises from the facial nerve about five millimetres above
the stylo-mastoid foramen. It pursues a slightly recurrent course, upwards and
forwards, through the iter chorda posterius, and thus enters the tympanum. It
crosses the membrana tympani at the junction of the upper and middle thirds of
that membrane. In this part of its course it runs forwards between the fibrous and
mucous layers of the membrana tympani, passing on the inner side of the manu-
brium of the malleus. It leaves the tympanum by passing through the iter chordæ
anterius, or canal of Huguier, and, after communicating with the otic ganglion,
passes forwards, under cover of the external pterygoid muscle, to gain the outer side
of the lingual nerve, which it joins at an acute angle. From thence it runs in the
sheath of the lingual nerve, a portion of its fibres, as already described (see LINGUAL
NERVE), passing into the submandibular ganglion. Other fibres reach the sublingual
gland, and the dorsum of the tongue.
(f) The communicating twig to the pneumogastric is given off at the same level
as the chorda tympani, and joins the auricular branch of the pneumogastric while
the latter is traversing the substance of the temporal bone.
(2) The branches which arise from the facial nerve between the stylo-mastoid
foramen and the terminal bifurcation are the posterior auricular and the nerves to
the posterior belly of the digastric and to the stylo-hyoid muscles. A lingual
branch is also described.
(a) The posterior auricular nerve is the first branch of the extracranial portion
of the facial. It passes between the parotid gland and the anterior border of the
sterno-mastoid muscle, and runs upwards in the deep interval between the external
auditory meatus and the mastoid process. In this situation it communicates with
the auricular branch of the pneumogastric. It supplies the retrahens aurem, and
sends a slender twig upwards to the attollens aurem, and ends in a long slender
branch, which passes backwards to supply the posterior belly of the occipito-
frontalis,

FACIAL NERVE
809
(b) The nerve to the posterior belly of the digastric arises from the facial nerve
close to the stylo-mastoid foramen, and enters the digastric near the centre of that
muscle, or sometimes near its origin.
(c) The nerve to the stylo-hyoid arises at the same level as the preceding nerve,
the two nerves sometimes forming a common trunk. It ends in the upper part of
the muscle for which it is destined.
The lingual branch is remarkable for its long course. It arises close to the two small
muscular nerves above described. It passes on the outer side of the stylo-pharyngeus
FIG. 449.-SUPERFICIAL DISTRIBUTION OF THE FACIAL AND OTHER NERVES OF
THE HEAD. (After Hirschfeld and Leveillé.)
SUPRA-ORBITAL-
PALPEBRAL TWIG
OF LACHRYMAL
INFRATROCHLEAR
TEMPORAL
BRANCH OF
SEVENTH
MALAR BR..
OF SEVENTH
MAXILLARY
DIV. OF FIFTH
INFRA-
ORBITAL
BR. OF SEVENTH
BUCCAL BRANCH
OF SEVENTH
MENTAL BRANCH
OF MANDIBULAR
SUPRAMANDIBULAR
BRANCH OF
SEVENTH
INFRAMANDIBULAR
BRANCH OF SEVENTH
POSTERIOR
AURICULAR
AURICULO-
TEMPORAL
GREAT
OCCIPITAL
FACIAL
LESSER OCCIPITAL
-GREAT AURICULAR
SUPERFICIAL
CERVICAL
muscle, and gains the side of the pharynx. In this situation it is joined by filaments from
the glosso-pharyngeal. It then passes between the palato-glossus muscle and the tonsil,
and reaches the base of the tongue, where it ends in filaments to the mucous membrane
and in twigs to the palato-glossus and stylo-glossus muscles. (Testut.)
(3) Six branches are given off from the two terminal divisions of the facial
nerve. These branches traverse the substance of the parotid gland, and emerge at
its margin. At their emergence they range from a point on the zygoma, a little in
front of the spot where the temporal artery crosses the bone, to the angle of the

810
THE NERVOUS SYSTEM
T
ง
lower jaw. These branches proceed forwards over the face and front of the neck,
and by frequently communicating with one another form a great expanded plexus
which is called the pes anserinus. Taken in order from above downwards, the
temporo-facial division gives off the following branches: temporal, malar, and
infraorbital. The cervico-facial division divides into buccal, supramandibular
and inframandibular branches.
The TEMPORO-FACIAL DIVISION of the facial nerve runs obliquely upwards and
forwards through the substance of the parotid gland, crosses the external carotid
artery and the temporo-maxillary vein on the superficial aspect of those vessels,
and terminates, as above described, in three branches.
In this course it receives communications from the auriculo-temporal nerve, as
mentioned in the description of the fifth nerve.
(a) The temporal branch passes upwards through the parotid gland, and emerges
at the upper border of the gland at a point a little in front of the temporal artery.
It divides into several branches, which communicate with one another and with the
malar branch. It also communicates with the temporal branch of the orbital, and
with the supraorbital nerve. Its largest branches are distributed to the upper
part of the orbicularis palpebrarum, and to the anterior belly of the occipito-
frontalis. It also supplies the attrahens aurem, the corrugator supercilii, and,
occasionally, the attollens aurem.
The fibres which run in the facial nerve to end in the orbicularis palpebrarum and
frontalis muscles are probably derived from the oculo-motor nucleus of the same side,
and pass downwards in the posterior longitudinal bundle to join the genu nervi facialis.
(Mendel.)
(b) The malar branch is a smaller nerve than the preceding. It is directed
upwards and forwards to reach the most prominent part of the malar bone; it
supplies the lower part of the orbicularis palpebrarum. It also gives twigs to both
eyelids; it communicates with the malar branch of the orbital, with the supra-
orbital and lachrymal branches of the ophthalmic, with the palpebral twigs
derived from the superior maxillary division of the fifth, and with the temporal
and infraorbital branches of the facial.
(c) The infraorbital is the largest of the nerves which enter into the pes anserinus.
It escapes from the parotid gland above Stenson's duct, and divides into several
branches. These branches communicate freely with one another, and pass inwards
on the deep surface of the zygomatici and the levator labii superioris. Under cover
of the latter muscle they communicate with the terminal branches of the superior
maxillary division of the fifth nerve, forming the infraorbital plexus; from thence
twigs extend to the nose, and communicate with the nasal branch of the ophthalmic
nerve. The infraorbital branch also forms communications with other branches
of the facial, namely with the malar above and with the buccal below. It supplies
the zygomatici, the levator labii superioris, the levator labii superioris alæque nasi,
the levator anguli oris, the pyramidalis nasi, the compressor nasi, and the depressor
alæ nasi. It also gives twigs to the buccinator and to the orbicularis oris.
The CERVICO-FACIAL DIVISION of the facial nerve is directed forwards and down-
wards, through the parotid gland, and, like the temporo-facial division, it crosses
on the outer side of the external carotid artery. As it traverses the glandular sub-
stance, it communicates with the facial branches of the great auricular nerve. As
above described, it terminates in three branches: the buccal, the supramandibular,
and the inframandibular.
(a) The buccal branch is of small size, and is the highest of the three branches
of the cervico-facial division. It is placed between the infraorbital and supra-
mandibular branches of the facial, and communicates with both these branches. It
emerges from the parotid gland below Stenson's duct, and crosses the masseter
muscle. In front of the anterior border of the masseter, it communicates with the
FACIAL NERVE-AUDITORY NERVE
811
long buccal branch of the fifth, and then breaks into twigs, which end in the
buccinator and orbicularis oris.
(b) The supramandibular branch, after escaping from the parotid gland, crosses
the lower part of the masseter muscle, a little way above the angle of the lower
jaw, and passes forwards, under cover of the risorius and the depressors of the
lower lip, as far as the middle line. It communicates with the buccal and
inframandibular branches of the facial, and with the mental branch of the man-
dibular nerve. It supplies the risorius, the depressor anguli oris, the depressor
labii inferioris, and the levator menti.
(c) The inframandibular branch becomes superficial at the lower margin of the
parotid gland, and runs obliquely downwards and forwards, under cover of the
platysma, across the side and front of the neck. It forms one or more communi-
cating loops, near its commencement, with the great auricular nerve, and longer
loops, lower down, with the superficial cervical nerve. It supplies the platysma
myoides.
EIGHTH OR AUDITORY NERVE
The auditory nerve appears at the lower border of the pons (superficial origin),
immediately external to the facial nerve. It arises by two roots, a lateral and a
mesial. These roots embrace the restiform body, the lateral root being external, and
FIG. 450.-TRANSVERSE SECTION OF THE PONS, PASSING THROUGH THE MOST
DISTAL OF THE STRIE MEDULLARES.
STRIA
MEDULLARIS
NUCLEUS OF
HYPOGLOSSAL
(Krause.)

CHIEF NUCLEUS OF
AUDITORY NERVE
VENA CENTRALIS
RAPHE
OLIVARY NUCLEUS
NUCLEUS PONTIS.
CONTINUATION OF
PYRAMIDAL BODY
VIII
RESTIFORM BODY
SUBSTANTIA
GELATINOSA
ACCESSORY NUCLEUS
MESIAL ROOT
the mesial root internal to that body (fig. 450). It is very generally agreed that
the lateral root (superficial, dorsal, inferior, or posterior root) is continuous with
the cochlear nerve, and is the true nerve of hearing; while the mesial root (deep,
ventral, superior, or anterior root) is continued into the vestibular nerve, and is
concerned in the maintenance of equilibrium. The nuclei in connection with
these roots will be first described.
The small-celled or chief nucleus is superficially placed in the floor of the
fourth ventricle. It is largest in the region of the striæ medullares, in which
situation it appears in coronal sections as a triangular grey mass, which reaches
the middle line. It extends forwards from this point as far as the abducens
nucleus and backwards for about an equal distance. Both in front and behind

812
THE NERVOUS SYSTEM
it recedes from the middle line. The nerve-cells forming this nucleus are all of
small size.
The large-celled or Deiter's nucleus is placed close to the inner side of the
restiform body. It is about the same length as the small-celled nucleus, but
occupies a position deeper and further forwards than the latter. The cells of this
nucleus are of large size, and are most numerous at the anterior part.
The accessory nucleus is a group of cells chiefly contained within the lateral
root, but also occupying the angular interspace between the lateral and the mesial
roots. It presents marked affinities to a spinal nerve-ganglion, particularly in the
character of the nerve-cells in its anterior (superior) part.
The nerve-cells in the tuberculum acusticum are also connected with the
auditory nerve. The so-called nucleus funiculi teretis (a group of cells which is
placed on the mesial side of the chief nucleus), and the superior olive may also be
mentioned as parts of the auditory apparatus.
Lateral root.-The lateral root arises chiefly from the cells of the accessory
nucleus, but a certain number of fibres are believed to pass by that nucleus without
interruption. Both sets of fibres pass in a tolerably compact bundle around the
outer side of the restiform body. A certain number take origin in the cells of
the tuberculum acusticum, the others cross the floor of the fourth ventricle, as
striæ medullares, and, having crossed the middle line, take origin partly in the
so-called nucleus funiculi teretis of the opposite side, and pass partly into the
conductor sonorus. The origin of the conductor sonorus is unknown; its course
has been noticed in the description of the fourth ventricle (page 758).
Fibres pass inwards from the accessory nucleus, and traverse the substance of
the pons in a transverse direction to reach the superior olive of the same and of
the opposite side. In many animals, owing to the relatively feeble development
of the pons, these fibres appear on the ventral surface of the brain and occupy a
quadrilateral area on each side, external to the pyramidal body, and in front of
(above) the inferior olive. For this reason these fibres are collectively called the
corpus trapezoides.
Mesial root. In coronal sections, taken through the medulla at a point
corresponding to the centre of the medullary portion by the floor of the fourth
ventricle, the cross-section of a bundle of fibres is seen on the inner side of the
nucleus cuneatus; this is the ascending.root of the auditory nerve. The ascending
root is continued into the region of Deiter's nucleus, and is here joined by fibres
from the large cells of Deiter's nucleus and by others from the chief nucleus. The
fibres derived from these several sources pass ventrally between the restiform body
and the ascending root of the trigeminal nerve, and form the mesial root.
Many other origins of the auditory nerve have been described, the cerebellar
root being, perhaps, the most important of these. The chief nucleus receives
fibres which are derived from the flocculus of the opposite side (Edinger). Fibres
from the nucleus fastigii of the opposite side reach the cells of Deiter's nucleus, and
are probably continued into the mesial root.
There appears to be but little doubt that the superior temporal convolution is
the cortical centre for hearing (Ferrier). According to Obersteiner, the probable
links between the nerves of hearing and the cortical acoustic field are as follow:
lateral root, accessory nucleus, superior olive, inferior fillet, posterior quadrigeminal
body, internal geniculate body, temporal lobe.
From its superficial origin, the auditory nerve proceeds upwards, outwards, and
forwards, winding round the middle cerebellar peduncle, and enters the internal
auditory meatus. Near the end of that bony canal it divides into an anterior or
cochlear, and a posterior or vestibular division. In its course through the meatus,
it is accompanied by the facial nerve, the pars intermedia, and the internal audi-
tory artery.
These structures are all contained in a common sheath of arachnoid.

GLOSSO-PHARYNGEAL NERVE
813
Within the meatus the auditory nerve becomes flattened, and is curved in such
a manner as to form a half-cylinder, open above. The pars intermedia lies in the
concavity of this half-cylinder, and above this is the facial nerve, the three nerves
being connected by a lax connective tissue. This connective tissue has often been
mistaken for nervous communications. (Testut.)
The cochlear nerve gives twigs to the saccule and to the ampulla of the
posterior semicircular canal, and then divides into a number of filaments, which
enter the lamina cribrosa.
The vestibular nerve divides into twigs for the utricle and for the ampullæ of
the superior and external semicircular canals.
NINTH OR GLOSSO-PHARYNGEAL NERVE
The glosso-pharyngeal nerve is made up of fibres derived from three different
Sources. Two of these sets of fibres arise from distinct groups of cells, and
represent the motor part of the nerve and the portion devoted to the special sense
of taste. The third set of fibres takes the form of an ascending root (funiculus
solitarius), the round cross-section of which forms a conspicuous object in sections
through the lower part of the medulla. The fibres which form this ascending (or
sensory) root have not as yet been distinctly traced to cells. The fibres from these
three sources emerge in the form of several fasciculi (superficial origin) in the groove
between the olivary and restiform bodies, near the lower border of the pons, in
series with the roots of the vagus nerve.
The two principal nuclei are called the small-celled and the large-celled nuclei,
and are absolutely continuous with the nuclei of the vagus and of the accessory
part of the spinal accessory nerve.
The small-celled nucleus (sensory, or accessorio-vago-glosso-pharyngeal nucleus)
corresponds for the most part to the ala cinerea in the floor of the fourth ventricle.
In this situation it lies immediately external to the chief nucleus of the hypo-
glossal nerve. Higher up, it recedes from the middle line, and is more deeply
placed, being covered by the chief nucleus of the auditory nerve. It is from this
deeper (upper) part that the glosso-pharyngeal fibres take origin and these fibres are
regarded as the conductors of the special sense of taste.
The large-celled nucleus (motor nucleus, nucleus ambiguus) contains cells
resembling the motor cells in the anterior horn of the spinal cord, and is regarded
as a portion of the head of that horn which has been amputated from the neck by
the decussation of the pyramids. It is more deeply placed than the small-celled
nucleus. It is placed between the nucleus lateralis and external accessory olive, and
somewhat dorsally to both. It extends in a sagittal direction from the level of the
striæ medullares downwards to a point a little below the fourth ventricle. From
the upper end of this nucleus fibres pass dorsally and then arch outwards to join
the fibres derived from the small-celled nucleus. Both sets of fibres then proceed
forwards and outwards, piercing the ascending root of the trigeminal, and emerge
at the ventral margin of the restiform body.
The ascending root (funiculus solitarius) commences at a point immediately
above the level of the decussation of the pyramids. It passes upwards in the form
of a sharply circumscribed round bundle, gaining in strength as it ascends. It is
placed at first close to the outer side of the nucleus of the hypoglossal nerve;
higher up it is related to the outer side of the small-celled (accessorio-vago-glosso-
pharyngeal) nucleus, and lies dorsally to the roots of the vagus between the latter
and the ascending root of the auditory. Finally, at the level of the striæ medullares,
it bends at right angles to its former course, and runs forwards and outwards,
traversing the substantia gelatinosa and the ascending root of the trigeminal to join


814
THE NERVOUS SYSTEM
४
the rest of the glosso-pharyngeal nerve, forming the uppermost (most proximal) of
the series of fasciculi which has been described as the superficial origin of that nerve.
The origin of the ascending root is not known with certainty; but it is probably
derived from the posterior horn.
From its superficial origin the glosso-pharyngeal nerve proceeds outwards and
slightly forwards, below and in front of the flocculus, to reach the middle compart-
ment of the jugular foramen, which it traverses in common with the vagus and
spinal accessory nerves. As it passes through the foramen it is placed in front
of, and a little internal to, the vagus and spinal accessory nerves, but occupies a
separate compartment in the dura mater, and is lodged in a groove on the lower
border of the petrous portion of the temporal bone. Having emerged at the base
of the skull, it lies at first in contact with the vagus, but leaves the latter almost
immediately and passes forwards and inwards between the internal jugular vein
and the internal carotid artery and curves round the outer side of the latter vessel.
In this part of its course it is placed under cover of the stylo-pharyngeus muscle.
It then winds round the lower border of that muscle, and finally passes upwards in
front of it and gains the deep surface of the hyo-glossus, where it breaks up into its
terminal or lingual branches. In the course above described, the glosso-pharyngeal
describes a curve with the convexity directed downwards and backwards.
In its course through the jugular foramen, two ganglia are formed upon the
trunk of the nerve, the lower of these bodies (petrous ganglion) is the more constant,
the upper or jugular ganglion being generally regarded as a segmentation from the
petrous ganglion. The two ganglia taken together are generally assumed to be
equivalent to the ganglion on the posterior root of a spinal nerve.
The jugular ganglion (ganglion of Ehrenritter) is a small greyish body which
involves only the back part of the nerve. It is lodged in the upper part of the
groove in the temporal bone through which the nerve passes. This ganglion does
not give off any branches.
The petrous ganglion (ganglion of Andersch) is an ovoid greyish body which
probably involves all the fibres of the nerve. Its long axis coincides with the axis
of the nerve, and measures two or three millimetres. It is placed in the lower part
of the jugular fossa. The nerve of Jacobson and some communicating branches
arise from this ganglion.
Branches. The following branches are given off by the glosso-pharyngeal
nerve: (1) meningeal; (2) tympanic; (3) communicating; (4) muscular;
(5) pharyngeal; (6) tonsillar; and (7) lingual.
(1) The meningeal branches are slender twigs which are given off within the
cranium, and are distributed to the pia mater and arachnoid. (Bochdalek.)
(2) The tympanic branch, or nerve of Jacobson, is a small twig which arises
from the petrous ganglion. It enters a minute canal (the tympanic canaliculus),
which commences below on the ridge between the jugular fossa and the inferior
opening of the carotid canal, and ends above, in the tympanic cavity, immediately
below the promontory. The nerve, having traversed this canal, ramifies on the
promontory, grooving the bone, and forms the tympanic plexus. The following
branches arise from the nerve within the tympanum: (a) a communicating twig
to the great superficial petrosal; (b) a twig to the lesser superficial petrosal, which
is considered by some anatomists to be the main root of the nerve; (c) a twig to
the mucous membrane surrounding the fenestra ovalis; (d) a twig to the fenestra
rotunda; (e) a twig to the lining membrane of the Eustachian tube; (f) a twig
which passes through the carotico-tympanic canal to join the carotid plexus of the
sympathetic.
(3) The communicating branches arise from the petrous ganglion. One joins,
the superior cervical ganglion of the sympathetic; another forms a loop with the
auricular branch of the vagus; while a third, less constant than the other two, joins
PNEUMOGASTRIC NERVE
815
the ganglion of the root of the vagus. Immediately below the petrous ganglion
a twig is given off which joins the lingual branch of the facial as above
described (page 809).
(4) The muscular branch is distributed to the stylo-pharyngeus muscle. This
branch receives a communication from the facial.
According to Testut, the glosso-pharyngeal gives off carotid branches which join the
carotid plexus of the sympathetic and also muscular twigs to the digastric, stylo-hyoid, and
stylo-glossus muscles.
(5) The pharyngeal branches may be two or three in number, and arise from
the nerve a short distance below the petrous ganglion. The principal and most
constant of these nerves passes on the outer side of the internal carotid artery, and
after a very short independent course joins the pharyngeal branch of the vagus to
form the pharyngeal plexus with that nerve, and with branches of the superior
cervical ganglion.
(6) The tonsillar branches are a number of small twigs which arise under cover
of the hyo-glossus muscle; these proceed to the tonsil, around which they form a
plexus. From this plexus fine twigs proceed to the pillars of the fauces and to the
soft palate.
(7) The lingual branches arise from the termination of the nerve and proceed
to the dorsum of the tongue, where they are chiefly distributed to the circumvallate
papillæ. Some small twigs pass backwards to the follicular glands of the tongue,
and to the anterior surface of its epiglottis. Other twigs are distributed around
the foramen cæcum, where they communicate with the corresponding twigs of the
opposite side.
TENTH OR PNEUMOGASTRIC NERVE
The pneumogastric or vagus nerve is the longest of the cranial nerves. It is
remarkable for its extensive distribution, for the asymmetry which it shows in
certain parts of its course and distribution, and for the almost vertical course which
it pursues. It supplies, as its name implies, the lungs and the stomach, but also
furnishes branches to the external ear, the pharynx, larynx, oesophagus, trachea,
heart, and abdominal viscera.
The pneumogastric nerve arises in the medulla in a manner nearly identical with
the glosso-pharyngeal nerve, the roots of the former nerve being a serial continua-
tion of the roots of the latter. Thus we find that sensory roots arise from the
small-celled nucleus (in a position corresponding to the ala cinerea in the floor of
the fourth ventricle), and motor roots arise from the nucleus ambiguus. The latter
arch round to join the sensory roots. The vagus is also said to receive a few fine
filaments from the funiculus solitarius. The roots from these different sources
unite and pass forwards and outwards to emerge (superficial origin) in the form of
from ten to fifteen fasciculi, between the restiform body and the lateral column of
the medulla. This row of fasciculi is in series above with the glosso-pharyngeal
roots, and below with the bulbar roots of the spinal accessory. The roots of these
three nerves cannot be distinguished from one another either at their superficial
origin, or at the points where they spring from their nuclei in the medulla, unless
the connection of the roots with their respective trunks has been preserved.

It
From its superficial origin the vagus nerve proceeds outwards and slightly
upwards and forwards beneath the flocculus to reach the jugular foramen.
traverses the middle compartment of the foramen accompanied by the spinal
accessory and glosso-pharyngeal nerves The former nerve occupies the same
compartment in the dura mater as the vagus. The glosso-pharyngeal is provided
with a separate sheath, and is in front of and somewhat internal to the other two

816
THE NERVOUS SYSTEM
nerves. As the vagus traverses the jugular foramen it bends at a right angle to its
former course, and proceeds vertically downwards. In its course down the neck it
FIG. 451.-DISTRIBUTION OF THE PNEUMOGASTRIC NERVE, VIEWED FROM BEHIND. (Krause.)
Stylo-hyoid
Ligamentum pharyngeum
Posterior belly of
digastric
Sterno-mastoid"
Rectus capitis
anticus major
Stylo-pharyngeus
Stylo-glossus
Internal pterygoid
SUPERIOR-
CERVICAL
GANGLION
Middle constrictor
X
XI
IX
XII
-Internal carotid
artery
RIGHT
SYMPATHETIC
Occipital artery
Posterior belly of
digastric
Common carotid
artery
Inferior constrictor
GANGLION-
THYROIDEUM
(VARIETY)
THYROID GLAND
Inferior thyroid-
artery
Subclavian artery.
DESCENDENS
HYPOGLOSSI
Common carotid
artery
Sterno-mastoid
TWIG OF
RECURRENT
LARYNGEAL TO
PHARYNGEAL
PLEXUS
-Thyroid axis
INFERIOR
CERVICAL
RECURRENT
LARYNGEAL
NERVE
Thoracic aorta-
Crus of diaphragm
GANGLION
RECURRENT
LARYNGEAL
PLEXUS GULE
RIGHT
PNEUMOGASTRIC
is placed in front of the rectus capitis anticus major and longus colli muscles, but
separated from them by the prevertebral layer of the cervical fascia. In the upper

PNEUMOGASTRIC NERVE
817
part of the neck it is placed between and on a plane posterior to the internal jugular
vein and the internal carotid artery. In the lower part of the neck it occupies a similar
position in regard to the internal jugular vein and common carotid artery, the vein
being in front and external, and the artery in front and internal to the nerve.
three structures are enclosed in a common sheath derived from the deep cervical fascia.
In their course through the thorax the nerves of the left and right sides differ
in some respects from each other.
The
The right vagus nerve passes in front of the first stage of the subclavian artery
between the latter and the right innominate vein, and then, inclining backwards,
runs downwards on the side of the trachea to reach the posterior aspect of the right
bronchus. Behind the bronchus it expands into a great, flat, plexiform band, from
which the posterior pulmonary plexus proceeds. The vagus then inclines inwards
in the form of two cords, and communicates with the pneumogastric of the opposite
side both in front and behind the oesophagus to form the oesophageal plexus (plexus
gulæ). Having interchanged a considerable number of fibres with the other nerve,
the right vagus then descends (having regained the form of one nerve) behind the
œsophagus through the oesophageal opening of the diaphragm, and spreads out on
the posterior surface of the stomach.
The left vagus nerve enters the thorax behind the left common carotid artery
between the latter and the left subclavian artery. As it approaches the arch of
the aorta it bends suddenly backwards, and crosses the root of the subclavian artery
on the left side of that vessel, immediately under cover of the pleura. It then
crosses the left side (in front) of the transverse part of the arch of the aorta, and
bends backwards to reach the posterior aspect of the left bronchus, where it spreads
out in a similar manner to the nerve of the right side. It then descends on the
œsophagus, entering into the plexus gulæ, and on reaching the diaphragm passes
in the form of a single trunk in front of the oesophagus into the abdominal cavity,
and spreads out on the anterior surface of the stomach.
At the base of the skull the vagus presents two ganglia: an upper ganglion, or
ganglion of the root; and a lower, or ganglion of the trunk.
The ganglion of the root is placed within the jugular foramen opposite the jugular
ganglion of the glosso-pharyngeal. It is an irregular greyish swelling of from four to
six millimetres in length. It is usually regarded as corresponding to a spinal ganglion.
The ganglion of the trunk, situated a little below the preceding, is a fusiform
enlargement of the nerve about twenty millimetres in length, and four to five milli-
metres in transverse diameter at its thickest part. The hypoglossal nerve is firmly
attached to it by connective tissue and encloses it in a spiral turn, being placed at first
to the inner side of the vagus, then passing behind, then to its outer side, and finally
crossing it in front. The superior cervical ganglion of the sympathetic is behind and
a little external to the vagus; the glosso-pharyngeal is in front of it. The accessory
portion of the spinal accessory nerve joins the ganglion of the trunk; some of the
fibres running over the ganglion into the pharyngeal and superior laryngeal branches.
Branches. The branches of the vagus may be classified into (1) communicating
branches; and (2) branches of distribution.
(1) Communicating branches. The vagus communicates with the following
nerves:-(a) the glosso-pharyngeal to the auricular branch of the pneumogastric ;.
(b) the spinal accessory; (c) the hypoglossal; (d) the sympathetic; and (e) the
upper two spinal nerves.
(a) Besides the communicating branch to the vagus just referred to, a communi-
cating twig is given off from the pneumogastric, close to the base of the skull,
which joins the glosso-pharyngeal nerve immediately below the petrous ganglion.
(b) The spinal accessory gives some fine filaments to the ganglion of the root of
the vagus within the jugular foramen. Lower down, the remainder of the accessory
portion joins the ganglion of the root.
trunk
3 G
818
THE NERVOUS SYSTEM
7
(c) The hypoglossal furnishes two or three fine filaments to the ganglion of the
trunk of the vagus. These filaments are given off by the hypoglossal as it winds
round the ganglion.
(d) Two or three twigs from the superior cervical ganglion of the sympathetic
join the ganglion of the trunk. Lower down the branches of distribution of the
vagus communicate extensively with the sympathetic.
(e) A twig passes from the loop formed by the anterior primary divisions of the
upper two spinal nerves to the ganglion of the trunk of the vagus. This communi-
cation is not constant.
(2) Branches of distribution. These are (a) the meningeal; (b) auricular;
(c) pharyngeal;√(d) superior laryngeal; (e) inferior laryngeal; (f) cardiac;
(g) pulmonary; (h) oesophageal; and (i) abdominal branches.
(a) The meningeal or recurrent branch is a slender filament which is given off
from the ganglion of the root. It takes a recurrent course through the jugular
foramen, and is distributed to the dura mater around the lateral sinus.
(b) The auricular branch, or nerve of Arnold, arises from the jugular fossa.
It traverses the bone, passing to the inner side of the aqueduct of Fallopius, and
emerges behind the pinna, where it divides into two branches, one of which joins
the posterior auricular branch of the facial while the other supplies the posterior
and inferior part of the external auditory meatus and the back of the pinna.
(c) The pharyngeal branches may be two or three in number. The principal of
these joins the pharyngeal branch of the glosso-pharyngeal in front of the internal
carotid artery, and passes with the latter behind the external carotid artery down-
wards and inwards to reach the posterior aspect of the pharynx. Here the two
nerves are joined by branches from the superior cervical ganglion of the sympathetic,
and form, with the latter, the pharyngeal plexus.
(d) The superior laryngeal nerve arises from the lower part of the ganglion of
the trunk, and passes obliquely downwards and inwards behind both internal and
external carotid arteries towards the larynx. In this course it describes a curve
with the convexity downwards and outwards, and divides into (i) a larger internal
and (ii) a smaller external branch.
(i) The internal branch accompanies the superior laryngeal artery to the interval
between the upper border of the thyroid cartilage and the great cornu of the hyoid
bone. It passes under cover of the thyro-hyoid muscle and pierces the thyro-hyoid
membrane to gain the interior of the larynx; here it divides into a number of
diverging branches. The ascending branches supply the mucous membrane on
both surfaces of the epiglottis. The descending branches ramify in the mucous
membrane lining the larynx, communicate with the recurrent laryngeal nerve, and
supply the mucous membrane which covers the back of the cricoid cartilage.
(ii) The external laryngeal branch runs downwards towards the lower border of
the thyroid cartilage. It pierces the lower fibres of the inferior constrictor of the
pharynx, and ends for the most part in the crico-thyroid muscle. A few filaments
pierce the crico-thyroid membrane, and are distributed to the lining membrane of
the larynx. It gives off a cardiac branch which joins one of the cardiac branches
of the sympathetic; it also furnishes twigs to the inferior constrictor and com-
municating twigs to the pharyngeal plexus.
(e) The inferior or recurrent laryngeal nerve of the right side arises at the root
of the neck in front of the first stage of the right subclavian artery. It hooks round
the artery, passing below and then behind that vessel, and runs upwards and slightly
inwards, crossing obliquely behind the common carotid and inferior thyroid arteries.
Having gained the side of the trachea, it runs upwards in the groove between that
canal and the œsophagus, and enters the larynx by passing under cover of the lower
border of the inferior constrictor of the pharynx. It then breaks up into branches,
which are distributed to all the intrinsic muscles of the pharynx with the exception

PNEUMOGASTRIC NERVE
819
of the crico-thyroid, and communicates, as above mentioned, with the superior
laryngeal nerve. Near its commencement it usually gives off a cardiac branch.
In its course between the œsophagus and trachea it gives numerous twigs to
these structures, and near the termination it furnishes one or two twigs to the
inferior constrictor of the pharynx.
On the left side the nerve arises in front of the so-called transverse portion of the
aortic arch, and winds round the concavity of the arch just behind the obliterated
ductus arteriosus. It crosses obliquely behind the root of the left common carotid
artery, gains the angular interval between the oesophagus and trachea, and corre-
sponds to the nerve of the right side for the remainder of its course and distribution.
(f) Cardiac branches. - These are named (from the different levels at which they
take origin) cervical and thoracic, and form altogether three or four pairs of nerves.
These all proceed to the deep cardiac plexus, with one exception, the inferior
cervical cardiac of the left side, which joins the superficial cardiac plexus.
(i) The superior cervical cardiac nerves, one or two in number, join the corre-
sponding branches from the sympathetic. A full account of these nerves will be
given in the description of the cardiac plexus. (See SYMPATHETIC SYSTEM.)
(ii) The inferior cervical cardiac nerve of the left side passes downwards on
the left side of the transverse portion of the aortic arch between the latter and the
pleura, and joins the superficial cardiac plexus. As it crosses the arch the phrenic
nerve is in front of it, and the left upper cervical cardiac of the sympathetic is
behind it. The right inferior cervical cardiac passes downwards on the side of the
trachea to join the deep cardiac plexus.
(iii) The thoracic cardiac branches usually arise close to and in connection with
the recurrent laryngeal nerves; consequently the nerves on the left side arise a little
lower than the right. They are directed inwards to the front of the lower end of
the trachea to terminate in the deep cardiac plexus.
(g) The anterior pulmonary branches are one or two small twigs, which arise
at the upper border of the root of the lung and pass forwards to gain the anterior
aspect of the bronchus, where they communicate with the sympathetic and form the
anterior pulmonary plexus, whence fine twigs pass on the bronchus into the lung.
The posterior pulmonary plexus is formed by a great flattened expansion of the
pneumogastric nerve on the posterior aspect of the bronchus. From this several
stout twigs proceed, which communicate with twigs from the second, third, and
fourth thoracic ganglia of the sympathetic, and pass into the lung.
(h) Esophageal branches.-Numerous twigs are given off from the plexus gulæ
as it encircles the oesophagus, and are distributed to the muscular and mucous
coats of that canal.
(2) Abdominal branches. The termination of the left vagus nerve passes
through the œsophageal opening in the diaphragm on the anterior aspect of the
œsophagus, and is distributed over the anterior surface of the stomach. The
strongest branches accompany the coronary artery along the lesser curvature of the
stomach, and, from these, twigs pass on to the hepatic artery and join the hepatic
plexus. The termination of the right vagus is distributed upon the posterior sur-
face of the stomach, and gives twigs to the coeliac, splenic, and left renal plexuses.

ELEVENTH OR SPINAL ACCESSORY NERVE
The spinal accessory nerve consists of two distinct parts, which are usually
known as the spinal and the accessory portions of the nerve. The former of these
(spinal portion) is a purely motor nerve which arises from the nerve-cells in the
cervical spinal cord. The accessory portion, on the other hand, arises by a series
of roots from the distal parts of both the motor and sensory accessorio-vago-
3 G 2

820
THE NERVOUS SYSTEM
glosso-pharyngeal nuclei in the medulla, and would be more properly described as
the most distal vagal roots (Obersteiner) than as a separate nerve.
The accessory portion (distal vagal roots, or bulbar accessory) consists of four
or five fasciculi which arise in a precisely similar manner to the roots of the vagus
with which they are in series. Shortly after their emergence from the medulla
they join the spinal portion and accompany the latter through the jugular foramen.
Having gained the exterior of the skull, the bulbar accessory leaves the nerve
with which it has been associated in part of its course, and joins the ganglion of
the root of the vagus; some of its fibres pass into the pharyngeal and superior
laryngeal nerves as already described.
The spinal portion arises from nerve-cells in the extreme lateral margin of the
anterior horn in the cervical portion of the spinal cord. According to some
anatomists the cells of the processus reticularis and the cells of the lateral horn
are believed to be the nucleus of this nerve. Some of the fibres run longitudinally
for a short distance and join other more direct fibres, which arch backwards and
outwards to emerge at the lateral column of the cord between the posterior nerve
roots and the attachment of the ligamentum denticulatum. The superficial origin
of the nerve is thus constituted by a row of filaments which extend from the fifth
or sixth (rarely the seventh) to the first cervical nerve. The lowest of this series
of roots is close to the ligamentum denticulatum; the highest is near to the point
of emergence of the posterior roots of the first cervical nerve. The roots unite to
form a rounded cord which courses upwards, increasing in size as it ascends, and
enters the cranial cavity by passing through the foramen magnum. Here it is
joined, for the time being, by the accessory portion, and passes with the latter, in
the form of a single trunk, through the middle compartment of the jugular
foramen. At the base of the skull it runs downwards, outwards, and backwards
between the occipital artery and the internal jugular vein, to pass under cover of
the sterno-mastoid muscle; here it pierces the deeper fibres of the muscle and
communicates with a branch derived from the second cervical nerve.
the plexus so formed the sterno-mastoid is supplied. The nerve then emerges
at the posterior border of the muscle, crosses the floor of the posterior triangle of
the neck obliquely, and passes under cover of the trapezius; on the deep surface
of that muscle the spinal accessory is joined by branches from the third and fourth
cervical nerves, and forms with them the subtrapezial plexus, from which the
trapezius is supplied.
From
TWELFTH OR HYPOGLOSSAL NERVE
The hypoglossal nerve arises from an elongated column of nerve-cells which
extends from the striæ medullares in the floor of the fourth ventricle downwards to
the level of the lower end of the olivary body. This column contains nerve-cells
of large size. It represents the neck of the anterior horn of the grey crescent in
the spinal cord, and is continued into that structure below. In its lower part the
column is placed ventro-laterally to the central canal, but, as the central canal
expands into the floor of the fourth ventricle, the grey column is displaced laterally,
and thus apparently occupies a more dorsal position. It corresponds to the area
described as the trigonum hypoglossi, and is separated from the ependyma of the
ventricle only by a thin layer of medullated fibres. From the cells embedded in
this grey column the nerve-fibres arise. These fibres pass in bundles which are
directed ventrally and outwards, internal to the olivary nucleus, between the latter
and the internal accessory olive. Finally they emerge in a row of from ten to
twelve filaments in the furrow between the olivary and pyramidal bodies, consti-
tuting the superficial origin of the hypoglossal nerve.
HYPOGLOSSAL NERVE
821
An accessory nucleus is also described which is placed ventro-laterally to the above
described (or chief) nucleus. This accessory nucleus represents a portion of the head of the
anterior horn.
Fibres pass from the inner side of the hypoglossal nucleus, and cross in the raphe from
where they ascend brainwards to establish the cortical origin of the nerve.
The filaments unite to form two fasciculi, each of which pierces the dura mater
separately at a point opposite to the anterior condyloid foramen. As these fasciculi
traverse the foramen, they unite to form a single trunk, which is placed at first on
the inner side of the pneumogastric, but then winds spirally round the ganglion of
the trunk of the latter nerve, passing behind, external to, and finally in front of
the ganglion. In this situation the hypoglossal receives two or three commu
nicating branches from the first and second cervical nerves, and some minute
twigs from the vagus and sympathetic. The hypoglossal then runs forwards and
inwards, describing a curve, the concavity of which looks downwards and outwards.
At the commencement of this part of its course it hooks round the occipital artery,
passing immediately below that vessel. It then crosses in front of the internal
and external carotid arteries, the middle constrictor of the pharynx, and the hyo-
glossus muscle, and, passing under cover of the mylo-hyoid, breaks up into its
terminal branches. As it lies on the middle constrictor the great cornu of the
hyoid bone and the lingual artery are below it and the tendon of the digastric
muscle is above it. As it passes on to the hyo-glossus it is crossed on its superficial
surface by the digastric and stylo-hyoid muscles. It is also overlapped in this
situation by the submaxillary gland.
Branches. The meningeal branch (Luschka) is given off by the hypoglossal as it
is traversing the anterior condyloid foramen, and takes a recurrent course into the
cranial cavity, where it is distributed to the dura mater. It is probably derived from
the communicating branches of the pneumogastric or from the first cervical nerve.
The remaining branches of the hypoglossal may be classified into branches of
the cervical plexus which are simply adherent for the time being to the cranial
nerve, and true hypoglossal branches; the latter are exclusively distributed to the
muscles of the tongue.
The BRANCHES DERIVED FROM THE CERVICAL PLEXUS are the descendens
hypoglossi, and the muscular twigs to the thyro-hyoid and genio-hyoid muscles.
The descendens hypoglossi parts company with the hypoglossal at the point where
the latter hooks round the occipital artery. It runs downwards and slightly inwards
on the sheath of the great vessels (occasionally within the sheath), and is joined at a
variable level by the communicantes hypoglossi from the second and third cervical
nerves, forming a loop, the ansa hypoglossi. The ansa hypoglossi may be placed at
any level from a point immediately below the occipital artery to about an inch and
a half above the sternum. A twig to the anterior belly of the omo-hyoid arises
from the descendens hypoglossi in the upper part of its course. The nerves which
supply the sterno-hyoid, sterno-thyroid, and posterior belly of the omo-hyoid are
given off by the ansa hypoglossi. Twigs from the first two nerves pass in the
muscles behind the manubrium sterni and in rare cases communicate with the
phrenic within the thorax. The nerve to the posterior belly of the omo-hyoid
runs in a loop of the cervical fascia below the central tendon of the muscle.
The nerve to the thyro-hyoid is given off near the tip of the great cornu of the
hyoid bone, and runs obliquely downwards and inwards to reach the muscle.
The nerve to the genio-hyoid arises under cover of the mylo-hyoid muscle.
The TRUE HYPOGLOSSAL BRANCHES supply the stylo-hyoid, hyo-glossus, genio-
hyo-glossus, and the intrinsic muscular fibres of the tongue.
The nerve to the stylo-hyoid is given off near the outer border of the hyo-
glossus. It pierces the stylo-glossus, and its fibres pursue a more or less recurrent
course within the muscle.


822
THE NERVOUS SYSTEM
The nerves to the hyo-glossus are several twigs which are supplied to the
muscle as the hypoglossal nerve crosses it.
The nerves to the genio-hyo-glossus arise under cover of the mylo-hyoid in
common with the terminal branches to the intrinsic muscles of the tongue. They
communicate freely with branches of the lingual, forming long loops which lie on
the hyo-glossus muscle. From these loops twigs pass into the genio-hyo-glossus
and into the muscular substance of the tongue.
SPINAL NERVES
The spinal nerves spring from the spinal cord by four long series of roots,
namely, an anterior and a posterior series on each side of the cord. These origins
correspond with the superficial origins of the cranial nerves, being the points
at which the nerve-fibres emerge from the cerebro-spinal axis. Like the cranial
nerves, the spinal nerves have also a deep origin. This is situated in the anterior
and posterior horns of the grey crescents and has been already described (page 778).
The spinal nerves also resemble the cranial nerves, inasmuch as this 'deep' origin
is only a preliminary interruption in nerve-cells or in plexuses in the grey matter,
and from the deep origin tracts of fibres pass upwards to establish a connection with
the cerebral cortex. They differ from the cranial nerves inasmuch as they arise from
the spinal cord instead of from the encephalon, in their mode of origin by an
anterior motor and posterior sensory root, and by the development, on each of the
posterior roots, of a ganglion (the spinal ganglion). Certain of the cranial nerves
resemble the spinal nerves in the two latter respects; for example, the vagus arises
from the large-celled (motor nucleus), a derivative of the anterior horn, and from
the small-celled (sensory nucleus) derived from the basal part of the posterior
horn; the roots from these two sources have, however, united before the nerve
has reached the surface of the medulla. The ganglion of the root of the vagus
and the ganglion on the sensory root of the trigeminal (Gasserian ganglion) are
clearly homologous to the ganglia on the posterior roots of the spinal nerves.
hypoglossal nerve is, in rare cases, joined by a small posterior root on which a
ganglion is developed, and, on the other hand, cases are recorded in which the
posterior root of the first spinal nerve was devoid of a ganglion.
The
The anterior roots stand out in marked contrast to the posterior roots in regard
to their function, being motor, whereas the posterior roots are sensory. They also
differ from the posterior roots in several anatomical points. The anterior roots
(with the single exception of the first) are smaller than the posterior; they arise by
four to six fasciculi, and their origins do not form a linear series, but map out a
longitudinal area of one to two millimetres in breadth on the surface of the cord.
The posterior roots are larger than the anterior, they arise by six to eight fasciculi,
are placed in a strictly linear series, and, as each root is traversing the corresponding
intervertebral foramen, it enters into a spinal ganglion, a structure with which
the motor root has no connection whatever.
The posterior roots are from one and a half to three times as large as the
anterior, the ratio being-
1 to 1.5 in the thoracic nerves.
1 to 2 in the lumbar nerves.
1 to 3 in the cervical nerves.
Course and direction. From their superficial origin, both anterior and posterior
roots proceed towards the intervertebral foramina, and unite near the outer limits
of the foramina into single trunks. The ganglia on the posterior roots are placed,
in the case of the majority of the nerves, within the foramina immediately internal
to the point of junction of the two roots. The ganglia of the first and second

SPINAL NERVES
823
cervical nerves are placed on the lamina of the atlas and axis. The ganglia of
the sacral and coccygeal nerves are placed within the spinal canal. Each spinal
ganglion is an ovoid greyish body, the long axis of which corresponds to the axis of the
nerve with which it is incorporated. It is somewhat adherent to its meningeal sheath.
The roots of the first spinal nerve ascend slightly to reach the interval between
the atlas and the occipital bone. The second and third nerves pass horizontally
outwards, the fourth passes obliquely downwards and outwards, and the remaining
nerves pass out with increasing degrees of obliquity, the intraspinal course of the
nerve-roots increasing in length as the series is followed downwards. It follows
from the above statement that the lower nerve-roots are directed almost vertically
downwards, and as the spinal cord ends at the level of the second lumbar vertebra,
while the series of intervertebral foramina is continued to the lower end of the
sacrum, the nerve-roots passing within the vertebral canal beyond the cord form a
great sheaf of fibres, the cauda equina (fig. 437). The distance of the points of
emergence (superficial origins) of certain of the nerves from the corresponding
intervertebral foramina is given in the following table. This table gives the measure-
ments made by Testut in a subject of eighteen years. The length of the spinal
cord was in this case forty-one centimetres.
Third pair of cervical nerves
Right side
Left side
mm.
mm.
18
17
Fifth
25
25
99
99
99
First
thoracic
33
32
99
99
Fifth
47
47
99
99
99
Tenth
68
68
99
99
Twelfth
. 111
110
99
99
99
First
lumbar
. 114
114
99
99
Second
. 138
134
99
99
99
Third
151
151
99
99
99
Fourth
99
35
163
164
99
Fifth
181
180
99
99
99
First
Fifth
sacral
. 188
188
99
39
280
280
99
Each spinal nerve, as it enters the intervertebral foramen, is enclosed in a strong
tubular sheath formed by the dura mater. This sheath is at first divided by a partition
into two compartments, one for the anterior and the other for the posterior root.
The septum soon disappears and allows the posterior and anterior roots to inter-
mingle their fibres. Immediately beyond the ganglion on the posterior root the
sheath thins away into the epineurium and perineurium of the nerve. The arach-
noid and pia mater also send tubular processes around the nerves; these become
continuous with the perineurium, and a connection is thus established between the
lymph spaces around the nerves and the subdural and subarachnoid spaces.
Topography. The relation of the superficial origins of the spinal nerves to the
spinous processes of the vertebræ has been investigated by Nuhn, and more recently
by Reid. In the following table, which is given by the latter anatomist, A signi-
fies the highest point of origin; B the lowest point of origin; it gives the extreme
limits of origin as observed in six subjects. For example, the origin of the sixth
thoracic nerve may extend as high as the lower border of the spine of the second
thoracic vertebra, or as low as the upper border of the spine of the fifth, but it does
not necessarily extend either as high or as low as the points indicated.

Nerves
Second cervical. (A) A little above the posterior arch of atlas.
Third
Fourth
(B) Midway between posterior arch of atlas and spine of axis.
(A) A little below posterior arch of atlas.
(B) Junction of upper two-thirds and lower third of spine of axis.
(A) Just below upper border of spine of axis.
(B) Middle of spine of third cervical vertebra.

824
THE NERVOUS SYSTEM
Nerves
Fifth
Sixth
Seventh
Eighth
cervical.
First thoracic.
Second
99
Third
Fourth
Fifth
Sixth
Seventh
Eighth
99
99
Ninth
59
Tenth
99
Eleventh
Twelfth
59
59
First lumbar
Second
Third
Fourth
Fifth
99
First
Fifth
Coccygeal
sacral
(A) Just below lower border of spine of axis.
(B) Just below lower border of spine of fourth cervical vertebra.
(A) Lower border of spine of third cervical vertebra.
(B) Lower border of spine of fifth cervical vertebra.
(A) Just below upper border of spine of fourth cervical vertebra.
(B) Just above lower border of spine of sixth cervical vertebra.
(A) Upper border of spine of fifth cervical vertebra.
(B) Upper border of spine of seventh cervical vertebra.
(A) Midway between spines of fifth cervical and sixth cervical vertebra.
(B) Junction of upper two-thirds and lower third of interval between
seventh cervical and first thoracic vertebra.
(A) Lower border of spine of sixth cervical vertebra.
(B) Just above lower border of spine of first thoracic vertebra.
(A) Just above middle of spine of seventh cervical vertebra.
(B) Lower border of spine of second thoracic vertebra.
(A) Just below upper border of spine of first thoracic vertebra.
(B) Junction of upper third and lower two-thirds of spine of third
thoracic vertebra.
(A) Upper border of spine of second thoracic vertebra.
(B) Junction of upper quarter and lower three-quarters of spine of fourth
thoracic vertebra.
(A) Lower border of spine of second thoracic vertebra.
(B) Just below upper border of spine of fifth thoracic vertebra.
(A) Junction of upper third and lower two-thirds of spine of fourth
thoracic vertebra.
(B) Just above lower border of spine of fifth thoracic vertebra.
(A) Junction of upper two-thirds and lower third of interval between
spines of fourth thoracic and fifth thoracic vertebra.
(B) Junction of upper quarter and lower three-quarters of spine of sixth
thoracic vertebra.
(A) Midway between spines of fifth thoracic and sixth thoracic vertebra.
(B) Upper border of spine of seventh thoracic vertebra.
(A) Midway between spines of sixth thoracic and seventh thoracic
vertebra.
(B) Middle of spine of eighth thoracic vertebra.
(A) Junction of upper quarter and lower three-quarters of spine of
seventh thoracic vertebra.
(B) Just above spine of ninth thoracic vertebra.
(A) Junction of upper quarter and lower three-quarters of spine of
eighth thoracic vertebra.
(B) Just below spine of ninth thoracic vertebra.
(A) Midway between spines of eighth thoracic and ninth thoracic vertebra.
(B) Lower border of spine of tenth thoracic vertebra.
(A) Middle of spine of ninth thoracic vertebra.
(B) Junction of upper third and lower two-thirds of spine of eleventh
thoracic vertebra.
(A) Middle of spine of tenth thoracic vertebra.
(B) Just below spine of eleventh thoracic vertebra.
(A) Just below spine of tenth thoracic vertebra.
(B) Junction of upper quarter and lower three-quarters of spine of
twelfth thoracic vertebra.
(A) Junction of upper third and lower two-thirds of spine of eleventh
thoracic vertebra.
(B) Middle of spine of twelfth thoracic vertebra.
(A) Just above lower border of spine of eleventh thoracic vertebra.
(B) Lower border of spine of first lumbar vertebra.
(A) Lower border of spine of first lumbar vertebra.
(B) Just below upper border of spine of second lumbar vertebra.

SPINAL NERVES
825
Classification and number.-There are thirty-one pairs of spinal nerves, viz.-
eight cervical, twelve thoracic, five lumbar, five sacral, and one coccygeal nerve. The
cervical nerves are named from the vertebræ below them; the thoracic, lumbar,
sacral and coccygeal nerves from the vertebræ above them. The first cervical or
suboccipital nerve escapes through the interval between the occipital bone and the
atlas; the eighth cervical passes through the intervertebral foramen between the
seventh cervical and first thoracic vertebræ.
General distribution.-Each spinal nerve, at its exit from the intervertebral
foramen, gives a small recurrent branch (Luschka), which receives a communicating
twig from the sympathetic, and re-enters the neural canal to be distributed to the
meninges and blood-vessels within the canal. Immediately after its exit each
nerve divides into an anterior and a posterior primary division. Both the anterior
and posterior primary divisions are mixed nerves, containing fibres derived from
both the anterior and the posterior roots.
The posterior primary divisions are, with two exceptions, smaller than the
anterior divisions. The posterior divisions of the first and second cervical nerves
are larger than the anterior; that of the second cervical nerve being three or four
times as large as the anterior division. In the regions of the great plexuses
(brachial, lumbar, and sacral) the anterior division is very much larger than the
posterior, particularly in the case of the upper sacral nerves. The posterior primary
divisions are distributed to the integument of the occiput, posterior aspect of the
neck, of the back, and of the greater part of the gluteal region. They also supply
the muscles of the posterior part of the neck and the muscles of the back, with the
exception of such of the posterior cervical and dorsal muscles as are connected with
the superior extremity, the serrati postici, and the levatores costarum.
The anterior primary divisions may be broadly stated to supply the anterior
surface of the body from the level of the chin downwards, and also the limbs. Each
anterior division is connected with the sympathetic system by rami communicantes.
The anterior divisions contrast forcibly with the posterior divisions in the great
size that they attain to in the lower cervical and lumbo-sacral regions. In these
regions they communicate with one another to form plexuses, from which a number
of branches are given off to supply the limbs.

POSTERIOR PRIMARY DIVISIONS
The posterior primary divisions of the spinal nerves are, with the exception of
the first and second cervical nerves, smaller than the anterior divisions. With the
exception of the first cervical, the fourth and fifth sacral and the coccygeal nerves,
each nerve divides shortly after its commencement into an internal and an external
branch.
CERVICAL NERVES.-The posterior divisions of the first and second cervical
require separate description. The third, fourth, and fifth cervical nerves are of
small size. They pass backwards at the outer border of the semispinalis colli,
and divide into internal and external branches.
The internal branches pass between the semispinalis colli and the complexus,
giving twigs to both these muscles and to the multifidus spinæ. They then pass
between the complexus muscle and the ligamentum nuchæ, pierce the origin of
the trapezius, and are distributed to the integument of the back of the neck. As
they enter the fascia they are directed upwards and outwards. The branch from
the third nerve is directed nearly vertically upwards, and is called the third or
smallest occipital nerve. It communicates with the great occipital nerve and
reaches the integument of the occiput.

826
THE NERVOUS SYSTEM
The external branches are distributed to the trachelo-mastoid, the cervicalis
ascendens, the transversalis colli, and to the splenius.
The internal branches of the sixth, seventh, and eighth cervical nerves pass
FIG. 452.-DISTRIBUTION OF THE POSTERIOR PRIMARY DIVISIONS OF
THE SPINAL NERVES. (Henle.)
Semi-spinalis
Multifidus spinæ
Trapezius
Rhomboideus
major
Longissimus
dorsi
Latissimus
dorsi
Ilio-costalis
-External
oblique
Gluteus
maximus
under cover of the semispinalis colli, and end in that muscle and in the adjacent
part of the multifidus spinæ. The external branches are distributed to the com-
plexus, splenius, cervicalis ascendens, and transversalis colli muscles.
The posterior primary division of the first cervical nerve passes backwards
POSTERIOR DIVISIONS OF SPINAL NERVES
827
between the posterior arch of the atlas and the vertebral artery, and traverses the
fatty tissue which occupies the triangular space bounded by the obliquus superior,
the obliquus inferior, and the rectus capitis posticus major. It gives a twig to each
of these three muscles, another twig crosses the deep surface of the rectus capitis
posticus major to reach the rectus capitis posticus minor. Another twig forms a
communicating loop with the great occipital nerve on the posterior surface of the
obliquus inferior. A branch is also furnished to the complexus. In a few cases it
gives a cutaneous twig to the back of the occiput.
The posterior division of the second cervical nerve divides into a small external
and a very large internal branch. The external branch gives a twig to the obliquus
inferior, and ends in the complexus and trachelo-mastoid muscles. The internal
branch is the great occipital nerve. It gives off communicating branches which
pass upwards and downwards, forming loops with the first and second cervical
In this manner a small plexus (posterior cervical plexus of Cruveilhier)
is formed. The great occipital nerve is then directed upwards, crossing the
triangular space described in connection with the first nerve, and being covered by
the complexus. It gives one or two twigs to the latter muscle, and then pierces it
to reach the deep surface of the trapezius. It pierces the outer border of the
trapezius immediately below the superior curved line, and divides at acute angles
into a number of branches, which ramify in the scalp. These branches communi-
cate freely with the lesser occipital nerve, and run in the subcutaneous fat between
the skin and the occipito-frontalis. In this situation they are accompanied by
branches of the occipital artery. They supply the integument which covers the
portion of the occipital bone above the superior curved line, and the posterior part
of the parietal bone.
THORACIC NERVES.-The posterior primary divisions of the thoracic nerves pass
backwards between the transverse processes of the thoracic vertebræ, and divide
into internal and external branches. The internal branches become progressively
smaller from the second to the last of the series. The external branches show a
reciprocal increase in size.
The internal branches pass to the inner side of the longissimus dorsi, giving
branches to that muscle and to the spinalis dorsi, semispinalis, multifidus spinæ,
rotatores spinæ, intertransversales, and interspinales. Large branches from the
upper six or seven nerves reach the surface by piercing the origin of the trapezius
close to the spinous processes of the vertebræ. They run outwards in the super-
ficial fascia, and supply the integument of the back, including the skin over the
inner half of the infraspinous part of the dorsum scapula and the integument over
the supraspinous fossa. The cutaneous branch of the second nerve is the largest of
the series. From the lower five or six nerves small twigs usually reach the surface
and become cutaneous.
The external branches of the upper six or seven nerves end in the accessorius
and longissimus dorsi muscles. The lower five or six, after supplying the adjacent
muscles, pierce the outer series of insertions of the longissimus dorsi, and appear
in the interval between that muscle and the accessorius. They then pierce the
latissimus dorsi, and are distributed to the integument on the lower and outer part
of the back.
LUMBAR NERVES.--The internal branches of all the lumbar nerves end in the
multifidus spinæ.
The external branches of the upper three nerves, after supplying twigs to the
adjacent muscles, pierce the posterior layer of the lumbar aponeurosis at the outer
border of the erector spinæ. The three nerves cross the crest of the ilium and
occupy different planes in the thick superficial fascia which covers the upper part
of the gluteus medius. The branch from the first nerve is comparatively small,
and occupies the most superficial plane. The second occupies an intermediate


828
THE NERVOUS SYSTEM
position. The branch from the third nerve is the largest of the three, and occupies
the deepest position; it distributes branches over the gluteus maximus as far as
the great trochanter. The three nerves communicate with one another and also
with the cutaneous branches from the posterior divisions of the two upper sacral
nerves. The external branch of the fourth lumbar nerve is of small size and ends
in the lower part of the erector spinæ. The external branch of the fifth lumbar
is distributed to the erector spinæ and communicates with the first sacral nerve.
SACRAL AND COCCYGEAL NERVES.-The posterior divisions of the upper four
sacral nerves escape from the neural canal by passing through the posterior sacral
foramina; the fifth sacral nerve passes between the sacrum and coccyx. The
coccygeal nerve escapes through the termination of the neural canal. The upper
three sacral nerves divide in the ordinary manner into internal and external
branches, the lower two sacral and the coccygeal nerves remain undivided.
The internal branches of the upper three sacral nerves are of small size, and
are distributed to the multifidus spinæ. The external branches unite with one
another and with the external branch of the last lumbar nerve to form loops on the
posterior surface of the sacrum. From these loops branches proceed to the poste-
rior surface of the great sacro-sciatic ligament, where they communicate to form a
second series of loops, from whence two or three branches are given off. These
branches pierce the gluteus maximus and come to the surface of that muscle in a
line between the posterior superior spine of the ilium and the tip of the coccyx.
They are distributed to the integument over the inner part of the gluteus maximus,
and communicate, in their course through the superficial fascia, with the posterior
branches of the lumbar nerves.
The posterior divisions of the lower two sacral and of the coccygeal nerve
unite with one another and with the posterior branch of the third sacral, and form
loops from whence twigs pass to the integument over the lower end of the coccyx.
ANTERIOR PRIMARY DIVISIONS
The anterior divisions of the spinal nerves are (with the two exceptions above
mentioned) larger than the posterior divisions. In the cervical, lumbar, sacral,
and coccygeal regions they combine to form plexuses; in the thoracic region each
nerve takes for the most part an independent course. Each anterior division
is connected by one or two rami communicantes with the gangliated cord of the
sympathetic.
CERVICAL NERVES
The upper four cervical nerves are of moderate size and unite with one another
to form the cervical plexus. The anterior division of the first nerve passes out-
wards and forwards under cover of the vertebral artery, lying in the groove on the
posterior arch of the atlas. It then bends forwards, crossing to the inner side of
the foramen in the transverse process of the atlas, and then turns downwards in
front of that process to form a loop with the second cervical nerve. In this course
.
it crosses the deep surface of the rectus capitis lateralis. The anterior division of
the second nerve runs outwards behind the superior articular process of the axis,
and passes behind and then to the outer side of the vertebral artery to reach the
interval between the scalenus medius and the rectus capitis anticus major. The
third and fourth nerves, after their exit from the intervertebral foramina, pass
behind the vertebral artery and appear in the interspace between the rectus capitis
anticus major and the scalenus medius.


CERVICAL NERVES
829
Each of the upper four cervical nerves is connected by one or two branches
with the superior cervical ganglion of the sympathetic.
The lower four cervical nerves increase rapidly in size from the fifth to the
eighth, and unite with the greater part of the first thoracic nerve to form the brachial
plexus. Each of these nerves is connected by one or two twigs to the cervical
sympathetic.
CERVICAL PLEXUS
The anterior divisions of the upper four cervical nerves unite to form the cervical
plexus in the following manner: the second and third nerves are connected by
ascending and descending branches with one another, and with the first and fourth
nerves. In this way a series of three loops is formed. The fourth nerve is also
connected with the brachial plexus by a descending twig. The branches of the
FIG. 453.-DIAGRAM OF THE CERVICAL PLEXUS.
LESSER
OCCIPITAL
TO RECTUS
CAPITIS
LATERALIS
I
GREAT AURICULAR
SUPERFICIAL CERVICAL
TO RECTUS-
CAPITIS
ANTICUS
MINOR
II
STERNO-
MASTOID
SCALENUS I
MEDIUS
LEVATOR
ANGULI
SCAPULE IV
SCALENUS
MEDIUS
LEV. ANG..
SCAPULE
TO BRACHIAL-
PLEXUS
FROM FIFTH
CERVICAL
PHRENIC
HYPOGLOSSAL
TO GENIO-
HYOID
TO THYRO-
HYOID
TO OMO-HYOID
TO
TRAPEZIUS
SUPRA-
ACROMIAL
SUPRA-
CLAVICULAR
SUPRA-
STERNAL
plexus are classified into a superficial and a deep series. The superficial series is
subdivided into ascending, transverse, and descending branches; the deep series
into external and internal branches.
SUPERFICIAL BRANCHES
Ascending branches.-1. The lesser occipital nerve is derived from the second
cervical. It passes backwards and slightly upwards under cover of the sterno-
mastoid muscle to reach the posterior border of that muscle. It then ascends, running
parallel to the posterior border of the muscle, being occasionally overlapped by it,
and passes on to the scalp, where it divides into auricular, mastoid, and occipital
branches. (a) The auricular branch runs upwards and slightly forwards to reach
the integument on the posterior and upper part of the pinna, and is distributed
there. (b) The mastoid branch is distributed to the skin covering the base of the
830
THE NERVOUS SYSTEM
mastoid process. (c) The occipital branches ramify over the occipitalis muscle, and
are distributed to the skin of the scalp; they communicate with one another and
with the great occipital nerve.
2. The great auricular nerve arises by two roots, one from the second, and the
other from the third cervical nerve. It accompanies the lesser occipital nerve as
far as the posterior border of the sterno-mastoid, and then winds round that muscle,
and crosses it obliquely. In this course it runs upwards and forwards towards
the tip of the mastoid process, and is covered by the skin, superficial fascia, and

FIG. 454.-SUPERFICIAL BRANCHES OF THE CERVICAL PLEXUS.
(After Hirschfeld and Leveillé.)
POSTERIOR
AURICULAR
NERVE
FACIAL NERVE
AURICULAR BR. OF
GREAT AURICULAR
INFRAMANDIBULAR
BRANCHES OF
GREAT
AURICULAR
GREAT OCCIPITAL
SUPERFICIAL CERVICAL
BRANCHES OF SUPERFICIAL S
CERVICAL NERVE
SUPRASTERNAL-
LESSER OCCIPITAL
GREAT AURICULAR
MASTOID BR. OR 2nd
SMALL OCCIPITAL
SPINAL ACCESSORY
TWIGS FROM THE
MASTOID BRANCH
BRANCH TO LEVATOR
ANGULI SCAPULE
SUPRA-ACROMIAL
SUPRACLAVICULAR
BRANCHES TO
STERNO-MASTOID
SUPRA CLAVICULAR
platysma. At a point about the centre of its course across the sterno-mastoid
muscle, it begins to divide into branches, which diverge from one another as they
approach the level of the mastoid process, forming mastoid, auricular, and facial
branches. (a) The mastoid branch is small, and is distributed to the integument
covering the mastoid process. (b) The auricular branches are three or four stout
twigs which cross the superficial surface of the posterior auricular branch of the

CERVICAL NERVES
831
facial, and are distributed to the skin on the back of the pinna with the exception
of its uppermost part. One or two twigs pass through fissures in the cartilage of
the ear, and are distributed to the integument on the outer surface of the lobule
and the outer surface of the lower part of the helix and antihelix. (c) The facial
branches pass upwards and forwards among the superficial lobules of the parotid
and supply the skin over that gland and immediately in front of it. In some cases
fine twigs may be traced forwards nearly to the angle of the mouth.
Transverse branch.--The superficial cervical nerve arises from the second and
third nerves, and appears at the posterior border of the sterno-mastoid, a little
below the great auricular nerve. It passes transversely across the sterno-mastoid
under cover of the integuments and platysma, and divides into a number of twigs
which spread out after the manner of a fan, and extend, as they approach the
middle line, from the chin to the sternum. The upper two or three of these twigs
unite with the inframandibular branch of the facial, and thus form loops. The
trunk of the nerve is crossed superficially by the external jugular vein as it lies on
the sterno-mastoid muscle. From the terminal branches of the nerve numerous
twigs pierce the platysma to end in the skin of the front part of the neck.
Descending branches. These are derived from the third and fourth cervical
nerves, and arise under cover of the sterno-mastoid. At their commencement they
are usually united with the muscular branches destined for the trapezius. They
become superficial at the posterior border of the sterno-mastoid, about the centre
of that muscle, and are termed suprasternal, supraclavicular, and supra-acromial
nerves. (1) The suprasternal twigs are small, and cross over the clavicular origin of
the sterno-mastoid to reach the integument over the upper part of the manubrium
sterni. (2) The supraclavicular nerves, of considerable size, cross in front of the
middle third of the clavicle under cover of the platysma, and are distributed to the
skin, covering the upper part of the pectoralis major. (3) The supra-acromial
branches cross the clavicular insertion of the trapezius and the acromion process,
and are distributed to the skin which invests the upper two-thirds of the deltoid
muscle.

DEEP BRANCHES
External branches. These consist of muscular branches, which supply the
sterno-mastoid, scalenus medius, levator anguli scapulæ, and trapezius.
1. The nerve to the sterno-mastoid arises from the second cervical nerve. It
pierces the deep surface of the sterno-mastoid, and communicates within the muscle
with the spinal accessory nerve.
2. The nerves to the scalenus medius are derived from the third and fourth
cervical close to their exit from the intervertebral foramina.
3. The nerves to the levator anguli scapulæ are derived from the third and
fourth nerves, and occasionally from the second. They pierce the superficial surface
of the levator anguli, and supply the upper three divisions of that muscle.
4. The branches to the trapezius are usually in the form of two stout twigs
which are given off by the third and fourth cervical nerves. They emerge at the
posterior border of the sterno-mastoid, and cross the posterior superior triangle of
the neck at a lower level than the spinal accessory nerve. They pass under cover
of the trapezius in company with the last-named nerve, and communicate with it
to form the subtrapezial plexus, from which the trapezius is supplied.
Internal branches.-The internal set of deep branches comprise communicating
branches and muscular branches. 1. The communicating branches pass to the
vagus and hypoglossal nerves, from the loop formed by the first and second nerves,
and to the sympathetic from all of the four nerves which enter into the cervical
plexus. The muscular branches are distributed to the rectus capitis lateralis, to
the recti capitis antici major and minor, to the longus colli, to the depressors of


832
THE NERVOUS SYSTEM
the hyoid bone (communicantes hypoglossi), and to the diaphragm (phrenic
nerve).
2. The branch to the rectus capitis lateralis is furnished to that muscle by the
first nerve as it crosses the deep surface of the muscle.
3. The nerve to the rectus capitis anticus minor is given off by the first nerve
at the upper part of the loop in front of the transverse process of the atlas.
4. The nerve to the rectus capitis anticus major is derived from twigs from
the first and second cervical nerves.
5. The nerve to the longus colli is formed by twigs from the second and third
cervical nerves.
6. The communicantes hypoglossi are given off by the second and third cervical
nerves, and run obliquely downwards and inwards in front of the great vessels of the
neck to form a loop, the ansa hypoglossi, with the so-called descendens hypoglossi.
They supply the depressor muscles of the hyoid bone. (See HYPOGLOSSAL NERVE.)
7. The PHRENIC NERVE may arise by one, two, or three roots, the strongest,
and occasionally the only, root being derived from the fourth cervical nerve. A root
from the fifth is commonly present, and is usually associated either with the nerve
to the subclavius or with the communicating branch which passes from the cervical
to the brachial plexus. A slender root from the third nerve is occasionally present.
The cervical sympathetic also furnishes a communicating twig. The phrenic nerve
passes downwards and inwards under cover of the sterno-mastoid, crossing obliquely
in front of the scalenus anticus muscle, and passes behind the subclavian vein to
enter the thorax. In this situation it crosses in front of the commencement of the
internal mammary artery, and is commonly joined at this point by a communica-
ting twig from the nerve to the subclavius muscle.
The further course of the phrenic differs on the two sides. On the right side
the nerve passes downwards, running on the outer side of the right innominate
vein, the superior vena cava, and the pericardium, between these structures and
the pleura. In its course between the pericardium and pleura it crosses in front
of the root of the lung. It then pierces the diaphragm immediately on the
left side of the opening for the vena cava inferior, and is distributed to the
diaphragm, the branches entering the muscle on its lower surface. On the
left side the phrenic nerve passes on to the left side of the so-called transverse
portion of the aortic arch between the latter and the pleura, and in front of
the inferior cervical cardiac branch of the vagus. It then runs downwards
between the pericardium and the pleura in front of the root of the lung,
taking a longer course than on the right side in consequence of the inclina-
tion of the heart to the left side, and also on account of the lower level of the left
cupola of the diaphragm. It pierces the diaphragm immediately to the left of the
attachment of the pericardium to that muscle, and is distributed to its abdominal
surface in a similar manner to the nerve on the right side.
Branches.-Minute twigs are supplied (a) to the pleura; and (b) to the peri-
cardium. On the right side the nerve.communicates with the diaphragmatic plexus
of the sympathetic, forming a small ganglion (ganglion diaphragmaticum).
BRACHIAL PLEXUS
The BRACHIAL PLEXUS is formed by the anterior primary divisions of the four
lower cervical nerves, the greater part of the first thoracic nerve, and is usually joined
by small communicating twigs from the fourth cervical and second thoracic nerves.
The four lower cervical nerves emerge in the interval between the anterior and
middle scaleni muscles. The first thoracic nerve, after traversing the intervertebral
foramen between the first and second thoracic vertebræ, appears in the first inter-
costal space and, after giving off the small first intercostal nerve, crosses the inner

BRACHIAL PLEXUS
833
margin and upper surface of the first rib obliquely, and joins the eighth cervical
nerve.
The brachial plexus is divisible into four distinct stages. In the first stage all
the component nerves are separate from each other. In the second stage the
nerves unite with one another to form trunks. In the third stage the trunks
divide into anterior and posterior divisions. In the fourth stage the six divisions
become collected into three rounded bundles, which are termed cords.
The fifth and sixth, and usually a communicating twig from the fourth, cervical
nerves unite to form the upper trunk; the seventh remains independent and forms
the middle trunk; the eighth cervical and first thoracic, with occasionally a communi-
cating twig from the second thoracic, unite to form the lower trunk. Each of these
trunks divides into an anterior and a posterior division. The anterior and posterior
divisions of the upper and middle trunks are about equal in size. The anterior
division of the lower trunk is very much larger than the posterior division. The
FIG. 455.
FIFTH
CERVICAL
SIXTH
CERVICAL
DIAGRAM OF THE BRACHIAL PLEXUS.
The posterior cord of the plexus is darkly shaded.
FROM FOURTH CERVICAL
RHOMBOID NERVE
TO PHRENIC
SEVENTH
CERVICAL
TO SCALENI &
LONGUS COLLI
EIGHTH
CERVICAL
POSTERIOR
THORACIC.
FIRST
THORACIC
FIRST
INTERCOSTAL
SECOND
THORACIC
SECOND
INTERCOSTAL
THIRD
THORACIC
THIRD
INTERCOSTAL
NERVE TO SUBCLAVIUS
SUPRASCAPULAR
EXTERNAL ANTERIOR THORACIC
OUTER CORD OF PLEXUS
CIRCUMFLEX
MUSCULO-CUTANEOUS
MUSCULO-SPIRAL
INNER CORD OF PLEXUS
LONG
SUBSCAPULAR
MEDIAN
ULNAR
INTERNAL
CUTANEOUS
NERVE OF
WRISBERG
INTERCOSTO-HUMERAL
LATERAL CUTANEOUS
three posterior divisions unite to form the posterior cord.
of the upper and middle trunks join to form the outer cord.
of the lower trunk is continued into the inner cord.
The anterior divisions
The anterior division
The first stage of the plexus is situated between the anterior and middle scaleni
muscles, and at the outer border of the former muscle. The second stage is placed
in the posterior inferior triangle of the neck, the lower trunk of the plexus being
behind the third stage of the subclavian artery and the upper and middle trunks
above and on a plane posterior to that vessel. When a posterior scapular artery
arises from the third stage of the subclavian, it passes backwards between the
trunks of the plexus. In its third stage the plexus lies under cover of the clavicle and
subclavius muscle, and is placed above, external, and on a plane posterior to the
axillary artery. In its fourth stage the plexus is situated under cover of the pectoral
muscles, and the cords surround the second stage of the axillary artery, occupying
3 H

834
THE NERVOUS SYSTEM
the positions indicated by their names, the external cord being in contact with the
outer side of the artery, the internal cord on the inner side, and the posterior cord
behind the vessel. A little external to the outer border of the pectoralis minor, the
plexus terminates by dividing into large nerves, which surround the third stage of
the axillary artery.
The branches of the brachial plexus are classified into branches which arise
above the clavicle, and branches which are given off below that bone. The branches
which arise below the clavicle may be conveniently subdivided into short branches
which end in the axilla, and long branches which arise from the terminations of the
three cords and are destined to supply the shoulder, arm, forearm, and hand.
BRANCHES GIVEN OFF ABOVE THE CLAVICLE
These are all muscular branches, and comprise the following nerves:-(1) Supra-
scapular; (2) rhomboid; (3) posterior thoracic; (4) communicating to the phrenic;
nerves to (5) the subclavius, (6) scaleni, and (7) longus colli.
(1) The suprascapular nerve arises from the upper trunk of the plexus, and
therefore contains fibres derived from the fifth and sixth, and in some cases from the
fourth, cervical nerves. It runs downwards and outwards below the posterior belly
of the omo-hyoid muscle, and passes under cover of the trapezius to reach the supra-
scapular notch; here it crosses the suprascapular artery, and takes a lower position
than that vessel. It then passes through the suprascapular notch beneath the
transverse ligament, and, after furnishing a twig to the shoulder joint, divides into
a supraspinous and an infraspinous branch. The supraspinous branch inclines
inwards and ends in the supraspinatus muscle. The infraspinous branch passes
through the great scapular notch under cover of the spino-glenoid ligament, and
terminates in the infraspinatus muscle.
(2) The nerve to the rhomboids arises from the fifth cervical nerve shortly after
its exit from the intervertebral foramen. It arises in common with the upper root of
the posterior thoracic nerve, and passes backwards and outwards through the fibres of
the scalenus medius. It then usually divides in a plexiform manner into several
branches, the strongest of which passes below the levator anguli scapula, while the
others traverse the lowest division of that muscle and supply it with one or more
twigs. In the cellular interval between the levator and the rhomboideus minor,
the twigs reunite to form one nerve, which passes to the deep surface of the two
rhomboid muscles and supplies them.
(3) The posterior thoracic nerve (external respiratory of Bell) arises, by three
roots, from the fifth, sixth, and seventh cervical nerves. The upper two roots traverse
the substance of the scalenus medius; the root from the seventh passes in front of
that muscle. Twigs are furnished to the superior portion of the serratus magnus
by the upper two roots; lower down they unite and are subsequently joined by the
root from the seventh. The nerve now passes downwards behind the brachial
plexus and the first stage of the axillary artery, and runs along the axillary surface
of the serratus magnus, supplying twigs to each of the digitations of that muscle.
(4) The communicating twig to the phrenic arises from the fifth nerve close to the
point where the latter nerve receives the communicating twig from the cervical plexus.
(5) The nerve to the subclavius is a small twig which arises from the fifth nerve
or from the upper trunk of the plexus. Its fibres are derived from the fifth or in
some cases from the fourth cervical nerve through the communicating twig from
the cervical plexus. It runs downwards in front of the third stage of the subclavian
artery and, after giving off a communicating branch to the phrenic, pierces the costo-
coracoid membrane, and enters the subclavius at the lower border of that muscle.
Variety. In rare cases the entire phrenic nerve may pass via the nerve to the subclavius
in front of the third stage of the subclavian artery.
BRANCHES OF BRACHIAL PLEXUS
835
(6) The scaleni and (7) longus colli are supplied by twigs which arise from the
lower three cervical nerves immediately after
their exit from the intervertebral
foramina.
BRANCHES GIVEN OFF BELOW THE CLAVICLE
The AXILLARY or SHORT BRANCHES are (1) the external and (2) internal
anterior thoracic, and (3) the three subscapular nerves.
(1) The external anterior thoracic nerve arises from the outer cord of the
plexus, and, after communicating with the internal anterior thoracic, ends in
branches which supply the pectoralis major.
(2) The internal anterior thoracic nerve arises from the inner cord and passes
forwards between the first stage of the axillary artery and the axillary vein. It
gives branches to the pectoralis minor, some of which pass through the latter
muscle and end in the great pectoral. The nerve then unites with a branch from
the external anterior thoracic, and forms a loop which is placed in front of the first
stage of the axillary artery. From this loop additional branches are furnished to
the greater pectoral muscle.
(3) The subscapular nerves are branches of the posterior cord. They are three
in number, are distinguished as upper, middle, and lower, and are distributed to the
subscapularis, latissimus dorsi, and teres major muscles.
(a) The upper or short subscapular nerve is distributed exclusively to the sub-
scapularis muscle. It is occasionally double.
(b) The middle or long subscapular nerve accompanies the subscapular artery
along the axillary margin of the subscapularis muscle and ends in the latissimus dorsi.
(c) The lower subscapular nerve is distributed to the teres major and furnishes
one or two twigs to the subscapularis. These twigs enter the subscapularis near
the axillary margin of that muscle.
TERMINAL OR LONG BRANCHES.-These are given off as follows: from the outer
cord, the musculo-cutaneous and the outer head of the median; from the inner
cord, the inner head of the median, the ulnar, the internal cutaneous, and the lesser
internal cutaneous; from the posterior cord, the musculo-spiral and the circumflex
nerves. The circumflex, lesser internal cutaneous, internal cutaneous, and musculo-
cutaneous are more proximal in their distribution than the median, ulnar, and
musculo-spiral, and may therefore be first described.
(1) The circumflex nerve is a branch of the posterior cord, and is composed of
fibres derived from the fifth, sixth, seventh, and eighth cervical nerves. It accom-
panies the posterior circumflex artery through the quadrilateral space bounded by
the teres major, long head of triceps and subscapularis muscles and by the surgical
neck of the humerus, and divides into a smaller posterior and a larger anterior
division. Previous to its division it furnishes an articular twig to the shoulder
joint. This twig pierces the inferior part of the capsular ligament.
(a) The anterior division accompanies the posterior circumflex artery around the
neck of the humerus, and gives off a number of stout twigs which enter the deltoid
muscle. A few fine filaments pierce the deltoid and end in the integument which
covers the middle third of that muscle.
(b) The posterior division divides into a cutaneous and a muscular branch. The
cutaneous branch supplies the skin covering the lower third of the deltoid and
a small area of integument below the insertion of that muscle. The muscular
branch is distributed to the teres minor; it swells out into an ovoid or fusiform
reddish gangliform enlargement before perforating the muscle.
(2) The lesser internal cutaneous nerve, or nerve of Wrisberg, arises from the
inner cord of the brachial plexus, and is formed of fibres derived from the eighth
cervical and first thoracic nerves or from the first thoracic nerve alone. It runs down-
wards on the inner side of the axillary vein, being separated by that vessel from the


3H 2

836
THE NERVOUS SYSTEM
ulnar nerve.
It passes downwards with a slight inclination backwards under cover
of the deep fascia on the inner side of the arm. Near the bend of the elbow it turns
somewhat sharply backwards to supply the integument which covers the olecranon
process. As it traverses the axilla, the nerve of Wrisberg communicates with the
intercosto-humeral nerve, forming one or sometimes two loops. In its course
down the arm it gives a few fine twigs to the integument.
(3) The internal cutaneous is a branch of the inner cord, its fibres being ulti-
mately derived from the eighth cervical and first thoracic nerves. At its origin it lies
on the inner side of the axillary artery, but it soon passes on to the anterior surface
of that vessel, and bears the same relation to the brachial artery in the upper two-
FIG. 456.-DISTRIBUTION OF CUTANEOUS NERVES ON THE ANTERIOR AND POSTERIOR
ASPECTS OF THE SUPERIOR EXTREMITY.
INTERNAL
CUTANEOUS OF
MUSCULO-SPIRAL
INTERNAL
CUTANEOUS
PALMAR
CUTANEOUS OF
MEDIAN
PALMAR
SUPRA-ACROMIAL
CIRCUMFLEX
INTERCOSTO-
HUMERAL
TWIG OF
INTERNAL
CUTANEOUS
EXTERNAL
CUTANEOUS OF
MUSCULO-SPIRAL
CIRCUMFLEX-
SUPRA-
ACROMIAL
INTERNAL
CUTANEOUS OF
MUSCULO-SPIRAL
INTERCOSTO-
HUMERAL
NERVE OF
WRISBERG
MUSCULO-
CUTANEOUS
EXTERNAL
CUTANEOUS OF
MUSCULO-SPIRAL
INTERNAL
CUTANEOUS
CUTANEOUS OF
ULNAR
PALMAR
CUTANEOUS
OF RADIAL
MUSCULO-
CUTANEOUS
RADIAL
ULNAR
thirds of the arm. It then pierces the deep fascia in company with the basilic vein,
and divides into an anterior and a posterior branch. Previous to its division it gives
off a twig which pierces the deep fascia, and supplies the integument of the upper
and inner part of the arm. (a) The anterior branch is larger than the posterior,
and divides at acute angles into several twigs, some of which pass in front of and
some behind the median basilic vein, and then run down the forearm to supply the
integuments covering its anterior and internal aspect as far as the wrist. (b) The
posterior branch passes downwards and backwards in front of the internal condyle
of the humerus, and divides into branches which supply the skin on the postero-
external aspect of the forearm.

BRANCHES OF BRACHIAL PLEXUS
837
(4) The musculo-cutaneous nerve is a branch of the posterior cord of the brachial
plexus. It is composed of fibres which are derived from the fifth, sixth, and seventh
cervical nerves. It is placed at first close to the outer side of the brachial artery,
but soon leaves that vessel and pierces the coraco-brachialis muscle in a direction
obliquely downwards and outwards. Continuing this oblique direction, it passes
between the biceps and brachialis anticus muscles, and becomes superficial at the
outer border of the former muscle, a little above the bend of the elbow. It then
passes on the deep surface of the median cephalic vein, and divides into an anterior
and a posterior branch. Previous to its division, the musculo-cutaneous nerve
FIG. 457.-A DISSECTION SHOWING THE ARRANGEMENT OF THE NERVES IN FRONT
OF THE ELBOW.
(From a mounted specimen in the Anatomical Department of Trinity College, Dublin.)
POSTERIOR BRANCH
OF INTERNAL
CUTANEOUS
ANTERIOR BRANCH
OF INTERNAL
CUTANEOUS
NERVE TO
SUPINATOR
LONGUS
RADIAL
BRANCH TO
PRONATOR TERES
Bicipital fascia
POSTERIOR
INTEROSSEOUS
MUSCULO-
CUTANEOUS
MEDIAN NERVE
supplies three muscles, viz. the coraco-brachialis, the biceps, and the brachialis
anticus. The nerves to the coraco-brachialis are two or three twigs which are
given off from the nerve close to its origin, and before it has traversed the muscle.
The nerves to the biceps and brachialis anticus muscles arise from the musculo-
cutaneous nerve as it is passing between these muscles. There is a separate
branch for each head of the biceps. The posterior terminal branch is small, and
is directed downwards and backwards in front of the external condyle of the
humerus to be distributed to the skin on the outer and posterior aspect of the
forearm as low as the wrist. The anterior branch runs downwards on the outer
and anterior part of the forearm, supplying the integument of that region, and,

838
THE NERVOUS SYSTEM
having communicated near the wrist with the radial nerve, terminates in the skin
covering the middle part of the thenar eminence.
(5) The median nerve is formed by fibres derived from the fifth, sixth, seventh,
and eighth cervical and first thoracic nerves. It arises by two heads, one from the
outer, and one from the inner cord. The inner head crosses obliquely in front of
the third stage of the axillary artery, and joins the outer head on the external side
of that vessel. The median nerve runs almost vertically down the arm under cover of
the skin and fascia, and is partially overlapped by the biceps. In the upper part
of the arm it is placed on the outer side of the brachial artery. About the middle
of the arm it crosses in front of that vessel, and then runs down on the inner
side of the artery to the bend of the elbow. It then passes between the two heads of
the pronator radii teres, and is separated from the ulnar artery in this situation by
the deep head of the muscle. It then runs vertically downwards in the middle line
of the forearm between the flexor sublimis and flexor profundus digitorum; in this
part of its course it is accompanied by a companion artery, the comes nervi mediani.
At the upper border of the annular ligament it is placed between the tendons of the
flexor carpi radialis and palmaris longus muscles, and somewhat overlapped by the
tendons of the flexor sublimis. It then passes under cover of the anterior annular
ligament on the superficial surface of the flexor tendons, and, at the lower border
of the ligament, bifurcates into two terminal divisions, an inner and an outer.
Branches. The median nerve does not supply any part of the upper arm.
In front of the elbow joint it furnishes one or two filaments to the articulation.
In the forearm it supplies all the superficial anterior muscles (with the exception
of the flexor carpi ulnaris) directly from its trunk, and supplies the deep muscles
(with the exception of the inner half of the flexor profundus) by its anterior
interosseous branch. In the hand it supplies the group of short muscles of the
thumb (with the exception of those which are placed on the ulnar side of the
tendon of the flexor longus pollicis), the two outer lumbricales, the integument
covering the central part of the palm and inner part of the thenar eminence, and
the palmar aspect of the thumb, index, middle, and radial half of the ring fingers.
It also sends twigs to the dorsal aspect of these digits.
(a) The nerve to the pronator radii teres arises a little above the bend of the
elbow, and pierces the outer border of that muscle.
(b) The nerves to the flexor carpi radialis, palmaris longus, and flexor sublimis
digitorum arise a little lower down, and pierce the pronator-flexor mass of muscles,
to end in the respective members of the group for which they are destined.
(c) The anterior interosseous nerve arises from the median at the level of the
bicipital tubercle of the radius, and runs downwards on the interosseous membrane
accompanied by the anterior interosseous artery. It passes under cover of the
pronator quadratus, and pierces the deep surface of that muscle. The anterior
interosseous nerve also furnishes a twig to the front of the wrist joint and supplies
the flexor profundus digitorum and the flexor longus pollicis. The nerve to the
former muscle arises from the posterior interosseous near its commencement and
supplies the outer two divisions of the muscle, and communicates within its
substance with twigs derived from the ulnar nerve.
(d) The palmar cutaneous branch arises immediately above the anterior annular
ligament and passes between the tendons of the flexor carpi radialis and the
palmaris longus. It then crosses the superficial surface of the annular ligament, is
distributed to the integument and fascia on the central depressed surface of the
palm, and supplies a few twigs to the inner border of the thenar eminence; these
twigs communicate with the musculo-cutaneous and radial nerves.
(e) The branch to the muscles of the thumb arises at the lower border of the
annular ligament, and, winding round that ligament, divides into twigs to supply
the abductor, the opponens, and the outer head of the flexor brevis pollicis.
MEDIAN AND ULNAR NERVES
839
(f) The external terminal division divides into two branches. The outer branch
passes obliquely across the long flexor tendon of the thumb, and runs along the
radial border of the thumb as far as its extremity. It gives numerous branches to
the pulp of the thumb, and a strong twig which passes on to the dorsum to supply
the matrix of the nail. The inner branch, after running a course varying from
an eighth to a half an inch, divides into two digital collateral branches. The outer
collateral branch supplies the ulnar side of the volar aspect of the thumb, and
gives off a twig to the matrix of the thumb nail. The inner collateral branch is
distributed in a similar manner to the radial side of the index finger. It gives off a
twig to supply the first lumbrical muscle.
(g) The internal terminal division divides into an outer and an inner branch.
The outer branch gives a twig to supply the second lumbrical muscle, and divides
a little above the metacarpo-phalangeal articulation into collateral branches, which
supply the adjacent sides of the index and middle fingers, and also give twigs to
the dorsum of these digits. These dorsal twigs will be more particularly described
later on (page 843). The inner branch communicates with the ulnar nerve and
divides to supply the adjacent sides of the middle and ring fingers.
FIG. 458.-SUPERFICIAL NERVES OF THE PALM. (Ellis.)

BRANCH TO
MUSCLES OF
THUMB
MEDIAN NERVE-
ULNAR NERVE
COMMUNICATION
BETWEEN MEDIAN
AND ULNAR
COLLATERAL
BRANCHES OF
MEDIAN
COLLATERAL BRANCHES
OF ULNAR
As the branches of the median nerve pass downwards in the palm of the hand, they
cross the deep or posterior surface of the superficial palmar arch. This relation to
the arteries is reversed in the fingers, where the digital arteries are placed behind the
nerves. As each digital nerve pursues its course along the margin of the corresponding
finger, it gives off twigs to the dorsum of the finger, particularly stout twigs passing to
supply the matrix of the nail. Each nerve terminates in branches to the pulp of the
finger, and on these terminal branches as well as on the more proximal twigs to the volar
aspect of the fingers, ovoid bodies, about the size of millet seeds, are developed. These
bodies are called Pacinian corpuscles, and are one of the forms of sensory nerve-terminations.

840
THE NERVOUS SYSTEM
(6) The ulnar nerve is the largest branch of the inner cord of the brachial plexus,
and is derived from the eighth cervical and first thoracic nerves. It runs downwards
between the axillary artery and the vein, and preserves the same relation to the
brachial artery for the upper third of the arm. It then diverges from the brachial
artery at an acute angle, and accompanies the inferior profunda artery to the
interval between the internal condyle of the humerus and the olecranon process of
the ulna. In this course it is placed under cover of the deep fascia, and pierces
the internal intermuscular septum. It then passes between the two heads of the
flexor carpi ulnaris, and runs downwards under cover of that muscle, between it
and the flexor profunda digitorum, to reach the wrist. At the junction of the
upper and middle thirds of the forearm it is joined at an acute angle by the ulnar
artery, and runs parallel to the inner side of that vessel in the middle and lower
two-thirds of the forearm. It enters the hand by crossing the superficial surface
of the anterior annular ligament close to the radial border of the pisiform bone,
and terminates by bifurcating into a superficial and a deep division.
Branches.-The ulnar resembles the medial nerve in not furnishing any branches
to the upper arm. As it passes between the olecranon process and the internal
condyle, it gives off two or three fine filaments to the elbow joint. In the forearm
it supplies the flexor carpi ulnaris and the inner portion of the flexor profundus
digitorum, and gives off the palmar cutaneous branch. In the hand it supplies
the integument of the hypothenar eminence, the little finger and half of the ring
finger and part of the dorsum; it also gives twigs to the palm. It also supplies
the short intrinsic muscles of the hand with the exception of the abductor, the
opponens, the outer head of the flexor brevis pollicis, and the two outer lumbricales.
(a) The nerves to the flexor carpi ulnaris and to the inner two divisions of the
flexor profundus digitorum arise from the ulnar in the upper third of the forearm.
(b) The palmar cutaneous arises at the junction of the middle and lower thirds
of the forearm, and runs downwards in front of the ulnar artery, and is conducted
by the vessel into the palm. It furnishes some filaments to the vessel, and ends
in the integument covering the central depressed surface of the palm.
(c) The dorsal or posterior branch arises about two inches above the wrist joint,
and passes backwards under cover of the flexor carpi ulnaris to reach the dorsal
aspect of the wrist. It crosses superficial to the tendon of the extensor carpi
ulnaris immediately below the lower end of the ulna, and, after giving off twigs to
supply the skin of the dorsum of the hand, divides into three branches, namely:
a branch to the inner border of the little finger; a branch which divides to supply
the contiguous borders of the ring and little fingers, and a branch which communi-
cates with the radial and participates in the supply of the adjacent borders of the
ring and middle fingers.
(d) The superficial terminal branch of the ulnar nerve gives off a branch to
supply the palmaris brevis muscle, and several twigs, which are distributed to the
skin which covers the hypothenar eminence, and then divides into two branches, an
inner and an outer. The inner branch is distributed to the inner side of the little
finger on its volar aspect. The outer branch communicates with the median nerve,
and then divides to supply the contiguous margins of the ring and little finger.
The distribution of these branches to the fingers resembles that of the digital
branches of the median nerve, which has been already described.
(e) The deep branch of the ulnar nerve accompanies the deep branch of the
ulnar artery into the interval between the abductor and flexor brevis minimi digiti
muscles, and then passes through the fibres of the opponens minimi digiti to reach
the deep surface of the flexor tendons. It supplies the abductor, flexor brevis,
and opponens minimi digiti, the two inner lumbricales, all the interossei, the
adductor, and the inner head of the flexor brevis pollicis. Occasionally it also
gives a twig to the outer head of the flexor brevis pollicis.

RADIAL NERVE
841
(7) The musculo-spiral nerve is the largest branch of the brachial plexus. It
arises from the posterior cord, and contains fibres derived from the fifth, sixth,
seventh, and eighth cervical nerves. It is placed at first behind the third stage of
the axillary artery; lower down it has a similar relation to the upper part of the
brachial artery. It soon leaves the latter vessel and accompanies the superior
profunda artery into the interval between the inner and outer heads of the triceps.
Having followed the spiral groove around the humerus, it pierces the external inter-
muscular septum and runs downwards in the interval between the supinator longus
and the brachialis anticus muscles. A little above the bend of the elbow it termi-
nates by dividing into the radial and the posterior interosseous nerves.
Branches. The musculo-spiral nerve gives off three cutaneous branches, one
internal and two external, and supplies the following muscles: triceps, anconeus,
brachialis anticus in part, supinator longus, and extensor carpi radialis longior.
(a) The internal cutaneous branch arises within the axilla, usually in common
with the branch to the long head of the triceps. It crosses the tendon of the
latissimus dorsi muscle and passes on to the back of the arm to supply a strip of
integument extending nearly down to the elbow, and placed between the areas of
distribution of the circumflex and intercosto-humeral nerves.
(b) The external cutaneous branches are distinguished as upper and lower. The
upper branch, much the smaller, pierces the deep fascia in the line of the external
intermuscular septum, and is distributed to the skin over the lower part of the
biceps muscle. The lower branch is of considerable size. It pierces the deep fascia
a little below the upper branch, and runs on the supinator longus in front of the
external condyle of the humerus. It then inclines backwards and supplies the
integument on the back of the forearm as far as the wrist.
(c) A nerve is furnished to each of the three heads of the triceps. The nerve to
the long head arises within the axilla. The nerves to the outer and inner heads
arise as the nerve is traversing the spiral groove. A separate branch, the ulnar
collateral of Krause, accompanies the ulnar nerve for some distance, and ends in
the lower part of the inner head of the triceps.
(d) Muscular branches. The nerve to the anconeus arises in common with
the nerve to the inner head of the triceps, and runs down in the fibres of the latter
muscle towards the interval between the olecranon process and the external condyle,
where it ends in the anconeus. In its course through the triceps it furnishes a
number of fine filaments to that muscle.
The nerves to the brachialis anticus, supinator longus, and extensor carpi
radialis longior arise in the interval between the first and two last named muscles.
(e) The posterior interosseous nerve passes downwards in the interval between
the brachialis anticus and the extensor carpi radialis longior, and, having given off
a branch to supply the extensor carpi radialis brevior, it runs downwards and back-
wards through the substance of the supinator brevis, and enters the cellular interval
between the superficial and deep layers of muscles at the back of the forearm.
Having given off twigs to supply these muscles, it passes on to the interosseous
membrane at the lower third of the forearm, and passes under cover of the tendons
of the extensor communis digitorum to reach the back of the wrist, where it swells
into a gangliform enlargement, from which twigs are given off to supply the carpal
articulations. The muscles supplied by the posterior interosseous nerve are the
extensor carpi radialis brevior, the supinator brevis, the extensor communis
digitorum, extensor minimi digiti, extensor carpi ulnaris, the three extensor muscles
of the thumb, and the extensor indicis. The supinator brevis receives two twigs,
one of which is given off before the nerve pierces the muscle, and the other while
it is traversing the muscular substance.
(f) The radial nerve is somewhat smaller than the posterior interosseous, and
is a purely cutaneous nerve. It runs downwards under cover of the supinator longus,

842
THE NERVOUS SYSTEM
and, approaching the radial artery at an acute angle, runs parallel to the outer side
of that vessel in the middle third of the forearm. It then parts company with the
artery by bending backwards on the deep surface of the tendon of the supinator
longus. It then pierces the deep fascia and is directed towards the back of the
wrist, where it divides into its terminal branches. One of these, the palmar
cutaneous of the radial nerve, supplies the outer part of the thenar eminence; two
others supply the dorsum of the thumb, a fourth branch runs along the radial side
of the index finger, a fifth divides to supply the adjacent side of the index and
middle fingers, and a sixth branch communicates with the dorsal branch of the
ulnar nerve to supply the adjacent side of the middle and ring fingers.
FIG. 459.-A DISSECTION OF THE CUTANEOUS NERVES ON THE DORSAL ASPECT
OF THE HAND AND FINGERS. (H. St. J. B.)
The branches of the median nerve are shown in black.
DORSAL BRANCH
OF ULNAR
BRANCH OF MUSCULO-SPIRAL
RADIAL NERVE
BRANCH OF
MEDIAN
NERVE
Nerve-supply of the dorsal integument to the hand. It will be seen, by the foregoing
description of the radial and ulnar nerves, that the thumb, index, and half the middle finger
are supplied by the radial; the little and half the ring finger by the ulnar; and the adjacent
sides of the ring and middle fingers by both radial and ulnar nerves. The distance to
which these nerves extend on the digits is somewhat variable, but the following is the
INTERCOSTAL NERVES
843
average condition :-The radial nerve extends to the base of the thumb nail, to the distal
interphalangeal joint of the index, and not quite to the proximal interphalangeal joint
of the middle finger, and sends a fine twig in some cases to the skin covering the meta-
phalangeal articulation of the ring finger. The ulnar nerve extends to the nail of the little
finger, to the distal interphalangeal joint of the ring, and in some cases to the integument
covering the proximal interphalangeal joint of the middle, and the metacarpo-phalangeal
articulation of the index finger. The distal parts of the dorsum of the fingers are supplied
by twigs from the palmar collateral branches of the median and ulnar, almost the whole
of the middle finger being supplied in this way, and the other digits to a less degree. The
matrix of the thumb nail is supplied by twigs from the palmar branches of the median.
A considerable part of the dorsum of the hand is usually supplied by twigs from both the
radial and the ulnar nerves, as these nerves overlap one another in their distribution
(fig. 459). Occasionally two other nerves, the musculo-cutaneous and the lower external
cutaneous branch of the musculo-spiral, take part in the supply of the back of the hand.

THORACIC NERVES
The smaller part of the first thoracic nerve and the second to the eleventh
thoracic nerves follow the contour of the body wall in the intervals between the
ribs, and are therefore termed intercostal nerves. The twelfth thoracic nerve
pursues a parallel course to the others, below the twelfth rib. Each of the
intercostal nerves is accompanied by an intercostal artery and vein. These vessels
are placed, immediately above the nerve, in the groove at the lower border of the rib.
The twelfth thoracic nerve is accompanied by the first lumbar artery. Each
thoracic nerve is joined, near the head of the rib, by two rami communicantes from
the gangliated cord of the sympathetic. The first and last thoracic nerves require
separate description. The remaining ten nerves fall naturally into an upper and a
lower group. The members of the upper group (the second to the sixth) run
between the ribs as far as the margin of the sternum. The members of the lower
group (seventh to eleventh nerves) lie for a part of their course between the layers
of the abdominal wall, the extent of the abdominal distribution increasing from the
highest to the lowest member of the series.
A. First thoracic nerve. The greater part of the first thoracic nerve crosses the
neck of the first rib to join the brachial plexus, as already described. The smaller
part, about one-fifth of the entire nerve, runs for about two inches in contact with
the under surface of the first rib between the bone and the pleura, and then enters
the cellular interval between the external and internal intercostal muscles. For the
remainder of its course it corresponds to the upper intercostal nerves in its distri-
bution, but it does not usually give a lateral or an anterior cutaneous branch.
Variety. In some cases a lateral cutaneous nerve arises from the first intercostal nerve.
It may be of small size, but is sometimes as large as an ordinary intercosto-humeral
It communicates with the intercosto-humeral nerve and with the nerve of

nerve.
Wrisberg.
B. Upper intercostal nerves.-The second, third, fourth, fifth, and sixth inter-
costal nerves, after receiving communications from the sympathetic, are directed
outwards in the intercostal spaces in front of the posterior intercostal membrane,
between that membrane and the pleura. They then enter the interval between the
external and internal intercostal muscles, and follow the curve of the thoracic wall
between these muscles as far as the mid-axillary line, and then, taking a deeper
position, they run through the fibres of the internal intercostals as far as the junction
of the bony parts of the ribs with their cartilages. They then pass forwards on the
deep surface of the internal intercostal muscles, lying on the pleura and on the slips of
the triangularis sterni, and cross in front of the internal mammary vessels. Lastly,
they bend forwards and pierce the internal intercostals and pectoralis major, and

844
THE NERVOUS SYSTEM
FIG. 460.-CUTANEOUS NERVES OF THE THORAX AND ABDOMEN, VIEWED FROM THE
SIDE. (After Henle.)
SUPRACLAVICULAR BRANCH-
OF CERVICAL PLEXUS
Pectoralis minor.
Sheath of rectus.
ANTERIOR
CUTANEOUS OF
LAST THORACIC
ILIO-
HYPOGASTRIC
ILIO-INGUINAL
Pectoralis major-
-BRACHIAL
PLEXUS
INTERCOSTO
HUMERAL
Latissimus dorsi
Serratus magnus
External oblique
LATERAL CUTANEOUS OF
LAST THORACIC NERVE

INTERCOSTAL NERVES
845
terminate as the anterior cutaneous nerves of the thorax. In this course they give
off muscular branches to the levatores costarum, serratus posticus superior, external
and internal intercostals, and triangularis sterni. Each nerve also gives off two
cutaneous branches-namely, the lateral and anterior cutaneous nerves of the thorax.
The lateral cutaneous nerves of the thorax pierce the external intercostal
muscles, and divide into anterior and posterior branches. These branches pass
between the digitations of the serratus magnus, and are separated by an interval
of about half an inch, when they appear on the superficial surface of that muscle.
The anterior branches run forwards, cross the lower border of the great pectoral,
and supply the integuments which cover the lower and outer portion of that muscle,
and give twigs to the mammary gland. They decrease progressively in size from
the sixth to the third. In the case of the second lateral cutaneous nerve, the
anterior branch is usually wanting. The posterior branches turn backwards, and
supply the skin covering the outer part of the latissimus dorsi and the inferior angle
of the scapula. The lateral cutaneous branches of the second and third intercostal
nerves are larger than the others, and require separate notice. The lateral cutaneous
branch of the second intercostal nerve is called the intercosto-humeral nerve. It
passes outwards across the axillary space, and crosses the tendon of the latissimus
dorsi to reach the arm. It is distributed to the integument of the inner and
posterior part of the arm in its upper two-thirds. Within the axilla it communi-
cates with the lesser internal cutaneous nerve of the brachial plexus, and with the
lateral cutaneous branch of the third intercostal. The lateral cutaneous branch
of the third intercostal divides into a small anterior and a large posterior branch.
The anterior branch ends near the margin of the great pectoral muscle. The
posterior branch communicates with the intercosto-humeral nerve, and then turns
round the posterior fold of the axilla, and, after giving a twig to the integument
of the arm, ends in the skin covering the dorsum of the scapula.
The anterior cutaneous nerves of the thorax are the terminal branches of the
upper intercostal nerves. They pierce the pectoralis major in company with the
perforating branches of the internal mammary artery. On reaching the surface of
the muscle, they give off minute twigs, which supply the skin over the sternum, and
then end in slender branches which are directed outwards to supply the skin cover-
ing the greater part of the pectoralis major. Some twigs from the third and fourth
nerves are distributed to the mammary gland.
C. Lower intercostal nerves.-The seventh, eighth, ninth, tenth, and eleventh
intercostal nerves, in the part of their course which lies between the ribs, present
the same relations as the upper intercostal nerves. On emerging from between the
ribs, they pass forwards between the internal oblique and transversalis muscles, and
usually communicate with one another in a plexiform manner in this situation.
They then pierce the outer edge of the sheath of the rectus, and, after supplying
the rectus, pass through the muscular substance and pierce the anterior part of the
sheath, where they end as the anterior cutaneous nerves of the abdomen.
Branches. The lower intercostal nerves supply the external and internal inter-
costal muscles, the levatores costarum, the serratus posticus inferior, the internal
oblique, the transversalis, and the rectus. They also give off lateral cutaneous
branches, by which the external oblique is supplied.
The lateral cutaneous nerves of the abdomen are the continuation of the series
of the lateral cutaneous nerves of the thorax. They divide into anterior and
posterior branches, which pierce the external oblique. The anterior branches are
directed forwards and somewhat downwards, and supply the integument covering the
anterior abdominal wall as far as the outer margin of the rectus. Each nerve gives
off a muscular twig, which pierces the adjacent digitation of the external oblique
muscle on its superficial surface. The posterior branches pass backwards around
the margin of the latissimus dorsi, and end in the skin of the outer part of the back.

846
THE NERVOUS SYSTEM
The anterior cutaneous nerves of the abdomen are the terminal branches of the
lower intercostal nerves, and pierce the anterior part of the sheath of the rectus to
supply the skin covering that muscle. These nerves are of small size, and sometimes
divide before their emergence, so as to form a double series.
D. Last thoracic nerve. This nerve gives off a communicating twig to the first
lumbar nerve, and then passes through the external arcuate ligament, and runs
outwards below the twelfth rib. It pierces the posterior aponeurosis of the trans-
versalis, and follows the curve of the abdominal wall between the transversalis and
internal oblique muscles. In the remainder of its course it resembles a lower
intercostal nerve. After piercing the rectus, however, it supplies the pyramidalis
(Griffin). Its lateral cutaneous branch remains undivided, and represents the
anterior division of an ordinary lateral cutaneous branch. On account of its
distribution, it is named the iliac branch. The iliac branch pierces the external
oblique about three inches above the iliac crest, and is directed downwards, across
the crest, a short distance behind the anterior superior spine. It ends in the
integument covering the anterior part of the gluteal region.
LUMBAR NERVES
The anterior divisions of the five lumbar nerves increase progressively in size
from above downwards, the first lumbar being about the size of an intercostal
nerve, and the fifth a nerve of considerable magnitude. The first, second, third,
and part of the fourth nerves unite to form the lumbar plexus. The remainder
of the fourth unites with the fifth to form the lumbo-sacral cord, which passes to
the sacral plexus. Each lumbar nerve is connected to the gangliated cord of
the sympathetic by rami communicantes. These rami communicantes reach the
lumbar nerves by accompanying the lumbar arteries through the fibrous arches
from which the psoas takes origin.
LUMBAR PLEXUS
The lumbar plexus is placed among the deeper fibres of the psoas, and is con-
stituted as follows: the first lumbar nerve is joined by a communicating twig from
the twelfth thoracic and divides into two branches; one of these is the common
origin of the ilio-hypogastric and ilio-inguinal nerves; the other branch unites with
a branch of the second lumbar to form the genito-crural nerve. The second,
third, and fourth lumbar nerves divide into anterior and posterior divisions. A part
of the anterior division of the second lumbar nerve enters into the composition of
the genito-crural nerve as above mentioned; the remainder of the anterior division
of the second nerve unites with the anterior division of the third and part of the
fourth nerve to form the obturator nerve. The remainder of the anterior division
of the fourth nerve enters the lumbo-sacral cord. The posterior divisions of the
second, third, and fourth nerves end chiefly in two large nerves-the external cuta-
neous and the anterior crural. The external cutaneous arises from the second and
third nerves. The anterior crural springs from the second, third, and fourth nerves.
A part of the posterior division of the fourth nerve enters the lumbo-sacral cord.
The large terminal branches above described are given off within the substance
of the psoas; three of these, the ilio-hypogastric, ilio-inguinal, and external cuta-
neous, appear at the outer border of the psoas, between that muscle and the
quadratus lumborum; one, the genito-crural, pierces the anterior fibres of the psoas
and appears in front of the muscle; another branch, the obturator, appears at the
inner border of the psoas close to the lower margin of the fifth lumbar vertebra;


LUMBAR PLEXUS
847
lastly, the anterior crural nerve, the largest branch of the plexus, runs downwards
in the interval between the psoas and iliacus. Within the psoas small twigs are
given off by the lumbar nerves, which end in the muscular substance of the psoas
and quadratus lumborum.
Branches. The nerves to the psoas and quadratus lumborum arise in an
irregular manner from the lumbar nerves within the substance of the
psoas.
The ilio-hypogastric and ilio-inguinal nerves are in some cases represented by
FIG. 461.-DIAGRAM OF THE LUMBAR AND SACRAL PLEXUSES. (Modified from Paterson.)
FROM LAST THORACIC
GENITO-CRURAL
ILIO-HYPOGASTRIC
ILIO-INGUINAL
EXTERNAL
CUTANEOUS
OBTURATOR
ACCESSORY
OBTURATOR
FIRST LUMBAR
SECOND LUMBAR
THIRD LUMBAR
FOURTH LUMBAR
FIFTH LUMBAR
BRANCH TO ILIACUS
ANTERIOR CRURAL
FIRST SACRAL
SECOND SACRAL
SUPERIOR GLUTEAL
INFERIOR GLUTEAL
GREAT SCIATIC
NERVE TO
QUADRATUS
FEMORIS
EXTERNAL
POPLITEAL-
THIRD SACRAL
VISCERAL
-FOURTH SACRAL
PERFORATING
CUTANEOUS
PERINEAL
FIFTH SACRAL
NERVE TO COCCYGEUS
NERVE TO LEVATOR
ANI
- FIRST COCCYGEAL
SECTION
INTERNAL
IP
POPLITEAL
SECTION
TO HAMSTRINGS
SMALL SCIATIC
VISCERAL
PUDIC
NERVE TO OBTURATOR INTERNUS
a common trunk which arises from the first lumbar. More commonly they exist
as two separate nerves, the upper and larger nerve being ilio-hypogastric; the
lower and smaller, ilio-inguinal. Taken together they correspond in many respects
to a lower intercostal nerve. They run for a considerable part of their course
between the transversalis and internal oblique, giving twigs to both these muscles.
The ilio-hypogastric gives off a lateral cutaneous, which is called the iliac branch,
and terminates in an anterior cutaneous which is termed the hypogastric branch.

848
THE NERVOUS SYSTEM
(1) The ilio-hypogastric nerve is a branch of the first lumbar. It appears at the
outer border of the psoas and crosses the quadratus lumborum obliquely to reach
the crest of the ilium. In this part of its course it is surrounded by the extra-
peritoneal fat. It then pierces the transversalis and runs along the crest of the
ilium between that muscle and the internal oblique, and, about two and a half
inches behind the anterior superior spine of the ilium, divides into an iliac and an
hypogastric branch. (a) The iliac branch pierces the internal and external oblique
muscles and crosses the crest of the ilium, lying close to the bone. It is directed
downwards towards the great trochanter of the femur; some of its twigs reach as
FIG. 462.-BRANCHES OF THE LUMBAR AND SACRAL PLEXUS VIEWED FROM BEFORE.
(After Hirschfeld and Leveillé.)
GANGLIATED CORD OF SYMPATHETIC
LAST THORACIC NERVE
FIRST LUMBAR-
ILIO-HYPOGASTRIC
ILIO-INGUINAL-
SECOND LUMBAR
AORTIC PLEXUS
LAST THORACIC NERVE
ILIO-
HYPOGASTRIC
ILIO-INGUINAL
THIRD LUMBAR
NERVE
FOURTH LUMBAR
ILIO-INGUINAL
EXTERNAL
CUTANEOUS
GENITO-CRURAL
LUMBO-SACRAL CORD
ANTERIOR CRURAL
OBTURATOR
GENITAL BRANCH OF-
GENITO-CRURAL
CRURAL BRANCH OF
GENITO-CRURAL
ILIO-INGUINAL
GENITO-CRURAL
EXTERNAL
CUTANEOUS
GENITAL BRANCH
OF GENITO-
CRURAL
CRURAL BR. OF
GENITO-CRURAL
OBTURATOR
DISTRIBUTION OF
EXTERNAL
CUTANEOUS
CRURAL BRANCH OF
GENITO-CRURAL
SACRAL PLEXUS
far as that prominence, and supply the integuments covering the fore part of the
gluteal region. (b) The hypogastric branch continues the direction of the main
trunk, and perforates the internal oblique near the anterior superior spine of the
ilium. In this part of its course it communicates in a plexiform manner with
the ilio-inguinal nerve. It is then directed forwards and inwards under cover of
the aponeurosis of the external oblique. Finally it pierces the aponeurosis at a
point about an inch above the external abdominal ring, and supplies the skin in
that situation, forming a continuation of the series of anterior cutaneous nerves of
the abdomen.

BRANCHES OF LUMBAR PLEXUS
849
(2) The ilio-inguinal nerve arises from the first lumbar nerve in common with
the ilio-hypogastric, and accompanies the last-named nerve across the quadratus
lumborum, but at a lower level. It then passes obliquely across the upper part of the
iliacus and pierces the transversalis muscle. It follows the curve of the crest of
the ilium in company with the ilio-hypogastric, communicating with that nerve in a
plexiform manner. It pierces the inferior oblique a little in front of the anterior
superior spine of the ilium, and runs forwards under cover of the aponeurosis of
the external oblique immediately above Poupart's ligament, and reaches the external
abdominal ring. It then traverses the ring and divides into its terminal branches,
which are distributed to the skin covering the upper part of the adductor longus,
the integuments of the scrotum in the male, and of the labium majus in the
female.
(3) The genito-crural nerve arises from the first and second lumbar nerve by two
roots which pass forwards and downwards through the fibres of the psoas, and unite
to form a single trunk. The nerve then appears on the surface of the psoas close
to the vertebral column, and runs downwards under cover of the peritoneum to
reach the outer side of the external iliac artery, where it divides into a genital and
a crural branch.
(a) The genital branch accompanies the spermatic vessels through the inguinal
canal, and, emerging from the external abdominal ring, pierces the internal
spermatic fascia, and is distributed to the cremaster muscle. In the female this
branch is rudimentary and accompanies the round ligament.
(b) The crural branch is carried downwards in front of the external iliac and
femoral artery into the external compartment of the femoral sheath. It pierces
the femoral sheath and becomes subcutaneous about two inches below Poupart's
ligament by piercing the fascia lata. It is distributed to the skin covering the upper
and central part of the anterior aspect of the thigh.
(4) The obturator nerve arises from the third and fourth lumbar nerves, and in
the majority of cases receives an additional root from the second. It passes between
the psoas muscle and the body of the fifth lumbar vertebra. It then runs down-
wards and forwards to reach the upper margin of the thyroid foramen. In this
part of its course it runs parallel to and a little below the brim of the pelvis, and
is placed in the extra-peritoneal fat between the peritoneum and the parietal pelvic
fascia. It is accompanied by the obturator vessels which are placed below it. The
nerve then passes through the deficiency in the obturator membrane, and divides
into two branches, an anterior and a posterior.
(a) The anterior branch passes across the upper border of the obturator
externus, and is directed downwards and inwards between the pectineus and
adductor brevis, and divides into the following branches :-(i) A twig for the hip
joint; (ii) a branch for the adductor longus; (iii) a branch to supply the adductor
brevis; (iv) a branch for the gracilis; (v) in rare cases, a twig for the pectineus;
(vi) a cutaneous branch. The cutaneous branch becomes superficial by passing
between the adductor longus and adductor brevis, and is then directed along the
posterior border of the sartorius, where it communicates with twigs from the long
saphenous and from the posterior branch of the internal cutaneous to form the
subsartorial plexus.
(b) The posterior branch gives off branches to supply the hip joint and the
obturator externus, and then pierces the upper part of that muscle, and reaches the
interval between the adductor brevis and adductor magnus. It runs downwards
on the anterior surface of the latter muscle, supplying it with twigs, and terminates
in an articular twig, the geniculate branch, which is distributed to the hip joint.
(i) The twig to the hip joint enters the acetabulum by passing through the cotyloid
notch. It ramifies in the fat occupying the floor of the acetabulum and in the
adjacent synovial membrane. (ii) The branch to the obturator externus pierces
3 I

850
THE NERVOUS SYSTEM
the deep surface of the muscle. (iii) Several large twigs enter the adductor magnus.
(iv) The geniculate branch pierces the lower part of the adductor magnus and
appears on the posterior surface of that muscle close to the opening for the popliteal
vessels, and descends on the inner side of (sometimes behind) the popliteal artery.
Having given off a filament which accompanies the superior internal articular
artery, it breaks up into terminal twigs which separately pierce the posterior
ligament of the knee joint.
FIG. 463.-ANTERIOR CRURAL AND OBTURATOR NERVES. (Ellis.)
Femoral vein
Pectineus
OBTURATOR (ANTERIOR DIV.)
OBTURATOR (POSTERIOR
DIVISION)
Adductor longus
Adductor brevis-
OBTURATOR
(ANTERIOR
DIVISION)
Gracilis
Adductor magnus
GENICULATE
BRANCH OF
OBTURATOR
Semi-membranosus
Anastomotica artery
PATELLAR BRANCH OF
LONG SAPHENOUS
Femoral artery
Sartorius
Iliacus
ANTERIOR CRURAL
Psoas
Tensor vaginæ femoris
Profunda artery
Pectineus
Rectus femoris
LONG SAPHENOUS
NERVE TO VASTUS
INTERNUS
Adductor longus
Femoral artery
An accessory obturator nerve is occasionally present. It arises from the obturator nerve
near its commencement, or by separate roots from the third and fourth lumbar nerves.
It runs along the inner border of the psoas, and crosses in front of the brim of the pubis
to gain the deep surface of the pectineus. In this situation it breaks up into branches.
The largest of these branches joins the obturator nerve, others enter the capsule of the hip
joint, and a branch is furnished to the pectineus.

ANTERIOR CRURAL NERVE
851
(5) The external cutaneous nerve arises, by two roots, from the second and
third lumbar nerves. It emerges at the outer border of the psoas, and crosses
obliquely in front of the iliacus to reach the interval between the anterior superior
and anterior inferior spines of the ilium. In this course it runs under cover of
the fascia iliaca. It then passes behind Poupart's ligament, crosses in front of the
origin of the sartorius, and divides into an anterior and a posterior branch. The
posterior branch passes backwards and downwards under cover of the fascia lata,
and divides into twigs, which supply the integument covering the insertion of the
gluteus maximus and the upper and outer part of the thigh. The anterior branch
FIG. 464.-DISTRIBUTION OF CUTANEOUS NERVES ON THE POSTERIOR AND ANTERIOR
ASPECTS OF THE INFERIOR EXTREMITY.
LAST
THORACIC
ILIO-
HYPOGASTRIC
EXTERNAL
CUTANEOUS
POSTERIOR
BRANCHES
OF LUMBAR
NERVES
POSTERIOR
BRANCHES
OF SACRAL
NERVES
PERFORATING
ILIO-
INGUINAL
EXTERNAL
CUTANEOUS
GENITO-
CRURAL
TWIG FROM
INTERNAL
MIDDLE
CUTANEOUS
CUTANEOUS
OF FOURTH
SACRAL
LONG
CUTANEOUS
PUDENDAL
BRANCHES OF
SMALL
SCIATIC
INTERNAL
OBTURATOR
CUTANEOUS
SMALL
SCIATIC
EXTERNAL
CUTANEOUS
COMMUNICANS
FIBULARIS
POSTERIOR
BRANCH OF
INTERNAL
CUTANEOUS
COMMUNI-
CANS
TIBIALIS
PATELLAR
BRANCH
OF LONG
SAPHENOUS
LONG
SAPHENOUS
SHORT
SAPHENOUS
TWIGS FROM
LONG
SAPHENOUS
INTERNAL
CALCANEAN
ANTERIOR
TIBIAL
CUTANEOUS
BRANCH OF
EXTERNAL
POPLITEAL
MUSCULO-
CUTANEOUS
SHORT
SAPHENOUS
is much larger than the posterior. It runs downwards for several inches in a
canal formed by the fascia lata, and enters the superficial fascia at the junction of
the upper with the middle third of the thigh. It divides into branches which supply
the skin of the outer part of the thigh, a few of the terminal twigs reaching as far
as the knee and entering into the composition of the plexus patellæ.
(6) The anterior crural nerve is the largest branch of the lumbar plexus. It
arises by three roots, which spring from the second, third, and fourth lumbar nerves;
these roots traverse the substance of the psoas and unite into a single trunk in the
deep groove between the psoas and iliacus muscles. The nerve then passes under
cover of the fascia iliaca behind Poupart's ligament, and is placed behind the
312

852
THE NERVOUS SYSTEM
femoral sheath at the outer side of the femoral artery. In this situation it divides
into its terminal branches; these branches may be classified into cutaneous and
muscular, some of the latter being associated with articular twigs. The muscular
branches are distributed to the iliacus, pectineus, sartorius, quadriceps extensor, and
subcrureus. The cutaneous branches are the middle and internal cutaneous and
the long saphenous.
(a) The nerves to the iliacus are given off from the anterior crural in the intra-
abdominal part of its course.
(b) The nerve to the pectineus arises immediately below Poupart's ligament.
It passes inwards behind the femoral vessels and the femoral sheath, and enters the
anterior surface of the muscle.
(c) The nerve to the sartorius is usually adherent to the middle cutaneous for
a part of its course.
(d) The nerves to the quadriceps are of large size and are distributed to the
four portions of the muscle. From the branch to the rectus an articular twig is
furnished to the hip joint. The nerves to the vasti give large twigs to the upper
and lateral portions of the capsule of the knee joint. The nerve to the crureus,
after giving branches to the upper part of the muscle, runs downwards between
the adherent borders of the crureus and vastus internus to reach the anterior
aspect of the lower end of the femur, where, after supplying the subcrureus, it ends
in the synovial membrane of the knee joint.
(e) The middle cutaneous nerve usually takes the form of two strong branches,
which run a nearly parallel course. One of these branches usually pierces the
sartorius, while the other crosses the superficial surface of that muscle; they pierce
the fascia lata a little above the middle of the thigh. They ramify in the super-
ficial fascia, supplying the skin of the anterior part of the thigh as far as the knee,
where they end in the plexus patellæ.
(f) The internal cutaneous nerve is directed downwards along the outer side of
the femoral artery, and gives off in this situation two or three cutaneous twigs, which
pierce the fascia lata. It then crosses obliquely in front of the femoral artery, at
the lower angle of Scarpa's triangle, and divides into an anterior and a posterior
branch. The anterior branch is the larger. It runs downwards in front of the
sartorius, under cover of the fascia lata. It pierces the fascia lata about the
middle of the lower third of the thigh, and, after giving twigs to the skin of that
region, turns outwards to end in the plexus patellæ. The posterior branch runs
along the posterior border of the sartorius, and, after giving twigs to the sub-
sartorial plexus, runs downwards on the inner aspect of the knee, and ends in the
integument of the upper and inner part of the calf.
Plexus patella. The skin covering the patella is profusely supplied with nerves which
communicate with one another, and are derived from the external, middle, and internal
cutaneous and from the long saphenous.
Subsartorial plexus.-At the posterior border of the sartorius muscle, a little below the
middle of the thigh, branches of the obturator, long saphenous, and internal cutaneous
nerves communicate in a plexiform manner and supply the adjacent skin. The posterior
branch of the internal cutaneous has an independent distribution, as already described.
Occasionally the cutaneous branch of the obturator is unusually large, and may supply an
area of integument covering the lower part of the inner hamstring muscles.

(g) The long or internal saphenous nerve accompanies the nerve to the vastus
internus in its course through Scarpa's triangle, being placed between the latter
nerve and the femoral artery. It enters Hunter's canal, and runs a parallel course to
the femoral artery, being supplied against the outer side of that vessel. At the lower
end of the canal it crosses in front of the femoral vessels, and runs on the deep
surface of the sartorius accompanied by the superficial branch of the anastomotic
artery. It passes between the tendons of the sartorius and gracilis, and becomes
COCCYGEAL PLEXUS
853
superficial a little below the knee. At this point it approaches the long saphenous
vein, and accompanies that vessel for the remainder of its course. It runs down
the anterior and inner part of the leg, supplying branches to the skin of that region,
passes in front of the inner malleolus, and supplies the integument for about two
inches below that prominence.
As it leaves Hunter's canal, the long saphenous nerve gives off a patellar
branch. This branch pierces the sartorius, and runs, at first downwards and
then inwards, towards the ligamentum patellæ. It gives twigs to the integument
covering that ligament, and others which curve upwards to join the plexus
patellæ.
SACRAL AND COCCYGEAL NERVES
The anterior primary divisions of the upper four sacral nerves escape from the
neural canal by passing through the anterior sacral foramina, while the anterior
division of the fifth passes forwards between the sacrum and coccyx. The
coccygeal nerve escapes from the neural canal by passing through the terminal
opening. Its anterior primary division pierces the sacro-sciatic ligaments and passes
forwards. The sacral nerves decrease progressively in size, from the first to the
fifth. The first sacral nerve is the largest nerve in the body, while the fifth is very
small. Each sacral nerve is connected to the gangliated cord of the sympathetic
by rami communicantes. The anterior divisions of the first, second, and part of the
fourth nerves join the sacral plexus; another part of the fourth has an independent
distribution. The lower part of the fourth joins the fifth sacral and the coccygeal
nerve to form the coccygeal plexus.
The branches of the fourth sacral nerve and the coccygeal plexus may be
conveniently described first, as their distribution is confined to a limited area in the
immediate neighbourhood of the sacral plexus.
FOURTH SACRAL NERVE
The fourth sacral nerve gives off an ascending branch to join the sacral plexus,
and a descending twig to the coccygeal plexus. In the interval between these
communicating branches, several offsets arise directly from the fourth sacral,
without entering into a plexiform arrangement. These direct offsets are the
perforating cutaneous nerve, the perinæal branch, and the muscular nerves to
the coccygeus and to the levator ani.
The perforating cutaneous branch runs in the angular interval between the
great and lesser sacro-sciatic ligaments, and then, perforating the former ligament,
runs between it and the gluteus maximus. It then winds round the border of that
muscle, behind the ischio-rectal fossa, and supplies the integument covering the
lower and inner part of the muscle (figs. 464, 466).
The perineal branch of the fourth sacral pierces the pelvic diaphragm,
between the contiguous margins of the coccygeus and levator ani, and appears
close to the tip of the coccyx. It is then directed forwards, and ends in twigs to
the external sphincter ani and to the integument of the anus.
The branches to the coccygeus and levator ani enter these muscles on their
deep or pelvic surface.

854
THE NERVOUS SYSTEM
COCCYGEAL PLEXUS
The anterior primary division of the fifth sacral nerve divides into ascending
and descending branches. The ascending branch unites with the descending
branch of the fourth sacral. The descending branch joins the coccygeal nerve. In
this manner two small loops are formed: these loops constitute the coccygeal plexus.
Anterior and posterior branches are given off by the plexus. The anterior
branches join the hypogastric plexus (Testut). The posterior branches pierce the
coccygeus muscle, and are distributed to the skin covering the posterior surface of
the coccyx. The coccygeal nerve gives a twig to the coccygeus and (according to
Testut) gives off a branch which pierces the great sacro-sciatic ligament and ends
in the lower fibres of the gluteus maximus.

SACRAL PLEXUS
The sacral plexus, with the exception of the roots of the lumbo-sacral cord, is
situated in the pelvis, behind the parietal pelvic fascia. It lies, for the most part,
on the pyriformis, the fibres of that muscle often interlacing with the roots of the
plexus. It is formed as follows: a part of the fourth lumbar joins the fifth lumbar
to form the lumbo-sacral cord; this cord is then joined by the first, second, and
third sacral nerves to form a great flattened band. This band is directed outwards
and downwards towards the lower margin of the great sacro-sciatic foramen, and,
on crossing that margin, is no longer called the sacral plexus, but takes the name
of the great sciatic nerve. A part of the fourth sacral nerve is joined by branches
from the second and third sacral nerves to form a second or lower band of
relatively small size, which ends in the pudic nerve. Several branches, to be
presently enumerated, spring from the plexus; but by far the larger part of the
plexus is directly continued into the great sciatic and pudic nerves. The plexus is,
therefore, more condensed and more simple in its formation than any other plexus
in the body. The two constituents of the lumbo-sacral cord unite to form that
structure on, or a little below, the brim of the pelvis. The plexus has the following
important vascular relations: the internal iliac vessels are placed a little in front
of its upper part; the gluteal artery passes between the lumbo-sacral cord and the
first sacral nerve; the sciatic artery passes through the lower part of the plexus
(fig. 466).
It has been shown (Paterson) that the anterior primary divisions of the lower four
lumbar and the upper two sacral nerves divide into anterior and posterior parts. The
branches derived from the anterior parts (lightly shaded in fig. 465) always cross in front
of the posterior parts and unite to form trunks (e.g. obturator, internal popliteal), which are
distributed to what is morphologically the anterior aspect of the limb. The trunks which
are formed from the posterior parts (e.g. external cutaneous, anterior crural, external
popliteal) are distributed to the (morphologically) posterior aspect of the limb; these nerves
are darkly shaded in fig. 465.
The branches of the sacral plexus are classified into collateral and terminal.
The collateral branches are the superior gluteal, the inferior gluteal, the nerve to
the pyriformis, visceral branches, the nerve to the quadratus, the small sciatic, and
the nerve to the obturator internus. The terminal branches are the great sciatic
and the pudic nerves.

The
COLLATERAL BRANCHES.-1. The superior gluteal nerve arises by two roots,
one from the lumbo-sacral cord, and the other from the first sacral nerve.
upper root contains fibres derived from the fourth and fifth lumbar nerves. The
nerve accompanies the gluteal vessels through the great sacro-sciatic foramen,
passing above the pyriformis. It then accompanies the deep division of the gluteal
artery into the interval between the gluteus medius and gluteus minimus, and,

BRANCHES OF THE SACRAL PLEXUS
855
having supplied both these muscles, ends in a branch which pierces the outer
fibres of the gluteus minimus, and supplies the tensor fasciæ femoris.
2. The inferior gluteal nerve arises from the posterior aspect of the plexus, and
contains fibres derived from the second and third sacral nerves. It escapes through
the great sacro-sciatic foramen, below the pyriformis, and in this situation is often
adherent to the small sciatic nerve. It divides into several stout twigs, which
enter the deep surface of the gluteus maximus.
FIG. 465.-DIAGRAM OF THE LUMBAR AND SACRAL PLEXUSES. (Modified from Paterson.)
FROM LAST THORACIC-
GENITO-CRURAL
ILIO-HYPOGASTRIC
ILIO-INGUINAL
EXTERNAL
CUTANEOUS
OBTURATOR
ACCESSORY
OBTURATOR
FIRST LUMBAR
-SECOND LUMBAR
THIRD LUMBAR
FOURTH LUMBAR
FIFTH LUMBAR
BRANCH TO ILIACUS
ANTERIOR CRURAL
FIRST SACRAL
SECOND SACRAL
SUPERIOR GLUTEAL
INFERIOR GLUTEAL
GREAT SCIATIC
NERVE TO
QUADRATUS
FEMORIS
EXTERNAL
POPLITEAL-
THIRD SACRAL
VISCERAL
FOURTH SACRAL
PERFORATING
CUTANEOUS
PERINEAL
FIFTH SACRAL
NERVE TO COCCYGEUS
NERVE TO LEVATOR
ANI
FIRST COCCYGEAL
SECTION
INTERNAL
POPLITEAL-
SECTION
TO HAMSTRINGS
SMALL SCIATIC
VISCERAL
PUDIC
NERVE TO OBTURATOR INTERNUS
3. The nerve to the pyriformis is given off either from the second or from the
third sacral nerve before they join the plexus.
4. The visceral branches arise from the third and fourth sacral nerves. They
will be described in connection with the sympathetic.
5. The nerve to the quadratus femoris is a branch of the third sacral nerve. It
passes through the great sacro-sciatic foramen below the pyriformis, and is usually
856
THE NERVOUS SYSTEM
adherent for some distance to the deep surface of the great sciatic in the part of its
course where it lies between the latter nerve and the bone. It then passes, under
cover of the tendon of the obturator internus and the gemelli, and, having supplied
the gemellus inferior, ends in the deep or anterior surface of the quadratus
femoris, and in the posterior part of the capsule of the hip joint.
6. The small sciatic nerve springs from the posterior aspect of the second
and third sacral nerves, and, passing downwards, escapes through the great sacro-
FIG. 466.-A DISSECTION OF THE LUMBAR AND SACRAL PLEXUSES, FROM BEHIND.
(The anterior crural nerve is placed between the external cutaneous and
obturator nerves.)

TWELFTH RIB
LAST THORACIC NERVE-
Psoas--
ILIO-
HYPOGASTRIC
ILIO-
INGUINAL-
ILIAC BRANCH.
OF ILIO-
HYPOGASTRIC
Gluteus medius
Gluteal artery
SUPERIOR
GLUTEAL NERVE
GREAT SCIATIC NERVE.
INFERIOR GLUTEAL
NERVE
SMALL SCIATIC NERVE
-Dura mater of cord
10
POSTERIOR PRIMARY
DIVISION
GENITO-CRURAL
CAUDA EQUINA
10
-Filum terminale
-EXTERNAL
CUTANEOUS
OBTURATOR
LUMBO-SACRAL CORD
-FIRST SACRAL
NERVE
FIFTH SACRAL
NERVE
VISCERAL BRANCHES
Sciatic artery
Small sacro-sciatic
ligament
PUDIC NERVE
NERVE TO
OBTURATOR
INTERNUS
PERFORATING
CUTANEOUS OF
FOURTH SACRAL
sciatic foramen by passing below the pyriformis. It then runs downwards on the
posterior surface of the great sciatic nerve, under cover of the gluteus maximus
muscle, to which it furnishes a branch. This branch is probably a portion of the
inferior gluteal nerve, which has adhered in a part of its course to the small sciatic.
It then runs vertically down the middle of the posterior aspect of the thigh, beneath
the fascia lata, crosses the popliteal space, and pierces the deep fascia a little below
the knee, to end in the integument of the upper part of the calf, where it may


BRANCHES OF THE SACRAL PLEXUS
857
communicate with the external saphenous nerve. In its course down the thigh
it gives off numerous branches, which pierce the fascia lata to supply the skin
covering the back of the thigh and the popliteal space. At the lower border of the
gluteus maximus it gives off (a) reflected branches, and (b) a large branch termed
the long pudendal nerve.
(a) The reflected branches, three or four in number, wind round the lower border
of the gluteus maximus, and, having pierced the deep fascia, supply the integument
covering the lower and outer part of that muscle.
(b) The long pudendal nerve, or nerve of Soemmerring, winds round the origin
of the hamstring muscles, just below the ischial tuberosity, giving twigs to the
integument on the inner and upper part of the thigh, and then curves upwards
and forwards towards the external genitals. Having pierced Colles's fascia, it
FIG. 467.-A DISSECTION OF THE NERVES IN THE GLUTEAL REGION.
(The gluteus maximus and gluteus medius have been divided near their insertions, and
thrown upwards.)
INFERIOR GLUTEAL NERVE
Gluteal artery
Gluteus medius
SUPERIOR
GLUTEAL NERVE-
Gluteus medius
Gluteus minimus-
Tensor fasciæ.
femoris
ERVE TO TENSOR.
ASCIE FEMORIS
Tendon of obturator externus-
Vastus externus
Sciatic artery
Gluteus maximus
BRANCH TO GLUTEUS
MAXIMUS
PUDIC NERVE
Great sacro-sciatic
ligament
[dici
-Comes nervi ischia-
-Gemellus inferior
-TUBEROSITY OF
ISCHIUM
LONG
PUDENDAL
Quadratus
femoris
Adductor
magnus
GT. SCIATIC
NERVE
SMALL
SCIATIC
Gluteus maximus
NERVE
communicates with the superficial perinæal nerves, and ends in the integument of
the scrotum. In the female it is distributed in a similar manner to the labium
majus.
7. The nerve to the obturator internus arises from the second and third nerves,
and is often united in a plexiform manner with the pudic. It passes through the
great sacro-sciatic foramen, below the pyriformis, and crosses the base of the ischial
spine, being placed on the outer side of the pudic vessels. Having furnished a
twig to the superior gemellus, it enters the lesser sacro-sciatic foramen, and ends
in the obturator internus.
TERMINAL BRANCHES.-1. The pudic nerve arises by three roots from the second,
third, and fourth sacral nerves, and escapes from the pelvis by passing through the
great sacro-sciatic foramen, below the pyriformis. It then crosses the posterior
surface of the small sacro-sciatic ligament, near the attachment of that ligament
to the spine of the ischium, and to the inner side of the pudic vessels. It then
accompanies the pudic vessels through the small sacro-sciatic foramen, and enters a

858
THE NERVOUS SYSTEM
canal formed by a delamination of the parietal pelvic fascia (Alcock's canal), and,
having given off the inferior hæmorrhoidal nerve, terminates by dividing into the
perinæal nerve and the dorsal nerve of the penis. At its origin, the pudic nerve is
often connected in a plexiform manner with the nerve to the obturator internus.
(a) The inferior hæmorrhoidal nerve pierces the wall of Alcock's canal, and
passes inwards through the fatty tissue which occupies the ischio-rectal fossa. It
is deeply placed at the outer part of the fossa, but becomes superficial as it
approaches the anus. It divides into terminal twigs, some of which supply the
external sphincter ani, while others are distributed to the adjacent integument.
(b) The perineal nerve runs for a short distance in Alcock's canal at a lower
level than the pudic vessels, and then divides into cutaneous and muscular divisions.
The cutaneous division takes the form of two nerves, which are termed posterior
and anterior superficial perinæal nerves. The posterior or external superficial
perinæal nerve escapes from Alcock's canal at the anterior part of the ischio-rectal
fossa, and, winding round the transverse perinæal muscle, passes forwards under
cover of Colles's fascia. It then divides into several long slender twigs, which
communicate with the anterior superficial perinæal and long pudendal nerves, and
end in the integuments of the scrotum. In the female they are distributed in a
similar manner to the labium majus. The anterior or internal superficial perinæal
nerve appears a little further forwards than the preceding nerve, and usually
passes through the fibres of the transverse perinæal muscle. Its terminal offsets
accompany the branches of the posterior perineal nerve, and have a similar
distribution. The muscular division of the perinæal nerve is more deeply placed
than the cutaneous division. It breaks up into the following branches: a twig to
the bulb of the urethra, and branches to supply the transversus perinæi, erector
penis (or clitoridis), accelerator urinæ (or sphincter vagina), and compressor urethræ
muscles.
(c) The dorsal nerve of the penis, which is placed at its origin below the pudic
artery, crosses that vessel and courses along above it. It then insinuates itself
between the layers of the triangular ligament and lies close to the bone at the outer
side of the pudic vessels. It then pierces the anterior layer of the triangular liga-
ment, and, having furnished a branch to the corpus cavernosum, passes between
the bone and the crus penis. It is then directed downwards on the dorsum penis
external to the dorsal artery. Having given off twigs to the prepuce, it ends in
branches to the glans. As it runs on the dorsum penis the nerve is under cover of
a thin strong fascia, and often appears in the form of two or three flattened parallel
bundles. The dorsal nerve of the clitoris is distributed in a similar manner to
the dorsal nerve of the penis, but is of much smaller size.
2. THE GREAT SCIATIC NERVE
The GREAT SCIATIC NERVE is the largest nerve in the body. It is, as above
mentioned, the main termination of the sacral plexus, and commences at the lower
border of the great sacro-sciatic foramen. It is directed vertically down the thigh,
and terminates a little below the middle of the thigh by dividing into the external
and internal popliteal nerves. In this course it is covered by the skin and fasciæ,
the gluteus maximus and biceps muscles, and the small sciatic nerve. Its deep
or anterior relations are the following, taken in order from above downwards:
the ischium, gemellus superior, tendon of obturator internus, gemellus inferior,
quadratus femoris, and adductor magnus.
Branches. The great sciatic nerve gives off branches in the thigh which supply
the hamstring muscles, and (in part) the adductor magnus. The nerve to the
semi-tendinosus usually arises from a more proximal part of the great sciatic than

EXTERNAL POPLITEAL NERVE
859
the other branches. Each head of the biceps is supplied with a separate branch.
The branches to the semi-membranosus and adductor magnus arise by a common
trunk.
In some cases the external and internal popliteal nerves arise separately from the
sacral plexus, a great sciatic nerve in the proper sense of the word being absent. In
such cases the nerves to the hamstrings are derived from the internal popliteal nerve.
(Paterson.)
The EXTERNAL POPLITEAL NERVE enters the superior angle of the popliteal space,
and runs downwards and outwards in contact with the inner border of the biceps.
It leaves the space by passing between the biceps tendon and the outer head of the
gastrocnemius. It then winds round the neck of the fibula between the bone and
the peroneus longus muscle, and terminates by dividing into the recurrent articular,
the musculo-cutaneous, and the anterior tibial nerves.
Branches. The branches of the external popliteal nerve may be classified into
articular, cutaneous, and terminal.
(1) The articular branches accompany the superior and inferior external
articular branches of the popliteal artery, and are distributed to the knee joint.
(2) The cutaneous branches are two in number, and often arise by a common
trunk. One of these is distributed to the skin covering the outer and upper part of
the leg. The other branch is termed nervus communicans peronei. It runs down-
wards and inwards beneath the deep fascia, and joins the nervus communicans
tibialis to form the external or short saphenous nerve (page 861).
(3) The recurrent articular nerve ends principally in the upper part of the
tibialis anticus muscle. A few fine filaments accompany the anterior tibial recurrent
artery to the front of the knee joint.
(4) The musculo-cutaneous nerve is directed downwards through the substance
of the peroneus longus, and is afterwards placed between the peroneus longus and
peroneus brevis muscles. Having given off branches to supply these muscles, it
divides into an external and an internal branch; these branches pierce the deep
fascia in the line of the intermuscular septum between the peronei and the
extensor group
of muscles. The external branch runs downwards in front of the
anterior annular ligament, and divides into the following branches: a twig which
communicates with the short saphenous; a branch which divides to supply the
adjacent sides of the fourth and fifth toes; and a branch which communicates with
the internal division of the musculo-cutaneous nerve. The internal branch crosses
the anterior annular ligament about an inch to the inner side of the external
branch, and divides into four branches; the first of these communicates with the
external branch, forming with it a nerve which bifurcates to supply the adjacent
sides of the third and fourth toes; the second divides to be distributed to the con-
tiguous sides of the second and third toes; the third communicates with the internal
terminal branch of the anterior tibial at the cleft between the great and second
toes; and the fourth supplies the inner border of the great toe.
From the two main divisions of the nerve a number of collateral twigs are
given off, which supply the integument of the lower part of the front of the leg and
the dorsum of the foot.
(5) The anterior tibial nerve pierces the intermuscular septum between the
peronei and extensors, and, having traversed the upper fibres of the extensor longus
digitorum, runs downwards on the interosseous membrane between the last-named
muscle and the tibialis anticus; lower down it is placed between the tibialis anticus
and the extensor longus hallucis. Finally it passes under cover of the anterior
annular ligament, and terminates in front of the bend of the ankle by dividing into
an external and an internal branch. In this course it is placed external to the
anterior tibial artery in the upper fourth of the leg, but lies on the anterior
surface of that vessel in the remainder of its course.
860
THE NERVOUS SYSTEM
Branches. In addition to the two terminal branches above mentioned, the
anterior tibial nerve gives off an articular twig to the ankle joint, and branches
FIG. 468.-DISTRIBUTION OF THE MUSCULO-CUTANEOUS AND ANTERIOR TIBIAL NERVES
ON THE ANTERIOR ASPECT OF THE LEG AND ON THE DORSUM OF THE FOOT.
(Hirschfeld and Leveillé.)

EXTERNAL POPLITEAL-
NERVE
RECURRENT ARTICULAR
MUSCULO-CUTANEOUS.
BRANCH TO PERONEUS.
LONGUS
-ANTERIOR TIBIAL
NERVE
BRANCH TO EXTENSOR-
LONGUS DIGITORUM
BRANCH TO PERONEUS
BREVIS
-Anterior tibial artery
Tibialis anticus
MUSCULO-CUTANEOUS-
MUSCULO-CUTANEOUS-
(OUTER DIVISION)
ANTERIOR TIBIAL
NERVE
MUSCULO-CUTANEOUS
(INNER DIVISION)
SHORT SAPHENOUS
ANTERIOR TIBIAL
(OUTER DIVISION)
ITS DISTRIBUTION TO
EXTENSOR BREVIS
DIGITORUM
ANTERIOR TIBIAL
(INNER DIVISION)
COLLATERAL
BRANCHES OF EX-
TERNAL SAPHENOUS-
AND MUSCULO-
CUTANEOUS TO TOES
COLLATERAL
BRANCHES OF
MUSCULO-CUTANEOUS
TO TOES
to supply the tibialis anticus, extensor longus hallucis, extensor longus digitorum,
and peroneus tertius. The branches destined for the two latter muscles arise in
INTERNAL POPLITEAL NERVE
861
common, and take the form of a long slender nerve which runs along the inner side
of the muscles, supplying them with numerous twigs.
The external branch is directed outwards under cover of the extensor brevis
digitorum, and, having supplied that muscle, ends in twigs which are distributed to
the tarsal articulations. This nerve presents a gangliform enlargement near its
commencement, thus resembling the anterior interosseous nerve in the superior
extremity.
The internal branch is directed forwards towards the interval between the first
and second toes, where it is joined by a twig from the musculo-cutaneous, and then
divides to supply the contiguous margins of the above-mentioned toes. In its
course on the dorsum pedis it lies to the outer side of the dorsal artery of the foot,
and it is crossed on its superficial surface by the innermost division of the extensor
brevis digitorum.
The INTERNAL POPLITEAL NERVE is larger than the peroneal nerve, and runs
downwards, following the same direction as the great sciatic, to reach the lower
border of the popliteus muscle, where it is continued into the posterior tibial nerve.
In this course it occupies the middle vertical diameter of the popliteal space, and is the
most superficially placed of the important contents of that space. It is overlapped
by the hamstring muscles above and by the heads of the gastrocnemius below; but
is covered only by the skin and fascia for about two inches above the line of the
knee joint. The popliteal vein intervenes between the internal popliteal nerve and
the artery, and the nerve is on a plane superficial to the vessels. In the upper part
of the popliteal space the vessels are internal to the artery; at the level of the
knee joint they are immediately in front of the nerve; and at the lower part of the
space they are placed external to it.
Branches. The branches of the internal popliteal nerve may be classified into
cutaneous, articular, muscular, and terminal.
(1) The cutaneous branch is termed nervus communicans tibialis. It arises
from the internal popliteal about the centre of the popliteal space, and runs vertically
downwards, under cover of the deep fascia, to reach the interval between the two
heads of the gastrocnemius; then, inclining a little outwards, it pierces the deep
fascia, and unites with the communicans fibularis to form the short saphenous
nerve.
(2) The external or short saphenous nerve is formed about the middle of the
calf (sometimes higher up or lower down), and runs downwards and outwards,
accompanied by the vein of the same name, to reach the interval between the
external malleolus and the calcaneum. It then runs forwards along the outer
border of the foot, supplying numerous twigs to the integument of the region.
Having communicated with the external branch of the musculo-cutaneous, it
terminates by supplying the integument on the outer side of the little toe.
Varieties. In a large number of cases the distribution of this nerve is much more
extensive. It may supply the fifth and fourth toes and the outer border of the third. In
some cases the communicans fibularis does not join the communicans tibialis, but ends
independently in the integuments of the calf.
(3) The muscular branches of the internal popliteal nerve are distributed to the
gastrocnemius, soleus, plantaris, and popliteus muscles. There is a separate branch
for each head of the gastrocnemius. The branch to the popliteus arises lower down
than the other branches. It crosses the superficial surface of the popliteal artery to
reach the outer side of that vessel, runs downwards on the posterior surface of the
popliteus, and winds round the lower border of that muscle to gain its deep or anterior
surface, where it ends in the muscular substance.
(4) The articular branches are three in number, and accompany the superior
and inferior internal articular and the azygos branches of the popliteal artery, to be
distributed to the knee joint.


862
THE NERVOUS SYSTEM
The POSTERIOR TIBIAL NERVE is the terminal branch of the internal popliteal, or
rather the direct continuation of that nerve. It runs downwards with an inclination
inwards to reach the interval between the inner malleolus and the os calcis, and,
having passed under cover of the origin of the abductor hallucis muscle, terminates
by dividing into the internal and external plantar nerves. In the upper part of its
course it is covered by the gastrocnemius, plantaris, and soleus muscles, and by the
intermuscular part of the deep fascia of the leg. Lower down, as it approaches the
FIG. 469.-SUPERFICIAL NERVES IN THE SOLE OF THE FOOT. (Ellis.)
Abductor hallucis
Abductor minimi digiti
Flexor brevis digitorum-
INTERNAL PLANTAR
NERVE
Internal plantar artery.
External plantar artery
EXTERNAL PLANTAR
NERVE
BRANCH OF IN-
TERNAL PLANTAR
NERVE TO INNER
SIDE OF HALLUX
DIGITAL COLLATERAL
BRANCHES OF
EXTERNAL
PLANTAR
DIGITAL COLLATERAL
BRANCHES OF
INTERNAL PLANTAR
ankle, it is covered only by the skin and fasciæ. Its anterior relations are the
tibialis posticus in the upper, and the flexor longus digitorum in the lower part
of its course. The posterior tibial vessels are placed externally to its upper part;
about the middle of the leg they cross in front of the nerve, and run downwards
parallel to its inner side.
Branches. The posterior tibial nerve supplies the three deep muscles of the
calf, viz. the tibialis posticus, flexor longus digitorum, and flexor longus hallucis.
SYMPATHETIC NERVES
863
It also furnishes one or two articular filaments to the ankle joint, and gives off a
cutaneous branch, the internal calcanean.
(1) The internal calcanean or calcaneo-plantar cutaneous branch arises from
the posterior tibial nerve a little above the level of the inner malleolus, and passes
under cover of the internal annular ligament, where it divides into several branches.
These branches pierce the internal annular ligament, accompanying the branches
of the internal calcanean artery, and are distributed to the thick fascia and integu-
ment which covers the heel and adjacent part of the sole.
(2) The internal plantar nerve is the larger of the two terminal branches of the
posterior tibial, and corresponds in its distribution to the median nerve in the hand.
It runs forwards in the interval between the abductor hallucis and the flexor brevis
digitorum; gives off branches to supply both these muscles, and a number of cuta-
neous twigs which appear in the interval between the middle and internal parts of
the plantar fascia. Near the level of the tarso-metatarsal articulation it terminates
by dividing into four digital branches. The first digital branch gives off a branch
to supply the flexor brevis hallucis, and then runs along the inner side of the great
toe as far as the extremity of that digit. The second branch gives off a twig to
supply the first or innermost lumbrical muscle, and then divides into two collateral
branches which supply the adjacent sides of the great and second toes. The third
branch divides in a similar manner to supply the contiguous sides of the second
and third toes. The fourth branch communicates with the superficial division of
the external plantar, and divides to supply the adjacent sides of the third and
fourth toes.
(3) The external plantar nerve shows many points of resemblance to the dis-
tribution of the ulnar nerve in the hand. From its origin at the termination of the
posterior tibial nerve, it is directed outwards and forwards between the flexor brevis
digitorum and the flexor accessorius. In this part of its course it supplies the
accessorius and the abductor minimi digiti. It is then directed forwards in the
interval between the last-named muscle and the flexor brevis digitorum, and termi-
nates at the level of the tarso-metatarsal articulations by dividing into a superficial
and a deep division. Previous to its division it gives off several cutaneous twigs,
which appear in the interval between the middle and external divisions of the
plantar fascia. The superficial division divides into two digital nerves, an external
and an internal. The internal branch supplies the interosseous muscles which
occupy the fourth interosseous space, and, having communicated with the internal
plantar, divides into two collateral branches which supply the contiguous sides of
the third and fourth toes. The external branch supplies the flexor brevis minimi
digiti, and is then directed along the outer border of the little toe to terminate at
the extremity of that digit. The deep division of the external plantar nerve runs
inwards and forwards on the dorsal or deep surface of the flexor tendons, and
ramifies in the interval between these tendons and the interosseous muscles. It
supplies the three outer lumbrical muscles, the interosseous muscles occupying the
three inner interosseous spaces, the transversus pedis, and the adductor hallucis.

SYMPATHETIC NERVES
The sympathetic nerves were formerly supposed to be a separate system, linked,
it is true, to the cerebro-spinal system by numerous communications, yet possessing,
in their ganglia, a certain governing power independent of the cerebro-spinal axis.
It is now very generally admitted that the sympathetic nerves are merely the

864
THE NERVOUS SYSTEM
visceral branches of the spinal nerves, but differ from the somatic nerves in the
following respects: (a) in the individual fibres being of smaller calibre than the
somatic nerve-fibres; (b) in the great preponderance of non-medullated fibres;
(c) in the fibres being interrupted in the nerve-cells, which are contained in a
chain of ganglia which is called the gangliated cord of the sympathetic, and often
also interrupted in secondary and tertiary ganglia, of which the semilunar ganglia
and the nerve-cells in the plexuses of Auerbach and Meissner are examples; and
(d) in the tendency that these nerves show to form extensive and closely-meshed
plexuses.
The somatic nerves are the nerves which supply the body-wall as distinguished
from the viscera. They have been described above as the cranial and spinal nerves.
Certain visceral nerves-for example, the visceral branches of the third and fourth
sacral nerves-do not join the gangliated cord. While the sympathetic nerves, taken as a
whole, can no longer be regarded as a separate system, certain ganglia connected with the
sympathetic are capable of automatic action; for example, the ganglia in the heart and in
the intestinal walls.
The sympathetic system, as usually described, consists of (a) a pair of gangliated
cords which are placed on the front and sides of the vertebral column; and (b) three
great prevertebral plexuses. One of these, the cardiac plexus, is contained in
the thoracic cavity. The other two, which are termed the solar and hypogastric
plexuses, are placed in the abdominal cavity. The gangliated cords will be first
described.
GANGLIATED CORDS OF THE SYMPATHETIC
The gangliated cords of the sympathetic consist of a series of ganglia united
together by intervening cords. These ganglia are of a reddish-grey colour, soft in
consistence, but enclosed in tolerably firm investments of connective tissue. The
nerve-cords uniting them are pearly grey in colour. Morphologically speaking,
there should be thirty-one pairs of ganglia, that is to say, a pair corresponding to
each pair of spinal nerves. We find, however, owing to the cohesion of certain
ganglia, particularly in the cervical region, that the number is reduced to from
twenty to twenty-three pairs. In the thoracic region the arrangement is the most
typical, as here we find twelve pairs of ganglia corresponding to the twelve thoracic
nerves. In the thoracic region, also, the arrangement of the rami communicantes is
most easily studied.
Each of the thoracic ganglia is connected to the corresponding spinal nerve by two rami
communicantes, a white and a grey. The white ramus communicans consists of medullated
fibres which enter the ganglion and pass through it towards the viscera. The grey ramus
communicans or revehent nerve is formed of non-medullated fibres, and passes back from
the ganglion to join the spinal nerve. It gives off afferent fibres which enter the spinal
cord, and efferent fibres which join the somatic division of the spinal nerve, and are thus
conveyed to the walls of the blood-vessels, forming vaso-motor nerves, and to the skin,
where they are distributed to the sweat glands.
Cranial portion of the sympathetic. The small sporadic ganglia (ophthalmic, spheno-
palatine, otic, and submaxillary), which have already been described in connection with
the trigeminal nerve, are regarded by some anatomists as representing a cranial portion of
the gangliated cord.
CERVICAL PORTION OF THE GANGLIATED CORD
The cervical portion of the gangliated cord consists of three ganglia united by
intervening nerve-cords. Of these the superior cervical ganglion is the largest, and
probably represents four coalesced ganglia; the middle cervical ganglion is the
smallest, and represents two ganglia; the inferior, intermediate in size, is probably

SYMPATHETIC NERVES
865
formed by the union of two ganglia. The cord takes a vertical course down the
neck, and is in contact posteriorly with the prevertebral layer of the cervical fascia.
Behind this fascia it corresponds to the rectus capitis anticus major above, and the
longus colli below. These muscles and the prevertebral fascia intervene between
the cord and the transverse processes of the cervical vertebræ. The internal carotid
above, and the common carotid artery below, are placed in front of the gangliated
cord, and the pneumogastric nerve is external to it.
SUPERIOR CERVICAL GANGLION
The superior cervical ganglion is a fusiform body, about one inch to an inch
and a half in length. It corresponds to the transverse processes of the second and
third (and sometimes the first) cervical vertebræ. Above, it is continued into a
stout trunk which is called the ascending branch. Below, it ends in a cord which
passes downwards to join the middle cervical ganglion. It is connected to the
anterior primary divisions of the four upper cervical nerves by as many rami com-
municantes. Occasionally the number of rami is increased to five or six. The
ganglion is occasionally constricted at intervals-these constrictions affording an
indication of the individual ganglia by the coalescence of which the superior
cervical ganglion is formed.
Branches.-The branches of the superior cervical ganglion are the ascending
branch; branches which follow the distribution of the external carotid artery (nervi
molles); branches of communication to cranial nerves; pharyngeal nerves; and
the superior cervical cardiac nerve.
1. The ascending branch enters the carotid canal in the temporal bone and
divides into a larger external branch which forms the carotid plexus, and a smaller
internal branch which ends in the cavernous plexus. These plexuses communicate
frequently with one another around the artery, and may be regarded as different
parts of the same plexus rather than distinct plexuses.
The carotid plexus is formed by repeatedly communicating branches, which
follow the internal carotid artery in the carotid canal, keeping close to the outer
side of that vessel. The following nerves arise from it: tympanic; great deep
petrosal; and a communicating branch to the sixth nerve.
(a) The tympanic branch (small deep petrosal) enters a minute canal (carotico-
tympanic canal) in the temporal bone, by which it is conducted to the tympanic
plexus (page 814).
(b) The great deep petrosal nerve passes forwards and inwards through the
cartilage which occupies the foramen lacerum medium, and unites with the great
superficial petrosal to form the Vidian nerve (page 800).
(c) The branches to the Gasserian ganglion are given off from the plexus as it
emerges from the carotid canal.
(d) The branches to the sixth nerve are very distinct, and can be easily seen
when the cavernous sinus is opened. They join the abducens as it is crossing the
outer side of the internal carotid artery.
The cavernous plexus is placed on the inner side of the internal carotid artery
near the pituitary body. Its terminal offsets follow the ophthalmic and cerebral
branches of the internal carotid artery. In addition to these it gives off the
following branches:
(a) Communicating branches to the third, fourth, and ophthalmic division of
the fifth cranial nerves.
(b) The sympathetic root of the lenticular ganglion. This root is usually in
the form of several fine filaments which enter the ganglion at its posterior border.
(c) Two or three fine twigs enter the pituitary body.
2. The nervi molles are given off from the anterior part of the superior cervical
T
3 K

866
THE NERVOUS SYSTEM
FIG. 470.-THE CERVICAL PORTION OF THE SYMPATHETIC AND THE DISTRIBUTION
OF THE PNEUMOGASTRIC NERVE, VIEWED FROM BEHIND. (Krause.)
Ligamentum pharyngeum
Stylo-hyoid
X
XI
IX
XII
Posterior belly of
digastric
Sterno-mastoid
Rectus capitis
anticus major
Stylo-pharyngeus
Stylo-glossus
Internal pterygoid
SUPERIOR
CERVICAL
GANGLION
Middle constrictor
Internal carotid
artery
RIGHT
SYMPATHETIC
Occipital artery
Posterior belly of
digastric
Common carotid
Tos artery
Inferior constrictor
GANGLION
THYROIDEUM
(VARIETY)
THYROID GLAND
Inferior thyroid-
artery
Subclavian artery.
DESCENDENS
HYPOGLOSSI
Common carotid
artery
Sterno-mastoid
TWIG OF
RECURRENT
LARYNGEAL TO
PHARYNGEAL
PLEXUS
Thyroid axis
INFERIOR
CERVICAL
RECURRENT
LARYNGEAL
NERVE
mas lines od
Thoracic aorta-
Crus of diaphragm
GANGLION
-RECURRENT
LARYNGEAL
-PLEXUS GULE
RIGHT
PNEUMOGASTRIC
ganglion, and accompany the branches of the external carotid artery. We have
already noted, in the description of the fifth cranial nerve, that the otic and sub-
maxillary ganglia receive their sympathetic roots from plexuses of the sympathetic
23
CERVICAL GANGLIONS
867
which reach them via the middle meningeal and facial arteries respectively. In
addition to these roots to the ganglia, vaso-motor branches, and twigs which enter
the parotid gland, are given off. Other twigs, taking a downward direction, enter
the intercarotic and thyroid bodies; the latter follow the course of the superior
thyroid vessels.
3. Communicating branches to cranial nerves.-Branches of communication
arise directly from the ganglion to join the vagus, glosso-pharyngeal, and hypo-
glossal nerves. Communications are effected with the ganglia of the root and trunk
of the vagus, and with the jugular and petrous ganglia of the glosso-pharyngeal.
4. The pharyngeal branches, four or five in number, pass downwards and
inwards behind the external and internal carotid arteries to join the pharyngeal
plexus.
5. The superior cervical cardiac nerve arises from the lower part of the
ganglion, or occasionally from the nerve-cord between the superior and middle
cervical ganglia. The nerves of the two sides run a corresponding course in the
neck, but differ in their arrangement in the thorax. In the neck, each nerve is
directed downwards on the prevertebral fascia in front of the longus colli muscle,
and communicates with the upper cervical cardiac branch of the pneumogastric,
with the middle cardiac nerve of the sympathetic, and with the external laryngeal
and recurrent laryngeal nerves.
On the right side the nerve passes in front of (occasionally behind) the sub-
clavian artery, and is directed along the innominate artery to reach the bifurcation
of the trachea, in front of which it terminates in the deep cardiac plexus.
On the left side the nerve is conducted into the thorax in front of the common
carotid artery, and crosses in front (or rather to the left side) of the so-called
transverse part of the arch of the aorta in the interval between the trunk of the
vagus and its inferior cervical cardiac branch, and ends in the superficial cardiac
plexus.
MIDDLE CERVICAL GANGLION
The middle cervical ganglion is a small, somewhat triangular, ganglionic
thickening of the cord of the sympathetic. It is situated at the point where the
cord crosses the inferior thyroid artery at the level of the sixth cervical vertebra.
It is joined by rami communicantes from the fifth and sixth cervical nerves. It is
connected below to the inferior cervical ganglion by the main cord of the sympa-
thetic, which passes behind the subclavian artery, and by one or more nerve-cords
which pass in front of that vessel, forming the ansa Vieussenii. The middle
cervical ganglion gives off branches to the thyroid body and the middle cardiac
nerve.
The branches to the thyroid body communicate with the superior cardiac
nerve, and proceed to the gland, following the branches of the inferior thyroid artery.
The middle cardiac nerve enters the thorax, passing sometimes in front of the
subclavian artery, and sometimes behind that vessel. It communicates in the neck
with the upper cardiac nerve, and in the thorax with the recurrent laryngeal. It
terminates in the deep cardiac plexus.

INFERIOR CERVICAL GANGLION

The inferior cervical ganglion is larger than the middle ganglion, and is con-
nected by short rami communicantes to the seventh and eighth cervical nerves.
It is irregular in form and is deeply placed, being lodged in a depression between
the neck of the first rib and the transverse process of the seventh cervical vertebra.
In this situation it is concealed by the vertebral artery, the vessel being placed in
front of the ganglion. It is united to the first thoracic ganglion by one or two stout
3K2

868
THE NERVOUS SYSTEM
cords and often by a band of ganglionic substance. It gives off branches to the
vertebral artery and the inferior cardiac nerve.
The branches to the vertebral artery are of considerable size and accompany
the vessel into the arterio-vertebral foramina in the transverse processes. The
plexus thus formed is continued on the vertebral and basilar to the cerebral arteries.
The inferior cardiac nerve communicates with the middle cardiac and recurrent
laryngeal, and passes along the side of the trachea to join the deep cardiac plexus.
It occasionally arises from the first dorsal ganglion.
THORACIC PORTION OF THE GANGLIATED CORD
The thoracic portion of the gangliated cord is represented by a chain of twelve
pairs of ganglia. In a few cases, on account of the coalescence of some of the
members of the series, the number may be reduced to eleven or ten pairs. The
upper ten ganglia lie upon the heads of the corresponding ribs, immediately under
cover of the pleura. The lower two are placed further forwards, and lie on the
sides of the bodies of the eleventh and twelfth thoracic vertebræ between the bones
and the diaphragm. The cord is continuous above with the cervical part of the
cord, the first thoracic ganglion being sometimes united across the neck of the first
rib with the inferior cervical ganglion. Below, the cord enters the abdominal
cavity by passing through the crus of the diaphragm to become continuous with
the lumbar part of the cord. The first thoracic ganglion (ganglion stellatum) is
larger than the others, and is of an irregular form. The remainder of the series
are triangular in outline, two of the angles being continued into the interganglionic
part of the cord, and the other into the rami communicantes. On some of the
lower ganglia a fourth angle makes its appearance, and is continued into one of
the roots of the splanchnic nerves.
Branches. The branches are classified into external and internal. The
external branches are the rami communicantes. A grey and a white ramus
communicans connects each ganglion with the corresponding thoracic nerve. The
internal branches of the upper four ganglia are distributed chiefly to the aorta and
lungs. The internal branches of the lower eight ganglia form three splanchnic
nerves which are distributed to the abdominal viscera.
Internal branches-Upper series. From the upper four or five ganglia fine
twigs arise which are distributed to the thoracic aorta, mediastinum, and lungs.
Internal branches-Lower series.-These branches, although arising in the
thorax, are destined for the abdominal viscera. The branches from the fifth to the
ninth ganglia unite to form the great splanchnic nerve; the lesser splanchnic nerve
arises by two roots from the tenth and eleventh ganglia, while the internal branch
of the twelfth ganglion forms the smallest splanchnic nerve.
GREAT SPLANCHNIC NERVE. The five roots of this nerve run downwards and
inwards between the pleura and the bodies of the thoracic vertebræ, and unite.
within the posterior mediastinum to form a trunk of considerable size. The nerve
thus formed pierces the crus of the diaphragm, and enters the semilunar ganglion
of its own side.
The great splanchnic nerve is whitish in colour, owing to a number of medullated
fibres entering into its composition. Occasionally a small ganglion (splanchnic ganglion)
is developed upon it in the mediastinum. This ganglion is constant on the right side.
(Cunningham.)
The LESSER SPLANCHNIC NERVE runs a similar course to the great splanchnic,
but at a lower level. It pierces the crus of the diaphragm, or passes through the
internal arcuate ligament, and enters the solar and renal plexuses.
The SMALLEST SPLANCHNIC NERVE passes through the internal arcuate ligament
and enters the renal plexus.

GREAT PREVERTEBRAL PLEXUSES
869
LUMBAR PORTION OF THE GANGLIATED CORD
The lumbar part of the gangliated cord consists of a chain of ganglia, usually
four in number, which are placed in front of the bodies of the vertebræ, close to
the anterior border of the psoas muscle. On the right side the cord is covered by
the vena cava, and on the left side it is behind and external to the aorta. Above,
it is continuous with the thoracic part of the cord. Below, it is continued into the
sacral part of the cord by passing behind the common iliac vessels. The rami
communicantes are longer in this part of the gangliated cord than in any other
region of the body. Usually two rami pass from each ganglion backwards through
the fibrous arches from which the psoas takes origin, and join the lumbar nerves
in a somewhat variable manner. In this course they are accompanied by the
lumbar arteries.
Branches. Some of the branches join the aortic plexus; others pass in front of
the common iliac arteries to form the hypogastric plexus.
SACRAL PORTION OF THE GANGLIATED CORD
The sacral part of the gangliated cord consists of a chain of four small ganglia,
which is placed in front of the sacrum internal to the anterior sacral foramina.
From the lowest of these ganglia, branches proceed on each side which converge to
a median ganglion (ganglion impar) which is situated in front of the last piece
of the sacrum or the first piece of the coccyx. These ganglia are connected in
a somewhat irregular manner to the sacral nerves by rami communicantes. The
rami communicantes are very short in this region.
Branches. From the upper sacral ganglia branches are given off which join
the pelvic plexuses. Others pass across the sacrum to join corresponding branches
from the cord of the opposite side. From the ganglion impar twigs pass down-
wards to enter the coccygeal body.
THE GREAT PREVERTEBRAL PLEXUSES
The great prevertebral plexuses, as we have already noticed, are the cardiac,
solar, and hypogastric. They are formed mainly by branches derived from the
gangliated cords, but also receive fibres from the cerebro-spinal nerves; thus the
cardiac plexus and solar plexuses are joined by branches of the pneumogastric, and
the hypogastric plexus is joined by branches of the third and fourth and sometimes
the second sacral nerves.

CARDIAC PLEXUS
We have already noticed that each pneumogastric nerve gives off two or
three cervical cardiac branches and a thoracic cardiac branch, and that additional
branches may spring from the recurrent laryngeal nerve. We have also seen that
three cardiac nerves arise from the cervical sympathetic cord on each side. These
nerves all proceed to the cardiac plexus, but their course and arrangement is
extremely variable. It is very common to find the upper cervical cardiac branches
of the vagus and sympathetic unite to form a common trunk; in other cases the
nerves branch and communicate with one another in a plexiform manner. The
cardiac plexus, although forming a continuous network of nerves, is for convenience
divided into a superficial and a deep plexus. The superficial plexus is situated
immediately below the arch of the aorta, internal to the ductus arteriosus; it
receives the left superior cardiac nerve of the sympathetic and the left inferior
cervical cardiac branch of the pneumogastric. The deep cardiac plexus is placed
870
2323 THE NERVOUS SYSTEM
in front of the bifurcation of the trachea between that structure and the transverse
part of the aortic arch; it receives all the other cardiac nerves.
Superficial cardiac plexus.-The superior cardiac branch of the sympathetic
and the inferior cervical cardiac branch of the vagus cross the so-called transverse
part of the aortic arch on its left side, being placed between the artery and the left
pleura. The nerves then enter the interval between the aortic arch and the
bifurcation of the pulmonary artery, where they communicate with the deep
cardiac plexus. A small ganglion (the cardiac ganglion of Wrisberg) is usually
developed at the point of communication. Branches are furnished to the right
coronary plexus and also to the left lung. The latter branches join the anterior
pulmonary plexus.
Deep cardiac plexus.-The deep cardiac plexus receives all the right cardiac
nerves, and also the cardiac nerves of the left side, with the exception of the
superior cervical cardiac of the sympathetic and the inferior cervical cardiac
of the vagus. The plexus is placed in front of the bifurcation of the trachea,
and gives off the following branches :-(a) Branches to the anterior pulmonary
plexuses of both sides; (b) the left coronary plexus; (c) branches to the right
auricle; (d) communicating branches to the superficial cardiac plexus; and
(e) branches to the right coronary plexus.
Right coronary plexus.-This plexus is formed by branches from both the
superficial and deep cardiac plexuses. It follows the branches of the right coronary
artery for a certain distance, beyond which the nerves diverge from the arteries, and
run between the pericardium and the muscular substance of the heart. Finally
they enter the muscular substance.
Left coronary plexus.-This plexus arises from the deep cardiac plexus.
It passes forwards between the left auricular appendix and the pulmonary artery,
and accompanies the branches of the left coronary artery.
SOLAR PLEXUS
The solar plexus is placed in front of the commencement of the abdominal aorta.
It is the largest of the prevertebral plexuses, and is formed by the two semilunar
ganglia, and by a number of interlacing nerve-cords which surround the ganglia.
Each semilunar ganglion is placed at the side of the cœliac axis, embracing the
artery in its concavity. The upper and the lower extremities of the ganglia of
opposite sides are connected to one another by nerve-cords, above and below the
artery. In this manner the cœliac axis is surrounded by a neuro-ganglionic collar.
From this neuro-ganglionic collar a number of branches arise which are joined by
branches from the right vagus and by both small splanchnic nerves, and in this
manner the solar plexus is formed. From the solar plexus a number of nerves
arise which accompany the abdominal aorta and its branches, forming secondary
plexuses, which take their names from the arteries they accompany.
Semilunar ganglia.-These are a pair of reddish-grey, irregularly shaped bodies
which rest on the crura of the diaphragm, close to the coeliac axis. The great
splanchnic nerve on each side, after piercing the crus of the diaphragm, enters the
outer, or convex, side of the corresponding ganglion.
Coeliac plexus.-The coeliac plexus surrounds the coeliac axis, and divides into
splenic, hepatic, and coronary plexuses.
The splenic plexus, after receiving a communication from the right pneumo-
gastric nerve, accompanies the splenic artery to the spleen. It gives off pancreatic
and left gastro-epiploic plexuses.
The hepatic plexus is joined, near the pyloric end of the stomach, by branches
from the left pneumogastric, and accompanies the hepatic artery to the liver, where
it divides into right and left hepatic plexuses. Previous to its division, it gives off
MA SOLAR PLEXUS
871
pyloric, right gastro-epiploic, and pancreatico-duodenal plexuses. From the right
hepatic plexus a cystic plexus is furnished to the gall-bladder.
The coronary plexus follows the lesser curvature of the stomach, proceeding
from left to right. In this course it is joined by branches from the left pneumo-
gastric, and, after giving off numerous twigs to the stomach, ends, near the pylorus,
by joining the pyloric plexus.
The diaphragmatic plexuses arise from the upper extremities of the semilunar
ganglia, and accompany the diaphragmatic arteries to the under surface of the
diaphragm. On the right side a communication is effected with the phrenic nerve,
a small ganglion (ganglion diaphragmaticum) being formed at the point of commu-
nication.
The suprarenal plexuses are derived, in part from the diaphragmatic, in part
from the solar, and in part from the renal plexuses; they are distributed chiefly
to the medullary portions of the suprarenal bodies.
The renal plexuses are formed by branches of the solar and aortic plexuses,
and are joined posteriorly by the smallest splanchnic nerves. Each renal plexus
surrounds the corresponding renal artery, and enters the hilum of the kidney, where
it subdivides in the fatty tissue which occupies the sinus, and enters the substance
of the kidney with the blood-vessels.
The superior mesenteric plexus is of large size, and is remarkable for the
comparatively white colour of the nerves which compose it. It is derived from
the solar plexus, and, after emerging from under cover of the pancreas, closely
surrounds the trunk of the superior mesenteric artery. In this situation a few
ganglia (ganglia mesenterica) are formed. Having given off branches, which
accompany the colica media, colica dextra, and ileo-colic arteries, the greater part of
the plexus enters the mesentery, where the nerves-no longer closely following
the blood-vessels, spread out between the layers of the mesentery, and eventually
reach the small intestine.
The aortic plexus is in the form of two vast networks of nerves which are
massed along the sides of the abdominal aorta, and are connected by commu-
nicating branches which pass across the front of the great vessel. It is formed
mainly by the downward continuation of the solar plexus, but receives strong
reinforcements from the upper three lumbar ganglia. It gives off the spermatic
and inferior mesenteric plexuses, and terminates below in strong branches to the
hypogastric plexus.
The inferior mesenteric plexus is much smaller than the superior mesenteric
plexus, but, like the latter, is remarkable for its whitish colour. It is derived from
the aortic plexus, and is conveyed by the branches of the inferior mesenteric artery
to the descending colon, the sigmoid flexure, and to the upper part of the rectum.
In the latter situation it communicates with the pelvic plexuses.
The spermatic plexus is derived from the aortic and renal plexuses. It accom-
panies the spermatic artery as far as the internal abdominal ring, where it is joined
by a fine plexus derived from the pelvic plexus and accompanying the vas deferens.
Thus reinforced, it is conducted by the spermatic cord to the testicle.
In the female it accompanies the ovarian vessels to the ovary and uterus.

HYPOGASTRIC PLEXUS

From the lower ganglia of the lumbar sympathetic cord, two or three strong
branches proceed which cross obliquely in front of the common iliac arteries. These
nerves are joined by stout offsets from the aortic plexus, and interlace in front of
the body of the fifth lumbar vertebra with the corresponding nerves of the opposite
side to form a broad flattened band, which is termed the hypogastric plexus. This
plexus is remarkable in that it contains little or no ganglionic matter. It soon
divides into two lateral portions, the pelvic or inferior hypogastric plexuses.
872
THE NERVOUS SYSTEM
FIG. 471.-LUMBAR PORTION OF THE GANGLIATED CORD, WITH THE SOLAR AND
HYPOGASTRIC PLEXUSES. (Henle.)
GANGLION DIAPHRAGMATICUM
Hepatic artery

SUPRARENAL
CAPSULE
GREAT
SPLANCHNI
NERVE
RIGHT
SEMILUNAR
GANGLION
RENAL GANGLION
SMALL
SPLANCHNIC
NERVE
Renal artery
GANGLIATED CORD
RAMUS COMMUNICANS
BRANCH TO AORTIC
PLEXUS
Sextoj
an
LEFT SEMI-
LUNAR GANGLION
GREAT
SPLANCHNIC
NERVE
SMALL
SPLANCHNIC
NERVE
Superior mesenteric
artery
RENAL GANGLION
Renal artery
SUPERIOR MESENTERIC
GANGLION
-BRANCH TO AORTIC
PLEXUS
GANGLIATED CORD OF
SYMPATHETIC
-Inferior mesenteric artery
INFERIOR MESENTERIC
GANGLION
Disk between last lumbar
and first sacral vertebra
Common iliac vein
Common iliac artery
PELVIC PLEXUSES
873
PELVIC PLEXUSES
Each of the two lateral continuations of the hypogastric plexus passes downwards
on the side of the rectum, where it is joined by slender branches from the sacral
part of the gangliated cord, and by branches from the third and fourth (sometimes
the second) sacral nerves. In this manner the pelvic plexuses are formed. Each
pelvic plexus gives off branches to the pelvic viscera; these branches, in the
greater part of their course, follow the arteries of the pelvis. We distinguish
middle hæmorrhoidal, vesical, prostatic, and (in the female) vaginal and uterine
plexuses.
The middle hæmorrhoidal plexuses form a closely-meshed expansion on the
sides of the rectum; they communicate above with branches from the inferior
mesenteric plexus, and below with the inferior hæmorrhoidal branches of the pudic
nerve.
The vesical plexus is chiefly formed by fibres derived from the third and fourth
sacral nerves. The nerves pass forwards on each side of the bladder, and divide
into two groups-a superior group, which supplies the upper two-thirds of the
bladder; and an inferior group, which is distributed to the lower third of that
viscus. In the male, branches are given off to the vesiculæ seminales and vasa
deferentia. The nerves to the vas deferens form a slender plexus which accom-
panies that structure as far as the internal abdominal ring, where it unites with the
spermatic plexus.
The prostatic plexus is placed a little lower down than the vesical plexus, of
which it is in some measure a continuation. The nerves which pass to it are
of relatively large size, and are massed on the sides of the organ, where several
ganglionic masses, from one-eighth to a quarter of an inch in length (ganglia
prostatica of Müller), are developed. From the prostatic plexus, offsets are
furnished to the vesiculæ seminales, and also branches to the erectile structures of
the penis; the latter branches are called cavernous nerves.
The small cavernous nerves are several fine twigs which pierce the layers of the
triangular ligament and the muscular structures which surround the membranous
portion of the urethra. They enter the corpora cavernosa just in front of the
subpubic ligament.
The large cavernous nerve takes a similar course through the triangular liga-
ment, and runs forwards on the dorsum penis as far as the middle of the organ,
where it communicates with the dorsal nerves of the penis. It ends in twigs to the
corpus cavernosum.
In the female there are similar nerves, but of much smaller size, distributed to
the clitoris.
The vaginal plexus is formed largely by branches from the sacral nerves. It
ramifies on the sides of the vagina, giving off twigs to the erectile substance, and to
the mucous membrane. A few fine twigs pass forwards to reach the clitoris.
The uterine plexus accompanies the uterine artery between the layers of the
broad ligament, and, having received communicating twigs from the ovarian plexus,
enters the muscular substance. In the gravid uterus this plexus is increased in
size, chiefly on account of an hypertrophy of the connective tissue sheaths of the

nerves.
SECTION VI
ORGANS OF SPECIAL SENSE
THE EYE
By R. MARCUS GUNN, M.A., F.R.C.S.
SURGEON TO THE ROYAL LONDON OPHTHALMIC HOSPITAL, MOORFIELDS; ASSISTANT OPHTHALMIC SURGEON TO
UNIVERSITY COLLEGE HOSPITAL.
THE EYEBALL AND ITS SURROUNDINGS
GENERAL SURFACE VIEW
This examination is to be made prior to any disturbance of the parts, and is, indeed, best
conducted on the living body. A pocket magnifying lens should be at hand for use when
required.
THE
HE two eyes are situated nearly in the line where the upper and middle thirds
of the face meet; they lie right and left of the root of the nose, the most
prominent part of the front of each globe being about an inch and a quarter from
the middle line of the face. Each eye is overshadowed by the corresponding
eyebrow, and is capable of being concealed by its eyelids, upper and lower.
The orbital margin may be traced all round with the finger. At the junction of
the inner and middle thirds of the upper margin, the supraorbital notch can usually
be felt, and the supraorbital nerve passing through it can sometimes be made to roll
from side to side under the finger. The inner margin is the most difficult to trace
in this way, partly because it is more rounded off than the others, partly because
it is bridged over by a firm fibrous band (tendo oculi, or inner palpebral ligament),
passing inwards from the eyelids; below this band, however, a sharp bony crest is
felt, which lies in front of the lachrymal sac. Note how the eye is protected by the
rim of the orbit, above and below; if we lay a hard flat body over the orbital opening,
it will rest upon the upper and lower bony prominences, and will not touch the
surface of the globe. Inwards, the eye is protected from injury mainly by the
bridge of the nose; outwards it is most readily vulnerable, as here the orbital rim
is comparatively low. With one finger placed over the closed upper lid, now press
the eyeball gently backwards into the orbit, and observe the elastic resistance met
with, due to the fact that the globe rests posteriorly on a pad of fat.
The space between the free edges of the upper and lower lids is known as the
palpebral aperture: it is a mere slit when the lids are closed; but when they are open
its shape is, roughly, that of an almond lying with its long axis horizontal, and
about thirty millimetres in length.
THE EYEBALL AND ITS SURROUNDINGS
875
When the eyes are directed to an object straight in front of them, this aperture
is about twelve millimetres wide, but its width varies with upward and downward
movements of the eyeball, being greatest on looking strongly upwards, diminishing
gradually as the eye looks progressively lower. The angles formed by the meeting of
the lids at each end of the palpebral aperture are named respectively the outer and
inner canthus, of which the outer, or temporal, is sharp, while the inner, or nasal,
is rounded off. On a closer inspection, it will be found that, for the last five milli-
metres or so before reaching the inner canthus, the edges of the lids run an almost
parallel course, and are here devoid of lashes. Through the open palpebral aperture
the front of the eyeball comes into view, extending quite to the outer, but not reach-
ing as far as the inner, canthus; just within the latter we find a small reddish
prominence, the lachrymal caruncle; and between this and the eyeball a fold of
conjunctiva known as the plica semilunaris. While the eye is open, press one
finger on the skin, a little beyond the outer canthus, and draw it firmly outwards
from the middle line; observe that the upper lid then falls over the eyeball, and
that the outline of a firm band already referred to (the tendo oculi) becomes
evident, passing between the inner canthus and the nose. The falling of the lid is
caused by our dragging upon a ligament (the outer palpebral) to which the outer
end of its tarsus is attached, and so putting the lid itself upon the stretch. If,
while the eyeball is directed downwards, we place one finger on the outer end of
the upper eyelid and draw it forcibly upwards and outwards, we can usually cause
the lower division of the lachrymal gland to present just above the outer canthus.
The upper eyelid is much broader than the lower, extending upwards as far as
the eyebrow. The skin covering it is loosely attached to the subjacent tissues above,
but more firmly below, nearer the free margin, where it overlies a firm fibrous
tissue called the tarsus. When the eye is open, a fold is present at the upper border
of this latter more tightly applied portion of skin, called the superior palpebral fold,
and by it the lid is marked off into an upper or orbital, and a lower or tarsal,
division. The presence of the tarsus can be readily appreciated on our pinching
horizontally the entire thickness of the eyelid below the palpebral fold. The lower
eyelid is similarly divided anatomically into a tarsal and an orbital part, but the
demarcation is sometimes unrecognisable on the surface, though there is usually
here also a fold or groove (the inferior palpebral) visible when the eye is widely
opened. There is no precise limit of this lid below, but it may be regarded as
extending to the level of the lower margin of the orbit. Numerous very fine short
hairs are seen on the cutaneous surface of both eyelids. The free margin of each
lid has two edges-(a) An outer, or anterior, rounded edge, along which the stiff
eyelashes, or cilia, are closely placed in several rows; and (b) a sharp posterior edge,
which is applied to the surface of the globe. The lashes of both eyelids have their
points turned away from the palpebral aperture, so that the upper ones curve upwards,
and the lower downwards; the cilia of the upper lid are the stronger, and those in the
middle of each row are longer than those at each end. Between the two edges just
described, the lid-margin has a smooth surface, on which we observe a single row
of minute apertures, which are the openings of large modified sebaceous glands (the
Meibomian follicles); it is by these glistening, well-lubricated surfaces that the
opposite lids come into apposition when they are closed. The sharp posterior edge
of the lid-margin marks the situation of the transition of skin into mucous
membrane. Not far from the inner end of this edge we find a prominence, the
lachrymal papilla, on the summit of which is a small hole (lachrymal punctum),
the opening of the canaliculus for the passage of tears into the lachrymal sac. The
lower punctum is rather larger than the upper, and is placed further from the inner
canthus.
If we now examine the inner surface of the eyelids-e.g. of the lower-we
observe that it is lined by a soft mucous membrane, the palpebral conjunctiva.

876
ORGANS OF SPECIAL SENSE
Over the tarsal part of the lid, the conjunctiva is closely adherent, but beyond this
it is freely movable along with the loose submucous tissue here present. On tracing
it backwards, we find that it covers the whole inner surface of the lids, and is then
continued forwards over the front of the eyeball, forming the ocular conjunctiva;
the bend it makes as it changes its direction here is called the conjunctival cul-de-
sac, or fornix. Numerous underlying blood-vessels are visible through the palpebral
conjunctiva, and beneath the tarsal part of it we can see a series of nearly straight,
parallel, light yellow lines, arranged perpendicularly to the free margin of the lid-
the Meibomian follicles. The conjunctiva over the outer and inner fourths of each
lid is not quite so smooth as elsewhere, and is normally of a deeper red colour;
we shall find later that there are glands well developed in these positions.
When the eyelids are opened naturally, we see through the palpebral aperture
the following: the greater part of the transparent cornea, and behind it the coloured
iris with the pupil in its centre; white sclerotic to the outer and inner sides of the
cornea; the semilunar fold and lachrymal caruncle at the inner canthus. The
extent of the eyeball visible in this way varies according to its position. Thus,
with the eyes looking straight forwards, the lower margin of the upper lid is nearly
opposite to the top of the cornea, or, more strictly, to a line midway between the
FIG. 472.-VIEW OF EYEBALL, ETC., OBTAINED ON DRAWING THE LIDS FORCIBLY APART.
(After Merkel, slightly modified.)

SEMILUNAR FOLD
UPPER LACHRYMAL PUNCTUM
CARUNCLE-
LOWER LACHRYMAL PUNCTUM
OPENINGS OF MEIBOMIAN FOLLICLES
CONJUNCTIVAL FORNIX
top of the cornea and the upper border of the pupil, while the lower lid corresponds
with the lower corneal margin. When the eyes are directed strongly upwards, the
upper lid is relatively on a slightly higher level, as it is simultaneously raised, but
the lower lid now leaves a strip of sclerotic exposed below the cornea. On looking
downwards, the upper lid covers the upper part of the cornea as low down as the
level of the top of the pupil, while the lower lid is about midway between the pupil
and the lower corneal border.
If we draw the eyelids forcibly apart, we expose the whole cornea, and a zone
of sclerotic about eight and a half millimetres in breadth above and below, and ten
millimetres in breadth to the outer and inner sides, altogether about one-third of
the globe; all the eyeball thus exposed is covered by the ocular conjunctiva. Over
the sclerotic the conjunctiva is freely movable, and through it we see superficial
blood-vessels that can be made to slip from side to side along with it (conjunctival
vessels). Occasionally other deeper vessels may also be seen which do not move
with the conjunctiva, but are attached to the sclerotic (anterior ciliary arteries and
veins). Near the corneal border the conjunctiva ceases to be freely movable, and
it is closely adherent to the whole anterior surface of the cornea, giving the latter
its characteristic bright, reflecting appearance; no blood-vessels are visible through
it here in health. (When the lids are shut, the space enclosed between their posterior
THE EYEBALL AND ITS SURROUNDINGS
877
surfaces and the front of the eyeball is thus everywhere covered by conjunctiva,
and is known as the conjunctival sac.)
Not infrequently, the tendinous insertions of some or all of the recti muscles
into the sclerotic may be seen through the conjunctiva, each insertion appearing as
a series of whitish parallel lines running towards, but terminating about seven milli-
metres from the corresponding corneal border. The cornea appears as a transparent
dome, having a curvature greater than that of the sclerotic; the junction of the two
unequally curved surfaces is marked by a shallow depression running around the
cornea, known as the scleral sulcus. In outline the cornea is nearly circular, but its
horizontal diameter is slightly greater than its vertical. Between it and the iris a
space exists, whose depth we can estimate roughly by looking at the eye from one
side; this space, or anterior chamber, is occupied by a clear fluid, the aqueous humour.
Almost the whole anterior surface of the iris is visible, its extreme periphery only
being concealed by sclerotic. In colour the iris varies greatly in different indivi-
duals. Near its centre (really a little up and in) a round hole exists in the iris, the
black pupil, whose size varies considerably in different eyes, and in the same eye
according to temporary conditions, such as exposure to light, etc.
In examining the surface-markings of the living iris, one of dark colour is to be
preferred. Focal illumination will be found useful, for which purpose a second convex
lens will be required.
On the surface of the iris we see a number of ridges running more or less
radially; adjoining ones occasionally unite and interlace to some extent, so as to
leave large depressed meshes at intervals. The ridges coming from the edge of the
pupil, and those coming from the more peripheral part of the iris, meet in a zigzag
elevated ridge, concentric with the pupil, and by this ridge the iris is roughly
marked off into two unequal zones-an outer or ciliary, and an inner or pupillary
-of which the latter is much the narrower. The border next the pupil is edged
with small, roundish, bead-like prominences of a dark brown colour, separated from
one another by depressions, so that it presents a finely notched contour. Not infre-
quently, in a light-coloured iris, we may see the sphincter muscle through the anterior
layers, in the form of a ring about one millimetre in breadth around the pupil.
The ciliary zone may be described as consisting of three parts: (a) A comparatively
smooth zone next the zigzag ridge; (b) a middle area, showing concentric but
incompletely circular furrows; (c) a small peripheral darker part, presenting a
sieve-like appearance.
On the floor of the large depressed meshes, or crypts,
parallel radial vessels can be traced, belonging to the iris-stroma. The zigzag line
mentioned above corresponds to the position of the circulus arteriosus minor.
Occasionally, especially in a light iris, superficial pigment spots of a rusty brown
colour occur.
If we are examining the living eye, the ophthalmoscope should now be used, so as to
gain a view of the fundus. We can thus study the termination of the optic nerve, the
distribution of the larger retinal vessels, etc.

The general red reflex obtained from the fundus is due to the blood in a capillary
network (chorio-capillaris) situated in the inner part of the choroid. To the nasal
side of the centre of the fundus is a paler area of a disc shape corresponding to the
intraocular end of the optic nerve, and known as the optic disc, or papilla. This
optic disc is nearly circular, but usually slightly oval vertically; it is of a light
orange-pink colour, with a characteristic superficial translucency; its outer third
segment is paler than the rest from the nerve-fibres and capillaries here being
fewer. About its centre we often observe a well-marked whitish depression or gap,
formed by the dispersion of the nerve-fibres as they spread out over the fundus; at
the bottom of this depression a sieve-like appearance may be seen, due to the
878
20V ORGANS OF SPECIAL SENSE
presence of the lamina cribrosa, which consists of a white fibrous tissue frame-
work, with small, roundish, light-grey meshes in it, through which latter the nerve-
fibre bundles pass. Also near the centre of the disc, the retinal blood-vessels first
come into view, the arteries narrower in size and lighter in colour than the veins;
they divide dichotomously as they are distributed over the fundus. The retina
proper is so transparent as to be ophthalmoscopically invisible, but its pigment-
epithelium gives a very finely granular or darkly stippled appearance to the general
red reflex. In the centre of the fundus, and therefore to the outer side of the
disc, the ophthalmoscope often shows a shifting halo of light playing round a
horizontally oval, comparatively dark enclosed area; this latter corresponds to the
yellow spot region, and about its centre a small pale spot usually marks the position
of the fovea centralis.
Two structures visible at the nasal end of the palpebral aperture have been
previously mentioned, and should now be examined more narrowly. The
lachrymal caruncle is in reality an island of modified skin, and fine hairs can
commonly be detected on its surface. On its outer side, separated from it by
FIG. 473.-LEFT FUNDUS OCULI, AS SEEN BY DIRECT OPHTHALMOSCOPIC METHOD.
(After Fuchs.)

Retinal artery.
Retinal vein.
LAMINA CRIBROSA
FOVEA CENTRALIS
PIGMENT AT OUTER BORDER OF DISC
a narrow groove, is the semilunar fold of conjunctiva; it rests on the eyeball,
and is a rudiment of the third eyelid or nictitating membrane, present in birds
and well represented in many other vertebrates.
EXAMINATION OF THE EYEBALL
The eyeball of a cadaver should now be removed by snipping with scissors the
conjunctiva near the corneal border, then cutting through the ocular muscles near their
insertion into the globe, and finally dividing the optic nerve close to the sclerotic.
The eyeball is almost spherical, but not perfectly so, mainly because its anterior,
clear, or corneal segment has a greater curvature than the rest of the eye. Con-
sidering it as a globe, however, we speak of an anterior and of a posterior pole; the
former corresponding to the middle of the front of the cornea, the latter to the
middle of the posterior curvature. An imaginary straight line joining the two
poles is called the antero-posterior or sagittal axis of the eyeball. The equator of
the eye is that part of its surface which lies midway between the two poles. The
sagittal axis of the globe is the greatest (about 24.5 mm.), the vertical equatorial
the least (about 23.5 mm.), and the transverse equatorial axis is intermediate in
length (about 23.9), so that the eyeball is in reality an ellipsoid, flattened slightly
from above downwards. Again, if the globe is divided in its antero-posterior vertical


EXAMINATION OF THE EYEBALL
879.
plane, the nasal division will be found to be slightly smaller than the temporal.
The optic nerve joins the globe three or four millimetres to the nasal side of the
posterior pole.
The shape of the eye depends on, and is preserved by, the outermost tunic,
formed conjointly by the cornea and sclerotic, the entire outer surfaces of which
are now in view. The anterior or corneal part has been already examined. All
round the cornea there remains a little adherent conjunctiva; elsewhere, the
sclerotic is directly exposed, except for some loose connective tissue which adheres
to it, especially around the optic nerve entrance. In front of the equator we see
the tendinous insertions of the four recti muscles. Behind the equator are the
insertions of the two oblique muscles-that of the superior oblique tendinous,
and further forwards; that of the inferior more fleshy, and placed between the optic
nerve and the external rectus.
It is difficult to recognise the different recti muscles by their insertions if we do not
know whether the eye examined is a right or left one. To determine this we should hold
the globe with the optic nerve towards us, and in the natural position with the superior
oblique tendon uppermost. The inferior oblique tendon will now poin to the side to
which the eye belongs, and we can consequently determine the different recti muscles.
FIG. 474.-DIAGRAMMATIC VIEW OF THE INSERTIONS OF THE OCULAR MUSCLES.
(After Merkel.)


Inferior rec.
Inferior rec.
External
rec.
nferior obl
Internal rec.
Superior rec.
Superior rec.
Internal/ree.
al ree.
Inferior rec.
Superior
rec.
Superior obl.
External rec.


External rec.
The internal rectus is inserted nearest (7 mm. from) the corneal border; the
external rectus commonly, sometimes the superior, is inserted furthest from it (about
8 mm.). All the recti tendons are broad and thin, but that of the internal is the
broadest (8 mm.); those of the external and inferior the narrowest (6 mm.). The
greatest interval between two neighbouring tendons is that between the superior
and internal recti (about 12 mm.); the least is between the superior and external
(7 mm.). The form of the lines of insertion of the different tendons varies
considerably, the inferior being almost straight, the superior and external convex
forwards, the internal further removed from the corneal border below than above.
The insertions of the obliques are at more than double the average distance of
the insertions of the recti from the corneal border. That of the superior oblique is
found on the superior surface of the sclerotic, about sixteen millimetres from the
corneal edge, in the form of a line sloping from before backwards and inwards.
The inferior oblique has a long fleshy insertion lying between the external rectus
and the optic nerve entrance; the posterior end of the insertion, which is also the
highest, is only about six millimetres from the optic nerve, and from this point
it slopes forwards, outwards, and slightly downwards.


880
ORGANS OF SPECIAL SENSE
Several small nerves and two arteries may be seen running forwards and ulti-.
mately perforating the sclerotic not far from the entrance of the optic nerve. The
two arteries are the long posterior ciliary; they both perforate the globe in the
horizontal meridian, one on the outer, the other on the inner side. The short
ciliary arteries are too small to be seen in an ordinary examination. The nerves
are the long and short ciliary. Nearer the equator, the large venous trunks emerge;
they can be traced for some distance in front of their exit as dark lines, running
antero-posteriorly beneath the sclerotic. The optic nerve is seen in section,
surrounded loosely by a thick outer sheath; in the centre of the nerve-section a
small red spot indicates the position of the central retinal blood-vessels.
For ordinary dissections eyes of the sheep, pig, or bullock should be obtained. Divide
an eyeball into fore and hind halves by cutting through it in the equatorial plane.
1. Posterior hemisphere seen from in front. This is much the same view that the
ophthalmoscope affords us. Unless the eye be very fresh, however, the retina will have
lost its transparency, and will now present the appearance of a thin whitish membrane,
detached in folds from the underlying coats, but still adherent at the optic disc. The
vitreous jelly lying within the retinal cup may be torn away. In the human eye the retina
next the posterior pole is stained yellow (macula lutea). On turning the retina over, a little
pigment may be seen adhering to its outer surface here and there. Cut through the retina
close to the optic disc all round and remove it; note how easily it is torn. We now see a
dark brown surface, consisting of the retinal pigment layer, adherent to the inner surface
of the choroid. Brush off the retinal pigment under water. The choroid thus exposed can
for the most part be fairly easily torn away from the thick sclerotic, as a lymph-space
FIG. 475.-EQUATORIAL SECTION OF EYEBALL: ANTERIOR SEGMENT VIEWED FROM
BEHIND. (After Merkel.)

PUPIL
CILIARY PROCESSES
PLICE CILIARES
LENS
exists between them, but the attachment is firm around the optic nerve entrance, and also
where the arteries and nerves join the choroid after penetrating the sclerotic. The choroid
is darkly pigmented of a brown colour, with markings on its surfaces corresponding to the
distribution of its large veins. The inner surface of the sclerotic is of a light brownish
colour, mainly from the presence of a delicate pigmented layer, the membrana suprachoroidea,
which adheres partly to it, partly to the choroid, giving to their adjacent surfaces a floccu-
lent appearance when examined under water.
2. Anterior hemisphere viewed from behind.-The round opening of the pupil is
visible in the middle, with the large clear crystalline lens lying behind it. The retina
proper extends forwards a little way from our line of section, and then ends abruptly in a
wavy line called the ora serrata, beyond which it is only represented by a very thin
membrane (pars ciliaris retina). Outside the periphery of the lens are a number of
ciliary processes arranged closely together in a circle concentric with the pupil, and each
radially elongated; posteriorly they are continuous with numerous fine folds, also radial,
which soon get very indistinct as they pass backwards, but reach almost to the ora serrata
(plicæ ciliares). Between the front of the ciliary processes and the edge of the pupil lies
the iris. On removal of the retina the inner surface of all this region is seen to be darkly
pigmented, but especially dark in front of the position of the ora serrata. Vitreous probably
still adheres to the back of the lens, and by pulling upon it the lens can be removed along
with its capsule and suspensory ligament; some pigment will now be found adhering to the
front of the vitreous, torn from the ciliary processes, which are consequently now lighter
in colour than before. The lens-capsule is transparent, and has a smooth glistening outer
surface; through it a greyish star-shaped figure may be observed on the anterior and
posterior surfaces of the lens. The suspensory ligament is a transparent membrane attached
to the capsule of the lens about its equator, and is best seen by floating the lens in water
in a glass vessel placed on a dark ground. On opening the capsule we expose the lens
EXAMINATION OF THE EYEBALL
881

itself, which is superficially soft and glutinous to the touch, but becomes firmer as we rub
off its outer layers and approach its centre. Carefully tear the choroid and iris from the
sclerotic: a firm adhesion exists just behind the corneal periphery. Their outer surface thus
exposed is found to be also rather darkly pigmented (as far forward as the base of the iris
at least), but it shows a white ring corresponding to the adhesion just mentioned, and a
pale area behind this ring indicates the position of the ciliary muscle. On this surface
numerous white nerve-cords are visible running forwards. Observe that the iris, the
ciliary processes, etc., and the choroid are all different parts of the same ocular tunic-mere
local modifications of it. Similarly the sclerotic and cornea are seen to blend together to
form one outer coat.
An eyeball should now be placed for half an hour in a freezing mixture of crushed ice
and salt. It will thus become quite hard, and should at once be divided into two parts
by cutting it antero-posteriorly through the centre of the cornea and the optic nerve.
We thus gain another view of the relations of parts, the position of the lens between
the aqueous and vitreous chambers, etc. On removing the lens, vitreous, and retina,
and brushing off its pigment, the light markings corresponding to the choroidal veins
(venæ vorticosæ) should be noted, and their distribution studied. Usually four vortices or
fountain-like markings are found in the whole choroid, their points of junction situated at
approximately equal distances from one another at about the line where the posterior and
middle thirds of the globe meet. These sections should be kept for reference while following
the further description of the ocular tunics.
1. The outer, fibrous coat of the eye is formed by the sclerotic and cornea,
which
pass into one another at the scleral sulcus. It consists throughout mainly
of fine connective-tissue fibres, arranged in interlacing bundles, with small lymph-
spaces at intervals between them. The naked-eye appearance of the two divisions
of this fibrous coat is, however, quite different, the cornea being transparent, while
the sclerotic is white and opaque.
The sclerotic encloses the posterior five-sixths or so of the eyeball, but there is
a hole in it at the entrance of the optic nerve (foramen sclera), only partially
bridged across by fibres from its inner layers forming the lamina cribrosa. The
fibre-bundles composing the sclerotic are arranged more irregularly than in the
cornea, and run mainly in two directions, viz. from before backwards, and
circularly; the circular fibres are particularly well developed just behind the
sulcus. It is thickest (about 1 mm.) posteriorly, where it is strengthened chiefly
by the outer sheath of the optic nerve, and partly also by the tissue surrounding
the ciliary vessels and nerves. It becomes gradually thinner as it passes forwards,
up to the line of insertion of the recti muscles, in front of which line it is again
reinforced by their tendinous fibres becoming incorporated with it. In children
the sclerotic is often so thin as to allow the underlying choroidal pigment to show
through, appearing then of a bluish white. In the aged, again, it is sometimes
yellowish. It always contains a few pigment cells, but these are in the deep layers,
and only become visible externally where the sclerotic is pierced by vessels and
nerves going to the choroid. It is itself almost non-vascular, but quite at its
anterior end a large venous sinus (canal of Schlemm) runs in its deeper layers
circularly around the cornea. Just in front of this sinus, at the corneal limbus,
the sclerotic merges into the cornea, its deeper layers changing first, and finally the
superficial ones.
The cornea is thickest at its periphery, and becomes gradually thinner towards
its centre; the curvature of its posterior is consequently greater than that of
its anterior surface, but even the latter is more curved than the surface of the
sclerotic. In the cornea proper, fibre-bundles are arranged so as to form a series
of superposed lamellæ, each of which is connected here and there to the adjacent
ones by fibres passing from one to the other, so that they can only be torn apart
with difficulty. The corneal lymph-spaces communicate with one another by very
fine canals, and thus not only is a thorough lymph-circulation provided for, but
the protoplasm with which these spaces are partially occupied may be also
regarded as continuous throughout. It contains no blood-vessels, with the exception


3 L
882
ORGANS OF SPECIAL SENSE
of a rich plexus at its extreme periphery, on which its nutrition is ultimately
dependent.
The most superficial part of the true cornea appears homogeneous, even when
highly magnified (Bowman's membrane), though there is reason to believe that its
structure only differs from that already described in the closeness of its fibrous
texture; the two parts are certainly connected by fine fibres. Anteriorly, the cornea
is covered by an extension of the ocular conjunctiva, in the form of an epithelium
several layers deep. Posteriorly, the cornea is lined by a firm, thin, glass-like
layer (membrane of Descemet, posterior elastic lamina), distinct from the corneal
tissue both anatomically and chemically. At the periphery this membrane breaks
up into a number of fibres, which mainly arch over to join the base of the iris
(ligamentum pectinatum iridis). The interstices between these fibres constitute
spaces (spaces of Fontana) freely communicating with the aqueous chamber on the
one hand, and indirectly with the canal of Schlemm on the other. Descemet's
membrane is in turn lined by a single layer of flat cells, which are continuous
peripherally with cells lining the spaces of Fontana and the anterior surface of the
iris. The cornea is richly supplied with nerves, particularly in its most superficial
layers.
2. The dark, middle, or vascular coat of the eye, generally known as the uveal
tract, is formed by the iris, ciliary body, and choroid. It is closely applied to the
sclerotic, but actually joins it only at the anterior and posterior limits of their
course together viz. at the scleral sulcus, and around the optic nerve entrance. In
front of the sulcus the middle coat no longer lines the outer, being separated from
it (i.e. the iris from the cornea) by a considerable space filled with fluid, called the
anterior aqueous chamber. The uveal tract has two openings in it; a larger one
in front, the pupil, and a smaller one behind, for the passage of the optic nerve.
Its structure is that of a pigmented connective tissue, supporting numerous blood-
vessels and containing many nerves and two deposits of smooth muscle-fibres.di
The choroid forms the posterior part of the uveal tract, and extends, with
slowly diminishing thickness, forwards as far as the ora serrata. Its outer and
inner surfaces are both formed by non-vascular layers; that covering the outer, the
membrana suprachoroidea, is pigmented, arranged in several fine loose lamellæ,
and has been seen in our dissection; that covering the inner surface is a thin,
transparent, homogeneous membrane, called the vitreous lamina of the choroid, or
the membrane of Bruch. The intervening choroidal stroma is very rich in blood-
vessels, which are of largest size next its outer surface, and become progressively
smaller as we approach the vitreous lamina, next to which we find a layer of
closely placed wide capillaries, called the chorio-capillaris. The pigment becomes
less in amount as we pass inwards, and finally ceases, being absent entirely from
the chorio-capillaris and vitreous lamina.
In front of the ora serrata the uveal coat becomes considerably modified, and
the part reaching from here to the iris may conveniently be termed the ciliary
region of the tract, or ciliary body. Its superficial aspects have been already
briefly described. In front, the ciliary processes, about seventy in number, project
towards the interior of the eye, forming the corona ciliaris. Behind this part lies the
orbiculus ciliaris, whose inner surface is almost smooth, faint radial folds only
being present, three or four of which join each ciliary process. The more minute
structure of this ciliary region resembles closely that of the choroid, except that
the chorio-capillaris is no longer present, that the stroma is thicker and richer in
blood-vessels, and that a muscular element (ciliary muscle) exists between the
vascular layer and the membrana suprachoroidea. On antero-posterior section the
ciliary body is triangular; the shortest side looks forward, and from about its middle
the iris arises; the two long sides look respectively inwards and outwards, the inner
having the ciliary processes upon it, while the outer is formed by the ciliary muscle.



EXAMINATION OF THE EYEBALL
883
This muscle possesses smooth fibres and consists of an outer and inner division;
in the outer the fibres run longitudinally, inserted into the outer fibrous coat of
the eye at the sclero-corneal junction in front, and passing backwards to join the
outer layers of the orbiculus and choroid; the inner contains circularly running
fibres situated next to the ciliary processes. The entire muscle is destitute of
pigment, and therefore is recognisable in the section by its light colour. The
whole thickening of the uveal tract in this region, muscle and folds and processes
together, is named the ciliary body.
The iris projects into the interior of the front half of the eye in the form of a
circular disc perforated in the middle. The appearance of its anterior surface has
FIG. 476.-DIAGRAMMATIC HORIZONTAL SECTION OF EYEBALL AND ORBIT.
(After Fuchs, much modified.)
Periorbita green; muscle-fascia red; Tenon's capsule yellow.
Lower lachrymal punctum
Cornea
Opening of Meibomian gland
Anterior chamber
Iris.
Corona ciliaris.
Orbiculus ciliaris
Choroid with
vence vorticosce g
Outer check ligament
Fovea centralis retinc
Muscle-fascia
Orbital blood-vessel
Central retinal vessels
in optic nerve
External rectus
muscle
CARUNCLE
Inner palpebral ligament
NASAL PROCESS OF UPPER JAW
Anterior limb of inner palpebral
ligament
Lachrymal sac
Posterior limb of inner palpebral
ligament with Horner's muscle
springing from it
LACHRYMAL BONE
Process of muscle-fascia to under
surface of conjunctiva
Ora serrata
Tendon of insertion of internal
rectus
Inner check ligament
Periorbita
ORBITAL PLATE OF ETHMOID BONE
Posterior lamina of muscle-fascia
lined by Tenon's capsule
Internal rectus muscle
-OPTIC NERVE
already been described. Its posterior surface exhibits numerous radial folds
running from the ciliary processes to near the pupillary border; a thick layer of black
pigment covers it and curls round its inner edge, so as to come into view all round
the pupil as seen from in front. The peripheral or ciliary border of the iris is
continuous with the front of the ciliary body, where it also receives fibres from the
ligamentum pectinatum iridis; in other respects the iris is quite free, merely resting
on the front of the lens-capsule near the pupil. Its stroma is spongy in character,
being made up of vessels covered by a thick adventitia, running from the periphery
to the pupillary border, with interspaces filled by branching pigment cells, which
are particularly abundant near the front surface. Deep in the stroma, running
3L2
884
ORGANS OF SPECIAL SENSE
round near the pupillary border, we find a broad flat band of smooth muscle fibres,
constituting the sphincter iridis. Immediately behind the vascular tissue lies a thin
membrane, consisting of fine, straight fibres running radially from the ciliary
border to just behind the sphincter. These fibres are often described as muscular,
but in the absence of satisfactory evidence of their being of this nature, they are
better regarded as elastic, the whole membrane serving to dilate the pupil on
relaxation of the sphincter.
Among mammals, radial muscle-fibres are present in the iris of the otter, and probably
also in that of the rabbit; in all the others examined their existence is very doubtful. In
birds the muscular system of the iris is of the striped variety, and many of the fibres
certainly run radially, so that the possibility of a muscular dilating action is provided for.
The sphincter iridis and the ciliary muscle are supplied by the third nerve, by
way of the ciliary ganglion.
Quite posteriorly is the pigment already mentioned, really consisting of two
layers of pigmented cells, each layer representing the extension forward of one
subdivision of the retina. The front of the iris is covered by a delicate epithelial
layer, a continuation of that lining Descemet's membrane. The colour of the
iris in different individuals depends upon the amount of stromal pigment.
3. The innermost or nervous coat.-The inner surface of the uveal tract is
everywhere lined by a layer of pigment of corresponding extent, which usually
adheres to it closely on dissection. Developmentally, however, this general pigment
lining is quite distinct from the uveal coat, and represents the outer wall of the
secondary optic vesicle or embryonic retina: it consists of a single layer of
pigmented epithelial cells. The amount of pigment is greatest anteriorly, over
the ciliary region and iris, and there is again a small local increase posteriorly,
corresponding to the macula lutea and to the edge of the optic foramen. In the
ciliary region these cells have recently been described as lining numerous narrow
tubular depressions in the inner part of the uveal tract, and they seem here to
have a special function, viz. that of secreting the intraocular fluids.
From the manner in which the secondary optic vesicle, or optic cup, is formed,
its two walls are necessarily continuous in front, at what may be termed the lip of
the cup: we have just observed that the outer wall lines the uveal coat everywhere
and corresponds in extent; consequently, the lip must be looked for at the edge of
the pupil, i.e. at the termination of this coat anteriorly. The inner wall of the cup,
consequently, reaches from the lip, or pupillary edge, in front, to the optic stalk or
nerve behind, and is in close apposition to the pigment-epithelium; unlike the outer,
however, this wall is represented in the developed eye by tissues very dissimilar in
structure in different parts of its extent. Tracing it backwards from the pupillary
edge, we find that over the whole posterior surface of the iris it exists as a single
layer of pigmented epithelium, the developmental changes having here produced a
result similar to what we have found throughout in the outer wall: here, accordingly,
we have a double layer of pigment cells. At the root of the iris the single inner layer
of cells still exists; but now they become destitute of pigment, and this condition
obtains over the entire ciliary region, constituting what is known as the pars
ciliaris retinæ. At the line of the ora serrata the tissue derived from the inner wall
abruptly increases in thickness, and rapidly acquires that complexity of structure
characteristic of the retina proper, which extends from here to the optic nerve.
consists of several layers-nerve-fibres, nerve-cells, and nerve-epithelium-held
together by a supporting framework of delicate connective tissue. The nerve-
epithelium is on the outer surface, immediately applied to the pigment-epithelium;
at the posterior pole of the eye a small spot (fovea centralis) exists, where this is
the only retinal layer represented, and where consequently the retina is extremely
thin. The nerve-fibres run on the inner surface of the retina and are continuous

It
EXAMINATION OF THE EYEBALL
885
with those of the optic nerve; they constitute the only retinal layer that is continued
into the intraocular end of the nerve. The nerve-cells are found between these
surface layers. The larger blood-vessels of the retina run in the inner layers, and
none encroach on the layer of nerve-epithelium.
Within the coats mentioned, the interior of the eyeball is fully occupied
by contents, which are divided into three parts, and differently named according to
their consistence and anatomical form. They are all transparent, as through them
the light has to pass so as to gain the retina. Of these the only one that is
sharply and independently outlined is the lens, which is situated in the anterior
half of the globe at the level of the ciliary processes, where it is suspended between
the other contents, which fill respectively the space in front of it and the space
behind it. The space in front is called the anterior or aqueous chamber; that
behind the lens is the vitreous chamber.
FIG. 477.-SEMI-DIAGRAMMATIC HORIZONTAL SECTION THROUGH EYEBALL AND OPTIC
NERVE. (After Elfinger. Reduced and altered.)

Corneal epithelium
CORNEA
ANTERIOR AQUEOUS
CHAMBER
CANAL OF SCHLEMM
POSTERIOR
AQUEOUS
CHAMBER
CANAL OF PETIT
Internal
rectus
muscle
IRIS
LENS
VITREOUS
CHOROID
RETINA
doleyd)
Biolayd
Central retinal vessels
OPTIC NERVE-
SUBSTANCE
PIAL NERVE-
SHEATH
DURAL NERVE-SHEATH
Ciliary muscle
CONJUNCTIVA
SCLEROTIC
(covered exter-
nally by Tenon's
capsule and
loose tissue)
The lens is a biconvex body, with its surfaces directed anteriorly and posteriorly;
these surfaces meet at its rounded-off edge or equator, which is near (but does not
touch) the ciliary processes all round. The posterior is considerably more convex than
the anterior surface; the central part of each surface is called its pole. The lens
is closely encased in a hyaline elastic capsule, thicker over the anterior than over
the posterior surface. Thus enclosed, it is held in position in the globe by a
suspensory ligament, attached to its capsule near the equator all round, and swung
from the ciliary region. Posteriorly, the lens rests in a cup formed by the front part
of the vitreous, while its anterior capsule is in contact with the aqueous fluid and lies
close against the back of the pupillary border of the iris. When in position the lens
measures nine millimetres across, and about four millimetres between its poles. On
886
ORGANS OF SPECIAL SENSE
each surface a series of fine, sinuous, grey lines can be seen radiating from the pole
towards the equator, called respectively the anterior and posterior stellate figures.
The lines observable on the posterior are always so placed as to be intermediate with
those on the anterior surface, so that on viewing them through the lens they occupy
a position corresponding to the intervals between the lines on the anterior surface.
The lens-capsule is comparatively brittle, and can be readily cut through when
scraped with a sharp-pointed instrument; on doing so the divided edges curl
outwards, away from the lenticular substance. When removed from its capsule,
the outer portion of the lens is found to be soft and glutinous, but its substance
gets progressively firmer as we approach the centre. This harder central part is
known as the nucleus, and the surrounding softer matter as cortex. The cortical
part shows a tendency to peel off in successive layers. It consists of long fibres,
the ends of which meet in front and behind at the anterior and posterior stellate
figures.
Histologically the capsule is not in immediate contact with the cortex over the front
surface of the lens, a single layer of cells intervening, called the subcapsular epithelium.
The suspensory ligament of the lens is formed by a thickening of the anterior
part of a membrane enclosing the vitreous, strengthened by numerous fibres
derived from the folds of the ciliary region. Its chief attachments to the lens-
capsule are a little in front of and behind the equator, and the space included
between the most anterior and most posterior divisions of the ligament is termed
the canal of Petit. This space is bridged across by fine intermediate suspensory
fibres, and is occupied by fluid.
The vitreous humour is a transparent, colourless, jelly-like mass, enclosed in a
delicate, clear, structureless membrane, called the hyaloid membrane. This latter
is closely applied to the back of the posterior lens-capsule and of the suspensory
ligament, and to the inner surface of the pars ciliaris retinæ, retina proper, and
optic papilla. Although possessing some degree of firmness, the vitreous humour
contains quite 98 per cent. of water, and has no definite structure. Membranes
have been described in it, but these are really artificial products. In certain
situations spaces exist in the vitreous mass, the most determinate of which runs in
the form of a canal from the optic papilla to the posterior pole of the lens, corre-
sponding to the position of the foetal hyaloid artery (hyaloid canal, or canal of
Cloquet). Other very fine spaces are described running circularly in the peripheral
part of the vitreous concentric with its outer surface. Microscopically, wandering
cells are found in the vitreous, which often here assume peculiar forms which the
observer can, not infrequently, study subjectively.
The aqueous humour is a clear, watery fluid, occupying the space between
the cornea on the one hand, and the ciliary body, suspensory ligament, and lens on
the other. The iris, projecting into this space, has both its surfaces bathed in the
aqueous; but, as its inner part rests on the lens, it is regarded as dividing the
space into two parts, an anterior larger, and a posterior smaller aqueous chamber,
which communicate freely through the pupil.
Ciliary nerves of the eyeball.-The long and short ciliary nerves, after per-
forating the sclerotic, run forward between it and the choroid to the ciliary region,
where they form a plexus, from which proceed branches for the ciliary muscle, the
iris, and the cornea. The nerves of the iris enter it at its ciliary border, and run
towards its pupillary edge, losing their medullary sheath sooner or later, and
supplying specially the sphincter muscle. The corneal nerves form an annular
plexus near the limbus, from which a few twigs proceed to the sclerotic and con-
junctiva, while most of the offsets enter and run radially in the corneal stroma,
branching and anastomosing so as to form a plexus. The nerves entering the cornea

EXAMINATION OF THE EYEBALL
887
are about sixty in number, each containing from two to twelve non-medullated
nerve-fibres (page 797).
Blood-vessels of the eyeball.-The ocular tissues receive blood from two sets
of vessels, viz. the retinal and the ciliary arteries.
1. The arteria centralis retinæ either comes direct from the ophthalmic artery,
or from one of its branches near the apex of the orbit. Entering the optic nerve
twenty millimetres or less behind the globe, it runs forward in its axis to the end of
the nerve-trunk, and then divides into branches which run in the inner layers of the
FIG. 478.-DIAGRAMMATIC REPRESENTATION OF THE BLOOD-VESSELS OF THE EYEBALL.
(Leber.)
Arteries red; veins blue.
Canal of Schlemm and con-
nections with anterior
ciliary vein
Branch from ciliary body to
anterior ciliary vein
Vessels of ciliary processes
Vein from iris and ciliary
body to vena vorticosa
A exia la
Recurrent choroidal artery
Branch from short posterior
ciliary artery to optic nerve
Short posterior ciliary artery.
Vena centralis retina
Marginal corneal plexus
Anterior conjunctival vein
Circulus iridis major
Posterior conjunctival vein
Anterior ciliary vein
Posterior conjunctival
artery
-Anterior ciliary artery
Chorio-capillaris
Episcleral vein
Episcleral artery
Chorio-capillaris
Vena vorticosa
Posterior long ciliary artery
Posterior short ciliary arteries
Vessels of pial sheath of optic nerve
Vessels of dural sheath
Arteria centralis retince
retina, and divide dichotomously as they radiate towards the equator. The smaller
branches lie more deeply in the retina, but none penetrate into the nerve-epithelium,
so that the fovea centralis is non-vascular. In the retina, the branches of the
central artery do not communicate with any other arteries, but while still in the
optic nerve fine communications take place between this artery and neighbouring
vessels. Thus (a) minute twigs from it, which help to nourish the axial part of
the nerve, communicate with those running in the septa derived from the pial sheath.
Again, as the nerve passes through the sclerotic, it is surrounded by a vascular ring

888
ORGANS OF SPECIAL SENSES
(circle of Haller), formed of fine branches derived from the short posterior ciliary
arteries; fine twigs passing inwards from this ring to the optic nerve, join the vessels
of the pial sheath, and (b) an indirect communication is thus brought about between
the retinal and ciliary vessels. Finally, as the nerve passes through the choroid, there
is (c) a direct connection between these two sets of vessels, the capillary network of
the optic nerve being here continuous with the chorio-capillaris. Not infrequently,
a branch from a short posterior ciliary artery pierces the optic papilla, and then
courses over the adjoining retina (a cilio-retinal artery), supplying the latter in part
in place of the central artery.
The vena centralis retinæ returns the blood of the corresponding artery.
2. The ciliary system of blood-vessels (pages 531, 532, and 664). There are
three sets of arteries belonging to this system, all derived directly or indirectly
from the ophthalmic artery.
(1) Short posterior ciliary arteries, twelve to twenty in number, pierce the
sclerotic round the optic nerve entrance, and are distributed in the choroid.
Before entering the eyeball, small twigs are given off to the adjoining sclerotic and
to the dural sheath of the optic nerve.
FIG. 479.-SURFACE OF CHOROID AND IRIS EXPOSED BY REMOVAL OF SCLEROTIC AND
CORNEA, SHOWING DISTRIBUTION OF BLOOD-VESSELS AND NERVES.
(Twice natural size. After Zinn.)
IRIS
A CILIARY NERVE.
SURFACE OF CHOROID IN
CILIARY REGION
A CILIARY NERVE
Long posterior ciliary
artery
FLAP OF SCLEROTIC,
REFLECTED
(2) Two long posterior ciliary arteries, piercing the sclerotic further from the
nerve than the short ciliaries, run horizontally forwards between the sclerotic and
choroid, one on each side of the globe. On arriving at the ciliary body, they
join with the anterior ciliary arteries, forming the circulus iridis major, which
sends off branches to the ciliary processes and the iris. The long ciliaries also
give twigs to the ciliary muscle, and small recurrent branches run backwards to
anastomose with the short ciliary arteries. The arteries of the iris run radially to
the pupillary border, anastomosing with one another opposite the outer border of
the sphincter so as to form the circulus iridis minor.
(3) The anterior ciliary arteries come from the arteries of the four recti
muscles, one or two from each; they run forwards, branching as they go, and
finally pierce the sclerotic near the corneal border. Outside the globe they send
twigs to the adjoining sclerotic, to the conjunctiva, and to the border of the cornea.
After passing through the sclerotic the arteries enter the ciliary muscle, where they
end in twigs to the muscle and to the circulus iridis major, and recurrent branches
to the choroid.

EXAMINATION OF THE EYEBALL
889
Veins. The venous blood from almost the whole uveal tract (choroid, ciliary
processes and iris, and part of the ciliary muscle) ultimately leaves the eyeball by
(1) the venæ vorticosæ, which have been already noticed in describing an antero-
posterior section through the globe. One large vein passes backwards from each
vortex, piercing the sclerotic obliquely; it is joined by small episcleral veins when
outside the globe.
(2) The anterior ciliary veins commence by the junction of a few small veins of
the ciliary muscle; they pass outwards through the sclerotic near the corneal
border, receiving blood from the veins in connection with Schlemm's canal, and
afterwards from episcleral and conjunctival veins, and from the marginal corneal
plexus. Finally they join the veins running in the recti muscles.
Lymphatic system of the eyeball.-Apart from those in the conjunctiva there
are no lymphatic vessels in the eyeball, but the fluid is contained in spaces of
various sizes. These are usually divided into an anterior and posterior set.
FIG. 480.-THE LYMPHATICS OF THE EYEBALL. (Diagrammatic. After Fuchs.)
Anterior ciliary vein
CANAL OF SCHLEMM
PROLONGATION OF TENON'S
CAPSULE ON TENDONS
PERICHOROIDAL SPACE
HYALOID CANAL
SPACE ROUND VENA
VORTICOSA COMMUNICATING
WITH THE PERICHOROIDAL
SPACE AND TENON'S SPACE
TENON'S SPACE
SUPRAVAGINAL SPACE
INTERVAGINAL SPACE
1. Anteriorly, we have the anterior and posterior aqueous chambers, which
communicate freely through the pupil. The aqueous humour is secreted in the
posterior of these chambers, from the vessels of the ciliary body and posterior
surface of the iris (see also page 884). The stream passes mainly forwards through
the pupil into the anterior aqueous chamber, whence it escapes slowly by passing
through the spaces of Fontana into Schlemm's canal, and thence into the anterior
ciliary veins. Part of the lymph-stream passes from the posterior aqueous chamber
backwards into the canal of Petit, out of which fluid can pass into the lens
substance, or diffuse itself into the front of the vitreous.
In the cornea the lymph travels in the spaces already mentioned as existing
between the fibre-bundles, and in the nerve-channels, and at the periphery of the
cornea it flows off into the lymphatic vessels of the conjunctiva.
890
ORGANS OF SPECIAL SENSE
In the iris there is a system of lymphatic spaces opening anteriorly on its
free surface by the crypts previously described, and communicating peripherally
with the spaces of Fontana.
2. Posteriorly, we have (a) the central or hyaloid canal, between the poste-
rior pole of the lens and the optic nerve entrance, and (b) the perivascular canals
of the retina; the lymph from both of these situations flows into the spaces of the
optic nerve, which communicate with the intervaginal space of the nerve, and thus
with the great intracranial spaces. Further, between choroid and sclerotic, we
have (c) the perichoroidal space, which gets the lymph from the choroid, and
communicates with Tenon's space outside the sclerotic by the perforations corre-
sponding to the vasa vorticosa and posterior ciliary artéries, and with the interva-
ginal space around the optic nerve entrance. Tenon's space, again, is continuous
with the supravaginal space around the optic nerve, which communicates both
with the intervaginal spaces, with the lymph spaces of the orbit, and directly with the
intracranial spaces at the apex of the orbit.
FIG. 481.-LEFT EYEBALL SEEN IN ITS NORMAL POSITION IN THE ORBIT, WITH
VIEW OF THE OCULAR MUSCLES. (After Merkel, modified.)
Tendon of superior oblique

Trochlea
Internal rectus
Levator palpebræ
superioris, cut
Superior rectus
External rectus
Inferior rectus
Inferior oblique muscle
30/32
2012 JUS
CAVITY OF THE ORBIT
GENERAL ARRANGEMENT OF ITS CONTENTS
The anterior wider half of the cavity is mainly occupied by the eyeball, which
lies almost axially, but is rather nearer to the upper and outer than it is to the
other walls. The posterior two-thirds of the globe are in relation with soft parts,
chiefly muscles and fat, and its posterior pole is situated midway between the base (or
opening) and the apex of the orbital cavity. The anterior third of the eyeball is
naturally free, except for a thin covering of conjunctiva, and projects slightly beyond
the opening of the orbit, the degree of prominence varying with the amount of orbital
fat, and also to some extent with the length of the globe. A straight line joining the
inner and outer orbital margins usually cuts the eye behind the cornea-externally
behind the ora serrata, nasally further forward, at the junction of the ciliary body and
iris. The globe is held in position by numerous bands of connective tissue. The


CAVITY OF THE ORBIT
891
lachrymal gland lies under the outer part of the roof of the orbit anteriorly. The
orbital fat occupies the spaces between the orbital muscles, and is in greatest amount
immediately behind the eyeball; it also exists between the muscles and the orbital
walls in the anterior half of the cavity. Six muscles, viz. the four recti, the superior
oblique, and the levator palpebræ superioris, arise at the apex of the orbit, and
diverge as they pass forwards. The recti muscles-superior, inferior, external, and
internal-run each near the corresponding orbital wall, but the superior is over-
lapped in part by the levator palpebræ. The superior oblique lies about midway
betweeen the superior and internal recti. A seventh muscle, the inferior oblique,
has a short course entirely in the anterior part of the orbit, coming from its inner
wall and passing beneath the globe between the termination of the inferior rectus
and the orbital floor. The optic nerve with its sheaths passes from the optic
FIG. 482.-SECTION THROUGH CONTENTS OF RIGHT ORBIT 8-11 MM. BEHIND THE EYEBALL,
VIEWED FROM BEHIND. (After Lange.emm
SUPRAORBITAL
NERVE
Supraorbital artery
Levator palpebræ
superioris muscle
Superior
rectus muscle
Superior-
oblique
muscle
NASO-
CILIARY
NERVES
Internal
rectus
muscle
Naso-frontal-
artery
OPTIC NERVE
Ciliary artery
Central retinal
artery
Ciliary artery
Inferior rectus-
muscle
LACHRYMAL
NERVE
-Lachrymal artery
Lachrymal vein
-Ophthalmic vein
Ciliary artery
External rectus
muscle
Ciliary artery
THIRD NERVE
(BRANCH TO
INFERIOR
OBLIQUE
MUSCLE)
foramen to the back of the eyeball, surrounded by the orbital fat, and more imme-
diately by a loose connective tissue. Among the contents of the cavity are also to
be enumerated many vessels and nerves, and fibrous tissue septa, while its walls
are clothed by periosteum (periorbita).
The muscles of the orbit are seven in number, of which six are ocular, i.e. are
inserted into the eyeball and rotate it in different directions. These ocular muscles
are arranged in opponent pairs, viz. superior and inferior recti, superior and
inferior obliques, external and internal recti. With the exception of the short
inferior oblique, they all arise from the back of the orbit along with the seventh
orbital muscle, the elevator of the upper lid. All these long muscles take their
origin from the periosteum in the vicinity of the optic foramen. The four recti
muscles arise from a fibrous ring which arches close over the upper and inner edge
892
ORGANS OF SPECIAL SENSE
of the foramen, and extends down and out so as to embrace part of the opening of
the sphenoidal fissure. Their origins may be said at first to form a short, common,
tendinous tube, from which the individual muscles soon separate, taking the posi-
tions indicated by their respective names.
The external rectus has two origins
from bone, one on either side of the sphenoidal fissure. But in the fresh state the
fissure is here bridged across by fibrous tissue, from which this rectus also springs,
so that its origin is in reality continuous. The part of this fibrous ring nearest
the foramen (corresponding to the origins of the superior and internal recti) is
closely connected with the outer sheath of the optic nerve. The remaining two
long muscles arise just outside the upper and inner part of the above-mentioned
ring, and are often partially united; the levator palpebræ tendon is in close relation
to the origin of the superior rectus, while the superior oblique arises from the
periosteum of the body of the sphenoid bone one or two millimetres in front of
the origin of the internal rectus.
The four recti muscles lie rather close to the corresponding orbital walls for the
first half of their course, the superior rectus, however, being overlapped in part by
the levator palpebræ; they then turn towards the eyeball, running obliquely
through the orbital fat, and are finally inserted by broad, thin tendons into the
sclerotic in front of the equator. The thickest of these muscles is the internal
rectus, next the external, then the inferior, and the superior rectus is the thinnest.
FIG. 483.-DIAGRAMMATIC REPRESENTATION OF ORIGINS OF OCULAR MUSCLES AT THE
APEX OF THE RIGHT ORBIT.
(After Schwalbe, slightly altered.)

Superior rectus
FOURTH NERVE
Levator palpebræ superioris
Lachrymal and frontal vein
Origin of external rectus from fibrous-
bridge over sphenoidal fissure
Naso-ciliary of fifth nerve-
-Superior oblique
-OPTIC FORAMEN AND NERVE
Internal rectus
SIXTH NERVE
Inferior rectus
External rectus
THIRD NERVE
As regards length, the muscular belly of the superior rectus has the longest course,
and the others diminish in the order-internal, external, and inferior rectus. The
external rectus is supplied by the sixth nerve. The other three recti muscles are
all supplied by the third nerve.
The levator palpebræ superioris courses along the roof of the orbit close to the
periosteum for the greater part of its course, partially overlapping the superior
rectus; it finally descends through the orbital fat, and widens out to be inserted
into the root of the upper lid. It may be briefly described as being inserted in two
distinct layers separated by a horizontal interval. The upper or anterior layer of
insertion is fibrous, and passes in front of the tarsus, where it comes into relation
with fibres of the orbicularis. The lower layer consists of smooth muscle (Müller's
superior palpebral muscle) and is inserted along the upper border of the tarsus.
The levator has also connections with the sheath of the superior rectus. These
different insertions of the muscle will be referred to later along with the description
of the orbital fascia and of the upper eyelid. It gets its nervous supply from the
third nerve, but the smooth muscle developed in its lower layer of insertion is
supplied by the sympathetic nervous system. As its name expresses, its action is
to raise the upper lid and to support it while the
eye is

open.
The superior oblique runs forward close to the inner part of the orbital roof
until it reaches the fossa trochlearis near the internal angular process, where it
NERVE-SUPPLY AND ACTION OF MUSCLES
893
becomes tendinous and passes through a fibro-cartilaginous pulley attached to the
fossa just named. On passing through this pulley, or trochlea, the tendon bends at
an angle of 50°, running backwards and outwards under the superior rectus to
its insertion into the sclerotic. It is supplied by the fourth nerve.
It
The inferior oblique arises from the front of the orbit, about the junction of its
inner and lower walls, just external to the lower end of the lachrymal groove.
runs, in a sloping direction, outwards and backwards, lying at first between the
inferior rectus and the orbital floor, then between the external rectus and the
globe; finally it ascends slightly, to be inserted by a short tendon into the sclerotic
at the back of the eye. Its nervous supply is derived from the third nerve. The
precise manner of insertion of the different ocular muscles has been described
above in our EXAMINATION OF THE EYEBALL. (For MUSCLES OF THE EYELIDS
AND EYEBROWs, see pages 455 and following.)
Action of the ocular muscles. While rotating the globe so that the cornea is
turned in different directions, the ocular muscles do not alter the position of the
eyeball in the orbit either laterally, vertically, or antero-posteriorly. In speaking,
therefore, of the eye being moved upwards, or outwards, etc., it is the altered
position of the cornea or front of the eye that we mean to express; it is manifest
that, if the cornea moves up, the back of the eyeball must simultaneously be
depressed, and similarly with other movements. All the movements of the globe
take place by rotation, on axes passing through the centre. Though the possible
axes are numerous in combined muscular action, there are three principal axes of
rotation of the eyeball, and in reference to these the action of individual muscles
must be described. Two of these axes are horizontal, and one vertical; they all
pass through the centre of rotation at right angles to one another. By rotation of
the eye on its vertical axis the cornea is moved outwards (towards the temple), and
inwards (towards the nose): movements called respectively abduction and adduction.
In upward and downward movements of the cornea, the eye rotates on its hori-
zontal equatorial axis. The other principal axis of rotation is the sagittal, which
we have previously described as corresponding to the line joining the anterior
and posterior poles of the globe (page 878). In rotation of the eye on its sagittal
axis, therefore, the cornea may be said to move as a wheel on its axle, for its centre
now corresponds to one end of the axis; in other words, this is a rotation of the
cornea. Such movements may, consequently, be expressed with reference to their
effect on an imaginary spoke of the corneal wheel-e.g. one running vertically
upwards from the corneal centre. Thus we may say rotation of the cornea
outwards' when this part of the wheel moves towards the outer canthus, or
'inwards' when towards the nose.
'

The only two muscles that rotate the eyeball merely on one axis are the
external rectus and the internal rectus; the former abducting, and the latter
adducting the cornea.
The chief action of the superior rectus is to draw the cornea upwards, but at
the same time it adducts and rotates the cornea inwards.
The inferior rectus mainly draws the cornea downwards, also adducting it
and rotating it outwards.
The chief action of the superior oblique is to rotate the cornea inwards, also
drawing it downwards and slightly abducting it.
The inferior oblique mainly rotates the cornea outwards, also drawing it
upwards and slightly abducting it.
The fascia of the orbit. The orbital contents are bound together and supported
by fibrous tissues, which are connected with each other, but which may conveniently
be regarded as belonging to three systems. These are: (1) Those lining the
bony walls; (2) those ensheathing the muscles; and (3) the tissue which partially
encapsules the eyeball.
894
ORGANS OF SPECIAL SENSE
1. The orbital periosteum, or periorbita, is closely applied to the bones forming
the walls of the cavity, but may be stripped off with comparative ease. It presents
openings for the passage of vessels and nerves entering and leaving the orbit.
Posteriorly this tissue is very firm, being joined by processes of the dura mater at
the optic canal and sphenoidal fissure; at the optic foramen it is also connected with
the dural sheath of the optic nerve. As it covers the spheno-maxillary fissure its
fibres are interwoven with smooth muscle, forming the orbital muscle of Müller.
From its inner surface processes run into the orbital cavity, separating the fat
lobules. One important process comes from the periorbita about midway along
the roof of the orbit, runs forward to the back of the upper division of the lachrymal
gland, and there splits, helping to form the gland-capsule: this capsule is joined
at its inner border by other periorbital bands coming off near the upper orbital rim,
and forming the suspensory ligament of the gland. On the inner side of the orbit
FIG. 484.-VIEW OF LEFT ORBIT FROM ABOVE, SHOWING THE OCULAR MUSCLES.
(From Hirschfeld and Leveillé.)

-Levator palpebræ
superioris muscle, cut
External rectus muscle
Internal rectus muscle-
Inferior oblique muscle
Superior oblique muscle
Superior rectus muscle
Trochlea
Levator palpebræ
superioris muscle, cut

the periorbita sends fibrous processes to the trochlea of the superior oblique, which
keep it in position. On arriving at the lachrymal groove the periorbita divides into
two layers, a thin posterior one continuing to line the bone forming the floor of the
groove, whilst the thicker anterior layer bridges over the groove and the sac which
lies in it, forming the limbs of the inner palpebral ligament (page 904).
Quite anteriorly, at the rim of the orbit, the periorbita sends off a membranous
process which aids in forming the fibrous tissue of the eyelids (orbito-tarsal liga-
ment, or palpebral fascia), and is itself continuous with the periosteum of the bones
outside the orbital margin.
2. The orbital muscles are connected by a common fascia, which splits at their
borders and furnishes a sheath to each. Processes of this fascia give membranous
investments for the vessels and nerves (including the optic nerve), splitting similarly
to enclose them; these membranous processes also assist in separating the fat
lobules. Posteriorly, this fascia is thin and loose, and blends with the periorbita at
the origin of the muscles. Anteriorly, it becomes thicker and firmer, accompanies
the muscles to near the equator of the eyeball, and there divides into two laminæ,


CAVITY OF THE ORBIT
895
an anterior and a posterior; the former continues a forward course, forming a
complete funnel-shaped investment all round, passing ultimately to the eyelids and
orbital margin-whilst the latter turns backwards, covering the hinder third of the
globe.
The anterior lamina is a well-marked membrane everywhere, but in certain
situations it presents special bands of thickening, corresponding to the direct
continuation forwards of the sheath of each rectus muscle. Above and below, this
lamina spreads out in the form of two large membranes, which are finally applied
to the deep surface of the palpebral fascia; the lower membrane constitutes what
has been described as 'the suspensory ligament of the eyeball.' The upper mem-
FIG. 485.-VERTICAL SECTION THROUGH THE EYEBALL AND ORBIT IN THE DIRECTION OF
THE ORBITAL AXIS, WITH CLOSED EYELIDS.
(Semi-diagrammatic. After Schwalbe, modified to show fascia.)
Periorbita green; muscle-fascia red; Tenon's capsule yellow.
SKIN OF LOWER LID
LOWER TARSUS
Palpebral fascia and ant.
lamina of muscle-fascia
Orbicularis palpebrarum-
Extension of sheath of
inferior rectus to lower eyelid
FORNIX CONJUNCTIVE
Inferior oblique muscle,
cut across
LENS
VITREOUS
SKIN OF UPPER LID
LUPPER TARSUS
CORNEA
Orbicularis palpebrarum
UPPER RIM OF ORBIT, WITH
Splitting of periorbita
Upper or anterior insertion of
levator palpebræ
Superior palpebral muscle of Müller
FORNIX CONJUNCTIVE
Connection between levator pal-
pebræ and superior rectus, and
fibres to conjunctiva
PROCESS FROM PERIORBITA TO CAPSULE OF
LACHRYMAL GLAND
PERIORBITA
Posterior lamina of
muscle-fascia
SUPRAVAGINAL SPACE CONTINUOUS WITH
TENON'S SPACE
SPACE OCCUPIED BY ORBITAL FAT, PRO-
CESSES OF FASCIA SEPARATING THE
LOBULES AND ENCLOSING BLOOD-VESSELS
Inferior rectus
Superior rectus
Levator palpebræ superioris
-Posterior lamina of muscle-fascia
lined by prolongation of Tenon's
capsule
OPTIC NERVE
brane requires a fuller description, as its distribution is modified by the presence
of the levator palpebræ muscle.
The upper part of the sheath of the superior rectus (along with the adjoining
membrane on each side of it) passes to the deep surface of the levator, to which it
closely adheres, and completely ensheaths this tendon by extending round its borders
to its upper surface. The lower part of this levator-sheath is applied to the inferior
surface of the deeper of the two divisions of the muscle (orbito-palpebral muscle of
Sappey, superior palpebral muscle of Müller), and is attached to the upper border
of the tarsus of the upper lid, reaching laterally to the outer and inner angles of
the orbit. The upper part of the sheath of the orbito-palpebralis muscle reaches
to the middle of the palpebral fascia, and is mainly continued forward between the
muscle and the fascia to the anterior surface of the tarsus.
896
ORGANS OF SPECIAL SENSE
The lower membrane (suspensory ligament of the eyeball), joined by the sheath
of the inferior rectus, reaches forward to the attached (hinder) border of the tarsus
of the lower lid, where it is mainly attached, while a part of it extends to the lower
palpebral fascia.
To understand the special bands mentioned above, we must follow the sheath
of each rectus muscle forwards, when we find that, while it is rather loosely applied
to the muscular belly in its posterior two-thirds, it then suddenly becomes thicker,
and is firmly attached to the muscle for some distance before finally leaving it, and
is thereafter often accompanied by some muscle-fibres. The best developed of
these bands, the external check ligament, passes forwards and outwards to the
outer angle of the orbit, helping to support the lachrymal gland on its way, and is
FIG. 486.-HORIZONTAL SECTION THROUGH LEFT ORBIT, VIEWED FROM ABOVE.
(After Von Gerlach. To show check ligaments, etc.)

TARSUS-
CONJUNCTIVAL FORNIX-
LACHRYMAL GLAND-
Outer palpebral-
ligament
External check-
ligament
OUTER ORBITAL WALL
External rectus-
Orbital fat-
EYEBALL
ORBICULARIS
PALPEBRARUM
SPACE OCCUPIED BY
SUBCONJUNCTIVAL
TISSUE, AND BY
TENON'S CAPSULE
FURTHER BACK
Upper part of
Horner's muscle
Palpebral fascia
Internal check
ligament
TENON'S SPACE
INNER WALL OF ORBIT
OPTIC NERVE
Internal rectus
ETHMOIDAL CELLS

inserted near the orbital edge immediately behind the external palpebral ligament.
The inner band, or internal check ligament, is larger than the outer, but not so
thick; it passes forwards and inwards to be inserted into the upper part of the
lachrymal crest and just behind it. These two bands, external and internal, come
from the sheaths of the corresponding recti muscles. From the sheath of the
superior rectus come two thin bands, one from each border. The inner joins the
sheath of the tendon of the superior oblique; the outer goes to the external angle of
the orbit, assisting in the support of part of the lachrymal gland. The sheath of the
inferior rectus is thickened in front, and, on leaving the muscle, goes to the middle
of the inferior oblique, splitting to enclose it; it then passes to be inserted into the
lower inner angle of the orbit close behind its margin, about midway between the
internal check ligament and the orbital attachment of the inferior oblique.
OPTIC NERVE
897
3. In addition to its partial investment by the muscle-fascia, the eyeball has a
special membrane enclosing its hinder two-thirds, usually called Tenon's capsule.
This is a thin, transparent tissue, situated immediately beneath the muscle-fascia.
It follows the curve of the sclerotic from the insertion of the recti to about 3 mm.
from the optic nerve entrance, when it leaves the eyeball and blends with the
posterior lamina of the muscle-fascia; the combined membrane may be traced
backwards, enveloping the optic-nerve sheath loosely, approaching it as it nears the
optic foramen, but never actually joining it. The interval between it and the nerve-
sheath is called the supravaginal lymph space. Tenon's capsule first comes into
relation with the muscles at the point where they are left by their proper sheaths;
it there invests their tendons, forms a small serous bursa on the anterior surface of
each, and adheres to the sclerotic in the form of a line running round the globe,
joining the insertions of the four recti muscles. Between this line and the corneal
border, the conjunctiva is separated from the sclerotic by the subconjunctival tissue,
strengthened by a fine expansion of the muscle-fascia.
The inner surface of the capsule is smooth, and is only connected with the
sclerotic by a loose, wide-meshed areolar tissue. This interval between the sclerotic
and capsule, known as Tenon's space, is a lymph cavity, and permits free move-
ments of the eyeball within the capsule.
Relation of Tenon's Capsule to the Oblique Muscles.-The capsule surrounds
the posterior third of the inferior oblique and its tendon, running along its ocular
surface till it meets the fascial band coming from the inferior rectus (see above),
and forming a serous bursa on the superficial surface of the oblique near its
insertion. The tendon of the superior oblique for about its last five millimetres
is invested solely by Tenon's capsule; in front of this, as far as the trochlea, the
tendon lies in a membranous tube derived from the muscle-fascia, the inner lining
of which is smooth, and may be considered as a prolongation of Tenon's capsule.

THE OPTIC NERVE
The part of this nerve with which we have here to do lies within the orbit,
extending from the optic foramen to the eyeball. Its course is somewhat S-shaped;
thus, on entering the orbit, it describes a curve, with its convexity down and out,
and then a second slighter curve, convex inwards. Finally, it runs straight
forwards to the globe, which it enters to the inner side of its posterior pole.
Besides curving as just described, the nerve also rotates on its long axis, so that
the surface which is below at the foramen becomes temporal before entering the
eyeball.
In its passage through the optic canal the nerve is surrounded by a pro-
longation of the meninges. The dura mater splits at the optic foramen, part
of it joining the periorbita, while the remainder continues to surround the
nerve loosely as its outer or dural sheath. The nerve is closely enveloped by
a vascular covering derived from the pia mater, named accordingly the pial
sheath. The space between these two sheaths, known as the intervaginal space,
is subdivided by a fine prolongation of the arachnoid (the arachnoidal sheath) into
two parts, viz. an outer, narrow, subdural, and an inner, wider, subarachnoid
space, communicating with the corresponding intracranial spaces. The arachnoidal
sheath is connected with the sheath on each side of it by numerous fine processes
which bridge across the intervening spaces. The pial sheath sends processes
inwards, which form a framework separating the bundles of nerve-fibres; between
the enclosed nerve-fibres and each mesh of this framework there is a narrow interval
occupied by lymph. The nerve-fibres are medullated, but have no primitive sheath.
About fifteen or twenty millimetres behind the globe the central vessels enter,
piercing obliquely the lower outer quadrant of the nerve, and then run forward

3 M
898
ORGANS OF SPECIAL SENSE
in its axis. They are accompanied throughout by a special process of the pial
sheath, which forms a fibrous cord in the centre of the nerve.
On reaching the eyeball, the dural sheath is joined by the arachnoid, and turns
away from the nerve to be continued into the outer two-thirds of the sclerotic.
Similarly the pial sheath also here leaves the nerve, its greater part running into
the inner third of the sclerotic, while a few of its fibres join the choroid; the inter-
FIG. 487.-TRANSVERSE SECTION THROUGH OPTIC NERVE, SHOWING THE RELATIONS OF
ITS SHEATHS AND CONNECTIVE-TISSUE FRAMEWORK.

SUBARACHNOID SPACE
SUBDURAL SPACE
OD
DURAL SHEATH
ARACHNOIDAL SHEATH
Central retinal artery
Central retinal vein
PIAL SHEATH
Connective tissue frame-
work, with meshes in
which the nerve-fibre
bundles lie
FIG. 488.-LONGITUDINAL SECTION THROUGH TERMINATION OF OPTIC NERVE.

CHOROID
Short posterior
ciliary artery
PHYSIOLOGICAL PIT
RETINA
PIGMENT EPITHELIUM
SUPRACHOROIDAL
SPACE
LAMINA CRIBROSA
SCLEROTIC
Central retinal
vessels
DURAL SHEATH
PIAL SHEATH
ARACHNOIDAL SHEATH-
OPTIC NERVE
WITH ITS
CONNECTIVE
TISSUE
FRAMEWORK
vaginal space consequently ends abruptly in the sclerotic around the nerve-entrance.
In this locality the connective-tissue framework of the nerve becomes thicker and
closer in its meshwork, and has been already alluded to as the lamina cribrosa. It
is formed by processes passing out from the central fibrous cord at its termination,
and by processes passing inwards from the pial sheath, sclerotic, and choroid. It does
not pass straight across the nerve, but follows the curve of the surrounding sclerotic,
being therefore slightly convex backwards. The nerve-trunk here quickly becomes

OPTIC NERVE 30
899
reduced to one-half its former diameter, the fibres losing their medullary sheath,
and being continued henceforward as mere axis cylinders. Apart from the conse-
quent loss of bulk, this histological change may be readily recognised macroscopi-
cally in a longitudinal section of the nerve, its aspect here changing from opaque
white to semi-translucent grey. The part of the nerve within the lamina cribrosa
has already been seen in our ophthalmoscopic examination of the living eye.
The optic nerve is mainly nourished by fine vessels derived from those of the
pial sheath, which run into the substance of the nerve in the processes above
mentioned. In front of the entrance of the central retinal artery this vessel aids
to some extent in the blood-supply of the axial part of the nerve.
FIG. 489.-THE BLOOD-VESSELS OF THE LEFT ORBIT, VIEWED FROM ABOVE.
Supraorbital artery
LACHRYMAL GLAND
Superior rectus.
EYEBALL
External rectus.
Commencement of superior
ophthalmic vein
Reflected tendon of
superior oblique
Ophthalmic artery
Anterior ethmoidal artery
Lachrymal artery.
Superior rectus, cut.
Inferior ophthalmic vein
Superior ophthalmic vein.
OPTIC NERVE-
Posterior ethmoidal artery
Ciliary arteries
Levator palpebræ, cut
Ligament of Zinn
Ophthalmic artery
Common ophthalmic vein.
OPTIC COMMISSURE
Internal carotid artery
THE BLOOD-VESSELS AND NERVES OF THE ORBIT
As these structures will be more particularly described in other sections of this
work, a very short general account will suffice here.
Arteries. The main blood-supply is afforded by the ophthalmic artery, a branch
of the internal carotid, which gains the orbit through the optic canal, where it lies.
beneath and to the temporal side of the nerve. On entering the orbit it ascends, and
passes obliquely over the optic nerve to the inner wall of the orbit; in this early
part of its course it gives off most of its branches, which vary much in their
manner of origin and also in their course. The arteries of the orbit are remarkable
for their tortuous course, for their delicate walls, and for their loose attachment to the
surrounding tissues. The ophthalmic artery gives off special branches in the orbit
to the lachrymal gland, the muscles, the retina (through the optic nerve), and the
eyeball, as well as to the meninges, the ethmoidal cells, and the nasal mucous
membrane. Twigs from all the different branches go to supply the fat, fasciæ, and
ordinary nerves of the orbit. Branches which leave the orbit anteriorly ramify on
the forehead and nose, and also go to the supply of the eyelids and the tear-passages.
3 M 2

900
ORGANS OF SPECIAL SENSE
The ophthalmic artery has many anastomoses with branches of the external carotid.
The contents of the orbit are also supplied in part by the infraorbital artery, a branch
of the internal maxillary; in particular this artery supplies part of the inferior
rectus and inferior oblique muscles in the cavity, and also gives a branch to the
lower eyelid.
Veins.-Branches, corresponding generally to those of the artery, unite to form
the superior and inferior ophthalmic veins, which ultimately, either separately or
united into one trunk, pass through the sphenoidal fissure and empty into the
cavernous sinus. The inferior vein is connected with the pterygoid plexus by a
branch which leaves the orbit by the spheno-maxillary fissure.
Nerves of the orbit. These are motor, sensory, and sympathetic, and all enter
the orbit by the sphenoidal fissure, with the exception of one small sensory branch
passing through the spheno-maxillary fissure. (The optic nerve has been already
described, and is not included in this account.)
A. The motor nerves are the third, fourth, and sixth cranial.
FIG. 490.-SECTION THROUGH CONTENTS OF RIGHT ORBIT, 1-2 MM. IN FRONT OF
THE OPTIC FORAMEN, VIEWED FROM BEHIND.
FOURTH NERVE
Superior rectus and levator
palpebræ superioris muscles
Superior oblique muscle
OPTIC NERVE
Internal rectus muscle
Inferior rectus muscle
(After Lange.)
Ophthalmic vein
OPHTHALMIC NERVE
(FRONTAL, NASAL,
AND LACHRYMAL
BRANCHES)
-Ophthalmic vein
Ophthalmic artery
SIXTH NERVE
THIRD NERVE
External rectus muscle
1. The third nerve enters the orbit in two parts, an upper smaller, and a lower
larger division. The upper division gives off two branches: one supplies the superior
rectus, entering its lower surface far back; the other branch goes to the levator
palpebræ, entering its lower surface in its posterior third. The lower division
divides into three branches, of which one supplies the inferior rectus, entering its
upper surface far back, and another supplies the internal rectus, entering its inner
surface a little behind its middle. The third branch of the lower division gives
(1) the short root to the ciliary ganglion, and (2) one or more twigs to the inferior
rectus, and the remainder of this branch then enters the lower surface of the
inferior oblique muscle about its middle.
2. The fourth nerve supplies the superior oblique muscle, entering its upper
surface about midway in its course.
3. The sixth nerve supplies the external rectus, entering its inner surface about
the junction of the posterior and middle thirds of the muscle.
As regards the manner of termination of these motor nerves, it is found that
in all the ocular muscles the nerve on its entrance breaks up into numerous
bundles of fibres, which form first coarse and then fine plexuses, the latter ulti-
mately sending off fine twigs supplying the muscle throughout with nerve-endings.
The posterior third of these muscles is, however, comparatively ill supplied with
both kinds of plexus and with nerve-endings.
NERVES OF ORBIT
901
B. The sensory nerves are supplied by the first and second divisions of the fifth
cranial nerve. The first division, or ophthalmic nerve, is entirely orbital; while
the second, or maxillary, only sends a small branch to the orbit.
1. The ophthalmic division of the fifth nerve enters the orbit in three divisions,
namely:-
(1) Frontal, splitting subsequently into supratrochlear and supraorbital, both
passing out of the orbit. It is distributed to the corresponding upper eyelid, and the
skin over the root of the nose, the forehead, and the hairy scalp as far back as the
coronal suture on the same side. It also gives branches to the periosteum in this
region, and to the frontal sinus.
(2) Lachrymal, supplying the lachrymal gland, anastomosing with a branch of
the superior maxillary in the orbit, and finally piercing the upper eyelid. Outside
the orbit it is distributed to the outer part of the upper lid, the conjunctiva at the
external canthus, and the skin between this and the temporal region.
(3) Nasal, giving off (a) a branch to the ciliary ganglion, constituting its long
root; (b) two or three long ciliary nerves; and (c) the infratrochlear, passing out
of the orbit. The nasal nerve then leaves the orbit, re-entering the cranial cavity
before being finally distributed to the nose. The infratrochlear branch supplies the
eyelids and skin of the side of the nose near the inner canthus, the lachrymal sac,
caruncle, and plica semilunaris. The nasal nerve, after its second course in the
cranial cavity, passes through an aperture in the front of the cribriform plate of the
ethmoid bone, and is ultimately distributed to the nasal mucous membrane, and to
the skin of the side and ridge of the nose near its tip.
2. The maxillary division of the fifth nerve gives a branch, called the orbital
nerve, which passes into the orbit through the spheno-maxillary fissure, anastomoses
with the lachrymal, and leaves the orbit in two divisions. These are distributed to
the skin of the temple and of the prominent part of the cheek.
A few minute twigs from Meckel's ganglion, and sometimes from the maxillary
division of the fifth nerve, also pass through the spheno-maxillary fissure to
supply the periorbita in this neighbourhood.
C. The sympathetic nerves of the orbit are derived from the plexus on the
internal carotid. With the exception of branches accompanying the ophthalmic
artery, and of the distinct sympathetic root of the ciliary ganglion, they enter the
orbit in the substance of the other nerve-cords. The connections between the ocular
nerves and the carotid plexus are recognisable as fibres going to the third, sixth,
and ophthalmic nerves; as a rule, the comparatively large twigs going to the sixth
join it furthest back, and those to the third furthest forward. Sympathetic
connections with the fourth nerve are very doubtful.
The lenticular or ciliary ganglion is situated between the optic nerve and
external rectus far back in the orbit. Its three roots-motor, sensory, and sympa-
thetic-have been already mentioned. Anteriorly, it gives off three to six small
trunks, which subdivide to form the short ciliary nerves, about twenty in number,
piercing the sclerotic around the optic nerve entrance.
The lymphatic system of the orbit. Although there are no lymphatic vessels
or glands in the orbit, the passage of lymph is nevertheless well provided for. We
have already observed the lymph channels within, between, and outside the sheaths
of the optic nerve, and have seen how these communicate anteriorly with the
lymph channels of the eyeball, and posteriorly with the intracranial meningeal
spaces. In addition, there are lymph-spaces around the blood-vessels, situated
between the outer coat and the loose investment furnished by the muscle-fascia.
The nerves of the orbit (apart from the optic) are probably similarly surrounded
by lymph-spaces. In the absence of lymphatic vessels it is difficult to trace the
circulation thoroughly; much of the lymph from the orbital cavity is said to pass
into the internal maxillary glands.



902
ORGANS OF SPECIAL SENSE
THE EYELIDS
The cutaneous and conjunctival surfaces of the lids have already been
examined, and the position of the tarsus has been indicated. We have now to
ascertain the nature and relations of the tarsus, and describe the other tissues
entering into the formation of the eyelids.
The skin here is thin, bearing fine hairs, and having small sebaceous and
numerous small sweat glands. Immediately beneath it is a loose subcutaneous
tissue, destitute of fat, separating the skin from the palpebral part of the orbicularis
FIG. 491.-VERTICAL TRANSVERSE SECTION THROUGH THE UPPER EYELID.
Cutaneous surface just
above superior palpe-
bral fold
Orbicularis fibres, cut
across
SWEAT GLAND
FINE HAIR WITH SEBACEOUS
GLAND AT ITS BASE
ad
Orbicularis fibres, cut.
Sizia
across
Midgo
MODIFIED SWEAT GLAND OF
MOLL
CILIUM
(After Waldeyer and Fuchs.)

CONJUNCTIVA NEAR FORNIX
Anterior layer of inser-
tion of levator pal-
pebræ superioris
Superior palpebral
muscle of Müller
Fibres from levator
passing through
orbicularis to skin
Superior vascular arch,
cut across
WALDEYER'S GLANDS
Conjunctival papillæ
over attached border
of tarsus
Musculus ciliaris
Riolani
Posterior edge of lid-
margin
OPENING OF DUCT OF
MEIBOMIAN GLAND
muscle. The lid-fibres of this muscle arise from the inner palpebral ligament, and
course over the whole upper and lower eyelids in a succession of arches, so as to
meet again beyond the outer canthus; there they in part join one another, in part
are inserted into the outer palpebral ligament. The muscular fibres are arranged
in loose bundles, with spaces between them occupied by connective tissue; in the
upper lid these connective tissue fibres may be traced upwards and backwards into
the fibrous expansion of the tendon of the levator palpebræ superioris. One strong
bundle of orbicularis fibres, called the musculus ciliaris Riolani, is found near the
edge of the lid, in front of, and behind, the efferent ducts of the Meibomian glands.

THE EYELIDS
903
✓
A central connective tissue separates the orbicularis muscle from the tarsus in
the tarsal division of the lids. In the upper lid this is to be regarded as mainly
the anterior or fibrous expansion of the tendon of the levator palpebræ, which
sends connective tissue septa between the bundles of the overlying orbicularis (as
just mentioned) going to the skin. In the orbital part of this lid the central con-
nective tissue includes also the palpebral fascia, lying here immediately beneath the
orbicularis muscle; but this soon thins off and fades into the more deeply placed
levator expansion. This latter is strengthened by an extension of the sheath of
the superior rectus, by which this muscle is enabled to influence the elevation of
the lid indirectly. In the lower lid the central connective tissue similarly consists
of palpebral fascia, blended with a thin fibrous extension of the sheath of the
inferior rectus. Immediately in front of each tarsus is a little loose connective
tissue, which contains the large blood-vessels and nerves of the lids.
The tarsus of each lid is a stiff plate of close connective tissue, with its sur-
faces directed anteriorly and posteriorly; in its substance the Meibomian glands
are embedded. One tarsal border is free, viz. towards the edge of the lid, the
other is attached; the former is straight, while the latter is convex, especially in
the upper lid. The length of each tarsus is about twenty millimetres. Its breadth
is greatest in the middle of the lid, and becomes gradually smaller towards each
canthus, where the tarsi are joined to the outer and inner palpebral ligaments. The
breadth of the upper tarsus (10 mm.) is about twice that of the lower. The thickness
of each is greatest, and its texture closest, at the middle of its length, thinning off
towards the canthi and towards both borders. Into the superior anterior border of
the upper tarsus the lower layer of the levator expansion is attached, consisting
of smooth muscle-fibres constituting the superior palpebral muscle of Müller.
In like manner, at the inferior border of the lower tarsus, bundles of smooth
muscle fibre are inserted (the inferior palpebral muscle of Müller), developed in
what has been regarded as part of the extension of the sheath of the inferior
rectus.
The palpebral conjunctiva is firmly adherent to the back of the tarsus; but in
the orbital part of the lid loose subconjunctival tissue intervenes between it and
Müller's palpebral muscle. Adenoid tissue occurs in the substance of the conjunc-
tiva, especially in its orbital division. Near the upper fornix, the conjunctiva
receives expansions of the tendon of the levator palpebræ and of the sheath of the
superior rectus, and, at the lower fornix, of the sheath of the inferior rectus. The
surface of the tarsal conjunctiva shows small elevations or papillæ everywhere;
but these are particularly well marked over the attached border of the tarsus.
Glands of the eyelids. From its manner of formation the eyelid may be
regarded as consisting of two thicknesses of skin, the inner (or posterior) having
been doubled back upon the outer at the edge of the lid; thus the cuticle and
corium of the skin proper are represented respectively by the conjunctiva and tarsus
of the inner thickness. At the free border of the lid, accordingly, we find glands
corresponding to the sebaceous and sweat glands of the skin, viz. large sebaceous
glands of the cilia (Zeiss's glands) and Moll's modified sweat glands. Again, in the
inner skin-thickness of the lid, the Meibomian glands of the tarsus are sebaceous,
and acino-tubular glands present at the attached border of the tarsus (Waldeyer's
glands) may be reckoned as modified sweat glands. Glands similar in structure to
Waldeyer's also occur at the fornix, and are especially abundant near the outer
canthus of the upper lid, close to the efferent ducts of the lachrymal gland; from
their structure, and the character of their secretion, these acinous or acino-tubular
glands have been termed by Henle accessory lachrymal glands.' Other simple
tubular glands (Henle), formed merely by the depressions between the papillæ,
are best developed in the inner and outer fourths of the tarsal conjunctiva of
both lids.

6

904
ORGANS OF SPECIAL SENSE
Blood-vessels.-The arteries run in the central connective tissue of the lids,
mainly in the form of arches near the borders of the tarsus, from which twigs go
to the different palpebral tissues. They are supplied by the lachrymal and palpebral
branches of the ophthalmic, and by small branches derived from the temporal
artery. The veins are more numerous and larger than the arteries, and form a
close plexus beneath each fornix. They empty themselves into the veins of the
face at the inner, and into the orbital veins at the outer canthus.
The lymphatic vessels of the lids are numerous, and are principally situated in
the conjunctiva. Lymph-spaces also surround the follicles of the Meibomian
glands. The palpebral lymphatic vessels mainly pass through the preauricular
gland; but, sometimes at least, those from the inner half of the lower lid go to the
submaxillary lymphatic glands.
Nerves. (a) Sensory. The upper lid is chiefly supplied by branches of the
supraorbital and supratrochlear nerves, the lower lid by one or two branches of
the infraorbital. At the inner canthus the infratrochlear nerve also aids in the
supply, and, at the outer canthus, the lachrymal. (b) Motor. The palpebral part
of the orbicularis is supplied by branches of the facial nerve, which mainly enter
it near the outer canthus. Müller's palpebral muscles are supplied by the sympa-
thetic nervous system.
The inner palpebral ligament, or tendo oculi, has been referred to previously.
Arising from the frontal process of the maxilla, it extends outwards over the
front wall of the lachrymal sac, bends round the outer wall of the sac, and then
passes backwards to the posterior crest on the lachrymal bone. It is thus U-shaped,
having its limbs anterior and posterior, embracing the lachrymal sac; the anterior
limb lies immediately beneath the skin, and is visible in the living. The palpebral
fibres of the orbicularis are inserted into the outer surface of both limbs, those
attached to the posterior limb constituting Horner's muscle. The outer palpebral
ligament is merely a stronger development of connective tissue in the orbicularis.
Both ligaments are connected with the tarsi as already mentioned.

THE LACHRYMAL APPARATUS
The tears are secreted by an acinous gland, and flow through fine ducts to the
upper outer part of the conjunctival sac, whence they are drained off through the
puncta, pass along the canaliculi into the lachrymal sac, and ultimately run down
the nasal duct to gain the inferior meatus of the nose.
The lachrymal gland is situated near the front of the outer part of the roof of
the orbit, lying in a depression in the orbital plate of the frontal bone. It consists
of two very unequal parts, one placed above and the other beneath the tendinous
expansion of the levator palpebræ superioris, but small gaps in the expansion
permit of connections between these two parts of the gland. The upper and larger
subdivision (superior lachrymal gland) is a firm elongated body, about the size of
a small almond; it has a greyish-red colour, and is made up of closely aggregated
lobules. The upper surface (next the orbital roof) is convex, and its lower surface
is slightly concave. Anteriorly, the gland almost reaches the upper orbital
margin, and it extends backwards for approximately one-fourth the depth of the
orbit, measuring about twelve millimetres in this direction. The outer border of
the gland descends to near the insertion of the fascial expansion of the external
rectus, while its inner border almost reaches the outer edge of the superior rectus;
its transverse measurement is about twenty millimetres. It is enveloped in a
capsule, which is slung by strong fibrous bands passing to its inner border from
the orbital margin (suspensory ligament of the gland).
The lower subdivision of the gland (inferior lachrymal gland) is composed of
LACHRYMAL APPARATUS
905
loosely applied lobules, and lies immediately over the outer third of the upper
conjunctival fornix, reaching outwards as far as the external canthus.
Each subdivision of the gland possesses several excretory ducts, which all open on
the outer part of the upper fornix conjunctivæ, about four millimetres above the
upper border of the tarsus. Those of the superior gland, three or four in number,
pass between the lobules of the lower gland; the outermost duct is the largest, and
opens at the level of the external canthus. The ducts of the inferior gland in part
discharge themselves into those of the upper, but there are also several fine ducts
from this subdivision that run an independent course.
Near the inner canthus are the two puncta lachrymalia, upper and lower, each
situated at the summit of its papilla. The top of each papilla curves backwards
towards the conjunctival sac, so that the puncta are well adapted for their function
of draining off any fluid collecting there.
The canaliculi lachrymales extend from the puncta to the lachrymal sac. The
lumen at the punctum is horizontally oval, from its lips being slightly compressed
antero-posteriorly; the lumen of the lower punctum is somewhat larger than that
of the upper. As the lower papilla is a little further from the inner canthus than
the upper, the corresponding canaliculus is longer.
FIG. 492.-LACHRYMAL APPARATUS. (After Schwalbe.)

SUPERIOR LACHRYMAL GLAND
INFERIOR LACHRYMAL GLAND
DUCT FROM SUPERIOR GLAND
UPPER EYELID PARTIALLY
DIVESTED OF SKIN
UPPER PUNCTUM
LACHRYMAL SAC, NEAR ITS FUNDUS
COMMON DUCT FORMED BY
JUNCTION OF CANALICULI
UPPER AND LOWER CANALICULI
LOWER PUNCTUM
NASAL DUCT
On tracing either canaliculus from its origin, we find that at first it runs
nearly vertically for a short distance, then bends sharply towards the nose, and
finally courses more or less horizontally, converging slightly towards its fellow,
and not infrequently joining it before opening into the sac. The calibre varies
considerably in this course, being narrowest a short distance from the punctum,
and widest at the bend, from which point it again narrows very gradually as it
nears the sac. The wall of the canaliculus consists mainly of elastic and white
fibrous tissue, lined internally by epithelium, and covered externally by striated
muscle (part of the orbicularis). The muscle-fibres run parallel to the canaliculus
in the horizontal part of its course; but they are placed, some in front and some
behind, around the vertical part, acting here as a kind of sphincter. Just before
their termination, the canaliculi pierce the periosteal thickening that constitutes
the posterior limb of the inner palpebral ligament.
The lachrymal sac lies in a depression in the bone at the inner angle of the
orbit (the lachrymal fossa). It is vertically elongated, and narrows at its upper and
lower ends; the upper extremity or fundus is closed, while the lower is continuous
directly with the nasal duct. Laterally, the sac is somewhat compressed, so that
its antero-posterior is greater than its transverse diameter. The canaliculi, either
separately or by a short common tube, open into a bulging on the outer surface

906
ORGANS OF SPECIAL SENSE
of the sac near the fundus. As has previously been mentioned, the sac is
surrounded by periosteum, but between this and the mucous membrane forming
the true sac-wall there is a loose connective tissue, so that the cavity is capable
of considerable distension. The relations of the inner palpebral ligament have
already been described; it is to be noted that the fundus of the sac extends above
this ligament.
The nasal duct reaches from the lower end of the sac to the top of the inferior
meatus of the nose, opening into the latter just beneath the adherent border of the
inferior turbinated bone. Traced from above, its main direction is downwards,
but it has also a slight inclination backwards and outwards. It lies in a bony
canal, whose periosteum forms its outer covering. Between this and the mucous
membrane of the duct there is a little intermediate tissue, in which run veins of
considerable size connected with the plexus of the inferior turbinated bone. The
duct does not usually open directly into the nasal cavity at the lower end of the
bony canal, but pierces the nasal mucous membrane very obliquely, so that a flap
of mucous membrane covers the lower border of the opening in the bone, upon
which flap the tears first trickle after escaping from the duct proper.
The sac and nasal duct together constitute the lachrymal canal, lined through-
out by a continuous mucous membrane. This membrane presents folds in some
situations, especially near the opening of the canaliculi, at the junction of the sac
and duct and at the lower end of the duct. That at the top of the duct is the most
important, as it sometimes interferes with the proper flow of tears out of the sac.
The total length of the lachrymal canal is roughly twenty-four millimetres, half of
this being sac, and half nasal duct. If, however, we reckon as duct the oblique
passage through the nasal mucous membrane, this measurement may occasionally
be increased by eight or ten millimetres. The lachrymal sac, when distended,
measures about six millimetres from before backwards, by four millimetres trans-
versely. The nasal duct is practically circular, and has a diameter of about three
millimetres, rather less at its junction with the sac, where we find the narrowest
part of the whole lachrymal canal.
THE EAR
BY ARTHUR HENSMAN, F.R.C.S.
LECTURER ON ANATOMY AT THE MIDDLESEX HOSPITAL MEDICAL COLLEGE; AND SURGEON TO THE THROAT
AND EAR DEPARTMENT OF THE MIDDLESEX HOSPITAL.
The organ of hearing may be divided into three parts:-the EXTERNAL EAR,
which includes the pinna and external auditory meatus; the MIDDLE EAR, or
tympanum, with its ventilating shaft the Eustachian tube; and the INTERNAL EAR,
which includes the osseous labyrinth, within which is placed-the essential portion
of the organ-the membranous labyrinth.
THE EXTERNAL EAR
The Pinna, or Auricle, is attached to the side of the head, midway between the
forehead and occiput. Its level is indicated by horizontal lines extending backwards
from the eyebrows above, and from the tip of the nose below. Somewhat pyriform in
shape, its irregular concave outer surface is turned more or less forwards, but the
FIG. 493.-EXTERNAL VIEW OF THE LEFT AURICLE.

Triangular fossa-
TRAGUS
ANTITRAGUS.
LOBULE
-Scaphoid fossa
-HELIX
-ANTIHELIX
а
angle of inclination varies considerably in different subjects. The incurved rim of
the ear, which divides its surfaces, commences below in a deep concavity which
surrounds, like the mouth of a trumpet, the external auditory meatus. This rim
is called the helix, and, traced round the ear, ends below at the posterior margin of
the lobule. On the upper part of the inverted edge of the helix a little irregular
process often exists, which has been regarded as the shrivelled tip of the primitive
908
ORGANS OF SPECIAL SENSE
ear. The hollow from which it starts is called the concha. Within the helix, but
separated by the scaphoid fossa (fossa of the helix) runs a second curved ridge, the
antihelix. It commences below in the little process known as the antitragus, and
bifurcating superiorly, bounds a shallow fossa just above the concha, the so-called
triangular fossa (fossa of the antihelix). The concha bounded by the helix is
deeply notched below (incisura intertragica). Overlapping the commencement of
the notch before and behind are two eminences, the anterior and larger, the tragus;
the posterior, the antitragus. The auricle varies greatly in different individuals,
and the lobe perhaps more than any other part.
The cartilaginous framework of the ear, although it does not enter into all
its parts, gives to it the general character and appearance already described.
It consists of pliable reticular cartilage of the yellow elastic kind. It does not
enter into the formation of the lobule, which consists entirely of dense connec-
tive tissue and fat. Its lower portion is so rolled upon itself as to form a tube
incomplete above, which tails off as it passes inwards to be attached to the lower
third of the external auditory meatus. This attachment is effected by means
of a dense fibro-elastic tissue which allows considerable shifting on traction of
the pinna upwards and backwards. A section passing through the orifice of the
meatus shows the cartilage greatly in excess of the fibrous membrane which
FIG. 494.-SECTION THROUGH THE ORIFICE OF THE RIGHT EXTERNAL AUDITORY MEATUS.

Fissure of Santorini.
Posterior auricular artery-
Section of cartilaginous portion.
EXTERNAL AUDITORY CANAL
Lining membrane
Fissure of Santorini
completes its contour. Deeper sections show the cartilage diminishing more
and more until it forms scarcely a third of the lumen of the tube near the bony
meatus.
The channel is traversed by a couple of fissures, the fissures of Santorini; but
these are not constant in their number, extent, or direction. These intervals are
filled with fibrous tissue, and allow the canal to be straightened by traction on the
pinna. The lower segment of the cartilaginous meatus is in close contact with
the parotid gland. An abscess in this region may thus burrow through the fissures
and discharge itself through the external meatus. There is also a gap between
the helix and the tragus bridged over by a band of dense fibrous tissue. Several
fissures traverse the cartilage, and a deep cleft dividing the antihelix severs the
caudate process from the rest of the cartilage below.
Ligaments. An anterior ligament connects the helix with the root of the
zygoma, and a posterior passes from the concha to the mastoid process.
A pair of ligaments belong to the cartilage itself, the strong band already
described completing the orifice of the meatus, and one less marked passing between
the concha and the processus caudatus.
Muscles. The extrinsic muscles, the attollens, attrahens, and retrahens aurem,
have been described on page 458. The special intrinsic muscles are six in number.
They are difficult to display, and sometimes appear to be absent.

EXTERNAL EAR
909
Helicis major is a narrow slip which arises from a small tubercle, and passes
upwards along the rim of the helix to near its summit.
Helicis minor is an oblique fasciculus overlying the commencement of the helix.
The tragicus consists of nearly vertical fibres lying over the outer surface of
the tragus.
The antitragicus arises from the outer surface of the antitragus to pass to the
caudate process.
The transversus auris consists of mixed muscular and tendinous fibres which
with the following lies on the cranial aspect of the pinna, and traverses the hollow
formed between the bulging of the concha and the convexity corresponding to the
groove of the helix.
The obliquus auris crosses the hollow between the concha and fossa of the
antihelix.
FIG. 495.-EXTERNAL AND INTERNAL SURFACE OF THE CARTILAGE OF THE
RIGHT PINNA AND ITS MUSCLES, ETC.

HELIX
Helicis minor
Fibrous band
completing fore
part of meatus
PROCESSUS
CAUDATUS
Anti-tragicus
Helicis major
Obliquus
Tragicus
Fissure of Santorini
Transversus
Vessels. The arteries are the posterior auricular from the external carotid,
and the anterior auricular from the temporal.
The veins enter the posterior auricular and temporal.
Nerves. The great auricular supplies the cranial aspect, sending a few
filaments to the outer surface near the lobule.
The posterior auricular of the facial and the auricular branch of the pneumo-
gastric also supply the cranial aspect.
The auriculo-temporal supplies the outer aspect of the pinna. The tip of the
ear at the inner part receives the auricular branch of the small occipital. This is
sometimes replaced by a branch from the great occipital.
The intrinsic muscles receive their supply from the temporal and posterior
auricular branches of the facial.
The External Auditory Meatus is about an inch and a quarter in length (3 cm.).
It commences at the bottom of the concha, and passes inwards and a little forwards
to end at the membrana tympani. It is narrower at its centre. Near its orifice it
is oval from above downwards, but at its termination it is somewhat broader from
side to side. Owing to the obliquity of the membrana tympani, the floor is longer
than the roof, and the anterior longer than the posterior wall of the canal.
910
ORGANS OF SPECIAL SENSE
Its cartilaginous portion, which is about half an inch (1.3 cm.) in length,
is formed by the incomplete tube of cartilage already described, with fibrous
membrane to complete its upper and back part.
The osseous portion of the tube is about three-quarters of an inch (14-16 mm.)
in length, and is slightly curved, with its convexity looking upwards and backwards
(page 45).
The lining membrane is a reflexion from the skin externally. It is thick and
strong in the cartilaginous, but becomes thinner in the osseous portion; especially
is this the case near the membrana tympani, over which it is reflected to form its
cuticular layer. In the cartilaginous portion the dermis is supplied with numerous
hairs, and sebaceous glands open into their follicles. Tubular ceruminous glands,
the orifices of which stud the whole of the cartilaginous portion, appear as dark
points to the naked eye.
FIG. 496.-SECTION OF THE MIDDLE AND EXTERNAL EAR.

CAVITY OF
TYMPANUM
Membrana
COCHLEA tympani
SEMI- GLANDS
CIRCULAR IN OSSEOUS
CANALS MEATUS
CARTILAGE
PINNA
-CARTILAGINOUS MEATUS
OSSEOUS MEATUS
CARTILAGE OF EXTERNAL
MEATUS
PAROTID GLAND
STYLOID PROCESS
-Internal carotid
artery
CARTILAGINOUS EUSTACHIAN OSSEOUS EUSTACHIAN
TUBE
TUBE
These glands extend a short distance into the upper and back part of the bony
meatus, in the form of a triangular patch, but elsewhere they appear to be absent.
The arteries are derived from the posterior auricular, temporal, and internal
maxillary; and the nerves from the auriculo-temporal.
THE MIDDLE EAR
The Membrana Tympani is an irregularly rounded concave membrane stretched
obliquely across the bottom of the osseous meatus in such wise as to form an
obtuse angle with its upper wall (according to Von Tröltsch, 140°) and an acute one
with its lower.
MIDDLE EAR
911
The circumference of the membrane is lodged in the groove of the tympanic
ring. Above and in front where the ring is wanting there is a slight recess known
as the notch of Rivini, and here the membrane is extended outwards, to unite with
the grooveless margin of the tympanum to form what is known as the Rivinian
segment.
The shape of the membrane varies with that of the inner end of the meatus.
Its long axis is from above downwards and forwards. The membrane, broadly
viewed, is concave externally, and convex towards the cavity of the tympanum.
This is mainly due to the traction of the handle of the malleus, which descends
obliquely downwards and backwards between its two inner layers to a point a little
below the centre of the membrane. This curvature is deepest at the umbo, opposite
the flattened extremity of the handle. In front of and below the umbo, extending
towards the periphery, the membrane is slightly convex externally.
At the anterior superior pole, the short process of the malleus is plainly visible
as a rounded point projecting outwards. A fold of the membrane passes backwards,
and another forwards from this spot, and above these folds may, under favourable
FIG. 497.-EXTERNAL VIEW OF THE LEFT MEMBRANA TYMPANI. (Enlarged from life.)
Shrapnell's membrane

Anterior fold of membrana
tympani
SHORT PROCESS OF MALLEUS
UMBO, OR LOWER EXTREMITY OF
HANDLE OF MALLEUS
Cone of light
Posterior fold of membrana tympani
LONG PROCESS OF INCUS
Posterior portion of
membrana tympani
conditions, be seen two short, tightly stretched striæ, which, taking origin from the
corners of the notch of Rivini above, converge as they descend to meet at the
short process. The membrane between these striæ and the edge of the notch is
thin and flaccid, and appears above the short process as a small pit-like depression
(membrana Shrapnelli). An anastomosis between the tympanic vessels and those of
the external meatus occurs at this spot.
Viewed from within, the head of the malleus is seen above the membrane
articulating with the incus, its curved handle passing downwards and slightly back-
wards between its layers, and strongly projecting from the inner surface. The
chorda tympani nerve may be seen crossing the neck of the malleus forwards to
the Glaserian fissure. Folds of the membrane occur in front of and behind the
malleus, forming what are known as the anterior and posterior pouches of the
membrana tympani. The free margin of the posterior pouch is commonly well
marked. Passing slightly downwards and outwards to the base of the handle of
the malleus, is the strongly marked fold containing the tendon of the tensor
tympani muscle.
Structure. The membrana tympani consists of three layers-a special fibrous
layer, with a cuticular covering externally continuous with that which lines the

912
ORGANS OF SPECIAL SENSE
auditory meatus; and a mucous lining internally derived from the tympanic
cavity.
The fibrous layer consists of two lamellæ closely connected-an external, in
which the fibres radiate from the handle of the malleus; and an internal, the fibres
of which are arranged concentrically, and are especially strong at the circumference.
The membrane of Shrapnell is extremely thin, and consists only of the outer
and inner layers, the fibrous layer being absent.
The handle of the malleus descends between the two inner layers, accompanied
by the vessels, which are often clearly visible in the living membrane.
The Tympanic Cavity is irregular in shape, laterally compressed, and communi-
cates posteriorly with the mastoid antrum and cells. It contains air, which reaches
it through the Eustachian tube, and is crossed from without inwards by a chain of
movable bones-the tympanic ossicles-through which vibrations which reach the
membrana tympani are conducted to the internal ear.
FIG. 498.-INTERNAL VIEW OF RIGHT MEMBRANA TYMPANI. (Enlarged.)

Suspensory ligament of malleus INCUS
HEAD OF MALLEUS.
CHORDA TYMPANI-
NERVE
Tendon of tensor.
tympani
-Posterior ligament of
incus
POSTERIOR PORTION OF
RECESS FOR OSSICLES
ABOVE MEMBRANE
FOOTPIECE OF STAPES
HANDLE OF MALLEUS-
Tensor tympani muscle-
LENTICULAR PROCESS (OS
ORBICULARE)
-Posterior portion of
membrana tympani
EUSTACHIAN TUBE-
The roof, which is about three lines in breadth, is thin, and separates the cavity.
from the interior of the cranium.
The floor is much narrower, but is similarly separated from the jugular fossa.
The outer wall is chiefly formed by the membrana tympani, already described,
and the bony wall above and below it.
The chorda tympani nerve, which traverses the outer wall, enters by a minute
orifice, the aperture of the iter chorda posterius, and leaves the cavity by the iter
chordæ anterius, which leads into the canal of Huguier. The Glaserian fissure
lies immediately below the latter orifice, but these minute openings are hidden by
the mucous lining.
The inner wall is vertical, and looks directly outwards; it presents the fenestra
ovalis and fenestra rotunda with the intervening grooved promontory, which
corresponds to the first turn of the cochlea, and the ridge marking the course of
the Fallopian canal, which is traversed by the facial nerve.
THE EAR
913
The reniform orifice of the fenestra ovalis leads into the vestibule, and is occu-
pied by the base of the stapes with its annular ligament, in addition to the lining
membrane derived from the cavities with which it communicates.
The fenestra rotunda leads into the cochlea, and is closed by a membrane (the
secondary membrane of Scarpa), concave towards the tympanum. This consists
of three layers-a middle fibrous layer, covered by the mucous lining of the
tympanum externally, and by the serous layer of the cochlea internally.
The posterior wall presents the hollow pyramid which lodges the stapedius
muscle and the openings which lead into the mastoid antrum and cells; these vary
much in size, and receive a mucous lining from the cavity.
The anterior wall, which is separated by a thin layer of bone from the carotid
canal, presents the orifice of the small canal, filled in the recent state by the tensor
tympani muscle, the orifice of the Eustachian tube, and the intervening plate of
bone, the processus cochleariformis.
The EUSTACHIAN TUBE is nearly two inches (2.5 cm.) in length, and passes
from the tympanum downwards, forwards, and inwards. It is partly bony and
partly cartilaginous.
The osseous portion is about half an inch (1.3 cm.) in length. It commences
just below the orifice which transmits the tendon of the tensor tympani muscle, and,
gradually contracting, ends by a jagged and oblique orifice between the petrous and
squamous portions of the temporal bone. To this is attached the cartilaginous
portion of the tube, which is about an inch in length. This is composed of an elon-
gated triangular plate, so folded upon itself as to leave an interval below which is
completed by fibrous tissue. At first narrow, the canal becomes much expanded
towards its trumpet-shaped termination. Its orifice, which is somewhat oval, opens
into the upper part and side of the pharynx, on a level with the inferior meatus.
The mucous membrane possesses a ciliated lining. It is thin near the tympanic
cavity, but it is much more vascular, thicker, and possesses mucous glands and
adenoid tissue near its pharyngeal orifice.
Sections of the cartilaginous portion of the tube show that the cartilaginous
plate is curled round like a hook above, and that the membranous portion is thin
where it is attached to the tip of the hook, but that it becomes much thicker below.
A small space near the bony portion of the tube, immediately below the hook,
remains permanently open, but elsewhere the walls are in contact, except when
separated by the action of the tensor palati muscle, or when forcibly driven asunder,
as in the act of sneezing, etc.
A number of small sesamoid fibro-cartilages, some of which are visible to the
naked eye, are buried in the submucous tissue.
The ossicles of the ear are described on pages 73-75.
Articulation of the Ossicles.-The malleus with the incus.
The oblong articular surface which descends as far as the neck, on the posterior
surface of the head of the malleus, is divided into two portions by a nearly vertical
edge. The incus presents a corresponding surface similarly divided into two por-
tions, and both of these surfaces are coated by a delicate layer of hyaline cartilage.
A thin capsule, from the inner surface of which a delicate wedge-shaped meniscus
projects from above into the cavity of the joint, is attached to the grooves, which
limit the articular surfaces. The mechanism has been compared by Helmholtz to
the check movement inside the key of a Geneva watch, and permits considerable
gliding between the two bones.
The incus with the stapes.-This joint is formed by the convex surface of the
lenticular process (orbicular bone) which terminates the long crus of the incus and
the corresponding concave surface of the head of the stapes. Both surfaces are
covered with a layer of hyaline cartilage.
The elastic capsular ligament permits but very slight separation between the



3 N
914
ORGANS OF SPECIAL SENSE
bones, but allows a somewhat freer lateral movement. This articulation has been
regarded by some writers as a synchondrosis, but it is now usually described as a
true joint.
The stapes with the margin of the fenestra ovalis.-The so-called annular
ligament is not equally broad throughout, and consists of elastic fibres which
radiate as they pass outwards from the edge of the footpiece of the stapes to the
margin of the fenestra. According to Toynbee, these edges are covered by a thin
layer of cartilage.
The Ligaments of the Ossicles. --In addition to the capsular ligaments already
described, certain well-marked bands limit the movements of the ossicles.
The superior ligament of the malleus descends as a firm rounded band from
the upper and outer wall of the tympanic cavity to the head of the malleus. It
limits the outward movement of the handle of the malleus.
FIG. 499.-SECTION OF THE TYMPANUM, ETC. (Enlarged.)

HEAD OF MALLEUS
Suspensory ligament
ATTIC OF THE TYMPANUM
External ligament
LONG CRUS OF INCUS
BASE OF STAPES-
HEAD OF STAPES
ORBICULAR BONE, OR
LENTICULAR PROCESS
EUSTACHIAN TUBE-
SHORT CRUS OF MALLEUS
HANDLE OF MALLEUS
EXTERNAL AUDITORY CANAL
Fibrous layer of
membrana tympani
CAVITY OF TYMPANUM
The anterior ligament of the malleus is broad and strong. According to
Helmholtz it encircles the long process of the malleus, and is inserted into the
fore part of its neck and head.
Some of the fibres of this ligament have been described as muscular under the
name of the laxator tympani muscle. But although occasionally muscular fibres
can be detected, in the majority of cases they appear to be absent.
The external ligament of the malleus prevents the handle of the malleus being
turned too much outwards. It passes from the margins of the notch of Rivini to
the short process of the malleus.
The ligament of the incus.-The short crus of the incus is covered with a layer
of fibro-cartilage and rests on a depression of the posterior tympanic wall, close
to the orifice leading into the mastoid cells. The posterior ligament binds the
process to this wall.
The Muscles of the Tympanum.-Two muscles-the tensor tympani and the

THE EAR
915
stapedius, both of which lie within bony canals-transmit their tendons into the
cavity of the tympanum for insertion into the chain of ossicles.
The tensor tympani is a penniform muscle about half an inch in length, and
arises in small part from the cartilaginous Eustachian tube and adjacent surface of
the sphenoid bone as well as from the wall of the canal in which it lies. The
tendon, which extends outwards almost at a right angle to the belly of the muscle,
can be traced some distance inwards on its lower aspect. It is inserted on the
inner margin of the handle of the malleus, near its root. The tendon glides
within a sheath continuous with the periosteum lining the canal and surrounded
by mucous membrane. This muscle draws the handle of the malleus, and with it
the membrana tympani, inwards.
The stapedius is a pyriform muscle, and arises from the interior of the
pyramidal eminence which projects from the posterior wall of the tympanum.
The tendon, which can be traced inwards for more than half the length of the
muscle, passes through the aperture at the summit of the eminence, to be inserted
into the posterior aspect of the neck of the stapes. Its tendon, like that of the
tensor tympani, is surrounded by a fibrous sheath enveloped in the tympanic
mucous membrane. This muscle depresses the posterior, whilst at the same time
it slightly raises the anterior, end of the foot-piece of the stapes.
Nerves. The stapedius is supplied by the facial nerve. The tensor tympani
receives a filament from the otic ganglion which is probably derived from the
motor portion of the fifth nerve.
The Mucous Membrane of the Tympanum is continuous through the Eustachian
tube with that which lines the pharynx. It is thin and transparent, and in places
it is easily detached.
Several vascular folds extend from the tympanic walls to the ossicles, all of
which receive a complete covering. The following are the most important.
(a) A prominent fold descends from the superior wall to the head of the
malleus and the upper margin of the body of the incus, and surrounds anteriorly
the tendon of the tensor tympani muscle.
(b) A second fold envelops the stapes, forming between its crura the so-called
obturator ligament of the stapes, and spreads posteriorly over its hinder crus to
envelop the tendon of the stapedius muscle.
(c) The folds which form the inferior boundaries of the so-called pouches of the
membrana tympani have already been described.
Other folds which are inconstant and irregular appear to be the shrunken
remains of the gelatinous connective tissue which fills the cavity in the foetal
state. The mucous membrane of the roof of the tympanum and that which lines
the membrana tympani and covers the ossicles possesses a flattened non-ciliated
epithelium. Elsewhere for the most part, including the Eustachian tube, it is
columnar and ciliated.
Vessels and nerves of the tympanum.-Arteries.-The tympanic branch of
the internal maxillary which passes through the Glaserian fissure, and the stylo-
mastoid branch of the posterior auricular which passes through the Fallopian
canal, supply the front and back part of the tympanic cavity, and form a
vascular chain around the circumference of the membrana tympani. In addition
to these chief branches the hiatus Fallopii transmits the petrosal branch from the
middle meningeal, whilst fine branches leave the carotid artery as it traverses the
carotid canal. The ascending pharyngeal sends branches to the Eustachian tube,
some of which reach the tympanum.
Veins. The veins empty into the superior petrosal sinus and into the temporo-
maxillary.
Nerves. The tympanic mucous membrane is supplied by the tympanic plexus
which occupies the grooves on the promontory and inner wall of the cavity.

3N2
916
ORGANS OF SPECIAL SENSE
The plexus is formed by the following nerves.
The tympanic branch of the glosso-pharyngeal, which enters the cavity
through a foramen in the floor; a communicating branch from the carotid plexus
of the sympathetic which passes through the carotid canal.
A branch from the great superficial petrosal, which enters by the inner wall
close in front of the fenestra ovalis; and one from the small superficial petrosal,
which enters near the canal for the tensor tympani.
The course of the chorda tympani nerve has already been sufficiently indicated
(pages 808, 912).
THE INTERNAL EAR, OR LABYRINTH
The INTERNAL EAR, or LABYRINTH, is the essential part of the organ of
hearing, and receives the terminations of the auditory nerve.
The Osseous Labyrinth is divided into three portions: the vestibule, the semi-
circular canals, and the cochlea-recesses hollowed in the substance of the petrous
portion of the temporal bone.
FIG. 500.-THE OSSEOUS LABYRINTH OF THE RIGHT SIDE.
(Modified from Soemmerring. Enlarged.)

Superior semicircular canal.
Posterior semicircular canal-
External semicircular canal-
Vestibule and fenestra ovalis
Ampulla
Ampulla
Ampulla
Second turn of cochlea
-Apex of cochlea
Fenestra rotunda
Commencement of first turn of the cochlea
The Vestibule lies between the cochlea and semicircular canals, on the inner
side of the tympanum. It is a laterally compressed ovoidal cavity, and is about
one-fifth of an inch in horizontal and vertical measurement.
The outer wall presents the fenestra ovalis filled with the foot-piece of the
stapes and its annular ligament. On its inner wall there is a small saucer-like
depression, the fovea hemispherica, perforated below and in front by several minute
orifices (macula cribrosa) for the filaments of the auditory nerve. Immediately
behind this is a vertical ridge, the pyramidal eminence or crista vestibuli, behind
which is the orifice of the aqueductus vestibuli.
On the roof there is a second depression, oval in shape, the fovea hemielliptica.
The two depressions are separated by the pyramidal eminence.
Behind, the semicircular canals open by five orifices; and in front by means of
a large oval opening the vestibular cavity communicates with the scala vestibuli
of the cochlea, the apertura scalæ vestibuli.
The Three Semicircular Canals are placed above and behind the vestibule. They
are unequal in length, but each forms the greater part of a circle, is laterally
compressed, and measures about one-twentieth of an inch (1.5 mm.) in diameter
(page 45). One extremity of each canal is suddenly dilated to nearly double its size

THE EAR
917
to form the ampulla. As two of the canals join to open by a common orifice,
collectively they present only five openings.
The superior semicircular canal, the highest of the canals, is almost vertical,
and is directed transversely. A smooth eminence on the anterior surface of the
petrous bone closely corresponds to the summit of its arch. Its ampullary end is
at the outer extremity, and presents a separate opening at the upper part of the
vestibule; the opposite end, which is not dilated, joins to form a common orifice
with the similar extremity of the posterior canal.
FIG. 501.--INTERIOR OF THE OSSEOUS LABYRINTH OF THE LEFT SIDE.
(Modified from Soemmerring. Enlarged.)

Fovea hemielliptica
Superior semicircular canal
Posterior semicircular canal
Fovea hemispherica -
Lamina spiralis
Scala tympani of-
the cochlea
External semicircular canal
Orifice common to the superior
and posterior semicircular
canals
-Orifice of the vestibular
aqueduct
-Orifice of the cochlear aqueduct
The posterior semicircular canal is the longest. Its dilated end is placed at
the lower and back part of the vestibule; its non-dilated extremity joins the
superior canal. It is placed nearly vertically, and is directed backwards.
The external semicircular canal curves horizontally outwards, and presents
two openings in the upper and back part of the vestibular cavity.
The Cochlea has a rough resemblance to a snail's shell, and coils itself almost
horizontally immediately in front of the vestibule. Its base corresponds to the
lower and front part of the fundus of the internal auditory meatus, and is there

FIG. 502.-INTERIOR OF THE OSSEOUS COCHLEA. (Enlarged.)
Scala vestibuli-
Scala tympani-
-Lamina spiralis
-Modiolus
marked by the series of minute holes which form the tractus spiralis foraminu-
lentus, whilst its apex is directed forwards and outwards, towards the upper
and
fore part of the inner wall of the tympanum.
The cochlea is about a quarter of an inch (6 mm.) in length, and its basal measure-
ment is nearly the same. It is composed of a central pillar, the modiolus, or columella,
around which curls for two and a half turns a spiral canal, which contains a
delicate spiral shelf or plate, the lamina spiralis. This partially divides its cavity
into two portions, as it follows its windings from base to apex. Near the apex
918
ORGANS OF SPECIAL SENSE

it ends in a hook-like process, the hamulus, which bounds a small opening, the
helicotrema. The osseous spiral canal is nearly an inch and a half (about 3.5 cm.)
in length. The lamina spiralis is thin and dense in structure at its edge, but it is
spongy and channelled with canals for nerves and blood-vessels where it starts
shelf-like from the modiolus.
The spiral canal of the modiolus coils round the pillar as it tunnels the base
of the spiral lamina.
In the recent state, membranous structures complete the bony partition into two
separate chambers, or scale: the scala vestibuli and the scala tympani, which
communicate through the helicotrema at the summit of the cochlea.
The scala vestibuli commences from the cavity of the cochlea; in its first turn
it is somewhat narrower than the scala tympani.
The scala tympani commences at the fenestra rotunda, which is filled with the
secondary membrane of Scarpa, and forms a kind of window which shuts it off
from the cavity of the tympanum. Near its commencement is the small orifice of
the aqueductus cochleæ, which lodges a minute vein, and forms a communication
with the subarachnoid space.
The central axis, or modiolus, extends from the base to the apex of the cochlea.
It starts with a broad base where it corresponds with the first turn of the cochlea,
and it is pierced by minute canals to receive the filaments of the cochlear division
FIG. 503.-SECTION OF THE OSSEOUS COCHLEA. (Enlarged.)

Lamina spiralis
Scala vestibuli
Lamina spiralis
Scala tympani
Modiolus
Central canal of the modiolus
Termination of external auditory meatus
of the auditory nerve. In the second coil the axis is diminished by more than
half, and it terminates in the remaining half coil or cupula in a bony plate, the
infundibulum, which expands towards the summit of the cochlea, with which it
becomes continuous. The central canal of the modiolus runs through its centre.
The Membranous Labyrinth, which lies within the bony labyrinth just described,
receives the terminations of the auditory nerve. It is for the most part separated by
the perilymph from the membrane which lines the bony chambers, and it contains
within its own cavity the fluid endolymph. In the vestibule and semicircular
canals it bears a near resemblance (though it is much smaller) to the enclosing
structures, but in the cochlea it not only divides its canal into the two scale, but
forms between them a third space, the canal of the cochlea.
Within the vestibule the membranous labyrinth consists of two sacs, which do
not directly communicate: the utricle, connected with the semicircular canals; and
the saccule, with the cochlea.
The Utricle is the larger. It is oblong, laterally compressed; it occupies the
upper and back part of the cavity, and is in contact with the fovea hemielliptica.
Filaments of the auditory nerve are distributed to the wall of the sac opposite the
crista vestibuli, passing through the bony foramina already described. Its wall is
here thicker than elsewhere, and calcareous particles (otoliths) are attached to its
inner surface. Behind, the cavity communicates by five orifices with the semi-
circular canals.

THE EAR
919
The Saccule, which is slightly flattened, occupies the front and lower part of the
cavity at the opening of the scala vestibuli of the cochlea. From the hollow of the
fovea hemispherica it receives numerous nerve filaments, and presents a thickened
area with attached otoliths.
The membranous canal of the cochlea is connected with the saccule by a short
canal, the canalis reuniens.
FIG. 504.-MEMBRANOUS LABYRINTH (MAGNIFIED), WITH NERVES.
(Modified from Breschet.)
Issige)

UTRICLE
BRANCH TO POSTERIOR
CANAL
SACCULE
BRANCH TO SACCULE
BRANCH TO COCHLEA-
BRANCH TO SUPERIOR AND
EXTERNAL CANALS
BRANCH TO UTRICL
FACIAL NERVE
FIG. 505.-ENLARGED DIAGRAMMATIC VIEW OF MEMBRANOUS LABYRINTH.
AMPULLA
AMPULLA AND
UTRICLE
SACCULE
SCALA MEDIA OF
COCHLEA
CANALIS
REUNIENS
AMPULLA
SUPERIOR
SEMICIRCULAR
CANAL
EXTERNAL
SEMICIRCULAR
CANAL
POSTERIOR
SEMICIRCULAR
CANAL
The two sacs are indirectly connected by means of a small tube which leaves
the saccule to join the commencement of a minute canal, as it passes from the
utricle to enter the aqueductus vestibuli.
Within each semicircular canal the membranous labyrinth occupies less than
a third of the area of the tube, but follows its curves and repeats its ampullary
enlargement; and here the wall is thicker and more opaque, and more completely
fills the cavity. The membranous ampullæ are flattened on their external walls,
920
ORGANS OF SPECIAL SENSE
where they receive vascular and nervous filaments, and their cavities are partially
divided by a transverse crest or ridge (crista acustica). Within the canal the outer
convex border is fixed to the osseous wall.
Structure. The membranous labyrinth consists of three layers: a tunica pro-
pria, with a fibrous investment externally, and an epithelial lining within.
Within the cochlea, the membranous structures divide the canal into three
compartments. The lamina spiralis (which in macerated specimens only partially
divides it) is continued into a projection from the periosteum of the outer wall
(spiral ligament) by means of a distinct membrane, membrana basilaris, thus
completely roofing in the scala tympani which before communicated with the
scala vestibuli. In addition, a delicate membrane, the membrane of Reissner,
stretches from the opposite surface of the lamina from near its free edge to the
periosteum of the outer wall. Shutting off a small triangular space (scala media)
from the scala vestibuli, the sides of which are bounded by the two membranes
(basilar and Reissner), and whose base externally is formed by the osseous wall
with its periosteal lining. This canal is lined with epithelium, winds through the
whole length of the cochlea, and is commonly known as the ductus cochlearis, or
FIG. 506.-ENLARGED VIEW OF LONGITUDINAL SECTION OF THE FIRST TURN OF THE
COCHLEA, SHOWING THE POSITIONS AND BOUNDARIES OF THE THREE SCALE.

MEMBRANE OF REISSNER
SCALA MEDIA
MEMBRANA BASILARIS
SCALA VESTIBULI
SPIRAL GANGLION
SCALA TYMPANI
membranous canal of the cochlea. It ends blindly by pointed extremities. That
which corresponds to the floor of the vestibule receives the small canal already
described, the canalis reuniens, which proceeds from the saccule. The canal of the
cochlea and the saccule are thus brought into communication.
The Auditory Nerve divides into two portions before it reaches the fundus of
the external auditory meatus.
The superior division consists of three branches which pass to the crista
vestibuli, through special openings, to be distributed to the utricle and the
ampullary enlargements of the superior and external semicircular canals.
The inferior division supplies the cochlea through the foramina of the tractus
foraminulentus; also a branch to the saccule, the filaments of which pass through
the openings of the fovea hemispherica; and a longer branch to the posterior
semicircular canal, which reaches it by a special channel behind the foramina
which transmit the filaments to the saccule.
Vessels. The internal auditory branch of the basilar artery, which accompanies
the auditory nerve, supplies both the vestibule and cochlea, with their membranous
contents. The veins correspond and open into the inferior petrosal sinus, which
also receives the minute veins which traverse the aqueductus vestibuli.


THE TONGUE
BY ARTHUR HENSMAN, F.R.C.S.
LECTURER ON ANATOMY AT THE MIDDLESEX HOSPITAL MEDICAL COLLEGE; AND SURGEON TO THE THROAT
AND EAR DEPARTMENT OF THE MIDDLESEX HOSPITAL.
The tongue is a freely movable, highly sensitive, and muscular organ, and is
endowed with the special sense of taste. It participates, moreover, in the function
of speech, and plays an important part in mastication and deglutition.
Its upper surface, or dorsum, with its sides and tip, are free, whilst its base is
attached by muscles to the hyoid bone and lower jaw. Folds of mucous membrane
loosely connect it with the epiglottis and soft palate, as well as with the symphysis
of the lower jaw. From beneath its rounded borders the mucous covering becomes
continuous with the inner surface of the gums. The anterior two-thirds of the
tongue occupies the floor of the mouth, lying between the halves of the lower jaw,
with its convex dorsum overarched by the vault of the palate, and its sides and tip
in contact with the teeth and gums. The posterior third of the dorsum forms a
rounded surface overhanging the epiglottis.
The mucous membrane, which is really a modified skin, covers the whole of the
free surface of the tongue. It forms three folds: the glosso-epiglottidean in con-
nection with the epiglottis; and on each side of the median fold-frænum epiglot-
tidis-is formed the glosso-epiglottidean pouch, or vallecula, which is bounded
externally by the more rounded lateral folds. On each side of the tongue, near the
junction of the posterior and middle third, the membrane ascends to form the
anterior pillars of the fauces, and in front beneath the tip it forms the sharp fold
of the frænum linguæ (fig. 509).
A slight longitudinal groove, the median raphe, divides the dorsum of the
tongue along its anterior two-thirds. It ends posteriorly near a small foramen,
the foramen cæcum, which represents the upper termination of the thyro-glossal
duct. The orifice, however, is not at all constant in the adult tongue, although
occasionally it is present, and may sometimes lead into the still patent duct which
tunnels the tongue as far as the body of the hyoid bone. The course of the
obliterated duct may in many cases be demonstrated.
The foramen cæcum is easily seen in the foetus at the angle of meeting of two
shallow grooves which form the V-shaped line behind the circumvallate papillæ.
This groove indicates the line of junction of the anterior and posterior portions of .
the tongue, and is faintly visible in the adult organ.
The papillæ crowd the anterior two-thirds of the dorsum as well as the sides
and tip of the tongue, but at the back they are small and hidden by the epithelial
coating. Of the papillæ three chief kinds can be distinguished.
The circumvallate or calyciform papillæ are the largest, but they are few in
number, varying from seven or eight to twelve, and they form a V-shaped line in
front of and parallel with the groove already mentioned.


922
ORGANS OF SPECIAL SENSE
Each papilla presents a narrow attached base and a broad free end, and is
seated in a circular cup which is surrounded by a rim or vallum.
Upon the bases of most of these papillæ a central depression marks the orifice
of one or more glands. Secondary papillæ lie hidden under the thick epithelial
covering both of the chief papilla and the circular rim which surrounds it.
The fungiform papillæ are more thinly covered with epithelium, and they are
redder in colour than the smaller papillæ amongst which they are scattered. They
occur irregularly over the dorsum, sides, and tip of the tongue, being attached by a
FIG. 507.-DORSUM OF THE TONGUE.

EXTREMITY OF CORNU OF
HYOID BONE
SUPERIOR CORNU OF THYROID
CARTILAGE
LATERAL GLOSSO-
EPIGLOTTIDEAN FOLD
False vocal cord
LOWER END OF PHARYNX
-ANTERIOR WALL OF THE
PHARYNX
CORNICULUM LARYNGIS
CUNEIFORM CARTILAGE
SINUS PYRIFORMIS
True vocal cord
EPIGLOTTIS
MEDIAN GLOSSO-
EPIGLOTTIDEAN FOLD
TONSIL
ADENOID TISSUE AT BACK OF
TONGUE
POSTERIOR PILLAR OF FAUCES
ANTERIOR PILLAR OF FAUCES
FORAMEN CECUM
CIRCUMVALLATE PAPILLÆ
FUNGIFORM PAPILLÆ
comparatively narrow base with a broader, rounded, and free extremity, and, like
the circumvallate, are studded with smaller secondary papillæ.
The filiform or conical papillæ, named from their general shape, thickly beset
the whole of the dorsum, sides, and tip of the tongue in front of the circumvallate
group. They faintly ridge the organ with delicate lines, which posteriorly lie
parallel with the circumvallate papillæ, but become more and more transverse in
direction as they approach the tip and sides of the tongue. They present secondary
papillæ upon their surfaces thickly overlaid with epithelium.

THE TONGUE
923
The lingual glands are especially abundant near the foramen cæcum and in
the neighbourhood of the circumvallate papillæ, as well as along the borders of the
tongue.
FIG. 508.-THE FETAL TONGUE.

SUPERIOR APERTURE OF GLOTTIS
POSTERIOR ROUNDED PORTION OF TONGUE
DORSUM
LOWER PART OF PHARYNX
FORAMEN CECUM
GROOVE DIVIDING ANTERIOR AND POSTERIOR
PORTIONS OF TONGUE
CIRCUMVALLATE PAPILLÆ
FIG. 509.-UNDER SURFACE OF THE TONGUE WITH MUSCLES.

FRÆNUM LINGUÆ
Lingualis inferior
Lingualis inferior
Hyo-glossus
Genio-hyo-glossus
Genio-hyoid
Stylo-glossus
-Hyo-glossus
BODY OF HYOID BONE
Mylo-hyoid, reflected
Sterno-hyoid
Genio-hyoid
THYROID CARTILAGE
A special group forms an elongated mass, the gland of Nuhn, on either side of
organ, and just beneath its tip. It occupies the groove between the genio-hyo-
glossus muscle and the inferior lingualis.
the

924
ORGANS OF SPECIAL SENSE
FIG. 510.-TRANSVERSE SECTION THROUGH THE LEFT HALF OF THE TONGUE.
(Magnified.)
(From a preparation by Mr. J. Pollard, Middlesex Hospital Museum.)
Transverse muscular fibres
PAPILLE-
Superior lingual-
muscle
Septum-
Inferior lingual
muscle, mixed
with extrinsic
fibres
Vertical muscular fibres
FIG. 511.-SIDE VIEW OF THE TONGUE, WITH ITS MUSCLES.
Genio-hyo-glossus
Genio-hyoid
DORSUM OF TONGUE
CO
9300
Cut edge of mylo-hyoid
BODY OF HYOID BONE
Stylo-glossus
Submucous
tissue
STYLOID PROCESS
Stylo-hyoid
POSTERIOR PORTION OF
TONGUE
Stylo-pharyngeus
Hyo-glossus
Thyro-hyoid ligament
CARTILAGO TRITICEA
Thyro-hyoid membrane
EPIGLOTTIS
(indicated by dotted lines)
THYROID CARTILAGE
GREATER CORNU OF HYOID BONE
Median portion of
crico-thyroid
membrane
CRICOID CARTILAGE
FIRST RING OF TRACHEA
THE TONGUE
925
The mucous membrane of the posterior third of the tongue contains abundant
lymphoid tissue, collected into rounded masses. This often becomes much
developed, and gives to this part of the tongue an irregular nodular appearance.
A fibrous septum separates the halves of the tongue and extends in the middle
plane from base to apex; and a strong fibrous membrane, the hypoglossal membrane,
passes from beneath the base of the tongue to the body of the hyoid bone.
The Muscles of the Tongue.-The muscles of the tongue are both extrinsic,
and special or intrinsic.
The extrinsic muscles are the hyo-glossus, genio-hyo-glossus, stylo-glossus,
palato-glossus, and a small part of the superior constrictor.
The intrinsic muscles. The lingualis superior constitutes a superficial longi-
tudinal stratum, which extends from the base to the tip of the organ, immediately
beneath the mucous membrane. The fibres form short fascicles attached to the
overlying tissues, and are placed between the hyo- and stylo-glossi muscles of the
opposite sides of the tongue, both pairs of which, near the base, overlap the fibres
of the lingualis.
The inferior lingualis is composed of two bands which reach from the base to
the apex on the under surface of the tongue. Posteriorly some of the fibres become
attached to the body of the hyoid bone. Each of these bands is placed between
the hyo- and genio-hyo-glossus, and near the tip some of its fibres mix with those
of the stylo-glossus muscle.
The transverse fibres mixed with fat lie between the two muscles just described,
and form a considerable part of the bulk of the tongue. They take origin from
the median fibrous septum, and, curving outwards and upwards, are inserted into
the sides and dorsum of the organ.
The vertical fibres decussate with the transverse, and pass from the dorsum to
the under surface of the tongue in curves with their concavities looking outwards.
The fibres become shorter as they approach the margin of the tongue.
Arteries. The arteries are derived from the lingual, facial, and ascending
pharyngeal.
Nerves.-The nerves are the lingual branch of the mandibular division of
the fifth, which supplies the papillæ of the fore part and sides of the tongue; the
lingual branch of the glosso-pharyngeal, which supplies the base and sides, in-
cluding the circumvallate papillæ; and fine branches from the superior laryngeal,
which reach the root close to the epiglottis.
The hypoglossal supplies the muscular substance of the tongue, as well as most
of the extrinsic muscles; and the chorda tympani through the facial contributes
also some filaments.


THE NOSE
BY ARTHUR HENSMAN, F.R.C.S.
LECTURER ON ANATOMY AT THE MIDDLESEX HOSPITAL MEDICAL COLLEGE; AND SURGEON TO THE THROAT
AND EAR DEPARTMENT OF THE MIDDLESEX HOSPITAL.
The nose includes a visible external portion, the nose proper; and an internal
cavity, the nasal fossa.
The Nose Proper is triangular in shape; its root above is at the forehead, from
which the bridge or dorsum slopes downwards and forwards to end in a rounded tip
or lobe. The base below overhangs the upper lip; it here presents two orifices,
the nostrils, which are divided by the columna.
FIG. 512.-SIDE VIEW OF THE NOSE, SHOWING ITS CARTILAGES, ETC.

NASAL BONE
NASAL PROCESS OF THE MAXILLA
UPPER LATERAL CARTILAGE
CARTILAGE OF SEPTUM
OUTER PLATE OF LOWER LATERAL
CARTILAGE
ACCESSORY QUADRATE CARTILAGES
Fibrous tissue
SESAMOID CARTILAGES
INNER PLATE OF LOWER LATERAL
CARTILAGE
CELLULAR TISSUE FORMING ALA
The nostrils are protected by stiff hairs, and each opens into a cavity, extending
a little above the cartilages, called the vestibule. Its sides slope from the dorsum
outwards and backwards, and terminate below in the alæ or wings, which bound
the nostrils externally. It presents a dense unyielding bony framework, formed
by the two nasal bones, with the nasal processes of the maxillæ above, and by the
projecting anterior nasal spine below. To this is added a yielding cartilaginous
portion, which completes the organ, forming its chief part.
THE NOSE
927
The nose is enveloped in skin, lined by a mucous membrane, and supplied with
vessels and nerves, and its cartilages are acted upon by small muscles.
The cartilages.-The principal cartilages are five in number: a pair above, the
superior lateral; a pair below, the inferior lateral; and the cartilage of the septum,
the persistent unossified remnant of the facial segment of the chondro-cranium
(page 97). With these must be included a group of small irregular cartilages
known as sesamoid and accessory quadrate.
These cartilages, ensheathed in perichondrium, are for the most part loosely
held together by tough intervening fibrous tissue, and this in turn becomes con-
tinuous with the periosteum of the surrounding bones.
The upper lateral cartilages are nearly flat and somewhat triangular in shape,
each presenting an outer and an inner surface.
Their anterior margins are continuous above with the rounded borders of a
shallow groove which furrows the cartilage of the septum; but below for about two-
thirds of their extent, though their edges are closely applied to the borders of the
FIG. 513.-ANTERIOR VIEW OF THE NOSE, SHOWING ITS CARTILAGES, ETC.

ORIFICE OF LACHRYMAL CANAL
NASAL BONE
NASAL PROCESS OF THE MAXILLA
GROOVE ON ANTERIOR BORDER OF
SEPTAL CARTILAGE
ACCESSORY QUADRATE CARTILAGES-
SESAMOID CARTILAGES
UPPER LATERAL CARTILAGE
CELLULAR TISSUE OF ALA-
OUTER PLATE OF LOWER LATERAL
CARTILAGE
groove, there is on each side a narrow cleft of separation which opens out below
into an angular notch.
Their curved posterior margins are firmly attached superficially by somewhat
jagged edges to the nasal bones; but deeply, and especially near the septum, they
underlie these bones for a considerable distance.
The rest of the border is smooth, free, and loosely connected by intervening
fibrous tissue to the nasal process of the maxilla.
Their inferior borders are connected with the lower lateral cartilages; one or
more narrow plates of cartilage occasionally intervene and fill the fibrous interval.
On account of their continuity with the septal cartilage, the upper lateral cartilages
should be regarded as its wings or lateral expansions. (Henle.)
The lower lateral cartilages are thin, pliant, and curved, and so folded back-
wards that each forms an inner and outer plate.
The inner plates are loosely attached to one another, where they meet below
the septum to form the tip of the nose and fore part of the columna.
The outer plates are oval, and curve backwards above the masses of dense
cellular tissue which form the alæ. They maintain the contour of the nostrils,


928
ORGANS OF SPECIAL SENSE
and serve to keep these orifices open. Posteriorly they are connected by fibrous
tissue to the nasal margin of the superior maxillaries.
In this tissue are embedded several extremely thin and irregular cartilages named
sesamoid, and above these commonly a pair still smaller, called accessory quadrate.
The septal cartilage fills in the triangular interval of the bony septum. The
anterior border is attached to the nasal bones at their junction below the crest.
Beyond it presents a shallow groove, the borders of which are at first continuous
with the upper lateral cartilages, as already described. This groove becomes
narrowed by the gradual approximation of its borders, which ultimately meet in a
faint transverse ridge which terminates it below. Still lower, it dips for a short
distance between the inner plates of the lower lateral cartilages, beyond which
these meet to form the tip of the nose.
The posterior border is connected with the perpendicular plate of the ethmoid,
whilst its inferior is attached to the vomer, which is often channelled like the
ethmoid plate to receive it. Immediately in front it is attached to the nasal spine
of the maxillæ.

FIG. 514.-UNDER VIEW OF THE NOSE, SHOWING ITS CARTILAGES, ETC.
SEPTAL CARTILAGE
OUTER PLATE OF LOWER LATERAL
CARTILAGE
INNER PLATE OF LOWER LATERAL
CARTILAGE
NASAL SPINE OF THE MAXILLA-
SEPTAL CARTILAGE
Cellular tissue of ala
The cartilage does not simply dip into the groove which is more or less marked
on the upper surface of the nasal spine, but broadens out to obtain the widest
possible, though somewhat lax, attachment to it. Viewed from below, it appears
to embrace the spine. The border of its rounded angle in front is somewhat
thickened before terminating in a thin smooth edge. It is extremely thin near the
centre.
The shape of the septal cartilage varies in relation to the extent of ossification
in the bony septum, and even in the adult a strip of cartilage may extend for a
varying distance backwards and upwards between the vomer and ethmoid, sometimes
even reaching the body of the sphenoid bone.
It may be here noted that the septum of the nose is almost always straight in
children and in aboriginal skulls (eighty per cent.); but in Europeans it is deflected
to one or other side in the proportion of three out of every four.
Jacobsonian cartilages.- In the septal cartilage above the opening of Stenson's
canal there is a small pouch which presents a minute opening below. This is the
representative of the Jacobsonian organ. A strip of cartilage underneath this,
firmly adherent, but distinct from the septal cartilage, is known as the Jacobsonian
cartilage.
THE NOSE
929
Muscles.-The muscles are seven in number, and may be grouped as dilators
and constrictors. The latter are comparatively feeble in their action.
The dilators.-The pyramidalis nasi is a downward prolongation of the occipito-
frontalis. Each muscle descends on the side of the nose, to blend, after becoming
tendinous, with the compressor nasi. They diverge from one another as they pass
downwards. The levator labii superioris alæque nasi arises from the nasal process
of the maxilla.
It divides in its passage downwards, one slip being inserted into the cartilage of
the wing, the other extending to the upper lip to blend with its muscular fibres.
The two foregoing muscles may be regarded as extraordinary or reserve muscles
of dilatation.
FIG. 515.-SECTION SHOWING BONY AND CARTILAGINOUS SEPTUM.
The dotted line indicates the course of the anterior palatine canal.
NASAL BONE
Frontal sinus

UPPER LATERAL CARTILAGE
Groove between septal
and upper lateral
cartilage
LOWER LATERAL
ETHMOID
VOMER
Sphenoidal sinus
THICKENED BORDER OF CARTILAGE RESTING
Move
Pouch at upper extremity
of Stenson's canal
UPON ANTERIOR NASAL SPINE Incisive papilla
SEPTAL CARTILAGE
ORIFICE OF EUSTACHIAN
TUBE
SOFT PALATE
The dilator naris consists of two small muscular slips, requiring a lens for
their proper demonstration; in some cases they are absent.
The dilator naris anterior is a small and indistinct muscle. It is placed
between the skin and cartilage of the ala.
The dilator naris posterior arises from the edge of the nasal notch of the
maxilla and the sesamoid cartilages, to be inserted into the margin of the nostril.
In paralysis of the facial nerve, a deep inspiration through the nostril produces
complete collapse of its cartilaginous wall, thus showing the importance of the
dilator muscles in keeping patent the nasal orifices.
The constrictors, or compressors.-The compressor naris arises from the
maxilla near the incisive fossa, its fibres mixing with those of the levator
anguli oris. It expands as it passes inwards, to end in a thin aponeurosis, which
30
930
ORGANS OF SPECIAL SENSE
joins with its fellow as well as with the pyramidalis, and it also blends with the
subcutaneous tissue over the bridge of the nose.
The depressor alæ nasi arises from the incisor fossa; its fibres pass upwards
to the septum and posterior part of the wing.
The compressor narium minor consists of a few indistinct fibres, occasionally
found between the alar cartilage and skin over the tip of the nose.
These muscles are all supplied by the facial nerve.
The skin covering the nose is for the most part thin and freely movable upon
the subjacent parts, but at the tip and over the cartilages it is much thicker and
more adherent and furnished with numerous sebaceous glands.
The mucous membrane becomes continuous with the skin at the nasal orifices,
and posteriorly with the membrane which lines the nasal fossæ.
FIG. 516.-MUSCLES OF THE NOSE. (After Bourgery.)

Levator labii superioris
alæque nasi
Accessory slip of compressor-
naris
-Occipito-frontalis
-Pyramidalis nasi
-Compressor naris
Dilator naris posterior-
-Dilator naris anterior
-Compressor narium minor
Orbicularis oris.
The vessels. The arteries of the nose which arise from the facial are the
lateralis nasi and the artery to the septum derived from the coronary of the same
trunk. This latter also supplies the ala. The nasal branch of the ophthalmic
and infraorbital are distributed to the sides and dorsum.
The veins terminate by joining the facial and ophthalmic.
The nerves. The nerves are supplied by the facial, which is motory, and by the
infratrochlear and nasal branch of the ophthalmic division of the fifth, which are
sensory.
The nasal fossæ.-The nasal fossæ have been already described (page 86).
Tho mucous membrane (pituitary or Schneiderian).-In the recent state the
area of the fossæ is much contracted by its mucous lining. This is loosely folded
around the lower edges of the turbinal bones, and extends beyond them in front
and behind. Especially is this marked where it envelops the inferior turbinal
bone, and it is here very thick and spongy. It is, moreover, thick where it covers
THE NOSE
931
the septum, but thin at the bottom of the meatuses and within the sinuses.
Some of the openings which are apparent in the dried skull are quite hidden in
the recent state; those, however, which lead into the air-spaces together with the
lachrymal duct remain patent, though the bony orifices are much reduced in size.
There is a small conical closed sac, close to the septum at its fore part, which
indicates the position of the now obliterated canal of Stenson. The termination is
marked in the mouth by the incisive papilla. The membrane is continuous in
front through the anterior nares with the skin; behind, it extends through the
posterior nares to line the naso-pharynx and tympanum with the mastoid cells by
way of the Eustachian orifice and tube. It is intimately adherent to the periosteum
and perichondrium. The acinous glands which are imbedded in its structure
secrete for the most part a thin watery fluid. They are especially large over the
FIG. 517.-OBLIQUE SECTION PASSING THROUGH THE NASAL FOSSE, JUST IN FRONT
OF THE POSTERIOR NARES. (Seen from behind.)

Front wall of left.
sphenoidal sinus
with orifice below
Orifice of right
sphenoidal sinus
SUPERIOR TURBINAL
BONE
CRISTA GALLI
A closed anterior
ethmoidal cell
ANTERIOR ETHMOIDAL
CELLS
MIDDLE TURBINAL BONE
RIGHT ANTRUM WITH
ORIFICE
INFERIOR TURBINAL
BONE
ORIFICE OF EUSTACHIAN-
TUBE
UPPER SURFACE OF-
SOFT PALATE
-ORIFICE OF EUSTACHIAN
TUBE
inferior turbinal bone, and very numerous at the middle and back of the fossæ near
the orifices of the posterior nares.
The vestibule is lined with a scaly epithelium, behind which the cavity is
divided into an upper olfactory and a lower or respiratory region. The
olfactory region is lined with a columnar unciliated epithelium. The mucous
membrane is here of a yellowish colour, thicker than elsewhere, and contains the
olfactory cells of Max Schultze.
The lower or respiratory is a much wider portion, in which the epithelium is
columnar and ciliated, and includes the inferior turbinal bone with the lower
part of the fossa.
The roof presents but one opening posteriorly which leads into the sphenoidal
sinus. The orifices in the cribriform plate are entirely closed over.
302
932
ORGANS OF SPECIAL SENSE
FIG. 518.-SECTION OF THE NOSE, SHOWING THE TURBINAL BONES AND MEATUSES,
WITH THE OPENINGS IN DOTTED OUTLINE.

Orifice of middle ethmoidal cells
SUPERIOR TURBINAL BONE
Orifice of the posterior ethmoidal cells
Orifice of the sphenoidal sinus
Sphenoidal sinus
Frontal sinus
Orifice of frontal sinus
UPPER ORIFICE OF
NASAL DUCT
ORIFICE OF EUSTACHIAN
TUBE
LOWER ORIFICE OF NASAL DUCT
MIDDLE TURBINAL BONE
ORIFICE OF INFUNDIBULUM
INFERIOR TURBINAL BONE ORIFICE OF THE ANTRUM
FIG. 519.-TRANSVERSE SECTION PASSING THROUGH THE NASAL FOSSE AND ANTRA AT THE
POSTERIOR EXTREMITY OF THE MIDDLE TURBINAL BONE. (Seen from the front.)
Frontal sinuses
MIDDLE TURBINAL
BONE
NASAL SEPTUM
RIGHT ANTRUM
INFERIOR TURBINAL
BONE
THE NOSE
933
In the floor the openings leading into the anterior palatine canal are closed.
The small cul-de-sac already described indicates their position.
The superior meatus has but a single opening, which leads into the posterior
ethmoidal cells. The spheno-palatine foramen is entirely covered by membrane.
The middle meatus presents the orifice of the antrum. In front of this and
hidden by the overhanging turbinal bone is the curved gutter-like cell leading
upwards from the fore part of the meatus to the frontal sinus, the infundibulum.
It receives below the orifice of the middle, and above that of the anterior ethmoidal
cells.
In the inferior meatus is the orifice of the nasal duct. The opening is under
cover of the fore part of the inferior turbinal bone. The mucous membrane
is arranged around the opening in a circular valve, which is sometimes double,
known as the valve of Hasner (page 906).
FIG. 520.-NERVES OF THE NASAL CAVITY.
NASAL OLFACTORY

Frontal sinus NERVE
NERVE
OLFACTORY
NERVE TO SUPE
RIOR TURBINATE
BONE
Sphenoidal sinus
VIDIAN NERVE
MECKEL'S
GANGLION
DESCENDING
PALATINE
LORIFICE OF EUSTACHIAN
TUBE
NASAL BRANCHES
POSTERIOR
PALATINE
-ANTERIOR
PALATINE
MIDDLE
PALATINE
The nerves.-The olfactory or special nerves of smell, the filaments of which
pass through the foramina in the cribriform plate of the ethmoid bone, lie for some
distance in the grooves of the bony walls before terminating in the Schneiderian
membrane.
Those which supply the septum ramify in its upper third, whilst those which
reach the outer walls are distributed in two groups-a posterior, to supply the
membrane covering the superior turbinal bone, and an anterior to ramify in the
membrane over the middle turbinal bone and the smooth surface of the ethmoid
in front of this.
In addition to the special nerves of smell, the cavity is supplied with nerves of
common sensation derived from the fifth pair.
The nasal branch of the ophthalmic supplies the front and upper part of the
septum and also the outer wall of the nasal fossa.
934
ORGANS OF SPECIAL SENSE
The Vidian, with the upper anterior branches of Meckel's ganglion, supply the
upper and back portion of the septum, including the superior spongy bone.
The naso-palatine supplies the middle portion of the septum.
The anterior dental branch of the maxillary division of the fifth nerve is
distributed to the inferior meatus and inferior turbinal bone.
The anterior or large palatine nerve supplies in its course downwards the
middle and lower turbinal bones.
The arteries are distributed as follows:-
The spheno-palatine, from the internal maxillary by its internal or naso-palatine
branch, supplies the septum as it courses to the incisor foramen. Its external
branches supply the antrum (also supplied by the alveolar branch of the facial)
and frontal sinus, the ethmoidal cells, and inner surfaces of the turbinal bones
with the meatuses. It enters the cavity through the spheno-palatine foramen.
The anterior and posterior ethmoidal arteries derived from the ophthalmic
supply the upper portion of the septum, the roof, the outer wall (anteriorly) and
posterior ethmoidal cells.
The descending palatine of the internal maxillary sends a few filaments to the
back of the inferior meatus and lower turbinal bone.
The branch to the septum derived from the superior coronary of the facial
ramifies in the membrane covering its lower and front portion.
The veins form a plexus especially marked at the lower and hinder portions of
the fossa. They follow the course of the arteries. The spheno-palatine passes
into the pterygoid plexus. The ethmoidal terminate in the ophthalmic vein, and
the alveolar joins the facial.
Communications are formed with the veins within the cranial cavity, through
the cribriform foramina and foramen cæcum, and also with the facial vein through
small foramina in the nasal bone and nasal process of the maxilla.
The lymphatics form a well-developed plexus, which communicates, through the
lymphatics surrounding the olfactory nerves, with the subdural space within the
cranial cavity.
SECTION VII
THE THORAX
INCLUDING THE ORGANS OF VOICE,
RESPIRATION, AND CIRCULATION
BY ARTHUR HENSMAN, F.R.C.S.
LECTURER ON ANATOMY AT THE MIDDLESEX HOSPITAL MEDICAL COLLEGE; AND SURGEON TO THE THROAT
AND EAR DEPARTMENT OF THE MIDDLESEX HOSPITAL.
THE
THE THORAX
HE thorax, or trunk of the body-lying between the neck and the abdomen-is
formed partly of bones and partly of soft connecting tissues. In the living body
it is constantly varying in relation to the respiratory process. The cavity is bounded,
in front by the sternum and upper six costal cartilages and internal intercostal
muscles; behind by the thoracic vertebræ and posterior ends of the ribs; and
laterally by the ribs with the internal and external intercostal muscles.
Its form is conical, flattened in the adult from before backwards, so that its
transverse is its greater diameter. In the human foetus, as in the lower animals,
it is flattened laterally, its antero-posterior diameter being the greater.
It is narrow above, where the ribs are short, and broad below. Owing to
the backward set of the hinder extremities of the ribs, the bodies of the vertebræ
project forwards into the cavity, which thus, on a transverse section, appears more
or less cordiform.
The superior aperture is bounded, in front by the upper margin of the sternum;
behind by the body of the first thoracic vertebra; on each side by the first rib.
It measures in a well-formed adult about two and a quarter inches from before
backwards, and four and a quarter inches from side to side. The ribs slope down-
wards towards the sternum, the upper margin of which corresponds to the inter-
vertebral substance between the second and third thoracic vertebræ. It transmits
the following structures :-(1) The sterno-hyoid and sterno-thyroid muscles, and more
deeply a thin layer of the deep cervical fascia which blends below with the sheath
of the great vessels and the pericardium; (2) the thymus gland in the infant, or its
shrunken remains in the adult; (3) an occasional middle thyroid artery, the trachea,
the œsophagus, the thoracic duct, the longus colli muscles, and a thin layer of fascia
overlying them. Laterally: the innominate artery (on the right side), the common
carotid and subclavian (on the left), with the internal mammary and superior
intercostal arteries; the innominate and inferior thyroid veins; the phrenic,
pneumogastric, and sympathetic nerves, with the left recurrent laryngeal, some
cardiac branches, and the anterior branches of the first thoracic nerve. On each
side, in addition, there is a small portion of the apex of the lung with its pleural
covering.

936
THE THORAX
The lower opening, or base, is limited in front by the ensiform cartilage, behind
by the twelfth thoracic vertebra, and laterally by the twelfth ribs.
The diaphragm arches upwards to form a vaulted floor to the intervening space.
It is about one inch higher on the right side than on the left, and its flattened
central portion is lower than either of the lateral arches. The thoracic cavity is
much deeper behind than in front.
The following structures pass through the lower opening of the thorax :-(1) The
aorta, vena azygos major, thoracic duct, and, occasionally, the left sympathetic
nerve pass through the aortic opening. (2) The oesophagus, pneumogastric nerves, and
some small œsophageal arterial branches emerge through the oesophageal opening.

FIG. 521.-ANTERIOR VIEW OF THE THORAX, WITH OUTLINES OF THE
DIAPHRAGM AND LUNGS.
X
XI
XHO
VI
IV
У
VE
VIL
X
XI
XII
(3) The vena cava inferior ascends through the caval opening, and the branches
of the phrenic nerves pierce the diaphragm to reach its lower surface.
(4) The splanchnic nerves, the vena azygos minor, and the sympathetic trunk of
each side pass through the crura.
The viscera contained within the thoracic cavity are: the heart, which is enclosed
in the pericardium; and the lungs, with their pleural investments.
The heart lies between the lungs in the so-called mediastinal space. This is
bounded on each side by the reflexions of the pleuræ, which pass from the front to
the back of the thoracic cavity; and the common space is further subdivided into
a superior mediastinum above the heart sac, an anterior and a posterior respec-

SUPERIOR MEDIASTINUM
937
tively in front of and behind it, and a middle mediastinum which contains the
heart itself.
The superior mediastinum has the following boundaries:-the manubrium
with the origins of the sterno-hyoid and sterno-thyroid muscles in front; the bodies
of the four highest thoracic vertebræ behind, with the lower portions of the longus
colli muscles; and on each side the pleural sacs. Above, the boundary corresponds
with the superior aperture of the thorax, and below with a nearly horizontal plane
passing backwards from the articulation between the manubrium and gladiolus of
the sternum, to the lower part of the body of the fourth thoracic vertebra. This
FIG. 522. SUPERIOR VIEW OF A SECTION OF THE THORAX, PASSING THROUGH THE STERNUM
IMMEDIATELY BELOW THE FIRST COSTO-STERNAL ARTICULATION, THROUGH THE TRACHEA
AT ITS DIVISION, AND THROUGH THE BODY OF THE FOURTH THORACIC VERTEBRA.
(Braune.)
Arch of aorta
PHRENIC NERVE
STERNUM
POSTERIOR SURFACE OF STERNUM
Vena cava superior
PHRENIC NERVE
SECOND COSTAL CARTILAGE
VAGUS NERVE
Axillary vein
M.
Cu
LEFT
UNG
RIGHT
LUNG
SECOND COSTAL CARTILAGE
Axillary vein
THIRD RIB
SCAPULA
SYMPATHETIC NERVE
FOURTH RIB
LEFT RECURRENT
NERVE
CESOPHAGUS
SCAPULA
THIRD RIB
FIFTH RIB
Intercostal veins
VAGUS NERVE
FOURTH RIB
BODY OF FOURTH THORACIC
VERTEBRA
lower plane nearly corresponds with the upper part of the pericardium and roots of
the lungs.
The superior mediastinum contains the thoracic portion of the trachea,
œsophagus, thoracic duct, the transverse part of the arch of the aorta, the
innominate artery, thyroidea ima, and thoracic portions of the left carotid and left
subclavian; the innominate veins and upper part of the superior vena cava; the two
pneumogastric nerves, with the left recurrent, the phrenic and cardiac nerves; the
thymus gland or its remains, and some bronchial lymphatic glands, with the
superior sterno-pericardiac ligaments.
938
THE THORAX
The middle mediastinum contains the heart, the ascending portion of the arch
of the aorta and the pulmonary artery, the superior vena cava (lower half), all of
which are placed within the pericardium; and in addition the phrenic nerves and
their companion arteries, the termination of the azygos vein, the roots of the lungs,
with some bronchial lymphatic glands.
The anterior mediastinum is narrow above, lying behind the sternum opposite
the second, third, and fourth cartilages. Below, it opens out into a quadrangular
space, having nearly the whole of the lower half of the sternum, the lower edge of
the fourth, the fifth, part of the sixth, and the termination of the seventh cartilages
of the left side, with the triangularis sterni muscle in front (fig. 521.) The pericardium
forms its posterior wall. The space merely contains some small lymphatic glands
and areolar tissue, and a few irregular bands, the inferior sterno-pericardiac
ligaments, with the thymus gland or its vestiges. It corresponds to the area of
cardiac dullness.
The posterior mediastinum is bounded in front by the roots of the lungs and
posterior surface of the pericardium in front, and behind by the thoracic vertebral
column below the fourth thoracic vertebra. On each side it is bounded by the
pleural sacs. It contains the third part of the aortic arch and the descending aorta,
œsophagus, and pneumogastric nerves, azygos veins, thoracic duct, and lymphatic
glands.
THE ORGANS OF VOICE
THE LARYNX
The larynx is the organ of the voice, and the protector of the air passages from
the intrusion of foreign bodies. By its closure, moreover, it retains the air within the
chest cavity, contributing to the fixity of the thorax, a condition which is essential
to the due performance of a variety of muscular actions.
It consists of a framework of cartilages held together by ligaments and acted
upon by muscles (extrinsic and intrinsic). It is lined by a very sensitive mucous
membrane, and supplied with blood-vessels, nerves, and lymphatics.
The cartilages of the larynx are nine in number.
some are arranged in pairs.
Single cartilages:-
Thyroid.
Cricoid.
Epiglottis.
Some of these are single,
Paired cartilages :-
Arytenoid.
Cornicula laryngis (Santorini).
Cuneiform (Wrisberg).
From their general structure they may be arranged as follows:--
Hyaline :-
Thyroid.
Cricoid.
Yellow elastic:-
Epiglottis.
Cornicula laryngis.
Cuneiform.
Arytenoid (the tip of the arytenoid
is yellow elastic.)
In the anteater there extends backwards from each side of the epiglottis to the
summit of the arytenoids a continuous rim of yellow elastic cartilage. It is the broken
remnants of this which in man form the cornicula and the cuneiform cartilages. (Bland
Sutton).


THE LARYNX
939
The THYROID CARTILAGE forms the front and sides of the upper part of the
larynx, being placed above the cricoid. It consists of two nearly square symmetrical
plates, or alæ, united in front, where they form the pomum Adami, but widely
separated behind. They include between them an angle varying from 80° to 90°, and
are somewhat obliquely inclined, their outer surfaces looking slightly downwards as
well as outwards. Each plate has an outer and an inner surface and four borders.
The upper and lower angles of each plate project upwards and downwards to form
posteriorly its superior and inferior cornu.
The outer surface is smooth, and is crossed by an oblique and often very faintly
defined line, or by an occasional fibrous band. This is marked at each extremity
by a small tubercle. These tubercles are more pronounced in old subjects. The
FIG. 523.-FRONT VIEW OF THE CARTILAGES OF THE LARYNX.
(Modified from Bourgery and Jacob.)
BODY OF HYOID BONE
Thyro-hyoid ligament.
Cartilago triticea
Foramen for superior
laryngeal nerve
Median portion of thyro-
hyoid membrane
SUPERIOR CORNU OF THYROID
CARTILAGE
MEDIAN NOTCH OF THYROID
CARTILAGE
Pomum Adami
THYROID
CARTILAGE
OBLIQUE LINE OF THYROID
CARTILAGE
Crico-thyroid membrane.
INFERIOR CORNU OF THYROID.
CARTILAGE
CRICOID
CARTILAGE
THIRD RING OF TRACHEA
-OBLIQUE LINE BELOW SUPERIOR
TUBERCLE
WING OF CARTILAGE BEHIND
OBLIQUE LINE
OBLIQUE LINE ABOVE INFERIOR
TUBERCLE
-ANTERIOR BORDER OF INFERIOR
CORNU
line and the adjacent cartilage give attachments to the thyro-hyoid and sterno-
thyroid muscles, and the smaller portion (one fourth) of the ala which lies behind
it is overlapped by the inferior constrictor, this muscle arising from its anterior part.
The inner surface is also smooth; it is concave, and in contact with the mucous
membrane which lines the sinus pyriformis.
The anterior or isthmic border, which is also the shortest, corresponds to the
junction of the two alæ in the median line in front; very prominent above, where
it forms the pomum Adami, it becomes depressed before again projecting less markedly
below. Posteriorly, at the angle of junction it gives attachment to the stalk of the
epiglottis, the true and false vocal cords, the thyro-arytenoid and thyro-epiglottidei
muscles.
The superior border, which gives attachment to the thyro-hyoid membrane, is

940
THE ORGANS OF VOICE
sinuous. Slightly depressed posteriorly, it rises in front, and then becomes abruptly
scooped out and everted to form the side of the great median notch.
The inferior border is somewhat sinuous. It gives attachment in front to the
middle portion of the crico-thyroid membrane, and behind to the crico-thyroid muscle,
and presents the small tubercle already noticed at the termination of the oblique
line.
The posterior border, thick and rounded, projects above and below into the
superior and inferior cornua, and gives partial insertion to the stylo- and palato-
pharyngei muscles.
The superior cornua project inwards as well as upwards and backwards. To
their tips are attached the thyro-hyoid ligaments, and near each root appears the
tubercle at the upper end of the oblique line.
FIG. 524.-SIDE VIEW OF THE CARTILAGES OF THE LARYNX. (Modified from
Bourgery and Jacob.)
HYOID BONE-
Thyro-hyoid membrane-
SUPERIOR BORDER OF THYROID
THYROID
CARTILAGE
Crico-thyroid muscle.
Crico-thyroid membrane
(median portion)
CRICOID
CARTILAGE
Crico-thyroid muscl
THIRD RING OF TRACHEA
-Thyro-hyoid ligament
CARTILAGO TRITICEA
SUPERIOR CORNU
Superior tubercle
-Stylo-pharyngeus and
palato-pharyngeus
Thyro-hyoid muscle
-SURFACE OF ALA OVERLAPPED BY
INFERIOR CONSTRICTOR
Sterno-thyroid muscle and
inferior tubercle
-Inferior constrictor
The inferior cornua are short, blunt processes. They project inwards as well
as downwards and forwards. By means of a small oval concave facet (directed
downwards as well as inwards) placed on their inner faces, the inferior cornua
articulate with the facets on the sides of the cricoid cartilage. They give partial
attachment to the inferior constrictors of the pharynx and crico-thyroid muscles in
addition to the ligaments of the joint.
The CRICOID CARTILAGE is thick and strong, and forms a complete ring around the
lower part of the larynx. Behind, it presents a quadrate surface, but narrows rapidly
in its anterior half to only one-fourth or one-fifth of its posterior depth. Hence its
comparison to a signet ring. It thus possesses an anterior and a posterior portion,
and a superior and inferior border, and presents four articular surfaces.
The posterior quadrate portion is divided by a median vertical ridge which
RIST THE LARYNX
941
separates two broad and shallow depressions. To this ridge some of the longitudinal
fibres of the œsophagus are attached, and the depressions give origin to the
posterior crico-arytenoid muscles.
The anterior portion is narrow and rounded, and gives attachment in front to
the crico-thyroid muscles, and more posteriorly to some fibres of the inferior
constrictor of the pharynx.
Between these two halves of the ring, but nearer the lower border, is placed the
oval surface (looking upwards and outwards) for articulation with the inferior cornu
of the thyroid cartilage.
The inner surface is smooth and lined by mucous membrane.
The superior border bounds the quadrate plate above, and then passes obliquely
downwards and forwards. An oval, convex, obliquely placed articular surface, upon
which moves the arytenoid cartilage, separates these two portions of the upper
border.
The oblique half gives attachment to the crico-thyroid membrane, and, laterally
and external to this, to the lateral crico-arytenoid muscle.
The inferior border-horizontal, and often deeply notched at the sides-is
attached to the first ring of the trachea by fibrous membrane.
The arytenoid cartilages are irregular, three-sided pyramids, which articulate
by their bases with the oblique facets on the superior border of the cricoid cartilage,
and support upon their apices the cornicula laryngis.
The space between them in certain animals has been likened to the mouth of a
pitcher, and hence their name. Each cartilage presents three surfaces, divided by
three borders, with a base, apex, and angles.
The surfaces. The posterior is concave, smooth, and gives attachment to the
arytenoid muscle.
The anterior is irregular and convex. It gives attachment by a small tubercle
to the false vocal cord, and also to the thyro-arytenoid muscle.
The internal is almost flat, smooth, and narrow, and covered by mucous
membrane.
The base is obliquely hollowed, and presents internally the facet for articulation
with the cricoid cartilage.
The angles.-The anterior is prolonged for the attachment of the true vocal
cord. It is known as the vocal process, and with the aid of the laryngoscope is
easily seen during life.
The external or muscular is thick and blunt, and gives attachment in front to
the lateral crico-arytenoid, and behind to the posterior crico-arytenoid muscle.
The internal is unimportant; it is tied to the corresponding cartilage and
to the cricoid by a fibrous band which is known as the transverse or crico-
arytenoid ligament.
The borders.--The two internal, which limit the narrow inner face, are nearly
parallel and almost vertical; whilst the external slopes upwards, inwards, and
backwards.
The apex projects inwards and backwards, and supports the corniculum. The
cartilage here becomes fibrous in structure.
The EPIGLOTTIS is a median leaf-like plate of yellow elastic cartilage attached by
a stalk inferiorly to the retiring angle of the thyroid cartilage below the median
notch. When denuded of its mucous covering, it is seen to be pitted with numerous
depressions for the lodgment of glands (fig. 530).
Placed with its lingual surface above, and its stalk in front, it has been
compared to an elongated saddle. It varies very considerably both in shape and
inclination, its leaf-like portion being sometimes considerably curled upon itself.
It is placed nearly vertically in the adult, but in children is frequently so much.
depressed that its posterior free surface is inclined below its anterior. Hence its



942
THE ORGANS OF VOICE
variable appearance when examined in the living subject with the laryngoscope.
It is somewhat depressed and folded upon itself during deglutition.
Its anterior or lingual aspect is free above and covered with mucous membrane,
which lower down is reflected forward upon the base of the tongue in three folds-
one median (which encloses elastic tissue) and two lateral-the glosso-epiglottidean
folds. Beneath the mucous membrane the deeper attached portion of this surface
is tied to the hyoid bone by a median elastic membrane, named hyo-epiglottidean
ligament. A quantity of elastic and fatty tissue, closely blended with this ligament
FIG. 525.-FRONT VIEW OF THE CRICOID AND ARYTENOID CARTILAGES. (Modified
from Bourgery and Jacob.)
Thyro-arytenoideus muscle
Insertion of crico-thyroid muscle-
ANTERIOR SURFACE OF ARYTENOID CARTILAGE
Cut edge of capsular ligament
-Lateral crico-arytenoid muscle
MUSCULAR EXTERNAL ANGLE OF ARYTENOID
CARTILAGE
Lateral crico-arytenoid muscle
CRICOID CARTILAGE
above, connects the epiglottis to the thyro-hyoid membrane in front. This is known
as the periglottis (fig. 528). Still lower, the fibro-elastic tissue which forms the
thyro-epiglottidean ligament attaches the stalk to the thyroid cartilage.
The posterior or laryngeal surface, concavo-convex from above downwards, and
concave from side to side, is free and covered with mucous membrane for its whole
extent. About its centre it projects backwards to form the cushion of the
epiglottis.
The lateral margins, which are free above, give attachment below to the aryteno-
FIG. 526.-BACK VIEW OF THE CRICOID AND ARYTENOID CARTILAGES. (Modified
from Bourgery and Jacob.)
POSTERIOR SURFACE OF ARYTENOID
MUSCULAR EXTERNAL ANGLE
Crico-arytenoid joint
MEDIAN RIDGE.
POSTERIOR SURFACE OF CRICOID.
CARTILAGE
Longitudinal fibres of oesophagus
CORNICULUM LARYNGIS
Arytenoideus muscle
Crico-arytenoideus posticus muscle
Crico-arytenoideus posticus muscle
-ARTICULAR SURFACE FOR INFERIOR CORNU
OF THYROID CARTILAGE
epiglottidean folds of mucous membrane which form the boundaries of the superior
aperture of the glottis, and also on each side to a fold of the membrane, containing
fibrous tissue, which runs upwards to the posterior pillar of the fauces-the
pharyngo-epiglottidean fold.
The CORNICULA LARYNGIS, or cartilages of Santorini, are the two little cone-
shaped yellow elastic cartilages which project backwards and inwards from the
summits of the arytenoids, with which they are sometimes directly continuous. A
joint, however, is usually present.
THE LARYNX
943
The CUNEIFORM CARTILAGES, or cartilages of Wrisberg, are placed within
the aryteno-epiglottidean folds. These small conical and elongated yellow elastic
cartilages produce the thickenings just mentioned in front of the cornicula.
Calcification. The hyaline cartilages of the larynx are especially prone to calcify
after middle life, but the yellow elastic cartilages take no share in the process.
The little cartilago triticea, however, is frequently converted into bone.
In the thyroid cartilage the deposit of bony salts usually commences near the
posterior border and in the cornua, extending forwards into the lower part of the
ala, and finally upwards, until in advanced cases the whole cartilage is involved.
In the cricoid cartilage the calcification commences above on each side in the
neighbourhood of the crico-arytenoid joints, and extends downwards, and finally
both forwards and backwards.
In the arytenoid the calcification commences in the base, but it finally involves
the whole cartilage with the exception of the summit, where the hyaline structure (as
already noted) disappears.
The ligaments (extrinsic).-The thyro-hyoid membrane is composed mainly
of elastic fibres. It is attached below to the upper margin of the thyroid cartilage,
and above to the upper and hinder margin of the hyoid bone. It presents a thick
FIG. 527.-SUPERIOR VIEW OF THE CARTILAGES OF THE LARYNX.

ANTERIOR SURFACE OF
CRICOID CARTILAGE
True vocal chord
Crico-thyroid.
membrane
CRICOID CARTILAGE
VOCAL PROCESS-
ANTERIOR SURFACE OF
ARYTENOID CARTILAGE
INFERIOR CORNU OF-
THYROID CARTILAGE
SUPERIOR CORNU OF.
THYROID CARTILAGE
POSTERIOR SURFACE OF
ARYTENOID CARTILAGE
Anterior portion of
crico-thyroid membrane
Cut edge of
crico-thyroid membrane
-SUPERIOR BORDER OF
THYROID CARTILAGE
-CRICO-THYROID
ARTICULATION
-SUPERIOR BORDER OF
CRICOID CARTILAGE
CORNICULUM LARYNGIS
-POSTERIOR SURFACE OF
CRICOID CARTILAGE
central portion (stretching between the median notch and the body of the hyoid bone),
and thinner lateral portions, looser in texture, which are pierced by the superior
laryngeal nerves and arteries. Posteriorly, the membrane is loosely connected with
the superior cornua of the thyroid cartilage, and above these it is bounded on each
side by thickened bands, the thyro-hyoid ligaments, which pass between their tips
and the greater cornua of the hyoid bone.
A little grain-like cartilage (cartilago triticea) is usually imbedded in this band
just above the thyroid cornu.
The central portion of the membrane is mainly subcutaneous, a bursa inter-
vening where it is overhung by the body of the hyoid bone.
Its lateral portions are covered by the thyro-hyoid muscles. Posteriorly it is
separated from the epiglottis by the mucous membrane at the base of the tongue
and the areolar fatty tissue already described.
The crico-thyroid membrane (intrinsic) is composed chiefly of elastic tissue.
It presents a prominent rounded median portion overlapped slightly by the crico-
thyroid muscles, but between these muscles it is subcutaneous. It is crossed by a
small anastomotic arch formed by the crico-thyroid twigs of the superior laryngeal
artery; one or two small holes transmit vessels from the arch to the interior of the
larynx.

944
THE ORGANS OF VOICE
This median portion of the membrane stretches between the borders of the two
cartilages. The lateral and thinner portions pass upwards from the inner border
of the upper margin of the cricoid cartilage in contact with the laryngeal mucous
membrane, and within the embrace of the thyroid cartilage, to form the true vocal
cords or inferior thyro-arytenoid ligaments. These elastic bands extend from the
vocal processes of the arytenoid cartilages to the retiring angle of the thyroid near
its centre.
The lateral portions of this membrane are covered superficially by the thyro-
arytenoid and lateral crico-arytenoid muscles.
The superior thyro-arytenoid ligaments are contained within the arched folds
of mucous membrane which form the false vocal cords. They consist of a few
bundles of fibrous tissue.
FIG. 528.-SIDE VIEW OF THE MUSCLES AND LIGAMENTS OF THE LARYNX.

Epiglottis-
Cut edge of hyo-epiglottidean.
ligament
SECTION THROUGH BODY OF HYOID
BONE
Periglottis
Cut edge of thyro-hyoid
membrane
Thyro-epiglottideus muscle
Aryteno-epiglottidean fold
Aryteno-epiglottideus muscle
SECTION OF THYROID CARTILAGE
Thyro-arytenoideus muscle
Crico-arytenoideus lateralis
muscle (the pointer crosses
erico-thyroid membrane)
CRICOID CARTILAGE
Arytenoideus muscle
-Crico-arytenoideus posticus
good
-Recurrent laryngeal nerve
The crico-arytenoid or transverse ligament has been already sufficiently
noticed.
The Joints of the Larynx.-The crico-thyroid joints are lined by a synovial
membrane, embraced by a thin capsule of radiating fibres, and often strengthened
posteriorly by a well-marked fibrous band. They permit of movement between the
two cartilages upon an axis passing transversely through both joints, and a limited
gliding of the cricoid upwards and backwards. As can be shown on the living
body, the cricoid is the cartilage which swings between the inferior thyroid cornua.
The crico-arytenoid joints possess a synovial membrane enveloped in a thin and
moderately loose capsule, strengthened posteriorly by a band passing between the
cricoid and the inner and back part of the arytenoid--the posterior crico-arytenoid
ligament; and internally by the interarytenoid band, which is occasionally liga-
mentous-the crico-arytenoid ligament.

201 THE LARYNX
945
The cricoid articular surface is oval, convex, and oblique, with its long axis
passing from behind, forwards, and outwards. The opposed articular surface on
the base of the arytenoid is also oval, but it is concave with its long axis passing
from before backwards.
It follows that the two surfaces never completely cover each other at any one
time. The arytenoid rotates on a vertical axis near to and parallel with its inner
surface, and it also glides forwards and inwards, or in an opposite direction.
These movements are associated-the gliding forwards and inwards with the inward
rotation, and the gliding outwards and backwards with the outward rotation.
The Muscles. The muscles are divisible into an extrinsic group, passing between
the larynx and parts beyond; and an intrinsic group, belonging entirely to the
organ itself.
The extrinsic muscles are the sterno-thyroid, thyro-hyoid, stylo- and palato-
pharyngei, and the inferior constrictors of the pharynx. It should be noted that the
muscles which fix the hyoid bone, and also those which close the lower jaw, assist
the action of the above mentioned.
The intrinsic muscles.-The crico-thyroid is attached below to the front and
side of the cricoid cartilage, and above to the lower border of the thyroid cartilage.
The lower fibres, which are horizontal and often distinct, pass to the front border
of its inferior cornu, and act by pulling the cricoid directly backwards, whilst the
FIG. 529.-SCHEME OF RIMA, SHOWING ACTION OF CRICO-ARYTENOIDEUS POSTICUS, WHICH
DRAWS THE ARYTENOID CARTILAGE FROM I TO II. (Modified from Stirling.)
II
I
II
I
spreading fibres which form the rest of the muscle swing the cricoid between the
crico-thyroid joints, pulling it upwards as well as backwards. Both portions of the
muscle make tense the vocal cords, and are supplied by the external laryngeal
nerve. It is overlapped laterally by the sterno-thyroid, having beneath it a small
portion of the crico-thyroid membrane and some of the lower fibres of the
lateral crico-arytenoid muscle. The central portion of the crico-thyroid membrane
appears in the angular interval between the two muscles.
The crico-arytenoideus posticus arises from the quadrate surface situated on
each side of the posterior median ridge of the cricoid cartilage. Its fibres rapidly
converge to be inserted into the posterior portion of the outer angle (muscular
process) of the arytenoid cartilage.
The upper fibres are chiefly concerned in rotation of the arytenoid cartilage,
whilst the lower produce its gliding movement. It is a dilator of the rima glottidis.
Some of the lowest fibres occasionally pass to the inferior cornu of the thyroid
cartilage, and are known as the kerato-cricoideus or kerato-thyroideus.
It is covered posteriorly by mucous membrane, and is supplied by the recurrent
laryngeal nerve. A few of the longitudinal fibres of the oesophagus arise from
the ridge which separates the two muscles.
The crico-arytenoideus lateralis arises from the upper border of the cricoid
3 P

946
THE ORGANS OF VOICE
cartilage between the origin of the crico-thyroid and the crico-arytenoid articulation.
It narrows to be inserted into the fore part of the muscular process of the arytenoid
cartilage. It draws the cartilage forwards, relaxing and slightly approximating the
cords.
It is overlapped by the thyroid cartilage, and anteriorly by the crico-thyroid
muscle; internally it is covered by mucous membrane. The upper portion is con-
FIG. 530.-POSTERIOR VIEW OF THYROID CARTILAGE WITH EPIGLOTTIS.
GREATER CORNU OF HYOID
BONE
BODY OF HYOID BONE-
Thyro-hyoid ligament-
EPIGLOTTIS
Median notch-
Origin of thyro-epiglottic.
ligament
POSTERIOR EDGE OF THYROID.
CARTILAGE
Origin of thyro-aryte-
noideus muscle
INFERIOR CORNU-
SMALLER CORNU OF HYOID
BONE
CARTILAGO TRITICEA
SUPERIOR CORNU OF THYROID
CARTILAGE
RIGHT ALA OF THYROID
CARTILAGE
False vocal cord
True vocal cord
Origin of thyro-epiglot-
tideus muscle
tiguous to the thyro-arytenoid, with which it is occasionally blended. It is supplied
by the recurrent laryngeal nerve.
The thyro-arytenoid muscle, which is placed above the foregoing, arises broadly
from the lower two-thirds of the inner surface of the thyroid cartilage close to its
retiring angle, and slightly from the posterior surface of the crico-thyroid membrane.
Narrowing as it passes outwards and backwards, it is inserted into the anterior
FIG. 531.--SCHEME SHOWING ACTION OF THYRO-ARYTENOID DRAWING THE VOCAL CORDS
AND VOCAL PROCESSES FROM II To I. (Modified from Stirling.)
Π
I
IN
surface of the arytenoid cartilage, and also into its base close to the attachment of
the lateral crico-arytenoid muscle. Some few of its fibres pass onwards and become
continuous with the oblique fibres of the arytenoid muscle.
The lower portion of the muscle lies parallel to and blends with the outer
surface of the vocal cord. The upper and thinner portion is placed immediately
beneath the mucous membrane, and overlies the ventricle and laryngeal pouch.

THE LARYNX
947
These muscles by rotating the arytenoid cartilages draw the vocal processes
downwards and inwards, and thus approximate the vocal cords. By pulling
forward the cartilages, they relax the cord as a whole. According to some
authorities, the fibres attached to the outer border of the vocal cord act upon it by
modifying its elasticity, tightening a portion in front and relaxing the remainder, in
this somewhat resembling the stop action of the finger on a violin string.
The arytenoideus consists of transverse fibres passing from one arytenoid
cartilage to the other, and attached to their posterior concave surfaces. Super-
ficially are some oblique fibres, which decussate where they meet. These pass from
the outer angle of one cartilage below to the summit of the opposite, A few of
these fibres pass onwards to the aryteno-epiglottidean fold and side of epiglottis.
These, reinforced by fibres attached to the summit of the arytenoid cartilage,
constitute the aryteno-epiglottideus muscle. A few fibres blend with the thyro-
arytenoid muscle.
The arytenoideus approximates and depresses the arytenoid cartilages. These
actions are assisted by the aryteno-epiglottidei, which depress the epiglottis and
contract the superior aperture of the larynx.
The thyro-epiglottideus (sometimes described as part of the thyro-arytenoid)
consists of fibres attached below to the thyroid cartilage which, spreading above,
FIG. 532.-SCHEME SHOWING ACTION OF ARYTENOIDEUS DRAWING ARYTENOID
CARTILAGE FROM NEUTRAL POSITION I TO II. (Modified from Stirling.)
بر
II
II
reach the aryteno-epiglottidean fold, and the outer wall of the laryngeal pouch as
well as the epiglottis. (For the nerve-supply of the laryngeal muscles see page 950.)
The Interior of the Larynx.-The superior aperture, or opening of the glottis,
is triangular in shape, wide in front, narrow behind, and placed so obliquely as to
be almost vertical in the living subject. Above and in front it is bounded by the
epiglottis, behind and below by the interarytenoid notch, whilst on each side
stretches the aryteno-epiglottidean fold containing muscular and ligamentous
fibres. This fold presents two thickened areas, one at the summit of the arytenoid
cartilage, and one just in front and above this, formed by the bulging of the
cornicular and cuneiform cartilages respectively.
Bounded internally by this fold, and externally by the wing of the thyroid
cartilage, is a shallow depression-the sinus pyriformis.
The cavity of the larynx extends from the aperture above described to the lower
border of the cricoid cartilage.
Its lining of mucous membrane varies much in its colour and thickness and its
fixity to the structures which it overlies. On the surface of the true vocal cords it is
extremely thin, pale and adherent, whilst above and below this it is more vascular
and more loosely attached to the underlying parts. The submucous tissue contains
numerous elastic fibres and mucous glands.
3 P2
948
THE ORGANS OF VOICE
The cavity is naturally divided into two portions-supra- and infra-rimal-
divided by the glottis or interval between the two true vocal cords.
The suprarimal portion corresponds to the space between the wings of the
thyroid cartilage. It is broad and triangular above, but narrower below, and its
walls are much deeper in front than behind. Immediately above each vocal cord
is an oblong depression-the ventricle-bounded above by the crescent-shaped
FIG. 533.-VIEW OF INTERIOR OF LARYNX AS SEEN DURING INSPIRATION.

Vallecula
Cushion of epiglottis
BASE OF TONGUE
Median glosso-epiglottidean
-EPIGLOTTIS
fold
True vocal cord-
Rima glottidis
Sinus pyriformis-
Arytenoid commissure.
Fossa innominata
-Aryteno-epiglottidean fold
CARTILAGE OF WRISBERG
CARTILAGE OF SANTORINI
Pharynx
edge of the false vocal cord, below by the straight margin of the true vocal cord,
and externally by the thyro-arytenoid muscle. The ventricle extends nearly the
whole length of the vocal cords, and is lined by a thin and tightly adherent mucous
membrane. It allows the free vibration of the true vocal cords in the production
of sound. From the anterior part of the ventricle there extends upwards, for about
FIG. 534.-VIEW OF INTERIOR OF LARYNX AS SEEN DURING VOCALISATION.

BASE OF TONGUE
Median glosso-epiglottidean
fold
Fossa innominata
True vocal cord.
Sinus pyriformis
PROCESSUS VOCALIS
EPIGLOTTIS
-Cushion of epiglottis
-Ventricle
Aryteno-epiglottidean fold
CARTILACE OF WRISBERG
CARTILAGE OF SANTORINI
Arytenoid commissure
Mored odt to Pharynx
wol ad.
half an inch, a small blind sac, named the laryngeal pouch. This reaches as high
as the upper border of the thyroid cartilage; its mouth below is narrow and guarded
by two little folds of mucous membrane. A delicate fibrous investment is continued
from the true vocal cord around the sac. Some fatty tissue is enclosed within this,
and its mucous lining contains numerous glands. On its outer side are some
fibres of the thyro-arytenoid muscle; whilst on its inner side is a thin layer of

MOTO THE LARYNX
949
muscular fibres, derived from the aryteno-epiglottideus, and sometimes known as
Hilton's muscle, or the compressor sacculi laryngis.
The superior or false vocal cords stand farther apart than the true, and cannot
be made absolutely tense. They have already been sufficiently described. A
shallow fossa-the fossa innominata is observable, especially during phonation,
between the false cord and the aryteno-epiglottidean fold; it is placed a little behind
the epiglottis.
The inferior or true vocal cords are the structures concerned in the production
of the voice. They stretch from the vocal process of the arytenoid cartilage to the
thyroid cartilage, their tension and position varying under muscular action. The
cords are pearly white in appearance, and present flattened surfaces where they face
FIG. 535.-NERVES OF THE LARYNX. (Posterior view.)

FORAMEN CÆCUM
-BASE OF TONGUE
EPIGLOTTIS
GREATER CORNU OF-
HYOID BONE
CARTILAGO TRITICEA
SUPERIOR CORNU OF-
THYROID CARTILAGE
EXTERNAL LARYN-
GEAL NERVE
SUPERIOR LARYN-
GEAL NERVE
Cut edge of thyro-
hyoid membrane
BRANCH TO LATERAL
CRICO ARYTENOID
AND THYRO-ARYTE-
NOID MUSCLES
BRANCH JOINING-
THE
SUPERIOR
LARYNGEAL NERVE
Crico arytenoideus
posticus muscle
INFERIOR CORNU OF
THYROID CARTILAGE
Arytenoideus muscle
RECURRENT
LARYNGEAL
NERVE
each other internally, with a free sharp edge above. It is this edge which is thrown
into vibrations during phonation. They are about seven lines (14 mm.) in length
in the adult male.
The rima glottidis is the chink bounded on each side by the vocal cords and
the inner surfaces of the arytenoid cartilages with their vocal processes.
It is limited behind by the interarytenoid fold, and presents the appearance of
an elongated triangle, measuring, in the adult male, nearly an inch in length, and
three or four lines across at its widest part.
When observed during life, the rima glottidis is seen to vary very considerably.
On inspiration the vocal cords, whilst almost touching in front, are separated
behind from a quarter to half an inch (6 to 12 mm.), forming an angle directed
950
THE ORGANS OF VOICE
outwards, where they terminate in the vocal processes, the glottis presenting a
lozenge-shaped appearance.
On phonation the cords become parallel and closely approximated, and the
vocal processes approaching each other cause the angle to be turned inwards.
The infrarimal portion of the larynx rapidly widens out into a nearly circular
cavity at the lower border of the cricoid cartilage, from which point it is continuous
with the lumen of the trachea.
Nerves. The nerves of the larynx are derived from the superior and inferior
(recurrent) laryngeal branches of the vagus.
The superior laryngeal. The sensory nerve of the larynx gives off near its
origin behind the carotid sheath a long and slender filament, which is principally
motor. This (external) branch is distributed to the crico-thyroid muscle, a few
minute filaments reaching the mucous membrane of the larynx.
Its larger and main branch (internal) is sensory, and passes through the
aperture in the thyro-hyoid membrane above the superior laryngeal artery. It
divides beneath the mucous membrane which lines the sinus pyriformis, distributing
branches upwards to supply both surfaces of the epiglottis and the base of the
tongue immediately in front; inwards to the aryteno-epiglottidean fold and its
neighbourhood; whilst others pass downwards to the mucous membrane of the
deeper portions of the larynx as far as the true vocal cords.
The inferior (recurrent) laryngeal, the motor nerve of the larynx, ascends in
the groove between the trachea and oesophagus, both of which structures it supplies.
It reaches the larynx below the edge of the inferior constrictor, and immediately
behind the crico-thyroid joint. At this spot it divides into two branches: an
anterior to supply the thyro-arytenoideus, crico-arytenoideus lateralis, with the
muscles of the epiglottis; and a posterior branch to the crico-arytenoideus posticus
and arytenoideus.
The superior laryngeal communicates with this branch by a slender filament,
which passes downwards near to the posterior border of the thyroid cartilage.
This communication sometimes takes place beneath the posterior crico-arytenoid
muscle.
The arteries are derived from the superior and inferior thyroid, the epiglottis
receiving some twigs from the dorsalis linguæ of the lingual.
The veins correspond with the arteries; and the lymphatics, which are scanty,
follow the vessels and end in the deep cervical glands.
THE TRACHEA

The trachea, or air-tube, which is cylindrical in shape, but flattened posteriorly,
extends from the lower border of the fifth cervical vertebra to the fourth or fifth
thoracic vertebra. It is continuous with the larynx above, and divides into the two
bronchi below. It measures from four and a half to five inches in length, and is
nearly an inch in width.
Relations. In its cervical portion it rests upon the oesophagus, which curves
somewhat to the left at the root of the neck; on each side, but especially on the
left, it comes into relationship with the lateral lobes of the thyroid gland, the
inferior thyroid arteries, and the recurrent laryngeal nerves. These latter running
upwards gain the lateral groove between the trachea and oesophagus; and lastly,
it is in relation with the sheath containing the common carotid artery, internal
jugular vein, and pneumogastric nerve.
HOT THE TRACHEA
951
In front it is crossed by the thyroid isthmus, and in addition to the skin and
superficial fascia are the following structures :-The anterior jugular veins, and
commonly at the root of the neck a communicating branch passing transversely
between them, the inferior thyroid veins, and when present the thyroidea ima, and
the thymus gland or its remains. It is overlapped on each side by the sterno-hyoid
and sterno-thyroid muscles, with a narrow interval between them, across which
passes a strong deeper layer of the cervical fascia and a thinner superficial layer.
In its thoracic portion the trachea still rests upon and retains its connection with
the œsophagus, which separates it from the spine. It lies between the two pleural
sacs and pneumogastric nerves, having in front of it the sternum with the origins
of the sterno-hyoid and thyroid muscles, the thymus gland, the deep cardiac plexus,
and also the transverse portion of the arch of the aorta, which vessel crosses the
tube just above its bifurcation; the innominate artery passes upwards to its right,
FIG. 536,-ANTERIOR VIEW OF THE LARYNX, WITH THE TRACHEA AND BRONCHI.
(Modified from Bourgery.)

FIRST RING OF TRACHEA-
POSITION OF THYROID ISTHMUS
LEVEL OF STERNUM
Arch of aorta
LAST RING OF TRACHEA
Right pulmonary artery.
Left pulmonary
artery
LEFT BRONCHUS
and the left carotid ascends to reach its left side with the left recurrent laryngeal
The left innominate vein crosses the roots of these vessels.
nerve.
Structure. The trachea is made up of a series of imperfect cartilaginous rings,
deficient behind, connected throughout by fibro-elastic membrane, with muscular
fibres, the trachealis muscle, a special layer of yellow elastic fibres, and a lining of
mucous membrane.
The cartilaginous rings vary in number from sixteen to twenty. They are
incomplete, being deficient in the hinder third, and are connected in a continuous
series by a fibrous membrane, which divides to enclose them, but reunites in the
narrow intervals between. It forms a definite layer where the cartilages are wanting,
so that it may be regarded as complete throughout the tube. The inside of the
trachea is ridged transversely by the rings, which are rounded on their inner
952
THE ORGANS OF VOICE
surfaces;
but it is comparatively smooth externally, where the outer surfaces of the
rings are flattened.
The first cartilage is broad, and is occasionally united with the cricoid above,
or second ring of the trachea below.
The last cartilage is likewise broad and strong, and sends a curved beak down-
wards and backwards at the point of bifurcation of the trachea. It forms an
imperfect ring on each side above the commencement of the corresponding
bronchus.
Two cartilages not uncommonly unite in part, and thus present a bifurcated
appearance.
The fibres of the trachealis are unstriped, and form a transverse layer at the
posterior flattened part of the tube, with an indistinct layer of longitudinal fibres
superimposed.
The yellow elastic fibres, which exist throughout the entire mucous membrane,
form a definite and deep layer at the posterior flattened portion of the tube. They
are gathered into strong longitudinal flattened bands, especially well seen at the
lower part of the trachea, and where the fibres separate to pass into the bronchi.
The mucous membrane is smooth and pinkish in colour; it is provided with
numerous glands, especially at its hinder part, and is lined by a columnar ciliated
epithelium.
The arteries are derived from the inferior thyroid.
The veins join the thyroid plexuses; and the nerves are supplied by branches
from the pneumogastric, the recurrent laryngeal, and sympathetic.
THE BRONCHI
The right bronchus (fig. 536) is about one inch in length. It is shorter and wider
than the left, and in direction more horizontal in its passage to the root of the lung.
Relations. The vena azygos major arches above it from behind to end in the
superior vena cava, which latter is placed anteriorly. The right pulmonary artery
is at first below, and then in front of it.
The left bronchus is about two inches in length; it is more oblique, longer, and
narrower than the right.
Relations. It lies beneath the arch of the aorta, and rests upon the oesophagus,
thoracic duct, and finally the descending aorta. The left pulmonary artery lies
above and then in front of it. On looking down the trachea the dividing ridge
between the two bronchial orifices is seen to be on the left of the middle line,
more of the right orifice for this reason being visible. This explains the fact that
foreign bodies entering the trachea most commonly become lodged in the right
bronchus.
At the root of the lung the right bronchus distributes a branch to the upper
lobe of the lung which reaches above the level of the pulmonary artery. The
remaining stem passes behind the pulmonary artery, and divides into two branches
for the middle and lower lobes respectively. These, after several subdivisions,
becomes bronchioles.
The left bronchus lies below the pulmonary artery, and divides into two
branches-one for each of its lobes-these corresponding with those which supply
the middle and lower lobes of the right lung.


THE THYROID BODY OR GLAND
The thyroid body is of a reddish colour, and is classed amongst the ductless
glands. It consists of two lateral lobes, and a connecting isthmus which unites
them below.
SO THYROID GLAND
953
The lateral lobes pass upwards on each side nearly as high as the oblique line
which crosses the ala of the thyroid cartilage, and extend below as far as the fifth
or sixth ring of the trachea. The isthmus, which varies in breadth a good deal in
different subjects (from a quarter to three-quarters of an inch), usually covers the
second and third rings, but sometimes descends over the fourth ring of the trachea.
The gland is convex and rounded on its outer surface, but deeply it is moulded
to the parts which it overlies. It commonly weighs from one to two ounces, but is
larger in the female, and is often increased in size during menstruation.
The lateral lobes are pyriform in shape, with their broad ends below, and
SMALLER CORNU OF HYOID-
BONE
FIG. 537.--VIEW OF THYROID BODY.

Thyro-hyoid ligament-
THYROID CARTILAGE
BODY OF HYOID BONE
-Thyro-hyoid membrane
Thyro-hyoid muscle
-Inferior constrictor
-Sterno-thyroid mus le
Median portion of crico-
thyroid membrane
-Crico-thyroid muscle
LATERAL LOBE OF THYROID
BODY
THYROID ISTHMUS-
TRACHEA-
SECTION THROUGH
CARTILAGES
measure about two inches in length, three-quarters of an inch in breadth, and
about an inch in thickness near the middle.
Relations. The thyroid body is covered by the sterno-hyoid, sterno-thyroid,
and omo-hyoid muscles, and is slightly overlapped by the anterior border of the
sterno-mastoid muscle. The upper extremity of the lateral lobe lies between the
sterno-thyroid and inferior constrictor of the pharynx, which latter separates it from
the hinder part of the ala of the thyroid cartilage and its inferior cornu. Its
posterior rounded border reaches backwards as far as the pharynx, and comes into
954
THE ORGANS OF VOICE
relationship, more especially on the left side, with the oesophagus and recurrent
laryngeal nerve, with branches of the inferior thyroid artery, and with the sheath
containing the great vessels of the neck.
The middle or pyramidal process is developed in connection with the thyro-
glossal duct, and, like the isthmus, which has a similar origin, it is the most
variable portion of the gland.
When present it is connected inferiorly with the isthmus or neighbouring part
of the left lateral lobe. It extends upwards to be connected by means of fibrous
tissue with the thyro-hyoid membrane or the body of the hyoid bone.
It varies very much in appearance, but its apex is usually above. In some cases
it is divided, and occasionally it is represented throughout by fibrous tissue.
The thyro-glossal duct may, even in the adult, remain more or less pervious in
its lower portion. Above, it is represented by the foramen cæcum on the dorsum
of the tongue.

FIG. 538.-THYROID BODY, WITH MIDDLE LOBE AND LEVATOR MUSCLE.
Stylo-hyoid ligament"
-EPIGLOTTIS
-BODY OF HYOID BONE
Thyro-hyoid ligament
Thyro-hyoid membrane
Sterno-hyoid muscle-
Omo-hyoid
Thyro-hyoid-
-Levator glandulæ thyroidea
THYROID CARTILAGE
Crico-thyroid-
Sterno-thyroid-
-PYRAMIDAL PROCESS OF THYROID BODY
ISTHMUS
-LEFT LATERAL LOBE
TRACHEA
A frequent muscular slip, derived from the thyro-hyoid (levator glandulæ
thyroidea), descends from the hyoid bone to the isthmus.
The suspensory ligaments of the thyroid gland, two broadish bands, pass from
the inner and back part of the lateral lobes upwards to the sides of the cricoid
cartilage. Below, they are intimately blended with the investing capsule, and thus
form on each side a sling which suspends the organ. These ligaments have no
sharply defined edges, being continued into the layers of fasciæ covering the front
of the cricoid cartilage and posterior surface of the trachea. The recurrent laryngeal
nerve lies in immediate contact with the outer surface of the ligament at its upper
attachment. (Berry.)
Structure. The thyroid body, enveloped in a dense but thin covering of
THYROID GLAND
955
areolar tissue, is made up of a number of closed follicles. These are surrounded
by an open vascular meshwork supported by the interstitial connective tissue. The
follicles are grouped into irregular lobules, and these form in turn the lobes of the
gland. Both the interior of the follicles and the spaces in the connecting areolar
tissue may become filled with colloid material.
Vessels. The arteries-which are relatively very large and frequently ana-
stomose are the two superior thyroids, the two inferior thyroids, and an occasional
branch which ascends on the front of the trachea, the thyroidea ima. This latter
is derived either from the innominate artery or from the arch of the aorta.
The superior thyroid arteries descend to supply the apices and inner and
fore parts of the lateral lobes; whilst the inferior ascend to supply their outer and
hinder portions below.
The veins are the superior middle and the inferior thyroid. The two former
FIG. 539.-THE SUSPENSORY LIGAMENTS OF THE THYROID BODY. (After Berry.)

Crico-arytenoideus posticus
LATERAL BONE OF THYROID GLAND
Suspensory ligament of the left
side
RECURRENT LARYNGEAL
NERVE
join the internal jugular vein, and the latter the innominate of the corresponding
side.
The nerves are derived from the inferior and middle cervical ganglia of the
sympathetic.
THE THYMUS BODY OR GLAND
The thymus body, like the thyroid, is ductless. It reaches its highest de-
velopment about the end of the second year. Although it occasionally retains
a considerable size in the adult, it usually disappears or shrivels away to an
insignificant vestige.
It is commonly made up of two elongated, nearly equal pyramidal lobes of a
greyish pink colour, which meet one another near the middle line; but they vary
in number and are inconstant in size. There may be but a single lobe present,
or a third may intervene between the other two. Sometimes the right lobe and
sometimes the left lobe is the larger.
The thymus body is about two inches in length, about one inch and a half in
breadth at its base, and a quarter of an inch in thickness.
956
THE ORGANS OF VOICE
Its weight at birth is about half an ounce.
Relations. The thyroid body at the period of its fullest development lies partly
in the thorax and partly in the neck. It extends upwards as far as the thyroid
body covered by the sterno-hyoid and thyroid muscles, completely hiding the trachea.
Below, it descends into the superior mediastinum between the pleural sacs and
internal mammary vessels as far as the fourth rib cartilages, and lies behind the
sternum and in front of the pericardium and larger vessels.
FIG. 540.-THYMUS GLAND IN A CHILD AT BIRTH.

HYOID BONE
Thyro-hyoid
membrane
THYROID CARTILAGE
Thyro-hyoid
muscle
Lateral portion
crico-thyroid
membrane
Omo-hyoid muscle
Sterno-thyroid!
muscle
Crico-thyroid-
membrane
Crico-thyroid
muscle
THYROID GLAND
Right common
carotid artery
RIGHT PNEUMO-
GASTRIC NERVE
Right internal
jugular vein
Level of sternum.
SECTION OF CLAVICLE-
SECTION OF FIRST RIB-
Sterno-mastoid
muscle
-CRICOID CARTILAGE
FIRST RING OF TRACHEA
TRACHEA
Left suspensory
ligament
LEFT RECURRENT
NERVE
Esophagus
Left innominate vein
LEFT LOBE OF THYMUS
SECTION OF STERNUM.
Left internal
mammary artery
LEFT LUNG
Pericardium
SECTION OF FIFTH RIB
CARTILAGE
ENSIFORM CARTILAGE
Structure. A thin areolar capsule invests the lobes of the thyroid gland, and
extends upwards in the form of two flattened fibrous bands to be attached to each
lobe of the thyroid body. These bands are well marked at the period of birth, and
seem to act as suspensory ligaments. If the capsule is removed, it is seen to send
inwards numerous prolongations from its deep surface, which pass between the
lobules to surround and connect them.
The lobules are irregular and many-sided, and consist of numerous lymph
follicles. They are grouped around a central tubular cord of connective tissue, and
VOW THYMUS GLAND
957
when unravelled the lobe can be lengthened out, the lobules then appearing to be
attached to the cord in a spiral fashion.
The vessels. The arteries are derived from the internal mammary and from
the superior and inferior thyroids.
FIG. 541. THYMUS GLAND IN A CHILD AT THE AGE OF TWO YEARS.

THYROID CARTILAGE
Central portion of crico-
thyroid membrane
Crico-thyroid muscle
FIRST RING OF TRACHEA
THYROID BODY
SEVENTH RING OF TRACHEA
Right carotid artery
Right subclavian artery
Right innominate vein
THYMUS GLAND
Vena cava superior
Ligament connecting
thyroid and thymus
bodies
Left carotid artery
lo abia all
Left subclavian artery
LOBE OF THYMUS PASSING
BEHIND VEIN
Left innominate vein
Arch of aorta
Arch of aorta
The veins join the left innominate and thyroid veins.
The nerves are very minute, and proceed from the sympathetic and pneumo-
gastric.
958
THE ORGANS OF RESPIRATION
THE ORGANS OF RESPIRATION
THE LUNGS
The lungs which are two in number-are the special organs of respiration, and
occupy the greater portion of the chest cavity. They are separated one from the
other by the heart and great vessels, and the other contents of the mediastinal
spaces.
THE PLEURE
Each lung is closely invested by a delicate serous covering, which also dips into
and lines the fissures which separate their lobes-the visceral layer of the pleura,
or pleura pulmonalis.
The parietal layer, or pleura costalis, is reflected from the root of the lung
forwards, covering the side of the pericardium, to the chest-wall in front, and
backwards to the sides of the vertebral column, whilst below it covers the vault of
the diaphragm. The pleural cavity between the two layers just described does
not exist except as a result of disease or injury; air or fluid may then separate
them one from the other and fill the intervening space.
Below the root of each lung a fold of the pleura descends to the diaphragm, the
ligamentum latum pulmonis. The pleural sacs pass for an inch or more above
the level of the first rib beneath the scalene muscles, covering the apices of the
lungs, and the parietal layer is here strengthened by a dome of fascia which descends
from beneath the muscles to the inner border of the first rib. The interval between
the two sacs is considerable both above and below; but opposite the second piece
of the sternum, corresponding with the second, third, and fourth rib cartilages
(fig. 521), they are closely approximated or in actual contact.
The right pleural sac, though shorter and wider than the left, reaches as a rule
somewhat higher in the neck. The inner surface of the pleura, where the two
layers are in contact, is smooth and moist and glistening; the outer surface
is closely adherent where it invests the lungs, the pulmonary vessels, and the
diaphragm; but elsewhere it may be easily detached, and it is, moreover, much
thicker, and presents a rough surface.
The pleuræ leave a narrow rim at the circumference of the diaphragm uncovered
and in direct contact with the chest walls.
The lungs are somewhat pyramidal in shape, with their bases below and their
apices projecting upwards to the root of the neck.
Each lung presents an outer and an inner surface, separated by an anterior and
a posterior border, with a base and an apex.
The outer surface is convex, and mainly corresponds to the concavity of the
inner surface of the lateral wall of the thorax.
The inner surface is concave, and comes into contact with the pericardium and
lateral pleural wall of the mediastinal spaces.
The posterior border is the longer; it is thick, rounded, and smooth, and
occupies the groove on the side of the vertebral column.
The anterior border is thin, irregular, and sharply edged, and is deeply notched
in the left lung, leaving the pericardium uncovered.
The base is concave, and rests on the corresponding arch of the diaphragm;

MOTE THE PLEURE
959
FIG. 542.-ANTERIOR VIEW OF FETAL HEART, VESSELS, AND LUNGS.

SUPERIOR LOBE OF RIGHT LUNG
Aorta
Pulmonary
artery
RIGHT AURICULAR
APPENDIX
MIDDLE LOBE
INFERIOR LOBE
BASE
DUCTUS ARTERIOSUS
Pulmonary
artery
SUPERIOR LOBE OF
LEFT LUNG
LEFT AURICULAR
APPENDIX
Pulmonary
artery
INFERIOR LOBE
Descending aorta
FIG. 543.-ANTERIOR VIEW OF THE THORAX WITH CHEST WALL REMOVED, SHOWING
THE LUNGS. (Modified from Bourgery.)

Cut edge of pleura
SUPERIOR LOBE
PERICARDIUM
MIDDLE LOBE
INFERIOR LOBE
Diaphragm
O
LEFT LUNG
CLAVICLE
O
Pectoralis major muscle
Pectoralis minor muscle
SUPERIOR LOBE
Serratus magnus
muscle
INFERIOR LOBE
SECTION OF SEVENTH RIB
STERNUM
ENSIFORM CARTILAGE
960
THE ORGANS OF RESPIRATION
whilst the apex passes above the first rib to lie beneath the subclavian artery. The
lungs are divided into two lobes by a deep fissure which passes obliquely upwards
and inwards almost to the root of the organ. This fissure commences at the
posterior border, about 7.5 cm. below the apex, and, sweeping round the convex
surface of the lung, ends near the anterior border below.
In the right lung a second fissure passes from the anterior edge to reach the
main fissure near its centre, marking off a third or middle lobe.
The right lung is somewhat larger than the left; it is also shorter, and, as just
mentioned, possesses three lobes.
FIG. 544.-POSTERIOR VIEW OF THE THORAX WITH CHEST WALL REMOVED, SHOWING
THE LUNGS. (Modified from Bourgery.)

TRACHEA
Pericardium
Cut edge of pleura
CESOPHAGUS.
Cut edge of pleura
LEFT
LUNG
RIGHT LUNG
Supra-spinatus muscle
SPINE OF SCAPULA
Infra-spinatus muscle
Diaphragm
Above the middle of the inner surface, but nearer to the posterior border, each
lung is connected to the pulmonary vessels and bronchi by means of its root.
The root of the lung is composed of the pulmonary artery and the pulmonary
vein with the corresponding bronchial tube; and, in addition, the bronchial vessels,
the anterior and posterior pulmonary plexuses with some bronchial lymphatic
glands and areolar tissue the whole of which are encased in a pleural covering.
The right root lies behind the superior cava and upper portion of the right
auricle of the heart; above, the vena azygos major arches to join the superior cava.
In front is the anterior pulmonary plexus, and more anteriorly the phrenic nerve.
Behind is the posterior pulmonary plexus and the pneumogastric nerve, whilst below
is the ligamentum latum pulmonis.
THE LUNGS
961
The left root has the pulmonary plexus and left phrenic in front; above it is
the arch of the aorta; behind, the descending aorta and pneumogastric nerve with
the posterior pulmonary plexus; whilst below stretches downwards the ligamentum
latum pulmonis.
The chief structures contained within the root vary on the two sides.
From above downwards on the right side, they lie as follows-bronchus,
artery, and vein; whilst on the left side the artery is the highest, the bronchus is
FIG. 545.-ANTERIOR VIEW OF THE LUNGS: PERICARDIUM. (Modified from Bourgery.)

Vena cava superior
BRONCHUS
Pulmonary artery
Pulmonary vein
Arch of aorta
Pulmonary artery
BRONCHUS
Pulmonary vein
PLEURA
PERICARDIUM
ENSIFORM CARTILAGE
LEFT
DIAPHRAGM
placed next, and the vein is again the lowest. From before backwards on both
sides, the arrangement is-bronchus, artery, and vein.
The weight of the lungs together is about forty-two ounces; the right lung is
about two ounces heavier than the left.
In colour the lungs are of a pinkish white; but they become darker, mottled, and
even black, as age advances.
Structure. The lungs possess an external serous coat derived from the pleura,
beneath which is a delicate subserous layer.
3Q
962
THE ORGANS OF CIRCULATION
The parenchyma, or lung substance, is composed of minute lobules connected
by interlobular areolar tissue. Each lobule is made up of a ramification of a bron-
chial tube with its cluster of terminal air cells, with a minute plexus of pulmonary
and bronchial vessels, nerves, and lymphatics.
The vessels. The pulmonary arteries convey venous blood from the heart to the
lungs; they divide into branches which follow the bronchial tubes, and finally termi-
nate in a flat meshwork upon the walls of the intercellular passages and air cells.
The radicles of the pulmonary veins start from this network, and, coalescing
into larger branches which accompany the arteries, return the arterial blood to the
left auricle of the heart.
The bronchial arteries are the nutrient vessels of the lung. They commonly
arise by a single or by separate trunks from the thoracic aorta. Some branches
ramify in an open plexus outside the lung beneath the pleura; another set supply
the interlobular areolar tissue; whilst a third set of branches supply the bronchial
tubes with their lining membrane and muscular walls, the walls of the vessels, and
the bronchial glands. The ramifications of this set reach and mingle with the
pulmonary vessels, and thus a small quantity of the blood conveyed by the bronchial
arteries is returned as arterial through the pulmonary veins to the heart.
The bronchial veins consist of a superficial and a deep set, which join, to empty
on the right side into the vena azygos major, and on the left into the superior
intercostal.
The lymphatics form a superficial and a deep set.
The nerves are derived from the anterior and posterior pulmonary plexuses.
THE ORGANS OF CIRCULATION
THE PERICARDIUM
The pericardium is a cone-shaped, fibro-serous sac surrounding the heart, with
its apex above, and its base below and adherent to the diaphragm. The fibrous
layer is very strong and inelastic, and is composed of interlacing fibres. Below,
its connection with the central tendon of the diaphragm is close and intimate. It
is very firmly bound to the caval opening, but loosely attached and easily separable
elsewhere. Above, it is lost on the sheaths of the great vessels, all of which receive
distinct investments, with the single exception of the inferior vena cava, which
pierces it from below.
The aorta, superior vena cava, both divisions of the pulmonary artery, with
the ductus arteriosus, together with the four pulmonary veins, are all ensheathed
in this manner. The fibrous portion of the pericardium through the sheaths,
prolonged over the great vessels, ultimately becomes continuous above with the
deep cervical fascia. Two slight bands of fibrous tissue the sterno-pericardial
bands or ligaments-connect the front of the pericardium, above and below, with
the posterior surface of the sternum.
The serous layer is smooth and glistening. It lines the fibrous bag to form
its parietal portion, and is reflected over the surface of the heart at the roots of
the great vessels to form its visceral portion, the two layers being in close contact,
and moistened with a thin secretion to allow the free movement of the heart. A
series of pouches or sinuses are thus formed at the line of reflexion.
Between the
inferior vena cava and lower left pulmonary vein, the oblique sinus ascends
behind the left auricle, partially investing the pulmonary arteries and the pulmonary
PERICARDIUM-HEART
963
veins of the right and left sides, between which it passes. Small pouches from the
main sac dip between the veins to meet the inflexions from the sides of the oblique
sinus just noticed, thus completing the serous coverings to these vessels.
Pouches can be further traced between the inferior vena cava and lower pulmo-
nary vein of the right side, between the superior vena cava and upper pulmonary
vein of the same side, and also between the left pulmonary artery and left upper
pulmonary vein.
A tubular prolongation, moreover, surrounds both the root of the pulmonary
artery and the aorta in common, and these are the only vessels which can be said
to have a complete and continuous investment. The inferior vena cava receives a
very imperfect covering.
The vestigial fold of the pericardium is a doubling of the serous layer which
passes between the left pulmonary artery above and left pulmonary vein below.
It contains, besides some fatty and areolar tissue, the shrunken remains of the left
superior vena cava. It is connected above with the left superior intercostal vein,
and below with the left auricle and oblique vein of Marshall, these veins with
the coronary sinus having originally formed portions of the left upper cava.
Relations. In front are found the thymus gland or its remains, areolar tissue,
the sterno-pericardiac ligaments, the triangularis sterni muscle, the internal
mammary vessels, and sternum. Laterally, it is overlapped by the thin anterior
margins of the lungs with their pleural sacs, especially on the left side. Posteriorly
it is in relation with the bronchi, the oesophagus, and pneumogastric nerves, and the
descending aorta. On each side the pericardium is covered by the parietal layer
of the pleura, the phrenic nerve and its companion artery intervening. On opening
the pericardium the following structures may be observed: the greater part of
the right and a portion of the left ventricle with the interventricular sulcus, the
right auricle and right auricular appendix (the latter overlapping the root of
the aorta), the auriculo-ventricular sulcus; the first portion of the aorta with
the superior vena cava on its right side, and the pulmonary artery at first overlying
and then passing to its left side, with the tip of the left auricular appendix. If the
heart be raised upwards and to the right, its posterior surface is seen to consist of
the greater part of the left ventricle, and the remaining portion of the right, the
ventricular sulcus dividing the two. Lying transversely above the ventricle in
the auriculo-ventricular groove is the coronary sinus, receiving some of the cardiac
veins, and also the oblique vein of Marshall from the back of the left auricle, the
roots of the pulmonary veins, and the very small portion of the inferior cava above
the diaphragm, may also be noticed.
The two ventricles rest in about equal proportions on the central tendon of the
diaphragm. The main branches of the coronary arteries of the heart occupy
the grooves.
Vessels. The arteries of the pericardium are derived from the pericardiac,
œsophageal, and bronchial branches of the thoracic aorta, and from the internal
mammary and phrenic.

THE HEART
The heart-enclosed in the pericardium-occupies the greater part of the middle
mediastinal space. It is a somewhat flattened, cone-shaped, hollow, muscular organ.
Position. In the adult the heart lies obliquely behind the lower two-thirds of
the sternum, projecting considerably to its left side. Its base is directed slightly
upwards and backwards, and to the right; its apex downwards and forwards,
and to the left. The base corresponds to the sixth, seventh, and eighth thoracic
vertebræ; and the apex to the chest wall on the left side, between the fifth and
sixth rib cartilages.
322

964
THE ORGANS OF CIRCULATION
It may be mapped out on the chest wall in the following manner: a line drawn
across the sternum about the level of the third costal cartilages, half an inch to
the right and one inch to the left, will indicate the position of its base, from which
the great vessels arise.
The apex, as before observed, strikes the chest wall between the fifth and sixth
rib cartilages on the left side, at a spot about a couple of inches below the nipple,
and one inch to its sternal side.
The lower border is formed by the right ventricle and rests on the central
tendon of the diaphragm. It is defined by a line curving downwards, commencing
FIG. 546. ANTERIOR VIEW OF THE HEART WITH THE LARGER VESSELS.
(By permission. Museum of the Royal College of Surgeons.)
Left common
carotid artery Internal jugular vein
Right superior thyroid vein Left superior
Right common carotid artery
Internal jugular vein
Vertebral vein
thyroid vein
THYROID
BODY
Left vertebral vein
External jugular vein
Left subclavian vein
Subclavian vein
Inferior thyroid veins
Vena azygos major
Vena cava superior-
Aorta
Left innominate vein
Left superior intercostal
vein
DUCTUS ARTERIOSUS
Left pulmonary artery
and vein
LEFT AURICULAR APPENDIX
Right pulmonary-
artery
PERICARDIUM
RIGHT AURICLE
RIGHT VENTRICLE-
Vena cava inferior-
Aorta
Pulmonary artery
LEFT VENTRICLE
at the apex, and crossing close to the sterno-xiphoid articulation and terminating
at the right edge of the sternum near its junction with the sixth cartilage.
The lateral borders may be completed by drawing curved lines upwards from
the points last named to the ends of the basal line. The right border consists
entirely of the right auricle, and the left of the left ventricle.
Size and weight. In the adult the heart measures about five inches from base
to apex, three and a half inches across where it is broadest, and two and a half at
its thickest portion. In the male its weight averages about eleven ounces, and in
the female about nine ounces. It increases both in size and weight up to advanced
life, the increase being most marked up to the age of twenty-nine years.

THE HEART SAGHT
965
The anterior surface of the heart is convex, and looks upwards and forwards.
Its lower and posterior surface, which rests partly on the diaphragm, is flattened.
The borders which divide the two surfaces of the heart meet near the apex; the
right border is thin and rather longer than the left, whilst the latter border is thick
and rounded.
The auricles are divided from the ventricles by a transverse groove, the
auriculo-ventricular, which is interrupted in front by the origin of the pulmonary
FIG. 547.-SHOWING THE POSITION OF THE HEART AND ITS VALVES IN RELATION
TO THE CHEST WALLS.
(Reduced from Hensman and Fisher's Anatomical Outlines.')
(The right auricle and ventricle, with the pulmonary semilunar and tricuspid valves, are outlined
in blue tints; whilst the left auricle and ventricle, with their corresponding valves, are indicated
in red.)
X
XI
XII
VII
VI
11
11
IV
V
VE
VII
X
XI
XII
artery. The ventricles are similarly divided from each other by the inter-
ventricular groove, which runs obliquely on the anterior and posterior surfaces of
the heart, meeting below just to the right of the apex where they are continuous.
The grooves are placed near the borders of the heart, so that the right ventricle
is mainly anterior, and the left posterior.
Of the four cavities into which the heart is divided, the right auricle and
ventricle constitute its venous side, whilst the left auricle and ventricle belong to
its arterial side.
The right auricle receives the venous blood of the body through the two venæ
966
THE ORGANS OF CIRCULATION
cave, and of the heart through the coronary sinus, and transmits it into the right
ventricle. The right ventricle in turn transmits the venous blood to the lungs
through the pulmonary artery. From the lungs it is returned arterialised to the
left auricle of the heart by the pulmonary veins. From the auricle it passes into
the corresponding ventricle, and thence through the aorta and its branches to all
parts of the body, including the heart itself.
The right auricle.-The right auricle is lined by a smooth and delicate
membrane, the endocardium, which is continuous with the inner coats of the
blood-vessels. It presents a large quadrangular cavity, the sinus venosus or atrium,
and one much smaller within the auricular appendix. The auricle forms the
right and fore part of the base of the heart.
Openings. Of the three chief openings, that of the superior cava appears at
FIG. 548.-TRANSVERSE SECTION PASSING THROUGH THE AURICLES OF THE HEART,
SHOWING THE AURICULO-VENTRICULAR ORIFICES AND THE SEMILUNAR VALVES
OF THE PULMONARY ARTERY AND AORTA. SEEN FROM ABOVE.
(The portions of the auricles removed are seen in fig. 552.)
ANTERIOR SEGMENT OF PULMONARY SEMILUNAR VALVE
Right auriculo-ventricular
orifice and tricuspid valve

323
Left auriculo-ventricular orifice
and mitral valve
CHORDÆ TENDINEÆ
POSTERIOR SEGMENT OF AORTIC SEMILUNAR VALVE
Vena cava
the upper and back part of the cavity; whilst at the lower and back part is the
opening of the inferior cava. The right auriculo-ventricular opening, which leads
into the ventricle, is placed below and in front; whilst above and in front the cavity
is prolonged into the auricular appendix.
The orifice of the coronary sinus lies between the lower caval and auriculo-
ventricular openings. Besides these there are about a score of small scattered
orifices, known as the foramina Thebesii.
The superior caval opening is valveless, and is directed downwards and forwards
towards the auriculo-ventricular opening.
The inferior caval opening is somewhat larger, and is directed upwards and
inwards. It is usually guarded by a semilunar fold, the Eustachian valve, which
is much larger in foetal life, and which then serves to direct the current of blood
through a foramen in the wall dividing the two auricles. It is attached by its

THE HEART
967
convex margin to the front and left side of the vein, its free concave edge looking
upwards and to the right. The left cornu or horn of the crescent is continuous
with the anterior edge of the annulus ovalis, whilst the right horn is lost on the
auricular wall. The Eustachian valve contains interlacing muscular fibres; it is
often very incomplete and sometimes perforated.
FIG. 549.-ANTERIOR VIEW OF THE RIGHT CHAMBERS OF THE HEART, WITH THE
GREAT VESSELS.

Vena cava superior
RIGHT AURICULAR
APPENDIX
Orifice of vein
of Galen
Left carotid
Innominate-
Arch of aorta_
Left subclavian
Right pulmonary artery
Ductus arteriosus
Left pulmonary artery
Pulmonary artery
Pulmonary semilunar valves
ANNULUS OVALIS
LEFT AURICULAR APPENDIX
Small papillary muscle connected
with septum
(1) Columna carnea
CHORDE TENDINEÆ
Anterior papil-
lary muscle
Left coronary
FOSSA OVALIS
VALVE OF EUSTACHIUS
Vena cava inferior THEBESIUS
ANTERIOR SEGMENT OF TRICUSPID VALVE
RIGHT SEGMENT OF TRICUSPID VALVE
SECTION OF VENTRICULAR WALL
Vena cava inferior
artery
(2) Columna carnea
(3) Posterior papillary muscle
The coronary sinus returns the blood from the heart substance, and is guarded
by a semilunar or sometimes double valve, known as the coronary valve, or valve
of Thebesius. Like the Eustachian, it is formed of a fold of the endocardium, and
serves to direct the blood current, but does not prevent regurgitation. It is some-
times perforated, and occasionally presents the most delicate lacework.
The foramina Thebesii.-The greater number of these small orifices end
968
THE ORGANS OF CIRCULATION
blindly, but the rest are the terminations of minute veins from the muscular
substance (venæ minimæ cordis). One of these, more constant than the others, the
vena Galeni (right marginal), usually opens below the superior cava, on the septal
wall.
The cavity of the right auricle is smooth, except upon its anterior wall, and
within the appendix, where it is ridged with muscular bands (the musculi
pectinati).
At the lower part of the posterior wall or septum which divides the two auricles,
and just above the orifice of the inferior cava, is a smooth oval depression, the
fossa ovalis. It marks the position of the opening in the foetal heart, to be
described hereafter; and is bounded by a well-marked rounded edge, the annulus
ovalis. Beneath its margin a little valvular pouch may usually be noticed which
leads into a small orifice passing into the left auricle.
The tubercle of Lower-which is placed on the right of the cavity between the
orifices of the two cava-is well marked in some of the lower animals, but it is quite
an insignificant eminence in man.
The right ventricle forms the larger part of the heart in front, where it is

FIG. 550.-TRANSVERSE SECTION THROUGH THE HEART NEAR ITS APEX, SHOWING
THE RELATIVE THICKNESS OF ITS MUSCULAR WALLS, THE BULGING OF THE
SEPTUM TOWARDS THE RIGHT VENTRICLE, AND THE SHAPE OF THE CAVITIES.
Posterior
coronary artery
Section of
papillary
muscle
CAVITY OF RIGHT
VENTRICLE
SEPTUM
CAVITY OF LEFT
VENTRICLE
convex ; but below, where it rests upon the diaphragm, it is flattened. It forms
the whole of the lower border (margo acutus) of the heart, but it does not reach the
apex, which is formed entirely by the left ventricle.
In form the ventricle is triangular, its upper and left angle being continuous
with the root of the pulmonary artery; and upon opening the cavity the two are
seen to be continuous through a cone-shaped prolongation-the infundibulum or
conus arteriosus.
At the opposite angle there is a second and larger opening, leading from the
right auricle, the auriculo-ventricular orifice. It lies below and to the right of the
pulmonary orifice. The apex of the ventricle points to the left.
The two openings just named are guarded by valves and separated by a rounded
muscular projection of the ventricular wall. The inner surface, or body, of the
ventricle presents a somewhat complicated arrangement of muscular ridges, bands,
and columns, which become smaller, more numerous, and more closely interlaced
at the apex and near the margin, but which disappear in the infundibulum.
These projections, or columnæ carneæ, are usually divided into three sets:
TOYSLER THE HEART
969
(1) mere ridges; (2) bands attached at either end but elsewhere free; and (3) a third
set, the musculi papillares, which need a more detailed description (fig. 549).
A special band-the so-called moderator band, which is constant in the sheep-
is occasionally a well-marked structure in the human heart, stretching between
its anterior and septal walls. The musculi papillares are attached by their broad
ends to the ventricular wall, and by their extremities to tendinous cords (chordæ
tendineæ), which restrain and harmonise the action of the valves guarding the
auriculo-ventricular opening. Three of these are larger and more constant than
the rest: an anterior, connected with the front wall above the moderator band; a
right, near the margin, which is also attached to the anterior wall; and a posterior,
which arises from the septum. The septal wall of the ventricle so bulges into the
cavity as to make its cross-section appear crescentic.
THE OPENINGS AND THEIR VALVES
The orifice of the pulmonary artery is circular and obliquely placed at the
summit of the infundibulum near the septum. It is guarded by three valves, the
pulmonary semilunar valves. Of these one is placed anteriorly and to the left,
and two posteriorly; the right being somewhat in advance of the left (fig. 548).
FIG. 551.-INTERIOR VIEW OF THE AORTIC SEMILUNAR VALVES.

Sinus of Valsalva
Section of fibrous ring-
Free edge of valve.
Orifice of right coronary
artery
Corpus Arantii
Semilunar valve
Decussating fibrous
tissue of valve

Immediately above and behind each semilunar valve there is a pouch or sinus.
These collectively constitute the pulmonary sinuses, or sinuses of Valsalva.
Each valve is formed of a fibrous layer within a reduplication of the lining
membrane, which is continuous on the upper surface with the innermost coats of
the artery, and on the opposite surface with endocardium of the ventricle.
In the centre of the free straight edge of each valve there is a little fibro-carti-
laginous nodule, the corpus Arantii, and this margin is further strengthened by a
delicate tendinous band. Another fibrous band in like manner strengthens the
convex attached portion of the valve, and from this a third set of obliquely inter-
lacing fibres pass throughout the whole valve towards the nodule. Two narrow
crescent-shaped areas, the lunulæ, near the free edge on each side of the nodule,
remain almost free from this fibrous invasion, and it is these thinner portions
which are in apposition during closure of the valve. A fibrous ring strengthens the
pulmonary orifice, giving attachment below to the muscular fibres of the heart; whilst
above, opposite the sinuses of Valsalva, it is deeply hollowed into three semilunar
notches. The valves are attached to the edges of these notches as well as to the
horns which project inwards and separate them from one another. (See fig. 551, of
the aortic valves, in which these characters are present and more strongly marked.)

970
THE ORGANS OF CIRCULATION
The auriculo-ventricular opening is oval and guarded by the tricuspid valve.
The three triangular flaps of this valve are continuous with one another at their
broad ends, and so form a continuous fold around the orifice; but beyond, they
project with jagged and sharply dentated edges towards the apex of the ventricle.
The chordæ tendineæ, which chiefly arise from the papillary muscles already
described, pass to their free borders and ventricular surfaces. The largest segment
of the valve is placed in front, the smallest behind near the septum, and the third,
which is the most movable, is situated on the right between the two ventricular
openings.
Smaller segments intervene between the larger flaps. The chordæ tendineæ,
which arise in groups from the papillary muscles, divide as they pass to be attached
to the edges and ventricular surfaces of the neighbouring segments. Additional
cords are furnished from the ventricular walls, and especially from the septum to
the small segment, and some of these are provided with little papillary muscles.
The segments of this valve, except at the extremities and margins, contain
abundant fibrous, a small amount of muscular tissue, and they are attached by their
thickened bases to a fibrous ring which surrounds and strengthens the orifice.
FIG. 552.-VIEW OF THE AURICULAR CAVITIES FROM BELOW (THE TRANSVERSE
SECTION PASSING ABOVE THEIR MIDDLE).

Upper part of
cavity of left
auricle
AURICULAR WALL
Musculi
pectinati
Orifice of
superior
vena cava
Musculi
pectinati
-Right
auricular
appendix
The surfaces which look towards the opening are smooth, whilst upon the opposite
surfaces the chordæ tendineæ form an arched interlacement, which has been well
likened to the fan tracery of Gothic architecture. (Macalister.) oyber das.
The left auricle is placed behind the roots of the aorta and pulmonary artery,
with the right auricle overlapping it, and lying to the right of these structures.
Behind, it receives on each side the pulmonary veins. Its narrow and much
curved appendix arches round the root of the pulmonary artery, and is the only
part of the auricle to be seen from the front. The cavity of the auricle is
smooth, with the exception of the appendix, in which the musculi pectinati are well
marked.
Openings. Besides the narrow opening which leads from the atrium into the
appendix, the left auricle presents posteriorly the orifices of the four pulmonary
veins, two of which sometimes have a single mouth, whilst a third may be present,
and especially on the right side. The oval auriculo-ventricular opening is placed
below and in front. Several small orifices, the foramina Thebesii, are also to be
found in the cavity. A crescentic indentation on the septal wall, with its concavity
upwards and placed above the level of the annulus ovalis, indicates the upper
border of the valve, which has grown upwards to obliterate the foramen ovale,
2017 TO THE HEARTED LET
971
but which now is adherent and forms part of the wall dividing the two auricles.
As already observed, a small oblique orifice sometimes remains unclosed.
The left ventricle forms the chief part of the heart behind, with its apex and
left border. It is somewhat longer and narrower than the right, and in cross-section
its cavity appears oval.
FIG. 553.-POSTERIOR VIEW OF THE LEFT CHAMBERS OF THE HEART, WITH THE
GREAT VESSELS AND THE CORONARY SINUS LAID OPEN.

LEFT AURICULAR APPENDIX
INTERIOR OF LEFT AURICLE.
Great cardiac vein-
Valves of great cardiac,
vein
ANTERIOR
SEGMENT OF
MITRAL VALVE
Compound
anterior
papillary
muscle
FINE MESH--
WORK OF
COLUMNÆ
CARNEAE
AT APEX OF
VENTRICLE
Left carotid
Left subclavian-
Aorta-
COLUMNAE CARNEÆ
Innominate
Ductus arteriosus
Commencement of
left pulmonary
Left pulmonary veins
CONCAVE EDGE OF THE
VALVE OF THE FORA-
MEN OVALE
Right pulmonary
veins
Left auriculo-ventri-
cular opening
Valved orifice of vein
in coronary sinus
Coronary sinus
Valve of Thebesius
Vena cava inferior
POSTERIOR SEGMENT OF MITRAL
VALVE
CHORDA TENDINEÆ
Compound posterior papil-
lary muscles
Coronary artery
SECTION THROUGH WALL OF LEFT
VENTRICLE
The columnæ carneæ are numerous, small, and closely reticulated, giving to the
interior of the ventricle, especially near the apex, a cavernous appearance.
The musculi papillares are usually represented by two large, sometimes com-
pound, muscular pillars, which arise from the anterior and the posterior wall
respectively; and from these the chordæ tendineæ pass to the edges and surfaces of
the two segments of the bicuspid valve.
The orifice of the aorta looks somewhat forwards, and is guarded by three
972
THE ORGANS OF CIRCULATION
semilunar valves, which are similar in structure, but present more strongly marked
characters than are to be found in the corresponding valves of the pulmonary artery.
Two of these segments are placed anteriorly, the right being slightly in advance of
the left; and one is placed posteriorly and slightly to the right. It is surrounded
by a fibrous ring similar to that which strengthens the pulmonary orifice.
The auriculo-ventricular opening is guarded by the bicuspid valve. Its two
unequal segments are larger and thicker than those on the right side of the heart,
though the orifice itself is somewhat smaller, and they are similarly separated by
smaller lobes or cusps. Of the two segments, the one, which is the larger and the
more free and smooth, is placed in front and to the right between the two openings,
whilst the other lies behind and to the left. The fibrous ring surrounding the orifice
serves to give attachment to muscular fibres as well as to the valves. By its right
border it is tied to the aortic ring by fibrous tissue, which also extends to the ring
surrounding the tricuspid valve. In the angular space thus bounded there is
imbedded a fibro-cartilage, which in some mammals is represented by a bone which
is known as the os cordis.
THE POSITION OF THE CHIEF ORIFICES ONE TO THE OTHER AND
TO THE CHEST WALL
The pulmonary orifice is placed in front of, and to the left of the right auriculo-
ventricular opening, whilst the aortic orifice is in front of, and to the right of the
left auriculo-ventricular opening. The relation of the valved orifices to the chest
wall can only be approximately determined.
The pulmonary semilunar valves, which are anterior in position to the aortic,
are placed behind the junction of the third rib with the sternum on the left side.
The aortic semilunar valves, more deeply placed, correspond to the third space,
close to the sternum.
The tricuspid valve is situated behind the sternum near the middle line, about
the level of the fourth costal cartilage.
The mitral valve lies deeply behind the third intercostal space about an inch to
the left of the sternum.
The muscular walls of the heart vary very much in thickness, and the foetal
differs from the adult heart in the relative muscularity of its chambers.
The right auricle is thinner than the left, the right measuring about one-twelfth
of an inch, and the left about one-eighth of an inch in thickness. The right
ventricular wall in the adult is much thinner than the left, being thickest at the
base, and thinnest at the apex.
The left ventricular wall is about double the thickness of the right; and it is
thickest where it is broadest, being thinner both at its base and apex.

THE VESSELS AND NERVES
The arteries.-The two coronary arteries, right and left, arise from the aorta
just above the free borders of the right and left semilunar valves.
The right coronary artery passes forwards between the pulmonary artery and
the right auricular appendix, and then winds to the right border of the heart, around
which it turns to gain its posterior surface. In this course it lies in the auriculo-
ventricular groove. At the commencement of the posterior interventricular groove
it divides into its two main branches, one of which, still passing onwards in the
auriculo-ventricular groove, anastomoses with the left coronary, whilst the other
(interventricular) descends in the furrow between the ventricles towards the apex,
near which it anastomoses with branches derived from the left coronary artery
which have reached the posterior surface of the heart after passing around its apex.

THE HEART
973
In this course the right coronary artery supplies branches to the right auricle
(auricular) and roots of the pulmonary artery and aorta, as well as one that descends
near the right border of the heart (right marginal), and a second (preventricular)
to the anterior wall of the right ventricle. It supplies both ventricles and the septum.
The left coronary artery passes for a short distance forwards, between the
pulmonary artery and the left auricular appendix, and then divides into two prin-
cipal branches, one of which descends in the interventricular groove to the apex of
the heart (interventricular), around which it sends branches to anastomose with
FIG. 554.-SHOWING THE POSITION OF THE HEART AND ITS VALVES TO THE
CHEST WALL.
(Reduced from Hensman and Fisher's Anatomical Outlines.")
(The right auricle and ventricle, with the pulmonary semilunar and tricuspid valves, are outlined
in blue tints; whilst the left auricle and ventricle, with their corresponding valves, are indicated
in red.)
X
XI
VII
VI
IV
V
VE
VIL
XI
XII
XII
the right coronary; whilst the other winds to the back of the heart in the auriculo-
ventricular groove, to anastomose after division with the corresponding twigs of
the right artery. In this course it gives off a branch which descends near the left
border of the heart (left marginal), as well as smaller branches to the left auricle,
both ventricles, and the commencement of the aorta and pulmonary vessels.
The cardiac or coronary veins accompany the coronary arteries and return
the blood from the walls of the heart.
The (so-called) great cardiac vein ascends in the anterior interventricular sulcus,

974
THE ORGANS OF CIRCULATION
passing round the left side of the heart to its posterior surface in the auriculo-
ventricular groove to terminate in the commencement of the coronary sinus. Its
mouth is usually guarded by two valves, and it receives in its course the left
marginal vein, with other smaller veins from the left auricle (the left auricular)
and ventricle, all of which are guarded by valves.
The posterior cardiac vein (posterior interventricular), sometimes the larger
of the two chief veins, communicates with the foregoing at its commencement on the
anterior surface above the heart's apex. It ascends in the posterior interventricular
groove, receiving blood from the ventricular walls, and joins the coronary sinus
through an orifice guarded by a single valve close to its termination.
FIG. 555.-ANTERIOR VIEW OF THE HEART, SHOWING ITS ARTERIES AND VEINS.
Innominate
Right pulmonary vein
Left carotid
Left subclavian
Left pulmonary vein
-LEFT AURICULAR APPENDIX
RIGHT AURICLE
RIGHT AURICULAR APPENDIX
Right coronary
Branch to anterior wall
of right ventricle (pre-
ventricular)
Right marginal artery
and vein (vein of Galen)
Left marginal artery
Anterior interventricular
branch of the great car-
diac vein
Left coronary (interven-
tricular)
Commencing radicles of
posterior interventri-
cular vein
The anterior cardiac veins (preventricular) consist of several small branches
from the front of the right ventricle, which open separately into the right auricle,
or into the right auricular vein; and a right marginal vein (vein of Galen), which
joins the coronary sinus near its termination, or opens separately into the lower
part of the right auricle (figs. 549, 555).
The coronary sinus may be regarded as a much dilated terminal portion of the
great cardiac vein. It is about an inch in length, covered by muscular fibres from
the auricle, and lies in the auriculo-ventricular groove on the posterior surface of
the heart. Its cardiac orifice with the coronary (Thebesian) valve has already been
described. Besides the tributary veins already named, a small oblique vein of
Marshall may sometimes be traced from the vestigial fold to the sinus. This little
vein, which is not always pervious or easy of demonstration, never possesses a valve
at its orifice, and like the coronary sinus formed a part of the left superior vena
cava of early fœtal life. The sinus also receives the posterior interventricular vein,

THE HEART
975
one or more right auricular branches, and several post-ventricular veins from the
back of the left ventricle.
The cardiac nerves descend into the superior mediastinum, passing in front of
and behind the arch of the aorta, to unite in the formation of the superficial and
deep cardiac plexuses.
The deep cardiac plexus, the larger and more important, is placed immediately
above the pulmonary artery at its point of division, lying between the trachea and
transverse arch of the aorta. It is usually formed by the interlacement of all the
cardiac branches, with the exception of the left superior cardiac branch from the
sympathetic and the left inferior cardiac from the pneumogastric.
A meshwork of branches descends from the plexus, some passing to the right
FIG. 556.-POSTERIOR VIEW OF THE HEART, SHOWING ITS ARTERIES AND VEINS.
Left carotid artery
Left subclavian artery.
Right carotid artery
Innominate artery
Aorta
Ductus arteriosus
Pulmonary artery
Left pulmonary veins
LEFT AURICLE
Left coronary artery
Left marginal artery
Oblique line of Marshall
Left marginal branch of
the great cardiac vein
CUT EDGES OF THE LEFT
AURICULAR APPENDIX
Coronary sinus
Post-ventricular or smaller
posterior cardiac vein
Vena cava superior
Superior right pulmonary
vein
RIGHT AURICLE
Vena cava inferior
Right coronary artery
Posterior interventricular
or posterior cardiac vein
Posterior interventricular
branch of right coronary
artery
Anterior interventricular
branch of left coronary
artery
and some to the left. The greater number of the right branches follow the course
of the left coronary artery to form the anterior coronary plexus; some, however,
pass forwards to enter the superficial cardiac plexus.
The left branches, which are both larger and more numerous, descend beneath
the corresponding pulmonary artery to join the posterior coronary plexus; some of
these pass right and left to join the anterior pulmonary plexuses at the roots
of the lungs.
The superficial cardiac plexus, which lies in front of the right pulmonary artery
as it passes beneath the arch of the aorta, is formed by the interlacement of the left
superficial cardiac branch from the sympathetic, the inferior cardiac from the
pneumogastric, together with branches derived from the deep plexus. A small
ganglion, the cardiac ganglion of Wrisberg, is sometimes found close to the right

976
THE ORGANS OF CIRCULATION
FIG. 557.-ANTERIOR VIEW OF A FETUS. THE HEART, VESSELS, AND CHIEF ORGANS
DISPLAYED, WITH THE PLACENTA AND UMBILICAL CORD.
Umbilical vein
Ovary
Bladder
Suprarenal
capsule
Kidney
VOIT THE FETAL HEART
977
side of the ductus arteriosus. The filaments from this plexus form the greater
portion of the anterior coronary plexus. Some, however, reach the left anterior
pulmonary plexus.
The coronary plexuses follow the course of the vessels, and their filaments enter
the muscular walls of the heart. Minute ganglia are connected with these filaments,
and are especially abundant near the auriculo-ventricular groove.
PECULIARITIES OF THE FOETAL HEART
The foetal heart is at first almost vertical in position, but during the latter half
of intra-uterine life it gradually assumes the oblique position it retains in the adult.
Its weight in relation to the body varies considerably. Thus at the second
month it is about 1 to 50; at birth it is 1 to 120; whilst in the adult it is about
1 to 160.
The auricular portion is at first more capacious than the ventricular, and the
right auricle is larger than the left. The ventricular walls are at first about
equal in thickness, but at birth the left wall is the thicker of the two.
The foramen ovale is largest about the sixth month of intra-uterine life, and
there is up to this period a direct communication between the two auricles. The
valve of the foramen ovale, however, gradually advancing upwards beyond the
annulus, on its left side, acts as a perfect valve during the latter half of foetal life,
and thus prevents the return of blood into the right auricle.
The Eustachian valve has already been described; it is of large size in the foetal
heart, and serves to direct the current of blood from the inferior cava into the left
auricle.
The ductus arteriosus continues the pulmonary artery onwards to the concavity
of the arch of the aorta, to a point just beyond the origin of the left subclavian
artery, and so transmits the blood from the right ventricle into the descending
aorta. The ductus arteriosus during the growth of the pulmonary artery becomes
ultimately associated with its left branch.
The foetal circulation.--The right auricle of the heart receives its blood from
both venæ cavæ, as well as from the coronary sinus. That which is conveyed by
the superior cava is venous blood returned from the head and neck and upper
extremities. The inferior cava returns the blood from the lower half of the body,
as well as that which comes from the placenta through the umbilical vein. This
The black connecting arrows indicate the course of the circulation through the head and
neck, the upper extremities, the lungs, the liver, and the lower extremities.
The red arrows show the direction of the current from the placenta, through the
umbilical vein, ductus venosus (D.V.) and liver, to the upper portion of the inferior vena
cava.

The red arrows with the blue tails and the dotted line show the course of the less pure
blood, as it enters the right auricle through the inferior vena cava, and traverses the
foramen ovale, guided by the Eustachian valve, to gain the left auricle, left ventricle, and
aorta, to be distributed by its chief branches to the head and neck and upper extremities.
The blue arrows are placed on the superior and inferior vena cava, and some of their
main tributary trunks.
The stream derived from the superior cava passes through the right auricle-in front of
that already described-to reach the right ventricle; thence it passes into the pulmonary
artery (a small portion only reaching the lungs through the right and left pulmonary
branches), ductus arteriosus, and descending aorta.
The stream derived from the inferior cava mixes with the blood of the umbilical vein,
and that which has passed through the liver, beyond the junction of the ductus venosus
and hepatic veins.
The blue arrows with the red tails show the course of the blood through the descending
aorta to the lower extremities, and through the umbilical arteries to the placenta.
The colours of the arrows roughly indicate the proportion of pure and impure blood in
the different parts of the circulation.

3 R

978
THE ORGANS OF CIRCULATION
latter stream reaches the inferior cava, in part directly through the ductus venosus,
and in part through the liver and hepatic veins.
The blood of the superior vena cava passes from the right auricle into the right
ventricle, and thence through the pulmonary artery (a small portion only reaching
the lungs) and ductus arteriosus to the descending aorta. Through this trunk it
is conducted to the lower half of the body as well as to the placenta through the
umbilical arteries. From these parts it is returned to the right auricle by the
FIG. 558.-ANTERIOR VIEW OF HEART AND GREAT VESSELS OF FOETUS, THE ANTERIOR
CHEST WALL BEING REMOVED AND THE HEART SAC OPENED.
Ductus arteriosus.
Aorta
PERICARDIUM
REFLECTED
RIGHT AURICLE
Innominate
Left
carotid
Left
subclavian
SECTION OF CLAVICLE
Pulmonary artery
-LEFT LUNG
LEFT VENTRICLE
LEFT AURICULAR
APPENDIX
RIGHT LUNG
CUT EDGE OF
PERICARDIUM
Upper surface
of diaphragm
RIGHT AURICULAR RIGHT
APPENDIX VENTRICLE
inferior cava, which also receives the blood returning from the placenta as already
described.
The current which passes through the inferior cava only in a slight degree
mingles with that of the superior cava, as it is guided directly through the foramen
ovale by means of the Eustachian valve into the left auricle. This cavity also
receives a small quantity of blood (which has traversed the lungs) through the
pulmonary veins. From the left auricle the blood current passes into the left
ventricle, and thence through the aorta to the head and neck and the upper
extremities.

SECTION VIII
THE ORGANS OF DIGESTION
THE ORGANS ABOVE THE DIAPHRAGM
BY ARTHUR HENSMAN, F.R.C.S.
LECTURER ON ANATOMY AT THE MIDDLESEX HOSPITAL MEDICAL COLLEGE; AND SURGEON TO THE THROAT
AND EAR DEPARTMENT OF THE MIDDLESEX HOSPITAL.
THE MOUTH
HE mouth is the cavity at the commencement of the alimentary canal which
contains the organs of taste and mastication and the greater part of those of
speech. It communicates with the exterior through a transverse orifice (the buccal
orifice) and with the pharynx through the fauces.
It is bounded anteriorly and laterally by the teeth and alveolar arches; external
to which is a second cavity, often described as the vestibule of the mouth, which is
enclosed by the lips and cheeks. Its roof is formed by the hard palate, its floor by
the tongue, with the mucous membrane reflected from it to the inner surface of the
gums over the sublingual glands and the Whartonian ducts; and posteriorly it opens
into the fauces. It is lined by mucous membrane, which is continuous with that
of the pharynx, and at the outer margin of the lips is continuous with the skin.
The buccal orifice is a horizontal slit, the extremities or angles' of which are
opposite the first bicuspid teeth. The orifice is bounded by the upper and lower lips,
of which the former is distinguished by a median tubercle, the remains of the free
extremity of the fronto-nasal process. The lips are covered by a dry mucous
membrane, bright red in colour, and extremely sensitive, containing large numbers
of vascular papillæ, in many of which are nerve-terminations resembling touch-
corpuscles. Near to the junction of the skin and mucous membrane are numerous
sebaceous follicles, but these are devoid of hair-bulbs.
The substance of the lips consists of the orbicularis oris and a quantity of
areolar tissue in which are embedded the coronary vessels, lymphatics, and small
branches of the infraorbital and mental nerves. Around the orifice of the mouth
on its inner aspect, and placed beneath the mucous membrane, are a number of small
lobulated glands known as the 'labial glands.'
The cheeks consist of the buccinator muscle, covered externally, first by a stratum
of subcutaneous fat, then by the dermal muscles, zygomatici and risorius, and lastly
by the skin. They are lined with mucous membrane, which contains numerous
buccal glands similar to, but smaller than, the labial glands; and about five of larger
size, which, opening opposite to the last molar teeth, are known as the molar glands.
Between the integument and the mucous membrane, besides muscles, areolar tissue,
vessels, and nerves, there is in each cheek a large quantity of fat, which gives



3 R2

980
THE ORGANS OF DIGESTION
rotundity to the features, and constitutes what is sometimes spoken of as the
sucking cushion of the cheek. Opposite the second upper molar tooth is a papilla
which marks the opening of the duct of the parotid gland.
The gums are formed by a layer of tough areolar tissue covering the alveolar
processes, and firmly attached to their periosteum.
They are covered on both aspects by the mucous membrane of the mouth, the
inner surfaces receiving reflexions from the sides and anterior extremity of the
tongue, a median fold forming the frænum of that organ; and the outer surfaces
receiving reflexions from the cheeks and lips. In the median line above and below
the orifice of the mouth are folds of mucous membrane, forming the fræna
labiorum, of which the upper is the more marked.
МОЛЯНАТА Я
THE PALATE
ВИАРНО ЦЕТ
The palate consists of two portions, the anterior or hard palate, and the posterior
or soft palate.
The hard palate, which is limited in front and laterally by the alveolar
processes, ends posteriorly in a free border to which the soft palate is attached.
The mucous membrane which covers it is thick and somewhat pale, and is firmly
bound down to its periosteum. In the median line of the palate is a ridge called
the raphe; and at the anterior extremity of this is a small papilla which marks the
inferior opening of the anterior palatine canal. The mucous membrane covering
this receives its nerve-supply from the anterior palatine and naso-palatine nerves.
The SOFT PALATE (fig. 560) is attached to the posterior border of the hard
palate, of which it forms a backward prolongation hanging down at the back of
the mouth, and thus partially separating the latter cavity from the pharynx. Its
sides are merged in the pharyngeal wall, and its lower border is free.
From the centre of this border a somewhat conical process, the uvula, depends,
and from the base of this two folds of mucous membrane on each side extend in an
outward and downward direction, receiving the name of the pillars of the fauces.
The anterior pillar is formed principally by the palato-glossus muscle, and its
direction is downward, outward, and forward to the side of the base of the tongue.
The posterior pillar is formed principally by the palato-pharyngeus. It
approaches more nearly to its fellow of the opposite side than does the anterior. Its
direction is outward, downward and backward, and there thus exists between it
and the anterior pillar a triangular space, the tonsillar recess.
The space between the pillars is known as the isthmus of the fauces, and forms.
the buccal opening of the pharynx. It is bounded below by the tongue, above by
the soft palate, and laterally by the pillars of the fauces.
The anterior surface of the soft palate is concave, directed forwards and
downwards, and is continuous with the surface of the hard palate; its posterior
surface is convex, and is a continuation of the floor of the nasal cavity.
The soft palate is composed of a thin but rather dense fibrous aponeurosis,
certain muscles, vessels, and mucous glands covered by mucous membrane.
In the median line is a raphe which marks the junction of the two halves of
which the soft palate originally consists.
Muscles. The muscles of the soft palate are, on each side:-palato-glossus,
palato-pharyngeus, levator palati, and tensor palati; and, in the middle line, azygos
uvulæ, which divides above into two parts.
The Palato-Glossus is described on page 483.

THE PALATE
981
The Palato-Pharyngeus-named from its attachments-is a thin sheet.
Origin. (1) From the aponeurosis of the soft palate by two heads which are
separated by the insertion of the levator palati; (2) one or two narrow bundles
from the lower part of the cartilage of the Eustachian tube (salpingo-pharyngeus).
Insertion. (1) By a narrow fasciculus into the posterior border of the thyroid
cartilage near the base of the superior cornu; (2) by a broad expansion into the
fibrous layer of the pharynx at its lower part.
Structure. The upper head of the muscle consists of scattered fibres which
blend with the opposite muscle across the middle line; the lower head is thicker,
and follows the curve of the posterior border of the palate. The two heads with
the fasciculus from the Eustachian tube form a compact muscular band in the
posterior pillar of the fauces; the fibres mingle with those of the stylo-pharyngeus,
and then expand upon the lower part of the pharynx.
Nerve-supply. From the pharyngeal plexus.
Action.-(1) Approximates the posterior pillars of the fauces; (2) depresses
the soft palate; (3) elevates the pharynx.
The Levator Palati-named from its action on the soft palate-is somewhat
rounded in its upper, but flattened in its lower half.
Origin. (1) The under surface of the petrosal anterior to the orifice of the
carotid canal; (2) the lower margin of the cartilage of the Eustachian tube.
Insertion. The aponeurosis of the soft palate; the terminal fibres of the
muscle of each side meet in the middle line in front of the azygos uvulæ.
Structure. Its origin is by a short tendon; the muscle then becomes fleshy,
and continues so to its insertion.
Nerve-supply. It is usual to describe this muscle as being enervated by the
facial through the petrosal branch of the Vidian. The nerve is supposed to reach
the muscle in the branching of the posterior palatine. Stimulation of the facial
trunk within the skull of monkeys produces no result on the soft palate, whereas
stimulation of the eleventh causes elevation of the soft palate on the same side.
The motor branch probably passes to the palate in the upper branch of the pharyn-
geal plexus. (Horsley and Beevor.)
Action. (1) To raise up the palate, and bring it in contact with the posterior
wall of the pharynx; (2) when the muscle contracts it presses up and closes the
pharyngeal orifice of the Eustachian tube (Cleland). This action is not admitted
by many anatomists.
The Tensor Palati-named from its action on the soft palate-is a thin, flat,
and narrow sheet.
Origin. (1) The scaphoid fossa at the root of the internal pterygoid plate;
(2) the alar spine of the sphenoid; (3) the outer side of the pharyngeal extre-
mity of the Eustachian tube.
Insertion. (1) Into the transverse ridge on the under surface of the horizontal
plate of the palate bone; (2) the aponeurosis of the soft palate.
Structure. Its belly as it descends between the internal pterygoid muscle and
the internal pterygoid plate is muscular. On approaching the hamular process it
becomes tendinous, and continues so to its insertion. A bursa is interposed between
the hamular process and the tendon. The belly of the muscle is at nearly a right
angle with its tendon.
Nerve-supply. From the otic ganglion on the mandibular division of the fifth


nerve.
Actions. (1) Tightens the soft palate; (2) opens the Eustachian tube during
deglutition.
The Azygos Uvulæ-named because it was supposed to be a single muscle.
Origin. (1) From the aponeurosis of the soft palate; (2) the nasal spine of
the palate bone
-

982
THE ORGANS OF DIGESTION
4
Insertion.-Into the uvula.
Structure. The muscle consists of two narrow parallel strips lying on each
side of the middle line of the palate.
Nerve-supply. Probably from the same source as the levator palati.
Action.-To draw up the uvula.
The Mucous Membrane of the soft palate is continuous with that of the mouth
on its anterior aspect, and with that of the nasal chamber on its posterior surface;
its epithelium is columnar and ciliated in the vicinity of the Eustachian tube, but
elsewhere it is squamous and not ciliated. The glands form an especially thick
layer on its superior aspect.
Arterial supply of the soft palate.-(1) Ascending palatine of facial; (2) pala-
tine branch of ascending pharyngeal; (3) twigs from superior palatine of internal
maxillary, which enter the smaller palatine canals, and are distributed to the soft
palate and tonsils, and communicate with the ascending palatine of the facial
artery; (4) lingual artery, by twigs from the dorsal branch.
Nerves to the soft palate.-(1) Branches from Meckel's ganglion ('small or
posterior palatine' and 'external palatine nerve'); (2) tonsillitic branches of
glosso-pharyngeal nerve; and (3) the nerves supplying the muscles (p. 981).
The TONSILS (figs. 507 and 560) are two bodies situated one in each of the
recesses between the anterior and posterior pillars of the fauces. They are about
half an inch (15 mm.) in length, and one-third (8 mm.) in width and thickness; but
their size is liable to considerable variation.
On their inner surfaces are a number of puncture-like openings (twelve to fifteen
on each tonsil), which form the orifices of small recesses or crypts, into which
numerous follicles open. The mucous membrane is continued into, and forms a
lining for, these follicles; and their walls are surrounded by an aggregation of closed
capsules somewhat similar to the solitary glands of the intestine, and containing a
thick secretion.
The tonsil is in relation externally with the internal carotid and ascending
pharyngeal arteries, the superior constrictor intervening, and its position corresponds
to the angle of the lower jaw.
The arteries of the tonsil are five in number, viz. :-(1) Dorsalis linguæ from
the lingual; (2) ascending pharyngeal from the external carotid; (3) ascending
palatine from the facial; (4) tonsillar from the facial; and (5) descending palatine
from the internal maxillary.
The veins of the tonsil form a plexus which occupies the outer side of the gland.
The nerves of the tonsil are branches of the fifth and glosso-pharyngeal.
THE SALIVARY GLANDS
The three chief salivary glands are the parotid, the submaxillary (mandibular),
and the sublingual. These all pour their secretions into the cavity of the mouth,
into which also open a number of smaller glands to mix their contents with the
saliva.
The PAROTID GLAND, lying just below and in front of the ear-the largest of
the salivary glands-varies from a little over half an ounce to an ounce in weight.
Its superficial area is limited above by the root of the zygoma; behind, by
the auditory meatus, the mastoid process, and the sterno-mastoid muscle with the
posterior belly of the digastric; anteriorly, it extends for a varying distance over
THE SALIVARY GLANDS
983
f
the masseter muscle; and below, it is bounded by a line passing from the angle of
the jaw backwards. Its deep portion is in contact with the styloid process and its
muscles, and also with the sheath containing the internal carotid artery and internal
jugular vein.
The stylo-mandibular ligament separates the parotid from the submaxillary gland.
Processes or lobes pass from the body of the gland in various directions: one extends
forwards beneath the ramus of the mandible between the two pterygoid muscles; a
second passes inwards beneath the temporo-mandibular articulation, filling the back
of the glenoid cavity; and a third, forming the deepest portion of the gland, surrounds
the styloid process and passes between the carotid vessels. These have been named
respectively the pterygoid, glenoid, and carotid lobes. There is often in addition a
detached lobe, known as the socia parotidis. It is placed below the zygoma, and
above the main duct, into which it pours its contents by a separate channel.
The outer rounded surface of the parotid gland lies beneath the deep fascia,
FIG. 559. THE SALIVARY GLANDS.

SOCIA PAROTIDIS
DUCT OF SOCIA
PAROTIDIS
DUCT OF PAROTID
Bristle inserted.
into duct
Frænum linguæ.
DUCT OF RIVINI-
PAROTID GLAND
Masseter
muscle
Sterno-mastoid
muscle
Posterior belly
of digastric
muɛcie
LINGUAL
NERVE
SUBMAXILLARY
GLAND, DRAWN
BACKWARDS
Loop of fascia
SUBLINGUAL GLAND-
DUCT OF SUBMAXILLARY
GLAND
Mylo-hyoid muscle-
Anterior belly of
digastric muscle
DEEP PORTION OF SUBMAXILLARY GLAND/
HYOID BONE
superficial to which is the platysma and skin, with the facial branches of the great
auricular nerve.
Two or three lymphatic glands are placed on this surface.
From the upper part of the gland the temporal artery emerges to be joined by
the temporal branches of the auriculo-temporal nerve. The duct passes forwards
from its anterior border, with branches of the facial nerve and the transverse
facial artery.
Within the substance of the gland are found the following structures :-The
termination of the external carotid artery with the commencement of the temporal,
the transverse facial, the internal maxillary and posterior auricular arteries, all of
which supply branches to the gland; the temporo-maxillary vein, with a connecting
branch to the internal jugular, the facial nerve which crosses the artery in its
passage forwards and breaks up into the pes anserinus before emerging from the
anterior portion of the gland. There is a branch also of the great auricular nerve,

984
THE ORGANS OF DIGESTION
which penetrates the gland to join the facial. One or two lympathic glands,
commonly lie imbedded within the parotid.
The duct of the parotid (Stenson's) crosses the masseter a finger's breadth
below the zygoma. It penetrates the fat of the cheek and the fibres of the
buccinator muscle, between which and the mucous membrane it runs for a short
distance before it terminates, on the summit of a little papilla, by a minute orifice.
This opening is placed opposite the crown of the second upper molar tooth. The duct
commences by numerous branches, which converge towards the anterior border of
the gland, and receives in its passage across the masseter the duct of the socia
parotidis. Its canal is about the size of a crow-quill. Its mucous membrane is
lined by a columnar epithelium. The coat of the duct is thick and tough, and
consists of fibrous tissue intermixed with contractile fibres.
The arteries have been already described lying within the gland substance.
The veins have a similar distribution to the arteries.
The nerves are derived from the facial, great auricular, the carotid plexus of the
sympathetic, and the auriculo-temporal. The latter also conveys a branch derived
from the glosso-pharyngeal through the lesser petrosal and otic ganglion. The
lymphatics terminate in the superficial and deep cervical glands.
The parotid gland has been observed to retain its primitive condition, lying over
the mandible and masseter muscle. Its lobes are absent in early childhood.
The SUBMAXILLARY GLAND weighs about two drachms, and occupies the fore part
of the submaxillary triangle. It is covered by the skin, platysma, facial vein, the
inframandibular branches of the facial nerve, and the deep fascia; and it extends
upwards to occupy the submaxillary fossa, beneath the body of the mandible. The
anterior belly of the digastric lies in front; behind, the stylo-mandibular ligament
separates it from the parotid. The facial artery lies in a deep groove which occupies
its hinder and upper portion. Its deep surface is in relation with the mylo-hyoid in
front, and the hyo-glossus behind, with a few fibres of the stylo-glossus muscle
superiorly, and in addition the mylo-hyoid artery and nerve. The mylo-hyoid muscle
separates the submaxillary from the sublingual gland, and around the posterior free
border of this muscle a deep process of the gland turns forwards on the hyo-glossus.
Several lymphatic glands are found on the surface or imbedded within the glandular
substance.
The duct of the submaxillary gland (Wharton's) passes forwards and inwards
from the deep lobe just described, to open by a small orifice on the summit of a
papilla by the side of the frænum of the tongue. In this course it passes above
the lingual nerve. It lies at first between the mylo-hyoid and hyo-glossus; next,
between the mylo-hyoid and genio-hyo-glossus; and lastly, under cover of the mucous
membrane of the mouth, between the genio-hyo-glossus and the sublingual gland.
The duct is about two inches (5 cm.) in length, and has comparatively thin coats.
It is lined by columnar epithelium.

The
arteries to the gland are derived from the facial and lingual, with corre-
sponding veins.
The nerves proceed from the submandibular ganglion, from the mylo-hyoid of
the mandibular nerve, and from branches of the sympathetic.
The SUBLINGUAL GLAND-the smallest of the salivary glands-is about one
drachm in weight. It lies beneath the fore part of the tongue and mucous membrane
of the floor of the mouth, close to the frænum, deeply resting upon the mylo-hyoid
muscle. It is limited externally by the sublingual fossa of the mandible, and
internally by the genio-hyo-glossus and Wharton's duct; in front it touches its fellow;
and behind, it approaches the deep lobe of the submaxillary gland.
The duct from the main portion of the gland-the duct of Rivini-runs along-
side the submaxillary duct, to open with it on the same papilla. The fore part of
the gland consists of a cluster of little lobules, each with its own separate duct.
THE PHARYNX
985
They open in a line on the floor of the mouth. The innermost of the series very
commonly opens into the submaxillary duct.
The arteries are derived from the sublingual and submental, with their corre-
sponding veins.
The nerves are derived from the gustatory (through the submandibular ganglion)
and from the sympathetic.
THE PHARYNX
The pharynx is placed behind the nose and mouth, and extends from the base
of the skull to the lower part of the cricoid cartilage opposite the fifth cervical
vertebra. The soft palate projects into it from the front, dividing it into a nasal
portion above, and a buccal portion below.
The openings of the two posterior nares which are in front, and the orifices of
the two Eustachian tubes, one on each side, open into the naso-pharynx; whilst
into the buccal portion below the velum are the single openings of the mouth in
front, and the larynx and oesophagus below.
Thus there are seven openings leading into its cavity.
It measures from above downwards about four and a half inches (11.3 cm.),
and is flattened from before backwards, so that the cavity in this direction is
extremely contracted, its mucous membrane, especially above, being thrown into
numerous folds and recesses; whilst below the cavity becomes entirely obliterated,
for here its anterior and posterior walls, except during the act of swallowing, are
in actual contact. Thus it measures much more from side to side, being widest
opposite the cornua of the hyoid bone. It is narrowest below where it passes
into
the œsophagus.
The pharyngeal walls are composed of a fibrous coat, the pharyngeal aponeu-
rosis, lined by a mucous membrane, and surrounded externally by muscular layers
invested by a delicate areolar sheath which lies beneath the stronger post-pharyngeal
fascia.
The pharyngeal aponeurosis is well marked above, but below it loses its density
and gradually disappears as a definite structure. Above, it is attached to the
posterior portion of the body of the sphenoid bone in front of the pharyngeal
tubercle. Its attachment may be traced outwards to the apex of the petrous portion
of the temporal bone, to the cartilage which intervenes between it and the occipital
bone, and thence to the Eustachian tube and internal pterygoid plate.
The mucous membrane of the pharynx is continuous with the several cavities
which open into it. It is closely adherent to the base of the skull, thick and spongy
and dark in colour. It becomes thinner where it approaches the openings of the
posterior nares and Eustachian tubes, and below it is paler and folded longitudi-
nally. Lymphoid follicles and numerous racemose glands exist throughout the

mucous membrane.
The epithelium is ciliated and columnar in the naso-pharynx, but becomes
stratified and scaly in the lower portion.
Muscles. The muscular coat consists of the three constrictor muscles, with
additional fibres derived from the stylo- and palato-pharyngei muscles.
The inferior constrictor is thick and strong. It arises from the thyroid carti-
lage immediately behind the oblique line and superior tubercle, and also from the
inferior cornu and the side of the cricoid cartilage behind the crico-thyroid muscle
(fig. 524). The fibres spread backwards and inwards, the lowest horizontally,

986
THE ORGANS OF DIGESTION
whilst those above ascend more and more obliquely, and are inserted into the
fibrous raphe of the pharynx. Some of the lowest fibres are continuous with the
muscular fibres of the oesophagus, and the upper overlap the middle constrictor.
Near the upper border the superior laryngeal nerve and artery pierce the thyro-
hyoid membrane to reach the larynx. The recurrent laryngeal nerve ascends
beneath the lower border immediately behind the crico-thyroid articulation.
The middle constrictor is a fan-shaped muscle which arises from the lesser cornu
of the hyoid bone, the whole length of the greater cornu, and from the stylo-hyoid
ligament. The diverging fibres are inserted into the median raphe, and blend with
those of the opposite side. The lower fibres of the muscle descend beneath the
inferior constrictor to the lower part of the pharynx; the upper overlap the superior
constrictor, and reach the basilar process of the occipital bone; whilst the middle
fibres run transversely.
The stylo-pharyngeus and glosso-pharyngeal nerve pass downwards above its
FIG. 560.-SECTION SHOWING THE POSTERIOR WALL OF THE PHARYNX, WITH THE
PHARYNGEAL BURSA, FAUCES, ETC.
SECTION THROUGH POS--
TERIOR PORTION OF
BODY OF SPHENOID
BONE
Internal carotid artery-
SECTION OF CARTILAGE OF-
EUSTACHIAN TUBE
EUSTACHIAN ORIFICE
SECTION OF EUSTACHIAN-
TUBE
Tensor palati muscle-
Levator palati muscle.
Sphenoidal sinus
NASAL BONE
MIDDLE TURBINAL BONE
PHARYNGEAL BURSA AND
NASO-PHARYNX
INFERIOR TURBINAL BONE
SOFT PALATE.
BUCCAL PORTION OF PHARYNX
-ANTERIOR PILLAR OF FAUCES
-TONSIL
upper border, and near its origin it is overlapped by the hyo-glossus and crossed by
the lingual artery.
The superior constrictor is quadrilateral in shape, pale and thin. It arises
from the lower third of the hinder edge of the internal pterygoid plate and its
hamular process, from the pterygo-mandibular ligament, from the posterior fifth of
the mylo-hyoid ridge of the mandible, and from the side of the tongue. The fibres
pass backwards to be inserted into the median raphe, the highest reaching the
pharyngeal spine. The Eustachian tube and the levator palati muscle are placed
above the superior arched border, and the space between this and the basilar process,
devoid of muscular fibres, is strengthened by the pharyngeal aponeurosis. It is
semilunar in shape, and named the sinus of Morgagni.
THE ESOPHAGUS
987

The stylo-pharyngeus arises from the base of the styloid process internally.
It passes downwards and inwards to reach the pharynx between the superior and
middle constrictors. Its fibres spread out as it descends beneath the mucous
membrane. Some join the fibres of the palato-pharyngeus to be inserted into
the posterior border of the thyroid cartilage, and the rest interblend with the
constrictors.
The palato-pharyngeus is described with the muscles of the soft palate
(pages 981 and following).
The muscular coat of the pharynx is supplied by the pharyngeal plexus and
the external and recurrent laryngeal nerves. The stylo-pharyngeus is supplied by
the glosso-pharyngeal nerve.
Relations. The pharynx is loosely connected by areolar tissue with the pre-
vertebral fascia, the longus colli, and the rectus capitis anticus major muscles,
and vertebral column. Laterally, it is in relation with the styloid process and its
muscles, the glosso-pharyngeal nerve, the lateral lobes of the thyroid gland, the
sheath of the carotid vessels, the pharyngeal plexus and ascending pharyngeal
artery; above, it is separated from the ramus of the mandible and internal ptery-
goid muscle by a cellular interval; and beneath its investing fascia there is a plexus
of veins.
The interior of the pharynx, viewed from behind, presents the seven openings
already named. At its upper and back part the mucous membrane forms a rounded
projection which corresponds to the anterior recti muscles, and on each side of this
it sinks backwards, beneath the tip of the petrous portion of the temporal bone, to
form a cul-de-sac known as the pharyngeal recess.
In the roof of the cavity just below the body of the occipital bone and in the
middle line, the mucous membrane dips into a little pouch with a contracted orifice,
the pharyngeal bursa. It is the persistent lower portion of the pharyngeal
diverticulum (pouch of Rathke). It is easily demonstrated in the foetus and young
child, but commonly entirely disappears in the adult.
Stretching across the pharyngeal wall between the Eustachian orifices and
above the pharyngeal bursa, there occurs a special group of lymphatic follicles.
It extends indefinitely upwards towards the roof of the cavity, and constitutes
the pharyngeal tonsil. This portion of the naso-pharynx is exceedingly liable to
become swollen and chronically thickened in naso-pharyngeal catarrh.

THE ESOPHAGUS
The oesophagus is that portion of the alimentary tract which extends between
the pharynx and the stomach. It is more constricted than the rest of the canal,
being narrowest at its commencement opposite the sixth cervical vertebra and lower
border of the cricoid cartilage. It is again somewhat contracted in its passage
through the diaphragm, which is opposite the upper border of the eleventh thoracic
vertebra. It is nine or ten inches (25 cm.) in length, and in its course downwards
follows the curves of the vertebral column, until it finally passes forwards in front
of, and slightly to the left of the aorta to gain the oesophageal opening in the dia-
phragm. In addition to these curves it presents two lateral curvatures towards the
left side, at the root of the neck, and also below where it leaves the vertebral column.
It is placed in the middle line at its commencement opposite the fifth cervical
vertebra, and again, at a lower level, opposite the fifth thoracic vertebra.
Relations in the neck. The oesophagus has in front of it the trachea, the

988
THE ORGANS OF DIGESTION
posterior portion of the left lateral lobe of the thyroid gland, and the left recurrent
laryngeal nerve. Behind, it rests upon the vertebral column, the left longus colli
muscle, and prevertebral fascia.
On its right side are placed the right carotid and right recurrent nerve; and on
the left side the left inferior thyroid vessels, left carotid artery, left subclavian, and
thoracic duct. The recurrent nerves pass upwards on each side to gain the interval
between the trachea and oesophagus. The left nerve, as already described, at first
lies in front of the tube, and the right at some little distance from it.
In the thorax the œsophagus descends through the superior and posterior
mediastina. In front are the following structures :-the lower part of the trachea
with the commencement of the left bronchus, the transverse arch of the aorta,
left carotid and left subclavian arteries. Below is the posterior surface of the
pericardium. Behind, it is in relation with the vertebral column, longus colli muscle,
the thoracic duct, the right intercostal vessels, the left lower azygos vein, and the
lower portion of the thoracic aorta.
Laterally it comes into contact with both pleural sacs and with the pneumo-
gastric nerves. Below the roots of lungs these form a plexus (the plexus gulæ)
surrounding the gullet; finally the left nerve gains the front, and the right nerve
passes to the back of the tube. The vena azygos major ascends on the right side,
and the aorta descends on the left.
After death the gullet is somewhat flattened from before backwards, but it is
more rounded during life. It is closed except during the passage of food, etc.
Structure. The wall of the oesophagus is composed of three coats-muscular,
submucous, and mucous. It is surrounded with elastic cellular tissue, loosely con-
necting it with the neighbouring structures, and freely permitting its distension.
The muscular coat is thick, red, and consists of striped muscular fibres in its
upper third or more. It is made up of two distinct layers.
The longitudinal fibres commence as three flattened bands: a strong anterior
arising from the ridge on the back of the cricoid cartilage (fig. 526), and two lateral
bands which blend with the fibres of the pharynx. These all unite into a conti-
nuous layer which passes below into the muscular coat of the stomach. Several
accessory bands have been described, connected with the trachea, left bronchus,
pericardium, and left pleura.
The circular fibres are continuous above with the inferior constrictor, and below
with the oblique fibres of the stomach; they form a uniform layer which becomes
somewhat obliquely disposed towards the middle of the gullet.
The submucous coat loosely connects the inner mucous and outer muscular
coats. It is the seat of numerous racemose glands whose ducts open on the surface
of the mucous membrane.
The mucous coat is thick, reddish above, paler below, and deeply folded longitu-
dinally. It presents numerous papillæ and contains racemose glands. It is lined
by a stratified squamous epithelium.
argadgos
THE PERITONEUM
989
THE ABDOMINAL VISCERA
BY FREDERICK TREVES, F.R.C.S.ENG.
SURGEON TO AND LECTURER ON ANATOMY AT THE LONDON HOSPITAL; MEMBER OF THE BOARD OF EXAMINERS
OF THE ROYAL COLLEGE OF SURGEONS; EXAMINER IN SURGERY AT THE UNIVERSITY OF CAMBRIDGE.
THE PERITONEUM
Its general character.-The peritoneum is a thin and delicate serous membrane
which lines the cavity of the abdomen from the diaphragm to the pelvic floor, and
invests or covers to a varying extent the viscera which that cavity contains.
Viewed in its very simplest condition, it may be regarded as a closed sac, the inner
surface of which is smooth and perfectly polished, while the outer surface is rough
and is attached to the tissues which surround it. Could it be possible for the
peritoneum to be removed entire from the body by some process of superhuman
dissection, it would appear simply as a huge thin-walled bag.
In the male subject the peritoneum forms actually a closed sac; but in the
FIG. 561.-TRANSVERSE SECTION OF THE PERITONEAL SAC AT ABOUT THE LEVEL
OF THE UMBILICUS.

DES.
COL.
M-COL.
S.I.
MES.
AO.
V.C.
AS.
COL.
female its wall exhibits two minute punctures, which correspond to the openings
of the Fallopian tubes. That part which lines the walls of the abdomen is termed
the parietal peritoneum; that which is reflected on to the viscera is the visceral
peritoneum. The disposition of the peritoneum may first be studied by noting its
arrangement as made evident in transverse sections of the abdomen at certain
levels.
The first section to be described shows the peritoneum in its simplest condition.
This is a transverse section through the body, at about the level of the upper
surface of the fourth lumbar vertebra, and therefore about the site of the umbilicus
(fig. 561). Starting on the inner surface of the anterior abdominal parietes, the

990
THE ORGANS OF DIGESTION
peritoneum is seen to cover the transversalis fascia, and indirectly the anterior
abdominal muscles; then, passing to the left, it lines the side of the abdomen,
until it reaches the descending colon. This it covers, as a rule, in front and on
the sides, though occasionally, as shown in the diagram (fig. 561), it forms a
meso-colon. Then it passes over the bodies of the vertebræ with the large vessels
upon them, and leaves the back of the abdomen to run forward to enclose the
termination of the small intestine, returning again to the spine. The two layers
thus form the mesentery, having between them the terminal branches of the superior
mesenteric vessels. It then passes over the right half of the posterior abdominal
wall, covering the ascending colon in front, and at the sides only, unless there be a
meso-colon, and then passes on to the side and front of the abdomen to the point
from which it was first traced.
In tracing the peritoneum in a section of the body (fig. 562) opposite the
stomach, at a level with the first lumbar vertebra, its course becomes more com-
plicated and difficult to follow.
In the section already given the peritoneum as a simple closed sac can be
readily conceived; but at the level now exposed the serous membrane has been so
introverted that there appear to be two sacs, one leading from the other. The
FIG. 562.-TRANSVERSE SECTION OF THE ABDOMEN AT THE LEVEL OF THE FORAMEN
OF WINSLOW.
GASTRO-HEPATIC OMENTUM
GASTRO-SPLENIC,
OMENTUM
STOMACH
AORTA
SPLEEN
NCREAS
VENA
CAVA
KIDNEY
IST.LUM
VERT.
00
F OF W.
KIDNEY
LIVER
lesser is indeed but a diverticulum or bulging from the greater, and the manner of
its formation is explained on page 1039. These two sacs are called the greater and
the lesser sacs of the peritoneum. They communicate through a narrow strait or
neck, the foramen of Winslow. The lesser sac or cavity is discovered behind the
stomach, so that on first opening the abdomen no trace of it is to be seen. It
extends downwards between the layers of the great omentum (though this part
of the lesser sac is always obliterated by adhesion in the adult). It extends
upwards to the under surface of the liver, and is limited behind by the posterior
abdominal wall; and below, behind the great omentum, by the transverse meso-
colon. Its disposition on vertical section is shown in fig. 563.
The foramen of Winslow is situated just below the liver; it looks forwards and
towards the right, and will readily admit one or two fingers. It is bounded above
by the caudate lobe of the liver; below, by the duodenum and hepatic vessels;
behind, by the vena cava; and in front by the gastro-hepatic or lesser omentum,
containing the structures passing to and from the liver.
left.
Starting at the foramen of Winslow, the lesser sac will be found to turn to the
If now the peritoneum be viewed in a transverse section of the body at the

THE PERITONEUM
991
level named, viz. through the first lumbar vertebra, it will be found that the section
has probably passed through the foramen of Winslow (fig. 562). Starting at the
front of the abdomen and going to the right, the peritoneum is seen to line
the anterior abdominal walls, to pass over the side of the abdomen, and to cover
the front of the right kidney; it then extends on to the vena cava, when it
becomes a part of the lesser sac; then along the back of the lesser sac, over the
aorta and pancreas, which separate it from the vertebral column; next it reaches
the anterior of the two internal surfaces of the spleen in front of the hilum. Here
it meets with another layer of peritoneum, and helps to form the gastro-splenic
FIG. 563.-DIAGRAM TO SHOW THE PERITONEUM AS SEEN IN A VERTICAL SECTION.
(Allen Thomson.)

LIVER
GASTRO-HEPATIC OMENTUM
STOMACH
FORAMEN OF WINSLOW
PANCREAS
DUODENUM
TRANSVERSE MESO-COLON
Aorta
TRANSVERSE COLON
MESENTERY
SMALL INTESTINE-
UTERUS
RECTUM
BLADDER-
omentum. Leaving the spleen, it changes its direction, and runs to the right to the
stomach, forming the posterior layer of the gastro-splenic omentum; it covers the
posterior surface of the stomach, and leaves its upper border to form the posterior
layer of the gastro-hepatic omentum, and then passes upwards and to the right to the
liver. In this transverse section it is only seen passing on the right to the hepatic
vessels, where it forms the posterior boundary of the foramen of Winslow. Here
it bends sharply round and forms the anterior layer of the gastro-hepatic omentum ;
and passing to the left reaches the stomach, which it covers in front. It then forms
the anterior layer of the gastro-splenic omentum, and once more reaches the spleen.
It
passes right round the spleen to the back of the hilum, where it is reflected on

992
THE ORGANS OF DIGESTION
to the left kidney (fig 562). From hence the peritoneum passes along the side and
front of the abdomen to the point from which it started. In this section the liver
is so divided as to appear separated from all connection with the other viscera and
the abdominal wall, and to be surrounded by peritoneum.
The course of the peritoneum in a longitudinal section of the body will now be
considered (fig. 563). Starting at the umbilicus, and passing downwards, the peri-
toneum is seen to line the anterior abdominal wall. Before reaching the pelvis it
covers also the urachus and obliterated hypogastric arteries, which can be seen to
form ridges beneath it. On reaching the os pubis it is reflected on to the upper part
of the bladder, covering it as far back as the base of the trigone; from thence it is
reflected on to the rectum, which it covers in front and at the sides on its upper part.
Between the bladder and rectum it forms the recto-vesical pouch. In the female
the peritoneum is reflected from the bladder on to the uterus, which it covers; it
then extends so far down in the pelvis as to pass over the upper part of the
vagina behind; from thence it extends to the rectum. The fold between the
vagina and rectum forms the recto-vaginal pouch, or pouch of Douglas. The
membrane has now been traced back to the spine.
Following it upwards, the sigmoid flexure will be found to be completely
covered by peritoneum, a meso-colon attaching the gut to the abdominal wall.
As seen in fig. 561, the ascending and descending colon in either loin are covered
by peritoneum, as a rule, in front and on the sides. A little higher up in the
median line the peritoneum passes forwards, to enclose the small intestine, and,
returning to the spine, forms the mesentery (fig. 563). It now passes over the
third part of the duodenum to the pancreas, from which point it again passes for-
wards to form the lower layer of the transverse meso-colon. It invests the transverse
colon below and partly in front, and then leaves it to pass downwards to take part
in the great omentum. Running downwards some distance, it returns again and
forms the anterior layer of the omentum. On reaching the stomach it goes over
the anterior surface, and at the upper border forms the anterior layer of the
lesser or gastro-hepatic omentum, which extends between the stomach and the liver.
It invests the inferior surface of the liver in front of the transverse fissure, and,
turning over its anterior border, covers the upper surface. At the posterior limit
of the upper surface it leaves the liver and goes to the diaphragm, forming the
superior layer of the coronary ligament. It covers the anterior part of the dome
of the diaphragm, and, once more reaching the anterior abdominal wall, can be
followed to the umbilicus, where it was first described. On reference to the dia-
gram (fig. 563), the student might be led to suppose that the two sacs as above
described are quite separate. This, of course, is not the case; but in a longitudinal
section of the body made anywhere to the left of the foramen of Winslow, it is
impossible to show the direct connection between the two sacs.
The peritoneum has only been traced in this longitudinal section so far as it
concerns the greater sac. It now remains to follow upon the same section such
part of the membrane as forms the lesser sac. The peritoneum here will be seen
to cover the posterior surface of the stomach; and from thence it runs upwards to
the liver, forming the posterior layer of the lesser or gastro-hepatic omentum. It
reaches the liver behind the transverse fissure. It covers only a part of its posterior
surface, and is reflected on to the diaphragm, forming the lower layer of the
coronary ligament. It now goes downwards over the hinder part of the dome of
the diaphragm to the spine, separated from the latter by the great vessels. On
reaching the pancreas it passes forwards, and forms the upper layer of the trans-
verse meso-colon. It then covers the upper half of the transverse colon, and
descending forms the innermost layer of the great omentum. It now ascends and,
arriving at the greater curvature of the stomach, passes on to its posterior wall.
At this point its description was commenced. From fig. 562 it will also be evident

THE PERITONEUM
993
that the peritoneum forming the lesser sac comes into contact with the spleen,
forms one layer of the gastro-splenic omentum, and is in relation with the upper
part of the left kidney.
The precise manner in which certain organs-such as the liver, the cæcum, the
duodenum, and the kidneys-are invested by peritoneum, is described in the account
of those viscera. To such accounts the reader is referred for a description of the
many 'ligaments' (such as those of the bladder and liver) which are formed by the
peritoneum.
The great omentum.-It will be seen that the great omentum is formed of four
layers of peritoneum, though this is quite impossible to demonstrate in an adult,
the individual layers having become adherent.
The great omentum acts as a sort of apron, protecting the intestines and
providing them with a heat-economising covering of fat. It is nearly quadrilateral
in shape, and is variable in extent.
In fig. 564 the great omentum is shown to be connected with the greater curva-
ture of the stomach on the one hand, and the transverse colon on the other. This
is the arrangement described in the text. Under certain conditions (as shown in
FIG. 564.-DIAGRAM TO SHOW THE PERITONEUM AS SEEN IN VERTICAL SECTION.
(Allen Thomson.)

LIVER
GASTRO-HEPATIC OMENTUM
STOMACH
MESO-COLON
TRANSVERSE COLON-
MESENTERY
FORAMEN OF WINSLOW
SMALL INTESTINE
fig. 563) the posterior layer of the great omentum returns to the posterior parietes,
and is independent of the transverse meso-colon. This variation is explained in
the account of the evolution of the peritoneum (page 1039).
Mr. Lockwood has made some investigations on the lengths of the transverse
meso-colon and great omentum in thirty-three cases. In twenty under the age of
forty-five, only one subject had a great omentum long enough to be drawn beyond
the pubic spine; in five, the omentum reached as far as the pubes. In the cases
beyond forty-five years, it was the exception rather than the rule to find an
omentum which could not be pulled beyond the lower limits of the abdomen.
The lesser or gastro-hepatic omentum consists of a double layer of peritoneum
extending between the lesser curvature of the stomach and the transverse fissure of
the liver. If the two anterior layers of the great omentum are traced upwards,
they are seen to enclose the stomach, and then join together again at the lesser
curvature to form the lesser or gastro-hepatic omentum (fig. 563). It is connected
above with the transverse fissure of the liver, below with the upper curvature of the
stomach; the left extremity encloses the oesophagus; the right border contains
the hepatic vessels, and is free and forms the anterior boundary of the foramen
of Winslow.
3 S

994
THE ORGANS OF DIGESTION
The gastro-splenic omentum connects the left extremity of the stomach with
the spleen, continuing the layers of peritoneum which enclose the stomach.
The gastro-phrenic and phreno-colic ligaments. As the peritoneum passes
from the diaphragm to the stomach it forms a small fold just to the left of the
œsophagus. This is the gastro-phrenic ligament. A stout fold of the membrane
also extends from the diaphragm (opposite the tenth and eleventh ribs) to the
splenic flexure of the colon, and is known as the phreno-colic or costo-colic ligament.
Subperitoneal connective tissue. An elaborate account of this tissue has been
written by Mr. Anderson and Mr. Makins. According to these observers, the
subperitoneal and subpleural fascia are to be regarded as a portion of a wide
system of mesoblastic connective tissue which surrounds the great vessels of the
trunk, accompanying these branches from origin to termination, and extending
mainly in the form of perivascular sheaths to all parts of the body.'
-
The subperitoneal segment of the tissue they divide into two portions: a
parietal layer, closely connected to the wall of the cavity, and visceral lamina
which accompany the branches of the aorta to their distribution.
The parietal layer is developed chiefly in front of the vertebral column, 'from
which point it may be traced as a broad expansion between, and intimately connected
with, the peritoneum on the one hand, and the transversalis, diaphragmatic, iliac,
obturator, and recto-vesical fascia on the other.' It forms a sheath for the large
vessels, and is continuous with the vessels outside the abdomen.
The visceral portion follows the course of the branches of the aorta, and
greatly assists in fixing certain viscera, such as the liver, pancreas, etc., becoming
continuous with their connective tissue tunic. This tissue can be seen passing
between the layers of peritoneum to those organs which are connected to the abdo-
minal wall by duplicatures of peritoneum.
For an account of the evolution of the peritoneum, and an explanation of its
arrangement in the human body, the student is referred to page 1027.
THE ABDOMEN
The abdomen properly consists of that part of the body cavity situated between
the diaphragm and the pelvis. It is bounded above by the diaphragm; below,
by the brim of the true pelvis; behind, by the vertebral column, diaphragm,
quadratus lumborum and psoas muscles, and by the posterior portions of the ilia.
At the sides it is limited by the anterior parts of the ilia and the hinder segments
of the muscles which compose the anterior abdominal wall, viz. the transversalis,
internal oblique, and external oblique. In front, besides these muscles, there are
the two recti and pyramidales muscles. External to the peritoneum the abdomen
is lined by a special layer of fascia.
The abdomen is the largest serous cavity in the body. Its serous membrane is
the peritoneum, which, through its various complicated arrangements, is always
(with one unimportant exception) a closed sac, so that the viscera are in reality
situated outside the enclosure. The principal viscera found in the abdomen are
those connected with digestion and the excretion of urine.
On freely laying open an abdomen from the front, the general form of the space
is seen to be an irregular hexagon, the sides of which are formed as follows-the
upper two by the margins of the costal cartilages with the ensiform cartilage
between; the two lateral sides by the edges of the lateral boundary; and the two
lower by the two ligaments of Poupart which meet at the pubes.
THE ABDOMEN
995
In this irregular hexagon the following organs can be observed without dis-
arranging their normal position (fig. 565). Above, on the right side under the
costal cartilages, can be seen the liver, which extends from the right across the
median line to a point below the left costal cartilages. Below the liver, and lying
to the left side, can be seen the anterior surface of the stomach; from the lower
border of the stomach the omentum extends downwards, and shining through it can
be seen the middle part of the transverse colon. On each side and below the
FIG. 565. THE VISCERA AS SEEN ON FULLY OPENING THE ABDOMEN WITHOUT
DISARRANGEMENT OF THE INTERNAL PARTS. (After Sarazin.)

LIVER
Falciform
ligament
of liver.
TRANSVERSE
COLON
CÆCUM
BLADDER
DIAPHRAGM
GREAT OMENTUM
SMALL
INTESTINE
SIGMOID
FLEXURE
irregularly folded omentum are exposed the coils of the small intestine; in the
right iliac fossa a part of the cæcum appears; and in the left iliac fossa a coil of
the sigmoid flexure is usually evident.
To the left of the stomach and under cover of the lower ribs of the left side
the edge of the spleen may possibly be observed; and just below the edge of the
liver, and about the level of the tip of the ninth rib, the gall bladder may be seen.
The dome of the bladder may be noticed just behind the symphysis pubis and in
the median line. The disposition of the viscera in the foetus is shown in fig. 578.
3s2

996
THE ORGANS OF DIGESTION
THE STOMACH
General description.-The stomach is situated in the upper part of the abdo-
minal cavity and to the left side. Above it are the liver and diaphragm, while
below is the transverse colon. It is somewhat pyriform in outline, with the small
end of the figure twisted upward. Its length is about twelve inches, and its width
four inches. It weighs four ounces and a half.
There are two orifices, two borders, and two surfaces to be noticed. The left,
splenic, or cardiac end of the viscus is much expanded, and forms the great cul-de-
sac or fundus. At the right or pyloric end there is another slighter expansion,
called the antrum pylori or small cul-de-sac (fig. 566).
The cardiac orifice, by which the oesophagus opens into the stomach, is situated
about three inches from the left extremity, owing to the bulging to the left of the
great cul-de-sac. The pyloric orifice, or pylorus, is situated to the extreme right,
and is more anterior in position than the cardiac orifice.
The pylorus is produced by a thickening of the intestinal walls between the
FIG. 566.-POSTERIOR SURFACE OF THE STOMACH.
CARDIAC ORIFICE
FUNDUS
PYLORUS
ANTRUM PYLORI
duodenum and stomach.
The circular muscular fibres which surround the stomach
are here thickened into a strong ring, thus forming a sphincter which can be felt
from the outside. The longitudinal fibres pass over the circular fibres, and are not
generally supposed to take part in the thickening. The mucous membrane is
pushed in by the muscular ring and also thickened. The pyloric opening will
about admit a sixpence. It is the narrowest part of the digestive canal. There
is no such special sphincter apparatus at the cardiac end of the stomach, the
œsophagus passing directly into its walls, becoming wider as it does so.
The two borders are situated above and below, and run between the two
orifices. The upper is known as the lesser curvature, and is about three or four
inches long; it is concave along its whole length, except near the pylorus, where it
takes part in the antrum pylori (fig. 567). The lower border is called the greater
curvature, and is convex except near the right extremity just before the formation
of the antrum pylori, where there is a slight depression.
The two surfaces lie between the two borders. They are of equal extent, and
are named the anterior and posterior surfaces.

THE STOMACH
997
Relations to surrounding parts.-The degree of obliquity of the stomach in its
relation to the long axis of the body has been a disputed point, the majority of
authorities holding that it lies slightly obliquely from left to right; while a few
(Luschka and Lesshaft) maintain that its direction is vertical. In an early period
of development the organ is certainly vertical, and in rare instances this position
may be maintained throughout life. As a rule, however, the organ is placed
obliquely, and lies in the left hypochondriac and epigastric regions (figs. 578, 582,
and 583).
The cardiac end, or fundus, reaches as high as the level of the sixth chondro-
sternal articulation, being a little above and behind the heart apex. The cardiac
orifice is opposite the seventh left costal cartilage, and is about one inch from the
sternum. Behind, it is about on the level of the ninth thoracic spine. The pylorus
is on a lower level and nearer the surface than the cardiac end, and is opposite a
point to the right of the middle line two to three inches below the sterno-xiphoid
articulation, on the level of a line drawn between the bony ends of the seventh
ribs (fig. 582). Behind, it is on a level with the twelfth thoracic spine (fig. 583).
FIG. 567.-ANTERIOR SURFACE OF THE STOMACH.

PYLORUS
CARDIAC ORIFICE
ANTRUM PYLORI
SER CURVATURE
FUNDUS
GREATER CURVATURE
The posterior surface of the stomach looks backwards and downwards, lying on
the transverse meso-colon, spleen, splenic artery, pancreas, left kidney and supra-
renal capsule, and great abdominal vessels (figs. 586, 590).
ABOVE.
Liver, small omentum, diaphragm.
IN FRONT.
(From left to right.)
Diaphragm, abdominal wall, liver.
GENERAL RELATIONS
OF THE
STOMACH
BEHIND.
Transverse meso-colon, pancreas
crura, solar plexus, great
vessels, spleen, left kidney, and
capsule.
BELOW.
Great omentum, transverse colon, gastro-splenic omentum.
The anterior surface looks upwards and forwards. Its relations are of import-
ance in connection with the operation of gastrostomy. A certain portion of this
998
THE ORGANS OF DIGESTION
surface comes into immediate contact with the abdominal wall; this portion is
triangular in shape, is bounded on the right by the edge of the liver, and on the
left by the cartilages of the eighth and ninth ribs; and below by a horizontal
line passing between the tips of the tenth costal cartilages (fig. 582). Besides the
abdominal wall, this surface is covered by the diaphragm and the under surface of
the liver (fig. 590).
Relations to the peritoneum.-The stomach is covered by peritoneum in its whole
extent, except immediately along the curvatures and upon a small triangular space
at the back of the cardiac orifice. It is enclosed between two layers. These two
layers at its upper border or lesser curvature come together to form the lesser
omentum, and at the lower border or greater curvature extend downwards, to form
the great omentum (figs. 562, 563). At the left of the oesophagus the two layers
pass to the diaphragm, forming the gastro-phrenic ligament; and at the fundus
they pass on to the spleen, forming the gastro-splenic omentum.
FIG. 568.-MUSCULAR COAT OF THE STOMACH. (Luschka.)

LONGITUDINAL LAYER
CIRCULAR LAYER
Alteration of position.-As the stomach becomes distended it undergoes some
alteration in position. The greater curvature is elevated and carried forwards,
the anterior surface is directed upwards, and the posterior downwards, and the
pylorus passes some inches to the right. This rotation about its long axis is
influenced by the fixity of the lesser curvature of the organ.
Structure. The walls of the stomach consist of four coats-serous, muscular,
submucous, and mucous.
The external serous coat is formed by the peritoneum, and has to the naked
eye the usual shiny appearance of that membrane.
The muscular coat consists of three layers:-
A longitudinal layer externally, which is continued from similar fibres on the
œsophagus, and is thickest along the curvatures, more particularly the lesser. At
the pylorus the fibres are more regularly placed round that orifice (fig. 568).
A circular layer, which regularly surrounds the whole stomach, and becomes
much thicker at the pyloric end where it forms the sphincter. These circular
fibres are arranged perpendicularly to the long axis of the stomach (fig. 569).
An oblique layer, continuous with the circular fibres of the oesophagus. They
THE STOMACH
999
pass to the left of the oesophagus towards the great curvature. They unite finally
with the circular fibres (fig. 569).
The submucous coat is made up of areolar tissue, in which the blood-vessels
break up.
The mucous or internal coat is pink in colour and soft to the touch, and when
the stomach is not distended has a rugose appearance. It is covered with columnar
epithelium, and with a lens shows the openings of numerous glands. A thin
layer of muscular tissue--the muscularis mucosa-supports the mucous membrane
externally.
Nerves. The nerves of the stomach are the right and left pneumogastric,
the right nerve passing over the posterior surface, and the left over the anterior.
The organ is also connected with the sympathetic system by means of the solar
plexus.
FIG. 569.-MUSCULAR COAT OF THE STOMACH. (Luschka.)
OBLIQUE LAYER

CIRCULAR LAYER
Blood-supply. The stomach receives its blood-supply from many branches.
From the coeliac axis there is the gastric artery, which runs along the lesser curve
from left to right, anastomosing with the pyloric branch of the hepatic. Along
the greater curve run the right and left gastro-epiploic arteries anastomosing at the
middle of the border, the left being a branch of the splenic, the right a branch of
the hepatic through the gastro-duodenal artery. The stomach also receives branches
from the splenic (vasa brevia) at the fundus.
The blood of the stomach is returned into the portal vein. The coronary vein
and pyloric vein open separately into the portal vein; the right gastro-epiploic vein
opens into the superior mesenteric, the left into the splenic.
Lymphatics. There is a set of glands lying along the greater and the lesser
curvatures, and others at the pyloric and cardiac ends. These are entered by
lymphatic vessels beginning in the mucous membrane.


1000
THE ORGANS OF DIGESTION
THE INTESTINES
THE SMALL INTESTINE
The small intestine is that part of the intestinal canal which lies between the
pylorus and the ileo-cæcal valve. It is conveniently divided into three portions:
the duodenum, jejunum, and ileum. It is of the average length in the adult male
(between the ages of twenty and fifty) of twenty-two feet six inches. In the
female it is longer, the average length being twenty-three feet four inches. The
length is independent, in the adult at least, of age, height, or weight. The length
may vary in the male from thirty-one feet ten inches to fifteen feet six inches. In
the female, from twenty-nine feet four inches to nineteen feet ten inches.
With the exception of the duodenum, the small intestine lies for the most part
inside the more fixed portions of the large intestine (figs. 565, 578). It is also, with
the exception of the duodenum, connected to the posterior abdominal wall by a pro-
cess of peritoneum, the mesentery. This broad membrane is seen to extend from
above downwards, and from left to right from the end of the duodenum above to
the ileo-cæcal valve below, enclosing the jejunum and ileum along the whole of
their extent (figs. 561, 563, and 599).
The duodenum-the first portion of the small intestine-is, unlike the other parts
of that bowel, very definite in position and extent. It is that part which is not
contained by the mesentery. It is formed from the end of the embryonic fore-gut,
and its peculiar position behind the transverse colon is due to the rotation from
left to right of the intestine in the foetus (page 1032). It is the most fixed as
well as the widest part of the small intestine. It measures one and a half to two
inches in diameter, and is about ten inches long. It has been compared in general
shape to a horseshoe, though not very aptly, as the one side is so much longer than
the other. It is arranged in a curved manner round the pancreas, and readily lends
itself to a division into four parts (fig. 577).
The first part-the superior, or ascending-is hardly two inches long. Begin-
ning at the pylorus, and passing upwards and backwards to the right, it ends at the
neck of the gall-bladder. It is the most movable of the four portions. It is covered
by the two layers of peritoneum which are continued from the stomach, and by
these it is completely surrounded. Above it are found the liver (quadrate lobe)
and gall bladder. The gut itself forms the lower boundary of the foramen of
Winslow. Below it is the pancreas; and behind are the common bile-duct and
hepatic vessels.
The second part-the descending portion-not quite three inches long, extends
from the neck of the gall bladder to the second or third lumbar vertebra, a
short bend marking the separation between the first and second parts.
This
part is covered by peritoneum in front only, the membrane being derived from a
continuation of the superior layer of the transverse meso-colon (fig. 570).
It is more fixed than the first portion. It is in relation in front with the
transverse colon and meso-colon. On its left side is the pancreas (fig. 577), and the
common bile-duct a little more posteriorly. The loop formed by the pancreatico-
duodenal arteries runs also along the left margin of this part of the bowel.
Behind lie the right kidney and the renal vessels and vena cava (fig. 590).
Some of the muscular fibres of this part of the duodenum are said to be con-
tinuous with the lobules of the pancreas. Into this segment of the bowel, at its
inner and back part and some four inches from the pylorus the common bile-duct
and pancreatic duct enter (figs. 571, 586, and 587).

THE SMALL INTESTINE
1001
The third part, or transverse portion, is the longest, being about five inches
long. It extends from the body of the second or third lumbar vertebra on the
right side, and passes obliquely across the spine to the upper part of the left side,
ascending a little on its way. In front of the third part of the duodenum is found
the lower layer of the transverse meso-colon. The superior mesenteric vessels cross
FIG. 570.-THE DUODENUM FROM IN FRONT.
SUPERIOR LAYER OF TRANSVERSE MESO-COLON

SECOND PART OF
DUODENUM
GOLON
JEJUNUM
PANCREAS
FOURTH PART OF DUODENUM
INFERIOR LAYER OF TRANSVERSE MESO-COLON
THIRD PART OF DUODENUM
SUPERIOR MESENTERIC VESSELS
this part of the bowel, running between it and the pancreas to reach the mesentery
(fig. 570). Along the upper border runs the inferior pancreatico-duodenal artery.
The gut is in relation above with the pancreas and superior mesenteric artery.
Behind are the vena cava, aorta, and crura of the diaphragm (figs. 571, 577). It is
FIG. 571.-THE DUODENUM FROM BEHIND.
Portal vein

PANCREAS
JODENUM. DESCEND. PART
COMMON
BILE DUCT
FOURTH PART OF DUODENUM
HEAD OF PANCREAS
the most fixed portion of the duodenum, and is covered in front only by peritoneum.
The fourth part of the duodenum, or second ascending portion, ascends vertically
by the left side of the spine. This vertical portion--which is covered entirely in
front and partly at the sides by peritoneum-is at least an inch in length (figs. 570,
571, and 572). The end of the duodenum is very firmly fixed in its place by the

1002
THE ORGANS OF DIGESTION
musculus suspensorius duodeni. This name has been given to a fibrous band that
contains, according to Treitz, some plain muscular fibres, and that descends to the
vertical part of the duodenum from the left crus of the diaphragm and the tissues
about the cœliac axis.
Mr. Lockwood points out that this band is continued on, after being inserted
into the duodenum, between the layers of the mesentery. He suggests the name
of the suspensory muscle of the duodenum and mesentery,' and says, 'together
with the other constituents of the root of the mesentery, it forms a band of con-
siderable strength, sufficient not only to support the weight of the intestines and
mesentery, but also to resist the pressure of the descent of the diaphragm.'
In connection with the termination of the duodenum may be mentioned the
fossa duodeno-jejunalis. It is formed as a pouch behind a fold of peritoneum. This
fold runs from the parietal peritoneum, just to the left of the terminal or fourth
part of the duodenum, and is attached in a vertical line to the anterior surface of
this portion of the bowel. It is of interest as being the seat of origin of a retro-
peritoneal hernia.
6
The fold forming the fossa is the remains of the duodenal fold,' modified by
FIG. 572. THE FOSSA DUODENO-JEJUNALIS. (Treves.)
TRANSVERSE COLON
THE FOSSA-
THE DUODENAL
FOLD
TRANS. MESO:COLON
JEJUNUM
DESC.
COLON
Inferior
mesenteric vein
growth and displaced by the process of unequal development in the intestinal
canal (page 1040, and figs. 605, 606). The pocket, or fossa, is of triangular
outline, with the base or orifice upwards. Its apex extends below the last bend
of the duodenum (fig. 572). The capacity of the fossa varies. In well-marked
specimens it will lodge the thumb up to the first joint. It is actually occupied
by the duodeno-jejunal junction or bend. Out of one hundred bodies examined I
found this fossa in forty-eight examples.
Jejunum and ileum.-There is no unvarying method in the arrangement of the
individual coils of the small intestine.
In the majority of adult bodies the small intestine is disposed in an irregularly
curved manner from left to right. The gut, starting from the duodenum, will first
occupy the contiguous parts of the left side of the epigastric and umbilical regions;
the coils then fill some part of the left hypochondriac and lumbar regions; they
now commonly descend into the pelvis, reappearing in the left iliac quarter, and
then occupy, in order, the hypogastric, lower umbilical, right lumbar, and right
iliac regions. Before reaching the last situation they commonly descend again
into the pelvis.
THE SMALL INTESTINE
1003
The
In many instances no kind of methodical arrangement is apparent.
coils of small intestine most usually found in the pelvis belong to the terminal part
of the ileum, and to that part of the intestine that has the longest mesentery-
the part, namely, that extends between two points, respectively six and eleven feet
from the end of the duodenum. In five out of one hundred cases examined, the
coils were arranged in an exactly reverse manner to that just described.
The jejunum (jejunus, empty).-The jejunum is the name given to the upper
two-fifths of the small intestine below the duodenum.
The term ileum (elev to twist) is applied to the last three-fifths of the bowel.
The ileum ends at the ileo-cæcal valve. The coils formed by the jejunum and
ileum are very movable, are completely invested by peritoneum, and are supported
and attached to the posterior parietes by the extensive membrane known as the
mesentery.
The intestine alters gradually in character from above downwards. If a
segment from the middle of the jejunum be compared with a portion of the middle
ileum, the following differences would be noted. The diameter of the jejunum is
about an inch and a half, that of the ileum one and a quarter. The jejunum
has thicker walls, is more vascular, and is provided with a more complex mucous
membrane.
Meckel's diverticulum. From one to three feet from the end of the ileum is
sometimes seen a diverticulum, or blind tube or cord, coming off from the free
margin of the bowel. This is Meckel's diverticulum, and represents the remains of
the vitello-intestinal duct (page 1030).
The mesentery. The mesentery extends from the end of the duodenum to the
ileo-cæcal junction. It envelopes and supports the ileum and jejunum. Its upper
or right layer is continuous with the under layer of the transverse meso-colon and
with the peritoneum that invests the ascending colon. Its lower or left layer
joins with the serous membrane that encloses the descending colon and that forms
the sigmoid mesentery (fig. 561).
The point at which the mesentery is attached above is on a level with the lower
border of the pancreas and just to the left of the vertebral bodies. From this
point the insertion of the mesentery follows an oblique line that runs downwards
and to the right, crossing the great vessels, and ending in some part of the iliac
fossa (fig. 599). In the absence of an ascending meso-colon (the normal condition)
the peritoneum that covers the cæcum is reflected from the hinder surface of that
part of the bowel on to the posterior parietes; at this reflexion the mesentery
ends. If an ascending meso-colon exists, the mesentery terminates by joining it.
The parietal attachment of the mesentery measures, as a rule, about six inches
(fig. 599). The length of the mesentery from the spine to the intestine varies in
different parts of the canal; its average length may be taken as between eight and
nine inches. It soon attains its full length, and within one foot of the end of the
duodenum is already six inches in length.
The ordinary type of mesentery conforms to the figure of half a circle, but the
membrane is liable to considerable variation. It is not uncommon to find the
mesentery maintaining a considerable length up nearly to the end of the ileum.
Structure of the small intestine. Its coats are four in number, viz. serous,
muscular, areolar, and mucous. The intestine receives its serous covering from
the peritoneum, and, with the exception of certain parts of the duodenum which
have been described, it is covered entirely by it, save only where the layers leave it
behind to form the mesentery. The line of attachment of the mesentery marks the
attached border of the small intestine.
The muscular coat is divided into an external longitudinal layer and an
internal circular, the circular being the thicker of the two. Both layers are uniform
around the bowel.


1004
THE ORGANS OF DIGESTION
The areolar or submucous coat consists of areolar tissue connecting the muscular
and mucous tunics. A thin layer of muscular tissue separates the mucous membrane
from the areolar coat (muscularis mucosa).
The mucous coat, thicker at the upper part than the lower part, is lined
throughout with columnar epithelium and is very vascular. The whole surface is
covered with minute processes called villi; these give the membrane a finely
flocculent appearance, which has been compared to the pile of velvet. They are
largest and most numerous in the duodenum and jejunum, and become gradually
shorter, smaller, and fewer on the ileum. Besides the villi are certain large folds
or valvular flaps: these are the valvula conniventes. They are permanent cres-
centic folds of mucous membrane set transversely to the long axis of the intestine,
which extend from one half to two-thirds of the distance round the lumen (fig. 573).
The largest are more than two inches long, and about one-third of an inch wide.
They do not exist at the beginning of the duodenum. They are very large
just below the entrance of the bile duct, and remain conspicuous until the middle
of the jejunum is reached. They then become smaller, and gradually disappear
at the lower part of the ileum.
FIG. 573.-PORTION OF THE SMALL INTESTINE, LAID OPEN TO SHOW THE
VALVULE CONNIVENTES. (Brinton.)
Scattered over the whole of the mucous membrane of the small intestine are
numerous minute soft rounded bodies. These are the so-called solitary glands.
Certain patches, called Peyer's patches, are found in the lower ileum. They
are oval, are from one half to three inches in length, and about one inch in
breadth, and are placed on the long axis of the bowel along a line most remote
from the mesentery. They are made up of an aggregation of solitary glands.
A number of closely set tubular glands, called Brunner's glands, may be exposed
by dissection in the first part of the duodenum.
Blood-supply of the small intestine. The small intestine receives its blood
from the superior mesenteric artery, and a branch coming indirectly from the
hepatic, the superior pancreatico-duodenal. The superior mesenteric runs between
the layers of the mesentery, and gives off about twelve or fifteen branches, running
downwards and to the left (vasa intestini tenuis), which break up and form a series
of arches, finally encircling the intestine as small branches. It also gives off a
small branch at the beginning, the inferior pancreatico-duodenal, which, with the
superior pancreatico-duodenal, forms an arch, which lies in the concavity of the
duodenum and supplies it. The blood is returned by means of the superior
mesenteric vein, which with the splenic vein forms the portal (fig. 574).

THE SMALL INTESTINE
1005
The lymphatics form a continuous series, which is divided into two sets-viz.
that of the mucous membrane, and that of the muscular coat. The lymph vessels
of both sets form a copious plexus, and end in the mesenteric lacteals (fig. 574).
The nerves.-The small intestine is supplied by means of the superior
FIG. 574.-VESSELS OF THE SMALL INTESTINE.

LACTEALS
Veins
mesenteric plexus, which is continuous with the lower part of the solar plexus.
The branches follow the blood-vessels, and finally form two plexuses: one (Auer-
bach's) which lies between the muscular coats; and another (Meissner's) in the
submucous coat.

then
THE LARGE INTESTINE
The large intestine is that part of the alimentary canal which extends between
the ileum and the anus. It is divided into the following parts:-Cæcum, ascending,
transverse, and descending colon, sigmoid flexure, and rectum. It is so arranged
as to surround the small intestine, making a circuit round the abdominal cavity
from right to left (fig. 565). The cacum lies in the right iliac fossa; thence the
colon passes vertically upwards on the right side (ascending colon) until the liver
is reached. Here it forms a more or less rectangular bend (hepatic flexure), and
passes transversely across the belly (transverse colon) below the stomach. It
then reaches the splenic area, where it makes a second sharp bend (splenic flexure),
and, passing vertically downwards on the left side (descending colon), reaches the
left iliac fossa. At this point it forms the loop of the sigmoid flexure, and finally
passes through the pelvis as the rectum (fig. 577). It is much larger in diameter
than the small intestine, and has not the same general convoluted arrangement.
Leaving out of consideration the dilated portion of the rectum, it is wider at the
beginning than at the end. It varies in width at different parts from two and a
half to one and a quarter inches. The length from the root of the appendix or tip
of the cæcum to the point where the meso-rectum ends is, in the male, about four
feet eight inches; and in the female, about four feet six inches.
The extremes found in a number of cases were, for both sexes respectively, six
feet six inches, and three feet three inches.
The large intestine, in all parts except the rectum, has a peculiar arrangement
of its walls, which gives it a very different appearance to the small intestine. It

1006
THE ORGANS OF DIGESTION
is sacculated, and the sacculation is produced by the gut having to adapt its length
to three shorter muscular bands which run the course of the intestine. These
bands are really the longitudinal fibres of the muscular wall, which are chiefly
collected at three parts (fig. 575). One band is situated posteriorly on the attached
border, another runs anteriorly, and the third is situated on the inner side of the
ascending and descending colon, and on the lower border of the transverse colon.
All these bands start at the vermiform appendix, and are lost on the rectum.
Along the whole length of the large intestine, except the lower part of the rectum,
are certain small appendages (appendices epiploica), seen mostly along the line of
the inner muscular band. They are pouches of peritoneum containing fat.
The cæcum, or caput coli.-The cæcum is a cul-de-sac forming the first part of
the large intestine. It is defined as that part of the colon which is situated below
the entrance of the ileum. Its breadth is about three inches, and its length about
two and a half inches.
It lies in the right iliac fossa, and is usually situated upon the psoas muscle,
and so placed that its apex or lowest point is just projecting beyond the inner border
of that muscle (figs. 565, 577). It is entirely enveloped in peritoneum, and is
free in the abdominal cavity. The apex of the cæcum usually corresponds with a
point a little to the inner side of the middle of Poupart's ligament. Less frequently
A
FIG. 575. THE FOUR TYPES OF CECUM. (Treves.)
B
୯
D
ELLO
the cæcum will be found to be in relation with the iliacus muscle only; or the bulk
of the caput will lie upon that muscle, while the apex rests upon the psoas. In a
number of cases the cæcum is entirely clear of both psoas and iliacus muscles, and
hangs over the pelvic brim, or is lodged entirely within the pelvic cavity. Some
part of the cæcum may pass even to the left of the median line of the body.
This part of the colon is liable to considerable variation.
Its variations may be described under four types :-
1. The fœtal type is conical in shape, the appendix arising from the apex.
This process is a continuation of the long axis of the colon. The three muscular
bands which meet at the appendix are nearly at equal distances apart (fig. 575, A).
2. The second form is more quadrilateral in shape than the last; the three
bands retain their relative positions; the appendix appears between two bulging
sacculi, instead of at the summit of a cone (fig. 575, B).
3. In the third type, that part of the caput coli that lies to the right side of the
anterior band grows out of proportion to that part to the left of the band. The
anterior wall becomes more developed than the posterior, so that the apex is turned
so much to the left and posteriorly, that it nearly meets the ileo-cæcal junction.
A false apex is formed by the highly developed part to the right of the anterior
band. This is the usual cæcum found (fig. 575, c).
4. In the fourth type, the development of the part to the right of the anterior
THE LARGE INTESTINE
1007
band is excessive, while the segment to the left of the band has atrophied. In this
form the anterior band runs to the inferior angle of junction of the ileum with the
cæcum. The root of the appendix is posterior to that angle. There is no trace of
the original apex, and the appendix appears to spring almost from the ileo-cæcal
junction (fig. 575, D).
Other variations.-The cæcum may vary in its general development. It is
sometimes small and insignificant, in other cases it reaches a large size. It may
be so rotated that the ileum passes behind the colon and opens on the right side.
The posterior part has been seen much more developed than the anterior, so that
the ileum has entered from the front, and the appendix has come off from the
anterior wall. The cæcum may remain undescended, and be found just under the
liver or in the vicinity of the umbilicus. The cæcum and colon may be suspended
by a mesentery common to the whole intestinal canal. In such cases the primitive
condition of the peritoneal fold which supports the small and large intestine is
permanently retained (page 1034).
The vermiform appendix.-Attached to what is really the original apex of the
cæcum is a narrow blind tube: this is the vermiform appendix. It usually comes
off close to the ileo-cæcal valve on the inner and posterior side of the bowel, though
occasionally it forms the true apex of the cæcum. In the adult the average length
is four inches, the extremes being one inch and six inches. In the majority of
instances the appendix is much twisted upon itself. Its usual position is behind
the end of the ileum and its mesentery, and pointing in the direction of the spleen.
It may occasionally ascend vertically behind the cæcum.
It has a definite mesentery, which comes off from the left layer of the mesentery
of the ileum. Its origin from this layer is along a straight line which is situated
at a short distance from the intestine, and which is not quite parallel with the
margin of the bowel. In general outline the mesentery is triangular. In the
adult it does not extend along the whole length of the tube. It is, in fact, too
short for the appendix, and it is this that accounts for the twisted condition of the
little process. Along the free margin of the mesentery runs a branch of the ileo-
colic artery.
Ileo-cæcal fossa.-About the cæcum, and especially in the vicinity of the ileo-
cæcal junction, are certain fossæ collectively known as the ileo-cæcal. Two only
appear to be fairly constant. The first, the superior ileo-cæcal, is formed by the
passage across the junction of the cæcum and ileum of a branch of the ileo-colic
artery, which produces a fold of peritoneum limiting a pouch. It is on the anterior
aspect of the bowel, and the pouch opens downwards.
The second fossa is not quite so simple. If the cæcum be turned upwards so
as to expose its posterior surface as it lies in situ, and if the appendix be drawn down
so as to put its mesentery on the stretch, a peculiar fold will be found to join that
mesentery. This fold arises from that border of the ileum which is most remote
from the insertion of its mesentery. It then passes over the ileo-cæcal junction on
its inferior aspect, is adherent to the cæcum, and finally joins the surface of the
mesentery of the appendix. This fold is peculiar in the absence of any visible
vessels.
Between it and the appendix there is an almost constant fossa, the
inferior ileo-cæcal. It is large, admitting two fingers. It opens outwards, and is
bounded on one side by the small intestine, and on the other by the cæcum.
The ileo-cæcal valve. The ileo-cæcal valve, which is situated at the entrance
of the ileum into the large intestine at the upper border of the cæcum, is found on
the inner side and towards the posterior aspect of the intestine. The ileum passes
from below upwards and towards the right, and terminates with a considerable
degree of obliquity. The valve is formed by two semilunar folds projecting into
the large intestine, set nearly transversely, the lower being a little oblique. The
opening between them takes the form of a narrow slit, rounded in front but narrow


1008
THE ORGANS OF DIGESTION
behind. At the ends of the slit the valves unite and are prolonged at either end as
a ridge partially surrounding the intestine (fræna). Villi cover that surface of the
folds looking towards the ileum. The surface towards the large intestine is free
from villi. In the formation of this valve the longitudinal muscular fibres pass
across from the ileum to the large intestine without dipping down between the two
layers of each fold. The circular muscular fibres, on the other hand, are contained
between the layer of the mucous membrane and submucous tissue which form them.
The colon. In the adult the ascending and the descending parts of the colon are
placed vertically, while the direction of the transverse colon is practically horizontal.
The average length in the adult of the ascending colon (as measured from the tip
of the cæcum to the hepatic flexure) is eight inches, and of the descending colon
(as measured from the splenic bend to the commencement of the sigmoid loop) is
eight and a half inches. The descending colon is the part of the large bowel that
is least liable to variation. It is the only part of the gut except the duodenum that
retains its original position as a portion of the great primary vertical loop. The
FIG. 576.-SECTION OF THE ASCENDING COLON. (Allen Thomson.)
Crescentic ridge of mucous
membrane which divides the sacculi
Longitudinal muscle
Serous coat-
Anterior band-
Mucous membrane-
Crescentic ridge of
mucous membrane
Circular muscle
Appendix epiploica
Posterior band
Mucous membrane
Crescentic ridge of
mucous membrane
Serous coat
Inner band Circular muscle
transverse colon, on the other hand, is liable to considerable variation in length,
position, and arrangement. Its average length is twenty inches in the adult. It
has been found to vary in adults from twelve to thirty-three inches.
The ascending colon. The ascending colon extends from the cæcum to the
inferior surface of the liver close to the gall bladder, forming there the hepatic flexure.
It is covered by peritoneum in front and at the side, but in a certain proportion of
cases (twenty-six per cent in one hundred dissections) this part of the large intestine
is connected with the posterior wall of the abdomen by a meso-colon, that is to say,
it is quite surrounded by peritoneum. Connected with the ascending colon is
sometimes found a fold of peritoneum, extending from the right side of the gut to
the parietes at a little above the level of the highest part of the iliac crest. It
forms a shelf upon which rests the extreme right margin of the liver. It might be
called the sustentaculum hepatis.
The ascending colon is in relation behind with the right kidney, second portion
of the duodenum, and quadratus lumborum. In front are some of the coils of the
ileum (fig. 577).

THE COLON
1009
The transverse colon.-The transverse colon, smaller in diameter than the
ascending, extends from the under surface of the liver to the spleen. Being
longer than a straight line between these two points, it has to describe an arch
with its convexity forwards; it also bends a little downwards. It crosses through
the umbilical region from the right hypochondrium to the left hypochondrium
(fig. 565).
In the majority of cases the superficial part of the colic arch-as seen before
the viscera are disturbed-is either in whole or in greater part above a straight line
drawn transversely across the body between the highest points of the iliac crest.
In the proportion of one to four it lies, in whole or in greater part, below this line
(fig. 582).
Certain remarkable bends are sometimes formed by this part of the bowel.
The bending is always in the same direction, namely, downwards, and is usually
abrupt and angular. The apex of the V or U-shaped bend thus formed may
reach the pubes. This bend appears to be due to two distinct causes: namely,
long continued distension on the one hand, and to congenital malformation on the
other.
The transverse colon is in relation above with the liver and gall bladder,
the stomach, and at its left extremity with the spleen. The third portion of the
duodenum passes behind it. Below are the coils of the small intestine. It is
surrounded with peritoneum, being connected with the posterior abdominal wall by
a meso-colon.
The descending colon extends from the spleen to the sigmoid flexure. It is
more movable than the ascending colon. It is also narrower. At its beginning
it is connected with the diaphragm, at a level with the tenth and eleventh ribs, by a
fold of peritoneum, the costo-colic ligament (or sustentaculum lienis, from the fact
that it supports the spleen). The bend between the transverse colon and descending
colon is called the splenic flexure. The descending colon is situated in the left
hypochondriac and lumbar regions (fig. 591). Its relations to the peritoneum are
the same as obtain with the ascending colon, that is, it is covered in front and on
the sides. A meso-colon is met with oftener on this side than on the right. In
one hundred dissections it was found thirty-six times. The descending colon is
covered in front by the small intestine; behind, are part of the diaphragm, the left
kidney, and the quadratus lumborum muscle (fig. 577).
The sigmoid flexure and rectum.-The segment of gut termed the sigmoid
flexure, and the so-called first part of the rectum, form together a single simple
loop that cannot be divided into parts. This loop begins where the descending
colon ends, viz. in the left iliac fossa, and ends at the commencement of the
so-called second piece of the rectum-at the spot, where the meso-rectum ceases,
opposite about the third piece of the sacrum in the median line. The loop when
unfolded describes a figure that may be compared to the capital omega.
average length of this sigmoid or omega loop is seventeen inches and a half. The
normal position of the loop is not in the left iliac fossa, but wholly in the pelvis.
The most common disposition of it may be now described.
The
The descending colon ends just at the outer border of the psoas. The gut here
suddenly changes its direction, and the sigmoid or omega loop begins (figs. 565,
577). The bowel crosses the muscle at right angles and about midway between the
lumbo-sacral eminence and Poupart's ligament. It now descends vertically along
the left pelvic wall, and may at once reach the pelvic floor. It then passes more
or less horizontally and transversely across the pelvis from left to right, and
commonly comes into contact with the right pelvic wall. At this point it is
bent upon itself, and, passing once more towards the left, reaches the middle line
and descends to the anus.
It will lie therefore in more or less direct contact
with the bladder and uterus, and may possibly touch the cæcum. It is very closely
3 T

1010
THE ORGANS OF DIGESTION
related with the coils of small gut that occupy the pelvis, and by these coils the
loop is usually hidden.
The sigmoid or omega loop is attached to the abdominal and pelvic wall by a
meso-colon, so that it is quite surrounded by peritoneum. The line of attachment
of this meso-colon is as follows. It crosses the psoas at a right angle, and then
takes a slight curve upwards so as to pass over the iliac vessels at or about their
FIG. 577.-VIEW OF THE DEEPER ABDOMINAL VISCERA. (Rüdinger.)
Superior vena cava-
L
Aorta
THORACIC DUCT-
LEFT BRONCHUS
Inferior vena cava-
CESOPHAGUS
-SPLEEN
PANCREAS
KIDNEY
-KIDNEY
DUODENUM
DESCENDING COLON
ASCENDING COLON-
SIGMOID FLEXURE
BLADDER
bifurcation. The curve ends at a point either just to the inner side of the psoas
muscle, or between the psoas and the middle line, or, as is most frequently the case,
just over the bifurcation of the vessels. From this point the line of attachment
proceeds vertically down, taking at first a slight curve to the right. Its course is
to the left of the middle line, while its ending will be upon that line, about the
third piece of the sacrum. The sigmoid meso-colon measures from one and a
quarter to three and a half inches in width-i.e. from the parietes to the bowel.

THE RECTUM AND ANUS
1011
When a descending meso-colon exists it joins that of the loop, and the line of
attachment is then, as a rule, directed obliquely across the psoas and the lower end
of the kidney, while beyond the pelvic brim the attachment is as above described.
There is often no meso-colon over the psoas, the gut being adherent to that
muscle.
In connection with the sigmoid meso-colon is often found a fossa or pouch of
peritoneum, known as the intersigmoid fossa. The pouch is formed by the layers
of the meso-colon, and is produced by the
over the bifurcation of the iliac vessels.
opening looks downwards and to the left.
one and a half inch, and is the seat of the sigmoid hernia.
sigmoid artery. It is generally found
The pouch is funnel-shaped, and the
The fossa varies in depth from one to
The rectum. The rectum has been described as divided into three portions.
Such division is quite arbitrary, and is inconvenient. What is usually described
as the first portion has, in the account just given, been included with the sigmoid
flexure.
The two remaining portions of the intestine extend from the middle of the
third piece of the sacrum to the anus.
It would be well if the term rectum were to be limited to that part of the
bowel which is below the level of the third segment of the sacrum, and which is
free of any meso-colon. This portion of bowel-the rectum proper-may be
divided into two portions. The first portion extends from the third piece of the
sacrum to the tip of the coccyx.
This portion, about three and a half inches long, is only covered by peritoneum
above, and then only over the anterior surface. Behind, it is in relation with the
sacrum and coccyx. In front it is in relation with the trigone of the bladder, the
vesiculæ seminales, and under surface of the prostate. In the female the anterior
surface is in relation with the vagina and the cervix uteri.
The peritoneum is reflected from the rectum to the bladder in the male, and
the vagina in the female (recto-vesical or recto-vaginal pouch).
This pouch
extends in the male to within about three inches of the anus. On the posterior
surface of the gut there is no peritoneum below a point five inches from the anus.
The second portion (or what used to be called the third portion) extends from
the tip of the coccyx to the anus; it is about an inch and a half long. It differs
from the first portion in the direction of its curve: while that follows the curve of
the sacrum and coccyx, this portion turns backwards and downwards. It is not
connected with the peritoneum. It is surrounded, after leaving the prostate, by the
internal sphincter, while the levator ani is attached to its side. At its end the
external sphincter is situated; in front is the triangular ligament of the perinæum.
Just above the anus the rectum is much dilated.
The anus.-The anus is the aperture by which the intestine opens externally.
During life it is contracted by the sphincters, so as to give the skin around a
wrinkled appearance. Round the lower part of the rectum and anus certain
muscles that are connected with its proper function are situated. They are the
internal sphincter, the levator ani, and the external sphincter. The levator ani and
external sphincter will be found described in another part.
The internal sphincter is a thickening of the circular fibres of the intestine,
situated round the rectum about an inch above the anus, and extending over half
an inch of the intestine. It forms a complete muscular ring. It is two lines thick,
and is paler than the external sphincter.
The rectum differs from the rest of the colon in presenting perfectly smooth
walls marked by no sacculi, by no longitudinal muscular bands, and by no appen-
dices. The mucous membrane of the rectum is thicker than that of the rest of the
large intestine. Certain folds, chiefly longitudinal in direction, are seen in the lax
state of the tube which disappear when distended. Houston has described three

3T2

1012
THE ORGANS OF DIGESTION
oblique semilunar folds, which project into the lumen of the tube: one in front by
the prostate, and two others higher up; one from the left side, and one on the
right, the highest.
Structure of the large intestine. There are four coats: a serous, muscular,
submucous, and mucous.
The serous is derived from the peritoneum, and is more or less complete.
The appendices epiploicæ in connection with this layer have been mentioned
(fig. 576).
The muscular coat is divided into circular and longitudinal layers, the longi-
tudinal being external. The arrangement of the longitudinal fibres has been
described in as far as they make up the three longitudinal bands (fig. 576). Only
a small amount of longitudinal fibres are found between the bands, except on the
vermiform appendix and lower part of the sigmoid flexure, where they are arranged
all round.
The circular fibres form a thin layer, and are mostly collected in the interval
between the sacculi.
The mucous membrane, separated from the muscular layer by the submucous
layer, has no villi, and no valvulæ conniventes.
Blood-vessels. The large intestine is supplied with blood by the branches of the
superior mesenteric and inferior mesenteric arteries, while it also receives a blood-
supply from the internal iliac at the rectum. The vessels form a continuous series.
of arches from the cæcum, where the vasa intestini tenuis anastomose with the
ileo-colica, the first branch of the superior mesenteric given to the large intestine.
The blood-supply of the rectum is from the inferior mesenteric by the superior
hæmorrhoidal, from the internal iliac by the middle hæmorrhoidal, and from the
internal pudic by the inferior hæmorrhoidal. The vessels at the lower end of the
rectum assume a longitudinal direction, communicating freely near the anus, and
less freely above.
The blood of the large intestine is returned into the portal vein by means of the
superior mesenteric and inferior mesenteric veins. At the rectum a communication
is set up between the systemic and portal system of veins, since some of the blood
of that part of the intestine is returned into the internal iliac veins. In the lower
end of the rectum the veins, like the arteries, are arranged longitudinally. This
arrangement is called the hæmorrhoidal plexus.
The nerves and lymphatics of the large intestine differ in no important
particular from those of the small intestine.
THE LIVER
The liver-the largest gland in the body-is situated in the upper and right
part of the abdominal cavity (figs. 565, 578). It is of most irregular shape. It
weighs between fifty and sixty ounces. In females the liver is smaller than in
males. It bears a different relation to the body weight at different ages. It forms
one-fortieth part of the weight of the body in the adult male, and one-thirty-
sixth in the adult female. In the foetus, at the fourth month, it is one-tenth the
weight of the body, and in the infant at birth one twenty-fourth (fig. 578). It
measures from right to left ten to twelve inches, from before backwards six to
seven inches, and three and a half inches from above downwards in the thickest
part of the right lobe. It is of a chocolate or reddish-brown colour, is solid and
firm to the touch, but friable. Its bulk is equal to ninety-five cubic inches.

THE LIVER
1013
In the description which follows it will be noted that there are two borders-
anterior and posterior; two extremities-right and left; three surfaces-superior,
inferior, and posterior; five lobes-right, left, quadrate, caudate, and Spigelian;
five fissures-umbilical, fissure for the ductus venosus, transverse, fissure of the
vena cava, fissure for the gall bladder; five ligaments-coronary, suspensory or
falciform, round, right and left lateral.
The liver is seen to be divided by means of a fold of peritoneum-the suspen-
FIG. 578.-THE VISCERA OF THE FETUS. (Rüdinger.)

UD EU
THYROID
-TRACHEA
LUNG
LIVER
Suspensory ligament-
SMALL INTESTINE
BLADDER-
-THYMUS
LUNG
-RIGHT AURICLE
RIGHT VENTRICLE
STOMACH
PART OF TRANSVERSE
COLON
Hypogastric artery
sory ligament-into two very distinct parts, the right and left lobes (figs. 578, 579).
The anterior border of the liver is well defined, appearing as a sharp thin edge.
To the left of the middle point at the beginning of the longitudinal fissure is the
interlobar notch, marking the division between the right and left lobes. Further
to the right is a notch for the gall bladder.
The posterior border is thick, rounded, and fixed, is slightly marked by the
spinal column, and notched for the vena cava.
The right extremity is thick and rounded like the posterior border. The left
extremity is thin and flat like the anterior border.

1014
THE ORGANS OF DIGESTION
The surfaces are described as they are seen in a liver which has been hardened
in situ.
The superior surface of the liver is convex, and moulded to the surface of the
diaphragm. It is smooth, and is covered by peritoneum. It is divided by the sus-
pensory ligament, which runs from before backwards, into two parts: the right and
left lobes, the right division being much the larger (fig. 579). Upon this surface of
the left lobe is a shallow depression for the heart. The surface of the left lobe
is much less convex than that of the right.
The inferior surface consists of that part of the liver in front of and including
the transverse fissure. It is irregularly concave. It is covered by peritoneum,
except where the gall bladder comes in contact with its surface, and at the trans-
verse fissure where the lesser omentum leaves the liver. It consists of three parts
-viz. the quadrate lobe, nearly all the left lobe, and the under surface of the right
lobe (fig. 580). This inferior surface is divided into right and left sections by
the longitudinal fissure which forms the inferior separation between the right and
left lobes. The part of the longitudinal fissure seen on this surface is known as
FIG. 579.-SUPERIOR SURFACE OF THE LIVER.
RIGHT LOBE
Site of the Spigelian lobe
LEFT LOBE
GALL BLADDER
Falciform or suspensory ligament
the umbilical fissure from its containing during foetal life the umbilical vein, the
remains of which are now to be seen as the round ligament. It runs from before
backwards, meeting the transverse fissure behind. The portion of the left lobe
included on this surface is much smaller than the similar surface of the right lobe.
It lies over the cardiac part of the stomach and the anterior surface adjoining the
lesser curvature, and shows an impression (impressio gastrica) made by that organ.
Its anterior border is sharp and free; but behind, the separation from the posterior
surface is very ill defined.
The under surface of the right lobe is divided into two by the gall bladder, which
is contained in a fossa (the fossa of the gall bladder). The inner of these two
portions, which is bounded by the umbilical fissure to the left, the fossa of the gall
bladder to the right, and the transverse fissure behind, is called the quadrate lobe,
and is connected with the left lobe very often by a bridge of liver substance (pons
THE LIVER
1015
hepatis) across the umbilical fissure. The outer of the two portions is much the
larger, and presents three depressions upon its surface: an anterior one for the
hepatic flexure of the colon (impressio colica), a posterior one for the right
kidney (impressio renalis), and one situated on the inner side of the impressio
renalis for the descending part of the duodenum (impressio duodenalis). In a
hardened liver these impressions are well marked, and are separated by well-defined
ridges.
The posterior surface is directed backwards towards the vertebral column, at
which part it is concave. It includes that part of the liver behind the transverse
fissure, and consists of the following parts (fig. 581):-
(1) The posterior portion of the left lobe, not very well defined; it presents a
protuberance (the tuber omentale) in front, which projects against the lesser
omentum; behind, a concavity coming in contact with the cardia.
This portion is separated by means of the fissure of the ductus venosus from (2)
the Spigelian lobe, which lies between this fissure and that of the vena cava. This
FIG. 580.-THE INFERIOR SURFACE OF THE LIVER.

Vena cava
BILE DUCT
Portal vein
Hepatic artery
SPIGELIAN LOBE
IMPRESSIO
CASTRICA
TUBER!
COMENT
IMPRESSIO
RENALIS
CAUDATE
LOBE
IMF.
DUOD
QUADRATE CALL
LOBE
IMPRESSIO
COLICA
BLADDER
UMBILICAL FISSURE
lobe is directed backwards, is longer from above downwards than from side to side,
and is somewhat concave from side to side. It is opposite to the tenth and eleventh
thoracic vertebræ, and rests on the crura of the diaphragm. Behind its upper left-
hand corner the oesophagus passes to enter the stomach. Below, it projects and
forms part of the posterior boundary of the transverse fissure. It is connected
with that part of the right lobe which enters into the posterior surface by means
of (3) the caudate lobe, which is a small mass of liver substance running from left
to right behind the transverse fissure. It lies directly over the foramen of
Winslow. It varies a good deal in form; is sometimes well defined, at other times
hardly to be seen.
When well defined it is about two to three inches long; behind
is the termination of the fissure of the vena cava.
(4) The portion of the right lobe taking part in the posterior surface consists of a
strip two and a half to three inches broad (Quain). This is uncovered by peritoneum,
except at the extreme right. Lying between the two layers of the coronary ligament
close to the vena cava and near the caudate lobe is an impression for the right
suprarenal capsule (impressio suprarenalis).

1016
THE ORGANS OF DIGESTION
Fissures. The fissures on the inferior and posterior surfaces of the liver are
arranged very like a capital letter H. The left upright of the H is formed by the
longitudinal fissure; the anterior portion containing the umbilical vein is seen on
the inferior surface, and is known as the umbilical fissure; the posterior portion,
seen on the posterior surface, contains the ductus venosus, and is therefore called
the fissure of the ductus venosus. The transverse bar of the H is formed by the
transverse or portal fissure, which runs across at right angles to the longitudinal
fissure, and contains the vessels entering the liver, viz. the portal vein, hepatic
artery, and hepatic duct (fig. 580).
The right upright of the H is formed by the fossa of the gall bladder in front;
it is interrupted by the caudate lobe; and is continued behind as the fissure of
the vena cava, containing, as its name implies, the inferior vena cava.
General position. The liver is situated in the right hypochondriac and epigastric
regions, and usually extends into the left hypochondrium (fig. 582). It is opposite
the tenth and eleventh dorsal vertebræ behind (fig. 583), and on the right side extends
between the seventh and eleventh ribs; in front, it lies behind the sixth, seventh,
FIG. 581.-POSTERIOR SURFACE OF THE LIVER.
LEFT LOBE
SPIGELIAN LOBE
Vena cava
RIGHT LOBE
eighth, and ninth costal cartilages; and its anterior border corresponds on the right
to the line of the margin of the costal cartilages, and to the left it is in contact
with the anterior abdominal wall below the sternal notch (fig. 582).
The liver is very movable, and alters its position under various circumstances.
It is depressed at each inspiration, the anterior border being pushed below the
ribs with a deep breath. When lying down, the liver edge is an inch or an inch
and a half above the margin of the ribs. In children, the gland being larger
in proportion to the body than in the adult state, it extends below the ribs and
reaches the left hypochondrium.
The liver's extreme left point is about an inch and a half beyond the left margin
of the sternum; in front, in the middle line, it reaches to about half way between
the xiphoid cartilage and the navel. The lower edge as it crosses the subcostal
angle is represented by a line drawn from the ninth right to the eighth left costal
cartilage. (Quain.)
Its upper limit is indicated by a line crossing the meso-sternum close to its
lower end, and rising on the right side to the level of the fifth chondro-sternal

THE LIVER
1017
articulation, and on the left to that of the sixth. Behind, the liver is nearest the
surface at the tenth and eleventh thoracic vertebræ.
Its upper convex surface is in contact with the whole of the right arch of the
diaphragm and a part of the left, as well as with the ribs and the anterior wall of
the abdomen.
The under surface. The left lobe lies over the cardiac end and a portion of
the anterior wall of the stomach.
The right lobe lies over the hepatic flexure of the colon and right kidney, and
descending portion of the duodenum.
FIG. 582.-RELATION OF THE ABDOMINAL VISCERA TO THE PARIETES. (Treves.)

LIVER
4
5
STOMACH
KIDNEY TRANS.COLON
KIDNEY 9
10
The quadrate lobe lies over the pyloric end of the stomach and first part of
the duodenum.
The posterior surface. The Spigelian lobe lies against the tenth and eleventh
thoracic vertebræ, the right crus of the diaphragm, and the lower end of the
œsophagus. That portion of the right lobe which takes part in this surface lies
against the right suprarenal capsule and diaphragm.
The inferior vena cava lies in a groove in this lobe. The small portion of the
left lobe taking part in the posterior surface lies against the oesophagus.

1018
THE ORGANS OF DIGESTION
The fundus of the gall bladder is opposite to the ninth costal cartilage, close to
the outer margin of the right rectus muscle.
Relation to the peritoneum.-The liver is received between the layers of the
gastro-hepatic omentum. The anterior layer on leaving the transverse fissure passes
along to the anterior border of the liver, where it meets the round ligament, encloses
it, and is then continued on to the superior surface in two portions, owing to the
intervention of the round ligament, the two layers reflected on to this structure
being known as the suspensory ligament. At the posterior border of the superior
surface it leaves the liver and forms the upper layer of the coronary ligament.
FIG. 583.-RELATION OF THE ABDOMINAL VISCERA TO THE PARIETES. (Treves.)
SPLEEN
STOMACH
LIVER
KIDNEY
KIDNEY
RECTUM
The posterior layer of the gastro-hepatic omentum passes backwards, covers a
portion of the posterior surface of the liver, and leaves uncovered that part of the
right lobe (except the extreme right) which takes part in this surface. It is finally
reflected to form the inferior layer of the coronary ligament.
The parts of the liver uncovered by peritoneum are: the transverse fissure, the
fossa of the gall bladder, and that portion of the posterior surface made up by the
right lobe, and to which allusion has already been made.
Underneath the peritoneal investment of the liver is a thin fibro-elastic membrane
THE LIVER
1019
which is intimately adherent to the peritoneum, and is continuous over the liver
where the peritoneum is deficient. At the transverse fissure this fibrous layer
invests the hepatic vessels, forming a special sheath which follows the vessels as
they enter the liver: this structure receives the name of Glisson's capsule.
ABOVE.
Diaphragm and anterior wall of abdomen.

BEHIND.
Tenth and eleventh thoracic verte-
bræ; crura of diaphragm; lower
end of oesophagus; right supra-
renal capsule; great vessels.
GENERAL
RELATIONS
OF THE LIVER
BELOW.
Cardiac end of stomach; hepatic flexure of colon; right kidney; first and second portions
of duodenum.
Ligaments of the liver.-With the exception of the round ligament, the liga-
ments are formed by the peritoneum, and (with the same exception) are all attached
to the diaphragm. The reflexion of the two layers of peritoneum from the posterior
surface of the liver to the diaphragm, as just described, forms the coronary ligaments,
the extremities, or lateral continuations, being called the right and left lateral
ligaments. The left lateral ligament is the longer, and is attached to the diaphragm
in front of the œsophagus. The right is attached to the back part of the
diaphragm.
The broad ligament (falciform or suspensory ligament) is also continuous
behind with the coronary ligament; it is formed by the adjacent surfaces of the
two portions of peritoneum covering the superior surface; it extends from the
umbilicus where is the apex of the falx. The upper rounded border is connected
with the anterior abdominal wall and diaphragm. The free or anterior border
contains the round ligament; the lower or attached border extends from before
backwards on the upper surface of the liver.
The round ligament is a fibrous cord (the remains of the umbilical vein), extending
on the free border of the broad ligament from the longitudinal fissure to the
umbilicus.
Blood-vessels. The liver receives its arterial supply of blood from the hepatic
artery, a branch of the coeliac axis, which passes up between the two layers of the
lesser omentum, and, dividing into two branches, one for each lobe, enters the liver
at the transverse fissure. The right branch gives off a branch to the gall bladder.
The liver receives a much larger supply of blood from the portal vein, which
conveys to the liver blood from the stomach, intestines, pancreas, and spleen. It
enters the transverse fissure, and there divides into two branches. Below this
fissure the hepatic artery lies to the left, the bile duct to the right, and the portal
vein behind and between the two (fig. 584). These three structures ascend to the
liver between the layers of the gastro-hepatic omentum in front of the foramen
of Winslow. At the actual fissure the order of the three structures from before
backwards is duct, artery, vein.
The hepatic veins, by which the blood of the liver passes into the inferior vena
cava, open by several large and small openings into that vessel at the posterior
surface of the gland at the bottom of the fossa of the vena cava.
Lymphatics. The lymphatics are divided into a deep and a superficial set. The
deep set run with the branches of the portal vein, artery, and duct through the liver,
leaving at the transverse fissure, where they join the vessels of the superficial set.
The superficial set begin in the subperitoneal tissue. Those of the upper
surface consist :-(1) Of vessels which pass up, principally, in the broad ligament



1020
THE ORGANS OF DIGESTION
and right and left lateral ligaments, through the diaphragm, and so into the anterior
mediastinal glands; occasionally lymphatics of the right ligament pass straight
into the thoracic duct. (2) Of a set passing over the anterior border of the liver
to the glands in the small omentum about the transverse fissure.
On the under surface, the lymphatics to the right of the gall bladder enter the
lumbar glands.
Those round the gall bladder enter the glands of the lesser omentum.
Those to the left of the gall bladder enter the glands of the oesophagus and
lesser curvature of the stomach.
Structure of the liver.-If a section be made of the liver, the following features
in its general structure may be noted:-
Outside of all will be seen the investment of peritoneum, which is incomplete
in parts, and which has been already described.
Within this a thin fibrous coat will be observed to invest the entire gland. At
the transverse fissure this coat turns into the substance of the liver with the
branches of the portal vein.
Glisson's capsule. The capsule is in all parts closely adherent to the gland-
substance, and is thickest where the peritoneum is absent.
The liver on section is seen to be mottled, and when a portion is torn the
FIG. 584.-RELATION OF STRUCTURES AT AND BELOW THE TRANSVERSE FISSURE. (Thane.)
GALL BLADDER
BILE DUCT-
Portal vein
Hepatic artery
surface presents a granular appearance. This is produced by the minute lobules
(one twenty-fourth to one-twelfth of an inch in diameter) of which the liver tissue
is composed.
The cut surface will also exhibit the openings of a number of canals. A slight
examination will show that these are of two kinds-viz. the canals for the branches
of the portal vein and the canals for the hepatic veins.
In the portal canals the vein is accompanied by a branch of the duct and a
branch of the hepatic artery. The vein has thick walls which will be seen to be
more or less collapsed on section. The vessels in the canal are separated from
the liver substance by much connective tissue (Glisson's capsule, fig. 585).
In the hepatic canals the veins are solitary, their walls are exceedingly thin,
and their mouths open and gaping. The wall of the vein is directly adherent to
the liver substance, no connective tissue capsule intervening.
The gall bladder, which retains the bile, is situated between the right and
quadrate lobes on the under surface of the liver. It is of pyriform outline, and
when full is seen projecting beyond the anterior border of the liver, coming in
contact with the abdominal wall at the cartilage of the ninth or tenth rib. It
extends back as far as the transverse fissure.
It measures in length, from before backwards, from two and a half to four inches,
and an inch and a half across at the widest part, and will hold about one ounce.

THE GALL BLADDER
1021
The broad end of the sac is directed forwards, downwards, and to the right, and is
called the fundus. The narrow end, or neck, which is curved first to the right,
then to the left, is at the transverse fissure. The intervening part is called the
body.
Its upper surface is in contact with the liver, lying in the fossa of the gall
bladder. It is attached to the liver by connective tissue. The lower surface is
covered by peritoneum, which passes over its sides and inferior surface, though
occasionally it entirely surrounds the gall bladder, forming a sort of mesentery to
attach it to the liver. The lower surface comes into contact with the first part of
the duodenum and hepatic flexure of the colon, and occasionally with the pyloric
ends of stomach or small intestine, which are often post mortem found stained
with bile.
The neck of the gall bladder opens into the cystic duct. This is a tube an
inch to an inch and a half long, which unites with the hepatic duct to form the
common duct; it is directed backwards and to the left as it runs in the lesser
omentum, the hepatic artery being to the left, and the portal vein behind. It joins
the hepatic duct at an acute angle.
The hepatic duct begins with a branch from each lobe right and left in the
FIG. 585.-SECTION OF A PORTAL CANAL. (Quain.)

BILE DUCT
LYMPHATICS IN GLISSON'S CAPSULE
Portal vein
LYMPHATICS IN GLISSON'S CAPSULE
Artery
transverse fissure, and is directed downwards and to the right in the folds of the
lesser omentum, the hepatic artery being to the left. It is not quite two inches
long. Uniting with the cystic duct, it forms the common bile duct (ductus com-
munis choledochus).
The common bile duct is about three inches in length. It passes down between
the layers of the lesser omentum, in front of the portal vein, and to the right of the
hepatic artery (fig. 584); it then passes behind the first part of the duodenum, then
between the second part and the head of the pancreas, and ends at the lower part
of the second segment of the duodenum by opening into that part of the intestine
on its left side and somewhat behind (figs. 571, 586, and 587). It pierces the intes-
tinal wall very obliquely, running between the muscular layer for about three-
quarters of an inch; there is a slight constriction at its termination. The
pancreatic duct is united with the common bile duct just before its termination.
There is a slight papilla at their place of opening on the mucous surface of
the duodenum. This papilla is about four inches from the pylorus. After the
pancreatic duct has entered the bile duct there is a dilatation of the common
tube called the ampulla of Vater.
The common duct has a diameter of about two lines. Its width at the


1022
THE ORGANS OF DIGESTION
ampulla is three lines. It is narrowest at its outlet into the duodenum. The cystic
and hepatic ducts are a little narrower than the common duct.
Structure of the gall bladder.-The wall of the gall bladder is made up of
three coats-serous, muscular or fibrous, and mucous.
FIG. 586.-ABDOMINAL VISCERA, FROM BEHIND. (Rüdinger.)
LARYNX
Aorta
GULLET
BRONCHUS
LUNG
LUNG
DIAPHRAGM
PANCREAS
SPLEEN
STOMACH
Vena cava
-LIVER
DUODENUM
DESCENDING COLON
Inferior mesenteric
vein
Superior mesenteric
vein
ASCENDING COLON
1. The serous coat being formed by the peritoneum, is only found on the lower
surface and part of the sides. Beneath this coat is a nerve plexus.
2. The fibrous coat consists of plain muscular fibres and fibrous tissue. The
muscular fibres run mostly longitudinally, some transversely. The fibrous tissue
consists of white fibres running in every way. This layer contains the principal
blood-vessels and lymphatics, and also contains a nerve plexus.
THE GALL BLADDER
1023
3. The mucous coat is raised into rugæ bounding polygonal spaces, which are
largest about the body. It is lined with columnar epithelium, and contains many
mucous glands. At the neck the mucous membrane forms folds which project
into the interior, acting as valves. This layer contains an anastomosis of blood-
vessels, and a fine plexus of lymphatics.
The ducts consist of a fibrous and a mucous layer. In the fibrous layer
are muscular fibres which are chiefly circular, together with many strong white
connective tissue and elastic fibres. The mucous layer is lined with columnar
epithelium, and has many mucous glands. In the cystic duct the mucous membrane
is raised into folds, which are crescentic in form, and so directed obliquely as to
seem to surround the lumen of the tube in a spiral manner.
VARIETIES OF THE LIVER
Varieties are more rare in the liver than in almost any other organ of the
body.
The left lobe may be very small; on the other hand, it may be much larger,
occasionally extending in an attenuated form much more towards the left. The
left lobe, or a portion of it, may be attached only by a pedicle of peritoneum and
vessels to the main organ. The gall bladder has been seen through an opening
in the upper surface, owing to the depth of the fossa of the gall bladder.
The liver may be subdivided into many lobes, or may show no division at all.
It may retain the thick rounded form of the foetus. The gall badder may be
absent, in which case the hepatic duct usually becomes much dilated before it
reaches the duodenum.
The gall bladder may be partially divided either transversely or longitudinally.
The common duct may enter the bowel independently of the pancreatic duct.
THE PANCREAS

The pancreas is situated in the epigastric and left hypochondriac regions. It
is a compound racemose gland. It lies transversely across the body, on a level with
the first lumbar vertebra, and is deeply placed (fig. 577). It differs in shape as it is
examined in situ, or removed from the body. When examined in situ it shows
various impressions for the different organs with which it is in contact (figs. 570,
571); when removed from the body it appears to be longer, and runs to a point at
the left extremity (fig. 587). It is of a pinkish-cream colour and soft in texture.
It shows upon its surface the markings between the lobules of which it is made up.
It may be divided into three portions: a head, a body, and a tail. The head of
pancreas is situated at the right extremity of the gland, and is contained in
the loop of the duodenum. The head is bent downwards, so that it extends lower
than the lower border of the body. Behind it are found the common bile duct,
which runs, as a rule, in a canal in its substance, and the vena cava (fig. 571). A
portion of the head, to which, the name lesser pancreas has been given, situated
at the lower part, hooks round the superior mesenteric vessels, making a groove,
or even a canal, for them. In front of the head is the attachment of the transverse
meso-colon and the stomach.
the
According to Professor His, there are three surfaces on the body of the pancreas:
anterior, inferior, and posterior. The body extends from the head of the gland

1024
THE ORGANS OF DIGESTION
to the spleen; it is situated transversely across the vertebral column with the large
vessels intervening.
The anterior surface is in contact with the stomach, which organ gives a
concavity to the surface (fig. 590). This surface is covered by peritoneum derived
from the ascending layer of the transverse meso-colon.
The posterior surface is in contact with the crura of the diaphragm, the aorta,
vena cava, and superior mesenteric vessels, which structures are interposed between
it and the spine (figs. 571, 586). The splenic artery and vein run lengthways above
the back of the upper border of the posterior surface. To the left, the posterior
surface is in contact with the left kidney and suprarenal capsule. The upper
border in the middle line abuts against the cœliac axis.
The inferior surface is narrow, and lies over the third part of the duodenum and
beginning of the jejunum. The transverse meso-colon is continued from the front
of the head along the border separating this surface from the anterior surface.
The splenic end of the transverse colon lies under the left extremity of this surface.
From the under surface of the transverse meso-colon a layer of peritoneum passes
to the central part of the inferior surface.
FIG. 587.-THE PANCREAS AND ITS DUCT.
DUCT OF PANCREAS
DUCT OF PANCREAS
COMMON BILE DUCT
The tail of the pancreas is the name given to the left extremity of the organ;
it touches the anterior surface of the spleen.
The duct of the pancreas, or the canal of Wirsung, white in appearance, runs
from nearly the extreme left of the gland, concealed by the proper substance of the
pancreas, nearer its posterior surface than the anterior, between the upper and lower
borders, to empty into the lower and inner part of the second portion of the duodenum
with the common bile duct. It runs sinuously, receiving its branches as it goes,
which enter nearly at right angles. These branches are straight. Its diameter near
its termination is one-eighth of an inch. Near its termination it is generally joined
by another duct, that of the lesser pancreas, though this may open into the duo-
denum separately (fig. 587). The pancreatic duct often does not join the common
bile duct until its termination, running side by side with it through the walls of the
intestine. Occasionally the pancreatic duct opens by itself into the duodenum.
Blood-supply. The pancreas receives blood from the splenic artery through
its pancreatic branches, and from the superior mesenteric and hepatic by the
inferior and superior pancreatico-duodenal arteries, which form a loop running
round, below, and to the right of its head.
The blood is returned into the portal vein by means of the splenic and superior
mesenteric veins.
THE SPLEEN
1025
Lymphatics. The lymphatics terminate in two glands which lie on the
superior mesenteric artery.
Nerves. These are branches of the solar plexus which accompany the arteries
entering the gland.
THE SPLEEN
Position. The spleen-one of the ductless glands-is situated for the most
part in the left hypochondriac region (figs. 577, 591). It is deeply placed between
the fundus of the stomach and the diaphragm, and in the line of the axilla it
extends between the eighth and eleventh ribs. It is covered by the ninth, tenth,
and eleventh ribs (fig. 583), and is separated from them by the diaphragm and to a
smaller extent by the lung. Its upper end reaches to the level of the ninth thoracic
spine, and its lower end to the level of the first lumbar spine. Its inner extremity
is within two inches of the median plane of the body, and its outer boundary is
posterior to the mid-axillary line. A line drawn from the left sterno-clavicular
joint to the tip of the eleventh left rib bounds the anterior margin of the spleen.
It is bluish-red in colour, is soft, and easily lacerated.
FIG. 588.-OUTER ASPECT OF THE SPLEEN.

ANTERIOR BORDER-
EXTERNAL
SURFACE
LOWER END
Its shape varies, and depends much upon the condition in which it is examined.
If soft, and as usually found after removal from the body, it can only be said to
have two surfaces, an outer convex and an inner concave; but if examined after
it has been hardened in situ, after the manner of Professor His, it is seen to be of
a much more precise shape, and to present three surfaces (fig. 590).
Viewed from the outside, it presents a form which is irregularly oval, wider
above than below, with a bulging of the anterior border (fig. 588). The three
surfaces are the external, anterior, and inner. The external or posterior surface is
the largest. It is regularly convex, and is directed outwards and backwards and
somewhat upwards (figs. 588, 590). It lies against the commencement of the
arch of the diaphragm. It is covered by peritoneum. Viewed from the inside, the
two other surfaces are seen to be divided by a distinct vertically directed ridge (fig.
590). The anterior of the two looks forwards, inwards, and a little downwards.
It is concave from above downwards, and from side to side. It is a good deal the
3 U

1026
THE ORGANS OF DIGESTION
larger of the two, and is semilunar in shape (fig. 589). It is in contact with the
great cul-de-sac of the stomach, with the tip of the pancreas, and the extreme
point of the splenic flexure of the colon (fig. 586). Near the posterior border of this
FIG. 589.-INNER ASPECT OF THE SPLEEN.
INNER SURFACE
ANTERIOR SURFACE
TIP OR LOWER END
EDGE OF GASTRO-SPLENIC
OMENTUM
surface and bounded by the ridge is seen the hilum of the spleen, a depression
running vertically from above downwards. It is here that the splenic artery and
vein enter the gland, the vein being behind. In front of and behind the hilum
FIG. 590.-TRANSVERSE SECTION OF THE BODY AT THE LOWER PART OF THE
EPIGASTRIC REGION. (Rüdinger.)
TRANSVERSE COLON Aorta
PANCREAS
SUPRA-RENAL
CAPSULE
SPLEEN
STOMACH
KIDNEY
Vena cava
KIDNEY
00
LIVER
LOBUS
00
SPIGELII
IMPRESSIO
RENALIS
is seen the attachment of the gastro-splenic omentum. The ridge separating this
surface from the inner surface is well defined, and runs
to the lower part of the posterior border.
from the top of the spleen
The inner or renal surface is much narrower and shorter than the anterior.

THE SPLEEN
1027
It is only slightly concave in both directions. It is directed inwards, and is in
relation with the outer border of the left kidney.
The anterior border of the spleen is more defined than the posterior, is sharper,
and is marked by several notches, one of which is occasionally larger than the
others. This border is convex. The posterior border is shorter and straighter.
The lower end or apex of the spleen rests on the costo-colic ligament.
The spleen is set obliquely in the body. Its long axis about corresponds to
the line of the tenth rib.
FIG. 591.-VIEW OF THE SPLEEN, ETC. FROM BEHIND. (Rüdinger.)
LUNG
Diaphragm
STOMACH
SPLEEN
KIDNEY
e-boold
DESCENDING
COLON
Psoas
O ZON
In size it varies, owing to the fact that it increases in dimensions after food and
under other circumstances. In the adult it measures generally about five to six
inches in length, three or four inches in breadth, and one to one and a half inch
in thickness; its usual volume, according to Krause, is from nine and three-quarters
to fifteen cubic inches.
It is entirely surrounded by peritoneum except at the hilum. On either side of
the hilum the gastro-splenic ligament is attached. This reflexion of peritoneum,
sometimes called the gastro-splenic omentum, passes inwards to the left extremity
of the stomach and the left margin of the great omentum. A fold of peritoneum,
the phreno-splenic ligament, connects the upper end of the spleen to the diaphragm.
Varieties. The principal peculiarity is due to the presence of supplementary
3U2
1028
THE ORGANS OF DIGESTION
spleens (lienculi), found in the gastro-splenic omentum, or less often in the great
omentum. From one to twenty of these small bodies may be met with. They are
red and round, of the same structure as the spleen, and vary in size from a pea to
a walnut.
Structure. Beneath the covering of peritoneum is a thin but tough capsule of
areolar tissue, which is very adherent to the serous membrane. It is remarkably
elastic. It sends a prolongation in at the hilum, which follows and supports the
vessels to their termination. Within the capsule is the pulp. This is a very
friable soft tissue of a dark reddish-brown colour, not unlike grumous blood in
colour and consistence. It can be squeezed out from the cut spleen, and then it
will be seen that the whole organ is pervaded by a network of fine fibres which
support the pulp. The larger of these come off directly from the fibrous capsule,
and are called the trabecula.
IN FRONT.
Stomach; splenic flexure of colon.

OUTER SIDE.
GENERAL RELATIONS
Diaphragm; ninth to eleventh
ribs between axillary line.
OF
THE SPLEEN
INNER SIDE.
Stomach; pancreas; left kidney
and capsule.
BEHIND.
Diaphragm.
Blood-supply. The spleen receives its blood from the
very large in proportion to the body it is going to supply.
into about six branches. The artery is very tortuous.
hand, is straight, and lies below the artery.
splenic artery, which is
It divides before entering
The vein, on the other
The lymphatics are divided into a superficial and a deep set. The former forms
a plexus beneath the peritoneum. The latter are derived from fine perivascular
spaces in the adenoid tissue around the vessels. They join at the hilum, and
pass between the layers of the gastro-hepatic omentum to the glands in that
neighbourhood.
The nerves are from the solar plexus. They pass in along the splenic artery.
THE EVOLUTION OF THE PERITONEUM AND AN EXPLANATION
OF ITS ARRANGEMENT IN THE HUMAN BODY
The peritoneum is a serous membrane and is identical with other like-named
membranes which are less complicated in their disposition. It differs in no
essential particular from the pleura, from the pericardium, from the tunica vaginalis,
from the synovial membrane of a joint, or from the simple vaginal sheath of a
tendon. In all there is practically a closed sac of thin membrane, which is so
disposed as to both line a cavity and to invest the structures which encroach upon
that cavity.
Imagine a pleural cavity from which the lung had vanished without disturb-
ance of parts. The membrane lining it would appear as a simple serous bag.
Next conceive the lung gradually budding towards this sac. It would push the
membrane before it, and as it did so it would both encroach upon the cavity lined
by the membrane, and be itself covered or invested by it.
When the lung had attained nearly to the dimensions of the rigid cavity it was

THE PERITONEUM
1029
occupying, the serous lining would be found to invest the whole of it excepting
only its pedicle the stalk of the original bud-the root of the lung.
Although the thoracic space might be almost obliterated, the lung would still
remain entirely outside the cavity of the serous sac. It would be convenient then
to speak of the undisturbed layer which still lined the thoracic space as the parietal
layer, and the layer which had come in a passive way to invest the lung as the
visceral layer.
In the abdomen a similar condition exists. Imagine all the viscera to have
vanished from the abdominal cavity. A great space would exist, bounded above by
the diaphragm, below by the pelvic floor, and in front and behind by the abdominal
parietes. This space would be evenly lined by the peritoneum in the form of a
simple closed sac. As the viscera reappeared they would emerge, as it were, from the
posterior wall of the belly, and would project into the cavity of the abdomen.
In so doing they would push before them the peritoneum lining the posterior wall
of the cavity, and would each in turn become invested by the displaced membrane.
All the abdominal viscera are outside the peritoneal cavity, although they are
obviously within the abdominal space. The peritoneal sac remains entirely empty,
and its wall, with the exception of the Fallopian orifices, is unbroken.
That part of the simple sac which lines the anterior abdominal parietes is
practically the only part which retains its original connections undisturbed.
One main function of a serous membrane is to minimise the effects of friction.
Those viscera which are exposed to most movement, such as the small intestines,
are the most completely invested by the smooth membrane; those which remain
fixed, such as the kidney, are only casually invested. The movements of the
viscera in respiration, the alteration in shape and position which will occur in such
organs as the stomach and bladder, are provided for by the peritoneum in such a
manner that these movements are practically without friction. todi to otie ada
The viscera contained in the abdomen are not only numerous, but they are of
very complex outline for the most part, and they are disposed in a manner which
tends to greatly confuse their relations with one another.
A bare description of the peritoneum, as it is met with in the human subject,
must needs be intricate and complicated, and if considered without reference to
more primitive and simpler conditions is almost inexplicable. The description
may be followed, but it needs interpretation, and no account of this membrane can
be considered to be satisfactory unless it be rendered evident how the complex
arrangement has come about, and unless the student base his conceptions upon the
simple and rudimentary disposition which an elaborate development of parts and
a remarkable specialisation of structure have rendered intricate and confusing.
The readiest idea of the disposition of the peritoneum is to be derived from a
study of the development and most rudimentary forms of that membrane. Such
a study is founded upon an examination of the human embryo at various periods,
and of the peritoneum in the mammalia and lower animals.
The simple alimentary tube.-The alimentary canal first appears as a simple
tube lying about the median line in front of the posterior abdominal parietes, and
placed vertically. This tube is connected with the posterior parietes by a simple
fold of peritoneum-a species of general mesentery (fig. 592).
The fact that the abdominal cavity is at an early period open in front, and that
the rudimentary intestine protrudes beyond the limits of the future cavity, may be
disregarded. The cavity, such as it is, is lined by a membrane which is later
recognisable as the peritoneum, and the general mesentery is produced by the
growth and protrusion forwards of the elementary bowel from the tissues behind,
i.e. outside the peritoneum.
The simple straight tube, suspended on the posterior mesial line by its fold of
peritoneum, becomes in due course differentiated (fig. 592).



1030
THE ORGANS OF DIGESTION
The upper part becomes the stomach; the bowel immediately beyond forms the
duodenum; then follow the small intestine; and lastly the colon and rectum.
The point of separation of the small bowel from the colon is indicated by the
appearance of the cæcum.
FIG. 592.-DIAGRAM OF THE PRIMITIVE ALIMENTARY CANAL.
(A: a indicates the vitello-intestinal duct; b points to the future position of the cæcum.)
fgood
a
B
A
(A)
It will be understood also that the upper part of the mesial peritoneal fold is called
the meso-gaster (M-G, fig. 593); the next part the meso-duodenum (M-D); and the
succeeding portions, in order, the mesentery, the meso-colon, and the meso-rectum
(fig. 593, MES, M-C, M-R). The stomach becomes more distinctly marked; the tube
below lengthens and forms an intestinal loop, which in the embryo projects beyond
the site of the future umbilicus, taking the mesentery with it.
FIG. 593.-DIAGRAM OF THE PRIMITIVE ALIMENTARY CANAL.
LIVER
fale. lig.
gast.hepat.oment.
M:G
DUOD.
M-D
MES.
V.D.
CAC.
3M-C
M-R
This elementary condition of the intestinal canal persists in certain fully developed
animals. As an example may be taken the alimentary canal of the salamander, as
depicted in fig. 594. In this figure the viscera are shown undisturbed. In fig. 595,
the peritoneum has been drawn forwards so as to show the parts in one median
plane, and well represents the simple arrangement. In many mammals among the
THE ALIMENTARY CANAL
1031
Edentates the simple vertical median fold of peritoneum is retained. This is shown
in the great anteater and in Hoffmann's sloth (fig. 596), where the intestinal canal,
from the pylorus to the rectum, is still quite simple, although it is of considerable
length, and is, as a consequence, thrown into numerous coils. The whole of this
long tube is supported by a single median fold of peritoneum attached to the
middle line behind, and serving the purpose of meso-duodenum, mesentery, meso-
colon, and meso-rectum in one.
Where this fold is attached behind runs the aorta, and between the layers of
the fold vessels pass forwards to supply the viscera. (Fig. 592, B, A, represents the
intestinal tube to which an artery is passing.) There will be an artery to the
stomach (1, fig. 593) and the great mesenteric artery. The latter vessel will supply
the rudimentary duodenum, the small intestines, the cæcum, and such part of the
colon as is later on known as the ascending and transverse segments. The
arrangement of the vessel is shown in figs. 593, 2, and 596.
The descending colon and rectum are supplied by a separate vessel, the inferior
mesenteric, direct from the aorta (3, figs. 593 and 596).
At the summit of the primitive loop which forms the principal part of the intes-
FIG. 594.-ALIMENTARY CANAL OF SALAMANDRA MACULOSA.

GASTRO-HEPATIC
OMENTUM
CCELAC AXIS
COLON
LIVER
STOMACH
SPLEEN
tine will be the vitello-intestinal duct or vitelline stalk (v. D, fig. 593; a, fig. 592, A).
It is to this point that the great or superior mesenteric artery is directed. The
morphological ending of the superior mesenteric artery is at this spot, while
branches pass off from either side of it. The student may be reminded that a trace
of the vitelline duct may persist in the form of a process known as Meckel's
diverticulum, and that this process, when existing, is situated in the lower part of
the ileum not far from the cæcum (page 1003). In the adult the trunk of the artery
may be represented by a line drawn from its place of origin to a point on the ileum
from one to three feet from the cæcum.
The primitive intestinal loop increases in length, and forms longer and more
complex coils. A large part of these coils will lie without the abdomen, the
anterior abdominal wall being still incomplete.
The
As the loop lengthens, a species of neck forms which tends to become narrower.
upper part of this neck or strait is bounded or formed by the duodenum; the
lower part by that portion of the large bowel which is at a later period known as
the transverse colon (fig. 593).
The transverse colon and the duodenum are thus brought near together, and it
is noteworthy that, no matter how complex the relations of the bowel become, these
segments of the intestinal tube are never separated. In the narrow neck formed

1032
THE ORGANS OF DIGESTION
between them runs the trunk of the superior mesenteric artery. The great loop
beyond this neck will form the small intestine, the cæcum, and the ascending colon.
The descending colon retains its simple connections with the median line (fig. 593).
The mesentery does not increase in the same proportion as the intestines grow,
and hence the bowel is thrown into innumerable convolutions. In the human
subject the increase in the breadth of the mesentery is somewhat more noteworthy
than its increase in length.
There is a time, then, when the great mass of the intestine is supported by a
simple but extensive mesentery, which is entirely free, and which is attached behind
by means of a narrow neck bounded by the duodenum and the right end of the
transverse colon, and through which the superior mesenteric artery runs.
The great intestinal loop projects at first anteriorly and mesially. The small
intestine is above, the large intestine below (figs. 593, 595).
As the coils of bowel become more fully developed, it will be seen that all the
small intestines lie to the right hand side, and the cæcum and the commencement
of the colon to the left. The vasa intestini tenuis of the superior mesenteric
artery consequently arise from the right side of the vessel, while the ileo-colic, right
colic, and middle colic all arise from the left (fig. 593).
ANDRA
FIG. 595.-ALIMENTARY CANAL OF SALAMANDRA MACULOSA.
LIVER
ANT. PARIETES
MEDIAN FOLD
GASTRO
HEPATIC
OMENTUM
COLON
STOMACH
SPLEEN
Further development in this direction may not proceed, and the condition above
described is met with in some of the lower mammals as a permanent arrangement
(fig. 596).
The rotation of the intestinal canal.- As development proceeds, the plates which
are forming the anterior abdominal parietes approach one another, and the closure
of the cavity of the abdomen is imminent. The loops which have up to this time
projected beyond the site of the future umbilicus are now withdrawn into the
abdomen.
About this time a remarkable and quite characteristic rotation of the general
mesenteric fold takes place. The rotation is from left to right, and is around an
axis which may be represented by a line drawn from the neck or pedicle of the
common mesentery to the site of the vitelline duct. This is in fact the line of the
superior mesenteric artery (fig. 93). The rotation is therefore at the neck of
the great and complex loop of intestine, which neck, as has been already said, is
bounded by the duodenum and the right end of the transverse colon.
As a result of this rotation, the cæcum and the ascending colon turn over to
the right, while the great mass of the small intestines is brought to the left (fig. 597).
The lower end of the duodenum will be consequently carried to the left; the
transverse colon will lie in front of it instead of below it; and the superior mesen-

THE INTESTINAL CANAL
1033
teric artery (2, fig. 597), which must still run between these two segments of the
bowel, will now be described as passing over the duodenum, or as crossing its
anterior surface. It is needless to say that in the fully-developed body this artery
crosses the left end of the third part of the duodenum, and is behind the right end
of the transverse colon. It will be seen that, in spite of this revolution, the
duodenum and the transverse colon still retain their relations to one another, and
still mark the neck or pedicle of attachment of the common mesenteric fold. non
The effect of this rotation of the intestinal tube is shown in the diagram on the
next page (fig. 597).
The cæcum and ascending colon are now moved to the right; the transverse
colon is more distinctly transverse; the small intestine has passed over to the left
side. The right side of the mesentery has become the left side, and vice versa; and
the vasa intestini tenuis now appear to arise from the left border of the superior
FIG. 596.-ALIMENTARY CANAL OF CHOLEPUS HOFFMANNI.

COLON
SMALL
INTESTINE
SUP MESART
INF MES
ART
PYLORUS
MEDIAN LINE.
RECTUM
mesenteric artery instead of from the right (fig. 597). The duodenum is almost
hidden from view, and has been brought into close contact with the vertebral
column. The descending colon remains unchanged, and is supported by the
still undisturbed median fold of peritoneum.
The duodenum still has a meso-duodenum, and is still entirely invested by
peritoneum.
In man further changes take place, but in mammals below man the condition
just described is that which represents the normal arrangement. Fig. 597 may be
considered to represent in diagrammatic fashion the simple intestine of a carnivorous
animal.
In the human subject even development may not proceed beyond this point, and
the condition detailed may be met with in the adult as a permanent arrangement. I
have described some examples of this (The Anatomy of the Intestinal Canal and
Peritoneum in Man,' London, 1885; and 'Lancet,' Oct. 13, 1888). In these instances


1034
THE ORGANS OF DIGESTION

the whole of the small intestine, together with the cæcum and the ascending colon,
were slung from a common mesentery, the attachment of which to the posterior
parietes was by a narrow neck giving passage to the superior mesenteric artery,
and bounded by the duodenum and the transverse colon. In these subjects there
was no trace of the mesentery proper as it is found in the normal human body.
The duodenum had been deprived of its meso-duodenum, and the descending meso-
colon was comparatively scanty; but, with these and some minor exceptions, the
resemblance of the arrangement of the bowels to that met with in the lower animals
was very exact. It is the existence of this immature condition that predisposes to
certain forms of twist or volvulus of the bowel.
The progress of this rudimentary revolution of the intestinal tube may be noted
by observing the progress of the cæcum.
That prominent diverticulum lies at first below the loop forming the lesser bowel,
and then to its left side. It is at first without the abdomen, and is gradually with-
drawn in the progress of development through the rapidly closing umbilical opening.
It then lies about the middle of the belly and just below the liver. Later, it
passes to the right side, and then descends into the right iliac fossa.
FIG. 597.-DIAGRAM TO SHOW THE ROTATION OF THE INTESTINAL CANAL.

V.D.
CAC.
STOM.
It may be permanently arrested at any point of its course. In the condition
known as the congenital umbilical hernia, the gap in the anterior abdominal parietes
has never closed, and the protruding loop of bowel has never been quite withdrawn
into the abdomen. The sac of such a hernia is made out of the tissues of the
umbilical cord, and the contents are usually the cæcum and lower part of the
ileum, and not infrequently a Meckel's diverticulum. As has been mentioned
already, the cæcum may be found near the middle line or in the right hypochondriac
region (page 1007). It is then spoken of as undescended.
Final changes in the peritoneum.-Further changes in the position of the
intestine and in the arrangement of the peritoneum are finally brought about, and
these changes are almost entirely limited to the human subject. The intestine
grows, and other abdominal viscera are encroaching upon the peritoneum. This
membrane is mobile, is easily drawn from one point to another, and is capable
of considerable adjustment. It does not, however, continue to grow at the same
rate as the viscera which it serves to cover. The peritoneum is relatively more
extensive in the foetus than in the adult, and in the lower mammals than in man.
If the viscera grow out of proportion to the peritoneum, it is evident that the
reflexions of that membrane must here and there be shortened; and it is possible


THE PERITONEUM
1035
that a viscus which was at one time entirely covered by peritoneum may in due
course become almost bared of it. This is so. In the diagram (fig. 598) a transverse
section of the body is imagined, the section traversing the spot where the duodenum
and transverse colon are in relation at the neck of the great common mesentery.
Here, by reason of the rotation of the intestine from left to right, the mesenteric
lamina has become folded upon itself (A, fig. 598). The fold would be V-shaped,
open above, but coming to a point below. On transverse section the meso-
duodenum (M-D) and transverse meso-colon (M-c) can be seen side by side. Now a
constantly increasing demand upon the peritoneum is made by the rapidly growing
viscera. The membrane is drawn in this direction and in that. There is some
symmetry, however, within the abdomen, and the membrane may be conceived to
be drawn equally upon in the direction of the arrows R and L.
FIG. 598.-DIAGRAM TO SHOW THE RELATION OF THE PERITONEUM TO THE DUODENUM.
A.
T.C
M.C
C.
B.
T.C
D
M.D.
The result of such traction upon the peritoneum in this particular instance will
be to lessen the length of the transverse meso-colon, and to use up the meso-
duodenum altogether (fig. 598, B). That piece of bowel is indeed at last left uncovered
by peritoneum behind, and is brought into contact with the posterior parietes. The
serous membrane which formed the meso-duodenum has been utilised to afford
a covering for adjacent viscera, which are increasing in size, and are pushing
the peritoneum before them as they advance. In this particular region of the
abdomen the growth of the liver, stomach, and spleen make great demands upon
the adjacent peritoneum. As has been already said, it is evident that the growth
of the general sac of the peritoneum does not keep pace with the growth of the
structures it covers, and that it is possible for one organ to be clothed with
peritoneum at the expense of another.
To complete the account of the general relation of the peritoneum to the
intestine, the following changes remain to be noticed:-
The meso-colon. The descending colon is displaced by the growth of the rest of
1036
THE ORGANS OF DIGESTION
the bowel to the left side, and comes to occupy the position which it holds in the
fully developed body. The primitive meso-colon is displaced also to the left, and
survives as the descending meso-colon, the sigmoid meso-colon, and the meso-rectum
(fig. 599). It may be so curtailed that no distinct fold that can be called a descending
meso-colon is left, and the posterior part of the bowel is in such a case found to be
more or less uncovered by the peritoneum. The meso-rectum is a genuine and
but little disturbed relic of the simple median vertical fold of the primitive body.
The duodenum is more or less bared of peritoneum, especially so far as its third
part is concerned.
The ascending colon has, like the descending colon, been deprived of a con-
siderable amount of its peritoneum. This membrane originally belonged to the
common mesentery, but so much of it may have been abstracted from the bowel
that this part of the colon may be free from peritoneum behind, or may be con-
nected to the posterior parietes by a short meso-colon. The parietal attachments
(so-called) of this ascending meso-colon are entirely acquired, and have no relation
whatever to the primary attachment of the median fold-the primitive meso-colon-
to the posterior wall of the abdomen (fig. 599).
The mesentery. The mesentery proper-the fold belonging to the small
intestines-in like manner and by a similar process acquires a new connection with
the posterior parietes. In using the term 'new connection,' it must be understood
that the sac of the peritoneum remains quite unbroken, and that the numerous
duplicatures of the membrane have simply been so readjusted and displaced that it
has in more points than one a reflexion from the posterior wall of the abdomen.
The mesentery is described as being attached posteriorly by a very short border
which extends from the level of the attachment of the transverse meso-colon to the
left of the middle line directly down to the right iliac fossa where the ileum falls
into the cæcum' (Quain). This is the precise attachment made evident when
the intestines have been all cut away, and nothing but the stump of the mesentery
is left (fig. 599). The attachment is, however, wholly acquired or secondary, and
has been brought about by an extensive readjustment of the peritoneum. The real
attachment of the mesentery is about the origin of the superior mesenteric artery,
and this attachment obtains in mammals below man. In fig. 599 is shown the
posterior wall of the abdomen after the removal of the intestines, together with
the stomach, liver, and spleen. The lines of the various peritoneal reflexions
are depicted in a diagrammatic manner. A line drawn downwards, commencing
at the falciform ligament of the liver, and continued past the oesophagus, through
the gastro-splenic omentum, descending meso-colon, and sigmoid meso-colon,
represents the original attachment of the primitive median fold. All other lines
of reflexion must be regarded as acquired or secondary.
The meso-gaster.-It now remains to consider what becomes of the upper part
of the simple primitive fold of peritoneum-the meso-gaster (M-G, fig. 593).
The stomach enlarges, assumes more of its characteristic outline, and becomes
less vertical.
The liver may be regarded as an outgrowth from the duodenum. Its con-
nections with the great veins of the heart cause it to extend upwards and to the
right side. As it grows it separates the layers of the highest part of the peritoneal
fold, and from this membrane it receives a covering. The remains of the primitive
mesial fold persist in the form of the falciform ligament (figs. 593, 595, and 599).
The gastro-hepatic omentum.-The connection of the liver to the stomach is
intimate, partly through the association of the great gland with the duodenum, and
partly through certain blood-vessels which pass to the stomach and liver from the
aorta. As the stomach enlarges, its duodenal end is drawn towards the right side;
the viscus becomes transverse, the left wall becomes anterior, and the right posterior.
The layer of peritoneum which stretches between the two organs is called the


THE GREAT OMENTUM
1037
gastro-hepatic or lesser omentum. The right or free margin of this omentum was
originally anterior, and the whole fold is directly derived, with but little disturbance
of the membrane, from the upper part of the primitive meso-gaster (figs. 593, 595).
The great omentum.-The formation and disposition of the great omentum are
a little difficult to follow in the adult human species, and the student's conception
of the right character of this fold may be a little distorted by a study of certain
FIG. 599.-DIAGRAM TO SHOW THE LINES ALONG WHICH THE PERITONEUM LEAVES
THE WALL OF THE ABDOMEN TO INVEST THE VISCERA. (Cunningham.)

Falciform ligament Left lateral ligament
of liver
of liver
Vena cava
Gastro-phrenic
ligament
ESOPHAGUS
GASTRO-SPLENIC
OMENTUM
FORAMEN OF
WINSLOW
DUODENUM
Right
lateral
ligament of
liver
DUODENUM-
Aorta-
DUODENUM
BEHIND
PERITONEUM
Splenic artery
Costo-colic lig.
TRANS. MESO-COLON
Superior
mesenteric artery
BARE SURFACE FOR
DESCENDING
COLON
MESENTERY
BARE SURFACE-
FOR ASCEND-
ING COLON
COMMENCE-
MENT OF
COLON
BLADDER-
SIGMOID MESO-
COLON
MESO-RECTUM
diagrams which show the omentum from one point of view only. In mammals and
in the human foetus the disposition of the great omentum is readily appreciated.
This fold appears as a bulging of the meso-gaster forwards and to the left.
When the stomach has assumed its final position, this bulging of the membrane is
of course entirely in the direction forwards.
At first the great omentum forms a shallow and wide-mouthed bag. Its
1038
THE ORGANS OF DIGESTION
appearance is such as could be produced in imagination if the fingers were to be
pressed against the right (posterior) side of the meso-gaster, and were to force a
bag of the yielding membrane before them. The pendulous bag-like projection could
be seen from the left side of the meso-gaster and the wide opening into the bag
from the right (fig. 600). Here the bag is represented as cut away. An arrow
FIG. 600.-DIAGRAM TO SHOW THE FORMATION OF THE GREAT OMENTUM.

gastro-hehat. oment-
LIVER
MESENTERY
DUOD
C/ECUM
TRANS.
COLON
STOMACH
MESO.
COLON
MESO-
RECTUM
a
MESO-
CASTER
passing from right to left, i.e. from behind forwards, shows the direction of the
protrusion. The dotted line represents the position of the bag; a and p represent
sections of its anterior and posterior walls.
The bag becomes larger and larger, and more and more pendulous, until it at
last hangs down over the transverse colon and the small intestines as a kind of

FIG. 601.-GREAT OMENTUM IN MACROPUS PENICILLATUS.
DESC COLON
STOMACH
TURNED ASIDE
MESO COLON
SPLEEN
SAC OF GT. OMENTUM
CUT OPEN.
apron. Its orifice becomes narrowed in time by the growth of structures around
it, and is known as the foramen of Winslow.
If the finger be introduced into this foramen, it will touch the posterior wall of
the stomach, and consequently the right (or posterior) layer of the original meso-
gaster. As both layers of the meso-gaster enter into the formation of this pouch
or apron, it must of necessity be formed of four layers of peritoneum.

THE GREAT OMENTUM
1039
The place where the bulging takes place is a matter of importance. Originally
such part of the meso-gaster is involved in it as extends from the region of the
pylorus to about the middle of the fundus of the stomach (fig. 600).
In the lower mammals the rudimentary disposition of the great omentum is
well seen. Thus in the two-toed anteater it may be observed in its simplest possible
condition. It here takes the form of a slight bag projecting towards the left, and
formed solely by that part of the primitive meso-gaster which is nearest to the
greater curvature of the stomach. It extends to the right as far as the pylorus.
It is quite horizontal. Its greatest depth does not exceed an inch, and its orifice is
a wide shallow opening upon the right side of the meso-gaster.
In higher mammals as in some marsupials-the great omentum appears as a
loose pendulous open bag, with so large an opening that it could not be termed a
foramen. (Fig. 601 shows the great omentum in the kangaroo.)
In man and in most of the higher mammals not only is the meso-gaster
(M-G, fig. 602, A) involved in the bulging which forms the great omentum, but
some part of the transverse meso-colon (м-c) becomes involved also. This depends
upon the close connection which exists between the right end of the transverse colon
and the duodenum. It will be seen from figs. 600 and 602, A, that but a little
FIG. 602.- FORMATION OF GREAT OMENTUM AS SEEN IN VERTICAL SECTION.
A.
LIVER
STOM.
LIVER
LIVER
STOM
STOM.
B.
C.
-M-G.
-M-C.
COLON
COLON
-M-E.
S.I.
S.I.
COLON
S.I.
extension of the bulging of the membrane is needed for the transverse meso-colon
to become involved. In such case the anterior layer of the great omentum will
appear to come off from the greater curvature of the stomach, while the posterior
layer will return to the transverse colon and will become continuous with the
meso-colon (figs. 602, C, and 603, A). In the adult man this arrangement usually
extends throughout the greater part of the width of the great omentum. It is in
all instances to be observed in all that part of the great omentum which is about
and to the right of the middle line. In the foetus (as in the lower primates) the
posterior layer of that part of the great omentum which is quite to the left of the
middle line is clear of the transverse meso-colon, and is obviously derived from
the meso-gaster solely (figs. 602, B, and 603, B).
This difference between the right and the left extremities of the transverse
meso-colon and omentum can sometimes be made out in the adult man.
,
The term 'the lesser cavity of the peritoneum' is applied to the cavity formed
by this protrusion of the peritoneum. The term is of use for descriptive purposes,
but it is apt to be misleading if it favours the impression that the general sac of the
peritoneum is divided into two perfectly distinct parts.
If the diagram (fig. 562), which shows a transverse section of the abdomen at
the level of the foramen of Winslow, be examined, it will be seen that the posterior
1040
THE ORGANS OF DIGESTION
layer of the gastro-hepatic omentum, the covering of the posterior wall of the
stomach, the right layer of the gastro-splenic omentum, and the peritoneum over
the pancreas, are all derived from this so-called lesser sac of the peritoneum. If
one could imagine the stomach to be once more brought back to its original median
position, some such appearance as is shown in fig. 604 would be presented.
From this it will be seen that the gastro-splenic omentum, the coverings of the
FIG. 603.-RELATION OF GREAT OMENTUM TO TRANSVERSE COLON.


TRANS.MESO-COLON
TRANS.COLON
TRANS.COLON
GREAT
OMENTUM
A
B.
stomach, and the gastro-hepatic omentum are all derived from the original meso-
gaster, the posterior attachment of which has been shifted considerably to the left.
The left margin of the foramen of Winslow will then be seen to be the free anterior
or ventral margin of this simple primitive fold.
The gastro-splenic omentum. The spleen develops in the meso-gaster posterior
to the stomach, and the gastro-splenic omentum is but a little altered part of the
original membrane.
FIG. 604.-TRANSVERSE SECTION OF THE ABDOMEN AT THE LEVEL OF THE FORAMEN
OF WINSLOW.

STOM.
gast.hep.om
SPLEEN
gast-splen.om
AORTA
VENA
CAVA
PANCREAS
KIDN
ST.LUM.
VERT.
KIDNEY
This relation of the spleen to the meso-gaster is very admirably demonstrated
in some animals (figs. 593, 594, 595, and 601).
The duodenal fold is to be seen in the bodies of nearly all mammals below
man, excluding those somewhat lower species in which the intestinal tube remains
still as a median loop (pages 1030, 1031).
If figs. 593, 597, and 598 be examined, it will be understood that when the rotation

THE DUODENAL FOLD
1041
of the intestine takes place and the colon rises up and crosses in front of the duo-
denum, the peritoneum between the meso-duodenum and meso-colon must be folded
upon itself. The folding is V-shaped, the apex of the V being placed below, and the
plication being in or about the median line. The two membranes on a transverse
section would have the relation to one another shown in fig. 598, C.
The third part of the duodenum is brought closer to the posterior parietes; the
FIG. 605.-INTESTINE OF MACROPUS PENICILLATUS.
COLON
SUP MES ART
DUODENAL
BEND
MESO-COLON
JEJUNUM
DESC.
COLON
T
peritoneum in connection with it is curtailed; and the relations of the structures
around are readjusted As a result of these changes, which can be followed in many
of the lower mammals, a distinct fold is produced which is connected with the third
and terminal parts of the duodenum, and is often of considerable size. This fold
can be well studied in Macropus. It appears to come off from that margin of the
bowel which is immediately opposite to the attachment of the meso-duodenum
FIG. 606.-DUODENAL FOLD OF MACROPUS PENICILLATUS.
JEJUNUM
SUP MESART
DUODENUM
MESO
COLON
(figs. 605, 606). It ends below in a free edge, and posteriorly it either joins the
peritoneum on the posterior parietes close to the origin of the descending meso-
colon, or it joins the meso-colon at some little distance from the spine.
The traction about this somewhat firmly held segment of bowel has been such
that it has been drawn between the layers of its own meso-duodenum. It is by this
fold that is formed the wall of the fossa duodeno-jejunalis (page 1002, fig. 572).
3 X
SECTION IX
THE URINARY AND
REPRODUCTIVE
ORGANS
BY WILLIAM ANDERSON, F.R.C.S.
SURGEON TO AND LECTURER ON ANATOMY AT ST. THOMAS'S HOSPITAL; PROFESSOR OF ANATOMY IN THE ROYAL
ACADEMY; EXAMINER IN ANATOMY TO THE ROYAL COLLEGES OF PHYSICIANS AND SURGEONS.
THE
THE KIDNEYS
HE fundamental elements of the urinary apparatus are the kidneys-two
glandular organs situated in the loins behind the peritoneum, each of which
is provided with a duct-the ureter-for the passage of the secretion to a reservoir-
the bladder-by which it is periodically expelled from the body through a tube of
outlet-the urethra.

FIG. 607.-POSTERO-INTERNAL ASPECT OF THE LEFT KIDNEY.
Branches of the renal artery (an
irregular branch running be-
hind the duct)
Renal vein (a lower branch is
seen below the duct)
DUCT, showing superior and infe-
rior pelves with common pelvis
and commencement of ureter
proper
Physical characters.-The kidney in its typical form is bean-shaped. It is
elongated from above downwards, compressed between its parietal and abdominal
surfaces, and presents at its anterior and internal aspect a cleft, the hilum, leading
to a cavity, called the sinus, in which lie the renal vessels, nerves, and duct. The
gland in the male averages about four and three-quarter inches in length, an
inch and an eighth in thickness and weighs about five ounces. The dimensions

THE KIDNEYS
1043
of the female kidney differ little from those of the male, but its weight is from one-
seventh to one-fifth less. In the child the organ is relatively large, but its permanent
relation to the body weight is usually attained by the end of the tenth year of life.
It offers for description two surfaces, two extremities, and two borders. The
anterior or visceral surface is convex, and looks obliquely forwards and outwards;
the posterior or parietal surface, less convex than the anterior, looks inwards and
backwards; the rounded upper extremity is usually somewhat larger than the
lower, and is placed about half an inch nearer to the median sagittal plane of the
body. The external border is narrow and convex. The internal border (or surface),
looking forwards, inwards, and slightly downwards, is relatively broad, and is
fissured vertically in the middle third of its length by the hilum.
The hilum is a slit-like aperture bounded by two rounded lips of variable and
unequal thickness. The posterior lip is nearer to the middle line than the anterior,
and between the two pass the renal vessels and nerves, the duct, and a quantity of
fat-bearing connective tissue. The sinus (fig. 609), occupied by the structures just
named, is narrowest near its entrance, and about an inch in depth. Its fundus is
FIG. 608.-DIAGRAM SHOWING RELATION OF KIDNEY TO CAPSULE.
TRANSVERSE COLON
DESCENDING COLON
PERITONEUM
FATTY CAPSULE-
CUT EDGE OF
PERITONEUM
Muscular fibre in
subperitoneal
tissue
PANCREAS
Sup. mesenteric vein
DUODENUM
Vena cava
KIDNEY
PERITONEAL CAVITY
Diaphragmatic/
fascia
Parietal muscle
SUBPERITONEAL TISSUE FATTY CAPSULE Renal vessels embedded in subperitoneal tissue
LYMPHATIC GLAND
LUMBAR VERTEBRA
pierced by the renal vessels and nerves, and by the uriniferous tubules; and gives
attachment to the primary branches (calices) of the duct.
Investment and fixation. The entire organ is enveloped and supported by a
kind of capsule of fat-bearing connective tissue derived from the parietal layer of
the subperitoneal fascia (fig. 608). The adipose element may be in large or small
quantity. In the latter case the investment often appears as a transparent fascial
plane, which in renal operations may be mistaken for peritoneum, or fascia trans-
versalis; or, if the fat be excessively developed, it may form a kind of hernial
protrusion into the parietal incision. Should the sustentacular power of the fatty
capsule become impaired from any cause, the phenomenon of movable or wandering
kidney is established, the organ tending to shift its place as far and in such
direction as the attachment of its vessels to the main trunk will permit. A partial
covering of peritoneum is loosely adherent to its anterior surface.
Position and relations. The kidney is commonly said to lie in the lumbar
3x2
1044
THE URINARY ORGANS
region. It is, however, intersected by the horizontal and vertical planes which
separate the hypochondriac, lumbar, epigastric, and umbilical regions from each
FIG. 609.-SECTION OF KIDNEY, SHOWING THE SINUS. (After Henle.)

CORTEX PROPER
Vessels
BOTTOM OF SINUS
ATTACHMENT OF CALYX
APEX OF PAPILLA WITH
ORIFICES OF URINI-
FEROUS TUBULES
BOTTOM OF SINUS
MARGIN OF HILUM
TWO PAPILLE SUR-
ROUNDED BY A
SINGLE CALYX
FIG. 610.-DIAGRAM OF RELATIONS OF THE POSTERIOR SURFACE OF THE KIDNEY.
(The diaphragmatic area usually extends lower than this on the left side, and the eleventh
rib may come into indirect relation with its upper end.)

OUTLINE OF 12TH RIB
Diaphragm
Transversalis
P
soas
TRANSVERSE PROCESSES OF THE FIRST
AND SECOND LUMBAR VERTEBRÆ

LINE INDICATING OUTER BORDER OF
QUADRATUS LUMBORUM
belongs to all these segments of the abdominal space. Its
b said to correspond to the last thoracic and two upper
lumbar
THE KIDNEYS
1045
vertebræ, the right lying in most cases from a third to half an inch lower than the
left, but exceptions to this rule are not infrequent.
The posterior surface (figs. 610, 611), with the corresponding portion of the
fatty capsule, rests against the posterior abdominal wall in front of the eleventh and
twelfth ribs and the transverse processes of the first and second lumbar vertebræ ;
the left kidney usually reaching as high as the upper border of the eleventh rib,
the right only to its lower border. The only visceral relation posteriorly is on the
left side, where the spleen slightly overlaps the kidney opposite the upper half of its
outer border. The parietal relations on both sides are as follow: (1) the diaphragm;
FIG. 611.-THE ABDOMINAL VISCERA, SEEN FROM BEHIND.
(From the model of His.)
The kidneys are somewhat lower than usual in their relations to the ribs.

LUNG
SUPRARENAL BODY
LOBUS SPIGELII OF
LIVER
Aorta
OUTLINE OF LAST RIB
SPLEEN
LEFT KIDNEY, WITH.
SUPRARENAL BODY
DUODENUM
COLON.
CUT EDGE OF
PERITONEUM
OUTLINE OF LAST RIB
Vena cava
RIGHT KIDNEY, WITH
URETER INTERNALLY
SMALL INTESTINE
OUTLINE OF ILIAC
CREST
OUTLINE OF ILIAC
CREST
COLON
-PARIETAL PERITONEUM
WITH COLIC VESSELS
FIRST PORTION OF
RECTUM
SIGMOID FLEXURE
SECOND PORTION OF.
RECTUM
BLADDER
BLADDER
AMPULLA OF RECTUM
CÆCUM
SMALL INTESTINE
(2) the anterior lamella of the posterior aponeurosis of the transversalis (separating
the organ from the quadratus lumborum); (3) the psoas; (4) the three fascia-
diaphragmatic, transversalis, and iliac -which line these muscles respectively; and
(5) the last thoracic, the ilio-hypogastric, and the ilio-inguinal nerves, and the anterior
divisions of the first and second lumbar vessels, all running obliquely downwards
and outwards in front of the quadratus lumborum to pierce the transversalis beyond
the outer border of the quadratus. Owing to the higher level of the left kidney,
its diaphragmatic area of contact is larger than that of the right organ. This
area moreover, may be increased on either side when the arcuate ligaments
1046
THE URINARY ORGANS
which give origin to a large portion of the posterior fibres are attached to the tip
of the transverse process of the second lumbar vertebræ instead of that of the first.
The pleura has an indirect but important relation to the kidney. The inferior
limit of the pleural sac extends almost horizontally outwards from the lower border
of the twelfth thoracic vertebra, crossing the last rib near its neck, and the eleventh
rib about two inches farther outwards. As a rule, the incision in renal operations
may be carried safely to the lower border of the last rib; but, should this bone be
absent or very short, the eleventh rib may be mistaken for it, and the serous
membrane would then be in danger. It is probable too that the pleura reaches
to a lower point in those cases where the arcuate ligaments are attached to the
second lumbar transverse process. The presence of a thirteenth rib would involve
a contraction of the space available for the surgical exploration of the organ.
The upper extremity of each kidney is crowned by the suprarenal body (fig. 611,
612), which encroaches also upon its anterior surface and inner border, and is fixed
to it by connective tissue derived from the subperitoneal fascia.
The anterior or visceral surface (fig. 612) is differently related on the two sides.
FIG. 612.-DIAGRAM SHOWING ANTERIOR RELATIONS OF KIDNEYS AND
SUPRARENAL BODIES.

DUODENAL AREA HEPATIC AREA
GASTRIC AREA
(NON-PERITONEAL) (NON-PERITONEAL) CAVAL AREA (PERITONEAL)
HEPATIC AREA
(PERITONEAL)
DUODENAL AREA
(NON-PERI-
TONEAL)
COLIC AREA
(NON-PERI-
TONEAL)
MESO-COLIC AREA
MESO-COLIC AREA
GASTRIC AREA
OF SPLEEN
- Splenic artery
PANCREATIC
AREA (NON-
PERITONEAL)
COLIC AREA OF
SPLEEN
COLIC AREA
(NON-PERI-
TONEAL)
The right kidney is in contact in about its upper half with the renal impression on
the liver (page 1015), and below with the ascending colon and duodenum; the hepatic
area being covered with peritoneum, while the second stage of the duodenum
and more externally the ascending colon are directly attached to the surface by
subperitoneal tissue; but the two non-peritoneal areas vary considerably in their
relative proportions, not only in different subjects, but in the same subject under
different conditions of distension of the duodenum and the colon. The second
stage of the duodenum is also more or less in relation with the right renal vessels.
The left kidney lies behind the stomach, the pancreas, the splenic vessels, the
descending colon, and the colic vessels. Its anterior surface may be divided into
three portions: an upper or gastric area, separated from the stomach by the
peritoneum of the lesser sac; a middle or pancreatic area, attached to the pancreas
by subperitoneal connective tissue, and crossed also by the splenic vein where this
vessel lies behind the upper border of the gland, and by the splenic artery, which
runs in a serpentine course immediately above the vein; and an inferior or colic
area, the outer portion of which is covered by the splenic flexure and upper part

THE KIDNEYS
1047
of the descending colon; the inner by a layer of peritoneum (of the greater sac)
and the colic vessels.
The outer border of the kidney reaches a point about three and a half or four
inches external to the lumbar spinous processes. On the right side, it is in contact
with the liver in its upper half or two-thirds; on the left, its upper third or half rests
against the renal groove in the posterior portion of the visceral surface of the spleen.
The inner border of the right kidney lies close to the vena cava, especially above;
that of the left is divided from the aorta by an interval of an inch or more.
The position of the kidneys at the back of the abdominal cavity involves a
certain amount of pressure upon the organs and their vessels and nerves by the
weight of the viscera in front when the body is supine, and there is reason to
believe that their secretory functions are consequently influenced by changes of
posture to an extent that may be utilised in therapeutics.
The structures lying within the sinus are the renal artery and vein, the renal
lymphatics (vessels and glands), a plexus of nerves, the duct, and more or less con-
nective and adipose tissue continuous with the fatty capsule. The renal artery
is a branch of the aorta given off opposite the first lumbar vertebra and behind the
pancreas. On reaching the hilum it breaks up into four or five branches, which
generally lie directly in front of the duct, and behind the vein; but irregular vessels
may pierce the gland above or below the hilum, and a branch of the artery not
infrequently passes immediately behind the duct (fig. 607). The left renal vein
receives the spermatic or utero-ovarian vein, and is usually somewhat lower than
the right. The shortness of the right renal vein should be remembered in the
operation of nephrectomy.
Structure. The kidney when removed from its fatty investment is seen as a
yellowish-red organ covered by a thin but strong fibrous capsule (tunica propria),
which is prolonged through the hilum into the sinus, where it becomes continuous
with the sheaths of the renal vessels, and extends as far as the attachments of
the subdivisions of the duct around the renal papillæ. The whole capsule may
be easily peeled off from the healthy kidney, except at the bottom of the sinus
where it is fixed by the vessels and duct; and as the capsular vessels are of small
size, the process of stripping is attended with little hæmorrhage when practised
in the course of operations upon the living subject.
On section through the hilum the renal parenchyma is found to be made up
of two structural elements, the medulla and the cortex; the former consisting
of a variable number (eight to eighteen) of conical segments called pyramids of
Malpighi, the apices of which project into the bottom of the sinus (fig. 609) and are
surrounded by the primary segments (calices) of the duct, while their bases are
turned towards the surface, but are separated from it and from each other by
the cortex. The pyramids average in their axial diameter about three-quarters
of an inch, and have a width at the base of about two-thirds of an inch. They
are smooth and somewhat glistening in section, and marked with delicate striæ
which converge from base to apex, and indicate the course of the uriniferous
tubules. The blunted apex, or papilla, single or in association with one or even
two of its fellows, is embraced by a calyx, and if examined with a hand lens will
be seen to present forty or fifty minute apertures, the foramina papillaria, through
which the secretion escapes into the duct.
The cortex may be divided into two portions: a peripheral layer, the cortex
proper, which is a little less than half an inch in thickness, and extends from the
capsule to the bases of the pyramids of Malpighi; and processes called columnæ
Bertini, which dip inwards between the Malpighian pyramids to reach the bottom
of the sinus, where they are covered by the fibrous capsule and more or less adipose
tissue (fig. 613). In section the cortex is somewhat granular in aspect, and in an
injected kidney is seen to be dotted with minute points corresponding to vascular
1048
THE URINARY ORGANS
glomeruli lying within the cæcal origin of the uriniferous tubules (capsules of
Bowman). Examined more closely, it displays a number of small pyramidal
groups of tubules, some belonging to the cortex proper, with their bases resting
upon the bases of the Malpighian pyramids, the apices directed towards, but not
reaching, the periphery; others forming a part of the columnæ Bertini, and
disposed almost at right angles to the last. These cortical groups are called
pyramids of Ferrein, in contradistinction to the much larger medullary pyramids
of Malpighi.
The kidney of a foetus differs from that of the adult in the lobular subdivision
of its surface, each lobule corresponding to the base of a pyramid of Malpighi
capped by a thin layer of cortex. Such a condition is permanent in some of the
lower animals; but in man the superficial indications of morphological segmenta-
tion usually become obliterated during the progress of growth of the cortical tissue,
and are seldom visible after the age of ten. is sit nidhy
Uriniferous tubes (fig. 614).-The secreting tubules commence by a number
of spherical capsules (capsules of Bowman), which lie in the cortex. From each
ided
da
FIG. 613.-HORIZONTAL SECTION OF KIDNEY, SHOWING THE SINUS.

CORTEX WITH CAPSULE-
COLUMN PYRAMID Cortico-
OF
OF medullary
BERTINI
MALPIGHI artery Artery
ban (2009a)
Branch DUCT Portion
of fatty
of
capsule
artery
Irregular
branch
of artery
io
iqlal
capsule passes a tube with a narrow neck, which becomes wide and convoluted,
then, narrowing again, runs down into the subjacent Malpighian pyramid, forms
a loop (looped tube of Henle), returns into the cortex, where it again becomes
dilated and contorted, and, after undergoing a final constriction, opens into a
straight collecting tube, the axial element of a pyramid of Ferrein. The collecting
tubes run into the Malpighian pyramids, unite with each other to form a smaller
number of larger tubes, which terminate by opening on to the papillary apex of the
pyramid, and into the corresponding calyx of the duct. The tubes are lined with
epithelium throughout, the cells being tesselated in the capsule, irregularly cubical
in the convoluted tubes, flattened on the loops of Henle, and columnar in the
cortical collecting tubes and in the straight tubes of the medulla.
Vessels (fig. 614). The kidney is very vascular. The larger arterial branches, if
traced in section from the point at which they pierce the bottom of the sinus, will
be found to run up between the pyramids of Malpighi to subdivide at their
bases into cortico-medullary arches which lie between the cortex and medulla,


THE KIDNEYS
1049
giving off arterioles in both directions, the cortical branches supplying afferent
twigs to the glomeruli within the capsules of Bowman; the medullary branches
running inwards to form plexuses around the straight and looped tubules of
the Malpighian pyramids. The efferent vessels of the Malpighian glomeruli form
a capillary plexus around the uriniferous tubules and terminate in the renal veins.
The surface of the kidney receives small collateral arteries which pass through the
FIG. 614.-SCHEME OF TUBULES AND VESSELS OF THE KIDNEY. (After Macalister.)
TUNI CA PROPRIA
Cortical vein.
PRIMARY CONVO-
LUTED TUBE
Glomerulus and.
capsule of
Bowman
CORTEX-
Cortical vein
Cortico-medullary.
artery
Medullary artery.
Efferent vessel form-.
ing medullary
plexus
CAPSULE OF BOWMAN
SECONDARY CONVO-
LUTED TUBE
MEDULLA-
LOOPED TUBE OF
HENLE
Papillary plexus
surrounding the
foramina papil-
laria
ULTIMATE TUBE
OPENING ON TO
THE FORAMEN
PAPILLARE
fatty capsule from the suprarenal, spermatic, and lumbar vessels. The superficial
veins appear in the form of little stellate groups (stars of Verheyen), which are
very distinct when the organ is congested. The renal lymphatics may be divided
into two sets, capsular and parenchymatous. They terminate in a series of glands
lying with the renal vessels in the subperitoneal tissue, and their contents are
ultimately conveyed into the receptaculum chyli.
Nerves.-The nerves form a plexus accompanying the vessels, and are derived
1050
THE URINARY ORGANS
mainly from the sympathetic through the solar and aortic plexuses, the semilunar
ganglia, and the splanchnics. They communicate with the spermatic plexuses.
Some filaments have also been traced from the pneumogastrics.
Varieties. The principal variations of the kidney are as follow:-
1. In form.-Disproportionate increase of one or other diameter, producing
the long, globular, and discoid types.
2. In size.-Inequality: one being small, the other compensatingly large.
3. In number. The organ may be single, then usually occupying its ordinary
position in one or other loin; or, still more rarely, it may be triple, in which case
the additional gland is either lateral or median.
4. In position. One or both kidneys may be above or below the normal level,
in the latter and far more frequent case encroaching upon the iliac fossa, or even
entering the true pelvis in front of or behind the rectum; or the displacement may
be horizontal, the organ lying upon the vertebral column or even in the opposite loin.
5. By fusion of the two kidneys; the union involving the lower extremities only
(horseshoe kidney '), or the whole length of their inner borders.
6. In mobility. Undue mobility is usually, if not always, due to a laxity of
that portion of the subperitoneal tissue which constitutes the fatty capsule; but
a peritoneal meso-nephron is said to have been seen in extremely rare cases of
movable kidney.
THE SUPRARENAL BODIES
These structures do not form any part of the genito-urinary apparatus, but it
is convenient to describe them in association with the glands by which they are
supported.
The suprarenal bodies (fig. 615) are two solid viscera resting each upon the
upper extremity of the corresponding kidney and the adjoining parts of its inner and
anterior surfaces, and bound to it by subperitoneal connective tissue. They lie
against the diaphragm opposite the eleventh rib, or tenth intercostal space, and are
separated from each other by a space of about two inches and a half. The left is
usually a little higher than the right owing to the greater elevation of its kidney.
The organ varies widely in dimensions within physiological limits. Its average
weight is about a drachmi, its height an inch and a quarter, and its greatest breadth
at the base an inch and three-quarters.
The right suprarenal body is pyramidal in form with the apex directed upwards
and somewhat inwards. Its anterior surface is related above to a special impression
upon the under and back part of the right lobe of the liver, between the layers
of the coronary ligament; internally to the inferior vena cava which slightly
overlaps it (Rolleston); and below is covered with peritoneum continuous with
that of the kidney, except at its internal inferior angle where it is crossed by the
hepatic flexure of the duodenum. It is rather firmly adherent to the liver, and the
vessels of the two organs anastomose with each other at this point.
The left suprarenal body is a little larger than its fellow, somewhat crescentic
in shape, and encroaches less upon the summit of the kidney than the right, and
more upon the inner border, reaching even to the hilum. Its anterior surface is
covered above by the peritoneum of the lesser sac, which separates it from the
stomach; and below, near its internal inferior angle, it is crossed by the upper
border of the pancreas and the splenic artery. Externally it is in contact with
the upper extremity of the spleen, which passes a little behind it, and its inner
border is separated from the aorta by the fibres of the diaphragm.
Accessory suprarenal bodies are often present in the connective tissue around the
principal organ.
Structure. On section the organ is found to be covered by a thin fibrous


THE SUPRARENAL BODIES
1051
capsule which sends trabecular processes between the cellular elements of its
proper substance. The parenchyma consists of a peripheral portion, or cortex, of
yellowish colour, except in its deepest layer which is darkly pigmented, and a
central portion or medulla, soft and greyish, and tending to break down under
decomposition in such a manner as to give the appearance of an irregular cavity
(whence the name suprarenal capsule').
Vessels and nerves.-It is richly supplied both with vessels and nerves. Its
arteries are derived from three sources-the aorta, the phrenic, and the renal-and
pierce the organ in various places. The veins terminate on the right side in the
vena cava, and sometimes by means of small branches in the phrenic and renal
trunks; on the left, in the left renal vein. The lymphatics pass to the renal
glands, which, like the suprarenal bodies, themselves contain a good deal of
pigment. The nerves come from the solar plexus, and include filaments from the
sympathetic, the splanchnics, and according to some authors from the phrenic and
vagus also. It is disproportionately large in early foetal life, and has nearly reached
its full growth at the time of birth.
FIG. 615.-DIAGRAM SHOWING RELATIONS OF THE KIDNEYS AND
SUPRARENAL BODIES.
DUODENAL AREA HEPATIC AREA
GASTRIC AREA
(NON-PERITONEAL) (NON-PERITONEAL) CAVAL AREA (PERITONEAL)
HEPATIC AREA
(PERITONEAL)
DUODENAL AREA
(NON-PERI-
TONEAL)
COLIC AREA
(NON-PERI-
TONEAL)
MESO-COLIC AREA
MESO-COLIC AREA
GASTRIC AREA
OF SPLEEN
Splenic artery
PANCREATIC
AREA (NON-
PERITONEAL)
COLIC AREA OF
SPLEEN
COLIC AREA
(NON-PERI-
TONEAL)
THE RENAL DUCTS
The excretory duct of the kidney (figs. 607, 611, 616) is a musculo-mucous canal,
expanded and irregularly branched above, narrow and of fairly uniform dimensions
in the rest of its course. At its origin in the sinus renalis it appears in the form
of a number of short tubes, usually eight or nine, called calices, each of which
embraces the papillary extremity of a pyramid of Malpighi two or three lines above
its apex, or occasionally two papillæ may be connected with a single calyx. The
calices average about a third to half an inch in length, and open directly or by
means of intermediate tubes (infundibula) into two short passages, the superior
and inferior pelves, which in turn combine after a longer or shorter course to form
the common pelvis. The inferior and larger pelvis has a diameter of about two-
fifths of an inch; the superior is about one-third less. The common pelvis varies
greatly in different subjects. It usually appears as a more or less funnel-shaped
portion of the canal, wider above (about three-fifths of an inch), where it lies
between the two lips of the hilum; narrow below, where it arches downwards
and inwards to become continuous with the relatively uniform portion of the duct
1052
THE URINARY ORGANS
known as the ureter proper. In some cases, however, it can scarcely be said to
exist as a dilatation.
Under ordinary circumstances it is flattened from before backwards, its anterior
and posterior walls being in contact, and its channel represented by a fissure. It
is in relation behind with the posterior lip of the hilum, from which it is separated
by more or less adipose tissue continuous with the fatty capsule, and occasionally
by an irregular branch of the renal artery. The renal vein and artery imbedded
in fat lie in front, and anterior to these structures are situated the descending
portion of the duodenum on the right side, and the pancreas on the left.
The ureter extends from the termination of the pelvis to the bladder, running
in a kind of lymph-space between the laminæ of the subperitoneal tissue. It is
a tube of about a sixth of an inch in diameter when distended, and is fairly
uniform in size, except about two inches below the kidney where a slight constric-
tion is usually found (Bruce Clark). Its length is variously stated, but the average
in the male adult may be taken as about twelve inches. The excessive estimates
sometimes given depend upon the untrustworthy indications afforded by admeasure-
ment after the removal of the structure from the body.
FIG. 616.-UPPER PORTION OF DUCT. (After Henle.)

CALYX-
INFUNDIBULUM
SUPERIOR PELVIS
COMMON PELVIS
CALYX
URETER-
INFERIOR PELVIS
Course and relations.-The tubes lie about three inches apart at their commence-
ment, but this distance gradually lessens to about two inches as they descend
towards the sacro-iliac joint. In the true pelvis they at first diverge, but finally on
nearing the base of the bladder run forwards and inwards to pierce the wall of the
viscus, and at their termination are separated by a distance of about an inch and a
quarter. The course of each tube may be conveniently divided into three stages,
abdominal, pelvic, and vesical. The abdominal portion, running downwards and
slightly inwards, is in relation, posteriorly, with the psoas and its fascia, and
the genito-crural nerve, and with the common iliac artery near its bifurcation.
Anteriorly, it is covered by peritoneum and intestines, and is crossed by the
colic and spermatic vessels. Internally, it is opposed on the right side to the
inferior vena cava, on the left to the aorta; the vein being almost in contact
with the right ureter, while the artery is separated from the left tube by an
interval that gradually diminishes from one inch above to half an inch opposite
the bifurcation of the vessel.
The pelvic portion runs in front of the sacro-iliac synchondrosis then the


upon

THE RENAL DUCTS
1053
obturator internus and its fascia behind and below the psoas, finally leaving the
pelvic wall to join the bladder. In this position, in the male it is crossed superiorly
and internally by the vas deferens, and lies under cover of the free extremity of the
vesicula seminalis, separated from its fellow by a distance of an inch and a half.
In the female it runs parallel with, and four to six lines from the cervix uteri, behind
the uterine artery, through the uterine plexus of veins, and beneath the root of the
broad ligament; finally crossing the upper third of the vagina to reach the vesico-
vaginal interspace and pierce the bladder opposite the middle of the vagina. A
calculus in the lower end of the tube might be detected by a vaginal examination.
The vesical portion, about half an inch in length, runs obliquely downwards
and inwards through the coats of the bladder, and opens on to the mucous surface
at a distance of about three-quarters of an inch to an inch from its fellow, and from
the internal urinary meatus.
Structure. The wall of the ureter is about a twenty-fifth of an inch in thickness,
and consists of a mucous membrane, a muscular coat, and an external connective
tissue investment. The mucous membrane is longitudinally plicated, and is lined
with a multiple layer of transitional epithelium, continuous with that of the papillæ
above, and with that of the bladder below. Mucous follicles are said to exist in the
pelvis renalis. The muscularis is about one-fiftieth of an inch in thickness, and
consists of two layers, an external composed of annular fibres, an internal of fibres
longitudinally disposed. After the tube has entered the bladder the circular fibres
appear as a kind of sphincter around its vesical orifice; while the longitudinal
fibres spread out to form with those of the opposite side a triangular expanse with
its apex at the internal urinary meatus and its base corresponding to a line drawn
between the two ureteric orifices.
Vessels and nerves.-The arteries of the ureter come from the renal, spermatic,
internal iliac, and vesical; the veins terminate in the corresponding trunks; and
the lymphatics pass to the pelvic and lumbar glands and into the receptaculum
chyli. The nerves are supplied by the spermatic, renal, and hypogastric plexuses.
Varieties. The most important variation consists in the partial or complete
duplication of the tube owing to the late union or to the non-union of the superior
and inferior infundibula or pelves. In rare cases the calices form three pelves
which may in like manner remain separate in part or in the whole of their course
to the bladder.

THE BLADDER

The urinary bladder is a receptacle, of which the form, size, and position vary
with the amount of its contents. The adult organ in its empty or moderately
filled condition lies entirely below the level of the oblique plane of the pelvic inlet ;
but when considerably distended it rises into the abdomen and shows itself beneath
the parietes as a characteristic mesial projection above the symphysis; a projection
which in certain cases may extend nearly to the level of the umbilicus. It is
invested over its whole extent by recto-vesical fascia, and is partially covered above
by peritoneum (fig. 617).
Form. When fully distended it assumes in the male an ovoid shape with its
longest diameter directed downwards and backwards, but in women the transverse
diameter is commonly the greatest. In the child it is somewhat pear-shaped, the
stalk being represented by the urachus.
The form of the empty bladder is still doubtful, as the appearances in the dead
subject do not necessarily coincide with the condition existing during life. In
1054
THE URINARY ORGANS
mesial sagittal section it usually appears somewhat cup-shaped, its upper wall
presenting a rounded or pyramidal hollow to the intestines, while its cavity is
represented by a T or Y-shaped fissure (as in plate 1 of Symington's ' Anatomy of
the Child'). It is possible that this diastolic' form, as it has been termed, is the
normal result of a relaxation preliminary to refilling; but it appears more probable
that it is due to the loss of vital elasticity of the muscular wall, and that the
healthy living bladder always maintains a rounded or ovoid form.
TRANSVERSE COLON
FIG. 617.-MEDIAN SAGITTAL SECTION OF THE MALE PELVIS.
(From a preparation in the Museum of St. Thomas's Hospital.)

SMALL
INTESTINE
BLADDER-
SYMPHYSIS-
Prostatic
venous
plexus_
CORPUS
CAVERNOSUM
PROSTATE
Triangular-
ligament
PENILE-
ANGLE
BULB
URETHRA
TESTICLE
RECTUM
Sphincter ani
-FIRST SACRAL
VERTEBRA
SIGMOID
FLEXURE
SMALL
INTESTINES
COCCYX
RECTO-VESICAL
POUCH WITH
ADIPOSE FOLD
The three terms, apex' or 'superior fundus,' 'inferior fundus,' and 'neck,' are
commonly applied to parts of the bladder: the first to the point of attachment of the
superior ligament or urachus (a relic of the tube of communication between the
bladder and allantois) which connects it with the umbilicus; the second to the lower
part of the organ, and the third to the point at which the vesical cavity becomes
continuous with the urethra; but the expressions are all more or less objectionable,
and serve no useful purpose. Under ordinary distension the so-called apex' is.
as much rounded as the rest of the viscus; the anatomical limits of the 'inferior
fundus' are still undefined; and the only neck' that can be assigned to the bladder
is represented by the prostate and prostatic urethra.
'
Relations. The bladder when moderately filled may be said to present for
description five aspects or surfaces: antero-inferior or pubic, posterior or rectal,
superior or intestinal, and two lateral or obturator surfaces. The anterior, posterior,

THE BLADDER
1055
and lateral surfaces meet above at the urachus, and converge below towards the base
of the prostate-the posterior wall sometimes approaching the urethral orifice almost
in a vertical direction, as in Braune's section (plate 2), or curving first downwards,
and then forwards, as in fig. 617; and in old subjects this curve may be so exagge-
rated that a kind of pouch is formed behind the internal meatus. The antero-inferior
surface looks downwards and forwards towards the symphysis. It is uncovered by
peritoneum, but has a strong investment of recto-vesical fascia, and is separated from
the pubic bones and anterior attachments of the obturatores interni and levatores
ani by a space known as the cavum Retzii, which contains a variable quantity of
loose fat continuous with the pelvic and abdominal subperitoneal tissue. Each
lateral surface is covered by peritoneum down to the level of a line extending from
the urachus backwards to a point below the summit of the vesicula seminalis, about
an inch above the base of the prostate. Below this level it is separated from the
levatores ani by subperitoneal tissue, which usually bears much fat in its meshes
and ensheaths the vesical vessels and nerves; and it is crossed by the vas deferens,
and at the point of peritoneal reflexion by the obliterated hypogastric artery. The
ureter pierces the junction of the posterior and lateral surfaces about two inches
above the prostate, the vas running between it and the vesical wall. External to
these structures the lateral wall is in relation to the levator ani and obturator internus.
The posterior surface may be divided into two portions, an upper covered by the
peritoneum of the recto-vesical or utero-vesical pouch, a lower in direct contact with
the anterior wall of the rectum, and the lower part of the vasa deferentia and vesiculæ
seminales. The distance of the recto-vesical cul-de-sac of peritoneum from the
prostate is very variable, but usually ranges between half an inch and one inch, and
may be increased to two inches by distension of the bladder. It is, however, very small
in the child. The ureters where they lie at the outer limits of this surface are near
to though not in contact with the rectum, and a calculus in the lower end of the
urinary tube might be felt by an exploration from within the bowel. In the lower
portion of the posterior wall in the male is a triangular space, the sides of which
are formed by the diverging vasa deferentia, the base by the line of reflexion of
the recto-vesical pouch of peritoneum, and the apex by the meeting of the ejacula-
tory ducts at the summit of the prostate. It was formerly selected as the position
for the introduction of a trocar through the rectum into the bladder in cases of
retention of urine. In the female the posterior surface is adherent below to the
cervix uteri and upper part of the anterior wall of the vagina, but is separated
above from the body of the uterus by a shallow utero-vesical pouch of peritoneum.
The superior surface is entirely covered with peritoneum. It looks almost
directly upwards into the abdominal cavity, and lies in contact with the small
intestines, and sometimes with a portion of the sigmoid flexure behind these.
Effects of distension.-When the bladder becomes excessively full it rises above
the level of the symphysis, and in certain chronic conditions of retention may even
mount as high as the umbilicus. During the process of distension the anterior wall
carries upwards the peritoneal fold reflected on to its upper surface. This elevation is,
however, variable and limited in extent; at its maximum it seldom exceeds two inches,
and in some instances fails even to pass the upper border of the symphysis, hence
there is some danger in tapping the bladder above the pubes unless the part is exposed
by a careful dissection. In recent years Garson and Pietersen have demonstrated
that the introduction into the rectum of a bag of suitable dimensions filled with air
or water pushes forward the expanded viscus and may still further increase the
available space for surgical operation, but it does not ensure the elevation of the
peritoneal fold above the symphysis.
The relation of the internal urinary meatus to the pelvic wall has become a
subject of interest since the revival of suprapubic operations upon the bladder. As
a rule it lies at some point opposite the upper half of the symphysis, but in great
1056
THE URINARY ORGANS
distension of the viscus (see Rüdinger, plate 3) it may descend to a lower level.
On the other hand, in young children it usually reaches the level of the upper
border of the symphysis, and in old persons with prostatic disease it may rise even
above this point. In the male adult it lies from three-quarters of an inch to an
inch behind the symphysis, and about two or two and a half inches above the
perinæum.
Structure. The bladder wall is composed mainly of unstriped muscular fibre,
invested externally by a layer of recto-vesical fascia and a partial covering of
peritoneum, and lined with mucous membrane and submucous tissue. Its thick-
ness varies greatly in different subjects and in the same subject under different
conditions of distension. It is estimated at about an eighth of an inch when
moderately stretched, but may reach half an inch or even more when completely
contracted. It is somewhat thicker at the trigone.
The arrangement of the peritoneum over the superior, lateral, and posterior walls
has been described, and it only remains to mention that its reflexions over the
urachus above, and from the sides and back of the bladder below, form the superior,
lateral, and posterior false ligaments. The recto-vesical fascia is a well-developed
FIG. 618.-THE POSTERIOR WALL OF THE BLADDER. (After Henle.)

VAS DEFERENS
URETER PIERCING-
VESICAL WALL
PLICA URETERICA
VESICAL APERTURE OF
URETER
MUSCULARIS
MUCOSA
UVULA OF LIEUTAUD
VERUMONTANUM
OPENING OF EJACULATORY DUCT-
SINUS POCULARIS-
PROSTATIC SINUS-
PROSTATE-
hod
layer of tissue over the lower part of the viscus, but is greatly attenuated above. It
is continuous below with the capsule of the prostate, and passes on to the pubic
bones in front of the latter organ in the form of a double fold called the pubo-
prostatic or anterior true ligaments, and upon the levator ani at the sides, where
its reflexions are termed the lateral true ligaments, while the urachus above
represents a superior ligament. These traditional names, however, are misleading
and have no practical value. The muscular coat is composed of unstriped fibres
which may
be divided roughly into two layers, an outer principally longitudinal
and an inner plexiform, but tending towards the horizontal direction. The fibres
of the outer layer are most distinctly longitudinal on the anterior and posterior
surfaces, and extend above along the urachus, but they run obliquely over the sides of
the bladder, decussating with each other in a complex manner; and near the urethral
end of the viscus two strong bundles of the anterior longitudinal fibres run one
on each side of the middle line in front of the anterior wall of the prostate and
beneath the pubo-prostatic ligament, to become attached to the back of the pubic
bones on each side of the symphysis (vesico-pubic muscle). The inner layer forms a
kind of annular sphincter near the urethral orifice (sphincter vesica internus), the
fibres of which are continuous with the upper sphincteric fibres of the prostate, and

THE BLADDER
1057
at the trigone are reinforced by the expansion of the longitudinal ureteric fibres
named on page 1053.
The rather coarse meshwork formed by the decussating muscular fibres is apt
to present weak points through which the mucous membrane may protrude as
diverticular sacculations, sometimes of considerable size and capable of lodging
calculous concretions. On the other hand, when the muscular tissue becomes
hypertrophied from excessive use, it often forms strong ridge-like projections which
may give rise to deceptive impressions during exploration of the cavity with the
sound.
FIG. 619.-SECTION OF THE FEMALE PELVIS. (After Henle.)

SYMPHYSIS-
PERITONEUM-
VESICAL WALL-
CAVITY OF
BLADDER
Prevesical fat-
Dorsal vein.
CLITORIS
Deep trans-
versus perinæi
UTERUS
RECTUM
COCCYX
Recto-coccy-
geal muscle
POSTERIOR LIP
OF OS UTERI
ANTERIOR LIP
VAGINA
External
-sphincter ani
Internal
sphincter ani
LABIUM MAJUS
Unstriped muscular fibre
URETHRA
LABIUM MINUS
Unstriped muscular fibre
Vessels
VAGINAL ORIFICE
ANUS
BRIAN THT
Part of external sphincter ani
Internal sphincter ani
The submucous coat consists of a highly elastic connective tissue devoid of
muscular fibres.
The mucous membrane is smooth, soft, and rose-coloured during life. In the
empty bladder it is thrown into irregular folds, which become effaced by distension.
It is modified posteriorly over a triangular area called the trigone (fig. 618), the
three angles of which lie at the internal meatus and the two ureteric orifices, and are
at a distance from each other of three-quarters of an inch to an inch. This region,
which lies opposite to the second stage of the rectum, is free from the plication
that appears in the rest of the mucous membrane during contraction of the cavity,
and presents a transverse elevation between the ureters, called the plica ureterica,
3Y
1058
THE URINARY ORGANS
and a longitudinal mesial ridge, the uvula of Lieutaud, near the urethral orifice.
It is smaller and less distinct in the female. The internal urinary meatus usually
lies at the most dependent part of the bladder, but in morbid conditions of the
prostate the borders of the aperture may be considerably elevated above the adjacent
vesical zone.
The female bladder (fig. 619) presents no peculiarities of importance, except that
its frontal diameter is usually increased at the expense of the sagittal diameter, partly
in consequence of the greater width of the pelvis, and partly owing to the presence
of the vagina and uterus, which encroach upon the space in the middle line.
Lateral asymmetry is very common. Furthermore, the symphysis being of less
depth than in the male, the urinary orifice lies nearer its lower border.
In the infant the bladder is said to be an abdominal organ, but this is not strictly
accurate. The relatively small pelvic cavity at this period of life is occupied mainly
by the rectum, and there is little room for the bladder, which hence rises into the
abdomen even in moderate degrees of distension; but, as pointed out by Symington,
if a line be drawn from the sacral promontory to the top of the symphysis, fully one
half of the bladder will be found to lie below it, and hence within the pelvis. The
internal meatus, however, is behind the upper margin of the symphysis, and the
whole organ is hence above the horizontal level of the pubic crests. This relation
gradually changes from the period at which independent locomotion begins, till by
the age of six, when the pelvic wall has grown up around the viscus, the position
does not differ materially from that in the adult. It should also be noted that
the recto-vesical fold of peritoneum extends in infancy nearly as low as the base
of the prostate.
Vessels.-The arteries of the bladder are derived from the internal iliac and
internal pudic, and in the female some twigs are also given off by the uterine
arteries. The veins terminate in the internal iliac trunk. They form plexuses
which are especially large about the parts adjacent to the prostate, and communicate
in the male with the dorsal vein of the penis. Lymphatics are few, and are found
mostly in the neighbourhood of the internal meatus. They accompany the veins
and terminate in the pelvic glands.
Nerves. The nerves are derived, partly from the sympathetic system through
the hypogastric plexuses, partly from the cerebro-spinal system through the sacral
plexus. The former supply the mucosa, the latter the muscularis.


THE MALE REPRODUCTIVE ORGANS
The reproductive organs of the male consist of (1) two testicles or seminal
glands, with their excretory tubes; (2) a musculo-glandular organ, the prostate,
which provides a material for the dilution of the semen, and by its sphincteric
contraction aids in the ejaculation of the spermatic fluid, and at the same time
intercepts its retrograde passage into the bladder; (3) an organ of copulation,
the penis; and (4) a canal, the urethra, which pierces the prostate and penis, and
serves for the transit of both the generative and urinary secretions.
THE PROSTATE
The prostate is a firm elastic and contractile organ, lying between the bladder
and the penis, and perforated by the urethra (figs. 620, 624, and 649). It is
roughly comparable to a horse-chestnut in form and dimensions; its broader

THE PROSTATE
1059
extremity or base lies uppermost and blends with the vesical sphincter, while its
apex rests against the superior triangular ligament. Its long axis is vertical (in.
the erect posture), or inclines slightly forwards below (fig. 617), and is about an
inch and a quarter in length. Its transverse diameter, greatest near the base,
measures about an inch and a half, and its antero-posterior diameter about an
inch. Its average weight is about six drachms, nearly the same as that of the
testicle, and it may be noted that the active evolution of the two organs begins at
the same period, that of puberty, and that the structural and functional develop-
ment of the one is intimately associated with that of the other during the period
of sexual vigour. It offers for description a base, an apex, and anterior, lateral,
and posterior walls. The base is connected with the musculature of the bladder,
and usually lies a little above the level of the middle of the symphysis. The
apex, resting against the superior or deep triangular ligament, is about half an
inch behind and a little below the subpubic angle, and on rectal exploration will
FIG. 620.-SEMI-DIAGRAMMATIC SECTION OF THE MALE PELVIS.

MIDDLE LOBE OF PROSTATE ABOVE THE PROSTATIC FISSURE
SINUS POCULARIS IN PROSTATIC FISSURE
INTERNAL URINARY MEATUS
VASA DEFERENTIA AND VESICULA SEMINALES
ANTERIOR WALL OF RECTUM
MUCOUS MEMBRANE OF BLADDER
PERITONEUM
Fascia trans-
versalis
Recto-vesical
fascia
Fat in space
of Retzius
SYMPHYSIS
Vesico-pubic.
muscle
ANTERIOR WALL OF
PROSTATE WITH
CAPSULE
Dorsal vein
of penis
SEPTUM PECTINI-
FORME
CORPUS SPONGI-
OSUM URETHRA
CAVITY OF RECTUM WITH FOLD OF
KOHLRAUSCH
A
POSTERIOR WALL
OF PROSTATE
WITH CAPSULE
-Rectal por-
tion of recto-
vesical fascia
-Sphincter ani
LOWER END OF
RECTUM
Sphincter ani
Fascia of Colles
Deep transversus perinæi between superficial
and deep triangular ligaments
COWPER'S GLAND
Junction of deep and superficial triangular
ligaments with fascia of Colles
be found about an inch and a quarter above the margin of the anus. The anterior
wall is rounded, and is covered by the prostatic plexus of veins and the vesico-
pubic muscle and pubo-prostatic ligaments (page 1056). The lateral walls are in
contact with the inner borders of the two levatores ani muscles and the marginal
portion of the venous plexus, and project above in the form of ill-defined lobes,
the persistent indication of its development in two halves. The posterior wall is
flattened and is opposed to the rectum, from which it is separated by some con-
nective tissue and unstriped muscular fibres. Near its upper border is a transverse
median cleft, the prostatic fissure (fig. 624), which extends deeply inwards and
forwards towards the middle of the prostatic urethra, transmitting the common
ejaculatory ducts and the sinus pocularis, and in section (fig. 620) appearing to cut
off a portion of the substance of the organ, the so-called middle lobe,' from the rest.
An irregular artery, usually derived from the internal iliac trunk, is sometimes
found running by the side of the prostate to reach the dorsum of the penis, and may
be the source of dangerous hæmorrhage in lithotomy. It replaces one or more
of the terminal branches of the internal pudic.
3x2
1060
THE MALE REPRODUCTIVE ORGANS
Structure and function.-The prostate is invested by a fibrous capsule, derived
from the recto-vesical segment of the pelvic fascia. The organ itself is composed
of muscular and glandular tissue. The muscular element represents about three-
fourths of the entire mass, and consists principally of unstriped fibres, continuous
above with the vesical sphincter, and forming in the upper third of the organ a
ring of great firmness and strength, lying above the urethral orifices of the ejacu-
latory ducts, and discharging in all probability the function of intercepting the
backward flow of the semen and prostatic fluid into the bladder during sexual
congress; below this point the muscle is intermingled with gland tissue, and near
the apex with a quantity of striated fibres which are probably connected with the
deep transversus perinæi. Here it is still of considerable strength, and aids in the
forward propulsion of the mingled prostatic and seminal secretions; the ejaculation
being further aided by the deep transversus perinæi and bulbo-cavernosi.
The glands are of the branched tubular type, and lie chiefly in the posterior and
lateral parts of the organ, their ducts opening into the urethral recesses (prostatic
sinuses) by the sides of the verumontanum. They secrete a mucus, the principal
use of which is to dilute and give bulk to the semen, and they are sometimes the seat
of pathological concretions. In addition to the true glands are seen a number of
simple follicles in the anterior wall of the prostatic urethra, probably of the same
nature as the rest of the urethral follicles. The prostatic urethra will be described
hereafter (page 1074).
The organ is essentially generative, and serves also to reinforce the vesical
sphincter, but its absence in the female and its imperfect development in children
and eunuchs appear to entail no defect in the control of the bladder. The muscular
fibres are, however, to some extent represented in the female (page 1079).
Vessels and Nerves.-The arteries of the prostate arise from the adjacent
vesical and hæmorrhoidal vessels. The prostatic veins receive the dorsal vein of
the penis, and, after forming a plexus investing the anterior and a portion of the
lateral surfaces, terminate in the adjacent vesical veins. The lymphatics end in
the pelvic glands, and a small gland may sometimes be found on each side near the
base of the organ. The nerves are derived from the hypogastric plexus.

THE TESTICLES AND THEIR APPENDAGES AND COVERINGS

The two testicles lie in a common pouch of integument called the scrotum, and
each organ is invested in addition by a series of coverings which join in the middle
line to form a septum scroti. There are three principal layers: an outer (the dartos)
of unstriped muscular fibre, a middle (the cremasteric) containing striped muscular
fibre, and an inner serous (the tunica vaginalis), separated from each other by
layers of connective tissue. The coverings (fig. 621), named from without inwards,
are (1) the dartos; (2) the external spermatic fascia; (3) the cremasteric or middle
spermatic fascia; (4) the internal spermatic fascia; (5) subperitoneal fascia; and
(6) the tunica vaginalis.
THE SCROTUM.--The scrotal integument is more or less pigmented, and covered
in the adult by coarse scattered hairs. It presents in the middle line a longitudinal
ridge, the raphe, from which start on either side a multitude of transverse wrinkles.
Its sudoriparous and sebaceous glands are largely developed.
(1) The dartos is a thin reddish layer composed of elastic tissue freely inter-
mingled with unstriped muscular fibres. It is adherent to the deep surface of the
skin, but passes inward septally between the two testicles, forming a separate sac
for each, and is prolonged over the penis and perinæum. Its fibres for the most
part assume a direction at right angles to the scrotal wrinkles, of which they are
the cause. They are always moderately contracted in health, and contract still more

THE TESTICLES
1061
under the influence of cold and of mental emotion, but are not affected by electricity.
They become relaxed in conditions of general enfeeblement.
(2) The external spermatic or intercolumnar' fascia consists of a fatless,
laminated connective tissue, within and closely adherent to the dartos, blending
at the external inguinal opening with the strong fibrous bands crossing the columns
of the ring, and prolonged, like the dartos, over the penis and perinæum. It is
continuous behind with the deep layer of the superficial perinæal fascia, and above
with the superficial fascia over the symphysis.
(3) The cremasteric or middle spermatic fascia is a well-defined fibro-muscular
expansion covering the cord and testicle. It consists of a strong double lamina of
areolar and elastic tissue enclosing and connecting longitudinal bundles of striped
muscle, the fibres of which may be traced above to the external inguinal ring,
where they are divided into three principal sets: an inner, attached to the pubic
spine, an outer to that portion of the external oblique which forms the external
FIG. 621.-HORIZONTAL SECTION OF THE SCROTUM AND TESTICLE. (Diagrammatic.)


Skin
Dartos
External spermatic fascia
Septum scroti-
Cremasteric fascia
Parietal layer of tunica vaginalis
MEDIASTINUM TESTIS-
Internal spermatic fascia and
subperitoneal fascia
Cavity of tunica vaginalis
Visceral layer of tunica vaginalis
-Tunica albuginea
-Digital fossa
EPIDIDYMIS
VAS DEFERENS-
pillar of the ring, and an intermediate slip continuous with the lower border of the
internal oblique, and sometimes also with the transversalis. Below, the tunic
blends with the dartos opposite the lower extremity of the testicle. The cremaster
contracts during convulsive expiratory actions of the abdominal muscles and under
emotional influences.
(4) The internal spermatic or infundibuliform' fascia is a delicate connective
tissue derived from the fascia transversalis, and within this will be seen (5) a
laminated prolongation of the subperitoneal tissue closely investing the elements
of the cord above the limits of the tunica vaginalis.
(6) The tunica vaginalis is intimately connected with the testicle, and will be
described after that organ (page 1062).
Vessels and Nerves.-The skin and dartos are supplied by branches of the
external pudic and superficial perineal arteries, while the cremaster receives a
special branch from the deep epigastric; the corresponding veins communicate with
the pudic, the long saphenous, and the dorsal vein of the penis. The lymphatics
terminate in the innermost set of the inguinal glands (the lymphatics of the testicle
itself passing to the lumbar glands). The nerves are derived from the genito-
crural and superficial perinæal.
THE TESTICLES.-The testicles (fig. 622), two in number, are suspended from the
inguinal region by the spermatic cords. The left is supposed to hang somewhat
lower than the right in the majority of persons. Each gland consists of two


1062
THE MALE REPRODUCTIVE ORGANS
portions, the testicle proper and the epididymis. Its weight as a whole averages
between five and six drachms, rarely attaining the maximum of an ounce; it is about
an inch and a half in length, an inch and a quarter in depth (from the anterior to
the posterior border), and somewhat less than an inch in thickness. It is so sus-
pended in the scrotum that its upper extremity inclines a little more forward than
the lower, and its inner surface is turned slightly forwards as well as inwards.
The Testicle proper is shaped somewhat like a kidney bean; it is elongated from
above downwards, and flattened from side to side. Its surface is smooth and white,
and is covered by the visceral layer of the tunica vaginalis, except where it is in
contact with the epididymis.
FIG. 622.-THE LEFT TESTICLE WITH VESSELS AND DUCT. (After Sappey.)

Spermatic artery.
Spermatic veins.
VAS DEFERENS
with deferential artery
Branch of spermatic artery-
Vein
VAS DEFERENS
GLOBUS MAJOR OF EPIDIDYMIS-
HYDATID OF MORGAGNI-
BODY OF EPIDIDYMIS
Digital fossa
Vessels of epididymis
OUTER WALL OF BODY OF TESTIS-
GLOBUS MINOR
The Epididymis is adherent to the posterior and inferior part of the testicle proper
and inclines slightly to the outer side. It is enlarged above into a head or globus
major, and below into a tail or globus minor, the intermediate portion being called
the body.
The Tunica Vaginalis is a serous sac of peritoneal origin, which bears to the
testicle a relation similar to that of the serous pericardium to the heart. It consists
of parietal and visceral layers.
The visceral layer is intimately adherent to the testicle proper, and to the globus
major, and outer part of the body of the epididymis, and is prolonged upwards for
about half an inch upon the spermatic cord. On the outer side and above, it

THE TESTICLES
1063-
extends into a deep depression, the digital fossa, between the testicle and epididy-
mis; but it leaves uncovered nearly the whole of the globus minor and the internal
and posterior surfaces of the body of the epididymis, and it is in these situations.
that an important vascular communication is established between the gland and
its coverings.
The parietal layer, continuous with the visceral layer at the posterior and inferior
parts of the testicle and at the point of reflexion from the spermatic cord, becomes
loosely attached to the internal spermatic fascia by means of a prolongation of the
abdominal subperitoneal tissue. Under normal conditions the two layers are in
contact, the serous fluid being secreted only in sufficient quantity to moisten the
opposed surfaces. An undue increase of the amount constitutes the disease known
as vaginal hydrocele.
The testicle is occasionally so rotated upon its long axis that the epididymis
becomes turned towards the front of the scrotum. In this case, were a hydrocele
to occur, the sac would project posteriorly. The side to which a detached testicle
belongs may be distinguished by remembering that the epididymis is attached
behind, and that the digital fossa of the tunica vaginalis lies on the outer side.
In order to understand the relations of the organ to adjacent structures it is
necessary to learn something of the mechanism of its descent. The testicle is at
first an abdominal organ lying below the kidney and invested by a layer of peritoneum
(mesorchium) which is firmly adherent to its surface in front and at the sides. It
is moreover connected by bundles of unstriped muscular fibres, the gubernaculum
testis, with the pillars of the external inguinal ring and with the dartos at the
bottom of the scrotum. It begins to descend in the early part of the third month
of fœtal life, reaching the internal inguinal ring in the sixth month. It then passes
obliquely through the structures of the abdominal wall, preceded by a pouch of peri-
toneum and pushing before it, in succession, the subperitoneal tissue, an infundibuli-
form prolongation of the fascia transversalis, a few fibres of the internal oblique
(which form part of the cremaster), and the intercolumnar fascia, which braces
together the pillars of the external inguinal ring. At the eighth month it appears
at the external ring, and reaches the bottom of the scrotum shortly before birth.
The cause of this migration is still uncertain. The theory usually adopted is
that the descent is effected by the progressive shortening of the gubernaculum, and
in accordance with this view the unstriped muscular fibres connecting the bottom
of the gland with the scrotum are regarded as the remains of the central and
principal gubernacular band, while the lateral bands, ceasing to act after the testicle
has reached the external ring, are drawn down into the scrotum and appear as
scattered groups of fibres, the internal cremaster of Henle, lying amidst the
elements of the spermatic cord (fig. 626).
The peritoneal sac carried with the testicle is at first continuous with the
abdominal peritoneum. In most cases the tube of communication gradually
narrows, and at length, within a few days after birth, becomes entirely closed.
Sometimes, however, the process of obliteration is more or less incomplete.
Should it fail altogether, a portion of the abdominal viscera may pass into the
tunica vaginalis, and constitute the congenital variety of inguinal hernia; or
peritoneal fluid may accumulate in the testicular sac, and form a congenital
hydrocele. More frequently the continuity of the tunica vaginalis with the
peritoneum is interrupted; but a slender pouch of peritoneum, the processus
vaginalis, may run into the inguinal canal, and even through the external ring into
the cord, or the tunica vaginalis may be prolonged upwards upon the cord for a
considerable distance.
Should any portion of the abdominal contents enter the processus vaginalis,
it may pass through the inguinal canal as a hernia, and descend into the scrotum.
If at the same time the upward extension, of the tunica vaginalis be present, the

1064
THE MALE REPRODUCTIVE ORGANS
hernia with its sac may pass within it or invaginate it, and a surgeon called upon
to operate in such a case would probably open the tunica vaginalis before reaching
the peritoneal sac, and thus meet with three layers of serous membrane before
exposing the extruded intestine. A hernia of this kind is called' infantile.' Cystic
tumours may be formed by the distension of small unobliterated segments of the
funicular portion of the tube, and are called encysted hydroceles of the cord.
Structure (fig. 623). The testicle proper consists of a tubular parenchyma
enclosed within a strong fibrous tunic, the tunica albuginea.
The tunica albuginea (figs. 621, 623) is a dense white inelastic capsule of about
one-sixteenth of an inch in thickness in the greater part of its extent, but reaching
two or three times this admeasurement beneath the epididymis. It is perforated at
its upper and back part by the efferent seminal tubes which go to form the globus
major of the epididymis, and from its inner surface pass a number of sustentacular
processes, one of large size called the mediastinum testis or corpus Highmorianum,
and a multitude of others in the form of thread-like fibro-muscular filaments and
delicate septal planes of connective tissue, the trabecule. The mediastinum extends
forwards from the upper half of the posterior border, occupying about a fourth of
FIG. 623.-DIAGRAM OF THE TESTICULAR TUBULES.

COLLECTING TUBE
CONI VASCULOS!
-VASA EFFERENTIA
LOBULI
RETE TESTIS IN MEDIASTINUM TESTIS
TUNICA ALBUGINEA RECEIVING ATTACH-
MENT OF TRABECULE
TUBE OF EPIDIDYMIS
VAS RECTUM
-VAS ABERRANS
-VAS DEFERENS
the sagittal and a third of the transverse diameter of the interior, and is tunnelled
by blood-vessels and a network of seminal tubes (the rete testis). The trabeculæ
radiate from the deep aspect of the mediastinum to the inner surface of the
tunica albuginea and subdivide the interior of the capsule into a number of loculi
(150-200).
Within these loculi lie the testicular tubules, supported by a fine retiform
connective tissue which becomes condensed into a highly vascular lamina called
the tunica vasculosa where it is in contact with the albuginea. The proper
secreting substance consists of fine branching canals, the tubuli seminiferi, about
120th of an inch in diameter, and lined with a layer of cubical cells in which are
developed the spermatic filaments or spermatozoa. The tubules are collected into
little bundles, called lobules, about three hundred in number, each comprising two
or more separate tubes. These by their union form larger tubes, or tubuli recti,
which converge towards the mediastinum, and on entering it break up into a plexus,
the rete testis; from the rete in turn spring twelve to twenty efferent tubes, or vasa
efferentia, twice or three times as large as the tubules, and these, piercing the
upper and back part of the albuginea, end in the head of the epididymis (fig. 623).


THE TESTICLES
1065
9
The epididymis represents the second stage in the course of the seminiferous
vessels. The vasa efferentia, after their escape from the testicle proper, form each
a tube about six to eight inches in length, lined with ciliated epithelium and coiled
in such a manner as to assume the form of a conical mass, the conus vasculosus,
with the apex towards the albuginea. The coni vasculosi grouped together constitute
the globus major, and their respective tubules are collected by a single canal,
the tube of the epididymis, which by its complex coils, fifteen to twenty feet in
length, makes up the body and globus minor of the epididymis, and finally terminates
in the free portion of the duct, the vas deferens. It presents near its termination
one or more diverticula, the largest and most constant of which, the vas aberrans
of Haller, ranges from an inch and a half to fifteen inches in length, and runs up
between the body of the epididymis and the commencement of the vas deferens.
The tube of the epididymis, like those of the coni vasculosi, is lined with ciliated
epithelium, but its walls are thick, and contain two layers of unstriped muscular
fibres.
Two little bodies of some morphological interest are to be found appended to
the testicle proper and the globus major. The less constant of these, known as
the hydatid of Morgagni, is a pediculated sac from one-eighth to one-third of
an inch in length, dilated at its free extremity and containing a clear fluid; the
other, rarely absent, has about the same dimensions, but is usually sessile and
flattened, and may be subdivided into two or three lobes. It is believed to correspond
to the upper end of the Fallopian tube, and to be the remains of the Müllerian duct
(page 1094), the foetal structure from which are developed the most important part
of the internal genitals of the female.
Another relic, called the paradidymis, or organ of Giraldès, probably derived
from the Wolffian body (page 1094), is found over the lowest portion of the spermatic
cord immediately above the head of the epididymis. It consists of coiled tubules,
blind and dilated at both ends, lying beneath the visceral layer of the funicular
portion of the tunica vaginalis. It usually has the appearance of a white or
yellowish irregular patch about one-fifth of an inch in diameter. Any of these
embryonic structures may give rise to cystic tumours, and the aberrant tubes are
probably not an uncommon source of origin of true spermatic cysts containing
seminal fluid.
The testicle remains small until the period of puberty, when, together with the
prostate, it begins to undergo rapid development; but in some cases its evolution
is arrested before it has attained its full dimensions, and this is particularly liable
to occur when its descent into the scrotum has not taken place, or when a varicose
dilatation of its veins appears before adolescence. In old age it usually loses much
of its functional activity, but this is not invariably the case.
The VAS DEFERENS is the continuation of the tube of the epididymis, and extends
from the globus minor to the prostatic portion of the urethra. In the lower part
of its course it is slender and tortuous, but it becomes thicker and straighter as it
ascends along the back of the epididymis (testicular stage), and attains its full
size before it reaches the top of the organ. From this point it is the principal
element of the spermatic cord, and runs upwards almost vertically as far as the
external inguinal ring (funicular stage); entering the inguinal canal, it runs
obliquely outwards, upwards, and slightly backwards to the internal ring (inguinal
stage). It then quits the associated vessels of the cord, and, winding around the
origin of the deep epigastric artery to the inner side of the external iliac artery and
in front of the external iliac vein, enters the pelvis (pelvic stage) close to the ilio-
pubic suture, and runs downwards and backwards over the side of the bladder,
crossing it on the vesical side of the obliterated hypogastric artery and ureter, to
reach the side of the posterior wall of the viscus. Here it lies between the bladder
and the second stage of the rectum, and, becoming enlarged and sacculated, passes

1066
THE MALE REPRODUCTIVE ORGANS
downwards and inwards towards the base of the prostate, where it narrows and is
joined by the lower end of the vesicula seminalis. The common tube descends
as the ejaculatory duct to open into the prostatic portion of the urethra. The
two vasa deferentia, where they lie in front of the rectum, are separated by a
triangular interval, the apex of which is formed by the approximation of the
ejaculatory ducts, and lies immediately above the prostate. The whole of the pelvic
portion of the vas is subperitoneal except near its termination, where it is invested
only by recto-vesical fascia and an extension of subperitoneal tissue. The entire
length of the vas deferens averages about twenty-four inches, of which an inch
and a half may be allotted to the testicular stage, three inches to the funicular
stage, an inch and three-quarters to the inguinal stage, and the rest to the pelvic
stage. It is cylindrical and of uniform diameter (about one-tenth of an inch) in.
its funicular, inguinal, and pelvic stages down to the retrovesical portion, and

FIG. 624.-VASA DEFERENTIA AND VESICULE SEMINALES. (After Sappey.)

EJACULATORY DUCT.
SINUS POCULARIS-
VERUMONTANUM-
ORIFICE OF EJACULATORY-
DUCT
AMPULLA OF VAS DEFERENS.
UNION OF VESICULA.
WITH VAS
EJACULATORY DUCT ENTERING-
PROSTATIC FISSURE
PROSTATE-
MEMBRANOUS URETHRA-
VAS DEFERENS
ORIFICE OF SINUS
POCULARIS
LOWER END OF
VERUMONTANUM
VESICULA SEMINALIS
its walls are of great thickness, about one-twenty-fifth of an inch, while its calibre is
extremely small. It is here composed of an outer cellular coat containing vessels
and smooth muscular fibres, a threefold muscular coat with external and internal
transverse and middle circular layers, and a mucous membrane lined with cylindrical
epithelium. The ampullated retrovesical portion differs from the rest in the thin-
ness of its walls and in its sacculation (fig. 625).
The VESICULE SEMINALES are two diverticular reservoirs situated between the
bladder and rectum external to the ampullæ of the vasa deferentia.
Each vesicula is of somewhat triangular form, its broad upper extremity lying
beneath the peritoneum, its apex joining the vas deferens at the base of the
prostate. It averages about two and a quarter inches in length and half an
inch in diameter at its base. It is lobulated on the surface, and on dissection
is found to consist of a central tube from three to five inches in length, with

VESICULA SEMINALIS
1067
two or more short lateral branches. It is related in front to the posterior wall
of the bladder, and by its upper extremity overlaps the ureter; posteriorly it is
covered by the recto-vesical pouch of peritoneum, for a short distance above; and
below this point it lies in direct contact with the front of the rectum, and external
to the ampulla of the vas deferens. It becomes constricted at its junction with
the vas. Structurally it consists of a fibrous external coat; a middle muscular
coat in two layers, external longitudinal and internal transverse; and an internal
mucous membrane, plicated, yellowish brown in colour, and lined with cylindrical
epithelium. It is invested, together with the ampulla of the vas, by a kind of
sheath of fibrous tissue and by a layer of smooth muscular fibres which is pro-
bably accessory in function to the contractile element of the proper wall of the
tubes.
FIG. 625.-VAS DEFERENS AND VESICULA SEMINALIS DISSECTED. (After Sappey.)

DIVERTICULA
DIVERTICULA
{
SACCULI OF AMPULLA OF VAS
SACCULUS
JUNCTION OF VAS AND VESICULA
EJACULATORY DUCT
The EJACULATORY DUCT, formed on each side by the union of the vas deferens
and vesicula seminalis, is an infundibuliform tube about three-quarters of an inch
in length, and about an eighth of an inch in width above, narrowing to one-third
of that size below, while the lumen near its opening is not more than one-fiftieth of
an inch in diameter. The two ducts converge slightly as they descend, and finally,
passing behind the so-called 'middle lobe,' the hinder part of the basal muscular
ring of the prostate (page 1060), pierce the prostatic fissure and open on to the
verumontanum on either side of the orifice of the sinus pocularis (fig. 624).
Vessels and Nerves of the testicle and its appendages. The testicle is supplied
with blood by the spermatic and deferential arteries, the two vessels anastomosing
with each other and with the scrotal arteries at the lower extremity of the gland.
The corresponding veins, spermatic and deferential, form like communications and
run up in two separate groups. The spermatic veins, large and imperfectly valved,
1068
THE MALE REPRODUCTIVE ORGANS
spring from the upper part of the testicle, and, running in front of the deferential
veins around the spermatic artery, are connected to each other by means of short
transverse branches; finally, the right ends in the vena cava, the left in the left
renal vein. The lymphatics of the vas and testicle accompany the veins. The
former terminate in the pelvic iliac glands, the latter in the lumbar glands.
The free anastomosis between the deferential, spermatic, and scrotal blood-
vessels explains why the ligature or excision of the spermatic veins and artery in
varicocele leaves the nutrition of the testicle unimpaired; while the intercom-
munication of the testicular and scrotal blood and lymph vessels behind the
epididymis accounts for the extension of inflammatory affections of the epididymis
to the scrotal integument.
The Nerves of the testicle come from the aortic, renal, and hypogastric plexuses.
The vesicula seminalis is supplied by the deferential, inferior vesical, and
middle hæmorrhoidal arteries: its lymphatics end in the pelvic glands, and the
nerves are derived from the hypogastric plexus.
SPERMATIC CORD
The spermatic cord is the elongated pedicle of the testicle. It extends
from the internal inguinal ring, where its component structures are collected
together, through the inguinal canal, and into the scrotum as far as the summit of
the testicle. Its constituent elements are as follow (fig. 626).
FIG. 626.-SECTION OF THE SPERMATIC CORD. (After Henle.)

Vein-
Fat-
Small artery-
Artery of vas-
Internal cremaster-
Vein
-Fat
Vein
VAS DEFERENS:-
Mucous membrane
-Internal muscular coat
C
NERVE-
NERVE-
Middle muscular coat
External muscular coat
Small artery-
-Internal cremaster

1. The vas deferens, lying with the deferential vessels posterior to the other
structures, and recognisable by its cord-like resistance to pressure.
2. The spermatic artery.
3. The spermatic veins, or pampiniform plexus, surrounding the artery.
4. Lymphatics running with the veins.
5. Sympathetic nerves accompanying the artery.
6. The processus vaginalis, a thread-like relic of the tube of communication

ALDO THE PENIS
1069
between the tunica vaginalis and peritoneum. It is frequently patent for a short
distance near the internal inguinal ring, and probably accounts in great part for the
insidious development of hernial protrusions in this region.
7. The internal cremaster of Henle. Scattered bundles of smooth muscular
fibres, said to represent the inverted lateral bands of the gubernaculum testis.
8. Fat and connective tissue, continuous above with the subperitoneal planes
of fascia.
In the scrotum these various structures are invested by coverings identical with
those of the testicle.
THE PENIS
The penis is composed of three rod-like segments of erectile tissue, firmly
united together and invested by a sheath composed of integument, dartos, and
fascia (fig. 627).
Of these three erectile segments, two, the corpora cavernosa, are placed side by
side above or dorsally; the third, the corpus spongiosum, is perforated in the whole
length by the urethral canal, and lies on the ventral aspect of the former, except
where it expands distally to form the free end of the organ (fig. 628).
The penis as a whole may be divided into a root, a body, and a terminal
enlargement or glans; the root is attached to the symphysis and pubic arch; the
body, prismatic in section with rounded angles, forms the greater part of the
free portion of the organ; and the glans is a heart-shaped expansion, more
developed on its dorsal than on its ventral aspect, and presenting the urethral

FIG. 627.-TRANSVERSE SECTION THROUGH THE BODY OF THE PENIS.
Integuments of penis
External layer of tunica
albuginea
Internal layer-
Erectile tissue-
Erectile tissue of corpus
spongiosum
URETHRA
Dorsal vein

Dorsal artery
DORSAL NERVE
orifice at its distal extremity. The body and glans are separated by a constriction
called the neck.
The coverings of the penis are continuous with those of the testicle. The skin,
like that of the scrotum, is pigmented, fatless, and highly elastic. It contains large
sebaceous glands, which in the neighbourhood of the neck of the organ secrete a
whitish fatty odorous substance, the smegma præputii. It moves freely upon the
subjacent parts except over the glans, where it is firmly adherent. At the neck it
becomes peculiarly redundant, and forms a fold, the prepuce, which more or less
completely conceals the glans. The deeper layer of the duplicature, which is turned
towards and is continuous with the skin of the glans, is sometimes erroneously
termed 'mucous membrane.' A small median plication, the frænum præputii,
extends from the prepuce to the lower surface of the glans. This contains vessels of
some size, and, if ruptured, may give rise to considerable loss of blood.
1070
THE MALE REPRODUCTIVE ORGANS
The dartos is continuous with the dartos tissue (page 1060) of the scrotum, and
consists of smooth muscle, the fibres of which are for the most part disposed
longitudinally. It enters into the formation of the prepuce, and according to Sappey
forms a kind of sphincter around the preputial orifice. Beneath the dartos is a
loose connective tissue very liable to infiltration in inflammatory or dropsical con-
ditions and in urinary extravasation. Within this lies the fascial sheath of the
penis, a complete and highly elastic tunic investing the entire organ as far as the
base of the glans, where it fuses with the integument. The suspensory ligament
of the penis is a strong band of fibrous tissue which passes from the front of the
symphysis to the subjacent portion of the organ, blending with the fascial sheath
in the middle line and at the sides. The angle of the penis corresponds to the
most anterior point of suspension to the symphysis.
The corpora cavernosa constitute the dorsal and larger part of the penis. They
are closely united in the greater part of their extent, but separate for a short distance
in front and diverge somewhat widely behind. The posterior extremity of each,
called the crus penis, at first enlarges slightly, but tapers as it approaches the
subpubic arch; then, becoming tendinous and somewhat flattened, is strongly
attached to the ischio-pubic rami; and the distal end, pointed somewhat like the
tip of a cigar, is plunged into the substance of the glans (fig. 628). The entire
length of the corpus cavernosum averages about six inches, and its breadth about

FIG. 628.-TRANSVERSE SECTION OF THE PENIS THROUGH THE BASE OF THE GLANS.

CORPUS SPONGIOSUM (GLANS)
DISTAL EXTREMITY OF CORPUS
CAVERNOSUM
URETHRA
CORPUS SPONGIOSUM Integument
half an inch, but it increases in size by one-third or more when its vascular spaces
are fully distended.
In structure it consists of a sponge-like erectile tissue invested by a strong
sheath or tunica albuginea. The sheath is about a line in thickness, white,
remarkably tough, and consists of two laminæ, an external, of longitudinal fibres
common to both corpora cavernosa; and an internal, of circular fibres surrounding
each corpus and forming a mesial septum pectiniforme where the two corpora
cavernosa come into contact. The framework of the cavernous structure is formed
by a reticular arrangement of fibro-muscular trabecular bands, starting from the
inner surface of the albuginea and becoming more slender as they approach the
axis of the body. The branches of the supplying artery run in the trabeculæ and
terminate by opening into the anastomosing intertrabecular spaces which represent
the widely dilated capillaries of the organ.
The corpus spongiosum lies in the middle line and below the united corpora
Unlike the latter it has no direct attachment to the pelvic bones, but
terminates at each end in a bulbous expansion. It may be divided into a glans,
a body, and a bulb.
The anterior enlargement, or glans, is somewhat heart-shaped, its base extending
much farther over the dorsal than over the ventral aspect of the corpora caver-

THE PENIS
1071
nosa, and showing a distinct indication of division into two lateral lobes in the
latter situation. The most prominent part of the base is called the corona glandis,
and the furrow behind this is the neck of the penis. At its tip it presents a
vertical fissure about one-third of an inch in length, the external urinary meatus
or outlet of the urethra.
The glans is composed of erectile tissue with coarse trabeculæ, and is covered
with a firmly adherent layer of skin continuous with the inner layer of the prepuce.
Its capacity for vascular engorgement is much less than that of the corpus spongi-
osum, and it never attains a like degree of hardness during erection.
The body of the corpus spongiosum is cylindrical, uniform in diameter, and
FIG. 629.-THE MALE PERINEUM. (Modified from Hirschfeld and Leveillé.)
BULBO-CAVERNOSUS
Superficial triangular ligament
ISCHIO-CAVERNOSUS
Muscles of thigh
INFERIOR PUDENDAL NERVE
SUPERFICIAL PERINEAL NERVE
INFERIOR HÆMORRHOIDAL NERVE
CUTANEOUS BRANCH OF FOURTH SACRALI
Sphincter ani
Gluteus maximus
TUBEROSITY OF ISCHIUM
Great sacro-sciatic ligament
Levator ani
Superficial transversus perinæi
traversed axially in its whole length by the urethra; it is lodged above in a groove
between the two corpora cavernosa, while its ventral aspect is subcutaneous except
where it corresponds to the attachment of the scrotum. Structurally it is provided
with a thin albuginea, between which and the urethra lies a narrow layer of erectile
tissue.
The bulb is formed by an expansion of the erectile structure, and the portion of
the urethra by which it is traversed undergoes a well-marked dilatation, and lies
nearer its upper than its lower surface. It is about an inch and a half in length,
and its greatest width is about three-quarters of an inch. It is surrounded by the
bulbo-cavernosi muscles, the greater part of the fibres of which pass between it'
1072
THE MALE REPRODUCTIVE ORGANS
and the corpora cavernosa to blend together in the middle line; and it rests
posteriorly against the superficial triangular ligament about half an inch in front.
of the anus. It is liable to considerable enlargement after middle age.
Muscles. The muscles of the penis are three on each side-the ischio-
cavernosus, the bulbo-cavernosus, and the superficial transversus perinæi (fig. 629).
The ischio-cavernosus (erector penis) arises from the inner surface of the
tuberosity and ramus of the ischium, from the pubic ramus, and from the adjacent
root of the crus penis, and is inserted into the surface of the tunica albuginea of
the corpus cavernosum near the point of attachment of the suspensory ligament.
A slip, the compressor venæ dorsalis, is occasionally detached from its more distal
portion, and becomes inserted into the fascial sheath of the penis over the dorsal
vessels, or may blend with its fellow in a narrow tendon in this situation.
The bulbo-cavernosus (accelerator urinæ) arises from a median raphe which
extends from the anterior extremity of the sphincter ani along the whole length
of the bulb as far as the level of the symphysis. A few of its more posterior fibres
pass outwards to become inserted into the superficial triangular ligament and into
the bulb, and a bundle of its most anterior fibres may, like the similar slip from
the ischio-cavernosus, form a sling around the corpora cavernosa and become
attached to the fascial sheath of the penis, or it may be inserted into the side of the
corpus cavernosum itself. In the former case it acts as a compressor of the dorsal
vein. The rest of the fibres pass around the bulb to become lost in the connective
tissue on the dorsal aspect of the latter, between it and the corpora cavernosa; the
two muscles thus practically encircle the bulb, and act as an annular sphincter upon
the contained portion of the urethra. It is often joined by fibres from the sphincter
ani and deep transversus perinæi.
The superficial transversus perinæi is the most variable of all the perinæal
muscles. It usually arises from the inner surface of the tuberosity and ramus of
the ischium, blending with the origin of the ischio-cavernosus, and passes inwards.
and forwards to its insertion into the tendinous centre of the perinæum, interlacing
with the posterior fibres of origin of the bulbo-cavernosus. Some of its fibres may
blend with those of the sphincter ani and levator ani.
These three pairs of muscles possess each a thin fascial sheath, and lie in the
superficial perinæal interspace between the fascia of Colles and the superficial
triangular ligament. They are supplied by branches of the deep division of the
superficial perinæal nerves and vessels.
The action of the penile muscles is not very obvious. The compressores venæ
dorsalis when present may aid in erection by impeding the return of venous blood
from the organ, but there is no reason to believe that any disadvantage attaches.
to their absence. The bulbo-cavernosus, with its fellow, is however of value as a
compressor of the bulbous portion of the urethra, and thus assists in the ejaculation
of the semen, continuing the action of the ejaculatory fibres of the prostate and of
the deep transversus perinæi; and it may also be of service in expelling the last
drops of the urine. The compression of the vessels of the bulb favours the engorge-
ment of the rest of the corpus spongiosum.
The ischio-cavernosus in the absence of its dorsal fasciculus can scarcely justify
its older name of erector penis, but it appears to have the power of impressing
voluntary movements upon the turgid organ. The superficial transversus perinæi
is accessory to the bulbo-cavernosus, fixing the raphe from which its fibres arise,
and it adds slightly to the strength of the muscular floor of the pelvis.



THE URETHRA
1073
THE URETHRA

The urethra is the mucous canal extending from the bladder to the extremity of
the glans penis. In its course it pierces the prostate from base to apex, the deep
and superficial triangular ligaments with the intervening compressor urethræ, and
the whole length of the corpus spongiosum. It may hence be divided into three
segments:-(1) Prostatic; (2) membranous (the portion lying in the space between
the two transverse ligaments); and (3) spongy (fig. 630).
FIG. 630.-THE MALE URETHRA, CLEFT DORSALLY TO SHOW VENTRAL MUCOUS WALL.

URETER
Plica uretica
SECTION OF BLADDER
INTERNAL URINARY MEATUS
PROSTATIC SINUS WITH OPENING
OF PROSTATIC GLANDS
SINUS POCULARIS
FOLLICULAR GLANDS OF DORSAL WALL
-SECTION OF PROSTATE
-VERUMONTANUM
-EJACULATORY DUCT
-PROSTATIC GLANDS
COWPER'S GLAND
SEPTUM PECTINIFORME
MEMBRANOUS URETHRA
SECTION OF CORPUS CAVERNOSUM
THIN LAYER OF CORPUS SPONGIOSUM
ORIFICE OF COWPER'S GLAND
BULBOUS PORTION OF URETHRA
Albuginea of corpora cavernosa
Mucous membrane
FOSSA NAVICULARIS
-PREPUCE
-GLANS PENIS
EXTERNAL URINARY MEATUS
3Z
1074
THE MALE REPRODUCTIVE ORGANS
Its average length is still variously stated by different authorities, but the inves-
tigations of Cazenave and Sappey, confirmed as they are by the frozen sections of
Braune and others, set the matter at rest so far as the physiological condition is
concerned. In the ordinary relaxed state of the penis the distance between the
internal and external meatus does not usually exceed six inches and a half, and
may be less than this when the gan is contracted to its minimum degree. But
under the test of catheterism the length of the canal is undoubtedly greater, and
may reach seven or eight inces or even more, owing to the traction upon the
penis which accompanies the operation. The canal may be greatly lengthened
also by senile hypertrophy of the prostate, which carries the internal meatus upwards
towards the level of the top of the symphysis.
The diameters of the passage are scarcely capable of accurate measurement.
In the ordinary condition it is represented by a fissure, and its limits of safe
dilatability can only be approximately calculated. Otis's investigations show
that these limits are wider than was formerly believed to be the case, and he
has endeavoured to establish as a law that there is a ratio between the maximum
circumference of the canal and that of the penis, of four to nine. Thus a penis
having in its ordinary state a circumference of thirty-six lines should possess
a urethra capable of admitting an instrument of sixteen lines. The sources of
fallacy in such an observation are not inconsiderable, but they do not destroy its
value as a practical guide to the surgeon.
The prostatic portion is about an inch and a quarter in length, wider in
the middle than at the two extremities, and perpendicular in direction, or slightly
inclined downwards and forwards. Its anterior wall is concave both in longitudinal
and transverse sections, and is studded with the orifices of small mucous follicles;
the posterior wall presents a longitudinal ridge called the colliculus seminalis or
verumontanum, highest near the middle and gradually diminishing above and
below. A little above the centre of the colliculus may be seen a rather large
opening which leads to a cul-de-sac of especial interest for the morphologist, the
sinus pocularis or uterus masculinus, and on the lateral margins of the orifice
of the sinus are seen two small puncta, one on each side, the openings of the
ejaculatory ducts. The sinus pocularis and ducts may be traced upwards and
backwards through the prostatic cleft and behind the sphincteric fibres which
constitute the prostatic bar or middle lobe of the prostate.
In consequence of the presence of the colliculus the urethral fissure appears on
horizontal section as a U-shaped curve with forward convexity. The recesses
corresponding to the extremities of the U are sometimes called the prostatic sinuses,
and into these open the orifices of the posterior and lateral prostatic glands.
The mucous membrane of the prostatic urethra is lined with a laminated epi-
thelium. Beneath this is a layer of erectile tissue which constitutes the principal
element of the colliculus, and is in turn supported by a layer of longitudinal muscle.
The sinus pocularis is believed to be the homologue of the uterus. It is about
half an inch in length, and terminates by a blind slightly dilated extremity. Its
walls consist of connective tissue intermingled with smooth muscular fibres, and
covered with laminated epithelium. It contains a few simple or compound glands,
in which small concretions are occasionally found.
The membranous portion, bounded above and below by the superior and
inferior triangular ligaments, is from half to three-quarters of an inch in length;
it is inclined downwards and somewhat forwards, and lies about an inch behind the
subpubic ligament, from which it is separated by the muscular fibres of the deep
transversus perinæi and a plexus of veins. The posterior wall is shorter than the
anterior, owing to the convergence of the two triangular ligaments as they pass
backwards to unite with the posterior border of the fascia of Colles. It is closely
related on either side to Cowper's glands.



THE VULVA
1077
The structures forming the labia resemble those of the scrotum, but the dartos
is imperfectly developed, and each labium contains a well-defined encapsulated
subcutaneous mass of fat, of somewhat ovoid shape, which blends above with the
distal extremity of the round ligament. A similar mass is occasionally found in the
male scrotum as a fatty tumour of the cord, and may simulate an inguinal hernia.
The labia minora, or nymphæ, are folds differing from the labia majora in their
relatively small size and in the absence of fat. The two plications unite above,
embracing the clitoris and forming the præputium clitoridis; below, they diverge
and terminate opposite to or a little behind the middle of the rima genitalis. They
are smooth and hairless on the surface, usually of a pale rose colour, and their free
border, which projects for a very variable distance, is convex and often crenulated
or lobed. They are usually concealed by the labia majora, except in the foetus;
but are sometimes largely developed, and may project beyond the genital fissure,
FIG. 632.-DIAGRAMMATIC REPRESENTATION OF THE PERINEAL STRUCTURES
ISCHIO-PUBIC ARCH-
CRUS CLITORIDIS WITH-
ISCHIO-CAVERNOSUS
BULBO-CAVERNOSUS-
COVERING BULBUS
VESTIBULI
Superficial trian-
gular ligament
IN THE FEMALE.

GLANS CLITORIDIS
WITH PREPUCE
PARS
INTERMEDIALIS
Mucous mem-
brane of
vestibule
MEATUS URINARIUS
BULBUS VESTIBULI
ACE
GLAND OF
BARTHOLIN
Sphincter ani
then assuming a dry pigmented aspect. The sebaceous glands are large and occupy
both surfaces.
The vestibule is the space between the labia minora and the vaginal orifice.
Its boundaries are ill defined posteriorly, and the term is used with different signi-
ficance by different anatomists. Opening into it are the urethra, the glands of
Bartholin, and the orifices of a number of lacunæ.
The glands of Bartholin probably represent Cowper's glands in the male,
but are more superficially placed. They are two little racemose glands, about a
third of an inch long, situated one on either side beneath the lateral wall of the
vestibule and behind the bulbi vestibuli. The duct, about three-quarters of an
inch in length, opens immediately in front of the vaginal orifice opposite its meridian.
Vessels. The vulvar structures are supplied by branches of the external and
internal pudic arteries. The veins end in the corresponding trunks, and there is
in addition a free anastomosis with the veins of the round ligament in the
subcutaneous fat of the labium. The lymphatics terminate for the most part
in the inguinal glands, a few passing to the femoral glands. About the vaginal
1078
THE FEMALE REPRODUCTIVE ORGANS
orifice is a neutral territory in which the vulvar and vaginal absorbents inter-
communicate.
The erectile structures of the vulva correspond morphologically to those of the
male organ; the corpora cavernosa are represented by the clitoris, and the corpus
spongiosum, cleft in the female by the vulvar orifice, appears beneath the mucous
membrane of the vestibule in the form of two vascular plexuses, one on each side,
called the bulbi vestibuli (fig. 632).
FIG. 633.-SECTION OF THE FEMALE PELVIS. (After Henle.)

UTERUS
SYMPHYSIS
PERITONEUM
VESICAL WALL
CAVITY OF
BLADDER
PREVESICAL FAT
Dorsal vein
CLITORIS
Deep trans-
versus perinæi
RECTUM
COCCYX
Recto-coccy-
geal muscle
POSTERIOR LIP
OF OS UTERI
ANTERIOR LIP
VAGINA
External
sphincter ani
Internal
sphincter ani
LABIUM MAJUS
Unstriped muscular fibre
URETHRA
LABIUM MINUS
ANUS
Internal sphincter ani
Part of external sphincter ani
Unstriped muscular fibre
Vessels
VAGINAL ORIFICE
The CLITORIS appears as a diminutive penile appendage at the upper part of
the vulva, and is embraced by a kind of prepuce formed by the union of the two
labia minora. It is composed of two corpora cavernosa which differ from the
corresponding masculine structures only in their size and in their union distally
into a rounded imperforate extremity, the glans clitoridis. The crura are supported
dorsally by a suspensory ligament, and are attached to the ischial rami in the same
manner as in the male.
The clitoris is relatively smaller in the adult than in the child, and is almost
always concealed within the rima pudendi. It is a highly sensitive organ, and is
capable of erection.
The bulbi vestibuli are two erectile bodies of somewhat pyriform shape, lying
one on either side of the vestibule beneath the mucous membrane. The larger

THE CLITORIS
1079
extremity of each is posterior and extends backwards nearly to the posterior
commissure, touching the gland of Bartholin. The narrow anterior extremity, the
pars intermedialis of Köbelt, runs forwards to meet its fellow of the opposite side
beneath the clitoris. Superiorly, it is fixed to the superficial triangular ligament
of the perinæum, while it is in relation internally to the urethral and vaginal
orifices, and externally is invested by the fibres of the bulbo-cavernosus. It
consists of erectile tissue, enveloped by a thin tunica albuginea. During the
condition of engorgement it helps to narrow the vestibular portion of the vulva and
the entrance of the vagina.
The vessels and nerves of the clitoris and bulbi vestibuli are the same as those
of the analogous parts of the male.
The muscles appended to the erectile structures again are very similar to those
described in connection with the penis. The ischio-cavernosi are identical in
attachments with the erectores penis; but the bulbo-cavernosi are separated in
the middle line by the vulvar fissure, and appear on each side as a delicate, and
sometimes very indistinct, plane of muscular fibres, called the constrictor vaginæ,
attached behind to the tendinous centre of the perinæum, and breaking up in front
into tendinous slips which run in close external relation to the bulbi vestibuli,
and become lost above and below the clitoris. Their function is to compress the
bulbs and to constrict the vestibule and vaginal orifice. The transversi perinæi
have the same connections as in the male.
THE URETHRA (fig. 633).-The female urethra represents only the upper part of
the male canal. It is similarly related to the superior and inferior triangular liga-
ments, but is deficient in the sphincteric and glandular structures supplied to the
male urethra by the prostate. It is about an inch and a quarter in length, and is
directed upwards and slightly backwards to open into the bladder about three-
quarters of an inch behind the middle of the symphysis. Its posterior wall is in con-
tact with the vagina, and it is surrounded in front and at the sides by a plexus of
veins (plexus of Santorini). The posterior margin of the meatus usually presents
a tubercular prominence by which the position of the orifice may be distinguished
during catheterism.
As in the male urethra, the narrowest portion of the canal is the external meatus,
but the whole tube is sufficiently dilatable in most cases to allow the careful intro-
duction of the finger while the patient is under an anesthetic. A case is recorded
by William Cowper (1697) in which, as a result of an imperforate condition of the
hymen, it became the channel of sexual congress.
In structure it consists of a mucous membrane presenting a few lacunæ and
some rudimentary glandular follicles, and a muscular coat divisible into external
circular and internal longitudinal layers, both intermingled with fibres of elastic
tissue and with large venous plexuses which may undergo varicose dilatation near
the external orifice and form a pile-like tumour. It is surrounded by a muscular
sphincter composed of striped and unstriped fibre corresponding to the deep
transversus perinæi in the male, and partly perhaps to the musculature of the
prostate.

THE VAGINA
The vagina is a passage which extends upwards from its external opening at
the vestibule, and terminates above by embracing the neck of the uterus. Its vulvar
aperture is guarded in the virgin by a fold of mucous membrane called the hymen.
Form and direction (figs. 633, 634).-In its ordinary condition the vaginal
canal is represented by a fissure which in horizontal section assumes the form
of the letter H, with a transverse limb about an inch in length and two short
vertical limbs (fig. 633). In longitudinal section (fig. 633) the fissure branches above,
1080
THE FEMALE REPRODUCTIVE ORGANS
a short limb (occasionally ill-marked or absent) passing in front of the anterior
lip of the os uteri, a much longer limb extending behind the os to end about three-
quarters of an inch above the extremity of the posterior lip. The angle of reflexion
of the vaginal on to the uterine mucous membrane is called the fornix. The
direction of the passage is upwards and slightly backwards, forming an angle of
10° to 15° with the long axis of the body, and usually presenting a slight posterior
concavity adapted to the convexity of the rectal ampulla; the course and direction,
however, vary with the degree of pelvic inclination peculiar to the individual, and
to some extent with the condition of the bladder and rectum.
The two walls are of very unequal length, the anterior measuring about two
inches and a half, while the posterior is prolonged upwards an inch further.
Relations. Anteriorly, it is opposed to the urethra and posterior wall of the
bladder. It is intimately united with the lower two-thirds of the urethra, but is
separated from the upper third and from the bladder by loose connective tissue
continuous with the subperitoneal fascia. The ureters pierce the vesical wall in
FIG. 634.-HORIZONTAL SECTION OF VAGINA AND ADJACENT STRUCTURES. (After Henle.)

URETHRA
VAGINA-
Levator ani
RECTUM.
front of the vagina an inch and a quarter below the level of the os uteri. Posteriorly,
it is in relation with the rectum, but is separated from it above for about an inch
by the peritoneal cul-de-sac called the pouch of Douglas, in the middle by sub-
peritoneal connective tissue, and below by the tissues of the perineal body. In the
latter situation the two canals diverge, and the perinæal body hence appears on
sagittal section as a triangle the base of which is formed by the integument.
Laterally, it is in contact with the vaginal branch of the uterine artery, and a
venous plexus lying in the subperitoneal tissue at the base of the broad ligaments.
It is crossed obliquely in its upper third by the ureters, and in its lower two-thirds
by the anterior borders of the levatores ani. The finger passed within the passage
and pressed to either side may be made to feel the resistance of the pelvic wall, and
to distinguish the presence or absence of morbid growths or effusions. The duct
of Gartner, a relic of the Wolffian duct, may occasionally be found by the side of
the upper half of the vagina as a minute tube or fibrous cord. Two orifices which



THE VAGINA
1081
open into the vagina near the meatus, sometimes called Skene's tubes, are regarded
by some morphologists as the terminations of Gartner's ducts.
The lower end of the vagina pierces the triangular ligament, and it is here that
the resistance to dilatation is greatest. The inlet may be temporarily narrowed by
the engorgement of the bulbi vestibuli, or by the action of the constrictor vaginæ,
and perhaps also by that of the levatores ani.
The mucous surface of the vagina presents on the anterior wall a median
longitudinal ridge or carina, and on the posterior wall two ridges, the columnæ
rugarum, from all of which pass a number of transverse rugæ. These markings
diminish in distinctness with advance in age and with successive parturitions.
The hymen has been a subject of much speculation amongst the learned and
unlearned of all ages. Its very existence was at one time denied by many great
authorities, and the significance to be attached to its presence or absence is still
a question in medical jurisprudence. It appears in the virgin as an imperfect
septum pierced by an irregular aperture which usually reaches to the anterior
vaginal wall, and leaves a fold of semilunar form behind. It varies greatly in
strength and elasticity, and although it is nearly always ruptured by the first act of
sexual congress, it may remain unbroken until parturition. An imperforate con-
dition of the membrane is occasionally present, and may necessitate a surgical
operation at the commencement of the menstrual period.
Structure. The vaginal wall is composed of three coats, fibrous, muscular, and
mucous, and has a thickness of one-eighth to one-sixth of an inch. The outer
fibrous coat is derived from the recto-vesical fascia, and holds in its meshes a
plexus of veins. The muscular coat comprises two layers of strong unstriped
fibres, the outer longitudinal, continuous above with the uterine muscle and with
the utero-sacral ligaments; and the inner circular and more largely developed near
the vulvar aperture.
The mucous membrane presents the plications described, and is of a pale rose
tint in periods of quiescence, but becomes turgid during the catamenial period and
in pregnancy. It is highly elastic, beset with papillæ and covered with a squamous
laminated epithelium continuous with that of the os uteri and vulva.
Vessels and Nerves.-The arteries are derived from an inferior branch of the
uterine and from the internal iliac, communicating below with branches of the
external pudic; they run along the lateral aspect of the passage and give twigs to
the anterior and posterior surfaces. The veins, similarly disposed, form a rich
network in the muscular and mucous coats, and terminate in the vaginal and uterine
trunks. The lymphatics accompany the veins and terminate in the pelvic glands,
a few from the neighbourhood of the vestibule, however, reaching the inguinal
glands. A small gland is occasionally found between the rectum and vagina.
The Nerves come from the hypogastric plexus, the fourth sacral, and the pudic.


THE UTERUS
The uterus, or womb (figs. 635-638), is a hollow muscular organ lined with
mucous membrane. It communicates above with the two Fallopian tubes, and below
with the vagina, and lies within the pelvic cavity between the bladder and rectum,
fixed in its place by folds of peritoneum and certain bands of unstriped muscle.
It varies greatly in size and form at different periods of life and under different
physiological conditions.
The adult uterus is flattened from before backwards, pyriform in its outlines
when seen from the front, and is divided into two main portions, body and cervix,
by a transverse constriction, the isthmus. The isthmus may be regarded as the
weak point in the organ, and it is here that the various pathological flexions take
1082
THE FEMALE REPRODUCTIVE ORGANS
place. Its position in the virgin uterus is about midway between the two extremi-
ties, but it lies near the junction of the middle and lower thirds in women who have
FIG. 635.--THE FEMALE ORGANS OF GENERATION. (Modified from Sappey.)
(Vagina divided and laid open behind.)
POSTERIOR SURFACE OF BODY OF UTERUS

Round ligament
Utero-ovarian ligament
OVARY
FALLOPIAN TUBE
Broad ligament
FIMBRIATED
EXTREMITY
FIMBRIA
OF TUBE
OVARICA
Lower
part of broad ligament
OS UTERI
OS EXTERNUM
VAGINAL WALL, DIVIDED AND
REFLECTED
VAGINA, ANTERIOR WALL
borne children. The upper portion, or body, presents two surfaces, three borders,
and two angles. The anterior surface is almost flat, and is covered by a layer of
FIG. 636.-THE POSTERIOR SURFACE OF THE UTERUS. (After Sappey.)

BODY
ISTHMUS-
EXTRA-VAGINAL CERVIX-
INTRA-VAGINAL CERVIX-
OS
VAGINAL WALL
-FALLOPIAN TUBE
Edge of peritoneum of
Douglas's pouch
CERVICAL ATTACHMENT OF VAGINA
peritoneum which is reflected at the level of the isthmus upon the bladder, forming
a shallow utero-vesical pouch which is occupied by coils of small intestine. The

THE UTERUS
1083
posterior surface is distinctly convex, and covered in its whole extent by a layer of
peritoneum which is prolonged downwards over the neck and for a short distance
upon the posterior wall of the vagina before undergoing reflexion upon the rectum
to form the recto-vaginal pouch, or pouch of Douglas. The superior border, or
base, is thick and rounded, and is covered by the peritoneum which passes from
FIG. 637.-FRONTAL SECTION OF THE VIRGIN UTERUS. (After Sappey.)
OVIDUCT
UTERINE WALL
CAVITY OF BODY-
OS INTERNUM
UTERINE WALL-
CAVITY OF CERVIX WITH ARBOR VITAE-
OS EXTERNUM
VAGINAL WALL·
the anterior to the posterior surface. The lateral borders, slightly convex and
running downwards and inwards, correspond to the line of attachment of the
peritoneal folds called the broad ligaments. The superior angles, at the junction of
the superior with the lateral borders, give attachment to the oviducts or Fallopian
tubes. The term fundus is loosely applied to the upper part of the body.
FIG. 638.-SAGITTAL SECTION OF THE VIRGIN UTERUS. (After Sappey.)
FUNDUS
CAVITY OF BODY
OS INTERNUM
-REFLEXION OF PERITONEUM
CAVITY OF CERVIX
POSTERIOR FORNIX
POSTERIOR LIP
ANTERIOR LIP
-ANTERIOR FORNIX
OS EXTERNUM
The cervix is cylindrical in section, wider in the middle than above or below,
and may be divided into three portions, an upper supravaginal zone, a middle
zone of vaginal attachment, and a lower intravaginal zone, the os uteri. The
supravaginal zone, representing about one-half of the neck behind and two-thirds
in front, is in relation anteriorly with the bladder; posteriorly it is covered with
1084
THE FEMALE REPRODUCTIVE ORGANS
the peritoneum of the anterior wall of the pouch of Douglas, and at the sides it
is connected with the broad ligament, in which lie the uterine vessels and the
ureter, the latter at a distance of a little over half an inch. The zone of vaginal
attachment is obliquely set, extending higher behind than in front, and has a
depth of about one-fifth of an inch. The intravaginal zone, or os uteri, is
covered with mucous membrane continuous with that of the vagina. It presents
the external aperture of the uterine cavity, usually in the form of a transverse
fissure, about a quarter of an inch in length, bounded by two prominent labia,
anterior and posterior, both of which are in contact with the posterior wall of the
vagina. The anterior lip is the thicker, the shorter, and the lower; the posterior
lip is longer on account of the greater height of the posterior vaginal fornix. After
childbirth the labia usually become notched and irregular.
Dimensions. The size of the uterus varies within wide limits. Its average
length in the nulliparous adult is about three inches, and its greatest breadth about
an inch and a half, but in women who have borne children these dimensions
are about one-fifth greater. Its weight averages seven drachms in nullipara, nine
to twelve drachms in multipara.
Direction. The direction of the uterine axis is undoubtedly variable, and it is
probable that observations made after death are open to misinterpretation. It
appears to coincide under ordinary circumstances with the long axis of the body,
both in the recumbent and erect postures, but may be inclined forwards to the
extent of 15° or 20° when the bladder is empty, or may be deflected to the right
when the rectum is full.
Variations in form according to age.-In young children the body is but
slightly developed in proportion to the cervix, and the prominence of the intra-
vaginal segment is relatively great. In the virgin uterus of a young adult the
length is about equally divided between body and cervix, but after childbirth the
body never returns to its original size, and its length when involution is complete
is nearly double that of the neck. In old age the entire organ undergoes atrophy.
The cavity of the uterus is reduced to a fissure by the antero-posterior flattening
of the walls. It is divisible into two segments, that of the body and that of the
neck. The shape of the cavity of the body is that of a triangle with concave sides
(in the virgin) and three open angles. At the two superior angles are the orifices
of the oviducts, and the lower angle presents the os uteri internum or aperture
of communication with the neck. The walls are smooth, and moistened with
mucus.
The cavity of the neck is fusiform, terminating in the os internum above, and
in the os externum below. The superior opening is circular, the inferior usually
in the form of a transverse fissure. The mucous lining of the anterior and posterior
walls presents ridges which bear some resemblance to those of the vagina, but are
dependent upon the arrangement of the innermost layers of the muscular wall, and
not upon a simple plication of the mucous membrane. The whole length of each
wall is traversed by a longitudinal nearly median ridge or stem, from which pass
a number of branches in an outward and slightly upward direction.
The
figure formed by these folds is designated by the name of arbor vita uterina; it is
most marked in the young, and tends to effacement after repeated parturitions.
The cavity usually contains a plug of alkaline mucus.
Structure. The uterus is composed of three coats-an outer sero-fibrous, a
middle muscular, and an inner mucous. The serous membrane covers the upper
half or two-thirds of the anterior surface, the whole of the supravaginal portion of
the posterior surface, and the summit. The lower portion of the anterior wall is
separated from the bladder by cellular tissue continuous with the subperitoneal
fascia, and a thin layer of the same structure may be demonstrated over the lower
part of the posterior surface and laterally into the base of the broad ligament on


THE UTERUS
1085
either side between the two peritoneal laminæ. Owing to this disposition of the sub-
serous tissue, the whole of the cervix uteri may be amputated without encroaching
upon the peritoneal cavity.
The muscular coat constitutes the greater part of the thickness of the organ.
The arrangement of the fibres is very complex, but a fairly satisfactory division
into three layers may be demonstrated:-a thin outer layer, longitudinal in
direction, continuous with the muscular fibres of the oviducts, vagina, round,
ovarian, and utero-sacral ligaments, and with the muscular expansion in the broad
ligaments; a middle layer, circular in direction, very thick, and intermingled with
large venous plexuses in the body of the uterus, the innermost strands forming
sphincteric rings around the os internum and around the orifices of the oviducts;
and a thin internal layer, longitudinal in the body, and producing the ridges of the
arbor vitæ in the cervix.
The mucous membrane of the body is smooth and pale, pierced by innumerable
tubular glands, and lined with cylindrical ciliated epithelium. The ciliary motion
is from within outwards. The mucous membrane of the cavity of the neck is
FIG. 639.--THE BROAD LIGAMENT AND ITS CONTENTS, SEEN FROM THE FRONT.
(After Sappey.)

PAROVARIUM
AMPULLA OF FALLOPIAN TUBE
FIMBRIATED
EXTREMITY
OF TUBE
FIMBRIA OVARICA
Round ligament
Ligament of ovary
FALLOPIAN TUBE
EXTERNAL ANGLE OF UTERUS
Anterior peritoneal lamina
thicker and is plicated in the manner already described; its epithelium is cili-
ated down to the external opening, but there undergoes a transition into the
squamous laminated epithelium which covers the intravaginal portion of the os.
Many racemose mucous glands open into the furrows of the arbor vitæ, and these are
liable to pathological changes which cause them to assume a vesicular character,
when they are sometimes known under the fanciful name of ovula Nabothi.
Ligaments. The so-called ligaments of the uterus are of two kinds, peritoneal
and muscular.
The peritoneal ligaments are six in number: two lateral, two anterior, and two
posterior.
The lateral or broad ligaments (fig. 639), called also alæ vespertilionis from
their fancied resemblance to the wings of a bat, are formed by a duplicature of
peritoneum extending from the sides of the uterus and vagina transversely out-
wards to the sides of the pelvis. The two layers of peritoneum are continuous above
and form the free border of the fold, but diverge laterally and below, where they
pass on to adjacent structures. Each ligament presents two surfaces and four
1086
THE FEMALE REPRODUCTIVE ORGANS
borders. The superior or free border is represented by the summit of the plication,
which turns around the oviduct and follows a sinuous course towards the side of
the pelvis, its outermost extremity lying external to the fimbriated extremity of the
Fallopian tube and forming a sharp fold, the ligamentum infundibulo-pelvicum,
which conveys the ovarian vessels. The internal border is attached to the sides of
the uterus and vagina, the two lamina separating to transmit the utero-vaginal
vessels, and muscular bands, which pass from the uterus into the peritoneal fold.
The inferior border is attached to the levator ani and recto-vesical fascia; its
laminæ are separated by fat-bearing cellular tissue (subperitoneal) which gives
passage to vessels and nerves and to the ureter; and the anterior layer is much
shorter than the posterior, owing to the higher level of its point of reflexion. The
FIG. 640. DIAGRAMMATIC SECTION OF THE BROAD LIGAMENT.
PERITONEUM REFLECTED OVER SUMMIT OF LIGAMENT

FALLOPIAN TUBE
TUBAL BRANCH OF OVARIAN VESSELS
PAROVARIUM
OVARY
Ovarian artery
Round ligament with
funicular vessels
POSTERIOR SURFACE
Connective tissue and un-
striped muscle (utero-
pelvic band)
URETER
Uterine veins
Uterine artery
Base of ligament

external border lies against the obturator fascia, and transmits the uterine vessels
and the round ligament.
The structures enclosed between the two layers of the broad ligament are:-
(1) The ovary and its ligament, the former projecting from the posterior lamina and
invested by a modified epithelium; the latter, composed of unstriped muscular
fibre, passing between the side of the uterus and the inner or lower extremity of the
Ovary. (2) The Fallopian tube, lying at the upper margin immediately beneath the
point of continuity of the two lamina; its outer fimbriated extremity turned back-
wards and inwards to the ovary, and attached by one of the fringes to the outer
or lower end of the organ. It does not reach quite to the pelvic wall. (3) The
round ligament, a muscular band running downwards and outwards, forming a
ridge beneath the anterior lamina, and eventually passing to the internal inguinal
ring and through the inguinal canal into the labium. (4) Foetal relics: (a) the
parovarium, a group of twelve to twenty effete tubules of the Wolffian body lying

THE UTERUS
1087
close to the attached border of the ovary, bearing a certain resemblance in plan
to the vasa efferentia of the testicle, and joining a kind of collecting tube above.
(b) The duct of Gartner, a canal representing the lower part of the Wolffian duct,
but seldom persistent in the human subject. When present it opens upon the vulva
near the urinary meatus. (c) A few scattered imperfectly developed tubules in the
neighbourhood of the parovarium, also representing traces of the Wolffian body.
(d) The hydatid of Morgagni, a long pediculated vesicle occasionally dependent
from the fimbriae of the tubes, is believed to be a relic of the Müllerian duct.
(e) Small pedunculated cysts often found on the posterior layer of the broad ligament
and derived from the parovarium. (5) The uterine, ovarian, and funicular vessels,
anastomosing near the angle of the uterus; and the uterine plexus of nerves.
(6) A quantity of loose adipose cellular tissue lying between the muscular and other
structures and the serous membrane, and in continuity with the subperitoneal fascia
of the pelvis. (7) Involuntary muscular fibres passing from the obturator fascia to
FIG. 641.-SECTION OF THE PELVIS SHOWING THE LIGAMENTS
OF THE UTERUS.

OS PUBIS
Obturator internus.
Obturator fascia.
Subperitoneal
tissue
Utero-pelvic.
ligament
Peritoneum.
Sacro-sciatic.
ligament
RECTUM
Utero-sacral,
ligament running
forward into recto-
uterine ligament
33
SYMPHYSIS
-Prevesical fat
BLADDER WALL
VESICAL CAVITY
Peritoneum of
utero-vesical
pouch
-Utero-vesical
ligament
Broad ligament
UTERUS
Recto-vaginal
pouch of Douglas
Vessels
URETER
SACRUM
become attached to the sides of the uterus and vagina, ensheathing the vessels and
serving as a support to the uterus. They may be compared with the fibro-muscular
subperitoneal bands supporting the third stage of the duodenum, the transverse colon
and small intestines, and are essentially sustentacular in relation to the viscera and
to their vessels and nerves.
The posterior peritoneal or recto-uterine ligaments are two serous folds which
run backwards from the intraperitoneal portion of the cervix uteri and vagina to
become continuous with the peritoneal investment of the second stage of the
rectum. They form the lateral boundaries of the pouch of Douglas, and between
their layers lie muscular utero-sacral ligaments, comparable to the expansion in
the broad ligaments, with loose connective tissue and a number of anastomosing
branches of the uterine and hæmorrhoidal vessels.
The anterior peritoneal or utero-vesical ligaments are two ill-defined folds
which pass one on each side from the cervix uteri to the bladder.
The muscular ligaments lying between the peritoneal folds are four pairs:
1088
THE FEMALE REPRODUCTIVE ORGANS
three in the broad ligaments, the round or utero-inguinal, the utero-ovarian, and
the utero-pelvic, and one in the posterior ligaments, the utero-sacral. They have
already been briefly referred to.
The round or utero-inguinal ligament (fig. 639) is a cord, about five inches in
length, attached to the uterus just below the Fallopian tube, and there continuous
with the superficial uterine fibres. From this point it runs obliquely downwards,
outwards, and forwards, immediately beneath the anterior layer of the broad
ligament, to reach the pelvic wall; it then loops around the curve of the deep
epigastric artery on the inner side of the external iliac artery, and enters the inguinal
canal at the internal ring. In its course through the canal it is supplemented by a
set of striped fibres, some derived from the muscular walls of the abdomen, others
apparently of independent origin; and it may be accompanied by an invagination of
peritoneum, the canal of Nuck, which is constant in the foetus and not infrequently
persistent during childhood and even adult life. The ligament then gives off a few
of its newly acquired striped fibres to the pillars of the ring and to the pubic spine,
and, emerging from the external ring, finally breaks up into a number of delicate
fasciculi which become lost amongst the interlobular connective tissue of the large
pad of fat which occupies the labium majus.
In structure it is composed of unstriped muscle with areolar and elastic tissue,
reinforced in the inguinal canal by striated muscular fibres and funicular vessels
and nerves. The funicular artery, conveyed by the round ligament, is a branch of
the superior vesical. It is accompanied by a plexus of veins, and anastomoses in
the labium with branches of the external pudic, and at the superior angle of the
uterus with the uterine and ovarian.
The utero-sacral ligaments (fig. 641) are flat muscular bands, extending from the
highest part of the cervix uteri, where they are more or less continuous with the
uterine fibres in the recto-uterine peritoneal folds, to the sides of the sacrum
opposite the lower border of the sacro-iliac synchondroses. They run one on each
side of the rectum near the junction of the first and second stages of this portion of
the intestine, closely connected with its muscular coat, and more anteriorly are in
lateral relation with the pouch of Douglas.
The utero-pelvic ligaments (fig. 641) are the expansions of muscular tissue
already described in connection with the broad ligament. They radiate from the fascia
over the obturator internus to the sides of the uterus and vagina, and ensheathe
the utero-vaginal vessels and nerves.
The utero-ovarian ligaments (fig. 639), or ligaments of the ovaries, are short
rounded cords continuous with the uterine fibres at the superior angle of the
organ behind the Fallopian tube, and joining externally the inner end and attached
border of each ovary. These various ligamentous structures all serve to main-
tain the normal position of the uterus. In addition, the utero-ovarian ligament
aids in the fixation of the ovary, and the round and utero-pelvic ligaments form
protective sheaths for vessels and nerves.
THE FALLOPIAN TUBES OR OVIDUCTS
The Fallopian tubes (fig. 639) represent the upper extremities of the Müllerian
ducts, and may probably be regarded as cornua uteri both in structure and morpho-
logy. They are two trumpet-shaped tubes structurally continuous with the
superior angles of the uterus, and running between the two layers of the broad
ligaments to become closely connected with the ovaries, partly by direct attachment,
partly by a peculiar contiguity. Each duct opens internally into the uterine cavity,
and its external orifice establishes a continuity between the tubo-ovarian mucous
membrane and the peritoneum, but under normal circumstances is closely applied


THE FALLOPIAN TUBES
1089
to the surface of the ovary, and receives the ova which are detached from the gland,
transmitting them to the uterine cavity. It is about four and a half inches in
length, straight, narrow, and somewhat cord-like at its uterine end for a distance
of about an inch and a half; flexuous, and irregularly dilated in the rest of its
length as far as its free extremity, where it becomes expanded into a trumpet-
shaped mouth, fringed by a circle or circles of diverging villous processes or fimbriæ,
one of which, the fimbria ovarica, or tubo-ovarian ligament, is attached to the
outer extremity of the ovary. One or two little cystic pediculated appendages, like
the hydatid of Morgagni in the testicle, may also be appended to the mouth. The
aperture (ostium abdominale) in the middle of this expansion is very small, not
more than half a line or a line in diameter, but its mucous membrane may be
prolonged for some distance along a furrow in the tubo-ovarian ligament.
The narrow extremity, or isthmus, has a diameter of about an eighth of an
inch, the dilated portion or ampulla measures about a fifth of an inch, and the
terminal expansion exclusive of its fringes has a width of about a quarter to a
third of an inch, the free fimbriæ ranging in length from two-fifths to three-
fifths of an inch, while the fimbria ovarica attains an inch or even two inches.
Accessory fimbriated extremities are occasionally met with.
FIG. 642.--THE BROAD LIGAMENT AND ITS CONTENTS, SEEN FROM THE FRONT.
(After Sappey.)


AMPULLA OF FALLOPIAN TUBE
ерито
PAROVARIUM
FALLOPIAN TUBE
EXTERNAL ANGLE OF UTERUS
FIMBRIATED
EXTREMITY
OF TUBE
Round ligament
Ligament of ovary
FIMBRIA OVARICA
Anterior peritoneal lamina
Position. The normal position and direction of the ovary is still doubtful, and
the course of the duct necessarily shares in this uncertainty. There is, however, reason
to believe that it does not assume in the living subject the position represented
in anatomical diagrams. This will be referred to in the description of the ovary.
Structure. The tube has four coats-serous, cellular, muscular, and mucous.
The serous coat, represented by the fold at the free border of the broad ligament,
is incomplete, like that of the small intestine, the muscular tunic being uncovered
by peritoneum for about one-fourth or one-fifth of its circumference along the
line of attachment of the two serous laminæ, and hence a rupture of the duct may
lead to an escape of its contents either into the peritoneal cavity or into the inter-
serous space. The cellular coat is a kind of adventitia, rich in vessels, and continu-
ous with the subperitoneal tissue of the broad ligament. The muscular coat, about
the sixtieth of an inch in thickness, consists of circular and longitudinal fibres;
the latter for the most part sparingly distributed outside the former, but near the
4 A
1090
THE FEMALE REPRODUCTIVE ORGANS
outer extremity of the tube appearing also as an innermost layer. The circular
layer is most attenuated near the fimbriated extremity. The mucous membrane is
characterised mainly by its plications. The folds are longitudinal in direction, and
relatively simple in the isthmus, where the cavity appears as a stellate fissure when
cut across; but in the ampulla the multiplication of surface is very complex, and in
a transverse section presents a deceptive appearance of branching tubular glands
within the depth of a thick mucosa. At the fimbriated extremity of the tube, the
plications are continued on to the fringes. The epithelium is cylindrical and
ciliated, the motion being towards the uterus. At the trumpet-shaped extremity it
passes by transition into the pavement epithelium of the serous membrane. The
subepithelial tissue contains a longitudinal muscularis mucosa.
THE OVARIES
The ovary (fig. 635) is a paired organ which projects strongly from the posterior
surface of the broad ligament. Its longest diameter averages an inch and a half, its
greatest breadth about three-quarters of an inch, its thickness about half an inch;
and its weight is ordinarily about 100 grains. The right is usually a little larger
than the left.
Form, position, etc.-The typical shape resembles that of a broad almond.
In anatomical preparations it appears as a horizontal appendage to the back of the
broad ligament with an anterior attached border, a posterior free border, superior
and inferior surfaces, an inner extremity connected with the utero-ovarian liga-
ment, and an outer extremity receiving the fimbria ovarica of the Fallopian tube:
it is most probable however that the position is different when the organs are in
situ under normal circumstances. Symington in his examination of frozen sections
in children found the ovary lying in a sagittal plane against the side wall of the
pelvis with its long axis nearly vertical, so that its surfaces were internal and external,
its borders anterior and posterior, and its extremities upper and lower, while the
Fallopian tube ran upwards along the anterior attached border of the gland, then
arching backwards above its upper extremity to end in the fimbria; and where the
fimbriæ are fully developed they may embrace the posterior free border, and thus
the tube is wound almost completely around the gland, leaving only the lateral
surfaces exposed. The external surface is said to lie against the pelvic wall in a
hollow between the internal iliac artery and vein. The organ when enlarged may
be felt through the vagina, and, better, through the rectum, and its position with
regard to the surface is indicated by a point about two inches to the inner side of
the anterior superior spine of the ilium. The surfaces and free border are of a dull
white, and after puberty are scarred by breaches of surfaces due to the dehiscence
of ripe ova; the attached border is pierced by the ovarian vessels and nerves which
lie between the layers of the broad ligament, and their point of entrance is termed
the hilum.
Structure. The ovary consists of a parenchyma and a kind of capsule, or
tunica albuginea. The latter, unlike the tunica albuginea of the testis, is a
modification of the stroma of the gland, and does not exceed the two-hundred-and-
fiftieth of an inch in thickness; it is covered with an epithelium (columnar)
differing in character from that of the serous membrane with which it is connected.
The true gland-structure is a mass of connective tissue and unstriped muscle with
vessels and nerves. It s very vascular in the neighbourhood of the hilum, where
the veins are peculiarly large and closely set, and is condensed into a kind of cortex
beneath the albuginea. The cortex is about half a line in thickness, and consists
THE OVARIES
1091
of interlacing bundles of white fibrous tissue, which pass insensibly into the faintly
fibrillated tunica albuginea, and enclose multitudes of small vesicles called ovisacs,
or Graafian follicles, in which the ova are developed.
The majority of the ovisacs are microscopic, but as they ripen and approach the
surface they increase in dimensions, and may even attain the size of a large white
currant. Their rupture leads to the scarring already mentioned, and the empty cap-
sule slowly disappears when impregnation has not occurred; but, under the influence
of the vascularisation of the organs during pregnancy, it may undergo a remarkable
development and form a yellow plicated body known as the corpus luteum.
FIG. 643.-DIAGRAM OF THE ARTERIES AND LYMPHATICS OF THE FEMALE GENERATIVE
Lymphatics of broad ligament
(to lumbar glands)
ORGANS.

OVARY
FALLOPIAN TUBE
Funicular lymphatics
(to inguinal glands)
Uterine and vaginal
lymphatics (to pelvic
glands)
19600
Uterine artery
Vaginal arteries
Ovarian
artery
Funicular
artery
Transverse perineal artery
Vulvar lymphatics
(to inguinal glands)
VESSELS AND NERVES OF THE UTERUS AND ITS APPENDAGES

The vessels are the uterine, ovarian, and funicular, all of which are paired.
The uterine artery (fig. 643), a branch of the internal iliac, runs from its origin in a
downward direction along the pelvic wall as far as the base of the broad ligament;
then, crossing horizontally towards the cervix uteri in front of the ureter, it gives
off some small vaginal and vesical branches, and runs upwards in a serpentine
course close to the side of the body of the uterus, supplying transverse branches to
the anterior and posterior walls of the organ. These anastomose with their
fellows across the middle line, one larger branch opposite the junction of the body
and cervix, forming with the corresponding vessel of the other side the arterial
circle of Huguier.' Finally they communicate at the upper angle with the terminal
twigs of the ovarian and funicular arteries. The uterine veins are of very large
size, and on leaving the uterus form a plexus in the muscular tissue of the
proad ligaments, at length joining a trunk which runs side by side with the artery
to end the internal iliac vein.
The ovarian artery, arising from the aorta (like the spermatic in the male),
4A 2
1092
THE FEMALE REPRODUCTIVE ORGANS
crosses the common iliac artery, and is conducted into the broad ligament by
the ligamentum infundibulo-pelvicum (page 1086), which extends to the outer end
of the oviduct. It breaks up into two divisions: (1) The tubal, which runs along the
lower border of the oviduct where the peritoneal layers of the tube separate, and
sends numerous branches to it; and (2) the ovarian proper, a large serpentine
vessel which gives off many large branches into the hilum of the gland, and then
passes to the angle of the uterus, where it ends by anastomosing with the uterine
and funicular arteries.
The ovarian veins, very largely developed about the hilum of the ovary,
appear as a plexus in the broad ligament, and, reaching the margin of the plexus,
assume a pampiniform arrangement around the artery. The right ends in the
vena cava, the left in the renal vein.
The funicular artery is an offset of the vesical. It joins the round ligament
at the internal ring, and divides into ascending and descending branches, the
former running backwards in the substance of the ligament as far as the angle
of the uterus, where it communicates with the ovarian and uterine; the latter
passing with the ligament through the inguinal canal into the labium, there
anastomosing with the external pudic. It is accompanied by its vein.
The lymphatics (fig. 643) of the uterus and Fallopian tubes form plexuses in the
mucous membrane, in the muscular walls, and beneath the peritoneum. Those of the
ovary originate in the perifollicular tissue around the Graafian vesicles, and escape
at the hilum. The efferent vessels from these three organs may be divided into
three groups with intercommunicating territories. (1) The first, including those of
the body of the uterus, those of the ovary, and those of the Fallopian tube, unite by
the side of the ovarian vessels and run with the veins to terminate in the prevertebral
ganglia in front of the aorta and vena cava; (2) the second, those of the cervix uteri,
form two trunks which run along the base of the broad ligament with the
uterine vein to end in the pelvic glands which lie beneath the bifurcation of the
iliac artery; (3) the third, those of the round ligament, follow this structure and
end in the inguinal or lower iliac glands. Here as elsewhere the lymphatics are
collateral with the veins.
The nerves of the uterus are derived from the third and fourth sacral, the hypo-
gastric plexus of the sympathetic, and from the renal plexus, which also supplies
the ovaries and oviduct.


DEVELOPMENT OF THE GENITO-URINARY ORGANS
There is at first a period in the growth of the embryo during which there is no indica-
tion of any provision either for the generative or for the urinary function. A little later
the rudiments of a genito-urinary apparatus are laid down, but there is as yet no appear-
ance of sexual differentiation. Finally, a third stage in the formative process is occupied
by the evolution of the organs characteristic of the masculine or feminine type, and the
completion of the glandular and other structures which provide for the secretion, storage,
and ultimate expulsion of the urine from the body. It will be seen that in the course of
these developmental changes certain of the structures concerned appear and assume their
permanent characters gradually and without alteration of plan; others, originally employed
for purposes unconnected with the genito-urinary system, become adapted to take their place
in this section of the economy; others belonging to the system from the first are brought
into a special condition of functional activity only to undergo conversion to a different use
later on; while others again may, according to the sex assumed by the foetus, either dwindle
into useless relics without ever taking any share in the work of the body, or may become
elaborated into important and efficient parts of the reproductive organism.
The earliest appearance is that of a tube called the Wolffian duct, which opens by
its hinder extremity into a cloaca or common outlet for the intestinal and urinary
passages. From the fore part of this duct is developed a temporary organ, the
pronephros, or head-kidney, in the form of vascular glomeruli. Behind this soon appear a
number of tubes, which open at right angles into the mid portion of the duct, and constitute

DEVELOPMENT OF GENITO-URINARY ORGANS
1093

the mesonephros, mid-kidney, or Wolffian body. Still farther back, from the posterior end of
the duct, springs the metanephros, or hind-kidney, a mesoblastic growth around a hollow
branching protrusion from the duct, with which tubules and glomeruli subsequently
become connected. The pronephros quickly disappears in the higher vertebrates; the
mesonephros, which reaches its maximum development by the sixth week, soon ceases to
discharge its renal function, and either becomes a useless relic in the broad ligament of the
female pelvis, or undergoes transformation into an essential part of the male generative
apparatus; while the metanephros becomes developed into the permanent kidney.
The ureter and uriniferous tubules probably originate as special outgrowths from the
posterior part of the Wolffian duct. The morphology of the suprarenal body is somewhat
doubtful, but it is probable that the medulla is a derivative of the sympathetic system, and
hence of epiblastic origin; while the cortex is a mesoblastic development in connection with
the fore end of the Wolffian duct. It is at first larger than the kidney, but the latter
attains an equal bulk by the tenth week, and then continues to increase, becoming
considerably the greater by the end of foetal life; but even at birth the suprarenal bodies
are proportionately much larger than in the adult.
FIG. 644.-DIAGRAM OF THE PRIMITIVE GENITO-URINARY ORGANS BEFORE
DIFFERENTIATION OF SEX. (After Henle.)

KIDNEY-
MÜLLER'S DUCT-
GENITAL GLAND-
WOLFFIAN BODY-
(tubular structure not shown)
URACHUS
INTERIOR OF BLADDER
URETER.
Round ligament.
WOLFFIAN DUCT.
UNITED MÜLLERIAN DUCTS-
OPENINGS OF WOLFFIAN DUCT-
SINUS URO-GENITALIS.
PENIS CLITORIS.
-OPENINGS OF URETERS
-URETHRA
-OPENING OF MÜLLERIAN DUCT
The urinary bladder appears in the second month as a transformation of the pedicle of
the allantois, a structure which has already done service in conveying the vessels of the
embryo to the placenta. The allantois is a hypoblastic sac invested by a layer of mesoblast,
and communicating with the hind gut. That portion of it which lies within the body
becomes dilated at its central part into the urinary bladder, but remains narrow at both
extremities, forming in front the urachus; and behind, the whole urethra in the female,
and the upper part of the prostatic urethra in the male.
The generative apparatus is developed from the Wolffian ducts and from two other
paired structures closely related to these, but of somewhat later formation-the Müllerian
ducts and the genital glands.
From the Wolffian body its tubules and its duct are formed, in the male, the whole of
the excretory tubes outside the body of the testicle, namely, the vasa efferentia, the coni
vasculosi, the tube of the epididymis, the vas deferens, the ejaculatory duct, and the
paradidymis (the organ of Giraldès). In the female the structure dwindles away, leaving
its vestiges as the parovarium and the duct of Gartner (the latter being occasionally
demonstrable in the human subject).
1094
THE URINARY ORGANS
The
The genital gland arises as a ridge, partly mesoblastic and partly due to a thickening of
an epithelial layer, the germinal epithelium, on the inner side of the Wolffian body.
cells, at first indeterminate, soon become differentiated to form the Graafian follicles and ova
in the female, and the epithelium of the seminiferous tubes in the male; the rest of the ovary
or testicle being developed from the mesoblast of the ridge. The gland is at first attached
to the Wolffian body. The latter is itself fixed to the posterior wall of the abdominal cavity
by a duplicature of peritoneum called the mesorchium, or mesovarium, from which a little fold
containing muscular fibre is prolonged downwards to become the gubernaculum testis in the
male, or, after connection with the uterus, the round ligament in the female.
FIG. 645.-DEVELOPMENT OF THE URINO-GENERATIVE ORGANS, FEMALE TYPE.
(After Henle.)
(The parts formed from the Müllerian duct in this and the succeeding diagram are
indicated by horizontal shading; those formed from the Wolffian body and duct, by
diagonal cross-hatching.)

KIDNEY
OVARY
FALLOPIAN TUBE
PAROVARIUM
URETER
URACHUS
BLADDER
Round ligament.
CRUS CLITORIDIS
BULBUS VESTIBULI-
VULVAR CLEFT-
UTERUS
VAGINA
URETHRA
GLAND OF BARTHOLIN
CLITORIS

The Müllerian duct begins as a slender cord lying parallel to, and on the outer side of,
the Wolffian duct. It becomes canalised and opens distally into the cloaca. After a time
it fuses with its fellow mesially a short distance above the terminal aperture, and the con-
joint tube is bound together with the adjacent Wolffian ducts into a kind of stem called the
genital cord. In the male the Müllerian duct never appears to discharge any function, and
its useless relics are to be traced in the sinus pocularis and hydatid of Morgagni; but in
the female it gives rise to nearly the whole of the internal apparatus of generation; its
upper extremity, above the line of fusion in the human subject, forming the oviduct and its
hydatid appendage, the conjoint tube developing the uterus and vagina. Variations in
the point of fusion of the two ducts may lead to the abnormality of a two-horned uterus,
or even a double uterus and vagina. Exceptionally Müller's duct may form a rudimentary
uterus in the male. In such cases the testes are well developed, but the penis remains
very small.
The external genitals are developed about the cloacal outlet common to the genito-
urinary and intestinal canals. The first change is the appearance of a genital eminence,

DEVELOPMENT OF GENITO-URINARY ORGANS
1095
the future clitoris or penis, at the ventral extremity of the cloacal fissure about the fifth
or sixth week. A fortnight later the cloaca is divided by a transverse septum into
two parts, a dorsal or anal, and a ventral or uro-genital (uro-genital sinus); the septum
itself persisting as the perinæal body in the female, and the portion of the perinæum lying
between the scrotum and anus in the male. Its absence or incomplete development
accounts for certain congenital malformations well known to teratologists. The uro-genital
sinus next undergoes changes which give the external stamp of sex. At first the urethra
opens into the sinus behind the genital prominence. In the female this remains perma-
nent, the lips of the sinus expand into the labia majora; two ridges within the sinus,
extending one on each side as high as the genital prominence, form the nymphæ; and a
little semilunar fold at the entrance of the vagina shows itself in the fifth month and
becomes the hymen; while the genital eminence ceases to enlarge and remains as the
FIG. 646.-DEVELOPMENT OF THE URINO-GENERATIVE ORGANS, MALE TYPE.
(After Henle.)

KIDNEY
EPIDIDYMIS-
BODY OF TESTICLE-
GUBERNACULUM-
VAS DEFERENS-
URACHUS
URETER
BLADDER
VESICULA SEMINALIS.
SINUS POCULARIS.
EJACULATORY DUCT-
PROSTATE-
MEMBRANOUS URETHRA-
BULB
SCROTUM
PROSTATIC URETHRA
-CORPUS SPONGIOSUM
-CORPUS CAVERNOSUM
GLANS
clitoris. In the male the evolutionary processes go farther. The margins of the uro-genital
sinus fuse in the middle line to close in a prolongation of the urethra on the ventral aspect
of the genital eminence and to form the scrotum, the process being concluded about the
fifteenth week; finally, a pouch of peritoneum makes its way on each side through the
abdominal wall into the corresponding half of the scrotum, and into this the testicle
ultimately descends, guided by the gubernaculum (page 1063). The glands of Cowper
or Bartholin in both sexes are formed by involutions of epithelium near the root of the
rudimentary clitoris or penis.
Should the process of mesial fusion fail, the urethra may present a fistulous opening on
its ventral side, or may remain cleft from the meatus upwards for a greater or less distance.

1096
THE URINARY ORGANS
In the more aggravated forms the defect of union involves the scrotum also, and leads to a
spurious hermaphrodism in which is perpetuated a superficial resemblance to the female
genitals, the simulation being made greater by the imperfect descent of the testicles.
All these congenital defects are clearly accounted for by ascertained facts in morphology;
but there is a malformation which our present knowledge does not satisfactorily explain-
that known as 'extroversion of the bladder,' in which a non-closure of the ventral parietes
below the umbilicus coincides with a fissure in the anterior wall of the allantoic bladder,
and leads to an extrusion of the posterior wall of the viscus. Mr. Shattock suggests that
the condition is perhaps the result of an undue extension forwards of the cloacal fissure;
but the problem cannot yet be regarded as solved.
THE PERINEUM
The term perinæum (epi, vaiw) has been variously applied by anatomists--
firstly, in its original and general meaning, to the soft parts connected with the
pelvic outlet; secondly, to the anterior or genito-urinary segment only of these
parts; and thirdly, to the tissues separating the vulvo-vaginal and ano-rectal
passages. It is here employed in the first and broader sense, the expression
'perinæum proper' being used for the second application, and that of perinæal
body' for the third.
The outlet of the pelvis is a lozenge-shaped space bounded in front by the
symphysis and subpubic ligament, behind by the tip of the coccyx, and on each
side by the conjoined rami of os pubis and ischium, the tuber ischii, and the inferior
border of the great sacro-sciatic ligament. The latter structure is overlapped to a
variable extent by the gluteus maximus, which also covers the tuber ischii when
the thighs are extended; but the glutei are merely accessory to the true boundaries.
The dimensions of the outlet in the male and female are given in page 156.
The further anatomy of the parts differs in the two sexes.
THE MALE PERINEUM
The integument of the perinæum is pigmented, beset with scattered hairs, and
its sebaceous and sudoriparous glands are largely developed. Its deeper layers
contain an abundance of smooth muscular fibre continuous with the dartos of the
scrotum, and these are so disposed around the anal margin as to corrugate the
skin into radiating folds during their contraction.
The landmarks of the region are for the most part well-defined. The
symphysis in front is obscured by the root of the penis, which may be traced
backwards as a soft median prominence as far as a point an inch anterior to the
anus. On each side the pubic and ischial rami may be felt running outwards and
backwards to expand into the ischial tuberosity, which is uncovered by the gluteus
maximus when the thigh is flexed. Extending backwards and inwards from the
tuberosity may be detected, in thin subjects, the resistance of the great sacro-sciatic
ligament; and still more posteriorly the coccyx is felt in the middle line immediately
beneath the skin. The anal aperture, surrounded by radiating furrows, lies a short
distance in front of the coccyx, and on each side of it is a depression called the
ischio-rectal fossa, the superficial aspect of which depends upon the amount of fat
which occupies it.
The perinæum is divided arbitrarily into two parts by a line drawn transversely
between the two ischial tuberosities an inch in front of the anus. The anterior
portion is called the perinæum proper, the posterior the ischio-rectal region. This
line, however, does not coincide exactly with the true anatomical boundary as
revealed by dissection

THE MALE PERINEUM
1097
The ischio-rectal region comprises the parts surrounding the anus and the
ischio-rectal fossæ.
The removal of the integument exposes the sphincter muscle of the anus in the
middle line, and on each side, between this and the lateral boundary of the perinæum,
the external aperture of the ischio-rectal fossa.
The sphincter ani externus is a voluntary muscle surrounding the anus, and
attached, in front to the tendinous centre of the perinæum (where it meets the bulbo-
cavernosi, the superficial transversi perinæi, and some fasciculi of the levatores ani);
behind to the tip of the coccyx. Its fibres are closely connected with the skin, and
superficial bundles pass forwards by the sides of the anus, a few decussating with

FIG. 647.-THE MALE PERINEUM. (Modified from Hirschfeld and Leveillé.)

BULBO-CAVERNOSUS
uperficial triangular ligament
ISCHIO-CAVERNOSUS
Muscles of thigh
INFERIOR PUDENDAL NERVE
SUPERFICIAL PERINEAL NERVE!
INFERIOR HEMORRHOIDAL NERVE
CUTANEOUS BRANCH OF FOURTH SACRAL
Sphincter ani
Gluteus maximus
TUBEROSITY OF ISCHIUM
Great sacro-sciatic ligament
Levator ani
Superficial transversus perinæi
each other across the middle line, and some appear to cross directly over to the
opposite side, and around the anus as an annular sphincter. They are pierced
by radiating bands of the longitudinal layer of the muscular wall of the rectum,
which become lost in the deep layers of the integument.
The external sphincter is in relation superficially with the integument, deeply
with the levatores ani and internal sphincter; on the outer side with the fat of the
ischio-rectal fossa; and internally with the lower portion of the 'internal sphincter'
(a thickening of the circular muscle of the rectum), and to a small extent with the
rectal mucous membrane. It is supplied by the inferior hæmorrhoidal branches
of the internal pudic artery; its veins, of large size and very liable to varicose
1098
THE URINARY ORGANS
dilatation, terminate in the pudic vein; its lymphatics open into the inguinal glands;
and its nerves are derived from the perinæal, the pudic, and the fourth sacral.
Action.-The external sphincter, by virtue of its elasticity, gives some passive
aid to the internal sphincter in maintaining the closure of the anus and the
retention of the contents of the rectal cul-de-sac under ordinary conditions; but
its active and more important function is to close the anal aperture firmly during
the contraction of the levatores ani and other constrictor muscles of the abdomino-
pelvic cavity in powerful muscular efforts not connected with defæcation (as in
vomiting, urination, parturition, expiration, etc.). This it effects partly through the
approximation of the opposite sides of the anus by its longitudinal fibres, and
partly by the ring-like contraction of its circular fibres. It also aids in flexing the
coccyx, and in fixing the tendinous centre of the perinæum during the contraction
of the bulbo-cavernosi.
THE PELVIC FASCIA AND MUSCLES
In order to understand the constitution of the ischio-rectal fosse and their
relation to adjacent parts, it is necessary to review the muscular elements of the
pelvic wall, and the arrangement of the pelvic fasciæ.
FIG. 648.-DIAGRAM OF THE PELVIC FASCIA.

Iliac fascia
Obturator fascia.
'White line'-
Recto-vesical fascia-
Obturator fascia-
Ischio-rectal fascia.
Alcock's canal with.
pudic vessels
Transversalis fascia-
Psoas
-Abdominal muscles
-ILIAC CREST
-Iliacus
BORDER OF ACETABULUM
-Apex of ischio-rectal
fossa
-Levator ani
-ISCHIAL TUBEROSITY
-Sphincter ani
The osseo-ligamentous framework of the walls of the true pelvis is constituted
by the two ossa innominata below the ilio-pubic line and posterior border of the
pubic crest, by the sacrum and coccyx, and by the sacro-sciatic, sacro-iliac, and
interpubic ligaments, and the obturator membrane. Supplementing these structures
on each side of the median line, are four muscles: the obturator internus, the pyri-
formis, the coccygeus, and the levator ani, together with their fascial investments.
The obturator internus and pyriformis have already been described (pages 375,
377). The fascia covering the inner aspect of the former muscle bears a very
important relation to the intrapelvic structures.
The obturator fascia (figs. 648, 650) is attached above to the ilio-pubic line,

PELVIC FASCIE AND MUSCLES
1099
as far back as the sacro-iliac joint and to the posterior lip of the crest; below,
to the back of the symphysis, the inner lip of the lower border of the ischio-
pubic ramus, and the inner border of the ischial tuberosity; and behind it skirts
the osseous border of the great sciatic notch as far as the ischial spine, but at the
lesser sciatic notch passes out of the pelvis with the muscle, and appears in the
post-femoral region of the thigh. At its borders it is closely related to the fascia
iliaca above, the fascia of the pyriformis behind, and the deep triangular ligament
below. Its outer surface is in contact with the muscular fibres of the obturator
internus; its inner surface is divided into two portions by a curved band of fibres
called the 'white line' or arcus tendineus, extending from the inner surface of the
ischial spine to the back of the os pubis, a little external to the symphysis. The
upper or pelvic segment above the white line is separated from the pelvic viscera
by subperitoneal tissue; the lower or ischio-rectal segment, below the line, enters
into the formation of the outer wall of the ischio-rectal fossa. This portion forms
a sheath (canal of Alcock) for the pudic vessels and nerves about an inch above the
inner margin of the tuber ischii. The fascia gives off from its inner surface at
FIG. 649.-MUSCLES OF THE FLOOR OF THE PELVIS.

SACRUM
Pyriformis
CCCCYX-
Levator ani (divided
below the white line")
Space for obturator.
internus
RECTUM
PROSTATE
SYMPHYSIS
Passage for gluteal
vessels and nerve
Pyriformis
Passage for sciatic
and pudic vessels.
and nerve
ISCHIAL SPINE
Coccygeus
Cellular interval
Levator ani
Capsule of prostate,
and pubo-prostatic
ligaments
the white line two thin lamina: one, the recto-vesical, to the visceral surface of the
levator ani; the other, the ischio-rectal, to the parietal aspect of the same muscle.
The levator ani muscle (figs. 648, 650), with its fellow of the opposite side,
constitutes the greater part of the muscular floor of the pelvis, and acts as a septum
between the pelvic cavity and the ischio-rectal fossa. It arises anteriorly from the
back of the os pubis, just external to the attachment of the pubo-vesical muscle,
posteriorly from the inner side of the ischial spine below the origin of the coccygeus,
and between these two points from the whole length of the white line.' Its fibres
form a flat plane of considerable strength, and pass downwards, backwards, and
inwards to their insertion, the most posterior to the tip of the coccyx; those next
in order to join the opposite muscle in a median raphe extending from the coccyx
to the tendinous centre of the perinæum, and the rest to the side of the rectum,
interlacing with the longitudinal layer of the muscular wall of the gut. Its two
surfaces may be termed visceral and parietal; the former, looking forwards as well
as upwards, is invested by a layer of fascia, the recto-vesical, and is further separated
from the lower part of the bladder by subperitoneal tissue; the parietal surface,


1100
THE URINARY ORGANS
covered by a fascia, the ischio-rectal or anal, forms the greater part of the outer
wall of the ischio-rectal fossa. The anterior and posterior borders of the muscle are
free (and here the two investing fascia become continuous with each other). The
anterior border crosses the side of the prostate, and is connected with the corre-
sponding part of the opposite muscle by fibrous and smooth muscular tissue, which
passes between the prostate and rectum. The posterior border is separated from
the anterior margin of the coccygeus by an indistinct cellular interspace.
In the female the anterior fibres of insertion are connected with the side of the
vagina, interlacing with the longitudinal fibres of its muscular tissue without
becoming actually inserted into the passage.
The levator ani is supplied by twigs of the inferior hæmorrhoidal vessels and
nerves, and receives also branches from the fourth and fifth sacral nerves.
Action.-The special action from which the muscle derives its name has been
questioned by Rüdinger, who believes that its essential function is to compress the
FIG. 650.-DIAGRAM SHOWING LINES OF ATTACHMENT OF THE FASCIE
AND MUSCLES OF THE PELVIS.
GREATER SACRO-SCIATIC-
NOTCH
ISCHIAL SPINE WITH AT-
TACHMENTS OF COCCY-
GEUS AND LEVATOR ANI
LESSER SCIATIC NOTCH
Course of white line'.
-Obturator fascia
-Levator ani
Obturator fascia.
Deep triangular
ligament
Posterior border of
perinæal ledge
Transversus perinæi-
SYMPHYSIS
Subpubic ligament
Superficial triangular
ligament
Fascia of Colles
ISCHIO-CAVERNOSUS
AND CRUS
rectum. A study of the direction of the fibres, however, leaves little doubt that the
result of the contraction of the muscle as a whole, and in association with its fellow,
is to draw forwards the coccyx and elevate the pelvic floor and viscera, and thus
lessen the long diameter of the abdomino-pelvic cavity and aid in the compression
of the abdominal and pelvic viscera. Its action as a compressor of the rectum is
probably unimportant, but it is possible that it exercises some influence upon the
circulation in the prostatic plexus and in the large pelvic veins which occupy the
recess between the muscle and the viscera, and may also assist in the expulsion of
the prostatic secretion by direct lateral compression of the organ. In the female it
may constrict the lower end of the vagina, where the passage lies between the
free borders of the two muscles.
The coccygeus is a thin and rather unimportant plane of muscular fibres,
supported by and blending intimately with the lesser sacro-sciatic ligament. It

PELVIC FASCIE AND MUSCLES
1101
arises from the inner surface of the ischial spine above the levator ani, and
passes backwards and inwards, expanding to become inserted into the sides of the
coccyx, the lateral sacro-coccygeal ligament, and the last two pieces of the sacrum.
Its visceral surface looks almost directly forwards, and is covered by a continuation
of the recto-vesical fascia. Its parietal surface is in contact with the lesser sacro-
sciatic ligament. Its superior border is separated from the inferior border of the
pyriformis by the vessels and nerves which escape from the pelvis below the latter
muscle. Its inferior border is related to the posterior border of the levator ani.
The muscle is often pierced by filaments of the fourth and fifth sacral and coccygeal
FIG. 651.-MUSCLES OF THE FLOOR OF THE PELVIS.
(A portion of the ischial and pubic bones sawn away.)

Aperture for
superior gluteal
vessels and nerve.
SACRUM
Pyriformis
Aperture for
sciatic and pudic
vessels and nerve.
ISCHIAL SPINE
COCCYX
Coccygeus
Coccygeal fibres
of levator ani
Fibres of leva-.
tor ani
Sphincter ani-
RECTUM
White line' of
obturator fascia
Pubic attach-
ment of levator
ani
PROSTATE
Tendinous
centre of
perinæum
nerves, which supply it and form a kind of plexus on its pelvic surface. It aids
the levator ani in drawing forwards the coccyx.
The recto-vesical fascia may be regarded as a lamina detached from the
obturator fascia at the level of the upper border of the white line.' From this
point it extends upon the pelvic surface of the levator ani and coccygeus to become
reflected upon the viscera immediately related to the muscular floor of the pelvis,
namely, the prostate and bladder (forming the capsule of the former and the 'true
ligaments' of the latter), the vasa deferentia and vesiculæ seminales, the lower part
of the rectum, and, in the female, the vagina and uterus. Its visceral portion is
1102
THE URINARY ORGANS
easy to trace in the immediate neighbourhood of its reflexion, but it becomes less
distinct as it recedes from this point, and at length is undemonstrable.
The ischio-rectal or anal fascia, originating at the white line below the fascial
attachment of the levator ani, closely invests the parietal or ischio-rectal surface
of this muscle, and that of its neighbour, the coccygeus, to blend in the region of
the anus with the deep fascial covering of the external sphincter. In front it passes
above the perinæal structures, becoming continuous with the superior triangular
ligament (a prolongation of the obturator fascia), and meeting with the recto-vesical
fascia, at the anterior border of the levator ani; while behind it extends backwards
for a variable distance to join again with the obturator fascia. In this way the two
fascia, obturator and ischio-rectal, close in the ischio-rectal fossa above, in front,
and behind, but leave it widely open below.
The ischio-rectal fossa (figs. 647, 648, 652, 653) are two deep interspaces, one on
each side, left by the divergence of the obliquely directed muscles of the pelvic floor
(levator ani and coccygeus) from the vertical pelvic wall. Each fossa is bounded
FIG. 652.-SAGITTAL SECTION THROUGH THE PERINEAL LEDGE AND ISCHIO-RECTAL
FOSSA TO THE LEFT OF THE MIDDLE LINE. (Diagrammatic.)

Pyriformis
Coccygeus
Obturator fascia
Deep triangular
ligament
Subperitoneal tissue
Fascia transversalis
OS PUBIS
Obturator internus
Fascia lata of thigh-
Muscles of thigh
לי.
SACRUM
NERVES
Great sacro-sciatic
ligament
Lesser sacro-sciatic
ligament
Gluteus maximus
Levator ani with its
fasciæ
Ischio-rectal fossa
Deep perinæal inter-
space with deep trans-
versus perinæi
Superficial triangular
ligament
Superficial perinæal interspace
with muscles of penis
externally by the obturator internus below the level of the white line, the corre-
sponding portion of the obturator fascia (with Alcock's canal and the pudic vessels
and nerves), and the os innominatum; and internally by the levator ani and
Coccygeus and the ischio-rectal fascia. Superiorly, the vertical outer wall is
joined by the sloping inner wall where the ischio-rectal fascia joins the obturator
fascia, so that the space is angular A in outline in frontal section. So far all
anatomists are agreed, but the remaining boundaries require further investigation.
If the finger be introduced into the fossa, it will meet in front the line of junction
of the triangular ligaments with the fascia of Colles. Deep or superior to this will
be found an anterior recess of considerable size extending forward nearly as far
as the symphysis, between the superior triangular ligament and the under surface of
the levator ani, and limited internally by the prostate and pubo-prostatic ligaments,
and externally by the pubic and ischial rami. Behind will be felt the border of the
great sacro-sciatic ligament, and above this a posterior recess running backwards
for a variable distance towards the sacrum. Both of these deep extensions are lined
by the ischio-rectal and obturator fascia, and filled with fat and connective tissue.



PELVIC FASCIE AND MUSCLES
1103
The ischio-rectal fossa must then be described as an anvil- or T-shaped cavity with
anterior and posterior recesses running the one above the perinæal ledge, the other
above the sacro-sciatic ligaments.
Contents. The ischio-rectal fossa is filled with loose adipose tissue continuous
with the subcutaneous fat of the buttock, and traversed from without inwards by
the inferior hæmorrhoidal branches of the pudic artery, and by the associated veins
and some twigs of the internal pudic nerve passing to the sphincter ani and adjacent
skin and mucous membrane.
The veins are usually somewhat dilated near the anal margin, and when
morbidly enlarged constitute the condition known as hæmorrhoids or piles.
Near the posterior border of the triangular ligaments the pudic vessels and
nerves give off their superficial perinæal branches, which almost immediately
enter the superficial perinæal interspace.
A small branch of the fourth sacral nerve may be seen turning over the back of
the space to reach the anal integument.
FIG. 653.-SECTION SHOWING THE ISCHIO-RECTAL FOSSA IN ITS RELATIONS TO
THE PELVIC VISCERA.

OS PUBIS
Muscles.
Levator ani with recto-vesical,
and ischio-rectal fasciæ
Obturator internus
Internal pudic vessels and
NERVES in obturator fascia
TUBER ISCHII
Ischio-rectal fossa with its
anterior and posterior ex-
tensions
Gluteus maximus
300
SYMPHYSIS PUBIS
-Pubo-prostatic ligaments
-Prostatic plexus
PROSTATE
Capsule of prostate formed
by recto-vesical fascia
-Fat
RECTUM INVESTED BY RECTO-
VESICAL FASCIA
THE PERINEUM PROPER
The perinæum proper (fig. 647, 652), considered apart from the portion of the
common integument which covers it in, is a curious triangular ledge of tissue
stretched almost horizontally across the angular interval between the two ischio-
pubic rami. It is pierced by the urethra (and also by the vagina in the female), and
comprises three strong fascia which enclose within two interfascial spaces the root
of the penis with the muscles appended to it, the compressor urethræ muscle,
Cowper's glands, and a number of vessels and nerves. Above it lie the prostate and
levatores ani with their fasciæ, and the anterior recess of each ischio-rectal fossa.
The perinæal integument has already been described. On removal of the skin
with its dartos and the superficial layers of superficial fascia, a deeper plane of fascia
will be exposed, connected firmly with the ischio-pubic rami. This is the fascia of
Colles (the deep layer of the superficial perinæal fascia), the most superficial of the
three true perinæal fasciæ.
The fascia of Colles is a fibrous lamina of considerable strength. It is attached


1104
THE URINARY ORGANS
on each side to the lower margin of the ischio-pubic ramus and to the ischial
tuberosity; behind, it turns around the posterior border of the superficial transversus
perinæi muscle to fuse with the posterior borders of the superficial and deep
triangular ligaments and form the free border of the 'perinæal ledge'; ante-
riorly, it becomes continuous with the external fascial investment of the scrotum
and the fascial covering of the penis.
It is between this layer and the inferior triangular ligament that extravasation
of urine is especially prone to occur in rupture of the urethra. From its connections
it will be seen that the extension of the fluid would be arrested posteriorly and
laterally by the connection of the fascia of Colles with the triangular ligaments and
with the ischio-pubic rami; but it spreads freely beneath the integuments of the
scrotum and of the penis as far as the neck of the glans, and eventually may
reach the surface of the abdomen, but is prevented from descending below the
groin by the connection of the abdominal fascia with Poupart's ligament.
Superficial perinæal interspace (figs. 647, 652, 654).-Detaching the fascia of
Colles from its connections, the dissector opens the superficial interfascial space and
FIG. 654.-DIAGRAM OF THE SUPERFICIAL AND DEEP TRIANGULAR LIGAMENTS.
Subpubic ligament with aperture for
dorsal vein of the penis
Apertures for dorsal artery and nerve
of the penis
Dorsal vein of penis
CRUS PENIS
Aperture for artery of corpus
cavernosum
Superficial triangular ligament
Ischio-cavernosus
Aperture for artery.
to bulb
Urethral aperture
Aperture for Cow-.
per's duct
Position of bulb-
Apertures for super-
ficial perineal ves-
sels and nerve
DORSAL NERVE
Anterior layer of triangular
ligament
Dorsal artery of penis
Deep triangular
ligament
Artery of corpus
cavernosum
Artery to bulb
Pudic veins
DORSAL NERVE
POSITION OF COWPER'S
GLAND
-Internal pudic artery
Fascia of Colles,
turned backwards
Posterior border
of perinæal ledge
(junction of trian-
gular ligaments
with fascia of
Colles)
exposes its contents, namely:-(1) The crura of the corpora cavernosa with the
ischio-cavernosi; (2) the bulb of the corpus spongiosum with the bulbo-cavernosi ;
(3) the capriciously scattered fibres of the superficial transversi perinæi; (4) the
arteries of the corpora cavernosa and the dorsal arteries of the penis with their
associated veins and lymphatics; (5) the dorsal nerves of the penis; and (6) the
superficial perinæal vessels and nerves. The roof of the space (the so-called floor)
is formed by the inferior triangular ligament.
The transversi perinæi, the crura penis with the ischio-cavernosi, and the bulb
with the bulbo-cavernosi, have been already described (page 1072). Each of the
muscles named has a fascial sheath of its own, distinct from the fascia of Colles.
The artery of the corpus cavernosum enters the crus immediately after piercing
the inferior triangular ligament; the dorsal artery of the penis, reaching the inter-
fascial space more anteriorly with the dorsal nerve, runs forwards to the dorsum of
the united corpora cavernosa to take its place between the vein and nerve;
the superficial perinæal vessels and nerve given off from the internal pudic trunks
in the ischio-rectal fossa enter the interfascial space near the free border of the
perinæal ledge. These divide into two sets of branches, posterior or deep, to

THE PERINEUM PROPER
1105
the penile muscles, and anterior or superficial to the scrotal and perineal integument;
the latter piercing the fascia of Colles and the scrotal investment continuous with
it to reach the skin.
The superficial perinæal interspace then may be said to contain the root of the
penis, with the muscles, vessels, and nerves connected with it.
Inferior triangular ligament ('the anterior layer of the triangular ligament')
(fig. 652).-On removing the contents of the superficial interspace the dissector
exposes the under surface of the inferior or superficial triangular ligament. This
structure forms almost a horizontal plane in the erect posture of the body,
and consists of strong bands of fibrous tissue, running for the most part in a
transverse direction across the subpubic arch to be attached firmly to the ischio-
pubic rami above the line of attachment of the fascia of Colles and of the penile
muscles. Anteriorly, it is separated from the subpubic ligament by an interval
which transmits the dorsal vein of the penis; posteriorly, it blends with the fascia of

FIG. 655.-VERTICAL FRONTAL SECTION OF THE PELVIS, SHOWING FASCIE.
(Modified from Braune.)

BLADDER-
UVULA VESICE-
PROSTATE
VERUMONTANUM-
Levator ani-
MEMBRANOUS
URETHRA
Pudic vessels-
PUBIC ARCH-
Fascia of ischio-.
cavernosus
CRUS PENIS
BULB
BULBO-CAVER-
NOSUS WITH
ITS FASCIA
Integument of
perinæum
White line
Subperitoneal fat
-Obturator internus
Ischio-rectal fascia
LOS INNOMINATUM
Recto-vesical
fascia,
parietal and visceral
layers
Obturator fascia
Obturator membrane
ISCHIO-RECTAL FOSSA
-Deep triangular lig.
Deep transversus
perinæi
-Superficial triangular
ligament
Muscles of thigh
Ischio-cavernosus
Muscles of thigh
Colles and with the superior triangular ligament to form the hinder border of the
perinæal ledge; and superiorly it is intimately related to the deep transversus perinæi
muscle. It is pierced by:-(1) The urethra, about an inch and a quarter below the
symphysis; (2) the ducts of Cowper's glands, one on each side of the posterior
part of the urethral openings; (3) the arteries of the bulb, somewhat external to
the last; (4) the arteries to the corpora cavernosa, more anteriorly and close to
the lateral attachment of the ligament; (5) the dorsal arteries and nerves of the
penis, at the margins of the ligament near its apex. The dorsal vein with some
accompanying lymphatics runs through the interspace between the triangular
and subpubic ligaments (fig. 654).
Deep perinæal interspace (figs. 620, 652, 654).-If the superficial triangular
ligament be now detached, the deep perineal interspace will be laid open. This
space is somewhat wedge-shaped in sagittal section, in consequence of the manner
in which the two triangular ligaments approach each other before their union
at the posterior border of the perinæal ledge. It is occupied by the following
structures:-
4 B

1106
THE URINARY ORGANS
(1) The membranous urethra, surrounded by its annular sphincter of smooth
muscular fibres.
(2) Cowper's glands, seen as two white pea-like bodies, one on each side of the
posterior segment of the urethra. Their ducts pierce the superficial ligament.
(3) The internal pudic arteries, lying close to the ischio-pubic rami imbedded
in the fibres of origin of the compressor urethræ muscle, giving off each an artery
to the bulb as well as some twigs to Cowper's gland and to the muscular tissue
surrounding the urethra, and terminating by division into the artery to the corpus
cavernosum, and the dorsal artery of the penis. These branches with the associated
veins have been seen to pass through the superficial triangular ligament into the
superficial perinæal interspace.
(4) The pudic veins, accompanying the arteries. Their tributaries form a
plexus around the urethra, and in the substance of the fibres of the deep transversus
perinæi. This plexus, which is often largely developed in old persons, receives the
veins of the corpus spongiosum and corpora cavernosa, and communicates freely
with the dorsal vein of the penis, and through this with the prostatic plexus.
(5) The pudic lymphatics, accompanying the veins and terminating in the
pelvic glands.
(6) The dorsal nerves of the penis, the terminal branches of the internal pudic
nerves, accompany the arteries; each nerve gives off filaments to the deep trans-
versus perinæi, and then pierces the fore part of the superficial triangular ligament
with the dorsal artery.
(7) The deep transversus perinæi or compressor urethræ.-The muscular
tissue of the deep perinæal space has been a source of great confusion owing to the
multiplicity of the names which have been assigned to various portions of it; but the
description given by Henie may be accepted as at once the simplest and the most
accurate. The transversus perinæi profundus of Henle is closely connected with
the superior and inferior triangular ligaments. It arises from the inner surface of
the ischio-pubic ramus, by tendinous bundles which separate to form a kind of
channel for the pudic vessels and dorsal nerve of the penis, close to the bone. From
this origin the greater part of the fibres run across the subpubic angle in a
transverse direction in front of and behind the membranous urethra, enclosing
Cowper's glands and the deep veins of the penis, and join a more or less indistinct
median raphe; while others pass more or less obliquely forwards in front of the
urethra and behind the dorsal vein to become attached to the pubic ramus on the
side opposite to the bony attachment. A small accessory bundle (the sagittal
layer' of Henle) may sometimes be found running directly forwards to become
inserted into the upper surface of the bulb and into the connective tissue between
the corpora cavernosa. The arrangement of the fibres differs considerably in
different subjects, and much complexity has been introduced into the study of
the muscle by the artificial segregation of certain of its parts under special
names, such as levator urethræ, constrictor urethræ, etc.
Its action is partly to compress the membranous urethra and thus assist the
expulsion of urine and semen, and partly to intercept the flow of blood through
the veins of the penis, and so aid in erection. It also exercises compression
upon Cowper's glands, and effects the discharge of their secretion during seminal
emission. It is supplied by a branch from the dorsal nerve of the penis.
The superior or deep triangular ligament (figs. 650, 652, 654) is in some sort
a prolongation of the obturator fascia across the pubic arch; the continuity of the
two fasciæ, however, being interrupted by the attachment of their deep fibres to
the inner edges of the ischio-pubic rami. Inferiorly it is in intimate relation with
the deep transversus perinæi; while superiorly it forms on each side the floor of the
anterior extension of the ischio-rectal fossa; and in the middle line it is separated
from the apex of the prostate by a prolongation of recto-vesical fascia, and by a

THE FEMALE PERINEUM
1107
layer of smooth muscular fibre, the prærectalis of Henle, in which end the greater
part of the anterior longitudinal fibres of the rectum.
It is pierced by the pudic artery and vein and the dorsal nerve of the penis.
The dorsal vein of the penis passes between it and the subpubic ligament.
THE FEMALE PERINEUM
The female perinæum (fig. 656) differs from that of the male, partly in the
perforation of the whole of its fascial and muscular structures in the middle line by
the vulvo-vaginal passage, and partly in the adaptation of the perinæal muscles to
the modified conditions of the external genital apparatus. The corpora cavernosa
FIG. 656.-DIAGRAMMATIC REPRESENTATION OF THE PERINEAL STRUCTURES
IN THE FEMALE.

ISCHIO-PUBIC ARCH-
CRUS CLITORIDIS WITH.
ISCHIO-CAVERNOSUS
BULBO-CAVERNOSUS.
COVERING BULBUS
VESTIBULI
Superficial trian-.
gular ligament
OGLANS CLITORIDIS
WITH PREPUCE
PARS
INTERMEDIALIS
Mucous mem-
brane of
vestibule
MEATUS URINARIUS
-BULBUS VESTIBULI
GLAND OF
BARTHOLIN
Sphincter ani
penis are represented by the relatively diminutive corpora clitoridis; the ischio-
cavernosi are proportionately reduced in size, but differ in no other material
respect; the corpus spongiosum is divided into two lateral segments, which are
represented by the bulbi vestibuli and partes intermediales; and the two bulbo-
cavernosi are separate, and appear in an attenuated form, spread over the erectile
tissue as an attenuated plane of fibres, the compressor vaginæ, which is often
difficult to recognise on dissection; while the median raphe uniting the two
muscles in the male gives place to the genital fissure. The superficial transversi
perinæi differ only in size from those of the male; but the deep transversus
perinæi is of course cleft by the vagina, and its fibres are relatively thin and weak
and in great part unstriped. The glands of Bartholin, although morphologically
identical with Cowper's glands, are less deeply placed.
The greater development of the connective tissue structures between the genital
canal and the third stage of the rectum, leading to the formation of the perinæal
body, is also a peculiarity of the female (fig. 619). The perineal body is triangular
in sagittal section, and bounded in front by the vulvo-vaginal wall, behind by the
anterior wall of the rectum, and below by the integument between the posterior


4 B2

1108
THE MAMMARY GLANDS
vulvar commissure and the anal aperture. It consists of a strong meshwork of
connective tissue freely intermingled with fibres of elastic tissue and unstriped
muscle, and is traversed by the various muscles which meet at the tendinous
centre of the perinæum. It becomes stretched to a remarkable degree during the
passage of the child's head in labour, but is saved from rupture by its strength
and elasticity.
THE MAMME
The mammary glands are two pectoral organs which secrete the milk in the
female, but remain permanently rudimentary and functionless in the male.
The female mamma (in which term is included the gland with its investing
integumentary structures) is seen in its typical adult form as a more or less hemi-
spherical eminence upon the front wall of the chest over the third, fourth, fifth,
and sixth ribs, and extending transversely from the border of the sternum to the
anterior margin of the axilla. It is surmounted near its middle by a small wart-
like process, the mammilla or nipple, which lies in the centre of a circular area of
altered skin called the areola.
FIG. 657.-THE FEMALE MAMMA DURING LACTATION. (After Luschka.)
Mammilla
Ampulla of
duct
Acini of gland
- Areola
Adipose
loculus
Gland loculus
The secreting organ consists of an aggregation of ten to sixteen compound
racemose glands, the ends of which open separately upon the summit of the nipple.
These component elements are quite distinct in the dissected breast as so many
lobes of somewhat pyramidal form, with their bases at the periphery and the apices
converging towards the mammilla. They are held together and supported by a
fibrous capsule, which sends inwards deep interlobular processes to form a loculated
framework for the glandular elements, and superficial processes running to the
skin and enclosing fat-containing spaces or adipose fossæ. The deep aspect of the
capsule also encloses other fat-spaces, and is attached to the deep fascia by loose
connective tissue, the bands of which may be separated by large lymph-spaces,
the so-called submammary bursæ.' It is the fat lying in the subcutaneous adipose

THE MAMME
1109
fossæ and between the gland lobules that gives smoothness and uniformity of surface
to the breast, and when it becomes absorbed during lactation or in conditions of
emaciation, the lobular structure of the gland is distinctly manifest.
Structurally each of the component lobes may be regarded as a modified sebaceous
gland, and hence an appendage of the skin. Each is provided with a single
excretory tube (lactiferous or galactophorous duct), which on approaching the
nipple is dilated into a sinus or ampulla, and finally ends by a constricted orifice
at the apex of the nipple. The acini and smaller tubes are lined with cubical
epithelium, which becomes replaced by columnar cells in the excretory ducts.
Accessory glands of small size-half a line to two lines in diameter, and to the
number of five to fifteen-are normally found under the skin of the areola, and
open on to the summit of the nipple.
The gland as a whole is not circular in outline, but usually presents three
cusps-one towards the sternum, sometimes overlapping the bone; the others
towards the axilla, one above and the other below; smaller extensions, moreover,
pass from the base of the gland to the deep fascia, and may pierce it and lie upon or
in the fibres of the pectoral muscle (Heidenhain). These processes are commonly
left behind in amputation of the breast, and may form nuclei for recurrent growth
in malignant disease.
The mammilla and areola are specially modified portions of the mammary
integument. The mammilla is placed a little internal and inferior to the centre of
the gland, and points forwards and outwards. It is of somewhat conical form,
averaging about half an inch in length, and terminating by a rounded extremity
which is pierced by the orifices of the lactiferous ducts. It is of pinkish colour,
and is capable of a kind of erection under the influence of cold, mechanical
stimulus, or mental emotion. In some persons it is normally retracted into a
depression of the integument, and only projects in response to stimulation.
The areola is about an inch in diameter, and is characterised by its pigmentation,
the delicacy of its texture, the absence of subcutaneous fat, the large development
of its sebaceous and accessory milk glands, and its contractility under the influ-
ences which produce erection of the nipple. It is pink in the virgin, but during
pregnancy and lactation assumes a brownish shade. The accessory glands,
slightly marked in the virgin, form distinct prominences after impregnation
(tubercles of Montgomery).
The contractility of the nipple and areola is due to the presence of circular
and radiating fibres of unstriped muscle in the subcutaneous tissue, the former
passing into the substance of the nipple, and forming a network around the lacti-
ferous ducts. The circular fibres by their contraction cause the nipple to project;
the radiating fibres retract it.
Variations according to age and functional activity. At birth the gland is
only about one-fifth to one-third of an inch in diameter. The nipple with its
dartos is well formed, and the secreting structure is represented by slightly ramified
ducts which contain a milky fluid. Growth is slow up to the time of puberty;
after this, development progresses rapidly, but no distinct indication of subdivision
into lobes is present until impregnation takes place. Some slight engorgement of
the breast may, however, occur at the menstrual period, when a yellowish glutinous
secretion may sometimes be expelled from the ducts. In pregnancy and during
lactation the evolution of the gland-structure is remarkably active. The whole
breast enlarges, the superficial fat undergoes absorption, the vessels become dilated
and their walls thickened; the areola and nipple increase in size, and the former
becomes more or less deeply pigmented. After the end of lactation the breast
becomes smaller, but seldom resumes its original condition of smoothness, firmness,
and elasticity, and some traces of the pigmentation of the areola remain permanent.
In old age the glandular structures atrophy.


1110
THE MAMMARY GLANDS
60 The male breast differs from that of the female in the early arrest of its evolution.
It ranges in diameter from a third of an inch to an inch, and possesses an areola
and nipple, the former often beset with hairs. It is usually placed over the
fourth intercostal space a little internal to the border of the pectoralis major,
but its position is very variable, and the two glands are often unsymmetrical. A
temporary engorgement occasionally appears in early adult life, and may lead to
inflammatory complications.
Vessels and nerves. The arteries are derived from the internal mammary
through the second, third, and fourth intercostal spaces, and from the thoracic
branches of the axillary. The chief supply is given to the perforating branches of
the internal mammary, but the external mammary branch of the axillary artery
may be of large size in the female.
The veins terminate in the corresponding trunks. The superficial veins become
visibly enlarged during pregnancy and lactation.
The lymphatics accompany the veins; some terminate in the costal group of
axillary glands, and others in the retrosternal chain; and in cancer of the breast
the deep cervical glands about the subclavian vessels may become implicated as the
disease advances.
The nerves are derived from the supraclavicular branches of the cervical plexus,
and from the intercostals. The glandular twigs are traced by Eckhard to the
fourth, fifth, and sixth intercostals.
FIG. 658.-DEVELOPMENT OF THE MAMMA OF THE FEMALE EMBRYO.
(7 inches in length x 70.) (After Langer.)
ogtoo lo loredat)
Development. The breast appears about the seventh week of foetal life as a circular
epidermic ridge, enclosing a central depression, the cells of which grow inwards and form
branching tubular ducts that radiate beneath the nipple (fig. 658).
Abnormalities. Small supplementary lacteal glands, in addition to the normal
accessory structures beneath the areola, are frequently present around the margin of
the principal gland, and may be found in front of the sternum, in the axilla, and below
the clavicle, and there is reason to believe that many of the adenomata and cancers take
origin in these redundant structures (Roger Williams). Besides these, large supernumerary
mammæ, having all the characters of the typical organs, have also been met with in
various situations-in the axilla, over the back, the abdomen, and even on the thigh.
These are in all probability atavistic. Absence of the mamma is extremely rare.
The nipples may be double, or even triple on each breast, or may be wanting
altogether.
In a few instances an abnormal development of the gland tissue has been known to
occur in the male, and milk has been secreted in sufficient quantity to nourish an infant.
A slight and temporary enlargement of the gland about the period of puberty is not
infrequent.
bioget out add
SECTION X
ON SURGICAL
AND
TOPOGRAPHICAL
ANATOMY
By W. H. A. JACOBSON, M.A., M.B., M.CH.OXON, F.R.C.S.
ASSIS TANT SURGEON, GUY'S HOSPITAL; LECTURER ON ANATOMY IN THE MEDICAL SCHOOL.

SUPERFICIAL ANATOMY OF THE HEAD AND NECK
THE HEAD AND FACE
Bony landmarks.-These should be studied with the aid of a skull, as well as on
the living subject. In the middle line behind is the external occipital protuberance,
or inion, the thickest part of the vault, and corresponding internally with the
meeting-point of six sinuses. From this point the nuchal lines pass out towards
the mastoid processes, and indicate the course of the lateral sinuses, which, after
running horizontally outwards, turn downwards in the mastoid bone. About two
inches and three-quarters above the external occipital protuberance is the lambda,
or meeting of the coronal and lambdoidal sutures (posterior fontanelle), small
and triradiate in shape (fig. 660). The point of junction of the lambdoidal and
squamous sutures, the asterion, is placed about three-quarters of an inch behind
and half an inch above the upper part of the posterior border of the mastoid
(fig. 661). The bregma, or junction of the coronal, sagittal, and, in early life, the
frontal suture (anterior fontanelle, large and lozenge-shaped), lies just in front of
the centre of a line drawn transversely over the cranial vault from one external
auditory meatus to the other (fig. 661). The pterion, or junction of the frontal,
parietal, temporal, and sphenoid bones, lies in the zygomatic fossa, one and a half
to two inches behind the external angular process of the frontal, and about the
same distance above the zygoma (fig. 661). This spot also gives the position of
the trunk and the anterior and larger division of the middle meningeal artery.
The zygoma can be traced backwards to its roots in front of the ear, while from
its anterior extremity the finger, carried upwards along the outline of the malar,
traces the temporal ridge along the side of the skull which marks the upper
limit of the temporal fossa, and the attachments of the temporal muscle and
fascia. In the temporal fossa lie the muscle, and the deep temporal vessels and
nerves. Above the zygoma can be felt the contraction of the temporal; and below,
that of the masseter muscle; the former less distinctly owing to its covering of
fascia, attached below by two layers to the upper border of the zygoma. In the
zygomatic fossa, lying inside the zygoma, are the lower part of the temporal, and

1112
SURGICAL AND TOPOGRAPHICAL ANATOMY
the two pterygoid muscles, together with the internal maxillary vessels, and the
mandibular division of the nerve, and their branches.
FIG. 659.-THE SKULL IN SAGITTAL SECTION.
BREGMA
DCCIPITAL
POINT
BASION
FIG. 660.-THE CRANIUM AT BIRTH.
OPHRYON
SUB-NASAL
POINT
The anterior inferior angle of the parietal bone, and its great importance as a
landmark, has already been given. The posterior inferior angle of this bone
(grooved by the lateral sinus) lies a little above and behind the base of the

THE SKULL
1113
mastoid, on a level with the roots of the zygoma (fig. 661). The lateral sinus
will be indicated by a line passing from the external occipital protuberance to a
point one inch behind the external auditory meatus.
The average thickness of the adult skull-cap is about one-fifth of an inch
(Holden). The thickest part is at the external occipital protuberance, where the
bone is often three-quarters of an inch in thickness. The thinnest part of the skull
vault is over the temporal part of the squamous. The extreme fragility of the skull
here is partly compensated for by the thickness of the soft parts; of these, the
pericranium is alone thinner than elsewhere, while its intimate connection with
the bones makes cephalhæmatoma less frequent here. (Tillaux.)
FIG. 661.-THE SKULL. (Norma lateralis.)
STEPHANION
PTERION
Temporal
Masseter
Temporal
Buccinater
Buccinator
TEMPORAL
RIDGES
External pterygoid
Masseter
ASTERION
In front, the circumference of the bony orbit can be traced in its whole extent.
The supraorbital notch lies at the junction of the inner and middle thirds of the
supraorbital arch. When this notch is a complete foramen, its detection is much
less easy.
Above the supraorbital arch is the supraciliary ridge, and higher still
the frontal eminence. From the supraorbital notch a line drawn downwards and
slightly outwards, so as to run between the two bicuspid teeth in each jaw, passes
over the infraorbital and mental foramina. (Holden.)
THE BONY SINUSES.-The frontal. The development of these by the twentieth
or twenty-fifth year may render a fracture here much less grave in the adult
than would otherwise be the case, the inner table, if now separated from the
outer, protecting the brain. Mr. Hilton showed that the absence of any external

1114
SURGICAL AND TOPOGRAPHICAL ANATOMY
prominence here does not necessarily imply the absence of a sinus, as this may be
formed by retrocession of the internal table. In old people these sinuses may
enlarge by the inner table following the shrinking brain. Again, a very prominent
bump here does not necessarily point to the existence of a sinus at all, being due
merely to a heaping up of bone.
The communication of these sinuses with the nose accounts for the frontal
headache in ozæna, and the fact that a patient with a compound fracture opening
up the sinuses can blow out a flame held close by.
7
The mastoid sinuses are arranged in two groups, of the utmost importance in
FIG. 662.-DRAWING OF A CAST OF THE HEAD OF AN ADULT MALE.
(Prepared by Professor Cunningham to illustrate cranio-cerebral topography.)
FISSURE OF
ROLANDO
INTRA-
PARIETAL
FISSURE
POSITION OF
PARIETAL
EMINENCE
EXTERNAL
PARIETO-
OCCIPITAL
FISSURE
Lateral sinus
POSITION OF
FRONTAL EMINENCE
FISSURE OF
SYLVIUS
PARALLEL
FISSURE
MIDDLE
TEMPORAL
FISSURE
that frequent and fatal disease, inflammation of the middle ear :-(1) The antrum,'
present both in early and late life, horizontal in direction, closely adjacent to and
communicating with the tympanum. Through this bone, very thin in early life,
the trephine should be directed in opening up the mastoid cells. (2) The vertical.
This group is not developed in early life. Inflammation here brings mischief
nearer the lateral sinus and cerebellum.
The veins passing from the mastoid cells and tympanum fall into three chief
groups (a) those opening into the lateral sinus; (b) those passing through the
mastoid foramen into the occipital and scalp veins; (c) those running through the
petro-squamosal suture to the dura mater. As all these veins carry connective-
tissue sheaths, inflammation may reach-(a) the lateral sinus, causing septic
phlebitis; (b) the soft parts outside, causing cellulitis, periostitis, etc.; (c) the dura
mater and brain, leading to meningitis and abscess.

DEVI ALL THE SCALP
1115
The sphenoidal sinuses are less important surgically, but these points should
be remembered:-(1) Fracture through them may lead to bleeding from the nose,
which is thus brought into communication with the middle fossa; (2) the com-
munication of their mucous membrane with that of the nose may explain the
inveteracy of certain cases of ozæna; (3) here and in the frontal sinuses very
dense exostoses are sometimes formed.
THE SCALP. The importance of the scalp is best seen from an examination of
its layers (fig. 663). These are-(1) skin; (2) subcutaneous fat and fibrous tissue;
(3) the occipito-frontalis and aponeurosis; (4) the subaponeurotic layer of con-
nective tissue; (5) the pericranium and subpericranial connective tissue.
The first three layers are connected and move together. (1) The union of the
skin, and its density, are to enable it to meet pressure, and also to prevent it rucking
into folds. Furthermore, they account for the extreme pain of inflammation here, and
the difficulty of raising a blister on the scalp. The presence of hairs and sebaceous
glands is of much more importance than appears at first. Thus the rooting of
the former is so firm that in the case of young women the whole scalp may be
FIG. 663.-SECTION THROUGH THE SCALP, SKULL, AND DURA MATER. (Tillaux.)

Skin and super-
ficial fascia with
HAIR BULBS AND
SEBACEOUS GLANDS
Fat pellets
Occipito-frontalis
aponeurosis
-Sub-aponeurotic
connective tissue
-Pericranium
-Subpericranial
connective tissue
SKULL: DIPLOIC
TISSUE
Dura mater
Skull cavity
6
torn off by machinery. The sebaceous glands have also grave importance. If in
removing them the aponeurosis beneath is pricked or the wound becomes foul, fatal
suppuration in the dangerous area' beneath may follow. (2) The subcutaneous
fat is arranged much as in the palm, viz. tough fatty pellets are enclosed in fibrous
partitions, dipping from the skin to the third layer, and thus tying the three layers
together. (3) The occipito-frontalis and its aponeurosis have been fully described
elsewhere (page 454). (4) The subaponeurotic layer of connective tissue. The
characters of this layer are quite opposed to those of the layer of connective tissue
above the aponeurosis. It is loose, delicate, and fatless. From these result the
free mobility of the scalp, the fact that it can be torn away, and (most important
of all) the facility with which inflammatory products can spread in this layer.
The perils of pus pent up here are extreme, viz. sloughing of the scalp, or necrosis
of the bones, blood-poisoning, and meningitis, from mischief travelling along the
emissary and diploic veins (fig. 663). The continuity of the different scalp layers by
bands of connective tissue passing from the skin to the occipito-frontalis, and thence
along vessels, emissary and others, into the venous sinuses, or by the diploic
veins within the skull, will account for scalp inflammation reaching the meninges.

1116
SURGICAL AND TOPOGRAPHICAL ANATOMY
V
Of the vessels of the scalp, the arteries are peculiar in their position. Thus
they lie superficial to the deep fascia, which is here represented by the aponeurosis
(fig. 663). From this position arises the fact that a large flap of scalp may be
separated without perishing, as it carries its own blood-vessels. From the density
of the layer in which the vessels run they cannot retract and are difficult to seize,
hæmorrhage thus being free. Finally, from their position over closely adjacent
bone, ill-applied pressure may easily lead to sloughing.
The emissary veins.-These are communications between the sinuses within,
and the veins outside, the cranium. Most of them are temporary, corresponding to
the chief period of growth of the brain. Thus in early life, when the develop-
ment of brain has to be very rapid, owing to the approaching closure of its case,
a free escape of blood is most essential, especially in children, with their sudden
explosions of laughter and passionate crying.
1. Vein through the foramen cæcum, between the anterior extremity of the
superior longitudinal sinus and the nasal mucous membrane. The value of this
temporary outlet is well seen in the timely profuse epistaxis of children. Other
more permanent communications between the skull cavity and nasal mucous
membrane pass through the ethmoid and internal orbital foramina. The fact
that the nasal mucous membrane is loose and ill-supported on the turbinated
bones allows its vessels to give way readily, and thus forms a salutary safeguard
to the brain, warding off many an attack of apoplexy.
2. Vein through the mastoid foramen, between the lateral sinus and the
posterior auricular and occipital veins. This is the largest, the most constant,
and the most superficial of the emissary veins. Hence the old rule of applying
blisters or leeches over it in cerebral congestion.
3. Vein through the posterior superior angle of the parietal between the superior
longitudinal sinus and the veins of the scalp.
4. Vein through the posterior condyloid foramen between the lateral sinus and
the deep veins of the neck.
5. Vein through the anterior condyloid foramen between the occipital sinus and
the deep veins of the neck.
6. Ophthalmic vein between the cavernous sinus and the angular vein. This
vein may be the source of fatal blood-poisoning, by conveying out of reach septic
material, in acute periostitis of the orbit, or in ostitis of dental origin of the jaws.
7. Minute veins through the foramen ovale between the cavernous sinus and
the pharyngeal and pterygoid veins.
8. Communications between the frontal diploic and supraorbital veins, between
the anterior temporal diploic and deep temporal veins, and between the posterior
temporal and occipital diploic veins and the lateral sinus.
The gravity of these emissary veins and their free communications with others
is shown by the readiness with which they become the seat of septic thrombosis,
and thus of blood-poisoning, in cranial injuries, erysipelas, suppuration of the scalp,
and necrosis of the skull.
Structure of cranium.-Two layers and intervening cancellous tissue. Each
layer has special properties. The outer gives thickness, smoothness, and uniformity,
and, above all, elasticity. The inner is whiter, thinner, less regular-e.g. the
depressions for vessels, Pacchionian bodies, dura mater, and brain. Its chief
characteristics are its fragility (vitreous) and absolute inelasticity.
The diploë,
formed by absorption after the skull has attained a certain thickness, reduces the
weight of the skull without proportionately reducing its strength, and provides a
material which will prevent the transmission of vibrations.
Results of the above varying elasticity.-A blow on the head may fracture the
internal table only, the external one and diploë escaping. This is difficult to
diagnose, and thus it is impossible to judge of the severity of a fracture from

THE SKULL
1117
the state of the external table. This may be whole, or merely cracked, while the
internal shows many fragments, which may set up meningitis, or other mischief.
Anatomical conditions tending to minimise the effects of violence inflicted upon
the skull. (1) The density and mobility of the scalp. (2) The dome-like shape of
the skull. This, like an egg-shell, is calculated to bear hard blows and also to allow
them to glide off. (3) The number of bones tends to break up the force of a blow.
(4) The sutures interrupt the transmission of violence. (5) The internal membrane
(remains of foetal periosteum) acts in early life as a linear buffer. (6) The elasticity of
the outer table. (7) The overlapping of some bones, e.g. the parietal by the
FIG. 664.-THE COURSE OF THE OCCIPITAL ARTERY.
Anterior branch of
posterior auricular
Posterior branch of
posterior auricular
PAROTID GLAND, displaced
and turned up
Sterno-mastoid, cut
Auricular branch of
occipital
Rectus capitis lateralis
SPINAL ACCESSORY
NERVE
Posterior auricular
Internal jugular vein
Facial artery
HYPOGLOSSAL NERVE
Lingual artery
PNEUMOGASTRIC
NERVE
Superior thyroid artery
External branch
of occipital artery
Internal branch
of occipital
Complexus
Arteria princeps
cervicis
Superior oblique
muscle
Trachelo-mastoid, cut
Splenius capitis, cut
Meningeal branches
Sterno-mastoid branch of
occipital
Internal carotid
Sterno-mastoid
Common carotid
External carotid
Trapezius
squamous; and the alternate bevelling of adjacent bones, e.g. at the coronal suture.
(8) The presence of ribs or groins, e.g. (a) from the crista galli to the internal
occipital protuberance; (b) from the root of the nose to the zygoma; (c) the temporal
ridge from orbit to mastoid; (d) from mastoid to mastoid; (e) from the external
occipital protuberance to the foramen magnum. (9) Buttresses, e.g. malar and
zygomatic processes, and the greater wing of the sphenoid. (10) The mobility of
the head upon the spine.
Arteries. The supraorbital artery can be felt beating just above its notch
(junction of inner with outer two-thirds of supraorbital arch); the temporal itself can

1118
SURGICAL AND TOPOGRAPHICAL ANATOMY
be felt where it crosses the root of the zygoma just in front of the tragus, its anterior
branch about an inch and a quarter above and behind the external angular process of
the frontal; the occipital pulsates near the middle of a line drawn from the occipital
protuberance to the mastoid process; the posterior auricular behind the apex of the
mastoid. The external carotid lies behind the ascending ramus of the jaw. The
FIG. 665.-SCHEME OF THE FACIAL ARTERY.
Orbicularis palpebrarum muscle
Frontal branch of ophthalmic
artery
Nasal branch of ophthalmic
artery
Transverse facial artery
Zygomaticus minor
muscle
Zygomaticus-major
muscle
Buccinator muscle
Masseteric branch
Masseter muscle
Stylo-pharyngeus
muscle
Stylo-glossus muscle
Ascending palatine branch
Tonsillar branch
Facial arter
External carotid
artery
Posterior belly of.
digastric muscle
Lingual artery-
Angular artery
Levator labii superioris
et alæ nasi muscle
Infraorbital artery
Lateralis nasi artery
Levator anguli oris
muscle
Artery of septum
Superior coronary artery
Risorius muscle
Inferior coronary artery
Mental branch of inferior dental
artery
Depressor labii inferioris muscle
Inferior labial artery
Depressor anguli oris muscle
Submental artery
Branches to submaxillary gland
Anterior belly of digastric muscle
Mylo-hyoid muscle
Hyo-glossus muscle
HYPOGLOSSAL NERVE
facial crosses the jaw just in front of the masseter; if divided, both ends must be
secured here. It can be felt again a little behind the angle of the mouth, just
beneath the mucous membrane (it here gives off the coronaries, which can also be
felt if the lip is taken between the finger and thumb); and again by the side of the
nose, as it runs up to the tendo oculi. The little frontal artery is of importance, as
it nourishes the flap when a new nose is taken from the forehead.
orehead.

THE EYELIDS
1119
A line drawn from the tip of the lobule of the ear to a point midway between
the nose and upper lip gives the level of the parotid duct, which opens into the
mouth opposite the second upper molar. The sheath of the parotid, continuous
with those of the masseter and sterno-mastoid, is strong enough to cause most
exquisitely painful tension when inflammation of the gland is present. The upper
border of the gland is marked out by a line drawn along the posterior part of the
zygoma, the lower by one drawn from the angle of the jaw to the mastoid
process
(fig. 668, page 1121). The posterior border is bounded by the mastoid process, external
auditory meatus, and the sterno-mastoid; the anterior border and the socia parotidis
project to a variable degree over the masseter. The proximity of the parotid to the
styloid process, to which the pharynx is attached, accounts for deep parotid abscess
opening into the pharynx. Below the root of the zygoma, when this
process is
traced backwards, will be felt the temporo-mandibular joint; and when the mouth
is opened, the condyle will be felt to glide forwards upon the eminentia articularis.
FIG. 666.-VERTICAL TRANSVERSE SECTION THROUGH UPPER EYELID.
(After Waldeyer and Fuchs.)

Cutaneous surface just
above superior palpe-
bral fold
Orbicularis fibres, cut
across
SWEAT GLAND
FINE HAIR WITH SEBACEOUS
GLAND AT ITS BASE
Orbicularis fibres, cut
across
MODIFIED SWEAT GLAND OF
MOLL
CILIUM
CONJUNCTIVA NEAR FORNIX
Anterior layer of inser-
tion of levator pal-
pebræ superioris
Superior palpebral
muscle of Müller
Fibres from levator
passing through
orbicularis to skin
Superior vascular arch,
cut across
WALDEYER'S GLANDS
Conjunctival papillæ
over attached border
of tarsus
Musculus ciliaris
Riolani
Posterior edge of lid-
margin
OPENING OF DUCT OF
MEIBOMIAN GLAND
THE EYELIDS AND LACHRYMAL APPARATUS
The structure of the lids.-The different layers are of much practical import-
ance. (1) The skin is delicate and fatless, and contains pigment, the object of
this being to protect the eye from bright light. It helps to explain the dark
6
1120
SURGICAL AND TOPOGRAPHICAL ANATOMY
circles' of later life. (2) Areolar tissue. Owing to its looseness and delicacy, it is
very liable to infiltration, as in ascites and erysipelas. (3) Orbicularis. Paralysis
of this, the palpebral portion, leads to epiphora, the puncta being no longer kept
applied against the eye. (4) Palpebral ligament, reaching from the orbit to the tarsal
cartilage. This is usually strong enough to prevent hæmorrhage, due to fractured
base of skull, becoming subcutaneous. (5) Levator palpebræ. (6) Tarsal cartilage.
In reality, densely felted fibrous tissue. (7) Meibomian glands, lashes, and sebaceous
follicles. Localised inflammation starting in any of these three structures, especially
the last, will cause a 'stye.' The frequency with which the lid-border is the seat of
that most troublesome chronic inflammation, blepharitis, and its result'blear eye,'
is explained by these anatomical points. Its circulation is terminal and slow; half
skin and half mucous membrane, it is moister and more liable to local irritation
than the skin; while its numerous glands readily participate in any inflammation.
FIG. 667.-THE LACHRYMAL APPARATUS AND NASAL DUCT. (Bellamy.)
(Bristles are introduced into the puncta lachrymalia.)

-LACHRYMAL SAC
Tendo oculi
Valvular folds in nasa duct
INNER WALL OF ANTRUM
LOWER TURBINATED BONE Orifice of nasal duct
(8) The conjunctiva. The differing structure of the palpebral and ocular portion
has important bearings. Thus the palpebral is thick, highly vascular, and very
sensitive. To the vascularity we owe the chemosis, or hot, red, tense swelling of
purulent ophthalmia. The exquisite suffering of the same disease, or that caused
by a foreign body, is explained by the numerous nerve-papillæ. To the thickness
and abundance of the connective tissue are due the contraction and permanent
thickening which may occur in granular lids. The so-called granulations, met with
in this disease on the palpebral conjunctiva, are really little nodules of hypertrophied
lymphoid follicles, or mucous glands, which abound here.
The position of the lachrymal puncta should be noted: owing to their back-
ward direction the lids must be previously everted. The puncta are kept open by a
minute fibrous ring. The lachrymal sac is the most important of the lachrymal
apparatus, from its disfiguring diseases; it lies in a bony groove, between the
nasal process of the maxilla and the lachrymal bone. The tendo oculi crosses
it a little above its centre. Thus two-thirds of the sac are below the tendon, and
in suppuration the opening is made below it also. The angular artery ascends

THE EYE
1121
on the nasal side of the sac. The manipulation of a probe along the lachrymal
passages should thus be practised :-The lower lid being drawn outwards and
downwards by the thumb, the probe is passed vertically into the punctum, then
turned horizontally and passed on till it reaches the inner wall of the sac. It is
then raised vertically, and pushed steadily along the duct downwards, and a little
outwards and backwards, till the floor of the nose is reached.
THE MOUTH
On the floor, on either side of the frænal fold of mucous membrane, are the
orifices of Wharton's ducts, marked by minute papillæ. In dividing the frænum
for tongue-tie, the scissors should be kept close to the bone, so as to avoid the ranine
vessels. Of these, the ranine vein can be seen beneath the mucous membrane; the
artery lies close to it, but deeper. Two diverging folds indicate the position of these
FIG. 668.-SIDE OF THE FACE AND MOUTH CAVITY, SHOWING THE THREE
SALIVARY GLANDS.

SOCIA PAROTIDIS
DUCT OF SOCIA
PAROTIDIS
DUCT OF PAROTID
Bristle inserted.
into duct
Frænum linguæ.
DUCT OF RIVINI-
SUBLINGUAL GLAND
DUCT OF SUBMAXILLARY
GLAND
Mylo-hyoid muscle-
Anterior belly of
digastric muscle
DEEP PORTION OF SUBMAXILLARY GLAND
PAROTID GLAND
Masseter
muscle
Sterno-mastoid
muscle
Posterior belly
of digastric
muscle
LINGUAL
NERVE
SUBMAXILLARY
GLAND, DRAWN
BACKWARDS
Loop of fascia
HYOID BONE
vessels farther back, and contain the sublingual glands Dilatation of the latter
from obliteration of a Rivinian duct, more frequently dilatation of a muciparous
gland-and much more rarely dilatation of Wharton's duct--constitutes a 'ranula."
The submaxillary gland can be felt nearer the angle of the jaw lying between its
fossa and the mucous membrane, especially if pressure is made from outside.
The attachment of the genio-hyo-glossi can be felt behind the symphysis: the
division of it allows the tongue to come well out of the mouth; but when both
have to be divided, the tongue loses much of its steadiness, and may easily fall
back over the larynx during the administration of the anesthetic or, later on, in
sleep. It should therefore be secured forwards for a while with silk. When the
4 C
1122
SURGICAL AND TOPOGRAPHICAL ANATOMY
mouth is widely open, the pterygo-mandibular ligament can be seen and felt beneath
the mucous membrane, behind the last molar tooth. Just below and in front of
the lower attachment of this ligament, the lingual nerve can be felt lying close
to the bone below the last molar. It can be divided here to give relief from pain
in incurable cancer of the tongue, at a point where it crosses a line drawn from
the last molar tooth to the angle of the jaw, by entering a knife nearly three-quarters
of an inch behind and below the tooth, and cutting towards it on the bone (Moore).
Another method is to draw the tongue out of the mouth and expose the nerve
where it lies superficially under the mucous membrane thus made prominent.
(Roser.)
Behind the last molar tooth can be felt the coronoid process, and higher up,
FIG. 669.-SECTION OF THE SKULL AND BRAIN IN THE MEDIAN PLANE. (Braune.)

PITUITARY BODY-
OCCIPITAL BONE
EUSTACHIAN TUBE
Genio-hyo-glossus-
Digastric
Arytenoideus muscle-
RIMA GLOTTIDIS
CESOPHAGUS-
TRACHEA-
THYROID BODY-
Sterno-thyroid muscle-
EPIGLOTTIS
Falx cerebri
Superior longitudinal
sinus
Inferior longitudinal
sinus
CORPUS CALLOSUM
OPTIC CHIASMA
CORPUS MAMMILLARE
Torcular Herophili
POSTERIOR LOBE OF
CEREBRUM
PONS VAROLII
CEREBELLUM
MEDULLA OBLONGATA
-POSTERIOR RING OF ATLAS
-BODY OF AXIS
-BODY OF SECOND THORACIC VERTEBRA
just behind and inside the tooth, the hamular process of the sphenoid. On the
inner side of the coronoid, between it and the tuberosity of the upper jaw, is a
recess where a temporal abscess will point, having travelled down under the fascia
and zygoma. When a patient breathes deeply through the mouth, the soft palate is
raised, the pillars are separated, and the tonsils and the back of the pharynx
are exposed.
TONSILS. The relations of the tonsils should be carefully examined. Thus they
are separated externally by the superior constrictor and pharyngeal aponeurosis
from the ascending pharyngeal and internal carotid arteries. The extent to which
the tonsil is covered by the anterior pillar, how far it projects upwards beneath the
soft palate or downwards into the pharynx, have all important bearings on the
question of removal. Its position corresponds to the angle of the jaw. When
serious hæmorrhage follows operations on the tonsils, it usually comes from one of


THE NOSE
1123
FIG. 670.-SECTION OF THE NOSE, SHOWING THE TURBINAL BONES AND MEATUSES,
WITH THE OPENINGS IN DOTTED OUTLINE.
edi
Frontal sinus
Orifice of middle ethmoidal ce 11s
Orifice of frontal sinus
SUPERIOR TURBINAL BONE
Orifice of the posterior ethmoidal cells
Upper orifice of
nasal duct
Orifice of the sphenoidal sinus
Sphenoidal sinus
கம்
aloold sqads
that of How
Orifice of Eustachian
tube
MIDDLE TURBINAL BONE
Lower orifice of nasal duct
Orifice of infundibulum
INFERIOR TURBINAL BONE Orifice of the antrum
FIG. 671.-SECTION SHOWING BONY AND CARTILAGINOUS SEPTUM.
(The dotted line indicates the course of the anterior palatine canal.)
NASAL BONE
Frontal sinus
UPPER LATERAL CARTILAGE
Groove between septal
and upper lateral
cartilage
caque
bonogo
LOWER LATERAL
CARTILAGE
THICKENED BORDER OF CARTILAGE RESTING
UPON ANTERIOR NASAL SPINE Incisive papilla
ETHMOID
VOMER
Sphenoidal sinus
arina. I
Inoite lo
Pouch at upper extremity
of Stenson's canal
Orifice of Eustachian
tube
SOFT PALATE
SEPTAL CARTILAGE
402
1124
SURGICAL AND TOPOGRAPHICAL ANATOMY
the numerous tonsillar arteries, which is enlarged, and not from the ascending
pharyngeal or internal carotid.
The finger introduced downwards at the back of the mouth, especially if the
parts are rendered insensitive by cocaine, feels the circumvallate papillæ, the
lingual and laryngeal surfaces of the epiglottis, the aryteno-epiglottidean folds, with
the cartilages of Wrisberg and Santorini. If the finger be moved upwards behind
the soft palate and turned upwards to the base of the skull, and then forwards, it
will impinge on the posterior nares, separated by the vomer, and, within each
nostril, the hinder end of the inferior spongy bones; above and behind is felt the
basilar process of the skull.
The size of the nares, one inch by half an inch, and the presence of any adenoids,
are especially to be noted. The richness of the naso-pharynx in glandular structures,
its proneness to inflammation, and of this inflammation to spread to other parts--
e.g. the tympanum-are well known. The finger should be familiar with the feel of
adenoids, or of hypertrophied post-nasal lymphatic nodules-soft bodies of irregular
shape blocking up the naso-pharynx. To make out how far this is the case, it is
well to take the nasal septum as the starting-point.

THE PALATE
Between the diverging pillars of the soft palate is the isthmus faucium,
bounded above by the free margin of the palate, and below by the dorsum of the
tongue. Of its lateral boundaries, the posterior pillars come nearer each other than
the anterior. In paring the edges of a cleft soft palate, the following structures
would be, successively, cut through: (1) Oral mucous membrane; (2) submucous
tissue, with vessels, nerves, and glands; (3) palato-glossus muscle; (4) aponeurosis of
tensor palati; (5) anterior fasciculus of palato-pharyngeus; (6) levator palati and
azygos uvula muscles; (7) posterior fasciculus of palato-pharyngeus; (8) submucous
tissue, vessels, nerves, and glands; (9) posterior mucous membrane. The soft
palate is thicker than it seems, the average in an adult being a quarter of an
inch. The muscles widening a cleft are the tensor and levator, while the superior
constrictor closes it in swallowing. Of the arteries to the palate, the largest is
the descending palatine branch of the internal maxillary. This emerges from
the posterior palatine canal close to the inner side of the last molar tooth, and
runs forward to supply the hard palate..
THE NECK

The
Landmarks in the middle line. Passing from the symphysis to the supra-
clavicular notch is-(1) The body of the hyoid, which is nearly on a level with
the angles of the jaw. On either side of the body are the great cornua.
upper borders of these are the guide to the lingual artery. Below the hyoid is the
thyro-hyoid space, which corresponds with the epiglottis and the upper aperture of
the larynx. Thus, if the throat be cut above the hyoid, the mouth will be opened
and the tongue cut into; if the thyro-hyoid space be cut, the pharynx would be
opened and the epiglottis wounded near its base. Behind the centre of the
anterior margin of the thyroid is the rima glottidis. The projection of the thyroid
notch is much more distinct in men than in women or children. It does not
appear before puberty, and thus flatness of the thyroid must be expected when the
landmarks for tracheotomy are sought for in children with short fat necks. The
cricoid, on the other hand, is always to be made out. It corresponds in horizontal
plane to the following: (1) The fifth cervical vertebra. (2) The junction of

THE NECK
1125
pharynx and œsophagus: from the narrowing of the tube here, foreign bodies may
lodge at this point and cause dyspnoea by pressing on the air-tube in front. The
cricoid is taken as the centre of the incision in oesophagotomy, and also for ligature
of the common carotid. (3) The junction of larynx and trachea. (4) The crossing
of the omo-hyoid over the common carotid. (5) The middle cervical ganglion.
The distance between the cricoid and the manubrium is only about an inch and a
FIG. 672.-THYMUS GLAND IN A CHILD AT BIRTH.

HYOID BONE
Thyro-hyoid
membrane
THYROID CARTILAGE
Thyro-hyoid
muscle
Lateral portion of
crico-thyroid
membrane
Omo-hyoid muscle
Sterno-thyroid!
muscle
Crico-thyroid
membrane
Crico-thyroid.
muscle
THYROID GLAND
Right common
carotid artery
RIGHT PNEUMO-
GASTRIC NERVE
Right internal
jugular vein
Level of sternum
SECTION OF CLAVICLE
SECTION OF FIRST RIB
Sterno-mastoid
muscle
-CRICOID CARTILAGE
-FIRST RING OF TRACHEA
-TRACHEA
Left suspensory
ligament
LEFT RECURRENT
NERVE
Esophagus
Left innominate vein
LEFT LOBE OF THYMUS
Left internal
mammary artery
LEFT LUNG
SECTION OF STERNUM-
Pericardium
SECTION OF FIFTH
COSTAL CARTILAGE
ENSIFORM CARTILAGE
half. When the neck is stretched, about three-quarters of an inch more is gained.
Thus, as a rule, there are not more than seven or eight tracheal rings above the
sternum. Of these, the second, third, and fourth are covered by the thyroid isthmus.
The parts met with in the middle line-(a) above, and (b) below the isthmus-should
be borne in mind:-(a) Thin superficial fascia, branches of transverse cervical and
inframandibular nerves, lymphatics, cutaneous arteries, anterior jugular veins-with
their transverse branches smaller above,-deep fascia, sterno-hyoids, cellular tissue,
superior thyroid vessels, and tracheal layer of deep fascia. The importance of this
1126
SURGICAL AND TOPOGRAPHICAL ANATOMY
last is twofold, as, first, the tube in tracheotomy may be passed between it and the
trachea, and after a wound in this region this layer, continuous with the pericardium,
may conduct discharges into the mediastina. (b) The surface structures are much
the same, but the anterior jugular veins and their transverse branches are much
larger. The inferior thyroid veins are also larger. A thyroidea ima may be
present, and the innominate artery, which often crosses the trachea above the
sterno-clavicular joint, may do so as high as the seventh tracheal ring. The
trachea is also smaller, deeper, and less steadied by muscles. The thymus, too,
in young children may prove a difficulty. Thus, in children, the high operation,
incising the cricoid and crico-tracheal membrane, if needful, is to be preferred.
FIG. 673.-ANTERIOR AND LATERAL CERVICAL MUSCLES.

Stylo-glossus-
Hyo-glossus-
Mylo-hyoid-
Anterior belly
of digastric
Raphe of mylo-
hyoid
Thyro-hyoid
Inferior constrictor-
Anterior belly of omo--
hyoid
Sterno-hyoid-
Sterno-thyroid-
Stylo-hyoid
- Posterior belly of
digastric
Splenius capitis
Sterno-mastoid
Levator anguli scapulæ
Scalenus medius
- Trapezius
Scalenus
posticus
-Posterior belly
of omo-hyoid
The sterno-mastoid is the landmark for several important operations. Its inner
border, the better marked of the two, overlaps the carotids; the common carotid
corresponding, as far as the upper border of the thyroid, with a line drawn from the
sterno-clavicular joint to midway between the mastoid process and the angle of
the jaw. The artery can be best compressed above the level of the cricoid, as
here it is less deeply covered. The transverse process of the sixth cervical vertebra
is called the carotid tubercle, after Chassaignac, who advised compression of the
carotid at this point. This process lies two to three inches above the clavicle.
Compression below it will command the vertebral as well. The student should
recall the deep relations of the sterno-mastoid, which he may classify as vessels
nerves, muscles, glands, bones; or, according to their position, (1) those above the
level of the angle of the jaw; (2) those between the angle of the jaw and the

THE NECK
1127
omo-hyoid; (3) those below the omo-hyoid. The position of the anterior jugular,
curving outwards to pass beneath both origins of the muscle a little above the
clavicle, and the external jugular, crossing at a varying level the outer border of
the clavicular origin, must be remembered in such operations as tenotomy here.
These veins are joined by numerous transverse branches, getting larger below.
Behind the sterno-clavicular joint lie the commencement of the innominate
veins, the bifurcation of the innominate artery on the right, and the common
carotid artery on the left; deeper still lie the pleura and lung. The occasional
FIG. 674.-THE INTERNAL CAROTID ARTERY, AND DEEP BRANCHES OF THE EXTERNAL
CAROTID ARTERY.
(From a dissection in the Hunterian Museum.)
External carotid artery
Temporal artery
Internal maxillary artery
Superior oblique
Transverse facial artery
STENSON'S DUCT
Spienius capitis, cut
Third part of occipital artery
Superior constrictor
Ascending palatine artery
Ascending pharyngeal
artery
External carotid artery,
cut short
Stylo-pharyngeus
Stylo-glossus
Facial artery
LOWER
JAW
Digastricus
Posterior auricular artery
First part of occipital
artery
Princeps cervicis artery
Occipital part of vertebra
artery
Inferior oblique
Complexus
Lingual artery
Semispinalis colli
Complexus
Ascending cervical artery
Deep cervical artery
SUBMAXILLARY GLAND
Superior thyroid artery
Sterno-mastoid, cut
Rectus capitis anticus major
high position of the innominate on the trachea may be a point of importance in
tracheotomy, both at the time of the operation, and later on, from the fatal facility
with which a metal tube, if long retained after a low tracheotomy, may ulcerate
into the vessel.
In front of the sterno-mastoid is the anterior triangle, which is subdivided into
three smaller triangles by the digastric muscle above, and the anterior belly of the
omo-hyoid below. These smaller triangles are called, from above, the submaxillary,
the superior and inferior carotid triangles. The submaxillary or supra-hyoid

1128
SURGICAL AND TOPOGRAPHICAL ANATOMY
FIG. 675. THE COMMON CAROTID, THE EXTERNAL AND INTERNAL CAROTID, AND THE
SUBCLAVIAN ARTERIES OF THE RIGHT SIDE AND THEIR BRANCHES.
(From a dissection by Dr. Alder Smith in the Museum of St. Bartholomew's Hospital.)
Stylo-glossus
INFERIOR DENTAL NERVE
CHORDA TYMPANI
FACIAL NERVE
Internal maxillary artery
Stylo-hyoid, turned up
Digastricus, turned up
Temporal artery
Posterior auricular artery
Internal jugular vein
SECOND CERVICAL NERVE
SPINAL ACCESSORY NERVE
Rectus capitis anticus major-
Stylo-pharyngeus muscle-
SUP. CER. GANGLION OF SYMPATHETIC.
GLOSSO-PHARYNGEAL NERVE-
Sterno-mastoid, reflected
Occipital artery
Internal carotid -
Levator anguli scapulæ
THIRD CERVICAL NERVE
DESCENDENS HYPOGLOSSI
NERVE
External carotid
Inferior constrictor
COMMUNICANTES HYPOGLOSSI
FOURTH CERVICAL NERVE
Ascending cervical artery.
SPINAL ACCESSORY.
PHRENIC NERVE
Scalenus anticus
Levator anguli scapulæ
FIFTH CERVICAL NERVE.
Scalenus medius
CERV. PLEXUS DES. BRANCH
PNEUMOGASTRIC NERVE
BRACHIAL PLEXUS
(SIXTH CERVICAL)
Internal jugular vein.
Superficial cervical artery
Suprascapular artery!
Serratus magnus.
Coraco-brachialis
Submental artery
Facial artery
MYLO-HYOID NERVE
LOWER JAW, TURNED UP
SUBMAXILLARY GANGLION
GUSTATORY NERVE
SUBMAXILLARY DUCT
SUBMAXILLARY GLAND
TONGUE
HYPOGLOSSAL NERVE
Ranine artery
Genio-hyo-glossus
Sublingual artery
-Lingual artery
-Artery of franum
LOWER JAW
Genio-hyoid
Hyo-glossus
Lingual artery
Hyoid branch
Mylo-hyoid muscle
Thyro-hyoid membrane
SUPERIOR LARYNGEAL
NERVE
Superior laryngeal artery
Thyro-hyoid
Superior thyroid artery
Omo-hyoid
EXTERNAL LARYNGEAL
NERVE
THYROID GLAND
Sterno-hyoid
Common carotid
Sterno-thyroid
Vertebral artery
Inferior thyroid artery
Anterior jugular vein
Common carotid
CLAVICLE
Vertebral vein
BRACHIAL PLEXUS
(SEVENTH CERVICAL)
Subclavian artery
Pectoralis major, reflected
Suprascapular artery given off from third
part of subclavian
Posterior scapular artery
SUPRASCAPULAR NERVE
Humeral thoracic artery
Posterior belly of omo-hyoid, drawn down
Transverse cervical artery
Subclavius, reflected
BRACHIAL PLEXUS (EIGHTH CERVICAL)
Pectoral branch of acromial thoracic artery
Subclavian vein
Pectoralis minor
triangle is bounded above by the jaw, and a line drawn back to the mastoid process;
below, by the digastric and stylo-hyoid muscles; and in front by the middle line of
the neck. This space contains the submaxillary gland, and embedded in the gland
are the facial vessels; deeper than the gland are the submental vessels and the

THE NECK
1129
mylo-hyoid vessels and nerve. Posteriorly, and separated from the above structures
by the stylo-mandibular ligament, is the upper part of the external carotid artery
which is embedded in the parotid gland, where it gives off its two terminal and the
posterior auricular branches. More deeply lie the internal jugular vein, internal
carotid artery, and the vagus.
The superior carotid triangle is bounded above by the digastric, below by
the omo-hyoid, and behind by the sterno-mastoid. It contains the upper part of
the common carotid and its branches, the external being somewhat anterior to the
internal. All the branches of the external carotid, save the three just given, are
found in this space, together with their veins, the internal jugular vein, the vagus
and sympathetic nerves, and, for a short distance, the spinal accessory, together
with those nerves which lie in front of and behind the carotids.
The inferior carotid or tracheal triangle is bounded above by the omo-hyoid,
FIG. 676. THE SUBCLAVIAN VESSELS.
(From a dissection in the Hunterian Museum.)
Scalenus medius
Scalenus anticus and
on it the PHRENIC
NERVE
Transverse cervical
artery
Suprascapular artery.
Subclavian artery.
CORD OF BRACHIAL
PLEXUS, GIVING OFF
MUSCULO-CUTANEOUS
AND OUTER HEAD OF
MEDIAN NERVES
Axillary artery
Axillary artery
Thyroid axis
Internal jugular
vein
Right common
carotid artery
VAGUS
Commencement of
innominate vein
MUSCULO-SPIRAL.
NERVE
Subscapular and two circumflex arteries
behind by the sterno-mastoid, and in front by the middle line of the neck. It
contains the lower part of the carotid sheath and its contents, with, behind it, the
inferior laryngeal nerve and inferior thyroid vessels, and to the inner side the
trachea and thyroid gland.
Posterior triangle. This shows in its lower part a wide depression, the supra-
clavicular fossa. Here the brachial plexus may be felt, and, by pressure downwards
and backwards just outside the outer margin of the sterno-mastoid, the pulsation
of the subclavian artery can be stopped against the first rib. This vessel curves
upwards and outwards from behind the sterno-clavicular joint to disappear behind
the centre of the clavicle, the highest point of the curve being half an inch to an
inch above this bone. The subclavian vein lies at a lower level and under cover.
Into the above curve rise the pleura and lung. The transverse cervical artery can
sometimes be felt pulsating a little above the subclavian itself.
1130
SURGICAL AND TOPOGRAPHICAL ANATOMY
Crossing the sterno-mastoid a little obliquely, in a line drawn from the angle of
the jaw to the centre of the clavicle, runs the external jugular vein. About an inch
and a half above the clavicle it perforates the deep cervical fascia, its coats being
blended with the opening. The dilated part between this point and the subclavian
vein is called the sinus, and is marked by two valves, neither of which is usually
perfect. Joining this vein, about the centre of the triangle, is the posterior external
jugular from the occipital region; while just above the clavicle the posterior and
suprascapular, transverse cervical, and a branch from the cephalic, form a plexus
over the third part of the subclavian.
If the posterior border of the sterno-mastoid be traced up, the spinal accessory
nerve, which has entered the muscle about an inch below the tip of the mastoid,
emerges from beneath the posterior border about its centre, and then, continuing
its oblique course across the posterior triangle, disappears on a level with the sixth
FIG. 677.-REGION OF THE THIRD PART OF THE SUBCLAVIAN ARTERY. (Bellamy.)
(The shoulder represented depressed.)

Splenius
Levator anguli scapulæ
Scalenus posticus
A SUPERFICIAL DESCEND-
ING BRANCH OF THE
CERVICAL PLEXUS
BRACHIAL PLEXUS
Transversalis colli artery
(deep)
First serration of
serratus magnus
PHRENIC NERVE
Scalenus anticus
First serration of serratus magnus
Subclavian vein
Suprascapular artery
Subclavian artery
Suprascapular vein
Costo-coracoid membrane and cephalic vein

or seventh cervical spine beneath the trapezius, and descends under this muscle
internal to the vertebral border of the scapula (Godlee). Just above the centre of the
sterno-mastoid, the small occipital, great auricular, and transverse cervical nerves
emerge, the first passing upwards and backwards to the scalp, the second upwards
and forwards across the upper part of the sterno-mastoid to the ear, and the last
turning straight forward to the front of the neck.
Deep cervical fascia.-The arrangement of this must be remembered (a) above,
and (b) below, the hyoid bone. The latter is far the more important.
(a) Arrangement above the hyoid bone.-Here two chief layers, superficial
and deep, can be made out:-(i) The superficial, traced upwards from the hyoid
bone, encloses the submaxillary gland, passing over the mylo-hyoid, and, ascending,
gives off the masseteric and parotid fasciæ, and is attached to the lower border
of the zygoma. (ii) The deeper layer, which forms the stylo-mandibular ligament,

ELOW THE NECK
1131
is important in its power of checking over-action of the external pterygoid. (b) Below
the hyoid bone.-The importance of the fascia here is infinitely greater. Four
FIG. 678.-THE COLLATERAL CIRCULATION AFTER LIGATURE OF THE COMMON CAROTID
AND SUBCLAVIAN ARTERIES.
(A ligature is placed on the common carotid and on the third portion of the
subclavian artery.)
Right anterior cerebral-
Transverse cervical
Posterior scapular
Acromial branch
Subscapular branch
Supraspinous branch
Anterior circumflex
Infraspinous branch
Posterior circumflex
Long thoracic-
Subscapular
Dorsal scapular
Infrascapular-
Subscapular
Occipital-
Princeps cervicis-
Internal carotid-
Right posterior cerebral-
-Left anterior cerebral
Anterior communicating
Posterior communicating
Left posterior cerebral
--Basilar
-Anterior spinal
Vertebral
Facial
Lingual
External carotid-
Superficial branch of--
princeps cervicis
Deep branch
Ascending cervical
Superior thyroid
Deep cervical-
-Inferior thyroid
Superficial cervical-
-Common carotid
Thyroid axis
Superior intercostal
-Innominate
Superior intercostal
-Left common carotid
Left subclavian
-Short thoracic
-Internal mammary
-Anterior intercostal
-First aortic inter-
costal
-Second aortic inter-
costal
-Anterior intercostal
Third aortic inter-
costal
layers must be remembered: (i) Superficial, or subcutaneous; (ii) sterno-clavicular;
(iii) tracheal; (iv) prevertebral. These should first be traced horizontally.
1132
SURGICAL AND TOPOGRAPHICAL ANATOMY
(i) Superficial, or subcutaneous. This starts from the ligamentum nuchæ, encases
the trapezius, forms the roof of the posterior triangle, where it is perforated by
FIG. 679.-DIAGRAM OF THE LAYERS OF THE DEEP CERVICAL FASCIA IN AN ANTERO-
POSTERIOR SECTION OPPOSITE TO THE STERNUM. (Tillaux.)
(The tracheal layer can be seen passing down in front of the longus colli.)

Superficial layer of superficial
fascia
Middle layer
Reduplication of this layer pass-
ing behind the sterno-thyroid,
and enclosing the left innomi-
nate vein, and becoming con-
tinuous with the pericardium
Space occupied by sterno-hyoid
-Left innominate vein
-Innominata
- Pericardium
branches of the superficial cervical nerves and the external jugular vein. Passing
on, it encloses the sterno-mastoid; and, passing over the anterior triangle, it meets
FIG. 680.-DIAGRAM OF THE ARRANGEMENT OF THE DEEP CERVICAL FASCIA, THE
SECTION PASSING THROUGH THE CLAVICLE. (Tillaux.)

HYOID---
Sterno-clavicular layer of deep.-
cervical fascia
Subclavian artery-
Vein-----
Subclavius.
-Superficial layer
Omo-hyoid
CLAVICLE
its fellow in the middle line. Thin behind, it is thickened anteriorly, where it is
united to the next layer. Behind this thickened union lie the anterior jugular veins.

THE NECK
1133
(ii) Sterno-clavicular. This is best marked below. In the middle line it meets its
fellow, and blends with No. i. here also. Passing outwards, it encases the depressors
of the hyoid bone, finally blending with No. i. at the posterior border of the sterno-
mastoid. (iii) Tracheal. This lies under the depressors of the hyoid, over the trachea,
also encasing the thyroid gland. Farther out, it forms the carotid sheath, and,
blending with No. iv. over the anterior scalene, is thus brought into continuity
with Nos. i. and ii. also. (iv) Prevertebral. This layer passes over the longus
colli and rectus capitis anticus major.
The above layers should also be traced vertically, with especial reference to their
relations at the level of the top of the sternum and the clavicle. (a) At the level
of the top of the sternum. (i) Superficial, passes over the sternum. (ii) Sterno-
clavicular: this, descending in front of the depressor muscles, divides just below
FIG. 681.-SECTION OF NECK THROUGH THE SIXTH CERVICAL VERTEBRA. (One-half.)
(Braune.)

RECURRENT LARYNGEAL NERVE
PHARYNX
Longus colli muscle
Superior thyroid artery
DESCENDENS NONI
PHRENIC NERVE
VAGUS
LARYNX
Thyro-arytenoid muscle
CRICOID CARTILAGE
[muscles
Scalenus anticus
Sterno-cleido-
mastoid
BRACHIAL.
-PLEXUS
Scalenus medius.
External jugular vein-
SPINAL
ACCESSORY
NERVE
[thyro- and omo-hyoid
Sterno-hyoid [just posterior are seen the
Crico-arytenoideus lateralis
Muscular process of the thyroid
cartilage
THYROID GLAND
-Common carotid artery
Internal jugular vein
BRACHIAL PLEXUS
-Scalenus medius
-External jugular vein
Scalenus posticus
SPINAL ACCESSORY
NERVE
Levator anguli scapulæ
Splenius
PART OF ARTICULAR SURFACE OF SEVENTH CERVICAL
VERTEBRA
Semi-spinalis and multifid
SIXTH CERVICAL VERTEBRA
Biventer cervicis and complexus
Cervicalis ascendens
Transversalis cervicis and trachelo-
[mastoid
Profunda cervicis vessels
Trapezius
the thyroid cartilage into two layers, which are attached to the front and back of
the sternum. Between these lie some fat and a small gland. (iii) Tracheal: this
passes down over the trachea into the thorax (middle mediastinum). As it
descends, it encases the left innominate vein, and ends by blending with the fibrous
layer of the pericardium. Mr. Hilton suggested that the attachment of this fascia
above, and that of the central tendon of the diaphragm below, to the pericardium
served to keep this sac duly stretched, and so prevented any pressure of the lungs
upon the heart. (iv) Prevertebral: this, descending behind the oesophagus, dips
into the posterior mediastinum. (B) At level of the clavicle. Only two of the above
layers are met with so far outwards as this (i) Subcutaneous, which passes over the
clavicle; (ii) sterno-clavicular, which, having encased the omo-hyoid, passes behind
the clavicle, blends with the sheath of the subclavius, and gives a sheath to the
subclavian vein. That to the artery is derived from No. iii. at the scalenus anticus.
1134
SURGICAL AND TOPOGRAPHICAL ANATOMY
The following uses and important points with regard to the anatomy of the
deep cervical fascia should be noted. (A) It forms certain definitely enclosed
spaces in which pus or growths may form, and by the walls of which these morbid
structures may be tied down and thus rendered difficult of diagnosis, while their
increasing pressure may embarrass the air-passages, etc. Thus: (1) In the first
space, which lies between No. 1 and the skin, the structures met with, platysma
and superficial branches of the cervical plexus, are unimportant. Any abscess
here is prone to extend, but superficially. (2) In the second space, between the
superficial and sterno-clavicular layers, lies a narrow space containing loose cellular
tissue and lymphatic glands. Suppuration here is very common, but usually
comes forwards. (3) This is the largest and most important of all. It is bounded
in front by the sterno-clavicular, and behind by the prevertebral layer. Its contents
are-larynx, trachea, oesophagus, thyroid, carotid sheath, glands; and below, brachial
plexus, subclavian artery, and abundant loose cellular tissue for the movements
of the neck. Suppuration is somewhat rarer here; but either pus or growths, if
confined in this space, may have baleful effects, from pressure, or from their
tendency to travel behind the sternum. (4) This space, between the prevertebral
layer in front and muscles behind, is very limited. Retropharyngeal abscess forms
here, and the dyspnoea it causes is thus explained. (B) The deep cervical fascia gives
sheaths or canals to certain veins which perforate it, e.g. the external jugular. These
are thus kept patent, and a ready passage of blood ensured from the head and neck.
The carotid sheath is another and different instance. (C) It helps to resist atmo-
spheric pressure. (D) Mr. Hilton's suggestion as to its action on the pericardium
has already been mentioned.

SUPERFICIAL ANATOMY OF THE THORAX
Bony points. The top of the sternum corresponds (in inspiration) to the fibro-
cartilage between the second and third thoracic vertebræ, and is distant about two
and a half inches from the spine. If traced downwards, the subcutaneous sternum
presents a ridge opposite to the junction of the manubrium and body, and with the
second costal cartilages on either side. At its lower extremity the xiphoid cartilage
usually retires from the surface, presenting the depression of the scrobiculus cordis,
or pit of the stomach.' This is opposite to the seventh costal cartilages and the
expanded upper end of the recti, and corresponds to the ninth thoracic vertebra
behind.
Sterno-clavicular joint.-The expanded end of the clavicle and the lack of
proportion between this and the sternal facet, on which largely depends the
mobility of this the only joint that ties the upper extremity closely to the trunk,
can be easily made out through the skin. Behind the joint lie, on the right side,
the innominate artery, right innominate vein, and pleura; on the left, the left
innominate vein, the left carotid, and the pleura.
Acromio-clavicular joint.-On tracing the clavicle outwards it is found to rise
somewhat to its articulation with the acromion. This joint has very little mobility,
and owes its protection to the strong conoid and trapezoid ligaments hard by.
Owing to the way in which the joint-surfaces are bevelled, that of the clavicle looks
obliquely downward, and it is an upward displacement of the clavicle which usually
takes place on to the acromion.
Ribs. In counting these, the position of the second is denoted by the transverse

THE THORAX
1135
line at the junction of the manubrium and body of the sternum. The nipple, in
the male, lies between the fourth and fifth, nearly an inch outside their cartilages.
The lower border of the great pectoral corresponds to the fifth rib. The seventh,
the longest of the ribs, is the last to articulate with the sternum. When the arm
is raised, the first three digitations seen of the serratus magnus correspond to the
sixth, seventh, and eighth ribs. The ninth is the most oblique. The eleventh
FIG. 682.-THE ARCH OF THE AORTA, WITH THE PULMONARY ARTERY AND
ada do sobood so CHIEF BRANCHES OF THE AORTA.
(From a dissection in St. Bartholomew's Hospital Museum.)
RIGHT RECURRENT
LARYNGEAL NERVE
Transverse cervical artery
Right common carotid
artery
Suprascapular artery
Internal jugular vein
PNEUMOGASTRIC
NERVE
Subclavian vein
Inferior thyroid vein
PHRENIC NERVE
Left innominate vein
Ascending aortaz
Superior vena cava.
RIGHT BRONCHUS
Branch to superior
lobe of lung
Upper branch of right
pulmonary artery
Branch to middle lobe
of lung
Right pulmonary vein
RIGHT AURICLE.
Right coronary artery.
THORACIC VERTEBRA.
Intercostal vein:
Intercostal artery
Vena azygos major.
Intercostal vein
Intercostal artery.
Intercostal vein,
-THYROID BODY
LEFT RECURRENT
LARYNGEAL
NERVE
PNEUMOGASTRIC
NERVE
Left internal jugular
vein
-Left common carotid
artery
Left subclavian artery
Left subclavian vein
TRACHEA
Inferior thyroid vein
PHRENIC NERVE
(hooked aside)
RECURRENT
LARYNGEAL
NERVE
PNEUMOGASTRIC
NERVE
DUCTUS ARTERIOSUS
Left pulmonary
artery
Pulmonary artery.
Right pulmonary
artery
LEFT BRONCHUS
Left coronary artery
Left pulmonary vein
RIGHT VENTRICLE
(Conus arteriosus)
CESOPHAGUS
(hooked aside)
Intercostal artery.
THORACIC DUCT
Thoracic aorta
and twelfth can be felt outside the erector spinæ. Owing to the obliquity of the
ribs, their sternal ends are on a much lower level than their vertebral extremities.
'Thus the first rib in front corresponds to the fourth rib behind, the second to the
sixth, the third to the seventh, the fourth to the eighth, the fifth to the ninth, the
sixth to the tenth, and the seventh to the eleventh. If a horizontal line be drawn
round the body from before backwards, at the level of the inferior angle of the

1136
SURGICAL AND TOPOGRAPHICAL ANATOMY
scapula, while the arms are at the sides, the line would cut the sternum in front
between the fourth and fifth ribs, the fifth rib at the nipple line, and the ninth rib
at the vertebral column' (Treves). Those most frequently broken are the sixth,
seventh, and eighth. The way in which the ribs are embedded in the soft parts,
and the fact that the fragments are often held in place by the periosteum, accounts
for the difficulty which is often met with in detecting crepitus. The intercostal
spaces are wider in front than behind. The three upper are the widest of all.
Structures passing through the upper aperture of the thorax.-If a horizontal
section is made passing through the manubrium sterni, upper border of the first rib,
and upper part of the first thoracic vertebra, the following structures are met with:-
(1) In the middle line. Sterno-hyoid and sterno-thyroid muscles, with their sheaths
of deep cervical fascia, cellular tissue in which are the remains of the thyroid gland,
the inferior thyroid veins, the trachea and tracheal fascia, the oesophagus and longus
colli muscles. Between the trachea and oesophagus are the recurrent laryngeal
nerves. (2) On each side. The apex of the lung, covered by pleura, rises about
an inch and a half above the first rib. Between it and the trachea and oesophagus
lie the following: the internal mammary artery, the phrenic nerve; on the right
side, the innominate vein and artery, with the vagus between the two, the cardiac
nerves, and the right lymphatic duct. On the left side are the common carotid and
FIG. 683.-SECTION OF THE SIXTH LEFT INTERCOSTAL SPACE, AT THE JUNCTION OF
THE ANTERIOR AND POSTERIOR THIRDS. (Tillaux.)
Intercostal vein.
Intercostal artery.
INTERCOSTAL NERVE
Serratus magnus
Its aponeurosis
Aponeurosis covering external
intercostal muscle
External intercostal muscle
-Aponeurosis covering the internal
intercostal muscle
-Internal intercostal muscle
--PLEURA
subclavian arteries, with the left vagus between them, the cardiac nerves, and the
thoracic duct. Farthest back and on each side are the trunk of the sympathetic, the
superior intercostal artery, and the last thoracic nerve.
The mamma. This lies over the sheath of the pectoralis major, between the
third and fifth, sixth, or seventh ribs in the female. In the male the nipple is
placed in the fourth space, nearly an inch outside the cartilages of the fourth and
fifth ribs. On the nipple itself open the fifteen or twenty ducts which dilate beneath
it, and then diverge and break up for the supply of the lobules. The skin over the
areola is very adherent, pigmented, and fatless. Here also are groups of little
swellings corresponding to some twenty large sebaceous follicles. The skin over
the breast is freely movable, and united to the fascia which encases the organ,
and thus to the interlobular connective tissue, by bands of the same structure-
the ligamenta suspensoria. Under the breast, and giving it its mobility, is a
cellulo-fatty layer, the seat of submammary abscess. The nerves which supply
the breast are the anterior cutaneous branches of the second, third, fourth,
and fifth intercostal nerves, and the lateral branches of the last three. The
connection of these trunks serves to explain the diffusion of the pain often
observed in painful affections of the breast. Thus pain may be referred to
the side of the chest and back (along the above intercostal trunks), over the
scapula, along the inner side of the arm (along the intercosto-humeral nerve, a
THE MAMME
1137
branch of the second intercostal), or up into the neck, probably along the supra-
clavicular branch from the cervical plexus, which communicates with the second
intercostal (Treves). The gland is supplied by the following arteries: the aortic
intercostals of the second, third, fourth, and fifth spaces, similar intercostal
branches from the internal mammary, which run outwards, two small branches
to each space, perforating branches from the same vessel, one or two given off
opposite to each space, the long thoracic and external mammary (when present)
from the axillary. Most of the lymphatics run along the border of the pectoralis
FIG. 684.-ANTERIOR VIEW OF THE LUNGS: PERICARDIUM. (Modified from Bourgery.)

Vena cava superior
BRONCHUS
Pulmonary artery
Pulmonary vein.
LUNC
PLEURA
PERICARDIUM
Arch of aorta
Pulmonary artery
BRONCHUS
Pulmonary vein
A
ENSIFORM CARTILAGE
DIAPHRAGM
major to the axilla; a few pass between the costal cartilages to join the mediastinal
lymphatics.
Structures found in an intercostal space.-(1) Skin; (2) superficial fascia,
with cutaneous vessels and nerves; (3) deep fascia; (4) external intercostal;
(5) cellular interval between intercostals, containing trunks of intercostal vessels
and nerves; (6) internal intercostals; (7) thin layer of fascia; (8) subpleural
connective tissue; (9) pleura (fig. 683).
Parts behind manubrium.-There is little or no lung behind the first bone of the
sternum, the space being occupied by the trachea and large vessels as follows:-
4 D

1138
SURGICAL AND TOPOGRAPHICAL ANATOMY
The left innominate vein crosses behind the sternum just below its upper border.
Next come the great primary branches of the aortic arch. Deeper still is the
trachea, dividing into its two bronchi opposite to the junction of the first and
second bones of the sternum. Deepest of all is the oesophagus. About one inch
from the upper border of the sternum is the highest part of the aortic arch, lying
on the bifurcation of the trachea. (Holden.)
Outline of the lungs. Their relation to the chest-wall. The apex of the lung
rises about an inch and a half (from half an inch to an inch and three-quarters)
above the first rib into the base of the posterior triangle lying behind the inner end
of the clavicle, the sterno-mastoid, and the anterior scalene, covered by the pleura
and deep cervical fascia, and having the subclavian artery arching over it. From
the apices the thin anterior borders converge inwards behind the sterno-clavicular
joints and the first piece of the sternum to the junction of this with the second,
FIG. 685.-OUTLINE OF THE HEART, ITS VALVES, AND THE LUNGS (SHADED). (Holden.)
9
10
8
6
A
3
2
3
7
8
10
almost meeting at this point. Thence the two borders descend parallel and close to
each other (the right sometimes passing just beyond the middle line), and thus
covering over the heart and large vessels, to a point midway between the fourth
pair of costal cartilages, where they diverge, but not to an equal degree. The right
descends in an almost straight line as far as the sixth chondro-sternal joint. The
left is deeply notched (incisura cardiaca). The lower borders of the lung pass down-
wards and outwards across the sides of the chest from the sixth chondro-sternal
joint to the tenth thoracic spine. In the nipple-line the lung reaches the sixth rib,
in the posterior fold of the axilla, the eighth, and opposite the angle of the scapula
(the arms being close to the sides) the tenth rib. Thus, to map out the lung, a line
should be drawn from the apex, a point about an inch and a half above the first
rib, a little outside the sterno-mastoid muscle, obliquely inwards, behind the sterno-
clavicular joint, to near the centre of the junction of the first and second bones of
the sternum. Thence, on each side, a line should be drawn slightly convex as far

RELATIONS OF THE LUNGS TO THE CHEST-WALLS
1139
as a similar point on the sternum lying opposite the articulation of the fourth
chondro-sternal joint. On the right side the line may be dropped as low as the
sixth chondro-sternal joint; on the left (to show the incisura cardiaca) a line should
be drawn sloping outwards from the fourth chondro-sternal articulation along
the lower border of the fourth rib, across the fourth interspace, to a point about an
inch and a half below the left nipple (male) and an inch to its inner side. This
point, lying in the fifth space, marks the apex of the heart. The lower border of
the lung will be marked on the right side by a line drawn from the sixth
chondro-sternal articulation across the side of the chest down to the tenth thoracic
spine. The lower border of the left lung will follow a similar line, starting on a
level with a similar joint (sixth chondro-sternal joint), but much farther out than on
the right side, i.e. in the fifth space, about three inches to the left of the middle
line. This margin of the lung descends about an inch and a half in deep
inspiration, according to Godlee. The position of the great fissure in each lung
may be ascertained approximately by drawing a line from the second thoracic spine
to the sixth rib in the nipple line; and the smaller fissure of the right lung extends
FIG. 686.--DIAGRAM OF THE RELATIONS OF THE THORACIC VISCERA TO THE
WALLS OF THE CHEST. (Bellamy.)

Superior cul-de-sac of right lung-
RIGHT AURICLE-
RIGHT AURICULAR APPENDAGE-
Right auriculo-ventricular-
orifice
Limit of diaphragm in com-.
plete expiration
Limit of the anterior and..
inferior border of right
lung in complete expiration
Limit of right lung in
inspiration
Limit of diaphragm in com-
plete inspiration
Limit of pleura
Superior cul-de-sac of left lung
キキ
​...LEFT AURICLE
Pulmonary orifice
-Left auriculo-ventricular orifice
-Orifice of aorta
Limit of diaphragm in
complete expiration
"Limit of the anterior and infe-
rior border of left lung in
complete expiration
-Limit of left lung in
inspiration
-Limit of pleura
from the middle of the foregoing to the junction of the fourth costal cartilage with
the sternum. It will be seen from the above that there is little lung behind the
manubrium. The connective tissue here between the lung margins contains up to
puberty the thymus, and, later, its remains. The pleura reaches much lower down
than the lung. Thus its lower margin reaches along the seventh rib cartilage near
the sternum; in the axillary line it has reached the lower margin of the ninth rib;
farther back it reaches as low as the twelfth rib, or the eleventh thoracic spine. Thus
it may be opened in operations in the loin, e.g. on the kidney, or in removing the
twelfth rib. Mr. Holden thus draws attention to this lower level of the pleura:
Since the pleura lines the inside of the last rib, a musket-ball or other foreign body,
loose in the pleural sac and rolling on the diaphragm, might fall to the lowest
part of the sac, which would be between the eleventh and twelfth ribs. The ball
might be extracted here. The chest might also be tapped here, but not with a
trocar, since a trocar would penetrate both layers of pleura, and go through the
diaphragm into the abdomen. The operation should be done cautiously by an
incision beginning about two inches from the spine, on the outer border of the
erector spinæ, on a level between the spines of the eleventh and twelfth thoracic
6
4 D 2
1140
SURGICAL AND TOPOGRAPHICAL ANATOMY

vertebræ. The intercostal artery will not be injured if the opening be made
below the middle of the space, which is very wide.'
Outline of the heart. Its relation to the chest-wall. The differences which
exist in various accounts of the limits of the heart may be accounted for by the
fact that its position is not exactly the same in different people, and that the heart's
position may be more or less misplaced by diseases at some distance from it. The
upper limit of the heart (base) will be defined by a line crossing the sternum a
little above the upper border of the third costal cartilage, reaching about half an
inch to the right and about one inch to the left. Its apex corresponds to a point
in the fifth space, about two inches below the male left nipple, and an inch to the
inner side. This point will be about three inches from the left border of the
sternum. The right border (right auricle) will be given by a line, slightly convex
outwards, drawn from the right extremity of the upper border to the right seventh
chondro-sternal joint. If another line, similarly slightly convex, be drawn onwards
from this point across the last piece of the sternum, just above the xiphoid cartilage,
FIG. 687.-ANTERIOR VIEW OF FETAL HEART, VESSELS, AND LUNGS.
SUPERIOR LOBE OF RIGHT LUNG
Aorta
Pulmonary
artery
RIGHT AURICULAR
APPENDIX
MIDDLE LOBE
INFERIOR LOBE
BASE
DUCTUS ARTERIOSUS
Pulmonary
artery
SUPERIOR LOBE OF
LEFT LUNG
LEFT AURICULAR
APPENDIX
Pulmonary
artery
INFERIOR LOBE
Descending aorta
to the apex, it will give the lower border (right ventricle), which rests on the central
tendon of the diaphragm. The left border (left ventricle) will be given by a line,
convex to the left, passing from the left extremity of the upper border to the apex,
well inside the nipple line. This line should be three inches from the middle of
the sternum at the level of the fourth costal cartilage.
If a circle two inches in diameter be described around a point midway between
the left nipple and the lower end of the gladiolus, it will define with sufficient
accuracy for practical purposes that part of the heart which lies immediately
behind the chest wall, and which is uncovered by lung or pleura. (Latham.)
The valves. The pulmonary valves (the most superficial) lie, in front of the
aortic, behind the left chondro-sternal joint, and opposite to the upper border of
the third costal cartilage. The aortic valves lie behind and a little below these,
opposite to the inner end of the third intercostal space, and on a level with the
lower border of the third costal cartilage. The auriculo-ventricular openings
lie at a somewhat lower level than that of the aortic and pulmonary. Thus the
RELATION OF LARGE VESSELS TO THE CHEST-WALLS 1141
tricuspid valves lie behind the sternum at the level of the fourth intercostal
space; and the mitral valves, the most deeply placed of all, lie a little to the left
of these, behind the left edge of the sternum and the fourth left costal cartilage.
Thus these valves are so situated that the mouth of an ordinary-sized stetho-
scope will cover a portion of them all, if placed over the juncture of the third inter-
costal space, on the left side, with the sternum. All are covered by a thin layer of
lung; therefore we hear their action better when the breathing is for a moment
suspended.' (Holden.)
The reader will remember that abnormal murmurs resulting from a diseased
condition of these valves do not correspond with their exact anatomical position.
Thus aortic murmurs are best heard at the second right costal or aortic' cartilage;
mitral murmurs at the apex beat; tricuspid ones near the ensiform cartilage.
Relation of vessels to the wall of the thorax.-Aortic arch. The ascending
part reaches from a spot behind the sternum, a little to the left of the centre, on a
level with the third left costal cartilage, to the upper border of the second right
cartilage; thus it passes upwards, backwards, and to the right, and is about two inches
long. The transverse part then crosses to the left behind the sternum (the highest
part of the arch being about an inch below the notch), reaching from the second
right costal cartilage to the lower border of the fourth thoracic vertebra on the left
side. This part recedes from the surface, and, with the next, cannot be marked out
on the surface. The third, or descending part, the shortest of the three, reaches
from the lower border of the fourth to that of the fifth thoracic vertebra.
Innominate artery.-A line drawn from the top of the arch, about an inch
below the sternal notch, and a little to the right of the centre, to the right sterno-
clavicular joint, will give the line of this vessel.
Left common carotid. This vessel will be denoted by a line somewhat similar
to the above, passing from the level of the arch a little to the left of the last
starting point to the left sterno-clavicular joint.
Left subclavian artery. A line from the end of the transverse arch, behind
the left of the sternum, straight upwards to the clavicle, delineates the vertical
thoracic course of the long left subclavian artery. (Sheild.)
Innominate veins.-The left, three inches long, extends very obliquely from
the left sterno-clavicular joint, to a point half an inch to the right of the sternum,
in the first intercostal space. The right, about an inch long, descends almost
vertically to the above point from the right sterno-clavicular joint.
Vena cava. The superior descends from the point above given for the meeting
of the innominate veins in the first intercostal space, close to the sternum, and
perforates the right auricle on a level with the third costal cartilage. The inferior
vena cava. The opening of this vein into the right auricle lies under the middle
of the fifth right interspace and the adjacent part of the sternum.
Internal mammary artery. This descends behind the clavicle, the costal
cartilages, and the first six spaces, about half an inch from the edge of the sternum.
In the sixth intercostal space it divides into musculo-phrenic and superior epigastric
arteries.


THE ABDOMEN

Skin markings; bones and muscular landmarks.-The linea alba, or meeting
of the aponeuroses of the great abdominal muscles over, under, and between the
recti, reaches from the apex of the xiphoid cartilage to the symphysis. It is best
marked above the umbilicus. Its little vascularity and comparative thinness fit
this line for the point of election for operations on the abdominal cavity. In the

11428 SURGICAL AND TOPOGRAPHICAL ANATOMY
linea alba, a little below its centre, is the umbilicus.
This corresponds to the level
of the fibro-cartilage between the third and fourth lumbar vertebræ, the tip of the
third lumbar spine (Windle), the highest point of the iliac crests, and a point
three-quarters of an inch to one inch above the bifurcation of the aorta.
On each side of the linea alba, and about two and a half to three inches from
it (according to the muscular development), a line, curved with a slight convexity
outwards, the linea semilunaris, denotes the point of division of the abdominal
aponeuroses, reaching from the ninth costal cartilage to the pubic spine. Between
the linea alba and the linea semilunaris run the three lineæ transversæ, of which
one is placed at the umbilicus, another at the xiphoid cartilage, and a third between
the two, on a level with the tenth costal cartilage. There is, rarely, a fourth below
the umbilicus.
In very corpulent subjects two deep transverse furrows run across the abdomen.
One runs across the navel and completely conceals it. The other is lower down, just
FIG. 688.-OBLIQUUS EXTERNUS AND FASCIA LATA.
Obliquus
internus
Aponeurosis
of obliquus
externus
SPERMATIC
CORD
Origin of
cremaster
Triangular.
fascia
Insertion of
cremaster
Loops of
cremaster
Obliquus
externus
-Inter-
columnar
fibres
-Poupart's
ligament
-External
abdominal
ring
-Saphenous
opening
above the fat of the pubes. In tapping the bladder above the pubes in such a case,
the trocar should be introduced where this line intersects the linea alba. (Holden.)
A transverse line drawn from one anterior superior spine to the other is about
the level of the promontory of the sacrum. Such a line will always show whether
the pelvis is horizontal or not. (Holden.)
Poupart's ligament corresponds to a line drawn with a slight curve downwards
between the anterior superior spine and the pubic spine. The first of these bony
prominences corresponds to the starting point of the above ligament, the attachment
of the fascia lata to the ilium, the meeting of the fleshy and aponeurotic parts of
the external oblique (denoted by a line drawn upwards from this spine to the ninth
costal cartilage, or often a little anteriorly to these points), the point of emergence of
the external cutaneous nerve, and part of the origins of the internal oblique, transver-
salis, and tensor vaginæ femoris. The pubic spine marks the outer pillar of the
external abdominal ring, the mouth of which corresponds to the crest, or that part

THE ABDOMINAL RINGS
1143
of the pubes lying between the spine and the symphysis. The ring, and especially
its outer pillar, can easily be felt by invaginating the scrotal skin with a finger, and
FIG. 689.-THE PECTORALIS MINOR, OBLIQUUS INTERNUS, PYRAMIDALIS, AND
RECTUS ABDOMINIS.

Levator anguli scapulæ
Biceps
Pectoralis
major
Teres major
Subscapularis
Pectoralis minor
Latissimus dorsi
Serratus magnus
Internal oblique
Rectus
Pyramidalis
Conjoined tendon
1144
SURGICAL AND TOPOGRAPHICAL ANATOMY
pushing upwards and outwards. In a female patient, if the thigh be abducted, the
tense tendon of the adductor magnus will lead up to the site of the ring. The
internal ring is situated about half an inch above the centre of Poupart's ligament;
oval in shape, and nearly vertical in direction, it has the arching fibres of the transver-
salis above it, and to its inner side the deep epigastric artery. The canal runs
obliquely downwards and forwards between the two rings. In the adult it is about
an inch and a half long, but in early life, and in adults with a large hernia dragging
upon the parts, the two rings are much nearer, and may be one behind the other.
If the external ring be exposed, and the finger thrust carefully up the canal,
the following structures will be noted:-After the finger has carefully dilated the
canal, its tip will be prevented from entering the abdomen by the infundibuliform
fascia. If it be pressed downwards it will feel Poupart's ligament, which, with
the meeting of the fascia transversalis, forms the floor; above, it will be arrested
by the arching fibres of the internal oblique and transversalis, coming down to the
pectineal line to form the conjoined tendon. Towards the abdominal wall the finger
will feel the aponeurosis of the external oblique stretching over the whole anterior
aspect of the canal; if turned towards the belly cavity, the finger would feel less
resistant layers, viz. extra-peritoneal fat and peritoneum, and, behind the external
ring, the conjoined tendon. The finger would of course also take notice of the
spermatic cord in the male and the round ligament in the female, and investigate
any thickening of the former, and isolate the vas deferens.
Vessels in the abdominal wall. The three superficial branches of the common
femoral, the external pudic (superior and inferior), epigastric and circumflex iliac,
supply the lower part of the abdominal wall and the adjacent groin and genitals.
The only others that have to be remembered are the deep epigastrics and epigastric
branch of the internal mammary, the deep circumflex iliacs, the last two inter-
costals, and the abdominal branches of the lumbar arteries. Of these, the deep
epigastric is the most important; its course will be marked out by a line drawn.
from a point just internal to the centre of Poupart's ligament, upwards and
inwards to the inner side of the internal ring, and thence to a point about midway
between the pubes and umbilicus. Here the vessel, which at first lies between the
peritoneum and fascia transversalis, perforates the latter and, passing over the fold
of Douglas, enters the sheath of the rectus. It then runs upwards, closely applied
to the back of that muscle, and a little above the level of the umbilicus divides
into branches which anastomose with the epigastric or abdominal branch of the
internal mammary.
Lymphatics. It is sufficiently correct to say here that those above the umbilical
line go to the axillary, and those below that line to the femoral glands.
Nerves. The lower seven intercostals and the ilio-hypogastric and ilio-inguinal
supply the abdominal wall. The sixth and seventh intercostals supply the skin over
'the pit of the stomach'; the eighth the area of the middle linea transversa; the tenth
that of the umbilicus; the last thoracic, ilio-inguinal and ilio-hypogastric, the region
above Poupart's ligament, and that of the pubes. The ilio-hypogastric supplies
the skin over the external ring; the ilio-inguinal that over the cord and scrotum.
The last thoracic and ilio-hypogastric cross the iliac crest to supply the skin of the
buttock.
Viscera and visceral regions.-The general form of the abdominal space, and
the relations of the several organs before they are disturbed from their normal
positions, are given on pages 994 and 995. The arbitrary regions into which the
abdomen is usually divided are described at the end of this article.
The diaphragm.-The upper limit of the abdomen rises to the following levels:
Its central tendon to about the lower end of the sternum, or the seventh chondro-
sternal joint; the right half to about the level of the fifth rib, or about one inch
below the nipple; the left half not rising quite so high.

RELATION OF VISCERA TO THE ABDOMINAL WALLS 1145
Viscera behind the linea alba. From above downwards there are the following
(fig. 690):-(1) Above the umbilicus-the left lobe of the liver, the stomach,
the transverse colon, part of the great omentum, the pancreas and solar plexus.
(2) Below the umbilicus-the rest of the great omentum, covering in the small
intestines and their mesentery. In the child, the bladder occupies a partly
abdominal position; and in the adult, the same viscus, if distended, may rise out
of the pelvis and displace the above structures, raising the peritoneum until, if
distended half way to the umbilicus, there is an area of nearly two inches safe
for operations above the symphysis. The gravid uterus also rises along the
linea alba.
FIG. 690.-THE VISCERA AS SEEN ON FULLY OPENING THE ABDOMEN WITHOUT
DISARRANGEMENT OF THE INTERNAL PARTS. (After Sarazin.)

LIVER-
Falciform-
ligament
of liver
TRANSVERSE-
COLON
CÆCUM-
BLADDER
DIAPHRAGM
GREAT OMENTUM
SMALL
INTESTINE
SIGMOID
FLEXURE
The liver. In the erect position, the anterior thin edge of the liver projects about
half an inch below the costal cartilages, but can only be made out with difficulty
in this position. It may be also displaced downwards by pleuritic effusion or tight
lacing. The liver is also, proportionately, much larger in little children.
Of the three parts of the liver (according to the regions which it occupies), that
in the right hypochondrium corresponds to the lower margin of the thorax; but in
the epigastric region the anterior margin, running obliquely across from the ninth
right to the eighth left costal cartilage, crosses the middle line about a hand's
breadth below the sterno-xiphoid articulation (Godlee). The size of the left lobe
varies. In infants it will occupy the left hypochondrium; in adults its extent to the
left will vary from a point an inch and a half or two inches beyond the sternum to the

1146
SURGICAL AND TOPOGRAPHICAL ANATOMY
left nipple line. The level of the upper border varies also with position, respiration,
etc. It may be represented, on the right, by a line drawn about one inch below the
nipple, along the seventh rib, towards the middle line, the fifth chondro-sternal
joint, and the sterno-xiphoid articulation (or central tendon of the diaphragm);
on the left side it does not reach quite so high: thus its level would be marked
by the sixth chondro-sternal joint. Behind, the liver would be below the base
of the right lung, on a level with the tenth thoracic spine (figs. 718, 719, and
720).
Gall-bladder. The fundus of this, situated in a fossa on the under surface of
the right lobe of the liver, and having the quadrate lobe to its left, lies opposite
to the right ninth costal cartilage, close to the outer edge of the rectus. It is in
contact with the hepatic flexure of the colon and the first piece of the duodenum.
Stomach. This organ varies in position more than any other, owing to its
mobility, save at the cardiac orifice, and to its varying distension. When empty and
FIG. 691.-SECTION OF ABDOMEN BETWEEN THE THIRD AND FOURTH LUMBAR
VERTEBRE. (Braune.)
UMBILICUS
Rectus
GREAT OMENTUM
SYMPATHETIC
URETER
Transversalis
TRANSVERSE COLON
Internal oblique
DESCENDING COLON
Quadratus lumborum
Quadratus
Psoas
Aorta
ARTICULAR PROCESS OF THIRD LUMBAR
Psoas
Vena cava
INTERVERTEBRAL CARTILAGE
External oblique
ASCENDING COLON
contracted, it lies far back in the abdomen, under the left lobe of the liver, and in
front of the pancreas. When much distended, its pyloric end moves to the right,
and the organ comes forwards, pushing against the liver and abdominal wall; and
upwards, against the diaphragm, and thus against the heart and left lung. If
moderately distended, the cardia will be found under the seventh left chondro-
sternal joint, about one inch beyond the sternum. The pylorus is very mobile, but
a spot near the end of the cartilage of the eighth rib will denote it with sufficient
accuracy. It is on a deeper plane than the cardia. By joining these two points
with lines representing the lesser and greater curvatures, the stomach can be
marked out (figs. 718, 719). The usual inaccuracies committed in delineating
the stomach are as follows: The viscus is marked too horizontally-students
forget its oblique position. The greater curvature and fundus are not marked high
enough on the left side. They are placed high up under the left arch of the
diaphragm, well to the left of the middle line, as high as the sixth chondro-sternal
joint. The lesser curvature is usually made too curved and too horizontal. (Sheild.)

RELATION OF VISCERA TO THE ABDOMINAL WALLS 1147
The pancreas. This lies a little obliquely behind the stomach, crossing the
aorta, inferior cava, and spine about the junction of the first and second lumbar
vertebræ, or three inches above the umbilicus (fig. 587, page 1024, and fig. 720,
page 1178). A little lower is the third piece of the duodenum, reaching to within
an inch of the umbilicus. (Godlee.)
Intestines (A) Small.-The only part of these that can be localised at all
definitely is the duodenum and its junction with the jejunum and the ending of
the ileum in the cæcum. The first piece of the duodenum lies in the right hypo-
chondrium, usually near the gall-bladder (vide supra), reaching from the pylorus
upwards, backwards, and to the right. This is the most mobile of the three parts,
The second, or descending, is in relation with the head of the pancreas, and
reaches the right lumbar region, descending as low as the second or third lumbar
vertebra. The third, or oblique, portion passes from the third lumbar vertebra
obliquely from right to left across the second, and, ascending, ends in the jejunum
on the left side of the spine. This portion of the intestine being firmly secured
FIG. 692.-DIAGRAM SHOWING RELATION OF KIDNEY TO CAPSULE.

TRANSVERSE COLON
DESCENDING COLON
PERITONEUM
FATTY CAPSULE
CUT EDGE OF
PERITONEUM
Muscular fibre in
subperitoneal
tissue
PANCREAS
Sup. mesenteric vein
DUODENUM
Vena cava
KIDNEY
PERITONEAL CAVITY
Diaphragmatic
fascia
Parietal muscles/
Subperitoneal tissue Fatty capsule Renal vessels embedded in subperitoneal tissue
LYMPHATIC GLAND
LUMBAR VERTEBRA
in place by fibres from the left crus of the diaphragm and the commencement
of the mesentery, accounts for rupture of the intestine usually occurring near this
spot. The jejunum and ileum lie below the line of the transverse colon, covered
by the omentum, the jejunum being above and the ileum below.
(B) Large intestine.-The cæcum with its appendix, the ileo-cæcal valve and
termination of the ileum, occupy the right iliac fossa. The valve is in a line drawn
horizontally inwards from the anterior superior line for about three inches from
that point (Sheild). The ascending colon, covered by small intestine, lies deeply as it
passes up over the kidney through the right lumbar region. The hepatic and splenic
flexures lie deeply also in the hypochondriac regions, the splenic being much
higher than the hepatic, and behind the stomach, while the former is in contact with
the under surface of the liver. Between the two courses the transverse colon, in
close contact with the great curvature of the stomach, and varying in position from
one, two, or three inches above the umbilicus, to one nearer or even below this point.
The descending colon follows a similar course to the ascending; and the sigmoid
1148
SURGICAL AND TOPOGRAPHICAL ANATOMY
flexure occupies the left iliac fossa, and from this point passes over the brim of the
pelvis. Except at its hepatic and splenic flexures, the colon can be examined through
the parietes, aided by an anæsthetic. The cæcum is the most superficial of all.
Landmarks for lumbar colotomy.-(1) The lower border and tip of the last rib,
which varies in length; (2) a point half an inch behind the centre of the iliac
crest, this point being found by accurate measurement along the crest between the
anterior and posterior spines (Allingham); (3) a line drawn vertically upwards
from the last-mentioned point to the last rib. This gives with sufficient correct-
ness the line of the outer edge of the quadratus, and the position of a normal
colon.
The kidneys. These lie so deeply in the hypochondriac, lumbar, epigastric, and
umbilical regions as to be beyond palpation, unless enlarged. They lie much higher
than is usually supposed, the upper part being well covered by the ribs. The right
is slightly lower than the left. They lie deep in the loins, along the sides of the last
thoracic and first three lumbar vertebræ. The upper edge corresponds with the space
between the eleventh and twelfth ribs, and the lower edge is nearly on a level with
FIG.693.-TRANSVERSE SECTION OF THE ABDOMEN THROUGH THE KIDNEYS AND
PANCREAS, AT THE LEVEL OF THE FIRST LUMBAR VERTEBRA. (Braune.)
Inferior cava

Round ligament
Rectus
EIGHTH RIB
STOMACH
SIGMOID FLEXURE
DESCENDING COLON
External oblique.
PANCREAS-
SPLEEN
KIDNEY
Splenic vein
Descending aorta
BODY OF FIRST LUMBAR VERTEBRA
TRANSVERSE COLON
Psoas
SEVENTH RIB
ASCENDING COLON
DUODENUM
EIGHTH RIB
Obliquus externus
NINTH RIB
PLEURA
TENTH RIB
LIVER
Diaphragm
ELEVENTH RIB
TWELFTH RIB
the middle of the third lumbar spine. They occupy a space which is represented on
the anterior surface of the body by the following surface markings. A horizontal
line through the umbilicus is below the lower edge of each kidney; a vertical line
carried upwards to the costal arch from the middle of Poupart's ligament has one-
third of the kidney to its outer side, and two-thirds to its inner side, i.e. between
this line and the median line of the body. On the posterior surface of the body
the kidney's boundaries are indicated by the following:-(1) A line parallel with,
and one inch from, the spine, between the lower edge of the tip of the spinous
process of the eleventh thoracic and the lower edge of the spinous process of the third
lumbar vertebra; (2) and (3) lines drawn from the top and bottom of this line
outwards, at right angles to it, for two inches and three-quarters; (4) a line parallel
to the first, and connecting (2) and (3). Within this parallelogram the kidney lies.
(Morris.)
The spleen. This lies very obliquely from above downwards, and from within
outwards, in the left hypochondrium: thus its long axis corresponds closely with
the line of the tenth rib. It is placed opposite the ninth, tenth, and eleventh ribs


RELATIONS OF THE SPLEEN
1149
externally, being separated from these by the diaphragm; and internally it is con-
nected with the great end of the stomach. Below, it overlaps slightly the outer
border of the left kidney (figs. 694, 719, 720, 721, and 722). Its highest point is on
a level with the spine of the ninth thoracic, and its lowest with that of the eleventh
thoracic vertebra. Its inner end is distant about an inch and a half from the median
plane of the body, and its outer about reaches the mid-axillary line (Godlee). In
the natural condition it cannot be felt; but if enlarged, its notched anterior margin
extends downwards towards the umbilicus, and is both characteristic and readily felt.
FIG. 694.-THE ABDOMINAL AORTA AND INFERIOR VENA CAVA.
LEFT LOBE OF LIVER
GALL BLADDER
HEPATIC DUCT
CYSTIC DUCT
COMMON DUCT
Portal vein
Gastro-duodenal br.
Superior pyloric
Hepatic artery
Right suprarenal vein
Inferior suprarenal
artery
Renal artery.
Renal vein
Inferior vena cava
KIDNEY
CESOPHAGUS
Left phrenic artery
Right phrenic artery
Superior suprarenal
Gastric artery
Inferior suprarenal
Splenic artery
Left phrenic vein
Left suprarenal vein
Superior mesenteric
artery
CO
KIDNEY
Ureteric branch
of renal
Left spermatic vein
Right spermatic vein
Right spermatic
artery
Quadratus lumborum
muscle
Lumbar artery and
vein
Ureteric branch of
spermatic artery
Middle sacral vessels
URETER
Left spermatic artery
-Inferior mesenteric
artery
Ureteric branch of
spermatic
Ureteric branch of
common iliac
Common iliac artery
External iliac artery
Internal iliac artery
Aorta and iliac arteries. The aorta enters the abdomen opposite the last
thoracic vertebra (a point five to six inches above the umbilicus), and thence, lying to
the left of the spine, divides into the two common iliacs opposite the disc between
the third and fourth lumbar vertebræ, or opposite the body of the fourth lumbar
vertebra. This point is about one inch below and to the left of the umbilicus, and
on a level with a line drawn across the highest part of the iliac crest. A line drawn
from this point, with a curve slightly outwards, to just within the centre of
Poupart's ligament will give the line of the iliac arteries; the first two inches (about)
giving the average length of the common iliac.
1150
SURGICAL AND TOPOGRAPHICAL ANATOMY
The site of some of the branches of the aorta may be thus approximately
remembered.
The cœliac axis is given off immediately after the aorta has perforated the
diaphragm; directly below this is the superior mesenteric artery. About one inch
lower down, or three inches above the umbilicus, the renal arteries are given off.
About one inch above the umbilicus would be the level of the inferior mesenteric
artery.

THE PERINEUM AND GENITALS
Bony boundaries. These are the same in either sex. Above and in front is
the symphysis pubis, rounded off by the subpubic ligament; diverging downwards
and outwards from this point on either side are the rami of the pubes and ischium,
ending at the tuberosities of the latter. In the middle line behind is the apex of
FIG. 647. THE MALE PERINEUM. (Modified from Hirschfeld and Leveillé.)
BULBO-CAVERNOSUS
Superficial triangular ligament
ISCHIO-CAVERNOSUS
Muscles of thigh
INFERIOR PUDENDAL NERVE
SUPERFICIAL PERINEAL NERVE
INFERIOR HÆMORRHOIDAL NERVE
CUTANEOUS BRANCH OF FOURTH SACRAL
Gluteus maximus
TUBEROSITY OF ISCHIUM
Great sacro-sciatic ligament
Levator ani
Sphincter ani
Superficial transversus perinæi
the coccyx; and reaching from this to the tuberosities are the great sacro-sciatic
ligaments, to be felt by deep pressure, with the lower border of the gluteus
maximus overlapping them.
In the middle line, extending longitudinally through the perinæum, is the raphe,
THE MALE PERINEUM
1151
the guide to the urethra, and the line of safety' (on account of the small size of
the vessels here) for operations on it.
An imaginary line drawn transversely across the perinæum from one tuber ischii
to its fellow divides the lozenge-shaped space into two triangles-(1) An anterior,
or urethral; and (2) a posterior, or rectal.
The central point of the perinæum is in the adult nearly an inch in front of
the anus, or midway between the centre of the anus and root of the scrotum. Here
the following structures meet, viz. the sphincter ani, the two transverse perinæal
muscles, the accelerator urinæ, and the levator ani. It also corresponds to the
centre of the lower margin or base of the triangular ligament. Its development
varies much in different bodies. A little in front of this point is the bulb, with the
FIG. 696.-MALE PERINEUM. (Roser.)
The bulb is slightly raised and the rectum drawn backwards, in order to make clear the
membranous urethra and prostate, which are shown incised as in the lateral operation of
lithotomy.

BULB
Erector penis
Wilson's muscle
URETHRA DIVIDED AS IN
THE LATERAL INCISION
Artery to bulb(abnormal)
PROSTATE GLAND, WITH ITS
PLEXUS OF VESSELS
Superficial perincal
artery
Levator ani, its
anterior fibres raised
to show the prostate
Gluteus maximus
Continuation of internal
pudic artery
Anterior layer of
triangular ligament
-Artery to bulb
--COWPER'S GLAND
INCISION IN THE PROSTATE
GLAND AS IN THE LATERAL
OPERATION
-Transversus perinæi
muscle
Trunk of internal pudic
---RECTUM
External sphincter
corpus spongiosum passing forwards from it. This would also be the level of the
artery of the bulb, so that in lithotomy the incision should always begin below
this point. A knife introduced at the central point, and carried backwards and
very slightly upwards, should enter the membranous urethra just in front of the
prostate. If pushed more deeply it would enter the neck of the bladder. In lateral
lithotomy the knife is entered an inch and a half in front of the anus and carried
downwards and outwards for two and a half or three inches into the ischio-
rectal fossa, ending a little below and external to the mid-point between the anus
and tuber ischii. This incision begins deeply and ends more superficially. In
the deeper part of the incision the knife is carried along the staff through the
membranous urethra into the bladder. The parts divided in the operation are skin,
superficial fascia (both layers), transverse perinæal vessels and nerves, superficial
perinæal vessels and nerves, inferior hæmorrhoidal vessels and nerves, transversus

1152
SURGICAL AND TOPOGRAPHICAL ANATOMY
perinæi muscle, base of triangular ligament (anterior layer), membranous urethra
and deep muscles, a venous plexus, posterior layer of triangular ligament, prostatic
urethra, and left lobe of prostate and its capsule in part, with some of the fibres
of the levator prostatæ. In median lithotomy, an incision an inch and a half
long is made through the central tendinous point and raphe, so as to hit the
membranous urethra. The following structures are divided:-Skin and fasciæ;
some of the most anterior fibres of the sphincter ani; raphe and central tendinous
point; minute branches of transverse perinæal vessels and nerves; base of triangular
ligament in centre; membranous urethra and compressor urethræ.
The urethra. This can be examined in part with the finger, but much better with
the aid of a sound. The anterior, or penile, part is movable; the posterior, or deeper,
FIG. 697. THE ARTERIES OF THE PERINEUM.
On the right side Colles's fascia has been turned back to show the superficial vessels. On the
left side the superficial vessels have been cut away with the anterior layer of the triangular
ligament to show the deep vessels.
Superficial perineal-
vessels
Accelerator urinæ-
Crus penis
Dorsal artery of penis
Artery of crus
Colles's fascia, turned-
back
Erector penis-
Transverse perineal vessels-
Cut edge of triangular-
ligament
SUPERFICIAL
PERINEAL NERVE
Pudic vessels
Transverse perineal vessels-
and nerve
EA
BULB
-Artery of bulb
-COWPER'S GLAND
-Fudic artery
Great sciatic ligament
Levator ani
-External sphincter
-Gluteus maximus
Gluteus maximus,
hooked back
more fixed. It is narrowest at the meatus and where the membranous urethra
passes through the triangular ligament. It is widest in the prostatic part and the
fossa navicularis. One of the most important landmarks is the triangular ligament,
the base of which can be just felt in a thin perinæum. The membranous urethra
passes through this, about three-quarters of an inch above the central point of the
perinæum, and about the same distance below the subpubic ligament. Above the
urethra run the dorsal vessels and nerves of the penis. The fixation, undilatability,
surrounding muscular fibres, and close neighbourhood of a large amount of erectile
tissue (the bulb), all account for difficulties in introducing instruments past this
point. It is here also that the urethra is most liable to be damaged by a fall or
blow. The attachment of the deep layer of superficial fascia to the base of the
triangular ligament accounts for the fact that urine extravasated from a ruptured
ALA THE URETHRA
1153
urethra, or through an opening behind a stricture, passes usually not backwards
into the anal triangle, but forwards into the scrotum and abdominal wall.
FIG. 698.-SAGITTAL SECTION OF MALE PELVIS IN THE MESIAL LINE. (One-third.)
(Braune.)

BLADDER
SYMPHYSIS PUBIS
BULB
POUCH OF DOUGLAS
RECTUM
VESICULA SEMINALIS
DUCTUS EJACULATORIUS
PROSTATE
External sphincter
Internal sphincter
External sphincter
Ischio-rectal fossa. Most of the boundaries of this space (page 1102) can be
made out with the finger in a thin subject. The loose, poorly vitalised fat which
FIG. 699.-SECTION SHOWING THE ISCHIO-RECTAL FOSSA IN ITS RELATIONS TO
THE PELVIC VISCERA.

OS PUBIS
Muscles---
Levator ani with recto-vesical,
and ischio-rectal fasciæ
Obturator internus
Internal pudic vessels and
NERVES in obturator fascia-
TUBER ISCHII-
Ischio-rectal fossa with its
anterior and posterior ex-
tensions
Gluteus maximus
300
SYMPHYSIS PUBIS
Pubo-prostatic ligaments00300
Prostatic plexus
PROSTATE
Capsule of prostate formed
by recto-vesical fascia
Fat
RECTUM INVESTED BY RECTO-
VESICAL FASCIA
occupies it, the dependent position of the part, its terminal blood-supply, its exposure
to cold and damp, and the close vicinity of decomposing fæces, all account for the
frequency
of abscess here. The position of the pudic vessels and nerve in their
4 E

1154
SURGICAL AND TOPOGRAPHICAL ANATOMY
FIG. 700.-SCHEME OF THE PUDIC ARTERY AND ITS BRANCHES.
Subpubic ligament with aperture for
dorsal vein of the penis
Apertures for dorsal artery and nerve,
of the penis
Dorsal vein of penis
CRUS PENIS
Aperture for artery of corpus
cavernosum
Superficial triangular ligament
Ischio-cavernosus
Aperture for artery.
to bulb
Urethral aperture
Aperture for Cow-
per's duct
Position of bulb
Apertures for super--
ficial perinæal ves-
sels and nerve
DORSAL NERVE
Anterior layer of triangular
ligament
Dorsal artery of penis
Deep triangular
ligament
Artery of corpus
cavernosum
Artery to bulb
Pudic veins
DORSAL NERVE
POSITION OF COWPER'S
GLAND
Internal pudic artery
Fascia of Colles,
turned backwards
Posterior border
of perinæal ledge
(junction of trian-
gular ligaments
with fascia
Colles)
FIG. 701.-THE MUSCLES ATTACHED TO THE PUBES. (From a dissection in the
of
Pectineus
Adductor longus.
Hunterian Museum.)
External oblique-
Rectus abdominis
CORPORA CAVERNOSA-
Adductor brevis.
Below it and exter-
nally are adductor
magnus and obtur-
ator externus
CORPUS SPONGIOSUM
Accelerator urinæ-
Raphe.
Quadratus femoris
Semi-tendinosus and
biceps below. (The
line has by mistake
been drawn beyond
the semi-tendinosus
to point to the
lowest fibres of the
adductor magnus.)
Transversus perinæi
Central tendinous point
Sphincter ani
Rectus abdominis
Pectineus
Adductor longus
Adductor brevis
Obturator externus
Adductor magnus
Gracilis
Erector penis
Transversus perinæi
FEMALE EXTERNAL GENITALS
1157
(4) the vaginal orifice with the hymen or its remains; (5) the fossa navicularis ;
(6) the fourchette; (7) the skin over the base of the perinæal body.
These parts have been described elsewhere, and only those points which are of
importance in a clinical examination will be alluded to here.
The labia majora are two thick folds of skin, covered with hair on their outer
surface, especially above where they unite (anterior commissure) in the mons
Veneris. They contain fat, vessels, and dartos, but become rapidly thinner below,
where they are continuous with the fourchette in front of the perinæum (their
posterior commissure).
When the above folds are drawn aside, the labia minora, or nymphæ, appear,
not projecting in a healthy adult beyond the labia majora. They are small folds
of skin, which meet above in the prepuce of the clitoris, and below blend with
the labia majora about their centre.
The glans clitoridis, covered by its prepuce, occupies the middle line above.
FIG. 704.-DIAGRAMMATIC REPRESENTATION OF THE PERINEAL STRUCTURES
ISCHIO-PUBIC ARCH-
CRUS CLITORIDIS WITH-
ISCHIO-CAVERNOSUS
BULBO-CAVERNOSUS-
COVERING BULBUS
VESTIBULI
Superficial trian-
gular ligament
IN THE FEMALE.

GLANS CLITORIDIS
WITH PREPUCE
PARS
INTERMEDIALIS
Mucous mem-
brane of
vestibule
MEATUS URINARIUS
BULBUS VESTIBULI
GLAND OF
BARTHOLIN
-Sphincter ani

Below it comes the vestibule, a triangular smooth surface of mucous membrane,
bounded above by the clitoris, below by the upper margin of the vaginal orifice, and
laterally by the labia minora. In the middle line of the vestibule and towards
its inner part, about half an inch below the glans clitoridis, and an inch above the
fourchette, is the meatus or opening of the urethra (figs. 703, 704).
The vaginal orifice lies in the middle line between the base of the vestibule
above, and the fossa navicularis below. Its orifice is partially closed in the virgin
by a fold of mucous membrane, the hymen (fig. 703). This is usually crescentic in
shape, attached below to the posterior margin of the vaginal orifice, and with a free
edge towards the base of the vestibule. In some cases it is diaphragmatic, i.e.
attached all round, but perforated in the centre (fig. 703).
The shrivelled remains of the hymen probably constitute the carunculæ
myrtiformes. On either side of the vaginal orifice, at its lower part, lie the
racemose, muciparous glands of Bartholin, situated beneath the superficial perinæal

1158
SURGICAL AND TOPOGRAPHICAL ANATOMY
fascia and sphincter vaginæ. Their ducts run slightly upwards and open, external
to the attachment of the hymen, within the labia minora.
Fourchette and fossa navicularis.-This, as stated above, is the lower com-
missure of the labia majora. Normally the inner aspect of this is in contact with
the lower surface of the hymen. When the fourchette is pulled down by the finger,
a shallow depression is seen, the fossa navicularis, with the fourchette for its
posterior, and the hymen for its anterior boundary.
Examination per vaginam.-The finger, introduced past the gluteal cleft,
perinæum, and fourchette, comes upon the elliptical orifice of the vagina, and notes
FIG. 705.-SECTION OF THE FEMALE PELVIS. (After Henle.)
SYMPHYSIS
PERITONEUM
VESICAL WALL
CAVITY OF
BLADDER
PREVESICAL FAT
Dorsal vein-
CLITORIS
Deep trans-
versus perinæi
LABIUM MAJUS
Unstriped muscular fibre
URETHRA
•...
ANUS
Internal sphincter ani
Part of external sphincter ani
LABIUM MINUS
Unstriped muscular fibre
Vessels
VAGINAL ORIFICE
UTERUS
RECTUM
COCCYX
Recto-coccy-
geal muscle
POSTERIOR LIP
OF OS UTERI
ANTERIOR LIP
-VAGINA
External
sphincter ani
Internal
sphincter ani
how far it is patulous or narrow; the presence or otherwise of any spasm from the
adjacent muscles; then, passing into the canal itself, the presence or absence of
rugæ, a naturally moist, or a dry condition are observed. In the anterior wall the
cord-like track of the urethra can be detected; and further up than this, if a sound
be passed, the posterior wall of the bladder. The anterior wall of the vagina is two
to two and a half inches long. The posterior wall, three inches long, forms the
recto-vaginal septum, and through it any fæces present in the bowel are easily felt.
The cervix uteri is next felt for in the roof of the vagina, projecting downwards and
PARTS CONCERNED IN INGUINAL HERNIA
1159

backwards in a line drawn from the umbilicus to the coccyx. Besides its direction,
its size, shape, mobility, and consistence should be noted. The os uteri should form
a dimple or fissure in the centre of the cervix. Of its two lips the posterior is the
thicker and more fleshy-feeling of the two. The vaginal culs-de-sac or fornices are
next explored. These should be soft and elastic, giving an impression to the finger
similar to that when it is introduced into the angles of the mouth. Any resistance
felt here may be due to scars, swellings connected with the uterus (displacements, or
myomata), effusions of blood or inflammatory material, and, in the case of the lateral
culs-de-sac, a displaced or enlarged ovary, or dilatations of the Fallopian tubes.
HERNIA
PARTS CONCERNED IN INGUINAL HERNIA
In inguinal hernia, as in femoral and umbilical, there is a weak spot in the
abdominal wall-one weakened for the needful passage of the testicle from inside
to without the abdomen. The parts immediately concerned are the two abdominal
rings, external and internal, and the canal. Now it must be remembered at the
outset that the rings and canal are only potential-they do not exist as rings
or canal save when opened up by a hernia, or when so made by the scalpel. The
canal is merely an oblique slit or flat-sided passage. The external and internal
rings are so intimately blended with the structures that pass through them, and
so filled by them, that they are potential rings only.
EXTERNAL RING.-This is usually described as a ring: it is really only a separa-
tion or gap in the aponeurosis of the external oblique, by which in the male the
testicle and cord, and in the female the round ligament by which the uterus is
kept tilted a little forwards, pass out from the abdomen. The size of this opening,
the development and strength of its sides or pillars, the fascia closing the ring-all
vary extremely. Formation: by divergence of two fasciculi of the external oblique
aponeurosis. Boundaries: two pillars-(1) Internal, the smaller, attached to the
symphysis and blending with the suspensory ligament of the penis; (2) external,
stronger, attached to the pubic spine and blending with Poupart's ligament, and so
with the fascia lata. On this outer, stronger pillar rests the cord (and so the weight
of the testicle), or round ligament. Shape: triangular or elliptical, with the base
downwards and inwards towards the pubic spine.
Intercolumnar fascia. External spermatic fascia.-This, derived from the
lower part of the aponeurosis of the external oblique, ties the two pillars together,
and, being continued over the cord, prevents there being any ring here, unless
made with a scalpel. This is the rule in the body: when any structure passes
through an opening in a fibrous or muscular layer, it carries with it a coating
of tissue from that layer; e.g. the inferior cava passing through the foramen
quadratum in the diaphragm, and the membranous urethra through the triangular
ligament.
Effect of position of the thigh on the ring.-As the lower pillar is blended with
Poupart's ligament, and as the fascia lata is connected with this, movements of
the thigh will affect the ring much, making it tighter or looser. Thus extension
and abduction of the thigh stretch the pillars and close the ring. In flexion and
adduction of the thigh the pillars are relaxed; and this is the position in which
reduction of a hernia is attempted. In flexion and abduction of the thigh, the ring

1160
SURGICAL AND TOPOGRAPHICAL ANATOMY
is open; and this is the position in which a patient should sit, to try on a truss, and
cough. If the hernia is now kept up, the truss is satisfactory.
Helping to protect this most important spot, and preventing its being more than
a potential ring, are not only the two pillars, and the intercolumnar fascia, but also a
structure which has been called a third or posterior pillar, namely, the triangular
fascia. This has its base above at the lower part of the linea alba, where it joins its
fellow and the aponeurosis of the external oblique, and its apex downwards and out-
wards, where, having passed behind the internal pillar, it blends with Gimbernat's
ligament. Again, the conjoined tendon of the internal oblique and transversalis
curving inwards and downwards to be attached to the ilio-pectineal line and spine
FIG. 706.--THE PARTS CONCERNED IN INGUINAL HERNIA.
(From a dissection in the Hunterian Museum.)
External oblique, cut and turned back

Internal oblique
External oblique
odi te
Conjoined
tendon
ddgiew
osed ad
Poupart's ligament
Triangular ligament
Transver
salis
-Fascia
transver-
salis
-PERITONEUM
Common
femoral
vessels
is a most powerful protection, behind, to what is otherwise a weak spot and a
potential ring.
INGUINAL CANAL.-This is not a canal in the usual sense, but a chink or flat-
sided passage in the thickness of the abdominal wall. The descriptions of the
canal usually given apply rather to the diseased than to the healthy state. It was
a canal once, and for a time only, i.e. in the later months of fœtal life. It remains
weak for a long time after, but only a vestige of it remains in the well-made adult.
On the inner surface of the abdomen we have a few inconspicuous inguinal
fossettes; on the outer surface a separation between the fasciculi of the external
oblique, carefully closed and protected; in the interval between the two surfaces
lies the cord or round ligament, in the thickness of the abdominal wall.
Length. In very early life there is no canal; one ring lies directly behind the


INGUINAL HERNIA
1161
other, so as to facilitate the easy passage of the testis. In the adult it measures
about an inch and a half in length, this lengthening being brought about by the
growth and separation of the alæ of the pelvis. This increased obliquity gives
additional safety.
Direction. From internal to external ring, downwards, forwards, and in-
wards.
Boundaries. For convenience sake, certain limits (largely artificial) have been
named-
(1) Floor. This is best marked near the outlet, where the cord rests on the
grooved upper margin of Poupart's ligament. The meeting of the transversalis
fascia with this ligament forms the floor.
(2) Roof. The apposition of the muscles and the arched border of the internal
oblique and transversalis.
(3) Anterior wall.-Skin, superficial fascia, external oblique for all the way.
Internal oblique, i.e. that part arising from Poupart's ligament, for the outer third
or so.
(4) Posterior wall.--For the whole extent, transversalis fascia, extra-peritoneal
tissue, and peritoneum. For the inner two-thirds, conjoined tendon of internal
oblique and transversalis, and the outer edge of the triangular fascia, when
developed. Of the structures forming the posterior wall the transversalis fascia is
the strongest. It is thicker and better marked at its attachments below; these
are (a) externally, to inner lip of iliac crest; (b) to Poupart's ligament between
the anterior superior spine and the femoral vessels: here it joins the fascia iliaca
(c) opposite the femoral vessels it also joins the fascia iliaca, and forms with it a
tubular sheath; (d) internal to the femoral vessels the fascia transversalis is attached
to the ilio-pectineal line, behind the conjoined tendon, with which it blends.

6
;
INTERNAL RING.-It has already been said that the term 'ring' is here mis-
applied except in an artificial sense, as when an opening is made by a scalpel; or
in a pathological one, as when a hernia is making its way by opening up the parts.
The terms internal and external' are also misapplied as far as their usual
application to the middle line of the body is concerned. The terms apply to depth
only. The internal ring' is not a ring in the least, but merely a funnel-shaped
expansion of the transversalis fascia, which the cord carries on with it as it escapes
from the abdomen. This expansion may be weakened, but it is never an opening
save when made so artificially.
Site.-Midway between the anterior superior spine and spine of pubes. Shape:
oval, with the long diameter upwards. Dimensions: one inch by half an inch.
Both these are artificial. Boundaries: centre of Poupart's ligament, about half an
inch below. Internally the deep epigastric artery, and thus the inner side seems
to be better defined. But the outer side is really the better defined, as here
the transversalis fascia is descending to Poupart's ligament, to form the deep
'crural' arch, and to help to close in the great gap or notch between Poupart's
ligament and the innominate bone. Owing to the artery lying to the inner side,
the incision, in cutting to relieve the deep constriction of an inguinal hernia,
should always be made directly upwards, so as to avoid the above vessel.
Coverings. There are two chief forms of inguinal hernia :-
A. The common form: external, or oblique. External, because it appears
(at the internal ring) external to the deep epigastric artery. Oblique, because it
traverses the whole of the inguinal canal, entering it at its inlet and leaving it at
its outlet.
B. Rarer form: internal, or direct. Internal, because it appears internal to
the deep epigastric artery. Direct, because, instead of making its way down the
whole oblique canal, it comes by a short cut, as it were, only into the lower part
of the canal, and then emerges by the same opening as the other.


1162
SURGICAL AND TOPOGRAPHICAL ANATOMY
A. Oblique, external inguinal hernia. This obtains its coverings as
follows:-
(1) At the internal ring, or inlet, it obtains three: (a) Peritoneum;
(b) extra-peritoneal fat; (c) infundibuliform fascia, or the layer of transversalis
fascia prolonged at this spot along the cord.
(2) In the canal it obtains one. As it emerges beneath the lower border of the
internal oblique, it gets some fibres from the cremaster.
(3) At the external ring, or outlet, the hernia obtains three, viz.: (a) Inter-
columnar fascia; (b) superficial fascia; and (c) skin.
B. Direct or internal inguinal hernia. This does not come through the
internal ring, but, making its way through the posterior wall of the lower third
of the canal-i.e. the conjoined tendon, either pushing this forward or splitting it-
gets its coverings only from structures in relation to this part of the canal. They
(1) Peritoneum; (2) extra-peritoneal fat; (3) transversalis fascia (not the
are
FIG. 707.-DISSECTION OF THE LOWER PART OF THE ABDOMINAL WALL FROM WITHIN,
THE PERITONEUM HAVING BEEN REMOVED. (Wood.)
Fascia trans-
versalis
Epigastric artery-
Internal abdo-
minal ring
VAS DEFERENS
Spermatic
vessels
Border of the
posterior part
of the sheath
of the rectus
(fold of Doug-
las)
Posterior sur-
face of rectus
Conjoined
ten-
don in the
triangle
Hesselbach
of
Obliterated hypo-
gastric artery
Lymphatics
in
crural rings
External iliac artery
specialised part at the internal ring or infundibuliform fascia); (4) conjoined
tendon of internal oblique and transversalis. At the outlet of the external ring the
coverings obtained are the same as in the oblique hernia, viz. (5) intercolumnar
fascia; (6) superficial fascia; (7) skin.
Hitherto the two forms of inguinal hernia have been considered from the super-
ficial aspect, that in which they are met with in practice. The inguinal region
should also be studied as to the posterior aspect of its so-called rings and canal,
as these have to bear the early stress of a commencing hernia. It is against this
aspect that a piece of omentum or intestine is constantly and insidiously pressing,
and endeavouring to make its way out. Furthermore, when either of the above
constituents of hernia have made their way a little farther, and got out into the
internal ring or into the canal, the patient is no longer sound.
INGUINAL HERNIA
1163
On the posterior wall are certain cords and depressions, marking off regions
which correspond to those on the surface.
Thus, there are three prominent cords, and three fossæ.
Three cords (1) Median, or urachus; (2) lateral, or the obliterated hypogastric
arteries.
(1) Median, or urachus. This interesting foetal relic, the intra-abdominal part
of the allantois, passes up between the apex of the bladder and the umbilicus, and
by so doing-(a) keeps the bladder up, especially in early life, when the pelvic cavity
is but little developed; (b) it keeps the bladder well up so that it shall be above the
level of the urethra, and so more easily emptied; (c) it provides, by thus keeping
up the bladder, that it shall enlarge in a direction which will admit of the greatest
amount of distension, i.e. one between the lower or yielding part of the abdominal
wall and the hollow of the rectum, which is compressible.
(2) The obliterated hypogastric arteries. These, the remains of vessels which
during foetal life carry the impure blood of the foetus out to the mother through
FIG. 708.-VERTICAL SECTION OF PELVIS PASSING THROUGH THE HEADS OF THE
THIGH BONES. (Blandin.)

Deep epigastric vessels
INNER BORDER OF INGUINAL CANAL
Internal abdominal ring
External iliac vein.
ILIUM
VAS DEFERENS
CRURAL CANAL
Pelvic fascia.
Obturator fascia
Levator ani
Recto-vesical fascia
RECTUM
ISCHIO-RECTAL FOSSA
Fascia iliaca
Obliterated hypogastric
artery
BLADDER
INTERNAL PUDIC VESSELS AND
NERVE

the umbilicus, run up and join the urachus at the umbilicus. In relation to these
cords are the following fossæ: (a) An internal one, between the urachus and
the obliterated hypogastric artery. This corresponds, on the anterior surface, to
the external abdominal ring. Through this fossa comes direct inguinal hernia.
(b) Between the obliterated hypogastric artery and the deep epigastric artery,
running upwards and inwards to form the outer boundary of Hesselbach's
triangle, is a middle fossa. This is the smallest of all. (c) The external fossa
is outside the deep epigastric artery. It is the most distinct of the three from
the way in which the cord or round ligament passes down within a glove-like
process of the transversalis fascia. This fossa corresponds to the internal ring.
Causes of hernia. It will be well, while the anatomy of hernia is being con-
sidered, to refer briefly to the causes, as many of these are intimately bound up
with the anatomy of the parts. Amongst the chief are the following:-
(1) Hereditary, viz. weakness of abdominal wall; openness of rings.
(2) Weak spots. (a) The presence of the cord; (b) deficiency of some of the
1164
SURGICAL AND TOPOGRAPHICAL ANATOMY
layers below; (c) persistence of the original process of peritoneum; (d) a long
mesentery or suspensory ligament of the intestines. Mr. Lockwood has shown
that the mesentery is relatively larger in infancy, and that there is a rapid decrease
after the second year. In adults its length is about eight inches, and any
lengthening of the mesentery beyond this point is likely to be combined with a
protuberant belly. He shows further, with regard to the range of descent or
the excursus of the intestines, that it is extremely rare to find a mesentery so short,
or attached so high, as to prevent the intestines escaping or being drawn from the
abdomen.
The long mesentery of infancy and childhood is usually associated with con-
FIG. 709.-TRANSVERSALIS ABDOMINIS AND SHEATH OF RECTUS.

External intercostal
Internal intercostal-
Posterior portion of-
sheath of rectus
Transversalis
abdominis
Fold of Douglas
Iliacus
Transversalis fascia and
internal abdominal ring
Conjoined tendon
Poupart's ligament
Gimbernat's ligament"
-Serratus magnus
Lumbar fascia
siderable downward descent of the intestine; and in the adult it is quite common
to find that the small intestines will pass an inch and a half beyond the right
crural arch, one inch beyond the pubes, and up to the left crural arch.
(3) Stretching of the abdominal walls by pregnancies, etc.
(4) Increase of the volume and weight of the parts within: e.g. omentum by
deposit of fat in it.
(5) Sex. Thus, men have larger inguinal rings. Women have a larger
femoral arch, and one less well filled in by muscles, and with less strong fascia
meeting, e.g. iliac and transversalis.
(6) Cough, asthma, bronchitis, habitual fretfulness or crying.

FEMORAL HERNIA
1165
(7) Straining to expel urine, as with phimosis, stricture, stone in bladder, etc.
(8) Straining in defæcation.
(9) Lifting heavy weights.
(10) Results of wounds or abscesses which have weakened the abdominal wall.
(11) Whatever diminishes the abdominal cavity, e.g. tight-lacing.
FEMORAL HERNIA
As many of the parts concerned here are also met with in inguinal hernia, one
description, given now, will suffice.
With regard to descriptions of the inguinal and femoral regions, it is always
well to bear in mind the following: (1) That the so-called rings and canals are
merely weak spots in the inguinal and femoral regions, and that they do not exist
FIG. 710.-SUPERFICIAL DISSECTION OF THE INGUINAL AND FEMORAL REGIONS. (Wood.).

Superficial epigastric
artery
Inguinal lymphatic
glands
Intercolumnar fascia
External abdominal
ring
Saphenous opening
Superior external
pudic artery
ILIO-INGUINAL
NERVE
Internal saphena vein
Femoral lymphatic
glands
Poupart's ligament
Intercolumnar fibres
of external oblique
Superficial circumflex
iliac artery
Deeper layer of
fascia (reflected), the
superficial vessels
being left attached to
the external oblique
Superficial layer of
fascia (reflected)
distinctly, and do not get beyond the potential stage, unless made by a scalpel or
a hernia; (2) that at the fold of the groin most of the layers blend together, and
that descriptions of them as separate layers, for convenience sake in learning
them, is more or less artificial; (3) that the description of these layers has been
most needlessly complicated by the number of terms used, many of which are
simply substitutes for others; (4) many of these terms are not only useless but
incorrect, e.g. saphenous, crural, etc.
Parts concerned in femoral hernia. (1) Skin and superficial fascia of
groin. The latter consists of two layers: (a) Superficial layer of superficial
fascia. Fatty, met with over the whole groin, and continuous with the superficial
fascia of the rest of the body. (b) Deep layer of superficial fascia.-Thin and
membranous, only met with over the lower third of the abdominal wall and to
1166
SURGICAL AND TOPOGRAPHICAL ANATOMY
the inner side of the groin. It is continuous through the scrotum with the deep
layer of the superficial fascia of the perinæum. Just below Poupart's ligament it is
joined to the fascia lata. From these last two facts it results that in rupture or
giving way of the urethra the extravasated urine may come forwards by way of
the genitals, and from the continuity of the fascia make its way on to the abdomen,
but not down on to the thigh.
Between the two layers of superficial fascia lie the superficial glands of the groin,
the superficial branches of the common femoral artery, one or two cutaneous nerves
and some veins descending to the saphenous opening to join the long saphena vein.
(2) Poupart's ligament. This is also known as the crural arch, a misnomer,
as 'crus' means leg. A description of its shape and attachments is given on
page 1144. Owing to the connection of the fascia lata to its lower border, the
'saphenous opening,' which is situated in the fascia lata, and has its upper cornu
blending with Poupart's ligament, will be affected by movements of the thigh,
much as is the external abdominal ring, being tightened and stretched when the
limb is extended and abducted, relaxed when it is adducted and flexed.
The parts beneath it which block up the gap between it and the innominate
bone are of the utmost importance in preventing the escape of a femoral hernia.
(3) Gimbernat's ligament. This is merely the triangular internal attachment
of Poupart's ligament. Its apex is attached to the pubic spine; of its three borders
the base is free towards the vein and the femoral canal. Its upper border is
continuous with Poupart's ligament, its lower is attached to the ilio-pectineal line.
(4) Fascia lata.-Two portions are described over the upper part of the thigh:-
(a) An iliac, external and stronger, attached to Poupart's ligament in its whole
extent and lying over the sartorius, ilio-psoas, and rectus. (b) A pubic, internal,
weaker, and much less well defined, is attached above to the ilio-pectineal line and
the spine of the pubes. The upper cornu of the saphenous opening' is at Gim-
bernat's ligament, and at the lower cornu the two portions of the fascia blend.
Their relation to the femoral vessels.-The iliac portion, being attached along
Poupart's ligament, passes over these. The pubic portion, fastened down over the
pectineus, which slopes down on to a deeper plane than the adjacent muscles,
passes behind the femoral vessels to end on the capsule of the hip joint.
(5) Saphenous opening. This is doubly a misnomer. It is not an opening, but
an oval depression, situated at the spot where the two parts of the fascia lata diverge
on different levels. As without dissection it is not an opening but an oval depression,
fossa ovalis would have been a better term were it not otherwise employed. Though
the fascia lata is wanting here, there is no real opening, as the deficiency is made
up by the deep layer of superficial fascia, or cribriform fascia, which fills up the
opening. The term saphenous' is also misapplied: etymologically it means very
evident.' Now it is notorious that in very many subjects this opening only becomes
plain when rendered an artificial one by dissection; and that thus, with the limited
opportunities of one or two subjects, it is by no means easy to verify the details
about it which have been described as constant.
6
Uses of the saphenous opening. Though a weak spot, it is so on purpose to
transmit the saphena to the femoral vein, and the superficial to the deep lymphatics.
The depression is present in order to allow the saphena vein to be protected
from pressure in flexion of the thigh.
Site. At the inner and upper part of the thigh, with its centre an inch and
a half below and outside the spine of the pubes.
Diameters.-One inch vertically, by a half or three-quarters of an inch. Shape:
oval, with its long axis downwards and outwards. Two extremities or cornua: upper
blending with Gimbernat's ligament; lower, where the two parts of the fascia lata
meet. Two borders: outer also known as the ligament of Hey, or femoral ligament,
or falciform process of Burns. Semilunar in shape, arching downwards and outwards

FEMORAL HERNIA
1167
from Gimbernat's ligament to the inferior cornu. This lies over the femoral vessels,
and is adherent to them; to it is fixed superficially the cribriform fascia (vide infra).
The inner border is much less prominent, owing to the weakness of the pubic part
of the fascia lata which forms it.
(6) Femoral sheath. This is a funnel-shaped sheath, carried out by the femoral
vessels under Poupart's ligament, and continuous above (in front) with the trans-
versalis fascia as it descends to the ligament, lining the inner surface of the
abdominal wall, and (behind) with the iliac fascia, and below continuous with the
proper sheath of the femoral vessels.
It is not only funnel-shaped, but large and loose, for two reasons: (a) That there
be plenty of room for the femoral vein, and the slowly moving venous current in it
to ascend without compression; (b) to allow of all the movements of the thigh
taking place-flexion and extension-without undue stretching of the vessels. By
two connective tissue septa the sheath is divided into three compartments--the
outer for the artery, the middle for the vein, and the internal one for the femoral
canal (vide infra). Thus one septum lies between the artery and vein, and
another between the vein and the femoral canal (fig. 711).

FIG. 711.-SECTION THROUGH THE CRURAL ARCH AND SHEATH OF THE
FEMORAL VESSELS. (Blandin.)
Septum between femoral
vein and gland
FEMORAL CANAL
Posterior layer of
sheath of vessels
Poupart's ligament
Anterior layer of sheath
of vessels (transver-
salis fascia)
ANTERIOR CRURAL
NERVE
External portion of
sheath of vessels
(7) Femoral canal.-Definition: the innermost division of the femoral sheath.
The fascia transversalis and fascia iliaca meet directly on the outer side of the femoral
Hence a space
artery, but not so closely on the inner side of the femoral vein.
exists here, perhaps to prevent the thin-walled vein, with its sluggish current, being
pressed upon. Thus a slight gap exists here-not a canal, unless so made by a
knife or by the dilating influence of a hernia. Length: about three-quarters
of an inch. Limits: below, saphenous opening; above, femoral ring (vide infra).
Boundaries.-Externally, septum between it and vein; internally, base of
Gimbernat's ligament and meeting of fascia iliaca and transversalis; behind,
fascia iliaca; in front, fascia transversalis.
Contents. Cellular tissue and fat, continuous with extra-peritoneal fatty layer.
Lymphatic gland, which is inconstant. Lymphatics passing from superficial (groin)
glands to those deep in the iliac fossa.
(8) Femoral ring. This is mainly an artificial product. It is the upper or
abdominal opening of the femoral canal. Shape: oval, with its long axis trans-
verse. It is larger in women. Boundaries: internally, Gimbernat's ligament;
externally, the femoral vein; in front, Poupart's ligament and the thickening of
the transversalis fascia attached to it, and called the deep crural arch;' behind,

1168
SURGICAL AND TOPOGRAPHICAL ANATOMY
the pectineus and the ilio-pectineal line. It is closed by the septum crurale, which
is a barrier of fatty connective tissue, continuous with the extra-peritoneal fatty
layer, perforated by lymphatics passing from the superficial to the deep group.
Position of vessels around the ring. Outside, the femoral vein; above, the
epigastric vessels; towards inner side there may be an unimportant branch
between the epigastric artery above and the obturator below.
If, instead of the above unimportant branch, the obturator artery comes off
abnormally from the deep epigastric, it will descend, and usually does so, close to the
junction of the external iliac and common femoral vein, and thus to the outer, and
FIG. 712.-IRREGULARITIES OF THE OBTURATOR ARTERY. (After Gray.)
A

Deep circumflex iliac artery
External iliac artery
External iliac vein-
Obturator foramen-
-Internal ring with spermatic
vessels cut short in it
-Deep epigastric artery
Lymphatic gland in femoral
ring
The obturator artery, given off
from the external iliac with the
deep epigastric, descends to gain
the obturator foramen, but at a
safe distance from the femoral
ring

B
The obturator artery, coming off
from the deep epigastric, takes
a course so near to the femoral
ring that it would very likely
be divided by the bistoury intro-
duced from without to divide
the base of Gimbernat's liga-
ment, the cause of the constric-
tion
so the safe, side of the ring (fig. 712, A). In a very few cases it curves more inwards,
close to Gimbernat's ligament, and thus to the inner side of the ring, and is then
in great danger (fig. 712, B). Sir William Lawrence calculated that this took place
once in a hundred cases.
Course of femoral hernia. At first this is downwards in the femoral canal.
A pouch of peritoneum having been gradually, after repeated straining, coughing,
etc., pushed through the weak spot, the femoral ring, further weakened perhaps,
together with all the parts in the femoral arch, by child-bearing, some extra effort
will force intestine or omentum into this pouch and thus form a hernia. Thus

FEMORAL HERNIA
1169
U2
formed, femoral hernia passes at first downwards in the femoral canal as far as the
saphenous opening, but, as a rule, does not go farther downwards on the thigh, but
mounts forwards and upwards, and somewhat outwards, even reaching the level
of Poupart's ligament. The reasons for this change of position are (1) The
narrowing of the femoral sheath, funnel-like, i.e. wide above but narrowed below;
(2) the unyielding nature of the lower margin of the saphenous opening; (3) the
fact that this margin and the outer border are united to the femoral sheath;
(4) the constant flexion of the thigh; (5) the fact that vessels (chiefly veins) and
lymphatics descend to the saphenous opening, the veins to join the saphena vein,
and the lymphatics to join the deeper group: these descending vessels serve to
loop upwards or suspend a femoral hernia, and thus prevent its further course
downwards.
Coverings of a femoral hernia. (A) At the upper or femoral ring it obtains
peritoneum, extra-peritoneal fat, and septum crurale.
(B) In the canal, a coating of the femoral sheath.
(C) At the external or superficial opening, further coverings of cribriform fascia,
skin, and superficial fascia are added.
Some of these may be deficient by the hernia bursting through them, or they may
be matted together. Sir A. Cooper thought this especially likely to occur with the
layer of femoral sheath and septum crurale to which he gave the name of fascia
propria.



PARTS CONCERNED IN UMBILICAL HERNIA
A hernial protrusion at the umbilicus, or exomphalos, may occur at three
distinct periods of life, according to the anatomy of the part. Any account of
umbilical hernia would be incomplete without an attempt to explain how this region,
originally a most distinct opening, is gradually closed and changed into a knotty
mass of scar, the strongest point in the abdominal wall.
During the first weeks of fœtal life, in addition to the urachus, umbilical arteries,
and vein, some of the membranes and a portion of the intestine pass through the
opening to join that part of the digestive tract which is developed outside the
abdomen up to a certain time, and then re-enters that cavity. Occasionally this
condition persists, owing to failure of development, and the child is born with a
large hernial swelling outside the abdomen, imperfectly covered with skin and
peritoneum. To this condition the term congenital umbilical hernia should be
applied.
Later on in fœtal life it is the umbilical vessels alone which pass through this
opening. At birth there is a distinct ring which can be felt for some time after in the
flaccid walls of an infant's belly. If this condition persist, a piece of intestine may
find its way through, forming the condition which should be known as infantile
umbilical hernia.
This condition is not uncommon. Why it is not more frequently met with is
explained by the way in which this ring of infancy is closed and gradually con-
verted into the dense mass of scar tissue so familiar in adult life. This is brought
about (1) by changes in the ring itself; (2) by changes in the vessels which pass
through it.
(1) Changes in the ring itself.-The umbilical ring is surrounded by a sphincter-
like arrangement of elastic fibres, best seen during the first few days of foetal life,
on the posterior wall of the belly. In older infants these fibres lose their elasticity,
become more tendinous, and then shrink more and more. As they contract they
divide, as by a ligature, the vessels passing through the ring, thus accounting for the
fact that the cord, wherever divided, drops off at the same spot and without bleeding.
(2) Changes in the vessels themselves. When blood ceases to traverse these,

4 F

1170
SURGICAL AND TOPOGRAPHICAL ANATOMY
their lumen contains clots, their muscular tissue wastes, while the connective tissue
of their outer coat hypertrophies and thickens. Thus the umbilical vessels and the
umbilical ring are, alike, converted into scar-tissue, which blends together. This
remains weak for some time, and may be distended by a hernia (infantile).
Finally, we have to consider the state of the umbilicus in adult life. The very
dense, unyielding, fibrous knot shows two sets of fibres :-(1) Those decussating
in the middle line; and (2) two sets of circular fibrous bundles which interlace at
the lateral boundaries of the ring. The lower part of the ring is stronger than the
upper. In other words, umbilical hernia of adult life, when it comes through the
ring itself and not at the side, always comes through the upper part. In the lower
three-fourths of the umbilicus, the umbilical arteries and urachus are firmly closed by
matting in a firm knot of scar-tissue; in the upper there is only the umbilical vein
and weaker scar. To the lower part run up the umbilical arteries and the urachus.
Owing to the rapid growth of the abdominal wall and pelvis before puberty, and
the fact that the urachus and the umbilical arteries, being of scar-tissue, elongate
with difficulty, the latter parts depress the umbilicus by reason of their intimate
connection with its lower half.
Coverings of an umbilical hernia. These, more or less matted together, are:-
(1) Skin; (2) superficial fascia, which loses its fat over the hernia; (3) prolonga-
tion of scar-tissue of the umbilicus gradually stretched out; (4) transversalis
fascia; (5) extra-peritoneal fatty tissue; (6) peritoneum. If the hernia come
through above the umbilicus, or just to one side, the coverings will be much the
same; but, instead of the layer from the umbilical scar, there will be one from
the linea alba.
noinen eie wod nin
yom! & otai began
Lesilidar
THE BACK
6 Бля вос
Median furrow. This is more or less marked according to the muscular
development, being between the complexi, chiefly in the cervical region, and the
erectores spinæ lower down. The lower end of the furrow corresponds to the
interval between the spines of the, last lumbar and the first sacral vertebræ.
(Holden.)
Vertebral spines.-Those of the upper cervical region are scarcely to be made
out even by deep pressure. That of the axis may be detected in a thin subject.
Over the spines of the middle three cervical vertebræ is normally a hollow, owing to
these spines receding from the surface to allow of free extension of the neck. The
seventh cervical is prominent, as its name denotes. Between the skull and atlas, or
between the atlas and axis, a sharp pointed instrument might penetrate, especially
in flexion of the neck.
Of the thoracic spines, the third should be noted as on a level with the inner end
of the scapular spine, and in some cases with the bifurcation of the trachea; that
of the seventh with the lower angle of the scapula; that of the twelfth with the
lowest part of the trapezius and the head of the twelfth rib. The obliquity and
overlapping of the thoracic spines is to be remembered.
Of the lumbar spines, the most important are the second, which corresponds to
the termination of the cord, and that of the fourth, which marks the highest part
of the iliac crests and the bifurcation of the abdominal aorta. The lumbar spines
project horizontally, and correspond with the vertebral bodies.
Owing to the obliquity of the thoracic spines, most of them do not tally with the
heads of the corresponding ribs. Thus, the spine of the second corresponds with
THE BACK M
1171
Triceps
FIG. 713.-FIRST LAYER OF THE MUSCLES OF THE BACK.

Sterno-mastoid
Deltoid
Trapezius
Teres minor
Infra-spinatus
Teres major
Rhomboideus major
Pectoralis major
Serratus magnus
Latissimus dorsi
Obliquus externus
Gluteus medius
Gluteus maximus
4 F 2

1172
SURGICAL AND TOPOGRAPHICAL ANATOMY
the head of the third rib; the spine of the third with the head of the fourth rib;
and so on, till we come to the eleventh and twelfth vertebræ, which do tally with
their corresponding ribs. (Holden.)
FIG. 714.--THE LEVATOR ANGULI SCAPULA AND RHOMBOIDEI.
Supra-spinatus
Infra-spinatus
Teres major.
Serratus magnus
Serratus posticus.
inferior
Obliquus internus
Complexus
Splenius capitis
Levator anguli scapulæ
Serratus posticus superior
Rhomboideus minor
Splenius colli
Rhomboideus major
SURFACE MARKINGS OF MUSCLES OF THE BACK 1173
Muscles. The student will remember the great number and complexity and
the numerous tendons of the muscles which run up on either side of the spine;
FIG. 715.-DIAGRAM AND TABLE SHOWING THE APPROXIMATE RELATION TO THE SPINAL
NERVES OF THE VARIOUS MOTOR, SENSORY, AND REFLEX FUNCTIONS OF THE SPINAL
CORD. Arranged by Dr. Gowers from anatomical and pathological data.)

edi
C
IC
2
MOTOR
SENSORY
REFLEX
C1
2
3
Neck and scalp
3
Sterno-mastoid
Trapezius
Neck and shoulder
3
Diaphragm
4
5
Serratus
5
Shoulder
Shoulder
6
6
8
--7
Arm
musc.
Arm
Scapular
7
DIV.7.
Hand
Hand
(ulnar lowest)
2
T1
D1
IT
2
32.
3
3
5
4.
4
4
6.
5
Front of thorax
--5
5
Epigastric
..6..
6
Intercostal
muscles
6
Ensiform area
8
7
7
7
9
8
8
8
10
9
9
9
=
10
-10
12
10
Abdominal
muscles
Abdomen
Abdominal
LI
11
12
1234555
11
(Umbilicus 10th)
12
-12
L1
Buttock, upper
part
IL
LI
2
2
2
Flexors, hip
Groin and scrotum
(front)
Outer side
Cremasteric
3
3
Extensors, knee
Thigh front
Knee joint
Adductors
+ 5
4
4
hip
Leg, inner side
5...
5
Abductors
inner side
Buttock, lower part
-Gluteal
S
S
IS
Extensors (?).
Flexors, knee (?)
Back of thigh
Muscles of leg
moving foot
Leg
3
Perinæal and anal
muscles
and except inner
foot part
Perinæum and anus
Foot clonus
Plantar olsegue
Co.
ed
30.
Skin from coccyx to
anus
the firmness and inextensibility of their sheaths; the large amount of cellular
tissue between them; and the fact that towards the nape of the neck these
muscles lie exposed instead of being protected in gutters, as is the case below: all
1174
SURGICAL AND TOPOGRAPHICAL ANATOMY
these anatomical points explain the extreme painfulness and obstinacy of sprains
here.
Trapezius. To map out this muscle, the arm should be raised to a right angle
with the spine. The external occipital protuberance should be dotted in, and the
superior nuchal line passing out from this; below, the twelfth thoracic spine should
be marked; and externally, the outer third of the clavicle and the commencement of
the scapular spine. Then a line should be drawn from the protuberance vertically
downwards to the twelfth thoracic spine; a second from about the middle of the
FIG. 716.-CHIEF ARTERIAL ANASTOMOSES ON THE SCAPULA.
(From a dissection in the Hunterian Museum.)
Supra-spinatus Suprascapular artery

Posterior scapular artery
Rhomboideus minor
Levator anguli scapulæ
Trapezius
Rhomboideus major
Teres major muscle
Infra-spinatus
Triceps
Deltoid, insertion
Deltoid
Deltoid muscle
Triceps
Teres major, insertion
Dorsalis scapulae artery Posterior circumflex artery
superior nuchal line to the posterior and outer third of the clavicle; and a third from
the last thoracic spine upwards and outwards to the spine of the scapula (fig. 713).
Latissimus dorsi.-The arm being raised above a right angle, the spines of the
sixth thoracic and the third sacral vertebræ should be marked; then the outer lip of
the crest of the ilium, the lower two or three ribs, the lower angle of the scapula,
and the posterior fold of the axilla, and finally the bicipital groove should all be
marked (fig. 713).
A vertical line from the sixth thoracic to the third sacral spine will give the
spinal origin of the muscle. Another from the third sacral spine to a point on
the iliac crest, an inch or more outside the edge of the erector spinæ, will give the


RELATION OF NERVES TO SPINES OF VERTEBRÆ 1175
origin of the muscle from the sheath of the erector spine and the ilium. A line
from the sixth thoracic spine, almost transversely at first, with increasingly slight
obliquity over the inferior angle of the scapula to the axilla and bicipital groove,
will mark the upper border of the muscle. Another very oblique line from the
point on the iliac crest upwards and outwards to the axilla will give the lower
border and the tapering triangular apex of the insertion. The muscle may be
attached to the angle of the scapula, or separated from it by a bursa.
Triangle of Petit.-This small space lies above the crest of the ilium, at about
its centre, bounded by the anterior edge of the latissimus and the posterior border
of the external oblique (fig. 713).
Origin of spinal nerves. It is very important to remember the relation of these
to the vertebral spines, in determining the results of disease or injury of the cord
and the parts thereby affected. The above relation may be given briefly as
follows:-
The origins of the eight cervical nerves correspond to the cord between the occiput
FIG. 717.-ARRANGEMENT OF LUMBAR APONEUROSIS AT LEVEL OF THIRD LUMBAR
VERTEBRA.

Rectus
Transversalis
Internal oblique
External oblique
Sacro-lumbalis
Latissimus dorsi
Quadratus lumborum
Longissimus dorsi
Psoas magnus
and the sixth cervical spine. The upper six thoracic come off between the above
spine and that of the fourth thoracic vertebra. The origins of the lower six thoracic
nerves correspond to the interval between the fourth and the tenth thoracic spines.
The five lumbar arise opposite the eleventh and twelfth thoracic spines; and the
origins of the five sacral correspond to the first lumbar spines. The diagram
and table (page 1173), arranged by Dr. Gowers from anatomical and pathological
data, show the relation of the origin of the nerves to their exit from the vertebral
canal, and the regions supplied by each.
Scapula, its muscles and arterial anastomoses.-Amongst the landmarks in
the back, the student should be careful to trace the angles and borders of the
scapula, as far as these are accessible. The upper border is the one most thickly
covered. The upper angle corresponds to the upper border of the second rib; the
lower angle to the seventh intercostal space; and the root of the spine of the
scapula to the interval between the third and fourth thoracic spines. Fig. 716 shows
the chief arteries around the scapula. The anastomoses on the acromial process
between the suprascapular, acromio-thoracic, and circumflex arteries are not shown.


1176
SURGICAL AND TOPOGRAPHICAL ANATOMY
Lumbar fascia.-In the loins, the muscles which fill in the space between the
last rib and the crest of the ilium should be carefully noted, owing to the frequency
of operations here. When the latissimus dorsi, the oblique, the transversalis, the
erector spinæ, and quadratus have been described, the lumbar fascia (the posterior
aponeurosis of the transversalis), and the three layers into which it divides posteriorly
(fig. 717) should be remembered.
Viscera. Several of these, which can be mapped in behind-viz. the kidneys,
FIG. 718.-RELATION OF THE ABDOMINAL VISCERA TO THE ANTERIOR PARIETES. (Treves.)
erode ods
LIVER
4
STOMACH
18
KIDNEY TRANS. COLON
KIDNEY 9
10
Eas
edT
dieg bers
spleen, etc.-have been already mentioned (page 1148). See also page 1148 for the
incision for lumbar colotomy.
The following table, from Holden and Windle, with additions, will be found very
useful in determining the relation of numerous viscera and other structures to the
vertebræ.
toon
First. Level of hard palate.
CERVICAL
Second. Level of free edge of upper teeth.
Second and third. Superior cervical ganglion of sympathetic.
RELATION OF STRUCTURES TO SPINES OF VERTEBRA 1177
Fourth. Hyoid bone.
Fifth. Middle cervical ganglion.
Sixth. Cricoid cartilage.
Seventh. Inferior cervical ganglion. Apex of lung, higher in the female than
in the male.
THORACIC
Second. Level of episternal notch. This is usually opposite the fibro-cartilage
between the second and third.
FIG. 719.-RELATION OF THE ABDOMINAL VISCERA TO THE POSTERIOR PARIETES. (Treves.)

SPLEEN
STOMACH
LIVER
KIDNEY
KIDNEY
K
RECTUM
Third. Level of junction between the manubrium and the gladiolus. This is
sometimes opposite to the fifth. Lowest limit of superior mediastinum. Bifurcation
of trachea.
Fourth. Second piece of aortic arch reaches spine.
Fifth. Termination of third piece of aortic arch.
togo Fifth to eighth. Base of heart.
Sixth. Pulmonary and aortic valves.
1178
SURGICAL AND TOPOGRAPHICAL ANATOMY
Seventh. Mitral orifice.
Eighth. Tricuspid orifice.
Ninth. Lower level of manubrium. Openings in diaphragm for inferior vena
cava and oesophagus. Upper limit of spleen.
FIG. 720.-ABDOMINAL VISCERA, FROM BEHIND. (Rüdinger.)

LARYNX
Aorta
-GULLET
BRONCHUS
LUNG
LUNG
DIAPHRAGM
PANCREAS
SPLEEN-
STOMACH
Vena cava
LIVER
DUODENUM
DESCENDING COLON
Inferior mesenteric
vein
Superior mesenteric
vein
ASCENDING COLON
Cardiac orifice of stomach.
Suprarenal capsule.
Tenth. Level of tip of xiphoid cartilage. Lower limit of lung posteriorly.
Liver comes to the surface posteriorly.
Eleventh. Lower border of spleen.
Twelfth. Lowest part of pleura.
border). Coeliac axis (lower border).
Aorta passes through diaphragm (upper
Pylorus. Upper border of kidney.


RELATION OF NERVES TO SPINES OF VERTEBRE 1179
LUMBAR
First. Pancreas. Pelvis of kidney. Renal arteries (ending).
Second. Spinal cord end, at junction of first and second. Third piece of
duodenum. Receptaculum chyli.
FIG. 721.-THE SUPERIOR AND INFERIOR VENE CAVE, THE INNOMINATE VEINS,
AND THE AZYGOS VEINS.
Right common carotid.
artery
Right internal jugular
vein
RIGHT LYMPHATIC DUCT
Innominate artery
Right innominate vein.
Internal mammary vein
Trunk of the pericardiac.
and thymic veins
Vena cava superior
Vena azygos major
Left common carotid
artery
PNEUMOGASTRIC
NERVE
THORACIC DUCT
-Left innominate vein
Left subclavian artery
Left superior
intercostal vein
RECURRENT
LARYNGEAL
NERVE
Vena azygos minor, cross-
ing spine to vena azygos
major
Hepatic veins
Esophageal arteries
Left upper azygos vein
Vena azygos minor
THORACIC DUCT
Right phrenic artery-
Coeliac axis
Middle suprarenal
artery
Left phrenic artery
Right spermatic artery
RECEPTACULUM CHYLI
Superior mesenteric
artery
Left ascending lumbar
vein
Left spermatic vessels
903
Inferior mesenteric
artery
Third. Umbilicus, opposite fibro-cartilage between this and fourth.
border of kidney.
Fourth. Bifurcation of aortic arch. Highest part of iliac crest.
Fifth. Commencement of superior vena cava.
Lower
1180
SURGICAL AND TOPOGRAPHICAL ANATOMY
FIG. 722.-VIEW OF THE SPLEEN, ETC. FROM BEHIND. (Rüdinger.)

LUNG
Diaphragm
STOMACH
SPLEEN
KIDNEY
DESCENDING
COLON
Psoas
SACRAL
Third. End of first piece of rectum. Lower limit of spinal membranes.
Coccyx (tip). End of second piece of rectum.
SUPERFICIAL ANATOMY OF THE UPPER LIMB
THE SHOULDER
The following surface-marks, of the greatest importance in determining the
nature of shoulder injuries, can be made out here:-The clavicle in its whole
extent, the acromion process, the great tuberosity, and upper part of the shaft of
the humerus. Much less distinctly, the position of the coracoid process and the
head of the humerus can be made out. The anterior margin of the clavicle,
convex internally and concave externally, can be made out in its whole extent,
the bone, if traced outwards, being found not to be horizontal, but rising somewhat
to its junction with the acromion. The tip of this process, when the arm hangs by
YYOTIZER THE SHOULDER
1181
адуг
the side, is in the same line as the external condyle and the styloid process of the
radius. On the inner side, the head and internal condyle of the humerus and the
styloid process of the ulna are in the same line. Thus the great tuberosity looks.
FIG. 723.-TRANSVERSE SECTION THROUGH THE RIGHT SHOULDER JOINT, SHOWING
THE STRUCTURES IN CONTACT WITH IT. (Braune.)

CLAVICLE
ACROMION
Supra-spinatus--
Trapezius
Infra-spinatus-
Teres minor
Teres major-
Latissimus dorsi--
Axillary vessels and NERVES
Deltoid
Pectoralis major
Tendon of subscapularis blended with
the scapular ligament
Coraco-brachialis and short head of biceps
FIG. 724.-THE PECTORALIS MAJOR AND DELTOID.
Sterno-
mastoid
Deltoid
-Biceps
Teres major
-Pectoralis major
Latissimus dorsi
Serratus magnus
Aponeurosis of external oblique
External intercosta

1182
SURGICAL AND TOPOGRAPHICAL ANATOMY
outwards, the head inwards, and the lesser tuberosity somewhat forwards. Between
the two tuberosities runs the bicipital groove, which, with the arm in the above
position, looks directly forwards (fig. 725). In thin subjects its lower part can be
defined. Besides the tendon and its synovial sheath, the insertion of the latissimus
dorsi, the humeral branch of the acromio-thoracic artery, and the anterior circumflex
FIG. 725.-SUPERFICIAL VIEW OF THE FRONT OF THE UPPER ARM.
Pectoralis minor
Coraco-brachialis
Deltoid
Biceps
Outer head of triceps
Inner head of triceps.
Brachialis anticus,
Semilunar fascia
Brachialis anticus
Extensor carpi radialis
longior
Brachio-radialis
artery run in the groove. When the fingers are placed on the acromion, and the
thumb in the axilla, the lower edge of the glenoid cavity can be felt; and if the
humerus be rotated (the elbow joint being flexed), the head of the humerus can be
felt also.
The characteristic roundness of the shoulder is due to the deltoid, supported
by the head of the humerus and the tuberosities (fig. 724). Close to the clavicle,

SURFACE MARKINGS OF THE SHOULDER
1183
between the contiguous origins of the pectoralis major and deltoid, is the infra-
clavicular fossa, in which lies the cephalic vein and the humeral branch of the
acromio-thoracic artery. On pressing deeply here, the coracoid process can be made
FIG. 726.-THE BRACHIAL ARTERY.
(From a dissection in the Museum of the Royal College of Surgeons.)
Suprascapular artery and NERVE
CIRCUMFLEX
NERVE
SUBSCAPULAR
NERVE
Subscapular vessels
Triceps
Basilic vein
ULNAR NERVE-
Triceps
Inferior profunda artery
Biceps
Axillary artery
and vein
MUSCULO-CUTA-
NEOUS and in-
ternally outer
head of MEDIAN
NERVE
One of the brachial
veins
Coraco-brachialis
INTERNAL
CUTANEOUS NERVE
Brachial artery-
MEDIAN NERVE
Cephalic vein
MUSCULO-
CUTANEOUS
NERVE
Supinator longus
Radial vein
Median vein
Radial artery
out if the muscles are relaxed and the axillary artery compressed against the second
rib.
On raising the arm and abducting it, the different parts of the deltoid can

1184
SURGICAL AND TOPOGRAPHICAL ANATOMY
often be made out-viz. fibres from the lower border of the spine of the scapula,
the outer edge of the acromion, and the outer third or more of the front of
the clavicle: the characteristic knitting of the surface owing to the presence of
muscular bundles, separated by depressions caused by the tendinous septa, will also
be seen. The muscle will be marked out by a base-line reaching along the above
bony points, and two sides converging from its extremities to the apex, a point
on the outer surface of the humerus, about its centre. To map out the pectoralis
major, a line should be drawn down the lateral aspect of the sternum as far as the
sixth costal cartilage, and then two others marking the borders of the muscle-the
upper corresponding to the deltoid, the lower starting from the sixth cartilage, and
the two converging to the folded tendon, which is inserted as a double layer into the
outer bicipital ridge. The pectoralis minor will be marked out by two lines, from
the
upper border of the third and the lower border of the fifth rib, just external to
FIG. 727.-SECTION THROUGH THE MIDDLE OF THE RIGHT UPPER ARM.
(Heath.)
Cephalic vein
Biceps
MUSCULO-CUTANEOUS
NERVE
Brachialis anticus-
MUSCULO-SPIRAL NERVE
Superior profunda vessels
Brachial vessels
MEDIAN NERVE
ULNAR NERVE
"Basilic vein, with internal
cutaneous nerves
Triceps, with fibrous intersection
Inferior profunda vessels
their cartilages, and meeting at the coracoid process. The lower line gives the
level of the long thoracic artery; the upper, where it meets the line of the axillary
artery, that of the acromio-thoracic.
When the arm is abducted and the humerus rotated a little outwards, the
prominence of a well-developed coraco-brachialis comes into view; a line drawn
from the centre of the clavicle along the inner border of this muscle to its insertion
into the humerus gives the line of the axillary artery.
The depression of the axilla is best marked when the arm is raised from the
side to an angle of about 45°, and when the muscles bounding it in front and
behind are contracted. In proportion as the arm is raised, the hollow becomes
less, the head of the humerus now projecting into it. When the folds are relaxed
by bringing the arm to the side, the fingers can be pushed into the space so as to
examine it.
The circumflex nerve and posterior circumflex vessels wind round the humerus
below the deltoid, a little above the centre of this muscle.

THE SHOULDER
1185
FIG. 728.-THE LOWER PART OF THE AXILLARY, THE BRACHIAL, AND THE RADIAL
AND ULNAR ARTERIES. odt
(From a dissection in the Hunterian Museum.)
CLAVICLE
BRACHIAL PLEXUS
ACROMION
HEAD OF HUMERUS
Pectoralis minor, turned back
MUSCULO-CUTANEOUS
NERVE
BRANCH OF MUSCULO-CUTA-
NEOUS TO MEDIAN NERVE
Coraco-brachialis
Subscapularis
Acromio-thoracic artery
Axillary artery
MEDIAN NERVE
Subscapular artery
Brachial artery
Superior profunda artery
Biceps
Teres major
Latissimus dorsi
Long head of triceps
MUSCULO-SPIRAL NERVE
MUSCULAR BRANCH OF
MUSCULO-SPIRAL NERVE
MUSCULO-CUTANEOUS.
NERVE
BRANCH OF MUSCULO-
CUTANEOUS NERVE TO
BRACHIALIS ANTICUS
Brachialis anticus-
MEDIAN NERVE
Inner brachial vena comes
MUSCULO-SPIRAL NERVE
Inferior profunda artery
Inner head of triceps
ULNAR NERVE
Anastomotica magna artery
Internal intermuscular septum
Radial recurrent artery
Supinator longus
Superficial median vein, cut short
MUSCULAR BRANCHES OF
MEDIAN NERVE
Pronator teres and superficial
flexor muscles, turned back
Anterior ulnar recurrent artery
Deep head of pronator radii
teres
Pronator radii teres
RADIAL NERVE
Radial artery
Cut edge of flexor sublimis
digitorum
MEDIAN NERVE
-Posterior ulnar recurrent artery
Superficial flexor muscles,
turned back
Anterior interosseous artery and
NERVE
Flexor profundus digitorum
- ULNAR NERVE
Flexor longus pollicis
Ulnar artery
Interosseous membrane with
cut edge of pronator
quadratus
4 G

1186
SURGICAL AND TOPOGRAPHICAL ANATOMY
THE ARM
The shaft of the humerus is well covered by muscles in the greater part of
its extent, especially above. Below the insertion of the deltoid, the outer border
of the bone can be traced downwards into the external supracondyloid ridge. The
inner border and ridge are less prominent. Attached to these ridges and borders
are the intermuscular septa, each lying between the triceps and brachialis anticus,
and the outer one giving origin to the brachio-radialis (supinator longus) and
FIG. 729.-BACK VIEW OF THE SCAPULAR MUSCLES AND TRICEPS.
Supra-spinatus
Infra-spinatus
Teres minor
Teres major.
Long head of triceps.
Outer head of triceps
Inner head of triceps
Anconeus
buraft to 3DS
extensor carpi radialis longior as well. The outer septum is perforated by the
superior profunda vessels and the musculo-spiral nerve, the inner by the inferior
profunda and anastomotica magna arteries and the ulnar nerve. On either side
of the well-known prominence of the biceps is a furrow. Along the outer
ascends the cephalic vein. The inner corresponds to the line of the basilic
vein which lies superficial to the deep fascia below the middle of the arm, and
superficial and internal to the brachial vessels and median nerve.
THE ARM
1187
A line drawn along the inner edge of the biceps from the insertion of the
teres major to the middle of the bend of the elbow corresponds to the brachial
artery. In the upper two-thirds this artery can be compressed against the bone
by pressure outwards; in its lower third the humerus is behind it and pressure
should be made backwards. The superior profunda comes off from the highest
part of the artery and courses with the musculo-spiral nerve (page 1188); the
FIG. 730.-DEEP VIEW OF THE FRONT OF THE UPPER ARM.

Pectoralis minor-
Short head of biceps-
-Long head of biceps
Coraco-brachialis-
об Биз
bas laiber ola
end to bood add of rots Inil
Long head of triceps-
Insertion of pectoralis major
Insertion of deltoid
galer
Inner head of triceps-
Internal intermuscular septum-
Brachialis
Insertion of biceps-
10
Lentire
digirl
Outer part of brachialis anticus
nutrient artery arises opposite the middle of the humerus; the inferior profunda
below the middle, and courses with the ulnar nerve through the intermuscular
septum to the back of the internal condyle. The anastomotica is given off from
one to two inches above the bend of the elbow.
The centre of the arm is a landmark for many anatomical structures. On the
outer side is the insertion of the deltoid; on the inner that of the coraco-brachialis.
The basilic vein and the nerve of Wrisberg here perforate the deep fascia, going in
reverse directions. The inferior profunda is here given off from the brachial; the
4 G 2

1188
SURGICAL AND TOPOGRAPHICAL ANATOMY
median nerve also crosses the artery, and the ulnar nerve leaves the inner side of
the vessel to pass to the inner aspect of the limb.
The brachialis anticus can be mapped out by two pointed processes which
surround the insertion of the deltoid, and which pass downwards into lines
corresponding to the two intermuscular septa, and then converge over the front of
the elbow to their insertion into the coronoid process.
The median nerve can be traced by a line drawn from the outer side of the
third part of the axillary and first part of the brachial artery, across this latter
vessel about its centre, and then along its inner border to the forearm, where it
passes between the two heads of the pronator radii teres.
The ulnar nerve lies to the inner side of the above arteries as far as the middle
of the arm, where it leaves the brachial to course more inwards and perforate the
internal intermuscular septum and get to the back of the internal condyle.
The musculo-spiral nerve can be traced by a line beginning behind the third
part of the axillary artery, then carried vertically down behind the uppermost part
of the brachial, and then, just below the posterior border of the axilla, curving
backwards behind the humerus and slightly downwards, just below the insertion of
the deltoid. Thus, passing from within outwards and from before backwards in its
groove with the superior profunda vessels, it again comes to the front by perforating
the external intermuscular septum at a point about opposite to the junction of the
middle and lower thirds of the arm, and passes down in front of the external supra-
condyloid ridge, lying here between the brachio-radialis and brachialis anticus, to
the level of the external condyle, where it divides into radial and posterior inter-
osseous. The former of these accompanies the radial artery to the front of the
arm, the latter travels backwards to the back of the forearm.
On the back of the arm is the triceps muscle, with its three heads and tendon of
insertion, all brought into relief in a muscular subject when the forearm is strongly
extended. Of the three heads the inner is the least distinct, arising below the
musculo-spiral groove, reaching to each intermuscular septum, and tapering away
above as high as the teres major. The outer head, arising above the groove as high
as the great tuberosity, appears in strong relief just below the deltoid; while the
middle or long head, arising from the scapula just below the glenoid cavity, appears
between the teres muscles. The tendon of insertion, passing into the upper and back
part of the olecranon over a deep bursa, is shown by a somewhat depressed area.
FIG. 731.-VERTICAL SECTION OF THE ELBOW. (One-half.) (Braune.)
Tendon of biceps-.
Brachio-radialis.
RADIAL NERVE-
Brachialis anticus.---
Extensor carpi radialis---
longior
Anconeus..
Pronator teres
-MEDIAN NERVE
-Flexor carpi radialis
Internal lateral ligament
ULNAR NERVE
--OLECRANON
-Tendon of triceps
THE ELBOW
The bony points, condyles, olecranon, and head of radius, and their relation to
each other, should be carefully studied. The internal condyle is the more prominent
of the two, is directed backwards as well as inwards, and lies a little above its
fellow. Above it can be traced upwards the supracondyloid ridge and corresponding
THE ELBOW
1189
septum. The external condyle is more rounded, and thus less prominent; below,
and a little behind it, the head of the radius can be felt moving under the
FIG. 732.-LONGITUDINAL SECTION OF THE ELBOW JOINT. (One-half.) (Braune.)

Triceps-
Extensor carpi ulnaris
Biceps
-Brachialis anticus
-MUSCULO-SPIRAL NERVE
-Brachio-radialis
-Supinator brevis
Extensor carpi radialis
longior
FIG. 733.-BEND OF THE ELBOW. (One-half.) (Blandin.)
INTERNAL CUTANEOUS NERVE
Brachial aponeurosis
Basilic vein.-.
Brachial aponeurosis
Cephalic vein
Median basilic vein-
Epitrochlea-
Abnormal vessel
Superficial ulnar vein
Brachial artery and vence----
comites
Bicipital fascia--.
Anti-brachial aponeurosis-
CUTANEOUS BRANCH OF
MUSCULO-SPIRAL NERVE
Slip of brachial aponeurosis
passing to muscles attached
to external condyle
EXTERNAL CUTANEOUS
NERVE
Abnormal vessel
...Median cephalic vein
Superficial radial vein
Anti-brachial aponeurosis
Deep radial vein Median vein
capitellum when the forearm is supinated and flexed. A depression marks this spot
and corresponds to the interval between the anconeus and brachio-radialis and
exterior carpi radialis longior; at the back the upper part of the olecranon is

1190
SURGICAL AND TOPOGRAPHICAL ANATOMY
covered by the triceps. The lower is subcutaneous, and separated from the skin by
a bursa. If the thumb and second finger be placed on the condyles and the index
on the tip of the olecranon, and the forearm completely extended, the tip of the
olecranon rises so as to be on the line joining the two condyles. In flexion at a
right angle, the olecranon is below the line of the condyles, and in complete flexion
quite in front of them. Between the inner condyle and olecranon is a pit, in which
lie the ulnar nerve and the anastomosis between the inferior profunda and the
FIG. 734.-THE BEND OF THE ELBOW WITH THE SUPERFICIAL VEINS.
(From a dissection by Dr. Alder Smith in the Museum of St. Bartholomew's Hospital.)
Biceps
MEDIAN NERVE-
Anastomotica magna.
BRANCHES
OF INTERNAL
CUTANEOUS NERVE
Posterior ulnar vein-
Brachialis anticus-
Anastomotica magna
artery
Anterior ulnar vein
Median basilic vein-
MUSCULAR BRANCH-
OF MEDIAN NERVE
Tendon of biceps-
Bicipital fascia-
Brachialis anticus-
Deep median vein-
Ulnar artery-
Pronator teres-
Basilic vein
Brachialis
anticus
Cephalic vein
Brachial artery
EXTERNAL
CUTANEOUS
NERVE
MUSCULO-SPIRAL
NERVE and ascend.
br. of radial recur. art.
Radial vein
Median cephalic
vein
Ascending br. of
radial recurrent art.
RADIAL
NERVE
-Radial recurrent
artery
Brachio-
radialis
Descending br. of
radial recurrent
artery
-Median vein
Radial artery.
RADIAL
NERVE
posterior ulnar recurrent arteries. The coronoid process is so well covered by
muscles, vessels, and nerves, that its position cannot be distinctly made out.
Swelling, due to effusion into the joint, appears on either side of the triceps
tendon, and soon obliterates the depression below the external condyle. A super-
ficial swelling over the tip of the olecranon is due to effusion into the bursa between
the soft parts and that bone. A deeper, less easily defined, swelling in the same
region is due to inflammation of the bursa between the olecranon and the triceps. A
swelling on the inner side of the elbow joint, if painful and accompanied by inflam-
mation of the skin, may be due to mischief in the epitrochlear gland situated just

YMOTIVE THE ELBOW A DIDAUS
1191
above the internal condyle, and receiving lymphatics from the inner border of the
forearm and the two inner fingers.
The hollow in front of the elbow. The delicateness of the skin here must
always be borne in mind in the application of splints. The M-like arrangement of
the superficial veins as usually described is by no means constant (figs. 733, 734).
The median basilic is the vein usually chosen for venesection, owing to its larger
size and its being firmly supported by the subjacent bicipital fascia which separates
it from the brachial artery; but the median cephalic is the safer. The median basilic
is crossed by branches of the internal cutaneous nerve, while those of the musculo-
cutaneous lie under the median cephalic. In the semiflexed position, the fold of the
FIG. 735.-THE BRACHIAL ARTERY AT THE BEND OF THE ELBOW.
POSTERIOR BRANCH
OF INTERNAL
CUTANEOUS NERVE
ANTERIOR BRANCH-
OF INTERNAL
CUTANEOUS NERVE
BRANCH OF
MUSCULO-SPIRAL
NERVE TO
BRACHIO-RADIALIS
RADIAL NERVE
BRANCH TO
PRONATOR TERES
Bicipital fascia, cut-
Radial recurrent artery
and POSTERIOR
INTEROSSEOUS
NERVE
MUSCULO-
CUTANEOUS NERVE
MEDIAN NERVE-
elbow is seen, a little above the level of the joint. This forms the base of the trian-
gular fossa below the elbow, the outer side corresponding to the brachio-radialis,
the inner to the pronator radii teres, and the apex to the meeting of these muscles.
The tendon of the biceps can be easily made out in the centre of the fossa, giving off
above the bicipital fascia from its inner side to fasten down the flexors of the forearm.
Under the tendon on its inner side lie the brachial artery and the median nerve for
a short distance. The musculo-spiral lies outside the fossa, between the brachio-
radialis and the brachialis anticus. The brachial usually bifurcates opposite to the
neck of the radius.
The arterial anastomoses about the elbow joint are as follow: The radial
recurrent runs up under cover of the brachio-radialis to anastomose with the

1192
SURGICAL AND TOPOGRAPHICAL ANATOMY
superior profunda. The anterior ulnar recurrent ascends on the brachialis anticus to
join the anastomotica magna under the pronator radii teres. The posterior ulnar
recurrent makes for the interval between the internal condyle and the olecranon, to
FIG. 736.-THE ARTERIES OF THE FOREARM WITH THE DEEP PALMAR ARCH.
Brachial artery
Inferior profunda artery
Anastomotica magna artery
Radial recurrent artery-
Anterior ulnar recurrent
Posterior ulnar recurrent
Brachio-radialis
Radial artery on flexor longus-
pollicis
-Anterior interosseous artery
-Flexor carpi ulnaris
Collateral branch of
palmar digital artery
Anterior interosseous artery
Anterior branch of ulnar
artery
-Deep palmar arch
-Palmar digital artery, cut
short
join with the inferior profunda and anastomotica magna. The posterior interosseous
recurrent ascends, between the supinator brevis and the anconeus, to anastomose
on the back of the joint with the superior profunda.
THE FOREARM
1193
THE FOREARM
Bony landmarks.-The ulna can be easily traced down from the olecranon to
the styloid process; the bone becomes somewhat rounded below, and lies between
FIG. 737.-FRONT OF THE FOREARM: FIRST LAYER OF MUSCLES.

Triceps
Brachialis anticus
Biceps
Pronator radii, teres
Brachio-radialis
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
Flexor longus pollicis
Flexor sublimis digitorum
the flexor and extensor carpi ulnaris. The tip of the styloid process corresponds
to the inner end of the line of the wrist joint. The radius is covered above by the
1194
SURGICAL AND TOPOGRAPHICAL ANATOMY
brachio-radialis and radial extensors of the carpus, and the outline of the bone is
less easily followed. Its styloid process is readily made out below, a finger's breadth
above the thenar eminence. It is placed on a slightly higher level than that of the
FIG. 738.-FRONT OF THE FOREARM: SECOND LAYER OF MUSCLES.

Biceps
Triceps
Muscles of first layer
Brachialis anticus
Flexor sublimis digitorum
Brachio-radialis
Extensor carpi radialis longior
Supinator brevis
Brachio-radialis
Flexor carpi ulnaris
Flexor longus pollicis
Flexor carpi radialis
Palmaris longus
-Extensor ossis metacarpi pollicis
Extensor brevis pollicis
styloid process of the ulna. Thus, a line drawn straight between the two processes
would fall a little below that of the wrist joint, this being shown by a line drawn
between the two processes forming a slight curve, with its concavity downwards
THE FOREARM
1195
(corresponding to the concavity of the lower surface of the radius and fibro-cartilage)
about half an inch above the straight line given above.
The radial styloid process is covered by the extensor ossis metacarpi and primi
internodii pollicis, while immediately farther out lies that of the extensor secundi.
The bones are nearest to each other in complete pronation, and farthest apart in
complete supination. On section, the bones are found at every point nearer to the
back than to the front of the limb, but increasingly so above. The lower the
section proceeds down the limb, the less will the bones be covered at the sides, and
the more equally will the soft parts be distributed about the anterior and posterior
aspects of the limb. It will be noticed that where one bone is the most substantial
the other is the more slender, as near the elbow and wrist; and that it is about the
centre of the limb that the two are most nearly of equal strength' (Treves). When
the limb is pronated, the interosseous space is narrowed; in supination and the mid-
position it is widened out. In pronation, both styloid processes can be distinctly
FIG. 739.-SECTION THROUGH THE MIDDLE OF THE RIGHT FOREARM. (Heath.)

Brachio-radialis-
Supinator brevis.
Extensores carpi radialis-
longior and brevior
Extensor ossis metacarpi-
pollicis
Anterior inter-
osseous vessels
and NERVE
Radial vessels
and NERVE
Pronator teres
Flexor carpi
radialis
Flexor sublimis digitorum
-Flexor carpi ulnaris
Extensor communis digitorum
Extensor carpi ulnaris
Posterior interosseous vessels and NERVE
Ulnar vessels and NERVE
Flexor profundus digitorum
MEDIAN NERVE
Extensor secundi internodii pollicis
made out; in supination, that of the radius is most distinct, as now the skin and soft
parts are stretched and raised over that of the ulna.
Soft parts. Along the outer border descend the brachio-radialis and radial
extensors of the carpus, fleshy above, tendinous below. About an inch and a half
above the styloid process of the radius, a fleshy swelling directed obliquely down-
wards and forwards from behind, across this outer border of the forearm, denotes
the extensors of the thumb crossing those of the carpus.
Along the inner border is the fleshy mass of the pronator teres and flexors, the
ulna being covered by the flexor carpi ulnaris and flexor profundus. The tendon
of the pronator is inserted into the radius a little below its centre - a point of
importance in the treatment of fractures, and in amputation. The flexor carpi ulnaris
tendon can be felt just above the wrist making for the pisiform bone; and just
external to it lies the ulnar artery, about to pass over the anterior annular ligament.
The course of the artery is denoted by a line drawn from the front of the internal

1196
SURGICAL AND TOPOGRAPHICAL ANATOMY
condyle to the outer edge of the pisiform bone. If it be drawn from the bifurcation.
of the brachial, this line must in its upper third be made strongly convex inwards,
in order to mark the upper part of the artery, here thickly covered by muscles.
The line of the ulnar nerve is one drawn from the interval between the internal
FIG. 740.-SUPERFICIAL NERVES OF THE FOREARM.
ANTERIOR BRANCHES OF-
INTERNAL CUTANEOUS
-Biceps
INTERNAL CUTANEOUS
EXTERNAL CUTANEOUS
Deep fascia of forearm-
Palmaris longus
Flexor carpi radialis
MEDIAN PALMAR.
CUTANEOUS
condyle and the olecranon to the inner side of the ulnar artery just above the wrist.
The nerve joins the artery at the junction of the upper and middle thirds of the
forearm. The median nerve runs in a line drawn from the inner side of the
brachial artery, in the elbow triangle, to a point beneath or just to the inner side
of the palmaris longus just above the wrist. The radial artery will be marked by
THE FOREARM
1197
a line drawn from the centre of the bend of the elbow (where the brachial artery
divides opposite to the neck of the radius) to a point just internal to the radial
styloid process descending along the inner edge of the brachio-radialis. The radial
nerve will be marked by the same line (it lies just external to the artery) for its
upper two-thirds; it then leaves the artery about three inches above the wrist joint,
and passes to the back of the forearm under the tendon of the brachio-radialis.
The anterior interosseous artery runs down on the interosseous membrane and
passes to the back of the forearm by perforating it below. The posterior interosseous
lies between the superficial and deep extensors. These small arteries reinforce the
FIG. 741.-DISTRIBUTION OF CUTANEOUS NERVES ON THE ANTERIOR AND POSTERIOR
ASPECTS OF THE SUPERIOR EXTREMITY.

INTERNAL
CUTANEOUS OF
MUSCULO-SPIRAL-
INTERNAL
CUTANEOUS
SUPRA-ACROMIAL
CIRCUMFLEX
INTERCOSTO-
HUMERAL
TWIG OF
INTERNAL
CUTANEOUS
EXTERNAL
CUTANEOUS OF
MUSCULO-SPIRAL
MUSCULO-
CUTANEOUS
PALMAR
CUTANEOUS OF
MEDIAN
PALMAR
CUTANEOUS OF
ULNAR
PALMAR
CUTANEOUS
OF RADIAL
CIRCUMFLEX
EXTERNAL
CUTANEOUS OF
MUSCULO-SPIRAL
MUSCULO-
CUTANEOUS
SUPRA-
ACROMIAL
INTERNAL
CUTANEOUS OF
MUSCULO-SPIRAL
INTERCOSTO-
HUMERAL
-NERVE OF
WRISBERG
INTERNAL
CUTANEOUS
RADIAL
ULNAR
palmar through the carpal arches, and thus bring down blood after ligature of the
trunks above.
The front of the forearm is supplied by the musculo-cutaneous on the outer, and
the internal cutaneous on the inner side; just above the wrist the palmar cutaneous
branches of the median and ulnar perforate the deep fascia (figs. 740, 741). The
back of the forearm is supplied by the musculo-spiral and posterior branches of the
musculo-cutaneous externally, and the posterior branches of the internal cutaneous
internally (fig. 741). The arrangement of the superficial lymphatics is shown in
fig. 742.

1198
SURGICAL AND TOPOGRAPHICAL ANATOMY
THE WRIST AND HAND
Bony points. On the inner side, the styloid process and, farther outwards, the
head, of the ulna can be made out. On the outer side, the radial styloid process
FIG. 742.-SUPERFICIAL VEINS AND LYMPHATICS OF THE FOREARM AND ARM.
External jugular vein
Pectoralis major
Pectoralis major, hooked up
Supraclavicular gland
Jugulo-cephalic vein
-Deltoid muscle
Lymphatics from side of
chest
Lymphatics accompanying
cephalic vein
Axillary glands
Pectoral glands
Cephalic vein
Lymphatic vessels of inner
side of arm
Basilic vein
Epitrochlear gland
Posterior superficial
ulnar vein
Median basilic vein
Inner set of superficial.
lymphatics of forearm
Deep median vein
INTERNAL CUTA-
NEOUS NERVE
Anterior superficial
ulnar vein
Median set of superficial
lymphatics of forearm
Biceps, exposed
MUSCULO-CUTANEOUS
NERVE
Brachial artery
Bicipital fascia
Median cephalic vein
Superficial radial vein
Superficial median vein
-Outer set of superficial
lymphatic vessels of fore-
arm
ZMOWE THE WRIST AND HAND
1199
descends about half an inch lower than that of the radius, and is somewhat anterior
to it. Abduction of the hand is thus less free than adduction. In Colles' fracture,
the line of fracture, usually transverse, crosses the radius about an inch above the
apex of the styloid process. Between the apex of the styloid process and the ball
of the thumb a bony ridge can be felt, with some difficulty, formed by the tubercle
of the scaphoid and the ridge of the trapezium. At a corresponding point on the
inner side the pisiform can be more readily distinguished. On the front of the
metacarpo-phalangeal joint of the thumb the sesamoid bones can be distinguished.
At the back of the wrist and hand the cuneiform bone can be felt below the head
of the ulna; and more towards the middle line the prominence of the os magnum,
which supports the third or longest digit, and is the bone of the carpus most exposed
to injury. A line drawn from the base of the fifth metacarpal bone to the radio-
carpal joint, slightly curved downwards, will give the line of the carpo-metacarpal
joints. (Windle.)
FIG. 743.-RELATION OF THE PALMAR ARCHES TO THE FOLDS OF THE PALM. (Tillaux.)

Superficial palmar arch---
Deep palmar arch-
Superficialis volæ
-Inferior fold
Middle fold
Superior fold
Ulnar artery
Radial artery
When the fingers are flexed, it will be seen that in each case it is the proximal
bone which forms the prominence; thus, the knuckle is formed by the head of the
metacarpal, the interphalangeal prominence by the head of the first phalanx, and
the distal one by the head of the second. Thus, the joint in each case lies below
the prominence, the distal joint being one-twelfth of an inch, the interphalangeal
one-sixth, and the metacarpo-phalangeal one-third below its prominence.
Skin folds. Two or three of these are seen on the palmar surface of the wrist;
two lower down, and usually close together; and one less well marked a little higher
up upon the forearm. None of these correspond exactly to the wrist joint (page 1194).
The lowest precisely crosses the arch of the os magnum in the line of the third
metacarpal bone' (Tillaux), and is not quite three-quarters of an inch below the
arch of the wrist joint. It is about half an inch above the carpo-metacarpal joint
line, and indicates very fairly the upper border of the anterior annular ligament.
The thenar and hypothenar eminences are separated by a triangular interval
with the apex upwards; this apex corresponds to the upper border of the
anterior annular ligament. Of the many creases in the skin of the palm, three


1200
SURGICAL AND TOPOGRAPHICAL ANATOMY
require especial notice. The first starts at the wrist, between the thenar and hypo-
thenar eminences, and, marking off the former eminence from the palm, ends at
the outer border of the hand at the base of the index finger. The second fold is
slightly marked. It starts from the outer border of the hand, where the first fold
ends. It runs obliquely inwards across the palm, with a marked inclination towards
the wrist, and ends at the outer limit of the hypothenar eminence. The third,
FIG. 744.-ANASTOMOSES AND DISTRIBUTION OF THE ARTERIES OF THE HAND.
Anterior interosseous
Radial artery
Anterior radial carpal
Superficial volar
Posterior radial carpal
Radial artery at wrist-
Dorsalis pollicis
Metacarpal or first
dorsal interosseous
Princeps pollicis
Dorsalis indicis
Ulnar artery
Anterior ulnar carpal
Posterior ulnar carpal
Deep ulnar
-Superficial arch
Carpal recurrent
Posterior communicating
or perforating
Radialis indicis.
Dorsal digital
Collateral digital-
First dorsal branch of-
collateral digital
Second dorsal branch of-
collateral digital
Palmar interosseous
Second, third, and fourth
palmar digital
Second and third dorsal
interosseous
First palmar digital
Anterior communicating
or perforating
Anastomosis of collateral.
digital arteries about
matrix of nail and pulp
of finger
lowest, and best-marked of the folds starts from the little elevation opposite the
cleft between the index and middle fingers, and runs nearly transversely to the ulnar
border of the hand, crossing the hypothenar eminence at the upper end of its lower
fourth. An unimportant crease, running obliquely from the third to the second
fold, gives to these markings the outline of the letter M. The first fold is produced
by the adduction of the thumb; the second, mainly by the bending simultaneously
THE WRIST AND HAND
1201
of the metacarpo-phalangeal joints of the first and second fingers; and the third
by the flexion of the three inner fingers. The second fold, as it crosses the third
metacarpal bone about corresponds to the lowest part of the superficial palmar
arch. The third fold crosses the necks of the metacarpal bones, and indicates.
FIG. 745.-THE DEEP LAYER OF THE BACK OF THE FOREARM.

Anconeus
Supinator brevis
Flexor carpi ulnaris
Extensor ossis metacarpi pollicis
Flexor profundus digitorum
Extensor brevis pollicis
Extensor longus pollicis.
Radial extensors
Extensor indicis
Extensor carpi ulnaris
pretty nearly the upper limits of the synovial sheaths for the flexor tendons of the
three outer fingers. A little way below this fold, the palmar fascia breaks up into
its four slips, and midway between the fold and the webs of the fingers lie the
metacarpo-phalangeal joints. Of the transverse folds across the fronts of the fingers,
corresponding to the metacarpo-phalangeal and interphalangeal joints, the highest
4 H

1202
SURGICAL AND TOPOGRAPHICAL ANATOMY
is placed nearly three-quarters of an inch below its corresponding joint. The middle
folds are multiple for all the fingers, and are exactly opposite to the first inter-
phalangeal joints. The lowest creases are single, and are placed a little above the
FIG. 746.-THE SUPERFICIAL MUSCLES OF THE PALM OF THE HAND.
Flexor carpi
ulnaris
Anterior annular
ligament
Palmaris longus
Palmaris brevis
Abductor minimi
digiti
Flexor brevis
minimi digiti
Flexor sublimis
digitorum
Ligamentum
vaginale
Tendon of
flexor
profundus
Flexor
sublimis
digitorum
Flexor profundus
digitorum
Flexor carpi radialis
Extensor ossis metacarpi pollicis
Opponens pollicis
Abductor pollicis
Flexor brevis pollicis
Adductor pollicis
First lumbri
calis
First dorsal
interosseous
Ligamentum vaginale
Flexor sublimis digitorum
Flexor profundus digitorum
corresponding joints. There are two single creases on the thumb corresponding to
the two joints, the higher crossing the metacarpo-phalangeal joint obliquely. The
free edge of the web of the fingers, as measured from the palmar surface, is about
three-quarters of an inch from the metacarpo-phalangeal joints.' (Treves.)
THE WRIST AND HANDE
1203
The superficial palmar arch, formed by the ulnar anastomosing with the
superficialis volæ, or radialis indicis, will be shown by a line descending to the radial
FIG. 747.-MUSCLES OF THE RADIAL SIDE AND THE BACK OF THE FOREARM.

goak
Biceps
Brachialis anticus-
Brachio-radialis
Extensor carpi radialis longior-
-Triceps
Anconeus
Extensor communis digitorum.
-Flexor carpi ulnaris
-Extensor carpi ulnaris
Extensor carpi radialis brevior.
Extensor minimi digiti
Extensor ossis metacarpi
pollicis
Extensor brevis pollicis
Extensor longus pollicis
ULNA
How gaming
Aroda
side of the pisiform bone, and then, a little lower, coming across the palm on a line
with the thumb when outstretched at right angles with the index finger. The
4 H 2

1204
SURGICAL AND TOPOGRAPHICAL ANATOMY
digital arteries, the main branches of the superficial arch, run downwards along
the interosseous spaces, and bifurcate half an inch below the webs of the fingers; the
innermost digital does not bifurcate. The digital arteries then descend along the
sides of the fingers under the digital nerves, giving off twigs to the sheath of
the tendons, which enter by apertures in it, and run in the vincula vasculosa. It is
owing to the readiness with which these tiny twigs are strangled by inflammation
FIG. 748.-THE DEEPER MUSCLES OF THE PALM OF THE HAND.
Flexor carpi
ulnaris
Abductor-
minimi digiti
Flexor sublimis.
digitorum
Flexor brevis
minimi digiti
Flexor profun-.
dus digitorum
Extensor ossis metacarpi
pollicis
Flexor carpi radialis
Extensor brevis pollicis
Abductor pollicis
Opponens pollicis
Lum-
bricales
First
dorsal
inter-
osseous
Abductor
pollicis
Flexor
brevis
pollicis
Adductor
pollicis
that sloughing of the tendon takes place so readily and irreparably. The deep
palmar arch, formed by the radial and communicating branch of the ulnar, lies
about half an inch nearer to the wrist than the superficial.
Fascia and sheaths.-The two annular ligaments bind down and hold in place
the numerous tendons about the wrist. The anterior, when healthy, cannot be
detected. It is attached to the pisiform and cuneiform bones on the inner, and to
the scaphoid and trapezium on the outer, side. The ulnar nerve and vessels, the
THE WRIST AND HAND
1205
superficialis volæ, and palmar cutaneous of the median and ulnar pass over it; the
flexor carpi radialis passes through a separate sheath formed by the ligament and
the groove in the trapezium; while beneath the ligament lie the flexor tendons, the
median nerve, and accompanying artery. Attached to its upper border is the deep
FIG. 749.-SECTION THROUGH REGION OF WRIST, A LITTLE ABOVE THE JOINT. RIGHT
SIDE, UPPER HALF OF THE SECTION. (Tillaux.)
Flexor carpi radialis Flexor longus pollicis
Radial artery
Flexor sublimis

Brachio-
radialis
Flexor profundus
Pronator quadratus
RADIAL NERVE
Extensor ossis meta-
carpi pollicis
Extensor primi
internodii pollicis
Extensor carpi radialis
longior
Extensor carpi radialis
brevior
Extensor secundi internodii
pollicis
Ulnar artery, more
internally the NERVE
Anterior interosseous
artery
Flexor carpi ulnaris
ULNA
Extensor com-
munis
RADIUS
Extensor carpi
ulnaris
Extensor indicis
fascia of the forearm, and to its lower the palmar fascia and the palmaris longus
tendon, while from the outer and inner parts arise some of the thenar and hypo-
thenar muscles. The upper border of the anterior annular ligament corresponds to
FIG. 750.-TRANSVERSE SECTION OF THE WRIST, THROUGH THE MIDDLE OF THE
PISIFORM BONE.
Sheath of flexores sublimis and profundus digitorum and flexor longus pollicis,
enclosed by true annular ligament

Cut tendon of palmaris longus
SEMILUNAR BONE
ULNAR NERVE
Ulnar vessels
Sheath for flexor carpi radialis,
Radial origin of annular ligament,
Sheath for extensor ossis metacarpi.
and primi internodii pollicis
Radial vessels'
Sheath for extensor ossis metacarpi---
and primi internodii pollicis
OS MAGNUM
Sheath of extensor secundi.
internodii pollicis
SCAPHOID"
CAPISIFORM
CUNEIFORM
Sheath of extensor
carpi ulnaris
Sheath of extensor minimi digiti
Sheath of extensores carpi radialis, longior and brevior
CUNEIFORM
Sheath of extensor communis and indicator UNCIFORM
SEMILUNAR
the lower of the two lines which cross the wrist just above the thenar and hypothenar
eminences. The large synovial sheath, for all the flexors of the fingers, reaches
beneath and below the anterior ligament as far as the middle of the palm, and
above the wrist for an inch and a half or two inches.
1206
SURGICAL AND TOPOGRAPHICAL ANATOMY
The posterior annular ligament is attached to the back of the outer margin of
the radius above the styloid process, and internally to the back of the cuneiform
and pisiform. It contains six tendon-compartments, of which four are on the
radius. The outermost contains the two first extensors of the thumb; the second
the two radial extensors of the carpus; the third, the extensor secundi internodii ;
the fourth transmits the extensor communis and extensor indicis; the fifth, lying
between the radius and ulna, the extensor minimi digiti; and the sixth, lying
just outside the styloid process of the ulna, the extensor carpi ulnaris. The sheaths
for the last two extensors are the only ones which follow the tendons to their
insertion, the others ending at a varying distance below the annular ligament. The
lower border of the posterior corresponds to the upper margin of the anterior
annular ligament.
FIG. 751.-DIAGRAM OF THE GREAT PALMAR BURSA.

Ulnar portion of palmar
bursa
Radial portion of palmar
bursa
Anterior annular ligament
-Lumbricalis
Deep
transverse
ligament
Superficial
transverse
ligament
-Theca
The palmar fascia, by its strength, toughness, numerous attachments, and
intimate connection with the superficial fascia and skin, is well adapted to protect
the parts beneath from pressure. The thenar and hypothenar muscles are enclosed
in two processes, which are thinner so as not to interfere with the contraction of the
subjacent muscles. The central part, pointed above at its attachment to the
annular ligaments, spreads out fan-like below, and gives off four slips which
bifurcate into two processes, which are attached to the sides of the first phalanx
of each finger and into the transverse ligament which ties the heads of the
metacarpal bones together. Transverse fibres pass between the processes into
which each of the four slips bifurcate, and thus form the beginning of the theca,
which is continued down to the finger to the base of the last phalanx. It is the

THE WRIST AND HAND
1207
contraction of the palmar fascia, especially of the slips to the two inner fingers,
which gives rise to Dupuytren's contraction.
Synovial membranes. Beneath the anterior annular ligament lie two
FIG. 752.-SECTION OF CARPUS, THROUGH THE UNCIFORM BONE. (Two-thirds.)
(Bellamy after Henle.)
MEDIAN NERVE
Flexor longus pollicis Flexor sublimis and profundus

Flexor carpi radialis
Thenar muscles
BASE OF FIRST METACARPAL BONE
Ulnar vessels and NERVE
Palmaris brevis
Hypothenar muscles
Extensor ossis
metacarpi pollicis
TRAPEZIUM
Extensor primi internodii
pollicis
Radial vessels-
Extensor carpi radialis longior.
TRAPEZOID
External carpi radialis brevior
Extensor carpi ulnaris
Extensor minimi digiti
UNCIFORM
OS MAGNUM Extensor communis digitorum
Extensor indicis
synovial sacs, one for the flexor longus pollicis, and one for the superficial and
deep flexors of the fingers. They extend above the annular ligament from one and a
quarter to one and a half inch below. That for the long flexor of the thumb reaches
to the base of the last phalanx. That for the finger-flexors gives off four processes.
FIG. 753.-HORIZONTAL SECTION OF THE HAND THROUGH THE CARPO-METACARPAL
JOINTS. (Bellamy after Henle.)
Volar aponeurosis
Flexor tendon in the sheath
Deep volar aponeurosis

Interosseous
Lumbricales
Anterior carpal ligament
Flexor tendon in the sheath
Deep volar aponeurosis
Lumbricalis
Interossei
Lumbricales
Flexor tendon in the sheath
Lumbricales
Anterior carpal ligament
Flexor tendon in the sheath
Interossei
Hypothenar muscles
Interossei
The one for the little finger also reaches to the base of the last phalanx. Those
for the index, middle, and third fingers, end about the middle of the meta-
carpal bones.
Traced from the insertions of the flexor profundus, the digital ·
1208
SURGICAL AND TOPOGRAPHICAL ANATOMY
synovial sheaths extend upwards into the palm as far as the bifurcation of the
palmar fascia (page 1206), i.e. into a point about opposite to the necks of the
metacarpal bones, denoted on the surface by the crease which corresponds to
FIG. 754. TENDONS UPON THE DORSUM OF THE HAND.

Extensor ossis metacarpi
pollicis
Extensor brevis pollicis
Posterior annular ligament
Extensor carpi
radialis brevior
Extensor carpi
radialis longior
Extensor longus
pollicis
First dorsal
interosseous
Adductor
pollicis
Tendon of first dorsal
interosseous
Attachment of exten-.
sor communis digi-
torum to second
phalanx
Attachment of exten-.
sor communis digi-
torum to third pha-
lanx
Extensor carpi ulnaris
Extensor communis
digitorum
Extensor minimi
digiti
Extensor indicis
the flexion of the fingers. Thus, about half an inch separates the sheaths of the
outer three fingers from that large synovial sac beneath the annular ligament.
There is no synovial sheath beneath the pulp of the fingers or thumb, this part
THE WRIST AND HAND
1209
lying on the periosteum of the last phalanx. The synovial sheaths, as they pass
beneath the annular ligament, are somewhat constricted.
Deeper down are the articular synovial sacs, five in number: (1) Between the
interarticular cartilage and the head of the ulna; (2) between the radius and the
interarticular cartilage above, and the scaphoid, and semilunar and cuneiform below;
(3) between the trapezium and first metacarpal bone; (4) between the pisiform
and the cuneiform bone; (5) between the two rows of carpal bones, sending two
FIG. 755.-DIAGRAM OF A VERTICAL SECTION THROUGH THE MIDDLE OF THE HAND.

Posterior annular ligament
-Great palmar bursa
Anterior annular ligament
Deep transverse ligament
Attachment of common
extensor to first pha-
lanx
Dorsal interosseous
Lumbricalis
Palmar fascia
Flexor profundus digitorum
Flexor sublimis digitorum
Superficial transverse
ligamenc
Vincula accessoria
Attachment of common
extensor to
phalanx
second
Attachment of common
extensor to third pha-
lanx
Theca
Ligamentum vaginale
Vincula accessoria
processes upwards between the three bones of the upper row, and three downwards
between the four of the lower row; these three processes being also continued below
into the inner four carpo-metacarpal and three intermetacarpal joints.
Beneath the palmar fascia covering the thenar eminence are the following
structures:-Superficialis volæ, abductor pollicis, opponens pollicis, radial head of
short flexor, tendon of long flexor, ulnar head of short flexor, princeps pollicis, and
1210
SURGICAL AND TOPOGRAPHICAL ANATOMY
radialis indicis arteries, metacarpal bone of the thumb, with the tendon of the
flexor carpi radialis and trapezium.
Beneath the central part of the palmar fascia are the superficial arch and its
digital branches, the ulnar and median nerves with their branches, the flexors,
superficial and deep, with their synovial sheath, and the lumbricales; then a layer
of connective tissue (the only structure which prevents matter pent in by the
palmar fascia from making its way back out of the dorsum), the deep arch, the
interossei, and the metacarpal bones.
In the hypothenar eminence under the fascia are part of the ulnar artery and
nerve, the abductor and flexor brevis minimi digiti, the opponens, the deep branch
of the ulnar artery and nerve, and the fifth metacarpal bone.
The back of the wrist and hand.--The posterior annular ligament has already
been described with the anterior. On the outer side is the so-called 'snuff-box
space' (tabatière anatomique of Cloquet), a triangular hollow, bounded towards the
radius by the two first extensors of the thumb, and towards the ulna by the
extensor secundi internodii. The scaphoid and trapezium, with their dorsal liga-
ments, form the floor. In the roof lie the radial vein and branches of the radial
nerve. More deeply is the artery following a line from the apex of the styloid pro-
cess to the back of the interosseous space. The different tendons have already
been given. Between the first two metacarpal bones is the first dorsal interosseous
muscle, which forms a fleshy projection against the radial side of the index meta-
carpal, when the thumb and index are pressed together. On its palmar aspect is
the adductor pollicis. Wasting of the former muscle is a ready indication of injury
or disease of the ulnar nerve.
THE LOWER EXTREMITY
THE THIGH
Bony landmarks. Many of these, such as the anterior superior spine, the spine
of the pubes, have already been mentioned.
Trochanter major. This most valuable landmark is most prominent when the
limb is rotated inwards or adducted; it lies at the bottom of a depression when the
femur is everted. The only structures of importance between it and the skin are
the expanded insertion of the gluteus maximus and the bursa beneath the muscle.
This is often multilocular. The top of the great trochanter is about three-quarters
of an inch below the level of the femoral head.
Nélaton's line. This most useful guide is a line drawn from the anterior
superior spine to the most prominent part of the tuberosity of the ischium. In
normal limbs, the top of the great trochanter just touches this line. In dislocation,
fractures of the neck, and in wasting of the neck as in osteo-arthritis, the relation
of the trochanter to Nélaton's line becomes altered.
The top of the great trochanter is a guide in Mr. Adams's operation for division
of the neck of the femur, the puncture being made and the saw entered one inch
above and about one inch in front of this point.
Bryant's triangle. Mr. Bryant makes use of the following in deciding the
position of the great trochanter. The patient being flat on his back, (1) a line
is dropped vertically on to the couch from the anterior superior spine; (2) from
the top of the great trochanter a straight line in the long axis of the thigh is drawn to
meet the first; (3) to complete the triangle, a line is drawn from the anterior

THE THIGH
1211
superior spine to the top of the trochanter. This line is practically Nélaton's. The
second line will be found diminished on the damaged or diseased side.
Muscular prominences. The tensor vaginæ femoris (ilio-aponeurotic muscle)
forms a prominence beginning just outside the sartorius and reaching downwards
and somewhat backwards to the strong fascia lata, three to four inches below the
great trochanter. Below this point, as far as the outer tuberosity of the tibia, the
strong ilio-tibial band can be felt. The sartorius, the chief landmark of the thigh,
forming a boundary of Scarpa's triangle, Hunter's canal, and the popliteal space,
can be readily brought into view by the patient's raising his limb. In the middle
line, the rectus muscle stands out in bold relief, with its tendon of insertion and
the patella, when the leg is extended. On either side of this muscle is a furrow,
FIG. 756.-TRANSVERSE SECTION OF THE HIP JOINT AND ITS RELATIONS.
(One-third.) (Braune.)

ANTERIOR
CRURAL
NERVE IN SUB-
STANCE OF ILIACUS.
INTERNUS
External iliac artery-
Gluteus minimus
ILIUM-
Gluteus medius
Obturator internus-
Adductor magnus
Obturator externus----
Adductor longus..
Adductor brevis..
Pectineus
Ilio-psoas
and on either side, again, of this furrow the vasti become prominent. Between
the vastus internus and adductor muscles is a depression indicating Hunter's
canal. At the upper and inner third of the thigh, if the limb be abducted,
the upper part of the adductor longus comes into strong relief. On the inner side
below, above the knee joint, the vertical fibres of the adductor magnus end in
a powerful tendon coming down to the adductor tubercle (fig. 768). This replaces
here the internal intermuscular septum, and the insertion of the tendon marks the
level of the lower epiphysial line of the femur. At the outer and back part of the
thigh the vastus externus is separated from the biceps by a groove which indicates
the external intermuscular septum.
Poupart's ligament. The abdomen is separated from the thigh by a fold,
1212
SURGICAL AND TOPOGRAPHICAL ANATOMY
best marked in flexion--the inguinal furrow. In this, pressure detects the meeting
of the aponeurosis of the external oblique and the fascia lata, i.e. Poupart's ligament,
extending between the anterior superior spine and the spine of the pubes. The
FIG. 757.-MUSCLES OF THE FRONT OF THE THIGH.

Psoas
Iliacus
Gluteus medius
Pectineus
Gluteus minimus
Tensor vaginæ femoris
Adductor brevis
Adductor longus
Gracilis
Adductor magnus
Vastus internus
Tendon of sartorius
Sartorius
Rectus femoris
Ilio-tibial band of fascia lata
Vastus externus
Ligamentum patellæ
line representing it should be drawn slightly convex downwards, owing to the
attachment of the deep fascia. It forms the base of Scarpa's triangle; its inner
attachment blends with the triangular Gimbernat's ligament. Besides the inguinal
THE THIGH
1213
furrow, Mr. Holden describes a second, seen when the thigh is slightly bent, and
crossing outwards from the angle between the scrotum and the thigh across the
front of the latter, to be gradually lost between the top of the great trochanter and
the anterior superior spine. When present (for it is not constantly well marked) it
is a valuable landmark, as it runs right across the capsule of the hip joint, and is
thus useful in suspected hip joint disease, as pressure made in this line will tell if
the joint be tender. In amputation through the hip joint by anterior and posterior
flaps, if the knife be introduced deeply along this line, the capsule will be exposed
or even opened at the first thrust.
Scarpa's triangle (fig. 758).-Immediately below Poupart's ligament, a hollow
is seen corresponding to this region, the outer and inner boundaries of which
are brought into view when the limb is raised, the adductor longus especially
when the limb is abducted, and the sartorius where the thigh is flexed and
FIG. 758.-SECTION OF THE RIGHT THIGH AT THE APEX OF SCARPA'S
EXTERNAL CUTANEOUS NERVE
TRIANGLE. (Heath.)
Profunda vessels
Femoral vessels

Sartorius
Adductor longus
SUPERFICIAL OBTURATOR NERVE
Rectus femoris
ANTERIOR CRURAL
NERVE
External circumflex-
vessels
Tensor fasciæ femoris
Vastus internus and
crureus
Vastus externus-
Biceps femoris
Semi-tendinosus
SMALL SCIATIC NERVE
GREAT SCIATIC NERVE
Gracilis
Pectineus
Adductor brevis
DEEP OBTURATOR
NERVE
Adductor magnus
Semi-membranosus
adducted and carried towards its fellow. Lying superficially in the base of the
triangle, the lymphatic glands can be detected in a thin person (fig. 790). They
lie in two groups-(a) One horizontal in a line with Poupart's ligament, and
receiving lymph from the genitals, the lower part of the abdominal wall, and
the inner aspect of the buttock; (b) a vertical set lying along the great vessels
receiving lymph from the limb. According to Mr. Treves, a few of the superficial
genital lymphatics, and all those from the perinæum, go into the vertical group.
Saphenous opening. The depression corresponding to this is placed just below
Gimbernat's ligament, with which its upper extremity blends. Its centre is about
an inch and a half below and also external to a line dropped vertically from the
pubic spine. This and the other structures concerned in femoral hernia are fully
described under this section (vide supra, page 1166).
Line of femoral artery.-A line drawn from the mid-point between the anterior
superior spine and the symphysis pubis to the adductor tubercle will correspond
1214
SURGICAL AND TOPOGRAPHICAL ANATOMY
with the course of this vessel. The sartorius usually crosses it, three to four
inches below Poupart's ligament. The profunda artery arises an inch and a
half to two inches below Poupart's ligament. Therefore the incision for tying the
femoral in Scarpa's triangle should be about three inches long, in the line of
the artery, and begin about three inches below Poupart's ligament, and run over the
apex of the triangle. The vein lies below Poupart's ligament, immediately to the
inner side of the artery. From this point the vein gets on to a somewhat deeper
FIG. 759.-SUPERFICIAL DISSECTION OF THE FRONT OF THE THIGH.
(Hirschfeld and Leveillé.)

Poupart's ligament
EXTERNAL CUTANEOUS NERVE
MIDDLE CUTANEOUS NERVE
OUTER DIVISION OF INTERNAL
CUTANEOUS NERVE
MIDDLE CUTANEOUS NERVE
BRANCH TO SARTORIUS
EXTERNAL CUTANEOUS NERVE
Superficial branches of femoral
artery
Femoral artery
Femoral vein
INNER DIVISION OF INTERNAL
CUTANEOUS NERVE
Saphena vein
INNER DIVISION OF INTERNAL
CUTANEOUS NERVE
CUTANEOUS BRANCH OF
OBTURATOR NERVE
SARTORIUS PLEXUS
OUTER DIVISION OF INTERNAL
CUTANEOUS NERVE
OUTER DIVISION OF INTERNAL
CUTANEOUS NERVE
MIDDLE CUTANEOUS NERVE
INNER DIVISION OF INTERNAL
CUTANEOUS NERVE
PATELLA
pi Veloflreque
gil a'ving
PATELLAR BRANCH OF LONG
SAPHENA
LONG OR INTERNAL SAPHENOUS
NERVE
Innitolda od:
plane, though still very close to the artery, and gradually inclining backwards, lies
behind its companion at the apex of the triangle, and below lies somewhat to its
outer side.
From the apex of Scarpa's triangle a depression runs down along the inner aspect
of the thigh, corresponding to the groove already mentioned (page 1211) between
the vastus internus and the adductors. Along this groove lies the sartorius, and
beneath it Hunter's canal. The vein has here got somewhat to the outer side.
The long saphenous nerve lies also in the canal, but not in the sheath. The above-
mentioned space terminates at about the junction of the middle and lower thirds of
the thigh, in the opening in the adductor magnus by which the artery enters the


LYLARDA THE THIGH
1215
upper and inner part of the popliteal space. The long saphenous, the largest
branch of the anterior crural nerve, having crossed the femoral vessels from without
inwards, accompanies them as far as the opening in the adductor magnus. Here it
perforates the aponeurosis, and is prolonged under the sartorius, accompanied by
the superficial part of the anastomotic artery, to become cutaneous and run with
the long saphena vein at the upper and inner part of the leg.
Pressure may be applied to the femoral artery (1) Immediately below Poupart's
FIG. 760.-ANTERIOR CRURAL AND OBTURATOR NERVES. (Ellis.)
Femoral vein
Pectine us
OBTURATOR (ANTERIOR DIV.)
OBTURATOR (POSTERIOR
DIVISION)
Adductor longus-
Adductor brevis-
OBTURATOR-
(ANTERIOR
DIVISION)
Gracilis-
Adductor magnus
GENICULATE
BRANCH OF
OBTURATOR
Semi-membranosus
Anastomotica artery
PATELLAR BRANCH OF
LONG SAPHENOUS
Femoral artery

Sartorius
Iliacus
ANTERIOR CRURAL
Psoas
-Tensor vaginæ femoris
Profunda artery
Pectineus
Rectus femoris
LONG SAPHENOUS
NERVE TO VASTUS
INTERNUS
Adductor longus
Femoral artery
ligament: it should here be directed backwards so as to compress the vessel
against the brim of the pelvis and the capsule of the hip joint; (2) at the apex
of Scarpa's triangle, the pressure here being directed outwards and a little back-
wards, so as to command the vessel against the bone; (3) in Hunter's canal the
pressure should be directed outwards, with the same object. Care must be taken,
especially above, to avoid the vein, which lies very close to the artery, and also the

1216
SURGICAL AND TOPOGRAPHICAL ANATOMY
anterior crural nerve, which enters the thigh about half an inch outside the artery,
and at once breaks up into its branches, superficial and deep.
FIG. 761.-SIDE VIEW OF PELVIS AND UPPER THIRD OF THIGH, WITH THE EXTERNAL
ILIAC, INTERNAL ILIAC, AND FEMORAL ARTERIES AND THEIR BRANCHES.
(From a dissection by W. J. Walsham in the Museum of St. Bartholomew's Hospital.)
The bladder is hooked over to expose the back of the pelvis.
Common iliac artery
SYMPATHETIC NERVE
Middle sacral artery
Common iliac vein
URETER.
Internal iliac artery-
External iliac vein-
External iliac artery-
Posterior br. of internal iliac dividing.
into gluteal and ilio-lumbar arteries
Lateral sacral artery"
SACRAL PLEXUS-
OBTURATOR NERVE-
Obturator artery-
Obliterated hypogastric
Psoas muscle
-Ilio-lumbar artery
EXTERNAL CUTANEOUS
NERVE
Iliacus muscle
GENITO-CRURAL NERVE
-ANTERIOR CRURAL NERVE
Superior vesical artery-
Edge of levator ani
Pudic artery-
BLADDER
Middle vesical artery-
Deep epigastric artery-
Pubic br. of epigastric.
artery
Common femoral artery-
Long saphenous vein-
Pectineus muscle-
Obturator artery-
Adductor magnus-
Internal circumflex artery-
Adductor brevis-
OBTURATOR NERVE (ant. branch)-
Profunda arter y-
Adductor longus, hooked aside.
Superficial femoral artery and vein.
Deep circumflex iliac artery
Superficial circumflex iliac arter
ANTERIOR CRURAL NERVE
Gluteal artery and nerve
Tensor fasciæ femoris (hooked
aside)
Gluteus medius and minimus
-Sartorius muscle
MIDDLE CUTANEOUS NERVI
NERVE TO RECTUS
NERVE TO VASTUS
EXTERNUS
External circumflex artery
NERVE TO CRUREUS
Rectus, hooked aside
Profunda vein
NERVE
LONG SAPHENOUS
AND
INTERNUS
NERVE TO VASTUS
Gracilis muscle
Lower part of sartorius.
Vastus internus muscle
THE BUTTOCKS
Bony landmarks. The finger readily traces the whole outline of the iliac
crest. Behind, it terminates in the posterior superior spine, which corresponds in
level to the second sacral spine and the centre of the sacro-iliac joint. (Holden.)
The third sacral spine marks the lowest limit of the spinal membranes and the
cerebro-spinal fluid; it also corresponds to the upper border of the great sacro-
sciatic notch.
The first piece of the coccyx corresponds to the spine of the ischium (Windle).
Its apex
is in the furrow just behind the last piece of the rectum.
THE BUTTOCKS
1217
The tuberosities of the ischium are readily felt by deep pressure on either side
of the anus. In the erect position they are covered by the lower margin of the
gluteus maximus. In sitting they are protected by tough skin, fasciæ, a matted
FIG. 762.-THE DEEP MUSCLES OF THE FRONT OF THE THIGH.

Obturator externus
Rectus tendon
Gluteus medius
Adductor longus
Gluteus minimus
Adductor magnus.
Adductor longus
Adductor brevis
Vastus internus
Vastus externus
Vastus internus
Rectus femoris
Biceps
-Ilio-tibial band
Ligamentum patellæ
pad of coarse fibrous fat, and often by a bursa known, according to the patients in
whom it becomes enlarged, as weaver's, coachman's, lighterman's, drayman's' bursa.
Gluteus maximus.-The 'fold of the buttock' neither corresponds accurately to,
4 I
1218
SURGICAL AND TOPOGRAPHICAL ANATOMY
FIG. 763.-SUPERFICIAL MUSCLES OF THE BACK OF THE THIGH AND LEG.

Gluteus medius
Aponeurosis of gluteus
maximus
Biceps
Gluteus maximus
Semi-membranosus
Semi-tendinosus
Vastus externus
Gracilis
Tendon of semi-membranosus
Plantaris
Gastrocnemius
Soleus
Sartorius
Peroneus longus
Flexor longus digitorum
'Tendo Achillis
THE BUTTOCKS
1219
nor is caused by, the lower margin of this muscle. It is really due to creasing of
the skin in flexion and extension. But in early hip disease, in which flexion of
the joint is almost unvaryingly present, both the fold and the gluteus maximus
disappear with characteristic rapidity. The prominence of the buttock is mainly
due to the gluteus maximus, especially behind and below, and in less degree to the
other two glutei in front. Under the lower edge of the gluteus maximus the edge
of the great sacro-sciatic ligament can be felt on deep pressure.
Nerves and vessels.-The following superficial nerves can be marked in over the
buttock (fig. 791). Behind the great trochanter, branches of the external cutaneous.
Coming down over the crest, the lateral cutaneous branch of the last dorsal (about
in a line with the great trochanter), and behind this the lateral branch of the ilio-
hypogastric. Two or three offsets of the posterior primary branches of the lumbar
nerves cross the hinder part of the iliac crest at the outer margin of the erector spinæ.
Two or three twigs from the posterior divisions of the sacral nerves pierce the
FIG. 764.-SECTION THROUGH THE HIP AND GLUTEAL REGION. (One-third.)

Sartorius
Reflected tendon
rectus
Psoas and iliacus
and bursa
ANTERIOR
CRURAL NERVE
Common femoral.
artery
Common femoral.
vein
Profunda vessels-
Gracilis
Semi-membranosus-
Adductor brevis-
Semi-tendinosus.
Obturator externus-
Adductor longus-
Adductor magnus.
Gluteus maximus
Gluteus medius
Gluteus minimus
Pyriformis
GREAT SCIATIC
NERVE and sciatic
vessels
- Obturator internus
---Gemelli
Biceps
Quadratus femoris
gluteus maximus close to the coccyx and sacrum, and ramify outwards. Finally,
over the lower border of the gluteus maximus turn upwards branches of the small
sciatic and inferior pudendal nerves.
Great sciatic nerve (figs. 765, 766).-The point of emergence below the gluteus
maximus and the track of this nerve will be given by a line drawn from one a
little internal to the middle of the space between the great trochanter and the tuber
ischii to the lower part of the back of the thigh. The inferior pudendal perforates
the deep fascia about an inch in front of the tuber ischii, and turns forwards to
supply the genitals.
Gluteal artery. If a line be drawn from the posterior superior spine to the
apex of the great trochanter, the limb being slightly flexed and rotated inwards,
the point of emergence of the artery from the upper part of the great sacro-sciatic
notch will correspond with the junction of the upper and middle third of this line
(MacCormac). The gluteal nerve emerges immediately below the artery, and
sends branches with the deeper portion.
Sciatic and pudic arteries. The limb being rotated inwards, a line is drawn
412

1220
SURGICAL AND TOPOGRAPHICAL ANATOMY
from the posterior superior spine to the outer part of the tuber ischii. The point
of exit of the above arteries will correspond to the junction of the middle and lower
thirds of this line. (MacCormac.)
FIG. 765.-THE GLUTEAL REGION, WITH THE GLUTEAL, SCIATIC, AND PUDIC ARTERIES.
(From a dissection by W. J. Walsham in St. Bartholomew's Hospital Museum.)
The inferior gluteal branch of the sciatic artery has been drawn inwards over the tuber ischii
with the reflected origin of the gluteus maximus muscle.
Gluteus medius, turned up
INFERIOR GLUTEAL NERVE
Gluteus maximus, cut
Internal circumflex artery
Obturator externus
Insertion of gluteus medius
Gluteus minimus
Muscular branches of sciatic artery
Deep branch of gluteal artery
SUPERIOR GLUTEAL NERVE
External circumflex artery
GREAT TROCHANTER
Pyriformis perforated by peroneal
portion of sciatic nerve
Cut edge of gluteus maximus
TUBER ISCH
Pudic artery and nerve
Insertion of
gluteus maximus
First perforating artery
Quadratus femoris
Branch of internal circumflex artery
Obturator internus with the two gemelli
Biceps
Sciatic artery
Semi-tendinosus
Semi-membranosus
LESSER SCIATIC NERVE
Arteria nervi comes ischiatici
POPLITEAL PORTION OF GREAT SCIATIC NERVE
LONG PUDENDAL NERVE
PERONEAL PORTION OF GREAT SCIATIC NERVE
THE KNEE
Bony landmarks. The patella, the condyles, the tuberosities of the tibia, the
tubercle of the tibia, the head of the fibula.
The patella.-The extensor muscles being relaxed, the numerous longitudinal
striæ or sulci on the anterior surface of this bone can be detected. In these are
embedded tendinous bundles of the rectus, so as to give firmer leverage. The fact
that these fibres, thus tied down, are liable to fold in between the ends of the bone
after fracture, is a ready explanation of the difficulty of ensuring bony union here
(MacEwen). The patella articulates with the femur, and is separated from the
THE KNEE
1221
FIG. 766.-DEEP DISSECTION OF THE GLUTEAL REGION. (From a preparation in
the Hunterian Museum.)

Gluteus medius
[Gluteus minimus
Pyriformis, divided
into two by the
great sciatic nerve
GREAT TROCHANTER
Obturator
externus
GREAT SACRO-SCIATIC
FORAMEN
GLUTEAL NERVE
SUPPLYING POR-
TIONS OF GLU-
TEUS MEDIUS
Gluteus maximus
Quadratus femoris
Obturator in-
ternus. Below
is the inferior
gemellus. The
superior gemel-
lus is absent
Fascial insertion
of gluteus
maximus
Horizontal fibres
of adductor
magnus
Fleshy insertion
of gluteus
maximus
BRANCHES OF
INFERIOR
PUDENDAL
NERVE
GREAT SCIATIC NERVE.
Under it, oblique fibres of
adductor magnus are seen
SMALL SCIATIC NERVE
FIG. 767.-HORIZONTAL SECTION OF THE KNEE JOINT. (One-half.)
doider

PATELLA-
Synovial membrane-
Capsule,
FEMUR---
Crucial ligaments--
Biceps.
Outer head of gastrocnemius.
Popliteal artery
EXTERNAL POPLITEAL
NERVE
Popliteal vein
INTERNAL POPLITEAL NERVE
--Inner head of gastrocnemius.
-Sartorius
-Gracilis
Semi-membranosus
Semi-tendinosus
External saphena vein
1222
SURGICAL AND TOPOGRAPHICAL ANATOMY
tibia by a pad of fat and a deep bursa, save at its insertion. It has the following
relation to the femur in different positions :-(1) In extension, the patella rises up
over the condyles, and in full extension only the lower third of its articular surface
rests upon that of the condyles; its upper two-thirds lies upon the bed of fat which
covers the lower and front part of the femur. (2) In extreme flexion, as the
prominent anterior surface of the condyles affords leverage to the quadriceps, the
patella needs to project very little; thus, only its upper third is in contact with
the femur, its lower two-thirds now resting on the pad of fat between it and the
tibia. (3) In semiflexion the middle third of the patella rests upon the most prominent
part of the condyles (Humphry). While the bone now affords the greatest amount
of leverage to the quadriceps, it is also submitted to the greatest amount of strain
from this muscle, which is acting almost at a right angle to the long axis of the
patella. This position may therefore be called 'the area of danger,' as in a sudden
and violent contraction the patella may be snapped across by muscular action,
aided by the resistance given by the condyles, in the same way as a stick is snapped
across the knee.
Dislocation of the patella.-The following anatomical facts account for this
taking place much more frequently outwards :-(1) The inner edge of the patella
is more prominent, and thus more exposed to injury; it is also less well supported,
as is seen when, the parts being relaxed, the fingers are insinuated beneath each
border. (2) The pull of the extensor upon the patella, ligamentum patellæ, and
tibia is somewhat outwards, as the tibia is directed a little outwards to the femur,
to meet the inward direction of this bone; the femurs being directed inward here,
to bring the knee joints nearer the centre of gravity, and, so, counterbalance their
wide separation above at the pelvis. The outward pull of the quadriceps upon the
patella is, in all normal action of the muscle, counteracted by the space taken in the
trochlear surface by the external condyle, this being wider and creeping up higher,
and having a more prominent and thus protective lip. In violent contraction,
however, these counteracting points may be overcome.
The condyles and tuberosities. It should be noted that on the inner side the
prominence of the internal condyle is well marked, and that of the tibial tuberosity
is less so, while on the outer side this condition is reversed. Descending to the
outer tuberosity, the ilio-tibial band of the fascia lata can be traced. The more
distinct outer tuberosity is a good landmark for opening the joint in amputation
and incision. It also indicates the lower level of the synovial membrane of the
knee joint. The gap on the inner side between condyle and tuberosity is the place
for feeling for a displaced internal fibro-cartilage in 'internal derangement' of the
knee. On each condyle, posteriorly, in a thin subject can be felt their tubercles,
which give attachment to the lateral ligaments. Owing to their being placed
behind the centre of the bone these ligaments become tight in extension. On the
upper part of the internal condyle the adductor tubercle and the vertical tendon of
the adductor magnus can be felt during flexion. This bony point is a guide to the
lower epiphysis of the femur, one of the latest to join, uniting with the shaft about
the twenty-first year. It is a common site for exostoses in adolescents. The inner
aspect of this condyle faces practically in the same direction as the head of the
femur.
Ligamentum patellæ and tubercle of tibia. These, in a well-formed leg,
should, with the centre of the ankle joint, be all in the same straight line, a useful
point in the adjustment of fractures (Holden). Behind the upper half of the
ligament is the synovial membrane of the knee joint; below, the lower is separated
from the tibia by a deep bursa. In connection with all the posterior surface is fat,
which serves as a useful packing in the different movements of flexion and
extension. The tubercle of the tibia is on the same level with the head of the
fibula.


THE KNEE
1223
Prepatellar bursa. This usually protects the patella and upper part of the
ligamentum patellæ. It is liable to be enlarged in those who habitually kneel
much. Its close connection with the patella and, at the sides, with the joint itself
is to be remembered in inflammations of the bursa. Usually, two processes of
FIG. 768.-THE DEEP MUSCLES OF THE BACK OF THE THIGH.

Gluteus minimus
Obturator internus
Obturator externus
Gluteus maximus
Vastus externus
Short head of biceps
Adductor magnus
Crureus
Vastus internus
Tendon of biceps
fascia lata, passing off from the sides of the patella upwards to the thigh and
downwards to the leg, serve to conduct inflammation away from the joint.
Synovial membrane (fig. 769).-This, the largest in the body, is best seen in
cases of effusion. It extends upwards as a large cul-de-sac beneath the patella and
quadriceps expansion to a point above the patella, varying from two to two and a
half inches, or three fingers' breadth. On the inner side, the upper limit is about
1224
SURGICAL AND TOPOGRAPHICAL ANATOMY
three inches above the level of the joint, but not so high under the vastus externus.
Braune has described a deep bursa above the upper limit of the synovial membrane
between the quadriceps and the femur. The external tibial tuberosity marks the
lower limit of the synovial membrane, this level passing a little above the tubercle
of the tibia and head of the fibula.
FIG. 769.-VERTICAL SECTION OF THE KNEE JOINT IN THE ANTERO-POSTERIOR DIRECTION.

Muscular fibres of quadricep
extensor
Extension of synovial sac
of knee upon femur
Tendon of quadriceps ex-
tensor, forming fibrous
capsule of joint
Fatty tissue.
Opening in synovial
membrane behind
crucial ligament
leading into inner
Thalf of joint
Synovial membrane-
reflected off crucials
Cut end of anterior.
crucial ligament
Posterior crucial
ligament
Ligament of-
Winslow
PATELLA
-Pre-patellar bursa
CONDYLE OF FEMUR
(INNER)
Ligamentum
mucosum
Fatty tissue between
ligamentum patellæ
and synovial sac
Bursa beneath ligamentum
TIBIA
patellæ
The following explanations may be given of an inflamed knee joint usually taking
the flexed position. (1) By experimental injections, Braune found that the capacity
of the synovial sac reaches its maximum with a definite degree of flexion, i.e. at an
angle of twenty-five degrees. (2) As the same nerves supply the synovial membrane
and the muscles which act upon the joint, the flexors being more powerful than the
extensors will help to explain the flexed position. (Hilton.)

POPLITEAL SPACE
1225
POPLITEAL SPACE
In flexion the hollow of this space appears; in extension it is obliterated and
its boundaries are ill-defined, the only one now to be made out being the semi-
tendinosus and the biceps.
Popliteal tendons (fig. 770).-When the knee is a little bent and the foot rests on
the ground, the following can be made out: At the outer side, behind the ilio-tibial
FIG. 770.-THE EXTERNAL ROTATORS AND THE HAMSTRING MUSCLES.

Gluteus medius
Pyriformis
Gemellus superior.
Gemellus inferior.
Quadratus femoris
Obturator internus
Gluteus maximus.
Vastus externus
Biceps
Adductor magnus
Gracilis
Semi-tendinosus
Semi-membranosus
Crureus
Short head of biceps
Plantaris
Sartorius
Semi-tendinosus
Gastrocnemius

1226
SURGICAL AND TOPOGRAPHICAL ANATOMY
band, and descending to the head of the fibula, is the tendon of the biceps. Parallel
and close to its inner border, the external popliteal nerve descends as a rounded
cord. In tenotomy of the biceps, the knife should be introduced between it and
the tendon, and made to cut from within outwards, and thus away from the nerve.
On the inner side the tendons are thus arranged: Nearest to the middle of the
popliteal space is the long and more slender tendon of the semi-tendinosus ; next, the
thicker tendon of the semi-membranosus; this and the gracilis, which comes next,
FIG. 771.-SIDE VIEW OF THE POPLITEAL ARTERY. (From a dissection in the
Hunterian Museum.)
INTERNAL
SAPHENOUS NERVE-
BRANCHES OF THE
INTERNAL CUTA-
NEOUS NERVE
Sartorius
Insertion of adductor-
magnus
Anastomotica magna-
artery
LONG SAPHENOUS
NERVE
Vertical fibres of the
adductor magnus
Popliteal artery
Vastus internus
Cut edge of fascia lata-
BRANCH OF SAPHE-
NOUS NERVE TO
PATELLAR PLEXUS
Internal saphenous
vein
Gracilis
Part of
semi-tendinosus
appear as one tendon, but by a little manipulation the finger can be made to sink
into the interval between the semi-membranosus, with its thick rounded border
externally and the gracilis internally. The sartorius can only be thrown into relief
on the inner side of the joint by telling the patient to put it into action.
Bursæ. Five or six may exist at the back of the joint. Thus, on the inner side
there are three, viz.: (1) Largest and most often enlarged, usually called the popliteal
bursa, is the one between the tendon of the semi-membranosus and inner head of
the gastrocnemius-this communicates with the joint as often as once in every five
POPLITEAL SPACE
1227
cases (Holden); (2) one between the gastrocnemius and inner condyle; (3) one
between the semi-membranosus and back of the tibia. On the outer side there may
be (4) one between the outer head of the gastrocnemius and the condyle; (5) one
between the tendons of the popliteus and the outer tuberosity of the joint; (6) one
between the above tendons and the external lateral ligament; (7) one between the
biceps tendon and the same ligament. While some of the above communicate with
the joint much more frequently than the others-e.g. (1) and (4)-such communica-
tion is always uncertain, and is the more likely the older the patient.
Popliteal vessels.-The artery traverses this space from above downwards,
appearing beneath the semi-membranosus, a little to the inner side of the middle
line, and then passing down in the centre of the space to the interval between the
gastrocnemii. Its line would be one drawn from the inner side of the hamstrings

FIG. 772.-DEEP VIEW OF THE POPLITEAL SPACE. (Hirschfeld and Leveillé.)
Adductor magnus
Vastus externus
-GREAT SCIATIC NERVE
Popliteal vein-
Popliteal artery-
INTERNAL POPLITEAL NERVE-
Vastus internus
Superior internal articular artery
Tendon of semi-membranosus
Inner head of gastrocnemius
Inferior internal articular artery-
Popliteal vein
Popliteus-
Short head of biceps
EXTERNAL POPLITEAL
NERVE
Long head of biceps, cut
Outer head of gastrocnemius
COMMUNICANS PERONEI
NERVE
Tendon of plantaris
Soleus
Gastrocnemius
External saphenous vein and nerve
to the centre of the lower part of the space. The artery bifurcates on the level
of a line corresponding in front to the tubercle of the tibia. It lies on the
popliteal surface of the femur, the posterior ligament, and the popliteus. It is the
second of these which usually prevents popliteal aneurism and abscess from making
their way into the joint. The popliteal vein, intimately adherent to the artery, lies
to the outer side above, but crosses to its inner side below. The walls of this vein
are thicker and denser than those of any other vein (Tillaux). The internal
popliteal nerve crosses the artery in the same direction as the vein by which it is
separated from the artery. This nerve is the direct continuation of the great
sciatic nerve (fig. 775).
The superior articular arteries course outwards and inwards immediately
above the condyles; the inferior ones lie just above the head of the fibula and

1228
SURGICAL AND TOPOGRAPHICAL ANATOMY
below the internal tuberosity of the tibia (fig. 775). The deep part of the
anastomotic artery runs in front of the tendon of the adductor magnus; the
superficial with the internal saphenous nerve.
The external saphenous vein perforates the roof of the popliteal space in its
lower part.
The popliteal glands are not to be felt unless enlarged.
FIG. 773.-THE POPLITEAL, THE POSTERIOR TIBIAL, AND THE PERONEAL ARTERIES.
Semi-tendinosus-
Semi-membranosus.
Sartorius.
Inferior internal articular artery-
Gracilis.
Inner head of gastrocnemius,,
hooked aside
Inferior sural artery_
Superior external articular artery
Biceps
Superior sural artery
Popliteal artery
Popliteus muscle
Inferior external articular artery
Soleus.
Tibialis posticus-
Soleus, turned back-
Gastrocnemius and soleus
Posterior tibial artery.
Peroneal artery
Flexor/longus digitorum
Flexor longus hallucis
FIBULA
Tibialis posticus-
Flexor longus digitorum-
Communicating artery
Anterior peroneal artery
Peroneus longus
Communicating artery
THE LEG
Bony landmarks. From the tubercle of the tibia descends the anterior border
or 'shin.' This soon becomes sharp, and 'continues so for its upper two-thirds;
in the lower third it disappears, to be overlaid by the extensor tendons. It is
curved somewhat outwards above, and inwards below. The inner border can also

THE LEG
1229
be felt from the inner tuberosity to the internal malleolus. Between these two
borders lies the internal surface, subcutaneous, save above, where it is covered by the
FIG. 774.-THE ANTERIOR TIBIAL ARTERY, DORSAL ARTERY OF THE FOOT, AND
ANTERIOR PERONEAL ARTERY, AND THEIR BRANCHES.
Superior internal articular artery
Inferior internal articular artery
Anterior tibial recurrent artery-
Superior external articular artery
-Inferior external articular artery
-Extensor longus digitorum
Anterior tibial artery.
Tibialis anticus muscle.
ANTERIOR TIBIAL NERVE-
Extensor longus hallucis
Extensor longus digitorum
turned back
Peroneus tertius
Anterior peroneal artery
Internal malleolar artery
External malleolar artery
Anterior annular ligament
Dorsalis pedis artery
Extensor brevis digitorum
Communicating branch.
Dorsalis hallucis artery-
-Peroneus brevis muscle
Extensor brevis digitorum, cut
External tarsal branch
Metatarsal branch
Dorsal interosseous artery
three tendons of insertion of the gracilis and semi-tendinosus, and, overlying them,
that of the sartorius. The tibia is narrowest and weakest at the junction of the

1230
SURGICAL AND TOPOGRAPHICAL ANATOMY
middle and lower thirds, the most common site of fracture. Behind the internal
malleolus, part of the groove for and the tendon of the tibialis posticus can be felt.
FIG. 775.-RELATIONS OF THE POPLITEAL ARTERY TO BONES AND MUSCLES.
Superior external articular artery
POPLITEAL NERVE
External lateral ligament
Inferior external articular artery
Superior internal articular artery
-Popliteal artery
-Posterior ligament of knee
-Azygos articular artery
Semi-membranosus
Muscular branch to soleus-
Soleus
Anterior tibial artery
Inferior internal articular artery
Muscular branch
Peroneus longus-
Peroneal artery-
BRANCH OF POSTERIOR TIBIAL-
NERVE TO FLEXOR LONGUS
HALLUCIS
Flexor longus hallucis.
Tibialis posticus
POSTERIOR TIBIAL NERVE
MUSCULAR BRANCH OF
POSTERIOR TIBIAL NERVE
TO FLEXOR LONGUS
DIGITORUM
Flexor longus digitorum
Posterior tibial artery
Cutaneous branch of peroneal artery-
Peroneus brevis-
Continuation of peroneal artery.
CALCANEUM
Tibialis posticus
Communicating branch
Internal annular ligament
Internal calcaneal artery
The head of the fibula can be felt distinctly, but the shaft soon becomes
buried amongst muscles till about three inches above the external malleolus,
where the bone expands into a large triangular subcutaneous surface. This lies
THE LEG
1231
between the peroneus tertius and the other two peronei. Behind the external
malleolus the tendons of the peronei longus and brevis descend to the foot in very
close relation to the bone. The shaft of the fibula is placed on a plane posterior to
that of the tibia, and curves backward in a direction reverse to that of the tibia.
Muscular prominences. The space between the tibia and fibula is mainly
occupied by the fleshy belly of the tibialis anticus; outside this, and much less
prominent, is the narrower extensor longus digitorum; outside this, again, are the
peronei longus and brevis. Lower down, in an interval between the tibialis and the
extensor of the toes, the extensor hallucis, here almost entirely tendinous, comes
to the surface. Behind, the prominence of the calf is mainly formed by the gastro-
cnemius. On the patient's rising on tiptoe, the tendo Achillis starts into relief from
about the middle of the leg. Of the two heads of the gastrocnemius, the inner is
seen to be the larger. On either side of the tendon, but more distinctly in the
outer side where it is less overlapped by the gastrocnemius, the soleus comes into
view.
FIG. 776.-SECTION OF THE RIGHT LEG IN THE UPPER THIRD. (Heath.)

Tibialis anticus
Extensor longus digitorum
Anterior tibial vessels and NERVE
Peroneus longus
Flexor longus hallucis-
Soleus with fibrous intersection
Gastrocnemius..
Tibialis posticus
Flexor longus digitorum
Internal saphenous vein
COMMUNICANS PERONEI NERVE
Tendon of plantaris
Peroneal vessels Posterior tibial vessels and NERVE
External saphenous vein and NERVE
Vessels. The saphena veins should be carefully traced, owing to the tendency
of these and their branches to become varicose. The internal, having passed from
the arch on the dorsum over the internal malleolus, runs up the inner side of the
leg, along the inner border of the tibia, to the back of the internal condyle, and then
upwards along the thigh, over the roof of Hunter's canal, to the saphenous opening
(page 1166 and figs. 710, 790), where it joins the femoral. The internal saphenous
nerve joins it below the knee, having been under the sartorius above this point (page
1215 and fig. 771). The external saphenous vein passes behind the external malleolus,
runs upwards over the middle of the calf, and joins the popliteal by perforating the
deep fascia in the lower part of the popliteal space. This vein is also accompanied by
a nerve of the same name throughout its course.
The popliteal artery bifurcates at the lower border of the popliteus, an inch
below the tubercle of the tibia. About three inches below the head of the fibula
the peroneal artery comes off from the posterior tibial (fig. 775).
The line of the posterior tibial is one drawn from the centre of the lower part
1232
SURGICAL AND TOPOGRAPHICAL ANATOMY
of the popliteal space to a point midway between the tip of the internal malleolus
and the inner edge of the calcaneum. In the lower third, the artery becomes
FIG. 777.-BRANCHES OF THE EXTERNAL POPLITEAL NERVE.

EXTERNAL POPLITEAL
NERVE
RECURRENT ARTICULAR
MUSCULO-CUTANEOUS
BRANCH TO PERONEUS
LONGUS
ANTERIOR TIBIAL
NERVE
BRANCH TO EXTENSOR
LONGUS DIGITORUM
BRANCH TO PERONEUS
BREVIS
Anterior tibial artery
Tibialis anticus
MUSCULO-CUTANEOUS-
MUSCULO-CUTANEOUS-
(OUTER DIVISION).
ANTERIOR TIBIAL
NERVE
MUSCULO-CUTANEOUS
(INNER DIVISION)
SHORT SAPHENOUS
COLLATERAL
BRANCHES OF EX-
TERNAL SAPHENOUS-
AND MUSCULO-
CUTANEOUS TO TOES
ANTERIOR TIBIAL
(OUTER DIVISION)
ITS DISTRIBUTION TO
EXTENSOR BREVIS
DIGITORUM
ANTERIOR TIBIAL
(INNER DIVISION)
COLLATERAL
BRANCHES OF
MUSCULO-CUTANEOUS
TO TOES
somewhat superficial, passing from beneath the calf muscles, together with the
tendons of the tibialis posticus and the flexor longus digitorum; and in a
THE LEG
1233
thin person it can be felt beating in the hollow on the inner side of the tendo
Achillis (fig. 775).
The line of the anterior tibial artery is one drawn from a point midway
between the outer tuberosity of the head of the fibula to one on the centre of the
ankle joint. This line corresponds to the outer border of the tibialis anticus and
the interval between it and the extensor longus digitorum (figs. 774 and 777).
This is shown when the first of these muscles is thrown into action.
The peroneal artery, given off from the posterior tibial about an inch below the
popliteus, or three inches below the head of the fibula, runs deeply along the inner
border of this bone, covered by the flexor longus hallucis. It gives off the anterior
peroneal to the front of the limb about an inch above the level of the ankle joint.
The nutrient artery of the tibia arises from the posterior tibial near its
commencement. It is the largest of all the nutrient arteries.
As a general rule, in amputation one inch below the head of the fibula, only
one main artery-the popliteal-is divided. In amputations two inches below
the head of the fibula, two main arteries-the anterior and posterior tibials-are
divided. In amputations three inches below the head, three main arteries-the two
tibials and the peroneal-are divided. (Holden.)
In an amputation through the middle of the leg, the anterior tibial artery would
be found cut on the interosseous membrane between the tibialis anticus and the
extensor longus hallucis, its nerve lying to its inner side. The posterior tibial
would be between the superficial and deep muscles at the back of the leg lying on
the tibialis posticus, its nerve being to the outer side. The peroneal would be close
to the fibula in the flexor longus hallucis.

THE ANKLE
Bony landmarks.-Malleoli.-The following are the differences between them.
The internal is the more prominent, shorter, and is placed more anteriorly than the
outer, being a little in front of the centre of the joint. The external descends lower
by a half to three-quarters of an inch, and thus securely locks in the joint on this
side; it is opposite to the centre of the ankle joint, being placed about half an inch
behind its fellow. The anterior margin of the lower end of the tibia can be traced
above the ankle joint, crossed by the tendons given below. Owing to the external
malleolus descending lower than the inner, in Symes and Pirogoff's amputation
the incision should run between the tip of the external malleolus and a point half
an inch below that of the internal one. When a fracture is set, or a dislocation
adjusted, the inner edge of the patella, the internal malleolus, and the inner side
of the great toe are useful landmarks and should be in the same vertical plane,
regard being paid at the same time to the corresponding points in the opposite limb.
(Holden.)
Tendons. (A) In front of ankle.-From without inwards are (1) The tibialis
anticus, the largest and most internal. This tendon appears in the lower third of
the leg, lying just under the deep fascia, close to the tibia; then, crossing over the
lower end of this and the ankle joint, passes over the inner side of the tarsus,
to be attached to the inner and lower part of the internal cuneiform and the
adjacent part of the first metatarsal. (2) The extensor proprius hallucis. This
tendon, concealed above, appears low down in a line just external to the last, and
then, crossing over the termination of the anterior tibial vessels and nerves (to
which its muscular part lies external), it descends along the inner part of the
dorsum to be attached to the base of the last phalanx of the great toe. (3) and (4)
The extensor longus digitorum and peroneus tertius enter a common sheath in the
anterior annular ligament. The former then divides into four tendons, which,
4 K
1234
SURGICAL AND TOPOGRAPHICAL ANATOMY
joined on the first phalanx by slips, three from the extensor brevis, and, a little later,
by slips from the lumbricales and interossei, are inserted into the second and last
to ostro o FIG. 778.-THE MUSCLES OF THE FRONT OF THE LEG.

gamni ed.
irtoje Ligamentum patella
oled
Gastrocnemius
Peroneus longuss hanoid
binow voedse
ede hus
Inidio poradnog
no gntyl gel
Soleus
eide no caio di ni
don Extensor proprius hallucis
Lesund ed
noitsinguts a Bogosid
Had Anior & ba
3nd
ebis semai edi has anlo
dail elizaggo odd
c)
ers
wol
Tibialis anticus
Peroneus tertius
Extensor longus digitorum
Peroneus tertius
Enided
hisy patiod burge
ohns T
Extensor brevis digitorum
Dorsal interossei.
od of
phalanges as in the fingers. The peroneus tertius is inserted into the upper
surface of the base of the fifth metatarsal bone.

THE ANKLE
1235
(B) Behind. The tendo Achillis, the thickest of all tendons, begins near the
middle of the leg, in the junction of the tendons of the gastrocnemii and soleus.
Very broad at its commencement, it gradually narrows and becomes very thick.
About an inch and a half from the heel, or about the level of the internal
malleolus, is its narrowest point. After this it again expands slightly, to be
attached to the middle of the back part of the calcaneum. The long tendon of the
FIG. 779.-TRANSVERSE SECTION THROUGH THE LOWER THIRD OF THE LEFT LEG,
IMMEDIATELY ABOVE THE ANKLE JOINT. (Braune.)

Tibialis anticus
Extensor longus digitorum
Extensor proprius hallucis
Peroneus longus
Peroneus brevis
Flexor longus hallucis
EXTERNAL CUTANEOUS NERVE
Tibialis posticus
Flexor longus digitorum
plantaris runs along its inner side, to blend with it or to be attached to the calcaneum.
On either side of the tendo Achillis are well-marked furrows below. Along the
inner, the tendon of the tibialis posticus and the posterior tibial vessels and nerve
FIG. 780.-RELATIONS OF PARTS BEHIND THE INNER MALLEOLUS. (Heath.)
(The tendon of the flexor longus hallucis is too deeply placed to be shown in this view.)
Tendo Achillis
Tibialis posticus
Flexor longus digitorum
Tibialis posticus
Tibialis anticus
-Posterior tibial artery
POSTERIOR TIBIAL NERVE
Flexor longus digitorum
come nearer the surface. Along the outer, the external saphenous vein (more
superficially) ascends from behind the external malleolus.
(C) On the inner side.-The tendon of the tibialis posticus, which has previously
crossed from the interspace between the bones of the leg to the inner side, lies
behind the inner edge of the tibia above the internal malleolus, being here under
the flexor longus digitorum, the two tendons here becoming superficial on the inner
4 K 2
1236
SURGICAL AND TOPOGRAPHICAL ANATOMY
side of the tendo Achillis. It then passes forwards close below the sustentaculum tali
and the head of the astragalus, and then very close to the inferior calcaneo-scaphoid
FIG. 781.-THE DEEP MUSCLES OF THE BACK OF THE LEG.

Plantaris
Outer head of gastrocnemius
Biceps
Inner head of gastrocnemius
Tendon of semi-membranosus
Popliteus
Tibialis posticus
Peroneus longus
Flexor longus digitorum
.0000
Flexor longus hallucis
Peroneus brevis.
Tibialis posticus
Tendo Achillis
ligament (vide infra), and so to its insertion, by numerous slips, into the tarsus and
metatarsus, especially the tubercle of the scaphoid. The tendon of the flexor
THE ANKLE
1237
longus hallucis cannot be felt. Having parted internally from the fibula, it crosses
the lower end of the tibia in a separate furrow, then grooves the back of the
astragalus, and passes under the sustentaculum tali on its way to its insertion. The
arrangement of the structures at the inner ankle from above downwards, and from
within onwards, is as follows (fig. 780):-tibialis posticus, flexor longus digitorum,
companion vein, posterior tibial artery, companion vein, posterior tibial nerve,
flexor longus hallucis.
(D) Tendons at outer ankle.-The tendons of the two peronei, which arise from
the fibula between the extensor longus digitorum and flexor longus hallucis, pass
behind the external malleolus, the brevis being nearer to the bone (fig. 781). They
then pass forwards over the outer surface of the calcaneum, separated by the peroneal
tubercle when present, and diverge. The brevis, the upper one, passes to the pro-
jection at the base of the fifth metatarsal; the longus, lying below the brevis on
the calcaneum, winds round the outer border of the foot, grooving the outer border
and under surface of the cuboid. Finally, crossing the sole obliquely forwards and
inwards, it is attached to the adjacent parts of the internal cuneiform and the back
part and under surface of the first metatarsal. While in connection with the
cuboid, this tendon is covered in by a sheath from the long plantar ligament, and
often contains a sesamoid bone.
Annular ligaments and synovial membranes of tendons.-These strap-like
bands of deep fascia, which serve to keep the above tendons in position, are three in
number, viz. :-
(A) External.-This extends from the tip of the external malleolus to the outer
surface of the calcaneum. It keeps the two peronei in place, and surrounds them
behind the fibula in one sheath with a single synovial sac, which extends upwards
into the leg for an inch and a half, and sends two processes into the two sheaths
in which the tendons lie on the calcaneum. Farther on, while in relation with the
cuboid, the peroneus longus has a second synovial sheath.
(B) Internal. This crosses from the internal malleolus to the inner surface of the
calcaneum. Beneath it are the following canals: (1) For the tibialis posticus. This
tendon-sheath is lined by a synovial membrane extending from a point an inch and
a half above the malleolus to the scaphoid. (2) For the flexor longus digitorum.
The synovial sheath of this tendon is separate from that of the closely contiguous
tibialis posticus. It extends upwards into the leg about as high as the sheath just
given. It reaches down into the sole of the foot; but where the tendon subdivides to
enter the thecæ, each of these is lined by a separate synovial sheath. Next comes
(3) a wide space for the posterior tibial vessels and nerve; and lastly, (4) a canal,
like the other two, with a separate synovial sheath, for the tendon of the flexor
longus hallucis.
(C) Anterior annular ligament. This is a double structure. (1) Upper, above
the level of the ankle joint, and tying the tendons down to the lower third of the
leg, it passes transversely between the anterior crest of the tibia and fibula. Here
is one sheath only, with a synovial membrane for the tibialis posticus. (2) Lower,
over the ankle joint. This band is arranged like the letter, placed thus. It
is attached by its root to the calcaneum, and by its bifurcations to the internal
malleolus and the fascia of the sole. This arrangement of the branches of this
ligament is not constant. In this, the lower annular ligament, there are usually
three sheaths with separate synovial membranes-the innermost (the strongest in
each) for the tibialis anticus, the next for the extensor proprius hallucis, and the
third common to the extensor communis and peroneus tertius.
Points in tenotomy and guides to the tendons.-The tendo Achillis should be
divided about an inch and a half above its insertion, its narrowest point, which is
about on a level with the internal malleolus. The knife should be introduced on the
inner side and close to the tendon, so as to avoid the posterior tibial artery (fig. 775.)

1238
SURGICAL AND TOPOGRAPHICAL ANATOMY
The tibialis anticus is often cut about an inch above its insertion into the
internal cuneiform, a point which is below the level of its synovial sheath. The
tendon has here the dorsalis pedis on its outer side, but separated by the tendon of
the extensor proprius hallucis. The knife is introduced on this side.
The tibialis posticus.-The usual rule for dividing this tendon is to take a spot
two inches above the internal malleolus, and as accurately as possible midway
between the anterior and internal borders of the leg. This point will give the
inner margin of the tibia, in close apposition to which the tendon is lying, and is a
point at which the tendon is rather farther from the artery than it is below, and is
also above the commencement of its synovial sheath. A sharp-pointed knife is
used first to open the sheath freely, and then a blunt-pointed one to divide the
tendon. The flexor longus digitorum is usually cut at the same time.
Owing to the great difficulty in making sure of dividing the tibialis posticus
tendon at this spot, and the risk of cutting the posterior tibial artery (fig. 775), it
has been advised of late years (Parker) to divide this tendon together with that
of the anticus simultaneously by an incision a little below and anterior to the tip
of the internal malleolus. Other guides are the position of the astragalo-scaphoid
joint, and, where the deformity is of some standing, the crease which denotes the
inversion of the foot. The position of the two tibial arteries should be noted, and
also the lines along which the tendons are converging-the one across the lower end
of the tibia, the other from behind the tibia and below the sustentaculum tali to
the line of the scaphoid and internal cuneiform. Mr. R. W. Parker has named
this operation syndesmotomy, as he rightly considers that the astragalo-scaphoid
ligaments require division at the same time.
Peronei. The peronei longus and brevis may be divided two inches above the
external malleolus, so as to be above the level of their synovial sheath. The knife
should be inserted very close to the bone, so as to pass between the fibula and the
tendons. Division below the external malleolus is somewhat easier, but as this
opens their synovial sheath or sheaths (vide supra, page 1237), it requires scrupulous
care as to cleanliness.
THE FOOT

Bony landmarks. The following are of the greatest practical importance owing
to the operations on which they bear.
(A) Along the inner aspect of the foot are the following:-
(1) Internal tuberosity of the calcaneum; (2) internal malleolus; (3) one full
inch below the malleolus, the sustentaculum tali; (4) about an inch in front of the
internal malleolus, and a little lower, is the tubercle of the scaphoid, the gap
between it and the sustentaculum being filled by the calcaneo-scaphoid ligament
and the tendon of the tibialis posticus, in which there is often a sesamoid bone;
(5) the internal cuneiform; (6) the base of the first metatarsal; and (7) the head
of the same bone, with its sesamoid bones below. (Holden.)
(B) Along the outer aspect are (1) The outer tuberosity of the calcaneum;
(2) the external malleolus; (3) the peroneal tubercle of the calcaneum (when
present), one inch below the malleolus, with the long peroneal tendon below it,
and the short one above; (4) the projection of the anterior end of the calcaneum, and
the calcaneo-cuboid joint, midway between the tip of the external malleolus and
the base of the fifth metatarsal bone; (5) the base of the fifth metatarsal bone;
(6) the head of this bone.
Levels of joints and lines of operations.-In Syme's amputation through the
ankle joint, the incision starts (say in the case of the left foot) from the tip of the
external malleolus, and is then carried, pointing a little backwards towards the heel,
across the sole to a point half an inch below the internal malleolus.

THE FOOT ALL
1239
LOTUE
In Pirogoff's amputation the incision begins and ends at the same points, but is
carried straight across the sole. In each amputation the bones of the above incision
FIG. 782.-ARTICULATIONS OF THE FOOT, DORSAL ASPECT. (Bellamy.)
Sini

LINE OF CHOPART
TUBERCLE OF SCAPHOID-
--TUBERCLE OF FIFTH METATARSAL
LINE OF HEY.-
are joined by one going straight across the ankle joint, which lies about half an
inch above the tip of the internal malleolus.
In Chopart's medio-tarsal amputation (fig. 782), which passes between the
astragalus and the scaphoid on the inner side, and the calcaneum and the cuboid
on the outer, the line of the joints to be opened would be one drawn across
FIG. 783.-VERTICAL SECTION THROUGH THE CUNEIFORM AND CUBOID BONES.
(One-half.)

Dorsalis pedis vessels and NERVE
Extensor proprius hallucis
INTERNAL CUNEIFORM
Tibialis anticus
MIDDLE CUNEIFORM
EXTERNAL CUNEIFORM
Extensor brevis digitorum
Dorsal aponeurosis
CUBOID
Peroneus tertius
Abductor hallucis
Internal plantar vessels and NERVE
Abductor hallucis
Flexor longus hallucis
Plantar fascia
Flexor longus digitorum
Abductor minimi digiti
External plantar vessels and NERVE
Tendon of peroneus longus
Flexor brevis digitorum
the dorsum from a point just behind the tuberosity of the scaphoid to a point
corresponding to the calcaneo-cuboid joint, just midway between the tip of the
external malleolus and the base of the fifth metatarsal bone.
1240
SURGICAL AND TOPOGRAPHICAL ANATOMY
In Lisfranc's, or Hey's, or the tarso-metatarsal amputation, the bases of the
fifth and first metatarsals must be defined. The first of these can always be
detected, even in a stout or swollen foot, on the inner side; the joint between the
internal cuneiform and the first metatarsal bone lies an inch and a half in front
of the scaphoid tubercle. In opening the joint between the second metatarsal and
the middle cuneiform, its position (the base of the former bone projecting upwards on
FIG. 784.-SUPERFICIAL NERVES IN THE SOLE OF THE FOOT. (Ellis.)

Abductor hallucis.
Abductor minimi digiti
Flexor brevis digitorum.
INTERNAL PLANTAR
NERVE
Internal plantar artery-
External plantar artery
EXTERNAL PLANTAR
NERVE
Jagod
BRANCH OF IN-
TERNAL PLANTAR
NERVE TO INNER
SIDE OF HALLUX
DIGITAL COLLATERAL
BRANCHES OF
EXTERNAL
PLANTAR
DIGITAL COLLATERAL
BRANCHES OF
INTERNAL PLANTAR
to a level one-third or one-fourth of an inch above the others), and the way in which
it is locked in between its fellows and the cuneiform bones, must be remembered.
In marking out the flaps for the amputation of the great toes, the large size of
the head of the first metatarsal, and the importance of leaving this so as not to
diminish its supporting power and the treading width of the foot, and thus of
marking out flaps sufficiently long and large, must be borne in mind. In amputation
of the other toes, the line of their metatarso-phalangeal joints lies a full inch above
the web.

THE FOOT
1241
Bursæ and synovial membranes.-The synovial sheath of the extensor proprius
hallucis extends from the front of the ankle, over the instep, as far as the metatarsal
bone of the great toe. There is generally a bursa over the instep, above, or it may be
below, the tendon. There is often an irregular bursa between the tendons of the
extensor longus digitorum and the projecting end of the astragalus over which
the tendons play. There is much friction here. It is well to be aware that this
bursa sometimes communicates with the joint of the head of the astragalus (Holden).
There is a deep synovial bursa between the tendo Achillis and the calcaneum.
Numerous other bursæ may appear over any of the bony points in the foot, especially
when they are rendered over-prominent by morbid conditions.
FIG. 785.-PLANTAR ARTERIES (DEEP).
(From a dissection in the Hunterian Museum.)
Internal calcanean
branch of posterior tibial
Posterior tibial artery
Abductor hallucis, cut-
Internal plantar artery
Inner head of flexor
accessorius
OS CALCIS
Cutaneous and
anastomotic branches
of external plantar
-Outer head of flexor
accessorius
Flexor longus hallucis
External plantar artery
Adductor hallucis
Flexor brevis hallucis
Princeps hallucis artery
Flexor tendons,
cut short
Collateral digital branch
of princeps hallucis to
inner side of great toe
Abnormal muscular slip
Muscular branch
-Cutaneous branch
Collateral digital artery
to outer side of little toe
Second digital artery
Third digital artery
Fourth digital artery
Synovial membranes. In addition to that of the ankle joint, there are six
synovial membranes in the tarsus, viz. :-(1) Posterior calcaneo-astragaloid, peculiar
to these bones; (2) anterior calcaneo-astragaloid, common to these bones and the
scaphoid; (3) between the calcaneum and the cuboid; (4) between the cuboid and
the outer two metatarsals; (5) between the internal cuneiform and the first meta-
tarsal; (6) a complicated and extensive one, which branches out between the
scaphoid and cuneiform bones; between the cuneiforms; between the external
cuneiform and the cuboid; between the middle and outer cuneiform and the second
1242
SURGICAL AND TOPOGRAPHICAL ANATOMY
and third metatarsal bones; and between the second and third, and the third and
fourth metatarsal bones (fig. 258).
Dorsal artery. The line of this is from the centre of the ankle joint to the
upper part of the first interosseous space. On its inner side is the tendon of the
extensor proprius hallucis; on its outer, the innermost tendon of the extensor longus
digitorum. It is crossed by the innermost tendon of the extensor brevis. The
origin of this muscle should be marked on the outer and fore part of the calcaneum.
Cutaneous nerves (figs. 777, 791). The sites of these, numerous on the dorsum
of the foot, are as follows:-The musculo-cutaneous nerve, having perforated the
fascia in the lower third of the leg, divides into two chief branches, inner and outer,
which supply all the toes save the outer part of the little, and the adjacent sides
of the first and second. The anterior tibial becomes cutaneous in the first space,
and is distributed to the contiguous sides of the above-mentioned toes. The
external saphenous nerve runs with its vein below the malleolus, and supplies all
the outer border of the foot and the outer side of the little toe. The internal
saphenous nerve, coursing with its vein in front of the internal malleolus, supplies
the inner border of the foot as far as the middle of the instep.
Plantar arteries.-The line of the internal would be one drawn from the
bifurcation of the posterior tibial, or about midway between the tip of the internal
malleolus and the inner border of the heel, to the middle of the plantar surface of
the great toe. The course of the external plantar runs in a line drawn from the
bifurcation, first obliquely across the foot to a point a little internal to the inner
side of the base of the fifth metatarsal, and thence obliquely across the foot till it
reaches the first space and joins with a communicating branch from the dorsal
artery. It thus crosses the foot twice. In the first part it is more superficial, in
the second very deep; it here forms the plantar arch, and is only separated from
the bases of the metatarsals by the interossei.
FIG. 786.-LONGITUDINAL SECTION OF FOOT. (One-third.) (Braune.)
Tendo Achillis
ASTRAGALUS
Posterior tibial vessels
and NERVE

SCAPHOID
INTERNAL CUNEIFORM
Extensor proprius hallucis
Flexor longus hallucis
Flexor brevis hallucis
Lumbricalis
CALCANEUM
Adductor minimi digiti
External plantar vessels and NERVE
Accessorius
Flexor brevis digitorum Flexor communis digitorum
INTERNAL PLANTAR NERVE
ARCHES OF THE FOOT
These are two-the longitudinal and the transverse.
(A) Longitudinal arch (fig. 786). This is by far the most important. Extent:
From the heel to the heads of the metatarsal bones. The toes do not add much to

ARCHES OF THE FOOT
1243
the strength and elasticity of the foot (Humphry). They enlarge its area and adapt
it to inequalities of the ground, are useful in climbing, and in giving an impulse to
and al
FIG. 787.-THE ARCH IN THE ORDINARY POSITION OF STANDING. (Ellis of Gloucester.)

Muscles going to form the
tendo Achillis
Tibialis posticus
Flexor longus hallucis
-Tibialis anticus
FIG. 788.-THIS SHOWS THE EFFECT OF MUSCULAR ACTION IN THROWING UP THE ARCH.
(Ellis of Gloucester.)

Tendo Achillis
Tibialis posticus
-Flexor longus hallucis
the step before the foot is taken from the ground, in the third stage of walking.
Two pillars.-Professor Humphry lays stress on the important differences between
these two: (1) Posterior pillar: This consists of the calcaneum and hinder part of the
1244
SURGICAL AND TOPOGRAPHICAL ANATOMY
astragalus, viz. only two bones in order to secure solidity, and to enable the calf-
muscles to act directly upon the heel, without any of that loss of power which
would be brought about by many moving joint-surfaces. (2) Anterior pillar:
Here there are many bones and joints to provide (a) elastic springiness, and
(b) width. This anterior pillar may again be divided into two: (a) An inner pillar,
very elastic, consisting of the astragalus, scaphoid, three cuneiforms, and three
inner metatarsals. (b) An outer, formed by the cuboids and two outer metatarsals.
This is stronger and less elastic, and tends to buttress up the inner pillar. Key-
stone: This is represented by the summit of the trochlear surface of the astragalus.
FIG. 789.-FOURTH LAYER OF THE MUSCLES OF THE SOLE.

Peroneus longus-
Plantar interossei
Dorsal interosse
It differs from the keystones in ordinary arches in the following important
particulars (Humphry): (a) in not being wedge-shaped; (b) in not being so
placed as to support and receive support from the two halves of the arch in front
the astragalus does fulfil this condition by fitting into the scaphoid; behind, it
overlaps the calcaneum without at all supporting it; (c) this arch and the support
of its keystone largely depend on ligaments and tendons; (d) it is a mobile keystone:
to give it chances of shifting its pressure, and so obtaining rest, its equilibrium is
not always maintained in one position.
(B) Transverse arch (fig. 783).-This is best marked about the centre of the foot,

ARCHES OF THE FOOT
1245
FIG. 790.-THE SUPERFICIAL VEINS AND LYMPHATICS OF THE LOWER LIMB.
Superficial epigastric vein,
Lymphatics from penis
and scrotum
Common femoral vein
Superficial femoral
lymphatic glands
Superficial external pudic
vein
Superficial lymphatics
from lateral wall of
abdomen
Superficial lymphatics
from lower and anterior
walls of abdomen
Superficial inguinal
lymphatic glands
-Superficial circumflex
iliac vein
Internal femoral cutaneous
vein
External femoral
cutaneous vein
Long saphenous vein
INTERNAL MALLEOLUS
Dorsal venous arch
1246
SURGICAL AND TOPOGRAPHICAL ANATOMY
at the instep, along the tarso-metatarsal joints. This, as well as the longitudinal
arch, yields in walking, and so gives elasticity and spring.
Uses of the arches.-(1) They give combined elasticity and strength to the
tread. Thus they give firmness, free quickness, and dignity, both in standing and
walking, instead of what we see in their absence, viz. the lameness of an artificial
limb, and the shuffling or hobbling which goes with tight boots, deformed toes,
flat-foot, bunions, corns, etc.; (2) they protect the plantar vessels, nerves, and
muscles; (3) they add to man's height; (4) they make his gait a perfect combina-
tion of plantigrade and digitigrade, as is seen in man's walking, when he uses first
the heel, then all the foot, and then the toes. (Humphry.)
FIG. 791.-DISTRIBUTION OF CUTANEOUS NERVES ON THE POSTERIOR AND ANTERIOR
ASPECTS OF THE INFERIOR EXTREMITY.


LAST
THORACIC
ILIO-
HYPOGASTRIC
EXTERNAL
CUTANEOUS
POSTERIOR
BRANCHES
OF LUMBAR
NERVES
POSTERIOR
BRANCHES
OF SACRAL
NERVES
PERFORATING
ILIO-
INGUINAL
EXTERNAL
CUTANEOUS
GENITO-
CRURAL
CUTANEOUS
OF FOURTH
SACRAL
TWIG FROM
INTERNAL
LONG
CUTANEOUS
PUDENDAL
BRANCHES OF
SMALL
SCIATIC
INTERNAL
OBTURATOR
CUTANEOUS
SMALL
SCIATIC
EXTERNAL
CUTANEOUS
COMMUNICANS
FIBULARIS
POSTERIOR
BRANCH OF
INTERNAL
CUTANEOUS
COMMUNI-
CANS
TIBIALIS
PATELLAR
BRANCH
OF LONG
SAPHENOUS-
LONG
SAPHENOUS
SHORT
SAPHENOUS-
TWIGS FROM
LONG
SAPHENOUS
INTERNAL
CALCANEAN
ANTERIOR
TIBIAL
MIDDLE
CUTANEOUS
CUTANEOUS
BRANCH OF
EXTERNAL
POPLITEAL
MUSCULO-
CUTANEOUS
SHORT
SAPHENOUS
Maintenance of the arch. (1) Plantar fascia. This is (a) a binding tie
between the pillars of the longitudinal arch; (b) it protects the structures beneath;
(c) it is a self-regulating ligament and protection. Thus, having a quantity of
muscular tissue attached to its upper and back part, it constantly responds by the
contraction of this, to the amount of any pressure made upon the foot. (2) Calcaneo-
scaphoid ligament.-This is a thick plate of fibrous tissue, partly elastic, attached to
the under surface of the calcaneum, sustentaculum tali, and scaphoid. It is thickest
at its inner side, where it blends with the anterior part of the deltoid ligament, and
where the tibialis posticus passes into the sole, giving much support to the head
of the astragalus, and assisting the power and spring of this ligament (vide infra).

ARCHES OF THE FOOT
1247
(3) Calcaneo-cuboid ligaments. (a) Long; (b) short.-These ligaments are the
main support of the outer, firm, and less elastic part of the longitudinal arch.
(4) Tibialis posticus. The reason of this muscle having so many insertions
below is to brace together the tarsal bones, and to prevent their separation when, in
treading, the elastic anterior pillar tends to widen out. Of these numerous offsets,
that to the scaphoid is the most important. Thus it strengthens the calcaneo-
scaphoid ligament by blending with it, and thus supports the arch at a trying
time. By coming into action when the heel is raised (fig. 788), this tendon helps the
calcaneo-scaphoid ligament to support the head of the astragalus, and to maintain
the arch of the foot when the weight of the body is thrown forward on to the
instep. In other words, the tibialis posticus comes into play just when the heaviest
of its duties is devolving upon this ligament, viz. when the heel is being raised,
and the body-weight is being thrown over the instep on to the opposite foot.
(5) Peroneus longus. This raises the outer pillar, and steadies the outer side of the
arch. Further, by its strong process attached to the first metatarsal bone (fig. 789),
it keeps the great toe strapped down firmly against the ground; thus, keeping
down the anterior pillar of the longitudinal arch, it aids the firmness of the tread
(Humphry). (6) Tibialis anticus. This braces up the keystone of the arch. Thus,
by keeping up the internal cuneiform, it maintains the scaphoid, and so indirectly
the astragalus, in situ.
Fig. 790 is introduced here to remind the student of the arrangement of the
superficial lymphatics of the lower extremity.
Fig. 791 shows the distribution of the superficial nerves on both aspects of
the limb.
THE REGIONS OF THE ABDOMEN
BY WILLIAM ANDERSON, F.R.C.S.
As the plan of segmenting the ventral surface of the abdomen by means of two
horizontal, and two vertical or nearly vertical lines, has survived the test of time,
it might be assumed that it is a resource of some practical value to the physician.
and surgeon. It is, however, a curious fact that, although the nine historical
regions of the abdomen have been universally accepted in British and continental
schools for at least forty years, and may be traced back to a very much more
remote period, no attempt has ever been made to secure uniformity in the plan
of their delimitation, but almost every anatomical writer has elected to follow a
system of his own, and, consequently, there are at the present moment at least
fourteen different schemes in our recognised text-books. There is little doubt that
it were better to abandon altogether the pretence of a regional subdivision than to
employ terms which have no scientific meaning, but it may be hoped that some
accord will soon be arrived at.
On analysing the various systems it will be seen that the upper horizontal
line may be drawn either (1) between the ninth costal cartilages of the two
sides the precise part of the cartilage, which forms about two inches of the
border of the thorax, being usually left undefined (Gray, Todd, Turner, Holden,
Heath, Shield, Tillaux); (2) between the tenth costal cartilages (Macalister,
Aitken, Joessel); between the lowest points of the thoracic border, usually the
eleventh costal cartilage (Quain, Cunningham, Henle); or (3) on a level with the
tips of the twelfth ribs (Hyrtl, Rüdinger). The lower horizontal line may be drawn

1248
SURGICAL AND TOPOGRAPHICAL ANATOMY
(1) either at the level of the highest point of the iliac crest (Quain, Gray, Turner,
Cunningham, Henle, Bellamy, and others); or (2) between the anterior superior
iliac spines (Todd, Holden, Heath, Macalister, Shield, Tillaux, Hyrtl, Rüdinger, and
Joessel). The longitudinal line on each side may run upwards (1) from the middle
of Poupart's ligament (Quain, Gray, Turner, Heath, Tillaux); (2) from the inner
part of the ligament (Todd, Rüdinger); (3) from the pubic spine (Aitken, Mac-
alister); or (4) from the anterior superior iliac spine (Hyrtl); (5) from the ilio-
pectineal eminence (Joessel). It may be directed perpendicularly upwards without
reference to any terminal point (Quain, Cunningham, Tillaux); or it may be drawn
to a fixed, but often rather indefinite, locality above, as the seventh costal cartilage
(Heath, Bellamy); the bony extremity of the sixth or seventh rib (Rüdinger);
'the extremity of the seventh or eighth rib' (Todd); the eighth costal cartilage,'
without reference to the particular part of the structure (Gray, Holden, Macalister,
Shield); to the ninth or tenth rib' (Henle); to the sterno-clavicular joint (Hyrtl);
to the acromio-clavicular joint (Aitken, etc.); or may stop short at the superior
horizontal line, the upper region being subdivided by the costal border (Joessel).

6
6
Setting aside the impracticability of some of these indications, it is obvious that
the variations between the different systems are really important. For example,
in the scheme most in vogue, that adopted in Quain's Anatomy,' the umbilicus
lies at the lowest limit of the umbilical region, or even outside it altogether-never
in the middle as the diagrams depict-and the height of the area seldom exceeds
two inches, and is often less; in Gray's Anatomy' the elevation of the upper
horizontal line to the ninth costal cartilage adds an inch or two above; and in
Macalister and Tillaux the depression of the lower horizontal line to the iliac
spines lends an increase of about three inches in the other direction, and the
umbilicus now falls in the centre of the area from which it takes its name.
Again, in most of the systems the outline of the region is rectangular, or nearly
so; but in Aitken it widens above towards the points of the shoulders, and in
Hyrtl it widens below towards the anterior inferior iliac spines. Equally serious
discrepancies exist in all of the other regions.
1
Whatever system be adopted, it is necessary that the boundary lines' should
be converted into planes carried through the whole depth of the abdomen, and
defined on the dorsal as well as on the ventral surface of the trunk, and that the
structures cut through by these planes should be noted, as well as those comprised
within the regions which they separate. It should, of course, be recognised that
the relations so defined can only be approximate, on account of the wide range of
physiological variation in the position of the abdominal contents; but this being
understood, a regional type would be of material service in medical education.
Could we cast off tradition without loss, it would, perhaps, be more simple,
and more useful, to divide the cavity into superior and inferior segments by a
single horizontal plane at the level of the umbilicus (or of the highest point of
the iliac crest), and then to subdivide each segment into three by two vertical lines
drawn as described, from the middle of Poupart's ligament. The regions might
then be called right, left, and middle superior, and right, left, and middle inferior;
but such a change would have the great disadvantage of making the older
references unintelligible.
If we retain the subdivision into nine segments, it remains only to consider
the method of delimitation. Firstly, for the higher plane, the most suitable level
appears to be that adopted in Quain's Anatomy,' the lowest point of the cartila-
ginous border of the thorax (usually the eleventh costal cartilage). This plane
passes through the second lumbar vertebra posteriorly, and lies about two inches
above the umbilicus in front. It cuts through the stomach, the transverse colon,
the ascending and descending colon, the duodenum (lower curvature) and small
intestine, and the kidneys. For the lower horizontal plane we have the choice of

THE REGIONS OF THE ABDOMEN
1249
two levels-that of the highest point of the iliac crest, corresponding to the lower
part of the third lumbar vertebra, and that of the anterior superior iliac spine, which
lies about an inch below the level of the sacral promontory.
RIGHT
The Abdominal Viscera regionally arranged.
Hypochondriac
Liver: portion of right lobe
(gall bladder, usually
cut by longitudinal line).
Kidney: upper and outer
part.
Colon: hepatic flexure
and part of ascending
colon.
Lumbar
Longitudinal plane along outer border of rectus-
MIDDLE
Epigastric
Liver: quadrate, caudate,
Spigelian, and greater
part of left lobes (gall
bladder usually cut by
longitudinal line).
Pancreas: head and body.
Spleen: upper and inner
part.
Kidneys: upper and inner
parts, with pelvis renalis.
Suprarenal bodies.
Stomach:
middle and
pyloric regions, cardiac
and pyloric orifices.
Duodenum: first and se-
cond portions and termi-
nation of third portion.
Small intestine: trans-
verse colon, variable
portion.
Longitudinal plane along outer border of rectus-
LEFT
Hypochondriac
Liver: portion of left lobe.
Spleen: lower and outer
part.
Pancreas: tail.
Kidneys: upper and outer
part.
Stomach: great cul-de-sac.
Colon: splenic flexure.

Upper horizontal plane at level of lowest point of costal border-
Kidney: lower and outer
part.
Ascending colon and por-
tion or whole of cæcum.
Small intestine: chiefly
eum.
Umbilical
Kidneys: lower and inner
portions with ureters.
Duodenum: lower flexure
and part of third portion.
Jejunum and ileum.
Transverse colon:
tion.
por-
Sigmoid flexure and com-
mencement of rectum.
Lumbar
Kidney: lower and outer
part.
Small intestine: chiefly
jejunum.
Descending colon and por-
tion of sigmoid flexure.
-Lower horizontal plane at level of anterior superior iliac spines carried into true pelvis-
Inguinal
Cacum: lower portion,
Small intestines.
occasionally.
Inguinal canal.
Hypogastric
Small intestines.
Sigmoid flexure and rec-
tum (portion).
Cacum: occasionally.
Ureters.
Bladder: in children, and
if distended in adults.
Fundus uteri and append-
ages.
Inguinal
Small intestine.
Sigmoid flexure : portion.
Inguinal canal.
The objection to the plane of the highest point of the iliac crest is that it
frequently excludes the umbilicus from the umbilical region, and reduces the middle
zone (lumbar and umbilical regions) to a very narrow segment of the abdomen. On
the other hand, the lower plane, that of the anterior iliac spines, passes into the
true pelvis and leaves a large portion of the iliac fossæ in the lumbar regions, and
it confines the lower lateral regions within a very restricted area.
On the whole,
however, it seems the more convenient, as it leaves the umbilicus nearly in the
4 L
1250
SURGICAL AND TOPOGRAPHICAL ANATOMY
middle of the umbilical region, and if the longitudinal plane corresponding to the
outer border of the rectus be adopted, the inguinal canal will be left intact in
the 'inguinal' region. This lower plane, if carried horizontally backwards from the
symphysis into the pelvis, cuts the small intestine, the cæcum or lower part of the
ascending colon, the sigmoid flexure, the upper end of the rectum, the fundus uteri,
the ovaries and Fallopian tubes, and the distended bladder.
For the longitudinal plane on each side, that corresponding to the vertical line
of Quain, running upwards parallel to the mesial line from the middle of Poupart's
ligament, is already familiar to the greater number of observers; but it has the
disadvantage of making the mesial regions very large in proportion to the lateral
regions, the upper lateral regions being still further reduced in women owing to
the narrowness of the chest when compared with the width of the pelvis. As an
alternative, the outer border of the rectus would be preferable, as it is easily
localised by the lateral infracostal furrow above, and by the pubic spine below;
and while reducing the width of the middle zone without interfering materially
with existing indications of contents, it leaves an inguinal region that includes the
whole of the inguinal canal. Each plane cuts the kidney, transverse colon, and
small intestine; the right plane cuts also the gall bladder, and sometimes the
cæcum; the left cuts the sigmoid flexure, the stomach (great cul-de-sac), the pan-
creas, and the spleen. The table on the preceding page will show the contents of
the regions adjusted according to this scheme.
NOTE.

Ligamentum nucha :-This structure has been referred to on page 206. As seen in
the horse, elephant, ox, and other quadrupeds, it is a great and important elastic ligament.
In man it is but a slender band of elastic and white fibres extending from the spine of the
seventh cervical vertebra, where it is continuous with the supraspinous ligament, to the
external occipital protuberance and occipital crest. The Trapezii muscles take origin
from it.
A thin tendinous layer connects its deep surface with the tips of the spinous processes
of the cervical vertebræ, thus forming a septum between the muscles of the neck.

INDEX
[The principal authority for the derivations of the anatomical terms given in this
Index is Hyrtl's Onomatologia Anatomica,' Vienna, 1880.]
6
ABD
ABDOMEN [from abdo I hide; or, more prob-
=
ably from adeps fat: as if for adipo-
men fat belly of swine], the, 994
contents seen on opening the, 995
lymphatics of, parietal, 700
visceral, 702
lymph glands of, parietal, 700
regions of, 1247
visceral, 702
surgical anatomy of, 1141
veins of, 669
Abdominal aorta, 584; branches, parietal
586, visceral 588; variations, 585
muscles, 425-436
nerves of vagus, 819
parietes, structure of, 425; topography of
vessels and nerves in, 1144
portion of ureter, 1052
ring, external, 430, 1142, 1159
effect of position on, 1159
internal, 436, 1144, 1161
viscera, 989; regionally arranged, 1249
lymphatics of, 702
=
Abducent [ab= from; duco I lead], or sixth
cranial, nerve, 805
Abduction, 189
Abductor hallucis [hallux=great toe] muscle,
401; variations, 401
minimi digiti muscle of hand, 363
of foot, 402; variations, 403
ossis metatarsi quinti muscle, 487
pollicis [pollex = thumb] muscle, 358;
variations, 360
Abnormal muscles, 487-490
Accelerator urinæ [from its action in hastening
the expulsion of the urine] or bulbo-
cavernosus muscle, 1072
Accessorius [accedere to be added to] ad ilio-
costalem (vel sacro-lumbalem), 441
Accessory artery, pudic, 605
band of atlanto-axoidean capsules, 196
cartilages of nose (quadrate), 928
lachrymal glands, 903
nerve, obturator, 850
spinal, 819
nucleus of auditory nerve, 812
of trigeminal nerve, 794
sensory, of trigeminal nerve, 794
palatine canals, 65
portion of spinal accessory nerve, 820
process of lumbar vertebra, 14
ALV
Accessory suprarenal bodies, 1050
vein, hemiazygos, 644
Acervulus [dim. of acervus = a heap] cerebri,
or brain sand, 747
Acetabulum [=a vessel for holding vinegar],
the, 148, 153

Acromial artery of acromio-thoracic, 555
of posterior circumflex, 558
of suprascapular, 546
end of clavicle, 119
Acromio-clavicular articulation, 230
Acromio-thoracic artery, 555
vein, 682
Acromion [akрov = a summit;
uos = shoulder]
process, 122; ossification of, 124
Adduction [ad=to; duco = I lead], 189
Adductor brevis muscle, 381; variations, 382
hallucis [hallux= great toe] muscle,
406; variations, 407
longus muscle, 379; variations, 379
magnus muscle, 382; variations, 383
pollicis [pollex = thumb] muscle, 362;
variations, 362
obliquus muscle, 361
tubercle of femur, 157
Adipose fossæ of breast, 1108
Age, variations of breast according to, 1109
variations in form of uterus according to,
1084
Ala [=a wing] cinerea [=ash-coloured], 758
Alæ of cerebellum, 754
of nose, 926
of sacrum, 17
of sphenoid, greater and lesser, 33
of thyroid cartilage, 939
vespertilionis, 1085
of vomer, 58
Alar [ala = a wing] ligaments of knee, 273
spine, 35, 83
Alar [alaris is a contraction of axillaris]
thoracic artery, 555
vein, 682
Alcock's canal, 858, 1099
Alimentary tube, the simple, 1029
Ali-sphenoid bones, 33; at birth, 101
Allantois [axxas, gen. àλλavтos = a sausage],
the, 1093
Alveolar artery, 526
nerves, 804
point of skull, 88
ridge of maxilla, 62
The names of Abnormal Muscles are printed in italics.
4 L 2
1252
INDEX
ALV
Alveolus [= a small hollow vessel] of mandible
(= inferior maxilla), 69
of maxilla (= superior maxilla), 62
Amphiarthrosis [àupí both; apopov = a joint],
187
=
Ampulla [= a wine-jug] of Fallopian tube, 1089
of galactophorous duct, 1109
of semicircular canals, 44, 917
of Vater, 1021
Amputation of great toe, incisions for, 1240
Hey's, incisions for, 1240
of leg, arteries divided in, 1233
Lisfranc's, incisions for, 1240
Syme's, incisions for, 1238
Amygdala [auvydáλn = an almond] of cere-
bellum, 755
Amygdaloid nucleus of cerebrum, 740
tubercle of cerebrum, 740
Anal fascia, 1102
Anastomotic [avaoтóμwσis an outlet] artery of
deep cervical, 551
=
of external plantar, 630
of internal plantar, 632
of middle meningeal, 525
of sciatic, 607
Anastomotica magna of brachial artery, 562;
variations, 563
of superficial femoral, 621
Anatomical neck of humerus, 124
Anatomy [avá apart; Téuvw= I cut], Topo-
graphical and Surgical, 1111
Anconeus [àykáv = the elbow] muscle, 345;
nerve to, 841
Andersch, ganglion of, 814
Angle, cranio-facial, 88
nasal, of maxilla, 62
of neck of femur, 162
of penis, 1070, 1075
of pubes, 152
of rib, 106
anterior, 107
sacro-vertebral, 209
of scapula, 122
subcostal, 117
Angular artery, 515, 518
centre of ossification, of mandible, 71
gyrus, 726
movement, 188
processes of frontal, 50
vein, 650
Ankle joint, arrangement of tendons around,
1233
arterial and nerve supply of, 281
ligaments of, 279
movements of, 281
surgical anatomy of, 1233
Annectant [= connecting] gyri, 728
=
Annular [annulus a ring] ligaments of ankle,
anterior, 390; external and internal, 391
of wrist, anterior, 328; surgical anatomy
of, 1204
posterior, 328; surgical anatomy
of, 1206
Annulus [a ring] ovalis, 968
Anomalus muscle, 487
Ansa [=a loop] hypoglossi, 821, 832
lenticularis, 784
peduncularis, 784
Vieussenii, 867
Anti-clinal vertebra, 13
AQU
Antihelix [avrí = opposite; eλ= a spiral], the,
908
Antitragicus muscle, 909
Antitragus [avrí= against; Tpάyos = a goat], the,
908
Antral arteries of posterior dental, 526
Antrum [= a cavern or cavity], mastoid, 43, 1114
maxillary (of Highmore), 60, 62
aperture of, 63, 87
Anus, the, 1011
surgical anatomy of, 1155
Aorta [from deípw = I take up, or carry], 495
abdominal, 584; branches, parietal, 586
visceral, 588
topography of, 1149
variations, 585
arch of, 495; branches of, 501
divisions of, ascending, 497
descending, 499
transverse, 498; branches,
501

topography of, 1141
variations of arch, 500
of branches, 501
foramen for, in diaphragm, 424
orifice of, 971; topography of, 972, 1140
thoracic, descending, 579
branches, parietal, 581; visceral, 579
relations, 579
Aortic intercostal arteries, 581
isthmus, 499
lymphatic glands, lumbar, 701
orifice, 971; topography of, 972, 1140
plexus of sympathetic, 871

spindle, 499
valves, 971; topography of, 972, 1140
Apertura scalæ vestibuli, 916
Aperture of larynx, superior, 947
palpebral, 874
of thorax, inferior, 935; superior, 934
Apex of antrum, 62
of heart, 963
of lung, 960
of orbit, 84
of petrosal portion of temporal, 38
of prostate, 1059
of sacrum, 17
Aponeurosis [aπó= from; veûpov = a nerve: so
called from a formerly existing confusion
between nerves and tendons] of dia-
phragm, 424
epicranial, 454
of external oblique muscle, 428
of internal oblique muscle, 431
lumbar, 433
occipito-frontal or epicranial, 454, 1115
pharyngeal, 985
transversalis, 434, 436
vertebral, 433, 438

Aponeurotic patch in trapezius muscle, ex-
planation of, 304
Apophysis [aπó = from; pú∞ = I grow], 162
Appendices epiploicæ, 1006
Appendicular elements of skull, 26
of chondral skull, 97

Appendix, auricular, 966
vermiform, 1007
Aquæductus [= a conduit] cochleæ, 39, 83
Fallopii, 39
vestibuli, 39, 916
INDEX
1253
AQU
Aqueduct of Sylvius, 709, 749
grey matter of, 750
Aqueous chamber of eye, 886
humour of eye, 886
Arachnoid [apáxvn- a spider's web; eldos =
=
like], cranial, 715
spinal, 773
Arantius, ventricle of, 758
Arbor vitæ uterina, 1084
Arch of aorta, 495. See Aorta
of atlas, anterior and posterior, 8
carpal, anterior, 568; posterior, 574
crural, deep, 1167; superficial, 1166
palmar, deep, 576; surgical anatomy of,
1204; variations, 576
superficial, 568; surgical anatomy of,
1203; variations, 569
plantar, 629
pubic, 155
of vertebræ, neural, 7
Arches of foot, 1242
function and maintenance of, 1246
Arciform [arcus a bow] fibres of medulla,
deep, 783; external, 762; superficial, 783
Arcus [= a bow] tendineus, 1099
Areola [= a small open space] of breast, 1109
Arm, central point of, surgical anatomy of,
1187
fascia of, 321
surgical anatomy of, 1186
veins of, deep, 682
superficial, 678
Arnold, ganglion of (=otic), 805
nerve of, 818
Arrangement of peritoneum in human body,
explanation of, 1028
Arteria aberrans of aortic intercostal, 583
of superior intercostal, 551
centralis retinæ, 531, 887
comes nervi ischiadici, 608
mediani, 566
phrenici, 548
receptaculi, 530
septi narium, 518
thyroidea ima, 504
Arterial side of heart, 965
Artery, or Arteries [àprýp = a strap or sus-
pender
a term applied originally to
the trachea, which suspends the lungs],
the, 491
accessory pudic, 605
acromial, of acromio-thoracic, 555
of posterior circumflex, 558
of suprascapular, 546
acromio-thoracic or thoracic axis, 555
alar thoracic, 555
alveolar, 526
anastomotic, of external plantar, 630
of internal plantar, 632
of middle meningeal, 525
of sciatic, 607
anastomotica magna, of brachial, 562;
variations, 563
of femoral, 621
angular, 515, 518
antero-lateral, of middle cerebral, 534
antral, 526
articular azygos, 625
articular, of external plantar, 630
of internal circumflex, 619
ART
Artery, or Arteries-
articular, of internal plantar, 632
of interosseous recurrent, 576
of popliteal, 624
of posterior circumflex, 558
of sciatic, 607
of superior profunda, 562
of suprascapular, 546
of temporal, 522
ascending cervical, 545
of external circumflex, 619
frontal, 535

palatine, 516
pharyngeal, 510
septal, of spheno-palatine, 527
tricipital, of superior profunda, 562
auditory, internal, 543, 920
auricular, anterior, 522
deep, 524
left, 503
posterior, 520
right, 502, 973
of occipital, 520
of stylo-mastoid, 521
axillary, 552; line of, 1184
variations, 553
azygos articular, 625
vaginal, 605

basilar, 543
bicipital, of anterior circumflex, 557
brachial, 559; surgical anatomy of, 1187;
variations, 561
brachio-cephalic (innominate), 503; varia-
tions, 504
bronchial, left and right, 581, 962
buccal, of facial, 517
of internal maxillary, 526
of posterior dental, 526
to bulb, 610

calcanean, external and internal, 628
of external plantar, 630
calloso-marginal of anterior cerebral, 534
capsular, perirenal, 594
suprarenal, inferior, 594; middle, 595;
superior, 587
cardiac, of gastric, 590
carotid, common, 504; in thorax (left),
505; in neck, 506; collateral circu-
lation, 509; variations, 509
external, 509; variations, 510
internal, 528
carpal, radial, 574
rete, anterior, 566, 568
posterior, 566, 574
ulnar, 568
caudate, of middle cerebral, 534
caval, of right phrenic, 587
central, of retina, 531, 887
cerebellar, inferior, anterior, 543

posterior, 542
superior, 543
cerebral, anterior, 534, 545
hæmorrhage, artery of, 535
middle, 534, 545
posterior, 543, 545
cervical, ascending, 545
deep, 551
superficial, 548
transverse, 546
of uterine, 606
1254
INDEX
Artery, or Arteries-
ART
choroid, anterior, 533
posterior, 544
ciliary, 532, 888
circumflex, of axillary, anterior, 557;
variations, 557
posterior, 557; variations, 558
iliac, deep, 613; variations, 613
superficial, 618
of thigh, external, 619; variations, 619
internal, 619; variations, 620
clavicular, 555
coccygeal, 607
coeliac, 588; variations, 589
colic, left, 596; middle, 593; right, 593
collateral digital, of fingers, 571
of toes, 631
intercostals, 582
commissural, of anterior cerebral, 534
communicating, of brain, anterior, 534
of dorsalis pedis, 637
of occipital, 520
of palm, 579
of peroneal, 628
of posterior tibial, 628
posterior, 533
coronary, of heart, left, 503, 973
right, 502, 972
of lips, inferior, 517; superior, 518
of stomach, 589; variations, 590
of corpus cavernosum, 611, 1104
cortical, of anterior cerebral, 534
of middle cerebral, 535
of posterior cerebral, 544
of renal, 1049
costo-cervical, 550
cremasteric, of deep epigastric, 612
of spermatic, 595
crico-thyroid, 513
to crus clitoridis, 611
penis, 611
cystic, 591
deferential, or artery to the vas, 604
dental, anterior, 527
inferior (= mandibular), 525
posterior, 526
descending, of external circumflex, 619
palatine, 527
pharyngeal, 527
diaphragmatic, 583
digital, of foot, collateral, 631
dorsal, 636, 637
plantar, 630, 637
superficial, 632
of hand, collateral, 571
dorsal, 575
palmar, 570
diploic, 531
dorsal, of aortic intercostal, 582
digital, of foot, 636, 637
of hand, 575
of foot, 634
interosseous, of radial, 574
of lumbar, 588
of penis, 611, 1104
scapular, 556
twelfth (subcostal), 583
dorsalis hallucis, 636
indicis, 576
linguæ, 514
ART
dorsalis pedis, 634
pollicis, 576
epididymal, of spermatic, 596
epigastric, deep, or inferior, 612; variations,
613
superficial, 618
superior, 550
epiploic, of left gastro-epiploic, 592
of right gastro-epiploic, 591
ethmoidal, anterior and posterior, 532, 934
Eustachian, of pterygo-palatine, 527

of Vidian, 527
facial, 515
transverse, 522
Fallopian, of ovarian, 596
femoral, common, 614; variations, 616
deep, 618
superficial, 614; surgical anatomy of,
1214; variations, 616
of frænum linguæ, 515
funicular, 1088, 1092
ganglionic, of anterior cerebral, 534
of internal carotid, 530
of middle cerebral, 534
of posterior cerebral, 544
Gasserian, of internal carotid, 530
of middle meningeal, 524
gastric, or coronary, 589; variations, 590;
greater anterior, 590
lesser anterior and posterior, 590
of left gastro-epiploic, 592
of right gastro-epiploic, 591
gastro-duodenal, 590
gastro-epiploic, left, 592


gingival, 526
right, 591
glandular (= submaxillary), 517
Glaserian, of internal maxillary, 524
gluteal, 602; surgical anatomy of, 1219
inferior, of sciatic, 607
gustatory (lingual), of inferior dental,
525
hæmorrhoidal, inferior, or external, 609
middle, 605
superior, 597
hemispheral, of inferior cerebellar, 542
of superior cerebellar, 543
hepatic, 590; variations, 591
of gastric, 590
of phrenic, 587
of superior epigastric, 550
humeral, of acromio-thoracic, 555
transverse, 546
hyoid, of lingual, 514
of superior thyroid, 513
hypogastric, 604, 1163
ileo-colic, 594
iliac, circumflex, deep, 613; variations, 613

superficial, 618
common, 598; collateral circulation,
600; variations, 599
external, 611; collateral circulation,
612; variations, 612
internal, 600; variations, 600
of ilio-lumbar, 602
of obturator, 606
ilio-lumbar, 601
incisive, 525
infracostal, lateral, 550
infra-hyoid, 513
INDEX
1255
ART
Artery, or Arteries-
infra-orbital, 526
infrascapular, 556
infraspinous, of posterior scapular, 547
of suprascapular, 546
innominate, 503; variations, 504
intercostal, anterior, of int. mammary, 549
of musc.-phrenic, 550
aortic, 581
first, 551
superior, 550
interosseous, of arm, common, 565
anterior, 566
posterior, 566
recurrent, 566
of foot, 636
of hand, dorsal, 574
palmar, 579
interventricular, anterior, 503, 973
intestinal, 594
posterior, 502, 972
labial, inferior, 517
lachrymal, 530
of nasal, 533
of middle meningeal, 524
recurrent, 530
laryngeal, inferior, of inferior thyroid, 546
of superior thyroid, 513
superior, of superior thyroid, 513
lenticulo-striate, 534
ligamentous, of ovarian, 596
lingual, 513
of mandibular (= inferior dental), 525
lumbar, 587; variations, 588
of ilio-lumbar, 602
malleolar, external, of anterior tibial, 634
internal, of anterior tibial, 634
of posterior tibial, 628
mammary, external, 555
glandular, 583
internal, 548
mandibular (= inferior dental), 525
marginal, of coronary, left, 503, 973
margino-frontal, 534
right, 502, 973
masseteric, of facial, 517
of internal maxillary, 526
of temporal, 522
mastoid, middle, 513
of occipital, 520
of posterior auricular, 521
of stylo-mastoid, 521
maxillary, external (= facial), 515
internal, 522
meatal, of stylo-mastoid, 521
median, 566
mediastinal, or thymic, 548
posterior, 579
medullary, of peroneal, 627
of posterior tibial, 628
of renal, 1049
meningeal, anterior, of internal carotid, 530
of ascending pharyngeal, 511, 713
of ethmoidals, 532, 713
middle or great, 524, 713
posterior, of occipital, 520
of vertebral, 542, 713
small, 525, 713
mental, of facial, 517
of mandibular, 525
ART
mesenteric, inferior, 596; variations, 597
superior, 592; variations, 594
metacarpal, 575
metatarsal, 636
musculo-phrenic, 550
mylo-hyoidean, 525
nasal, of infra-orbital, 527
lateral, 518
of ophthalmic, 533
transverse, 533
of spheno-palatine, 527
of nasal fossæ, 934
na so-palatine, 527, 934
of nose, 930
nutrient, of clavicle, 546
of femur, 620
of fibula, 627
of humerus, 563; greater tuberosity,
558; upper end, 562
of ilium, 606
of radius, 566
of tibia, 628
of ulna, 566, 568
obturator, 606
occipital, 518

of posterior auricular, 521
cesophageal, of aorta, 581
of gastric, 590
of inferior thyroid, 546
of left phrenic, 587
omental, of hepatic, 590
ophthalmic, 530, 899
orbital, of anterior cerebral, 534
of infra-orbital, 527
of middle meningeal, 524
of temporal, 522
orbito-frontal, 535
ovarian, 596, 1091
palatine, inferior or ascending, 516
posterior or descending, 527
of ascending pharyngeal, 511
palmar arch, deep, 576; variations, 576
superficial, 568; variations, 569
palpebral, 533
of lachrymal, 531
of supra-orbital, 531
pancreatic, of hepatic, 590
of splenic, 592
pancreatico-duodenal, inferior, 593
superior, 591
parietal, of middle cerebral, 535
ascending, 535
parieto-temporal, 535
parotid, of posterior auricular, 521
of temporal, 522
pectoral, of acromio-thoracic, 555
of anterior circumflex, 557
perforating, of foot, 630
of hand, 579
of internal mammary, 549
of middle meningeal, 525
of profunda femoris, 620
of spheno-palatine, 527
of submental, 517
pericardiac, of internal mammary, 549
of phrenic, inferior, 587
of thoracic aorta, 579
perinæal, superficial, 609
transverse, 610
perirenal, 594
1256
INDEX
ART
ART
Artery, or Arteries-
peritoneal, of common iliac, 600
of superior epigastric, 550
peroneal, 627
anterior, 627
posterior, 628
petrosal, 524, 915
pharyngeal, ascending, 510
of pterygo-palatine, 527
of spheno-palatine, 527
of Vidian, 527
phrenic, inferior, left, 587
right, 586
of inferior thyroid, 546
of musculo-phrenic, 550
superior, 548
of superior epigastric, 550
pituitary, 530
plantar arch, 629
digitals, 630, 637
external, 628
internal, 631
pleural, 582
pontal, 543
popliteal, 621; surgical anatomy of, 1227,
1231; variations, 623
postero-lateral, of posterior cerebral, 544
postero-median, of posterior cerebral, 544
preventricular, 502, 973
prevertebral, 511
princeps cervicis, 520
hallucis, 637
pollicis, 577
profunda, of brachial, inferior and superior,
562; variations, 562
of femoral, 618
pterygoid, external and internal, 526
pterygo-palatine, 527
pterygo-pharyngeal, 527
pubic, of epigastric, 613
of obturator, 606
pudic, accessory, 605
external, deep, 618
superficial, 618
internal, 608, 1106; surgical anatomy
of, 1219
pulmonary, 491, 962
left, 495
right, 493
pyloric inferior, 591
superior, 590
quadrate, 534
radial, 571
in forearm, 571; variations, 572
in palm, 576; variations, 576
at wrist, 574
carpal, anterior and posterior, 574
recurrent, 573
radialis indicis, 577
ranine, 515
rectal, of lateral sacral, 602
of middle sacral, 598
recurrent, of deep palmar arch, 579
interosseous posterior, 566
radial, 573
tibial, anterior and posterior, 634
ulnar, anterior and posterior, 565
renal, 594; variations, 594
sacral, lateral, 602
middle, 598; variations, 598
scapular, dorsal, 556
posterior, 547
sciatic, 607; surgical anatomy of, 1219
septum, artery of, 527
sigmoid, 597
spermatic, 595; variations, 596
sphenoidal, of pterygo-palatine, 527
of spheno-palatine, 527
spheno-palatine, 527, 934
spinal, anterior, 542
of inferior thyroid, 545
of intercostals, 582
lateral, 542
of lateral sacral, 602
posterior, 542
splenic, 591; variations, 592
of left phrenic, 587
stapedic, 521
sternal, 549
sterno-mastoid, of occipital, 520
of superior thyroid, 513
inferior, of suprascapular, 546
stylo-mastoid, 521, 915
subclavian, 536; variations, 539
of suprascapular, 546
subcostal, 583
sublingual, 515
submaxillary, 517
submental, 517

subscapular, 555; variations, 557
of posterior scapular, 547
of suprascapular, 546
supra-hyoid, 514
supra-orbital, 531
suprarenal, inferior, 594, 1051,
middle, 595, 1051
superior, 587, 1051
suprascapular, 546
supraspinous, of posterior scapular, 547
of suprascapular, 546
suprasternal, 546
sural, 624
tarsal, external and internal, 636
temporal, of posterior cerebral, 544
deep, anterior and posterior, 526
middle, 522
superficial, 521
temporo-occipital, 544
testicular, 596
thalamic, middle, 533
thoracic, acromial, 555

alar, 555
axis, 555
long, 555
short or superior, 555
twelfth (subcostal), 581
thymic, 548
thyroid axis, 545
inferior, 545
superior, 512
thyroidea ima, 504
tibial, anterior, 632
posterior,626; surgical anatomyof, 1231
tonsillar, of facial, 517
of inferior palatine, 517
tracheal, 546
transversalis colli, 546
humeri, 546
transverse, of basilar, 543
cervical, 546
INDEX
1257
Artery, or Arteries-
ART
transverse, of external circumflex, 619
facial, 522
humeral, 546
nasal, 533
perinæal, 610
of right coronary, 502
tricipital, of posterior circumflex, 558
of superior profunda, 562
tubal, 1092
tympanic, of ascending pharyngeal, 511
of internal maxillary, 524, 915
of middle meningeal, 524
of stylo-mastoid, 521
of Vidian, 527
ulnar, 563
in forearm, 564; variations, 565
in palm, 568; variations, 569
at wrist, 568
carpal, anterior and posterior, 568
recurrent, anterior and posterior, 565
uncinate, of posterior cerebral, 544
of posterior communicating, 533
uracheric, 604
uretal, of ovarian, 596
of renal, 594
of spermatic, 595
ureteric, of common iliac, 600
of superior vesical, 604
uterine, 605, 1091
of ovarian, 596
vaginal, 606
azygos, 606
vas, artery to, 604
vasa brevia, 592
vermiform, inferior, 542
superior, 543
vertebral, 540; variations, 541
vesical, inferior, middle, and superior, 604
of obturator, 606
vestibular, 521
Vidian, 527
volar, superficial, 574
xiphoid, 550
zygomatico-orbital, 522
Arthrodia [ap@pwdía = a shallow joint], 187
Articular [articulus = a joint; dim. of artus
= limb]-
arteries, of circumflex, posterior, 558
of interosseous recurrent, 567
of plantar, external, 630; internal, 632
of popliteal, 624
azygos, 625
of profunda, superior, 562
of sciatic, 607
of suprascapular, 546
of temporal, 522
eminence, 38, 77
nerves, of auriculo-temporal, 803
of circumflex, 835
of crural, anterior, 852
of interosseous, posterior, 841
of median, 838
of obturator, 849
of popliteal, external, 859; internal, 861
of tibial, anterior, 860; posterior, 863
recurrent, of external popliteal, 859
ulnar, 840
process, of atlas, 8; of axis, 9; of coccyx,
18; of fifth lumbar vertebra 15, morpho-
ART
logy of 25; of sacrum, 16; of twelfth
dorsal vertebra, 13; of typical vertebra,
6; of typical cervical vertebra, 7; of
typical lumbar vertebra, 13
surface, of acromion, 122
of head of tibia, 163
vein of temporal, 652
=
Articulations [articulus a joint], structures
entering into the formation of, 186, 187
tabular classification of, 188
varieties of, 187, 188
acromio-clavicular, 230
of ankle, 269
of articular processes of vertebræ, 205
astragalo-scaphoid, 287
atlanto-axoidean, 196
of auditory ossicles, 913
of bodies of the vertebræ, 201
calcaneo-astragaloid, 282
calcaneo-cuboid, 288
carpal, 249
carpo-metacarpal, 253
chondro-sternal, 222
coraco-clavicular, 231
costo-central, 219
costo-chondral, 224
costo-transverse, 221
crico-arytenoid, 944
crico-thyroid, 944
cubo-cuneiform, 286
cubo-metatarsal, 291
cubo-scaphoid, 285
of elbow, 239
of heads of metacarpal bones, 255
of metatarsal bones, 293

of hip, 259
of incus with stapes, 913
interchondral, 225
intercoccygeal, 216
intercuneiform, 286
intermetacarpal, 255
intermetatarsal, 292
interphalangeal, of fingers, 258
interpubic, 216
intersternal, 224
of knee, 266
of toes, 294

of the laminæ of the vertebræ, 205
of larynx, 944
of malleus with incus, 913
medio-carpal, 250
medio-tarsal, 286
metacarpo-phalangeal, 256
metatarso-phalangeal, 293
occipito-atlantal, 193
occipito-axoidean, 198
of the pelvis, 211
of the pelvis with the spine, 209
of pisiform bone with the carpus, 249
radio-carpal, 245
radio-ulnar, inferior, 243

middle and superior, 242
of radius with ulna, 241
of ribs with the vertebræ, 218
sacro-coccygeal, 214
sacro-iliac, 211
scapho-cuneiform, 285
scapular ligaments proper, 232
scapulo-clavicular union, 230
of shoulder, 234
1258
INDEX
Articulations-
of skull, 189
ART
of spinous processes of vertebræ, 206
of stapes with fenestra ovalis, 914
sterno-clavicular, 227
tarso-metatarsal, external, 291; internal,
290; middle, 291
temporo-mandibular (maxillary), 189
tibio-fibular, inferior and middle, 278
superior, 277
of the transverse processes, 207
of the trunk, classification of, 200
of the vertebral column, classification,
200
Aryteno-epiglottidean folds,,942
Aryteno-epiglottideus muscle, 947
Arytenoid [apúrava a pitcher; eidos = like]
cartilages, 941
Arytenoideus muscle, 947
Ascending branch, of ext. circumflex artery, 619
of superior cervical ganglion, 865
of superior profunda artery, 562
branches of cervical plexus, 830
of Meckel's ganglion, 800
cervical artery, 545
frontal artery, 535
convolution, 724
palatine artery, 516
parietal convolution, 726
pharyngeal artery, 510
root of glosso-pharyngeal nerve, 813
of trigeminal nerve, 794
septal artery, 527
Asterion [aornp= a star: from the radiating
manner in which the sutures diverge
at this spot], the, 78, 1111
Astragalo-scaphoid articulation, arterial sup-
ply of, 288
ligaments of, 287
movements and nerve-supply of, 289
Astragalus [àoтpayaλos a die; these bones
were used by the ancients for a game
like dice], the, 169
articulations of, 172
ossification of, 172
os trigonum of, 172
Atlanto-axoidean articulations, arterial and
nerve supply of, 198
ligaments of, 196
movements of, 198
=
Atlas [TAάw I sustain, from its support to the
head], the, 8
muscles attached to, 10
ossification of, 21
Atrium [= a forecourt] of heart, 966
Attic of tympanum, 43
Attollens [attollo = I raise] aurem muscle, 458
Attrahens [attraho= I draw forward] aurem
muscle, 458
Auditory [audio = I hear] artery, 543, 920
meatus, external, 40, 83, 909
internal, 38, 93, 104
nerve (eighth cranial), 811; branches, 813,
920; roots, 811
Auricle [auricula = a little ear] of ear, 907
muscles of, extrinsic, 458
intrinsic, 909
of heart, left, 970
right, 966
Auricular appendix, 966
BAR
Auricular artery, anterior, 522
of coronary, left, 503; right, 502
deep, 524
of occipital, 520
posterior, 520; topography of, 1118
of stylo-mastoid, 521
canaliculus, 40
cartilage, of sacro-iliac articulation, 212
fissure, 40, 84
lymphatic glands, posterior, 689
muscles, extrinsic, 458
intrinsic, 909
nerve, anterior, 803
great, 830

of lesser occipital, 829
posterior, 808
of vagus (Arnold's), 818
point of skull, 78
portion of foetal heart, 977
process of inferior turbinal bone, 57
septum, 968
surface of ilium, 148
veins, of ear, 653, 663,
of heart, left, 646, 974; right, 647
Auriculo-temporal nerve, 803
Auriculo-ventricular groove, 965
openings, 966, 970; topography of, 1140
Axes of skull, 88
Axilla, surgical anatomy of, 1184
Axillary artery, 552; variations of, 553
border of scapula, 122
fascia, 308
lymphatic glands, 695
trunk, 695
nerves, of brachial plexus, 835
vein, 682
Axis (vertebra) [so called from its pivot-like
articulation with the atlasj, the, 9
muscles attached to, 11

ossification of, 22
basi-bregmatic, of skull, 88
basi-cranial, of skull, 88
basi-facial, of skull, 88
central, of cochlea, 918
coeliac, 588; variations, 589
of pelvis, 156
sagittal, of eyeball, 878
thoracic, 555
thyroid, 545
Azygos [Cuyos = single] artery, articular, 625
muscle, pharyngis, 487
uvulæ, 981
veins, major, 642
minor and tertia, 644
vaginal, 605

BACK, surgical anatomy of the, 1170
Band, furrowed, 755
ilio-femoral, 259
ilio-tibial, 364
ischio-femoral, 260
moderator, of heart, 969
pectineo-femoral, 260
sterno-pericardial, 962
tendino-trochanteric, 261
Bars, branchial, 97
hyoid, 98
mandibular, 97
thyroid, 98
INDEX
1259
BAR
Bartholin, glands of, 1077, 1107
Basal ganglia of cerebral hemispheres, 739
grey commissure, 748
ridge (cingulum) of tooth, 94
Base of antrum, 62
of brain, 719
of epididymis, 1062
of heart, 963
of lung, 958
of petrosal portion of temporal bone, 38
of sacrum, 17
of skull, exterior, 78; interior, 89
of thorax, 935
Basi-bregmatic axis of skull, 88
Basi-cranial axis of skull, 88
region in chondral skull, 97
Basi-facial axis of skull. 88
Basi-hyal bone, or body of hyoid, 72
centre of ossification, 103
Basilar [basis the base] artery, 543
bones, 26
sinus (=transverse), 659
suture, 93
vein, 662; tributaries, 662
Basilic [according to Hyrtl, from the Arabic
al-basilik=the inner (vein)] vein, 681
median, 680
Basi-occipital bone, 26; at birth, 100
Basion [Báois= base], the, 82, 88
Basi-sphenoid nucleus, 35
Bertin, bones of, 56
Biceps [bis twice; caput = a head]-
flexor cubiti muscle, 323; nerve to, 837;
variations, 324
flexor femoris muscle, 385; variations, 385
Bicipital artery of anterior circumflex, 557
groove of humerus, 124, 1182
rib, 111
tuberosity of radius, 13
Bicuspid [bis twice; cuspis = a point or pro-
jection] teeth, 95
valve of heart (= mitral), 972; topography
of, 972
Bifid [bis twice; findo I cleave] cervical
spinous processes, 10
metasternum (xiphoid), 114
Bile duct, common, 1021
Bipenniform [penna a feather] muscles, 297
Biventral [bis - twice; venter = belly] lobe of
cerebellum, 754
Bladder, gall, the, 1020; duct of, 1021; struc-
ture of, 1022; topography of, 1146
urinary, the, 1053
development of, 1093
effects of distension on, 1055
female and infantile, 1058
form of, 1053
ligaments of, 1056
lymphatics of, 702
relations of, 1054
structure of, 1056
vessels and nerves of, 1058
Blood-vessels, see Arteries and Veins; and for
the vascular supply of the various
organs, see those organs
Bochdalek, ganglion of, 799
Bone, or Bones, cancelli [= lattices] of, 4
compound, 1
marrow of, 4
medullary cavity of, 4
BON
mode of development of, 2
pressure and tension curves, 4
shafts of, 4
structure of, 4
individual-
astragalus, 169
atlas, 8
axis, 9
basilar, 26
of Bertin, 56
calcaneum, or os calcis, 173
carpal, 137

central, of carpus, 142
clavicle, 118
соссух, 18
cotyloid, 153
cuboid, 175
cuneiform, of carpus, 140
of tarsus, 177
epipteric, 53
episternal, 113
ethmoid, 53
femur, 156
fibula, 168
of foot, 169
frontal, 50
of hand, 137
of head, 26
hip bone, 148
humerus, 124
hyoid, 72
ilium, 148
incus, 74
innominate, 148
ischium, 149
lachrymal, 58
lingual (=hyoid), 72
magnum, 142

malar, 66
malleus, 72
mandible, or inferior maxilla, 68
maxilla, or superior maxilla, 60
metacarpal, 143
metatarsal, 179
nasal, 59
occipital, 26
palate, 64
parietal, 48
patella, 162
pelvis, 155
phalanges, of foot, 183
of hand, 146
pisiform, 140
pubic, 151
radius, 135
ribs, 106
sacrum, 15
scaphoid, of carpus, 138
of tarsus, 176
scapula, 120
semilunar, 139
sesamoid, of foot, 181, 293
of hand, 143, 257
of skull, 26
sphenoid, 32
sphenoidal turbinal, 56
stapes, 75
sternum, 106
styloid, of carpus, 146
process, 73
1260
INDEX
Bone, or Bones-
individual
tarsal, 169
temporal, 37
tibia, 163
BON
trapezium, 141
trapezoid, 141
turbinal, inferior, 57
ulna, 131
sphenoidal, 56
unciform, 142
vertebra prominens, 9
vertebræ, 5
cervical, 7
dorsal, or thoracic, 12
lumbar, 13
sacral and coccygeal, 15
vestigial, 169
vomer, 58
Wormian, 53
Boundary zone of Lissauer, 782
Bowman's membrane, 882
Brachia [Bpaxiwv an arm] of nates, 751
of testes, 751
Brachial artery, 559; surgical anatomy of,
1187
variations, 561
plexus, 832; branches above clavicle, 834
below clavicle, 835
venæ comites, 682
Brachialis anticus muscle, 325
nerves to, 325, 837, 841
Brachio-cephalic [Bpaxíwv=the arm; kepaλń
= the head: so called from its distribu-
See Innominate
tion].
artery, 503
vein, 640
Brachio-radialis (= supinator longus) muscle,
339; variations, 339
Brain, the, 718
basal ganglia of, 739
base of, 719
epencephalon, 753
hemispheres of, 720
lymphatics of, 717
meninges of, 711
mesencephalon, 749
metencephalon, 760
sinuses of, 656, 711
thalamencephalon, 745
topography of, 766
weight and specific gravity of, 766
Brain sand (acervulus cerebri), 747
Branchial [Bpáyxia = gills] bars, 97
Breast, female, 1108. See Mamma
male, 1109
Bregma [Bpéxw= I moisten], the, 75, 88, 1111
Broad ligament, of liver, the, 1019
of uterus, 1085; structures between
layers of, 1086
Bronchi [Bpóyxos = the windpipe], 952
Bronchial [Bpóyxos = the windpipe] artery, 581
lymphatic glands, 697
nerves, 962
veins, 645, 962
Bronchioles [dim. of bronchi], the, 952
Broncho-mediastinal lymph trunk, 697
Bruch, membrane of, 882
Brunner's glands, 1004
Bryant's triangle, 1210
CAN
Buccal [bucca-mouth] artery of facial, 517
of internal maxillary, 526
of posterior dental, 526
fat pad, 464
lymphatic glands, 689
nerve of facial, 810
long, 803
orifice, 979
portion of pharynx, 985
vein, 651, 653
Buccinator [buccina = a trumpet; from its use
in blowing that instrument] muscle,
462
Bulb, the (= medulla oblongata), 760
artery of, 610
of cornu of lateral ventricle, 736
olfactory, 788
ovarian, 671
urethral, 1071
Bulbi [bulbus = a bulb] vestibuli, 1078, 1107
Bulbo-cavernosus, or accelerator urinæ muscle,
1072, 1079
Bundle, ground, of spinal cord, anterior and
posterior, 781
longitudinal, of crus cerebri, posterior,
753, 781, 783
of Vicq d'Azyr, 743, 748, 784
Burdach's column, of spinal cord, 782
Burns, falciform process of, 1166
Bursa [=a sac], great palmar, 334
pharyngeal, 987
prepatellar, 1223
Bursæ of foot, 1241; popliteal, 1226
Buttocks, surgical anatomy of the, 1216
CECUM [cacus = blind], the, 1006; variations
of, 1006
Calcanean [calx = the heel] artery, external, 628
internal, 628
of external plantar, 630
nerve, internal, 863

Calcaneo-astragaloid joint, anterior, 283
posterior, 282

movements of, 283
Calcaneo-cuboid joint, ligaments, 288
functions of, 1247
nerve-supply and movements of, 289
Calcaneo-plantar cutaneous nerve, 863
Calcaneo-scaphoid ligament, external, 283
inferior, 287; functions of, 1246
Calcaneum [calx = the heel], the, 173
articulations, 175
ossification, 175
Calcar [=a spur] avis [=of a bird], or hippo-
campus minor, the, 736
Calcarine fissure, the, 731
Calcis [calx= the heel], os, 173. See Calca-
neum
Calices [calix = a cup] of kidney, 1047, 1051
Callosal fissure, 731
Calloso-marginal artery, 534
fissure, 730
Calyciform (circumvallate) papillæ of tongue,
921
Canal, Alcock's, 858, 1099
carotid, 39
central, of cochlea, 918
clavicular, 118
of Cloquet, 887
INDEX
1261
CAN
Canal, cranio-pharyngeal, 32; at birth, 101
dental, anterior, 61, 84
inferior, 69, 105
ethmoidal, 50, 54, 85, 92, 104
Fallopian, 40, 43, 912
femoral, 1167
of Huguier, 40, 83, 105
of Hunter, 1214
hyaloid, 887
infra-orbital, 61, 105
inguinal, 1144, 1160
lachrymal, 84, 906
malar, 66, 105
mandibular, 69, 105
membranous, of cochlea, 920
neuro-enteric, 749
of Nuck, 1088
palatine, accessory, 65
anterior, 62, 86
external, 65
posterior, 65, 77, 105
of Petit, 886
petro-mastoid, 43
pterygo-palatine, 35, 65, 77, 105
spiral, 917
Vidian, 35, 77, 105; at birth, 101
of Wirsung, 1024
Canaliculi (dim. of canalis = a canal) lachry-
males, 905
Canaliculus, auricular, 40
tympanic, 40, 83
Canalis musculo-tubarius, 43, 82
reuniens, 918
Canals, gubernacular, 79
hepatic, 1020
portal, 1020
semicircular, 916
Stenson's, 62
Canine [canis = a dog; because the canine teeth
are most prominent in the dog]
eminence, 60
fossa, 60
teeth, 95
Canthus [káv0os = the angle of the eye], inner
and outer, 875
Capitellum [dim. of caput = the head], the, 129
Capsular [dim. of capsa a box] artery, or peri-
renal, 594
=
or suprarenal, inferior, 594; middle,
595; superior, 587
ligament of acromio-clavicular articula-
tion, 230
of atlanto-odontoid articulation, 197
of carpo-metacarpal joint of thumb, 254
of costo-central articulation, 219
of costo-transverse articulation, 221
of crico-arytenoid articulation, 944
of crico-thyroid articulation, 944
of elbow joint, 239
of hip joint, 259
of inco-stapedial articulation, 913
of interchondral articulation, 225
of knee joint, 269
of lateral atlanto-axoidean articulation,
196
of malleo-incal articulation, 913
of occipito-atlantal articulation, 193
of pisiform-cuneiform articulation, 249
of shoulder joint, 234
of sterno-clavicular articulation, 227
CAR
Capsular ligament of superior tibio-fibular
articulation, 277
of temporo-mandibular (maxillary)
articulation, 190
of vertebral articular processes, 205
vein (suprarenal), 671, 1051
Capsule of cerebrum, external, 742, 786

Glisson's, 1020
of spleen, 1028
of Tenon, 897
internal, 741
For capsule of joints, see Capsular liga-
ments
Capsules, Bowman's, 1048
Caput coli (=the cæcum), 1006; variations, 1006
Cardiac [kapdía = heart] artery of gastric, 590
ganglion of Wrisberg, 975
lymph glands (= superior mediastinal), 697
nerves of pneumogastric, 819
of sympathetic, 867, 868
orifice of stomach, 996
plexuses, superficial and deep, 870, 975
veins, anterior and posterior, 647, 974
great, 646, 973
smaller, 647


anterior, 648
Carina [a keel] of vagina, 1081
Carotico-clinoid ligament, 35
Carotid [kapów - I induce sleep: pressure on
them was supposed to cause sleep]-
artery, common, 504; collateral circulation,
509; relation of left artery to chest-
wall, 1141; variations, 509
external, 509; surgical anatomy of,
1118; variations, 510
internal, 528
canal, 39, 83
gland, 507
lobe of parotid gland, 963
plexus of sympathetic, 865
triangles, surgical anatomy of, 1129
Carpal [kaрrós = the wrist] arch, see Carpal rete
artery, radial, anterior and posterior, 574
ulnar, anterior and posterior, 568
bones, see Carpus, bones of
joints of first row, 249
of second row, 250
ligaments, 249, 250, 251
rete [a net], or carpal arch, anterior and
posterior, 566
Carpo-metacarpal joints of fingers, 253


ligaments, 253
of thumb, 254
Carpus [kаprós = wrist], bones of the, 137;
ossification of, 142
medio-carpal joint, ligaments of, 250
movements of carpal joints, 251
Cartilage, articular, of shoulder joint, 236
costal, 110; development of, 110
cricoid, 940
periotic, of chondro-cranium, 97
pre-coracoid, 124
=
sphenotic [ophy a wedge; ous = the ear], 97
tarsal, 455, 903
thyroid, 939
See also Fibro-cartilage
Cartilages, accessory quadrate, 928
arytenoid, 941
cuneiform, 943
Jacobsonian, 928
1262
INDEX
CAR
CHO

Cartilages, of larynx, 938
of nose, 927
lateral, 927; origin of, 103
septal, 928; origin of, 104
sesamoid, 920
of Santorini, 942
of Wrisberg, 943
Cartilaginous cranium, the, 97; remnants of,
103
framework of ear, 908
portion of Eustachian tube, 913
of external auditory meatus, 910
of nose, 926
rings of trachea, 951, 952
Cartilago triticea [= like a wheat grain], 943
Caruncle, lachrymal, 875, 878
Carunculæ [dim. of caro = flesh] myrtiformes
[myrtus = myrtle], 1157
Cauda equina [= a horse's tail], the, 776, 823
Caudal aorta. See Coccygeal glomerulus
Caudate lobe of liver, 1015
Cava [-hollow], vena, inferior, 669
tributaries, 670; variations, 672
superior, 639
Caval artery of right phrenic, 587
Cavernous groove, 33
nerves, of penis, large and small, 873
plexus, of sympathetic, 865
sinus, 660
Cavities of heart, 965
Cavity, cotyloid, 148, 153
sigmoid, of radius, 137
of ulna, greater, 131; lesser, 132
of true pelvis, 155
of uterus, 1084
Cavum [a hollow] Retzii, 1055
Cells, ethmoidal, 55, 87; development of, 55
fronto-ethmoidal, 55
lachrymo-ethmoidal, 55
mastoid, 43, 1114
maxillo-ethmoidal, 55
palato-ethmoidal, 55
spheno-ethmoidal, 55
Central artery of anterior cerebral, 534
of the retina, 531, 887
axis of cochlea, 918
canal of cochlea, 918
spinal cord, 778
connective tissue of orbit, 903
element (bone) of carpus, 142
grey matter of third ventricle, 746
lobe of cerebrum, 729
odontoid ligament, 200
point of arm, topography of, 1187
sulcus (= fissure of Rolando), 722
tendon of diaphragm, 424
vein, cerebral (= ganglionic, or deep), 662
of retina, 664
Centres of ossification. See Ossification, cen-
tres of
Centrum [= centre] of typical vertebra, 6;
morphology of, 25
of axis, 9
of fifth lumbar, 15
ovale majus et minus, 729
of typical cervical vertebra, 7
lumbar vertebra, 13
Cephalic [according to Hyrtl, from the Arabic,
al-kifal] vein, 680
median, 679
=
Cerato-hyals [Képas a horn; and u the letter
upsilon, 73
Cerebellar arteries, anterior, or ant. inferior, 543
posterior inferior, 542
superior, 543
commissure, 784
peduncle, superior, 753
root of trigeminal nerve, 794
tract of spinal cord, direct, 781
veins, inferior, 663; superior, 662
Cerebellum [dim. of cerebrum], 709, 753
fibres of, 783
grey matter in interior of, 756
white matter of, 756
Cerebral arteries, anterior, 534, 545
middle, 534, 545
posterior, 543, 545
distribution of, 544
hæmorrhage, artery of, 535
hemispheres, 709, 720
convolutions and fissures of, 723
topography of, 769
lymphatics, deep, 691


veins, 661
vesicles, 708
=
Cervical [cervix the neck] artery of uterus, 606
deep, of superior intercostal, 551
superficial, 548
transverse, 546
cardiac nerves of sympathetic, 868

of vagus, 819
enlargement of spinal cord, 774
fascia, deep, 472, 1130; functions of, 1134
ganglion, inferior, 867
middle, 867
superior, 865
lymphatic glands, deep, 692
superficial chain, 691
nerve, superficial, 831
transverse, topography of, 1130
nerves, anterior primary divisions of, 828
posterior primary divisions of, 825
plexus, 829
branches, deep, 831
superficial, 829
to hypoglossal from, 821
portion of gangliated cord of sympathetic,
864

rib, 111
tubercles of femur, 156
vein, deep, 652, 666
transverse, 654
vertebra, typical characters, 7
peculiar vertebræ, 8
seventh, 9; muscles attached to, 16
Cervicalis ascendens muscle, 441
Cervico-basilar ligament, 198
Cervico-facial division of facial nerve, 810
Cervix [= neck] of uterus, 1083; cavity of, 1084
Chambers of eyeball, 886
Characters, general, of foetal skull, 98
of typical rib, 108
of vertebra, 6

Check (lateral occipito-odontoid) ligaments, 198
Cheeks, the, 979
Chiasma [xiásw=I cross], optic, 749, 790;
fibres of, 790
Chin, the, 68
Chondro-cranium [xóvopos = cartilage], the, 97
Chondro-epitrochlearis muscle, 487
INDEX
1263
CHO
Chondro-glossus (=hyo-glossus) muscle, 481
Chondro-sternal articulation, 222
movements of, 224
Chondro-xiphoid ligament, 224
Chopart's amputation, incision for, 1239
Chorda [xopon a cord] tympani, 808
Chordæ tendineæ, 969, 971
Chorio-capillaris, 877, 882
Choroid [xóptov = the chorion; eldos-like: from
its vascularity], the, 880, 882
artery, anterior, 533
posterior, 544
plexuses, 738, 744, 757
vein, 662
Ciliary [cilium = an eyelash], 889
arteries, 532, 888
of lachrymal, 531, 889
body, 882
ganglion, 797, 901
muscle, 881, 882
nerves, long, 797, 886
short, 797, 886, 901
processes, 881
veins, anterior and posterior, 664
lower posterior, 665
zone of iris, 877
Cingulum [= a girdle] of gyrus fornicatus, 729,
734, 786
of teeth, 94
Circle of Willis, 535
Circular sinus of cranium, 659
inferior (of Winslow), 659
Circulation, foetal, course of, 977
Circulus iridis, major et minor, 888
Circumduction [circum = around; duco = I lead],
189
Circumference of average skull, 93
Circumflex [circum around; flecto= I bend]-
artery, anterior, 557; variations, 557
external, 619; variations, 619
internal, 619; variations, 620
posterior, 557; variations, 558
iliac, deep, 613; variations, 613
superficial, 618
nerve, 835
vein, iliac, deep, 687; superficial, 669, 685
Circumflexus palati muscle, 35, 981
Circumvallate [circumvallatus =trenched
around] papillæ of tongue, 921
Cistern of Pecquet, or receptaculum chyli, 698
Cisterna magna of cranial meninges, 716
pontis, 717
Clarke's column of spinal cord, 778
Claustrum [claudo = I shut], the, 740
Clava [a club], the, 762; nucleus of, 766
Clavicle [dim. of clavisa key: from its shape],
the, 118
blood-supply and ossification of, 119
Clavicular artery of acromio-thoracic, 555
canal, 118
Clavi-pectoral fascia, 308
Cleft sternum, 116
Cleido-hyoid muscle, 487
Cleido-occipital [Kλeis a key; eldos =
muscle, 475
Cleido-occipitalis muscle, 487
1=
like]
Clinoid [Kλivna bed; eloos = like: from their
resemblance to the four posts of a
bed] processes, anterior, middle, and pos-
terior, 32, 92
1=
COM

Clitoris [Kλeiw= I shut up], the, 1078
dorsal artery of, 611
nerve of, 858
Clivus [= a slope], the, 93
Cloaca [a sewer], the primitive, 1092
Cloquet, canal of, 886
Coats of eyeball, inner or nervous, 884
middle or vascular, 882
outer or fibrous, 881
of Fallopian tube, 1089
of intestine, large, 1005
small, 1003
of stomach, 998
Coccygeal aorta, see Middle sacral artery
artery, 607
cornua, 18
glomerulus [dim. of glomus = a ball of
thread], 958
nerve, 854
primary divisions of, anterior, 854
plexus (nerve), 854
posterior, 828
vertebræ, 15, 18; ossification of, 24
Coccygeus muscle, 1100; nerve to, 853
1=1
Coccyx [KOKKU a cuckoo: from its fancied
likeness to a cuckoo's beak], 18
ossification of, 24
Cochlea [kóxλos = a shell fish], 44, 917
Cochlear nerve, 813
Coeliac [Koixia = the belly] artery (= axis), 588;
topography of, 1150; variations, 589
lymph glands, 701
plexus, 870
Colic [kWλov- the large intestine] area of
anterior surface of kidney, 1046
arteries, left, 596; middle, 593; right, 593
Collateral arteries, digital, of fingers, 571
eminence, 731
of toes, 631
intercostal, 582
fissure, 728, 731
Collecting tubes of kidney, 1048
Colles, fascia of, 1103
Colliculus [dim. of collis - a hill] seminalis,
1074
=
Colon [@λov=the large intestine], 1008
ascending, 1008
blood-supply of, 1012
descending, 1009
nerves and lymphatics of, 1012
sigmoid flexure of, 1009
structure of, 1012
transverse, 1009
Colotomy, lumbar, landmarks for, 1148
Columella, the, 917
Columnæ Bertini, 1047
carneæ, 968, 971
rugarum of vagina, 1081
Columns of cord, Burdach's, 782
Clarke's, 778
Goll's, 782
of medulla, lateral, 761
Comes a companion] nervi ischiadici, 608
=
mediani, 566
phrenici, 548
Commissura [con = together; mitto = I send]
mollis, 746
Commissuræ ad flocculos, 757
Commissural branches of anterior cerebral
artery, 534
1264
INDEX
COM
Commissure [= union] of cerebellum, great
anterior, 784
of cerebrum, anterior (white) 742, basal
(grey) 748, middle (grey) 745, pos-
terior (white) 745, 748, 784
Gudden's, 791
Meynert's 791
optic, 749, 790; fibres of, 790
of vagina, posterior, 1076
Common bile duct, 1021
carotid arteries, 505; branches and varia-
tions, 509; collateral circulation after
ligature, 509
femoral artery, 613; variations, 616
vein, 686; variations, 686
iliac artery, 598; collateral circulation,
600; variations, 599
veins, 672; variations, 673
pelvis of kidney, 1051
Communicans peronei nerve, 859
tibialis nerve, 861
Communicantes hypoglossi, 832
Complexus muscle, 446
Compressor narium muscle, 459, 929
minor muscle, 930
sacculi laryngis muscle, 949
urethræ muscle, 1106
vaginæ muscle, 1107
venæ dorsalis penis muscle, 1072
Conarium [conus = a fir cone] or pineal body,
747
Concha [kóyxn= a shell], the, 908
Conductor sonorus, of fourth ventricle, 78, 812
Condylar lines, inner and outer, of femur, 167
ridge, external, 126
Condyle [kóvduhλos = knuckle], tertiary occipital,
29
of basi-occipital, 30, 82
of femur (internal and external), 157;
surgical anatomy of, 1222
of humerus, internal (ulnar), 129
external (radial), 129
of mandible (lower jaw), 69; neck of, 70
miniature, of phalanges (finger), 146
Condyloid [kóvduλos a knuckle; eldos
foramen, anterior, 29, 82, 92, 104
posterior, 30, 82
=
centre of ossification of mandible, 71
fossa, posterior, 30
tubercle of mandible, 70
Conical, or filiform, papillæ of tongue, 922
Conjoint tendon, 431
like]
Conjugate diameter of pelvis, 155; measure-
ments of, 156
Conjunctiva [con= together; jungo
ocular, 876
palpebral, 875, 904
surgical anatomy of, 1120
Conjunctival sac, 877
=
I join],
Connective tissue, central, of orbit, 903
subaponeurotic, of scalp, 115
subperitoneal, 994
Conoid [k@vos a cone; eldos like] ligament,
231
=
Constrictor muscles, of nose, 929
of pharynx, 985
vaginæ muscle, 1079
Conus arteriosus [K@vos a cone], 490, 968
medullaris, 774
vasculosus, 1065
=
=
COR
Convolutions [con together; volvo I roll]
of cerebrum, Broca's, 725
dentate, 732, 739
frontal, ascending, 724; inferior, 725;
middle, 724; superior, 724
infra-marginal, 729
marginal, 731
occipital, inferior, 728; middle, 728;
superior, 728
orbital, anterior, 725; internal, 725; pos-
terior, 725
parietal, ascending, 726
straight, 725
supramarginal, 726

temporal, inferior, 729; middle, 729;
superior, 729; transverse, 729
Coraco-acromial ligament, 232
Coraco-brachialis muscle, 321; nerve to, 837;
surgical anatomy of, 1184
Coraco-clavicular ligament, 231; origin from
subclavius, 295
union, arterial and nerve supply and move-
ments of, 232; ligaments of, 231
Coraco-humeral ligament, 235
=
=
origin from pectoralis minor, 295
Coracoid [kópata raven; eldos like: from a
fancied resemblance to a raven's beak]
(or transverse) ligament, 233
process, 122
Cord, gangliated, of sympathetic, 864; cervical
and cranial portion of, 864; lumbar and
sacral, 869; thoracic (dorsal), 868
genital, 1094
spermatic, 1068; constituents of, 1068
spinal, 771; deep origin of nerves of, 778;
external characters, 774; internal struc-
ture, 776; meninges of, 772; tracts of,
779
Cornea [corneus = horny], the, 881
lymphatic spaces of, 889
Cornicula [dim. of cornu = a horn] laryngis, or
cartilages of Santorini, 942
Cornu [a horn] Ammonis (from its likeness
to the horns on the statue of Jupiter
Ammon), or hippocampus major, 737
Cornua, coccygeal, 18
of fascia lata of thigh, 1166
of hyoid bone, 73; centres of ossification
for, 103
of lateral ventricles, anterior and posterior,
736; inferior or descending, 737
sacral, 16
of thyroid cartilage, inferior and superior,
940
Corona [ a crown] ciliaris, 882

glandis, 1071
of the optic thalamus, 784
radiata, the, 785
Coronal [corona = a crown] section of brain, 710
suture, 50
of skull, 89
Coronary arteries [corona = a crown or circlet :
so called because they encircle the
heart] of heart-
left, course and branches, 503, 973
right, course and branches, 502, 972
variations of, 503
of stomach, 589
branches and variations, 590
of lips, inferior, 517; superior, 518
INDEX
1265
COR
Coronary ligaments of knee, 272
of liver, 1019
plexus, right and left, 870, 977
sinus, 646, 967, 974
vein, cardiac, 646, 973; anterior and pos-
terior, 647, 974; great, 646, 973;
smallest, 648
gastric, 674
labial, 651
Coronoid centre of ossification for mandible,
71
fossa of humerus, 129
process of mandible, 70, 1122
of ulna, 131
Corpora [plural of corpus a body] albicantia
=
[albico I become white], 742, 748
=
clitoridis, 1107
quadrigemina
[quadrigeminus
placed in two pairs], 749, 751
Corpus [= a body] Arantii, 969
callosum [callus = hard], 709, 733
=
four,
cavernosum [caverna a cavern], 1070;
artery of, 611, 1104
=
dentatum [dentatus = toothed], 756
fimbriatum [fimbria = a fringe], 738
geniculatum [dim. of genu] externum, 752;
internum, 751
Highmorianum, 1064
luteum [=yellow], 1091
spongiosum [spongia = a sponge], 1070
striatum [stria a streak], 739
trapezoides [Tрárea = a table; eldos = like],
812
Corrugator [corrugare = to wrinkle] supercilii
muscle (the muscle that wrinkles the
eyebrows), 457
Cortex [the rind] of kidney, 1047
of lens, 886
of olfactory tract, 788
Cortical arteries, of kidney, 1049
hemispheral, of anterior cerebral, 534
of middle cerebral, 535
of posterior cerebral, 544
veins of brain, superior and inferior, 661
Cortico-medullary arches of kidney, 1048
Costal [costa a rib] cartilages, 110
Costo-central articulation, arterial and nerve
supply of, 221
ligaments of, 219
movements of, 221
Costo-cervical artery (= superior intercostal),
550
Costo-chondral articulation, 224
Costo-clavicular (rhomboid) ligament, 228
Costo-coracoid ligament, origin of, 124
membrane, 308
Costo-fascialis muscle, 487
Costo-transverse articulation, arterial and nerve
supply of, 222
ligaments of, 221
movements of, 222
Costo-vertebral groove, 117
Cotunnius, nerve of, 800
Cotyloid [korúan a cup; eldos = like] bone, 153
cavity (acetabulum), 148, 153
foramen, 153
notch, 153
Cowper's glands, 1106; development of, 1095
Cranial [kpavíov = the skull] fossa, anterior, 89;
middle, 92; posterior, 93
CRU
Cranial nerves. 786; general distribution,
788
superficial and deep origins of, 788
sinus, definition of, 711
sinuses, venous, 656.
individual sinuses
See also Sinus, for
Cranio-cerebral topography, 766
Cranio-facial angle, 88; measurement of, 93
Cranio-pharyngeal canal, 32; at birth, 101
Cranium [kpavíov = the skull], capacity of, ave-
rage, 93
cartilaginous the, 97; remnants of, 103
measurements of, average, 92, 93
membranous, the, 97
results of elasticity of, 1116
structure of, 1116
Cremaster [Kрeμάw I suspend: from its action
=
on the testis] muscle, 432
Cremasteric artery of deep epigastric, 612
of spermatic, 595
fascia (or middle spermatic), 1061
Crest, falciform, 39
of ilium (iliac), 149
malar, of sphenoid, 34
obturator, 153

occipital, external, 26; internal, 27, 93
of pubes, 152
of scapular spine, 122
sphenoidal, 32
supramastoid, 37
of tibia, 163
turbinated, inferior and superior, 62
Cribriform [cribrum = a sieve] area, middle and
superior, 39
fascia, 365
plate of ethmoid, 53
tract, spiral, 39
Crico-arytenoid joints, 944
(or transverse) ligament, 944
posterior, 944
Crico-arytenoideus lateralis muscle, 945
posticus muscle, 945
Crico-thyroid artery, 513
joints, 944
membrane, 943
muscle, 945

Cricoid [píkos = a ring; eidos = like] cartilage,
943
Crista [a crest] vestibuli, 44
=
galli [gallus a cock], 53, 92
Crown, of teeth, 94; relation of upper to lower
tooth crowns, 96
Crucial [crux= a cross] anastomosis of femur,
607, 619
ligament of central atlanto-axoidean joint,
197
of knee joint, 270
ridges of occipital bone, 27
Crura [crus, pl. crura = leg] cerebri, 752

of diaphragm, 424
of facial nerve, 806
of stapes, 75

Crural arch, 1166; deep, 436, 1167
nerve, anterior, 851
of genito-crural, 849
septum, 1167
Crureus muscle, 388
Crus, artery of the, 611
clitoridis, 1078
penis, 1070
4 M
1266
INDEX
CRU
DOR
Crusta [the rind, or crust], the, of crura
cerebri, 752
Crystalline lens, the, 881
Cubo-cuneiform joint, arterial and nerve supply
and movements of, 286
ligaments of, 286
Cubo-metatarsal joint, 291
Cubo-scaphoid joint, arterial and nerve supply
of, 286
ligaments of, 285
movements, 286
Cuboid [kúßos = a cube; eldos = like], the, 176
articulations, ligaments, attachment of
muscles, and ossification, 176
=
Culmen [= a roof], the, of cerebellum, 754
Cuneate [cuneus a wedge] lobule of cerebrum,
732
Cuneiform [cuneus a wedge] bone, carpal,
140; ossification, 143
tarsal, external, 178; ossification, 179
internal, 177; ossification, 177
middle, 177; ossification, 178
cartilages of Wrisberg, 943
Cuneus [= a wedge], or cuneate lobule of cere-
1=
brum, 732
Cupula [a vault] of cochlea, 918
Curvator coccygis muscle, 487
Cushion of the epiglottis, 942
Cystic [KUOTIS = a bladder or bag] artery, 591
duct, 1021
plexus (nerve), 871
vein, 674
DARTOS [Saprós = flayed] of penis, 1070
of scrotum, 1060
Date of ossification of bones of foot, 185
of hand, 143
Declive, the, of cerebellum, 754
Decussatio lemnisci [Anuvio kоs=a band], 765
Deferential artery (= artery to vas deferens), 604
Deiter's nucleus of auditory nerve, 812
Deltoid [déλra = the letter A; eidos like: from
its shape] ligament of ankle, 280
muscle, 316; surgical anatomy of, 1183
tubercle, 118
=
Dental [dens a tooth] artery, anterior, 527
inferior (or mandibular), 525
posterior, 526
canals, anterior, 61, 84, 105
formula, adult, 94; temporary, 96
nerves, inferior (= mandibular), 804
superior, 799
veins, inferior (= mandibular), 653.
posterior, 653
Dentary centre of ossification in mandible, 71
Dentate convolution, 732, 739
fascia (= convolution), 732, 739
fissure, 731
Depression for Gasserian ganglion, 92
lateral, of middle fossa basis cranii, 92
rhomboid, of clavicle, 119
Depressor alæ nasi muscle, 460, 930
anguli oris muscle, 465
labii inferioris muscle, 467
thyroidea muscle, 488
Descemet's membrane, 882
Descendens hypoglossi nerve, 821
Descending branch of external circumflex
artery, 619
Descending branches of cervical plexus, 831
of Meckel's ganglion, 801
colon, 1009
cornu (inferior) of lateral ventricle, 737
palatine arteries, 527
pharyngeal arteries, 527
ramus of pubes, 151
root of optic nerve, 791
of trigeminal nerve, 794
Development of genito-urinary organs, 1092.
For bones, see Ossification, centres of
Diameters of pelvis, 155
Diaphragm [Siappayua = a partition], the, 423
openings in, 424
surgical anatomy of, 1144
Diaphragma sellæ, 712, 715
Diaphragmatic arteries of aortic intercostals,
583

lymphatics, 696
plexus (nerve), 871
=
Diarthrosis [diá = between; apepov a joint],
definition and examples of, 187
subdivisions of, 187
Digastric [8is twice; yaorhp = belly] fossa, 68
=
groove, 40, 84
muscle, 478
tendon, 479
Digestion, organs of, 979
Digital arteries of fingers of palmar arch, 570
collateral, 571
dorsal, 575
of toes, collateral, 631
dorsal, of dorsal interosseous,
636
of dorsalis hallucis, 637
plantar (communicating), of
dorsalis pedis, 637
of external plantar, 630
fifth (=princeps polli-
cis), 637
superficial, of internal plantar,
632
fossa of tunica vaginalis, 1063
nerves of toes, 863
of fingers, 842
phalanges of foot, 183
of hand, 146
veins of foot, 683
of hand, 679


Dilatator naris anterior muscle, 460, 929;
posterior muscle, 461, 929
Dimensions of kidney, 1042
of ovaries, 1090
of uterus, 1084
Diploë [STAóos = double], veins of, 655
Diploic artery, 531
Direction of inguinal canal, 1161
of uterus, 1084
Disc, optic, 877
Distal row of carpus, bones of, 137
surface (of tooth), 94
Diverticulum [diverto= I turn aside], Meckel's,
1003
Dorsal artery of clitoris, 611
of penis, 611, 1104
branch of aortic intercostal artery, 582
of ulnar (=posterior) nerve, 840
digital arteries of fingers, 575
of toes, 636
integument of hand, nerve-supply of, 842
INDEX
1267
DOR
EPI
Dorsal interosseous arteries of foot, 636
of hand, 574
nerve of clitoris, 858
of penis, 850, 1106
(or thoracic) vertebra, peculiar, 13
typical, 12
scapular artery, 556
spinal plexus (venous), 667
vein of penis, 677
Dorsalis hallucis artery, 636
indicis artery, 576
venous plexus of hand, 679
linguæ artery, 514
pedis artery, 634; surgical anatomy of, 1242
pollicis artery, 576
Dorso-epitrochlearis muscle, 488
Dorsum ephippii [épíπTIov a saddle], 32, 92;
at birth, 101
ilii, 148
of scapula, 120
of tongue, 921
Douglas, fold of, 435
pouch of, 1080, 1083
Duct, common bile, 1021
cystic, 1021
=
ejaculatory, 1067; orifice of, 1074
of Gartner, 1080, 1087, 1093
hepatic, 1021
lachrymal, 61, 84
Müllerian, 1094
nasal, 61, 84, 906
of pancreas, 1024
of parotid, 984; surgical anatomy of,
1119
renal (= ureter), 1051
Rivini's, 984
of sublingual gland, 984
Wharton's (= submaxillary), 984
Wolffian, 1092
Ducts, galactophorous [yáλa = milk; pépw=I
carry] (lactiferous) [lac = milk; fero
= I bear], 1109
Ductus [duco I lead] arteriosus (= Botalli),
=
491, 962, 977
cochlearis, 920
communis choledochus
Séxouai I receive], 1021
=
endolymphaticus, 39
perilymphaticus, 39,
83
[χολή = bile ;
venosus, 673, 978; fissure of, 1015
Duodenal fold, evolution of, 1040
Duodenum [duodeni = twelve], the, 1000
Dura [= hard] mater [= mother], the, of brain,
711
of spinal cord, 772; differences between
it and cranial dura mater, 772
EAR, the external, 907; ligaments and muscles
of, 908; vessels and nerves of, 909
internal, 916
middle, 911. See Tympanum
veins of the, 663
Ear-shaped cartilage of sacro-iliac joint, 212
Ehrenritter, ganglion of, 814
Eighth cranial (auditory) nerve, 811; roots,
811; branches, 813
Ejaculatory duct, 1067; orifice of, 1074
Elastic fibres (yellow) of trachea, 952
lamina (posterior) of cornea, 882
Elasticity of cranium, results of, 1116
Elbow, arrangement of superficial veins in
front of, 1191
hollow in front of, 1191
surgical anatomy of, 1188
Elbow joint, anastomoses round, 1191
arterial and nerve supply and move-

ments of, 241
ligaments of, 239
Eleventh cranial (spinal accessory) nerve, 819
rib, 110

Eminence, articular, 38, 77
canine, 60
frontal, 50, 84
nasal, 50
olivary, 32, 92
parietal, 48
Eminences, hypothenar, muscles of, 363
surgical anatomy of, 1199
thenar, muscles of, 358
surgical anatomy of, 1199
Eminentia articularis, 38, 77
collateralis, 731, 737
teres, 758

Emissary veins of cranium, 711
of scalp, 1116
Emulgent [emulgeo= I drain out] or renal
arteries, 594
veins, 670
Enarthrodia [èv in; apopov = a joint], defini-
=
tion and examples of, 188
1=
Encephalon [èv=in; kepaλ= the head], the,
718; grey and white matter of, 718
Endocardium [evdov within; kapdía
heart], the, 966
=
=
the
Epencephalon [èπí = upon; кepaλn the head],
the, 709, 753
Ependyma [êrí; ěvovua = clothing], the, 710
Epicerebral spaces, 718
Epicranial [èí = upon; pavíov = the skull] apo-
neurosis, 454
Epididymal artery, 596
Epididymis [ení = upon; didumos = the testicle],
the, 1063
tube of, 1065
Epigastric [ení upon; yaoтhp = the stomach]
artery, deep, 612; variations, 613
superficial, 618
superior, 550
lymphatic glands, 696
vein, deep, 687; superficial, 669, 685
Epiglottis [ení upon; yλwTTís = the glottis],
the, 941; cushion of the, 942
Epiotic [èrí upon; ous, gen. wrós- the ear]
=
centre of ossification, 47
=
Epiphyses [èrí upon; púw I grow], rules
concerning, 3
unossified (costal cartilages), 110
Epiphysial cartilages, 1
lines, 1
Epiphysis cerebri (= pineal body), 747
Epiploic [èní upon; Tλéw = I sail] (ascending
omental) artery of right gastro-epiploic,
591
=
(descending omental) artery of left gastro-
epiploic, 592
Epipteric [ení = upon; Tréput = a wing] ossicle,
78
Epispinal spaces, 718
Episternal bones, 113
4 M 2
1268
INDEX
ΕΡΙ
FAS
=
Epithelium [ení upon; enλ = papilla], germi-
nal, 1094
subcapsular, 886
Epitrochleo-anconeus muscle, 488
Equator of eyeball, 878
Erector [erigere = to raise] penis (=ischio-
cavernosus) muscle, 1072
spinæ muscle, 441
Ethmoid [houós = a sieve; eldos = like: from
the perforations in its horizontal plate]
bone, 53; ossification, 55
at birth, 102
Ethmoidal arteries, anterior and posterior,
532
canals, 50, 54, 85, 92, 104
cells, 55, 87
fissure, 54, 92
foramina, 54, 92
grooves, 54
notch, 50
spine of sphenoid, 32, 92
veins, anterior and posterior, 664, 934
Ethmo-lachrymal suture, 85
Ethmo-sphenoidal suture, 92
Ethmo-turbinals, 54
Ethmo-vomerine region of chondral skull, 97
plate (at birth), 103
Eustachian arteries of pterygo-palatine, 527
of Vidian, 527
tube, 913
valve, 966; in fœtus, 977
Evolution of peritoneum, 1028
Ex-occipital bones, 26; at birth, 100
Excretory duct of kidney, 1051
Extensor [extendo- I stretch out] annularis
muscle, 488
brevis digitorum muscle, 415
manus muscle, 488
pollicis muscle, 349
carpi radialis brevior muscle, 341
accessorius muscle, 488
longior muscle, 341; nerve to, 841
ulnaris muscle, 345
coccygis muscle, 488
communis digitorum muscle, 342
indicis muscle, 350
longus digitorum muscle, 412
pollicis muscle, 349
medii digiti muscle, 488
minimi digiti muscle, 344
ossis metacarpi pollicis muscle, 348
metatarsi hallucis muscle, 488
primi internodii hallucis longus muscle,
488
proprius hallucis [proprius = belonging
to; hallux= great toe] muscle, 411.
Exterior of the skull, 75
Extraspinal veins, 667
Extrinsic [extrinsecus = outward] muscles of
auricle, 908
of larynx, 945
of tongue, 925
Eye, the, 874
Eyeball, the, examination of; 878
equator of, 878
general surface view of, 874
Eyelids, the, 875, 902
blood-vessels of, 904
glands of, 903
lymphatics of, 904
Eyelids, nerves of, 904
surgical anatomy of, 1119
FACE, surgical anatomy of, 1111
Facet [facette a little face], patellar, of femoral
condyle, 160
pyriform, of astragalus, 170
triangular, of astragalus, 171
Facial artery, 515
transverse, 522
bones, 26
lymphatic glands, deep, 692
vessels, superficial, 689
nerve, 806
segment of chondro-cranium, 97, 927
skeleton at birth, 100
vein, common, 650
communicating, 650
transverse, 652; variations, 651
Falciform [falx = a sickle] ligament of fascia
lata of thigh, 365
of Burns, 1166
lobe of cerebrum, 723, 732
process of temporal bone, 39
Fallopian [from Fallopius, the anatomist]
artery, 596
canal, 40, 43, 912
tube, 1086, 1088; position of, 1089;
lymphatics of, 702, 1092; structure of,
1089; vessels and nerves of, 1091
False ligaments of bladder, 1056
ribs, 106
vocal cords, 949
Falx [a sickle: from its shape] cerebelli, 715
cerebri, 714
Fascia [a bundle], anal, 1102
axillary, 308
clavi-pectoral, 308
of Colles, 1103
cremasteric (or middle spermatic), 1061
cribriform, 365
dentate (= dentate convolution of cere-
brum), 732, 739

endothoracic, 423
of the forearm, deep, 327
of groin, superficial, 1165
of the hand, dorsal, 351
palmar, 351; surgical ana-
tomy of, 1206
hypothenar, 352
thenar, 352
of head and neck, deep (cervical), 472
superficial, 452
iliac, 368
of fascia lata of thigh, 1166
infundibuliform (propria), 432, 436, 1061
intercolumnar, 430, 1061, 1159
ischio-rectal, 1102
of the leg, deep, 390
lumbar, 433, 1176
masseteric, 468
of muscles from scapula to upper limb,
superficial and deep, 315
of muscles passing from trunk to upper
extremity, anterior division (super-
ficial), 308
posterior division (superficial and
deep), 302
obturator, 1098
INDEX
1269
Fascia, orbital, 894
FAS
palmar, 351; surgical anatomy of, 1206
palpebral, 894
parotid, 468
pectoral, 308
pelvic, surgical anatomy of, 1156
perinæal, 1103
plantar, 399
prevertebral, 473
propria (infundibuliform), 432, 436, 1061
pubic, of fascia lata of thigh, 1169
recto-vesical, 1056, 1101
spermatic, external, 430, 1061, 1159
internal and middle, 1061
temporal, 468
of the thigh, deep (fascia lata), 364, 1166
superficial, 364
tibial, deep, 396
transversalis, 436
triangular, of external oblique, 429
of the upper arm, deep, 321
Fascia of orbit, 893
pelvic, 1098
Fascial sheath of penis, 1070
Fasciculus (dim. of fascia) arcuatus, 786
garland-like, of cerebellum, 784
longitudinalis, inferior, 786
oblique, of pons, 760
perpendicular occipital, 786
teres of fourth ventricle, 758
uncinatus, 786
Fasciola [dim. of fascia] cinerea [=grey],
739
Fauces [faux- the throat], the, 979
isthmus of, 980
pillars of, 980
Female bladder, the, 1058
genitals, external, 1076; surgical anatomy
of, 1156
mamma, 1108
development and abnormalities, 1110
variations according to age, &c., 1109
vessels, nerves, and lymphatics, 1110
pelvis, 156
perinæum, 1107
urethra, 1079
Femoral [femur - the thigh] artery, 613
branches and variations, 616
line of, 1213
surgical anatomy of, 1214
deep (profunda), 618
canal, 1167
condyles and tuberosities, surgical ana-
tomy of, 1222
hernia, parts concerned in, 1165
course of, 1168
covering of, 1169
ligament, 1166.
lymphatic glands, deep, 707
ring, 1167
superficial, 705
position of vessels around, 1168
sheath, 1167
vein, 686
common, 686
variations, 686
deep (profunda), 686
Femur [the thigh], the, 156
blood-supply, 161
ossification of, 162
FIS
Fenestra [a window] ovalis, 42, 913, 916
rotunda, 42, 913
Ferrein, pyramids of, 1048
Fibres of medulla, arciform, 762, 783
of cerebellum, 783
of cortex cerebri, intrahemispheric, long
and short, 786
of optic chiasma, 790
of pons Varolii, 670, 783
of trachea (yellow elastic), 952
Fibro-cartilage, cotyloid, of hip, 262
of knee, external, 271


internal, 272
interarticular, of acromio-clavicular joint,
230
of sterno-clavicular joint, 229
of temporo-mandibular articulation, 190
intervertebral, 201
pubic, 218
triangular, of wrist, 243
Fibrous coat of eyeball, 881
layer of pericardium, 962
membrane of trachea, 951
Fibula [a clasp], the, 168
development of, 169
Fifth (trigeminal) cranial nerve, 794
divisions of, ophthalmic, 795
mandibular (= inferior maxillary),
801
maxillary (sup. maxillary), 797
foramen for, 93
Figures, stellate, of lens, 886
Filiform [filum = a thread], or conical papillæ
of tongue, 922
Fillet of crus cerebri, 752, 782
tract of the, 782

Filum [a thread] terminale of pia mater,
774
Fimbria [= a fringe], or corpus fimbriatum, 738,
742
ovarica, 1089
Fimbria [fimbria = a fringe] of Fallopian tubes,
1089
First cervical nerve, anterior primary division
of, 828
posterior primary division of, 826
cranial or olfactory nerve, 788

rib, 108
Fissure [findo = I cleave] of auricle, Santorini's,
908

of bone, auricular, 40, 84
ethmoidal, 54, 92
Glaserian, 38, 83, 105
maxillary, 62
pterygo-maxillary, 77, 85, 105
sphenoidal, 33, 84, 92, 105
spheno-malar, 85
spheno-maxillary, 77, 85, 105
of cerebellum, great horizontal, 754
of cerebrum, calcarine, 731
callosal, 731
calloso-marginal, 730
collateral, 728, 731
dentate, or hippocampal, 731
frontal, inferior and superior, 724
great longitudinal, 721
transverse, 721
hippocampal, or dentate, 731
interlobar, 722
intraparietal, 726
1270
INDEX
FIS
Fissure of cerebrum, occipital, inferior, middle,
superior, and transverse, 727
parallel, 728
parieto-occipital, external and in-
ternal, 722, 731
perpendicular, internal, 722
of Rolando, 722
genua of, 723
origin of, 723
of Sylvius, 722
temporal, inferior and middle, 728
triradiate, 725
genital, female, 1107
of liver, of ductus venosus, 1015
longitudinal, 1016
transverse, or portal, 1016
umbilical, 1014, 1016
for vena cava, 1016
of medulla oblongata, anterior and poste-
rior, 761
prostatic, 1059
of spinal cord, antero-lateral, postero-
lateral, and longitudinal, anterior and
posterior, 776
Flexor [flectere-to bend] accessorius digitorum
pedis muscle, 404
accessorius longus muscle, 488
brevis digitorum pedis, or flexor perforatus
muscle, 401
hallucis [hallux= great toe] muscle,
405
minimi (manus) digiti muscle, 363
pedis digiti muscle, 407
=
pollicis [pollex - thumb] muscle, 360
pedis, or flexor brevis hallucis,
muscle, 405
carpi radialis muscle, 330; nerve to, 838
brevis vel profundus muscle, 488
ulnaris muscle, 331; nerve to, 840
longus digitorum muscle, 396
hallucis muscle, 398
pollicis muscle, 337
ossis metacarpi pollicis muscle, 360
perforatus muscle, or flexor brevis digi-
torum pedis, 401
profundus digitorum muscle, 335; nerve
to, 840
sublimis digitorum muscle, 332; nerve to,
838
tendons of hand, sheaths of (theca), 352
Floating ribs, 106
Floccular fossa, 39
Flocculus [dim. of floccus = a lock of wool], of
cerebellum, 755
Floor of descending cornu of lateral ventricle,
structures in, 737
of fourth ventricle, structures in, 758
of third ventricle, structures in, 746
Fluid, cerebro-spinal, 718
Foetal circulation, 977
heart, peculiarities of, 977
position and weight, 997
skull, general characters of, 98
Fold, aryteno-epiglottidean, 942
of Douglas, 435
duodenal, 1002; evolution of, 1040
glosso-epiglottidean, 921, 942
palpebral, superior and inferior, 875
pharyngo-epiglottidean, 942
semilunar, of conjunctiva, 878
FOR

Fold, vestigial, of pericardium, 963
Folds or creases of palm, surgical anatomy
of, 1199
Folia of cerebellum, 753
Folian or slender process of malleus, 74
Folium [a leaf] cacuminis [cacumen = the
summit] of cerebellum, 754
Follicles [dim. of follis= a bag], Graafian, 1090
Meibomian, 875
Fontanelles [dim. of fons = a fountain],
anterior and posterior, 99
anterior and posterior lateral, 99
Foot, the bones of the, 169
arches of, 1242; keystone of, 1244;
pillars of, 1244
bursæ of, 1241
dorsal artery of, surgical anatomy of, 1242
levels of joints of, 1238
surgical anatomy of, 1238
synovial membranes of, 1241
veins of, 685
Foramen [foro = I pierce] for aorta (in dia-
phragm), 424
auditory (internal auditory meatus), 104
cæcum, 50, 53, 92
anterius, 748
posterius (= of Vicq d'Azyr), 761
of tongue, 921
centrale cochleare, 39
commune anterius, 709, 737
condyloid, anterior, 29, 82, 92, 104
posterior, 30, 82
costo-transverse, of atlas, 9
of cervical vertebræ, 8
of seventh cervical (vertebra pro-
minens), 9
of typical vertebra, 7
dental, inferior (mandibular), 69, 105
ethmoidal, 54, 92
explanation of term, 5
for fifth cranial nerve, 93
infra-orbital, 60, 105
for internal carotid artery (occasional), 93
jugular, 83, 93, 104
lacerum medium, 82, 92
for lesser petrosal nerve, 39, 93
magnum, 29, 82, 93, 104
of Majendie, 758
mandibular (inferior dental), 69, 105
mastoid, 84, 93
mental, 68
obturator, 148, 153
for oesophagus (in diaphragm), 424
optic, 32, 84, 92, 104
ovale, 33, 77, 92, 104
of foetal heart, 977
valve of, 977
palatine accessory, anterior and external, 79
parietal, 49
petro-sphenoidal, 38, 92, 104
rotundum, 33, 77, 92, 104
sacro-sciatic, great and small, 213
scleræ, 881
singulare, 39
spheno-malar, 78, 85, 105,
spheno-palatine, 65, 77, 87, 105
sphenotic, 82, 92
spinosum, 33, 77, 92
stylo-mastoid, 40, 84, 105
supra-orbital, 50
Hoold
INDEX
1271
FOR
Foramen, suprascapular, 122
supratrochlear, 129
for third cranial nerve, 93
thyroid [0úpa = an opening] (obturator),
148, 153
trigeminal, 38, 104
for vena cava (inferior in diaphragm), 424
Vesalii, 33, 92
of Winslow, 990
Foramina of skull, primary nerve foramina, 104
secondary n. foramina, 104
transmitting brs.of facial n.,105
of Key and Retzius, 750
papillaria, 1047
of fifth n., 104
sacral, anterior and posterior, 16
Scarpa's, 62, 79, 105
spinal, 8
Stenson's, 79
Thebesii, 960, 967
Forceps, major, of corpus callosum, 729, 735
minor, 729, 734
Forearm, cutaneous nerves of, 1197
muscular prominences of, 1195
surgical anatomy of, 1193
Formatio reticularis, 760, 764, 778
Fornix [= an arch], the, 742
conjunctival, 876
Fossa [= a ditch or depression]--
of antihelix, 908
of base of skull, anterior, 89
canine, 60
middle, 92
posterior, 93
condyloid, posterior, 30
coronoid, 129
digastric, 68
digital, of tunica vaginalis, 1063
duodeno-jejunalis, 1002
floccular, 39
of gall bladder, 1014
glenoid, 38, 83
of helix, 908
ileo-cæcal, 1007
iliac, 148
incisive, of mandible, 68
of maxilla, 60
infraspinous, 121
innominata, of larynx, 949
intersigmoid, 1011
ischio-rectal, 1102, 1153
contents of, 1103
jugular, 39, 83
lachrymal, 51, 84
malleolar, of fibula, 168
nasal, 86
navicularis, of urethra, 1075
olecranon, 129
ovalis, of auricular septum, 968
palatine, anterior, 62
pituitary, 32
pterygoid, 35, 79
scaphoid, 35, 79
of auricle, 908
sigmoid, greater, 131
lesser, 132
spheno-maxillary, 77
sublingual, 68
submaxillary, 69
subscapular, 120
GAN

Fossa, supraspinous, 121
supratrochlear, 51
Sylvii, 722, 729
temporal, 76
triangular, of auricle, 908
trochanteric, 157
vermiform, 27, 93
zygomatic, 76
Fossæ, adipose, of female breast, 1108
on posterior surface of abdominal parietes,
1163
Fossula [dim. of fossa] cochlearis, 39
vestibularis, 39
Fourchette [= a fork] of vagina, 1076
Fourth or trochlear cranial nerve, 900
sacral nerve, 853
Fovea [=a pit] centralis of retina, 878, 884
hemielliptica, 44, 916
hemispherica, 44, 916
inferior and superior, of fourth ventricle, 758
Frænum [a curb or bridle], artery of, 515
epiglottidis, 921
linguæ, 921
præputii, 1069
Frenulum [dim. of frænum] veli, 751
Frontal [frons, frontis forehead] artery, 533
of anterior etmhoidal, 532
bone, 50; ossification of, 52
at birth, 101
convolutions of cerebrum, 724
eminence, 50, 84
fissures of cerebrum, 724
lobe of cerebrum, 724
nerve, 796, 901
pontine tract, 785
process of malar bone, 67
sinuses, 51, 1113; development of, 52
vein, 649
of diploë, 655
Frontalis muscle, 455
Fronto-ethmoidal cells, 55
suture, 92
Fronto-nasal plate of chondro-cranium, 97
Fronto-parietal vein of diploë, 656
Fronto-sphenoidal vein of diploë, 655
Fronto-squamosal suture, 40, 78
Fundus [= the bottom] of uterus, 1083
Fungiform [fungus = a mushroom] papillæ of
tongue, 922
Funicular [dim. of funis a cord] artery, 1088,
1092
=
Funiculus [dim. of funis a cord], anterior, of
medulla, 761
cuneatus, 762
gracilis, 762
solitarius, 813
=
Furrow, median, of back, 1170
squamo-mastoid, 40
Furrowed band, 755
GALACTOPHOROUS [yáλa = milk; pépw= I carry]
or lactiferous ducts, 1109
Galen, vein of, cardiac, 647, 974
cerebral, 662, 743
Gall bladder, the, 1020
fossa of, 1014
structure of, 1022
topography of, 1146
Ganglia [yayyλLov a swelling], basal cranial,
739
1272
INDEX
GAN
Ganglia, cranial, of sympathetic, 864
of glosso-pharyngeal nerve, 814
lumbar, 869
mesenterica, 871
of pneumogastric nerve, 817
prostatica, 873
sacral, 869
semilunar, 870
of spinal nerves, 822
of sympathetic nerves, 864
thoracic, 868
Gangliated cords of sympathetic, 864
cervical portion, 864
cranial portion, 864
lumbar portion, 869
sacral portion, 869
thoracic portion, 868
Ganglion [yayyλlov an enlargement]-
Andersch's, 814
=
Arnold's, or otic, 805
Bochdalek's, 799
cervical, inferior, 865
middle, 867
superior, 865
ciliary, or lenticular, 797, 901
diaphragmaticum, 832, 871
Ehrenritter's, 814
Gasserian, 39, 795; depression for, 92
geniculate, 807
impar [= unequal],
869
intercaroticum, 507
jugular, 814
lenticular, 797, 901
Meckel's, or nasal, 800
ophthalmic, or lenticular, 797, 901
otic, 805
petrous, 814
of pneumogastric, root, 817
trunk, 817
spheno-palatine, or Meckel's, 800
stellatum, 868
sublingual, 805
submandibular, or submaxillary, 805
Valentin's, 799
of Wrisberg, cardiac, 975
Ganglionic artery, of anterior cerebral, 534
of middle cerebral, 534
of posterior cerebral, 544
veins, 662
Gartner, duct of, 1080, 1087, 1093
Gasserian artery, of middle meningeal, 524
branches of carotid plexus, 865
ganglion, 39, 795
=
Gastric [yaorhp- the stomach] area of anterior
surface of kidney, 1046
artery (coronary), 589; variations, 590
of gastro-epiploic, left, 592
right, 591
lymphatic glands, inferior, 703
superior, 702
lymphatics, inferior and superior, 702
nerve plexus, 871
vein, 674
Gastrocnemius [yaorhp the belly; кvμn = the
calf] muscle, 391; variations, 393
Gastro-duodenal yaσrhp = the belly; duo-
denum] artery, 590
=
Gastro-epiploic [yaorhp- the belly; éπíπλoov =
the omentum] artery, left, 592
right, 591
GLA

Gastro-epiploic lymphatic glands, 703
nerve plexus, left, 870; right, 871
vein, left, 676; right, 675
Gastro-hepatic, or lesser omentum, 993
evolution of, 1036
Gastro-phrenic [pphy-diaphragm] ligament,
994
Gastro-splenic omentum, 994
evolution of, 1040
Gemellus [= a twin] inferior muscle, 378;
variations, 379
superior muscle, 377; variations, 378
Genial [yéveLov=the chin] tubercles, 68
Geniculate [dim. of genu= a knee] ganglion, 807
Genio-hyo-glossus [yévetov = the chin; voedŃS
= the hyoid bone; yλ@ora = the tongue]
muscle, 481; nerve to, 822
Genio-hyoid [yévelov - the chin; voeds = the
hyoid bone] muscle, 480; nerve to, 821
Genital branch of genito-crural nerve, 849
cord, 1094


fissure in female, 1107
gland, 1094
Genitals, external, development of, 1094
female, 1076
male, 1058
Genito-crural nerve, 848
Genito-urinary organs, development of, 1082
Genu of corpus callosum, 733, 734
of inner capsule, 741
nervi facialis, 806
Genua [genu= a knee] of fissure of Rolando,723
Germinal epithelium, 1094
Gimbernat's ligament, 430, 1166
Gingival [gingiva = the gums] arteries of pos-
terior dental, 526
Ginglymo-arthrodial joints, 188


=
Ginglymus [viyyλuuosa door hinge], 188
Giraldès, organ of, 1065, 1093
Girdle, pectoral, morphology of, 124
Glabella [dim. of glaber, fem. glabra = smooth],
50, 88, 767
Gladiolus [dim. of gladius=a sword] sterni,
112
Gland, carotid, 507
genital, 1094
lachrymal, 904
mammary, of female, 1108
development and abnormalities, 1110
variations according to age, &c., 1109
vessels, nerves, and lymphatics, 1110
of male, 1109
parotid, 982
thymus, 955
thyroid, 952
Glands of Bartholin, 1077, 1107
of Brunner, 1004
of Cowper, 1106
of eyelids, 903

lymphatic, see Lymphatic glands
of Nuhn, 923
salivary, the, 982
of soft palate, 982
solitary, of intestine, 1004
Glandular (or submaxillary) artery, 517
vein, 651
Glans [=an acorn] clitoridis, 1078
penis, 1069, 1071
Glaserian artery, 524
fissure, 38, 83, 105
INDEX
1273
GLE
Gleno-humeral bands, 235
ligament, 235; origin from subclavius, 295
Glenoid [yλhun a shallow socket; eldos = like]
=
cavity of scapula, 122
fossa, 38, 83
fossæ of finger phalanges, 146
of toe phalanges, 183
ligament of interphalangeal joints of foot,
294
of interphalangeal joints of hand, 258
of metacarpo-phalangeal joints, 256
of shoulder joint, 235
lobe of parotid gland, 983
Glisson's capsule, 1020
Globus [a ball] major et minor, 1062
pallidus, 740
Glosso-epiglottidean [yλ@ooathe tongue; èní
= upon; yλwTTís] folds, 921, 942
pouch, 921
=
Glosso-pharyngeal [yλwooa- the tongue; páp-
vy pharynx] or ninth cranial nerve,
813
branches, 814; roots, 813
communicating branch from superior
cervical ganglion to, 814, 867
from vagus to, 814, 817
Glottis [yλwTTís = the mouthpiece of a wind
instrument], the, 947.
See Larynx
Gluteal [youtós = the buttock] artery, 602;
topography of, 1219
inferior, 607
lymphatics, 700, 705
nerves, inferior, 855
ags superior, 854
ridges of femur, 157
of ilium, 148
veins, 677
Gluteus [YouTós the buttock] maximus
=
muscle, 371; surgical anatomy of, 1217
medius muscle, 374
minimus muscle, 374
quartus muscle, 488
Gonion, the, 88
Gower's tract of spinal cord, 781
Graafian follicles, 1090
Gracilis [gracilis = slender] muscle, 383
Great auricular nerve, 830; topography of,
1130
cardiac vein, 973
deep petrosal nerve, 800, 865
horizontal fissure of cerebellum, 754
longitudinal fissure of cerebrum, 721
occipital nerve, 827
omentum, 993; evolution of, 1037;
length of, 993
(anterior) palatine nerve, 801
palmar bursa, 334
prevertebral plexuses, 869
(posterior) sacro-sciatic ligament, 212;
origin from biceps femoris, 295
falciform process of, 210
sciatic nerve, 858; topography of, 1219
splanchnic nerve, 868
superficial petrosal nerve, 800
toe, incisions for amputation of, 1240
transverse fissure of cerebrum, 721, 743
Greater anterior gastric artery, 590
cornua of hyoid, 73
centres of ossification for, 103
sac of peritoneum, 990
HAM

Greater sciatic notch, 149
sigmoid cavity of ulna, 131
trochanter, 156
tuberosity of humerus, 124
wing of sphenoid, 33
Grey commissure of cerebrum, 745
matter of cord, 777
of encephalon, 718
in interior of cerebellum, 756
in medulla, arrangement of, 764
of Sylvian aqueduct, 750
tubercle of Rolando, 761
Groin, superficial fascia of, 1165
Groove, antero-lateral, of spinal cord, 776
auriculo-ventricular, 965
bicipital, 124, 1182
cavernous, 33
costo-vertebral, 117
digastric, 40, 84
ethmoidal, 54
infra-orbital, 61
interventricular, 965
lachrymal, 85
lateral, of crus cerebri, 752
for middle meningeal artery, 93
musculo-spiral, 128
mylo-hyoid, 69
naso-palatine, 58
obturator, 149
occipital, 40, 84
oculo-motor, of crus cerebri, 752
optic, 32, 92
peroneal, of cuboid bone, 176
postero-lateral, of spinal cord, 776
pterygo-palatine, 35
sesamoid, of first metacarpal, 143
of first metatarsal, 181
subcostal, 107

for superior longitudinal sinus, 28, 92
uncinate, of uncinate gyrus, 732
Ground bundles of spinal cord, anterior and
lateral, 781
Groups of motor cells in spinal cord, 778
Gubernacular canals, 79
Gubernaculum [=a rudder] testis, the, 1063
development of, 1094
Gudden's commissure, 791
Gums, the, 980

Gustatory [gusto = I taste] artery, 525
Gyri [yúpos a ring], annectant, 728
operti, 729
=
Gyrus, angular, 726
fornicatus, or gyrus cinguli, 731
rectus (=straight convolution), 725
uncinate, 723

HÆMORRHOIDAL [alua blood; péw = I flow]-
arteries, inferior (external), 609
middle, 605
superior, 597
(rectal) of middle sacral, 598
nerve, inferior, 858
plexus, venous, 678
nerve, middle, 873
veins, 678
Half-vertebra (occasional), 13
Hamular [hamus = a hook] process, 35, 79
surgical anatomy of, 1122
1274
INDEX
HAM
HYP

Hamulus [dim. of hamus = a hook], 35, 79
of cochlea, 45, 918
of lachrymal bone, 58
Hand, the, nerve-supply to integument of
dorsum of, 842
skeleton of, 137
surgical anatomy of, 1198
of back of hand, 1210
of fascia and sheaths of, 1204
skin folds or creases of, 1199
synovial membranes of tendons of,
1207
of joints of, 1209
thenar and hypothenar eminences of,
1199
Handle of malleus, 73
Hard palate, the, 980
Head and face, sinuses, of 1113; surgical
anatomy of, 1111
and neck, lymphatics of, 688
veins of, deep, 655
superficial, 648
of astragalus, 172
of caudate nucleus, 740
of femur, 156
of fibula, 168
of humerus, 124
of malleus, 73
of metacarpal bone, 143; first, 143
of metatarsal bone, 179; first, 181
of os magnum, 142
of pancreas, 1023
of radius, 135
of ribs, 106
of stapes, 75
of tibia, 163
of ulna (lower end), 134
Head-kidney, or pronephros, 1092
Heart, the, 963
cavities of, 966
foetal, peculiarities of, 977
lymphatics of, 697
openings and their valves, 969
topography of, 972, 1140
position of, 963
relation to chest wall, 1140
size and weight, 964
veins of, 646
vessels and nerves, 672
Height of average skull, 93
Helicis major et minor muscles, 909
Helicotrema [Exiga spiral; тpμa = a hole],
the, 918
Helix [λ= a spiral], the, 907
Hemiazygos vein, 644
accessory, 644
Hemispheral branches of cerebellar arteries,
542, 543
of anterior cerebral artery, 534
of middle cerebral, 535
of posterior cerebral, 544
Henle, looped tube of, 1048
accessory lachrymal glands of, 903
Hepatic [TаTIKós of the liver] artery, 590
variations, 591
of epigastric, superior, 550
of gastric, 590
of right phrenic, 587
canals, 1020
duct, 1021
涯
​Hepatic lymphatic glands, 704
vessels, 703
plexus (nerve), 870
veins, 672, 1019
1=
Hernia [pvos a branch]-
parts concerned in femoral, 1165
inguinal, 1159
umbilical, 1169
See also Femoral, Inguinal, and Umbilical
Hey, ligament of, 1166
Hey's amputation, incisions for, 1240
Hiatus [a cleft] Fallopii, 39, 92
sacralis, 16
Hilton, laryngeal muscle of, 949
Hilum of corpus dentatum, 756
of kidney, 1043
of ovary, 1090
Hind-kidney, 1093
Hip (innominate) bone, the, 148
development and blood-supply of, 154
joint, arterial and nerve supply and move-
ments of, 264
ligaments of, 259
muscles in relation to, 264
Hippocampal fissure, 731
Hippocampus [iTтóкаμπоs = а sea-horse] major
(= cornu Ammonis), 737
minor (= calcar avis), 736
Horizontal fissure, great, of cerebellum, 754
ramus of pubes, 152
section of brain, definition of, 710
of skull, 89
Horner's muscle, 904
Huguier, canal of (iter chordæ anterius), 40,
83, 105
Humeral artery of acromio-thoracic, 555
Humerus [= the shoulder], the, 124
ossification of, 130
topography of, 1186
Humour, of eye, aqueous, 886
vitreous, 886
Hunter's canal, 1214
Hyaloid [aλos = glass; eldos like] canal,
886
Hydatid of Morgagni, 1065, 1087
=
Hymen [buhy a membrane], the, 1079, 1081
Hyo-epiglottidean ligament, 942
Hyo-epiglottideus muscle, 488
Hyo-glossus [from attachment to hyoid and
tongue yλwooa] muscle, 481; nerve to,
822
=
Hyoid [u, the Greek letter; eidos = like] artery,
of lingual [= supra-hyoid], 514
of superior thyroid [= infra-hyoid], 513
bar, 97
bone, 72
at birth, 103
origin, 97
ossification, 73
Hypogastric [úró under; ya rhp = the stomach]
artery, 604, 1163
branch of ilio-hypogastric nerve, 848
plexus (nerve), 871
Hypoglossal [úró under; yλwooa= the tongue]
=
1=
or twelfth cranial nerve, 820
communicating branch to, from vagus, 818
from superior cervical ganglion, 867
membrane, 925
Hypophysis [uró under; púois, from púw = I
grow] cerebri (= pituitary body), 749
INDEX
1275
HYP
Hypothenar [úró- under ; 0évap = the palm]-
eminence, 363; surgical anatomy of, 1199
fascia of hand, 352
ILEO-CECAL fossa, 1007
valve, 1007
Ileo-colic artery, 594
Ileum [eiλéw = I twist], the, 1003
=
Iliac [ilia the flanks] artery of ilio-lumbar,
602
of obturator, 606
common, 598; collateral circulation,
600; topography of, 1149; varia-
tions, 599
external, 611; collateral circulation
and variations, 612
internal, 600; variations, 600
bone, 149
branch of ilio-hypogastric nerve, 848
of last dorsal nerve, 846
crest, 149
fascia, 368
portion of fascia lata of thigh, 1169
fossa, 149
lymphatic glands, internal and external, 701
notches, 149
spines, 149
tuberosity, 148
veins, common, 672; tributaries, 672;
variations, 673
external, 686; tributary, 687
internal, 677; tributaries, 677
Iliacus muscle, 368; nerve to, 852
minor, or ilio-capsularis muscle, 488
Ilio-costalis (sacro-lumbalis) muscle, 441
Ilio-femoral band, 259
Ilio-hypogastric nerve, 848
Ilio-inguinal nerve, 849
Ilio-lumbar artery, 601
ligament, 209
vein, 672, 677
Ilio-pubal ridge, 149, 153, 155
Ilio-tibial band, 364
Ilio-trochanteric band, 261
Ilium [ilia = the flanks], the, 148
development and blood-supply of, 154
Impressio colica, 1015
duodenalis, 1015
gastrica, 1014
petrosa, 732
renalis, 1015
suprarenalis, 1015
Incisive artery of mandibular, 525
fossa of maxilla (superior maxilla), 60
of mandible (inferior maxilla), 68
nerve of mandibular, 804
Incisor teeth, 94
Incisura [= a notch] intertragica, 908
marsupialis, 753
temporalis, 732
Incus [ an anvil], 74; origin of, 98
Infantile bladder, the, 1058
Infraclavicular lymphatic glands, 695
Infracostal artery, lateral, 550
Infracostales (subcostales)
[infra- below;
costa a rib] muscles, 422
Infra-hyoid artery, 513
Inframandibular (= inframaxillary) nerve, 811
INT

Inframarginal (= superior temporal) convolu-
tion of cerebrum, 729
Infra-orbital artery, 526
canal, 61, 105
foramen, 60, 105
groove, 61
nerve, 808, 900
plexus (nerve), 800, 808
Infrarimal [rimaa chink] portion of larynx,
948, 950
Infrascapular artery of dorsal scapular, 556
Infra-spinatus muscle, 317
Infraspinous artery of posterior scapular, 547
of suprascapular, 546
fossa, 121
Infratrochlear nerve, 797
=
Infundibula [infundibulum a funnel] of
kidney, 1051
Infundibuliform or internal spermatic fascia,
432, 1061
Infundibulum [= a funnel], or conus arteriosus,
87, 968
of brain, 749
of cochlea, 918
of ethmoid, 55,
1
Inguinal [inguen = the groin] canal, 1144, 1160
hernia, causes of, 1618
coverings of, 1162
parts concerned in, 1159
lymphatic glands, deep, 707
superficial, 705
Inion [iviov = the occiput], the, 76, 767, 1111
Inlet of pelvis, 155
thoracic, 117
Innominate artery, 503; topography of, 1141;
variations, 504
bone (see Hip bone), 148
veins, right and left, 640; variations, 642
topography of, 1141
Interarticular fibro-cartilage of acromio-clavi-
cular joint, 230
of knee joint (semilunar), 271
of sterno-clavicular joint, 229
of temporo-mandibular (maxillary
joint, 190
ligament of chondro-sternal joints, 224
of costo-central joints, 219
Intercavernous sinuses of cranium, 659
Interchondral articulations, 225
Interclavicular ligament, 228
muscle, 488
notch, 113
Interclinoid ligament, 35
Intercoccygeal articulations, 216
Intercolumnar or external spermatic fascia,
430, 1061, 1159
fibres of external abdominal ring, 430
Intercondyloid notch of femur, 160
Intercostal [inter-between; costa = a rib]
arteries-
anterior, of internal mammary, 549
of musculo-phrenic, 550
aortic, 581
collateral, of aortic, 582
superior, 550
first, of superior, 551
lymphatics, 696
lymphatic glands, 696
muscles, external, 418
internal, 419
1276
INDEX
INT
Intercostal muscles, action of, 419
nerves, lower, 845; upper, 843
space, structures in, 1137
veins, left lower superior, 641, 645
left upper superior, 645
right superior, lower and upper, 645
Intercuneiform joints, 286
Interior of skull, 88
Interlobar fissures of cerebrum, 722
Intermetacarpal articulations, 225
Intermetatarsal articulations, 292
Intermuscular septa of the sole, 400
of upper arm, 322
Interossei [inter between; os = a bone] muscles
of foot, dorsal, 408
plantar, 408
of hand, dorsal, 357
palmar, 356
Interosseous artery, anterior and posterior, 566
surgical anatomy of, 1197
common, 565
dorsal, of foot, 636
of hand, 574
palmar, 579
recurrent, 566
Da cartilage of sacro-iliac synchondrosis, 212
of symphysis pubis, 218
fibro-cartilages of carpal joints, 249
ligaments of calcaneo-astragaloid joint,
anterior and posterior, 282
of calcaneo-cuboid joint, 288
of carpo-metacarpal joints, 253
of carpus, 250
of cubo-cuneiform joints, 286
of cubo-metatarsal joint, 292
of cubo-scaphoid union, 285
of intercuneiform joints, 286
of intermetacarpal joints, 255
of intermetatarsal joints, 292
of middle tarso-metatarsal joint,
291
of outer tarso-metatarsal (= cubo-
metatarsal) joint, 292
of inferior tibio-fibular joint (=-in-
ferior interosseous ligament), 279
of superior tibio-fibular joint (=su-
perior interosseous ligament), 277
membrane, radio-ulnar, 243
tibio-fibular, 278
nerve, anterior, 838
posterior 841
ridge of fibula, 168
Interosseus primus volaris muscle, 489
Interparietal segment of squamo-occipital
bone, 26
Interphalangeal joints, 258, 294
Intersigmoid fossa, 1011
Interspace, perinæal, deep, 1105
superficial, 1104
Interspinales muscles, 449
Interspinous ligaments, 207
Intertransversales muscles, 449
Intertransverse ligaments of coccyx, 215
of spine, 207
Intertrochanteric line, anterior, 156
posterior, 157
Interventricular artery, anterior, 503, 973
groove, 965
vein, anterior, 646
posterior, 502, 972
JOI
Interventricular vein, posterior, 647, 974
Intervertebral substance of sacro-coccygeal
joint, 214
of spine, 201; origin from
notochord, 295
Intestinal arteries of superior mesenteric, 594
canal, rotation of, 1032
lymphatic glands, 702
trunk, 703
lymphatics (= lacteals), 703
Intestine, large, 1005
cæcum, 1006
ileo-cæcal valve, 1007
vermiform appendix, 1007
colon, 1008
rectum and anus, 1011
blood-supply and structure of,
1012
small, 1000
blood-supply of, 1004
duodenum, 1000
jejunum and ileum, 1003
lymphatics of, 1005
nerves of, 1005
structure of, 1003
Intestines, topography of, 1147
Intrahemispheric nerve fibres, 786
Intraparietal fissure of cerebrum, 726
Intraspinal veins, 668
Intrinsic muscles of larynx, 945
of tongue, 925
Iris [pts the rainbow], the, 883
lymphatic spaces in, 890
zones of, 877
Ischial [oxiov = the hip] ramus, 150
tuberosity, 149
Ischiatic spine, 149
Ischio-cavernosus (= erector penis) muscle,
1072, 1079
Ischio-femoral band, 260
Ischio-rectal (or anal) fascia, 1102
fossæ, 1102; surgical anatomy of, 1153
region, 1097
segment of obturator fascia, 1099
Ischium [ioxiov = the hip], the, 149
development of, 154

Island of Reil, 729
Isthmic border of thyroid cartilage, 939
Isthmus [a neck] of Fallopian tube, 1089
of fauces, 980
of gyrus fornicatus, 731
of middle fossa of base of skull, 92
of thyroid, 953
of uterus, 1081
Iter [a route] e tertio ad quartum ventri-
culum, 749
chordæ anterius (Huguier), 105, 912
posterius, 44, 105, 912
JACOBSON, nerve of (= tympanic, of glosso-
pharyngeal), 814, 928
Jacobsonian cartilages of nose, 717, 928
Jaw, lower, see Mandible

upper, see Maxilla
Jejunum [jejunus = empty], 1003
Joints, movements of, 188
structures entering into formation of, 186
varieties of, 187
See Articulation, for individual joints
INDEX
1277
JUG
Jugular [jugulum the throat] foramen, 83, 93,
104
fossa, 39, 83
ganglion of glosso-pharyngeal, 814
process of ex-occipital, 29
surface of temporal bone, 40
veins, anterior 655,
external, 654; variations, 654; topo-
graphy of, 1130
internal, 665
posterior, 654
Jugulo-cephalic vein, 683
Jugum [= a yoke] sphenoidale, 37
KERATO-THYROID muscle, 489
Key and Retzius, foramina of, 758
Kidney, the, 1042
excretory duct of, 1051
head-, or pronephros, 1092
hind-, or metanephros, 1093
investment and fixation of, 1043
lymphatics of, 704
mid-, or mesonephros, 1093
nerves of, 1049
physical characters of, 1042
position and relations of, 1043
structure of, 1047
topography of, 1148
varieties of, 1050
vessels of, 1048
Knee joint, arterial and nerve supply of, 273
ligaments of, 267
movements of, 275
surgical anatomy of, 1220
synovial membrane of, extent, &c., 1223
LABIA [plural of labiuma lip] of cervix
uteri, 1084
majora, 1076
minora, 1077
Labial artery, inferior, 517
nerves of maxillary, 799
vein, inferior and superior, 651
Labyrinth [Aaßúpiv0os a maze], or internal
ear, 916
membranous, 918
Osseous, 916
=
(lateral mass) of ethmoid, 54
Lacerated [lacerum = ragged] foramen, middle,
or sphenotic, 92
Lachrymal [lachryma = a tear] artery, 530
of middle meningeal, 524
of nasal, 533
bones, 58
canal, 906
canaliculi, 905
caruncle, 875
duct, 61, 84
fossa, 51, 84
gland, 904
accessory (Henle), 903
nerve, 796, 901
papilla, 875
passages, method of probing, 1121
process of inferior turbinal, 57
puncta, 875, 905
position of, 1120.
sac, 905; surgical anatomy of 1120
LAT
Lachrymal sulcus, 58, 85
tubercle, 62
vein, 664


Lachrymo-ethmoidal cells, 55
Lacteals [lac-milk], the (= intestinal lymph-
atics), 703
Lactiferous [lac = milk; fero = I bear] or galac-
tophorous ducts, 1109
Lacuna [lacus a lake] magna of urethra, 1075
Lacunæ of urethra, 1075
Lambda [A, the Greek letter], the, 75, 767, 1111
Lambdoid [from its resemblance to the Greek
letter A; eldos = like] suture, 50
Lamina [= a layer] cinerea, 749
cornea of lateral ventric e, 741
cribrosa of eye, 878, 881, 898
elastic, posterior, 882
quadrigemina, 749
spiralis, 917, 918
terminalis, 709
Laminæ of cervical vertebræ, 7, 10
of lumbar vertebræ, 13
of sacrum, 16
of typical vertebræ, 6
Laminated tubercle (or nodule) of cerebellum,
755
Large cavernous nerve, 873
intestine, 1005
lymphatics of, 703

Laryngeal arteries of inferior thyroid, inferior,
546
of superior thyroid, superior and in-
ferior, 513
lymphatics, deep, 6921
nerves, inferior or recurrent, 818
superior, 818
pouch, 948
veins, 665

Larynx [Aápuy- the larynx], the, 938
cartilages of, 938
interior of, 947
joints of, 944
ligaments of, 943
lymphatics of, 692, 950
mucous membrane of, 947
nerves and blood-vessels of, 950
supra- and infra-rimal portions of, 948
ventricle of, 948
Lateral area of medulla oblongata, 761
cartilages of nose, 927
column of medulla oblongata, 761
cutaneous arteries of aortic intercostal, 583
nerves of abdomen, 845

of thorax, 845
depressions of middle fossa of skull, 92
groove of crus cerebri, 752
ground bundle of spinal cord, 781
horn of spinal cord, 778
ligaments of ankle joint, 280.
of elbow joint, 239
of interphalangeal joints of fingers, 258
of knee joint, 267
of liver, 1019
of toes, 294
of metacarpo-phalangeal joints, 256
of metatarso-phalangeal joints, 293
occipito-atlantal, 194
occipito-odontoid, 198
of temporo-mandibular (maxillary)
articulation, 190
1278
INDEX
LAT
Lateral ligaments of uterus, 1085
vertebral (short), 205
of wrist joint, 247
mass of atlas, 8
of ethmoid, 54
mixed zone of spinal cord, 781
nasal artery, 518
cartilages, 927; origin of, 103
pyramidal tract of cord, 780
root of auditory nerve, 812
sacral arteries, superior and inferior, 602
veins, 677
of middle sacral, 598
sinuses of cranium, 659
spinal arteries of vertebral, 542
ventricles, 735
Latissimus [= broadest] dorsi (= of the back)
muscle, 307
Leg, the, surgical anatomy of, 1228
veins of, 685
vessels of, topography, 1231
Lens [= a lentil], crystalline, the, 880, 885
capsule of, 880
equator of, 885
poles, 885
Lenticular [lens, lentis a lentil] ganglion, 797,
901
=
Lesser anterior gastric artery, 590
cornua of hyoid, 73
occipital nerve, 829
omentum, 993
pancreas, 1023
posterior gastric artery, 590
sac of peritoneum, 990, 992
sigmoid cavity of ulna, 132
splanchnic nerve, 868
superficial petrosal nerve, 808
trochanter, 157
tuberosity of humerus, 124
centre of ossification for, 130
wing of sphenoid, 33
Levator [levare- to lift up] anguli oris muscle,
464
anguli scapulæ muscle, 305
ani muscle, 1099; nerve to, 853
claviculæ muscle, 489
glanduice thyroideae muscle, 489
labii superioris muscle, 466
alæque nasi muscle, 466, 929
menti [mentum = the chin], or levator labii
inferioris muscle, 468
palati muscle, 981
palpebræ superioris muscle, 892
Levatores costarum muscles, 421
Lieutaud, uvula of, 1058
Ligament, or Ligaments [ligare = to bind]-
alar, of the knee, 273
annular, of ankle; anterior, 390; external,
391; internal, 391
of wrist, anterior 328, surgical
anatomy of 1204; posterior
328, surgical anatomy of 1206
astragalo-scaphoid, 287
of astragalus, 172
atlanto-axoidean,
anterior, 196; pos-
terior, 196; transverse, 197
of auricle, anterior and posterior, 908
of bladder, false and true, 1056
broad, of liver, 1019
of uterus, 1085
LIG
Ligament, or Ligaments-
calcaneo-astragaloid, antero-internal, 283;
external, 282; internal, 283; inter-
osseous, 282; posterior, 283
calcaneo-cuboid, inferior (long and short)
and internal, 288
calcaneo-scaphoid, external, 283
of calcaneum, 175
inferior, 287
capsular, see Capsular ligament
carotico-clinoid, of sphenoid, 36
carpal dorsal, 249, 250
palmar, 249, 250

carpo-metacarpal, dorsal and palmar, 253,
254

cervico-basilar, 198
check, of eyeball, external and internal, 896
of spine, 198
chondro-sternal, anterior, 222
posterior, inferior, and superior, 223
chondro-xiphoid, 224
of clavicle, 119
common, of vertebræ, anterior, 203
posterior, 204
conoid, 231
coraco-acromial, 232
coraco-clavicular, 231
coraco-humeral, 235
coracoid, 233
coronary, of knee, 272
of liver, 1019
costo-central (or stellate), anterior, 219
costo-clavicular, or rhomboid, 228
costo-coracoid, 308; origin of, 124
costo-transverse, middle, 221; posterior,

221; superior, 222
cotyloid, 262
crico-thyroid, 944

crucial, of central atlanto-axoidean joint,
197
of knee joint, 270
cubo-cuneiform, dorsal, interosseous, and
plantar, 280
cubo-metatarsal, dorsal, 292; plantar, 291;
interosseous, 292
cubo-scaphoid, dorsal, interosseous, and
plantar, 285
of cuboid, 176
deltoid, of ankle, 280
dorsal, of carpus, 249, 250
falciform, of fascia lata of thigh, 365, 1166
femoral, 1166
of femur, 161
of fibula, 169
gastro-phrenic, 994
of Gimbernat, 430, 1166
glenoid, of interphalangeal joints of foot,294
of hand, 258
of metacarpo-phalangeal joints, 256
of shoulder joint, 235
gleno-humeral, 235
of Hey, 1166
of hip bone, 153
of humerus, 129
hyo-epiglottidean, 942
ilio-femoral, 259
ilio-lumbar, 209
ilio-trochanteric, 261
of incus, 42, 913, 914
infrapubic, 217

INDEX
1279
LIG
Ligament, or Ligaments--
interarticular, of costo-central articulation,
219
of chondro-sternal articulation, 224
interclavicular, 228
interclinoid, of sphenoid, 36
intercuneiform, dorsal, interosseous, and
plantar, 286
intermetacarpal, dorsal and palmar, 255
intermetatarsal, dorsal, interosseous, and
plantar, 292
interosseous, of calcaneo-astragaloid joint,
anterior, 283
posterior, 282
of calcaneo-cuboid joint, 288
of carpo-metacarpal joint, 253
of carpus, 250
of costo-transverse articulation, 221
of cubo-cuneiform joints, 286
of cubo-metatarsal joints, 292
of cubo-scaphoid union, 285
of intercuneiform joints, 286
of intermetacarpal joints, 255
of intermetatarsal joints, 292
of sacro-iliac joint, 212
of tarso-metatarsal joint, middle, 291
outer, 292
of tibio-fibular joints, inferior, 279
superior, 277
interphalangeal, of fingers, 258
of toes, 294
interspinous, 207
intertransverse, of coccyx, 215
of spine, 207
intervertebral, 201
of larynx, extrinsic and intrinsic, 943
lateral, of ankle, 280
of elbow, 239
of interphalangeal joints of foot, 294
of knee joint, 267
of liver, 1019
of hand, 258
of metacarpo-phalangeal joints, 256
of metatarso-phalangeal joints, 293
of temporo-mandibular (maxillary) ar-
ticulation, 190
of uterus, 1085
of vertebræ (= short vertebral), 205
of wrist or radio-carpal joint, 247
of liver, 1019
medio-carpal, anterior and posterior, 250
metacarpal, 255
metacarpo-phalangeal, 256
metatarsal, 292
metatarso-phalangeal, 293
oblique, of middle radio-ulnar articulation,
243
obturator, of stapes, 915
occipito-atlantal, anterior, 193; oblique,
194; lateral, 194; posterior, 193
occipito-cervical, 198
occipito-odontoid, see odontoid
odontoid, central or suspensory, 200
check or lateral, 198
orbicular, of radius, 242
orbito-tarsal, 894
of os calcis, 175
of the ovaries, 1088
palmar, of carpus, 249, 250
palpebral, 904
LIG

petro-sphenoidal, 41
phreno-colic, 994
plantar, long and short, 288
posterior, of ankle, 280
of carpus, 249, 250
of elbow, 239
of knee, 268
of wrist, 246
of Poupart, 430, 1142, 1166
surgical anatomy of, 1211
proper, of the scapula, 232
pterygo-spinous, of sphenoid, 36
pubic, anterior, 217; inferior, 217; pos-
terior, 216; superior, 216
pubo-prostatic, 1056
radio-carpal, anterior and posterior, 246
radio-ulnar, anterior and posterior, 244
of radius, 137
rhomboid, or costo-clavicular, 228
round, of liver, 1019
of uterus, 1086, 1088
sacro-coccygeal, anterior, 214; posterior, 215
sacro-iliac, 211
sacro-lumbar, 209
sacro-sciatic, great, or posterior, 212
small, 213
scapho-cuneiform, 285
of scaphoid (tarsal) bone, 177
of scapula, 123, 232
of sphenoid, 36
spheno-mandibular (maxillary), 190
spino-glenoid, 233
stellate, or anterior costo-central, 219
sterno-clavicular, anter. and posterior, 227
sterno-pericardial, 962
of sternum, 113
stylo-hyoid, 41
stylo-mandibular (maxillary), 190
supracornual, of coccyx, 215
suprascapular, or transverse, 233
supraspinous, of coccyx, 215
of vertebræ, 206
suspensory, central odontoid, 200; origin
of, 295
of eyeball, 895
of lens, 880, 886
of malleus, 74, 914
of penis, 1070
of thyroid gland, 954
tarsal, external, 456
internal [= tendo oculi], 455
tarso-metatarsal, 291
thyro-arytenoid, inferior and superior, 944
thyro-epiglottidean, 942
thyro-hyoid, 943
of tibia, 166
tibio-fibular, anterior and posterior, 277
anterior and posterior inferior, 279
transverse, of central atlanto-axoidean
joint, 197
dorsal, of medio-carpal joint, 250
of heads of metacarpals, 255
of metatarsals, 293
of hip, 262
humeral, 237
of knee joint, 272
of larynx, or crico-arytenoid, 944
of scapula, 233; inferior, 233
superficial, of palmar fascia, 351
of plantar fascia, 1101
1280
INDEX
LIG
Ligament, or Ligaments-
transverse, of inferior tibio-fibular articu-
lation, 279
trapezoid, 231
triangular, of urethra, inferior (= anterior
of ulna, 134
layer of), 1105
superior or deep (= pos-
terior layer), 1106
of uterus, muscular, 1087
peritoneal, 1085
of Winslow, 268
Ligamenta brevia of hand, 352
longa of fingers, 352
subflava of spine, 205; functions of, 208
vaginalia of fingers, 352
Ligamentous artery of ovarian, 596
Ligamentum arcuatum externum, 423, 434
denticulatum, 774
internum, 423
infundibulo-pelvicum, 1086
latum pulmonis, 958
mucosum, 272
nuchæ, 206, 304, 436, 1250
patellæ, 389; surgical anatomy of, 1222
pectinatum iridis, 882
teres [round], 261; origin of, 295
Winslowii, 268
Ligulæ of fourth ventricle, 758
Limbus [a border], corneal, 881
Limbic lobe of cerebrum, 733
Limen [a threshold] insulæ, 729
Line, condylar, of femur, inner and outer, 157
intertrochanteric, of femur, anterior, 156;
posterior, 157
naso-lambdoidal, 770
nuchal, inferior, 27; middle, 26; superior,
26
oblique, of clavicle, 118
of mandible (inferior maxilla), 68
of radius, 136
spiral, of femur, 156, 157
white, of obturator fascia, 1099
Linea [a line] alba [= white], 425, 1141;
viscera behind, 1145
aspera [=rough], 157
quadrata [=square], 157
semilunaris, 431; surgical anatomy of, 1142
splendens [= shining], 774
Lineæ transversa, 427
Lingual [lingua- the tongue] artery, 513
of mandibular (= inferior dental), 525
bone (see Hyoid), 72
glands of mucous membrane, 923
lymphatic glands, 692
nerve [gustatory], 804; methods of di-
viding, 1122
of facial, 809
of glosso-pharyngeal, 815
vein, 665
Lingualis muscle, superior and inferior, 925
Lingula [dim. of lingua a tongue] of cerebellum,
754
=
of sphenoid, 33; at birth, 101
Lips, the upper and lower, 979
of bicipital groove, 124
of iliac crest, 149
Lisfranc's amputation, incisions for, 1240
tubercle on first rib, 108
Lissauer, boundary zone of, 782
LUM
Lithotomy, lateral, parts cut during operation
of, 1151
Liver, the, 1012
blood-vessels, 1019
general position, 1016
ligaments, 1019
lymphatics of, deep, 704
superficial, 703
relations, 1018
structure, 1020
topography of, 1145
varieties, 1023
weight of, 1012
Lobes of cerebellum, biventral, 754
flocculus, 755
posterior, 754
quadrate, 754
slender, 754

tonsillar, 755
of cerebrum, 723
central (= island of Reil), 729
falciform, 723, 732
frontal, 724
limbic, 733
occipital, 726
olfactory, 724
parietal, 725

temporal (= temporo-sphenoidal), 728
of liver, caudate, 1015
quadrate, 1014
Spigelian, 1015
of lung, 960
of thyroid, 953
Lobule of cerebellum, quadrate and posterior,
754
of cerebrum, cuneate (=cuneus), 732
paracentral, 731
quadrate (præcuneus), 732
superior parietal, 726


of ear, 907
of testis, 1064
Lobulus centralis of cerebellum, 754
gracilis of cerebellum, 754
lingualis, 732
Locus [a spot] cæruleus [=blue] of fourth
ventricle, 758
Long buccal nerve, 803
ciliary nerves, 797
(or middle) subscapular nerves, 835
(or terminal) branches of brachial plexus,
835
(or internal) saphenous nerve, 852
pudendal nerve, 857
root (sensory) of lenticular ganglion, 797
thoracic artery, 555
Longissimus [= longest] dorsi [of the back]
muscle, 443
Longitudinal bundle of mesencephalon-
posterior, 781, 783
superior, 753
fissure, great, of cerebrum, 721
of liver, 1014, 1016
sinuses of cranium, inferior (= inferior
sagittal), 958
superior (= superior sagittal), 657
spinal veins, anterior and posterior, 668
Longus colli muscle, 486; nerves to, 832, 835
Looped tube of Henle, 1048

Lower, tubercle of, 968
Lumbar arteries, 587; variations, 588

INDEX
1281
LUM
Lumbar arteries of ilio-lumbar, 602
colotomy, landmarks for, 1148
enlargement of cord, 776
fascia, 433, 1176
lymphatic glands, 701
trunk, 701
nerves, anterior primary divisions of, 846
posterior primary divisions of, 827
plexus, 846; branches, 847
portion of gangliated cord, 869
ribs, 111
veins, 671
ascending, 671
vertebræ, 13, 15
ossification of, 23
Lumbricales [lumbricus = an earthworm]
muscles of foot, 404
of hand, 354
Lung, the, 958
lymphatics of, 697
relations to chest-wall, 1138
root of, structures forming, 960
relation of structures in, 961
structure of, 961
vessels, nerves, and lymphatics of, 962
weight, 961
Lunulæ [dim. of luna- the moon], the, 969
Lymphatic [lympha = water] duct, right, 688,692
glands of abdomen and pelvis, parietal, 700
visceral, 702
aortic, or median lumbar, 701
auricular, posterior, 689
axillary, 695
bronchial, 697
buccal, 690
cardiac, 697
cervical, upper and lower, 692
superficial chain, 691
coeliac, 701
epigastric, 696
epitrochlear, 693
of extremity, lower, deep, 707
superficial, 705
upper, deep, 695
superficial, 693
facial, deep, 692
femoral, deep, 707
superficial, 705
gastric, inferior, 703
superior, 702
gastro-epiploic, 703
of head and neck, deep, 692
superficial, 689
hepatic, 704
iliac, internal and external, 701
infraclavicular, 695
inguinal, deep, 707
oblique and vertical, 705
intercostal, anterior and posterior, 696
lingual, 692
lumbar, median and lateral, 701
mammary, internal, 696
maxillary, internal, 692
mediastinal, 697
mesenteric, 703
meso-colic, 703
2001 occipital, 689
parotid, 689
pectoral, 695
popliteal, 707; surgical anatomy, 1228
LYM
Lymphatic glands, post-pharyngeal, 692
psoas, or transverse lumbar, 701
pulmonary, 697
sacral, 701
saphenous, or superficial femoral, 705
splenic, 704
sternal, or anterior intercostal, 696
or anterior mediastinal, 697
sterno-mastoid, 689
of stomach, 702, 999
subclavian, 695
submaxillary, 690
suboccipital, 689
subscapular, 695
suprahyoid, 690
of thorax, parietal, 696
visceral, 697
tracheal, 697
system (or spaces) of eyeball, 889
of orbit, 901
Lymphatics, the, 688
of abdomen and pelvis, parietal, deep, 700
superficial, 699
visceral, 702
of bladder, 702
of brain, 691, 717
broncho-mediastinal trunk, 697, 698
diaphragmatic, 696
of extremity, lower, deep, 707
of eyeball, 889
of eyelids, 904
of face, 689
upper, deep, 693
superficial, 705
superficial, 693
of Fallopian tubes, 702, 1092
gluteal, 700, 705
of head and neck, deep, 691
of heart, 697
intercostal, 696
superficial, 689
intestinal trunk, 703
of intestine, large, 703, 1012
small, 703, 1005
of kidneys, 704, 1049
of larynx, 692, 950
of liver, deep, 704, 1020
superficial, 703, 1019
of lung, 697, 962
of mammary gland, 696
meningeal, 691
of mouth and tongue, 691
of neck, 689
of nose, 634, 691, 934
of oesophagus, 692, 697
of orbit, 691
of ovaries, 702
of pancreas, 704, 1025
of pelvis, 700
of penis, 700
of pericardium, 697
of perinæum, 700
of pharynx, 692
of prostate, 1060
pudic, 1106
of rectum, 702
of scalp, 689
of scrotum, 700
of spinal cord, 717
of spleen, 704, 1028
4 N
1282
INDEX
LYM
MEC

Lymphatics of stomach, 702, 999
of suprarenals, 705, 1051
of temporal fossa, 691
of testicle, 702, 1061, 1068
of thorax, parietal, deep, 696
superficial, 695
visceral, 697
of thymus, 697
of thyroid, 692
of tongue, 691
of trachea, 692
of ureters, 705, 1053
of uterus, 702, 1092
of vagina, 702
of vas deferens, 1068
of zygomatic fossa, 691
Lymphoid tissue of tongue, 925
Lyre, the, of fornix, 742
MACULA [a spot] lutea [=yellow], 880
Magnum [=great], foramen, 29
Os, 142
Majendie, foramen of, 716, 758
Malar [mala = the cheek]-
bone, 66
ossification of, 68; at birth, 103
canals, 66, 105
centre of ossification of maxilla, 64
nerve of temporo-facial, 810
of temporo-malar, 799
process of maxilla, 62
Male breast, 1109
pelvis, 156
reproductive organs, 1058
Malleolar arteries of anterior tibial, 634
of posterior tibial, 628
fossa of fibula, 168
Malleolus [dim. of malleus = a hammer] of
fibula, external, 168; development of,
169; surgical anatomy of, 1233
of tibia, internal, 163, 166
Malleus [a hammer], the, 73; origin of, 98
Malo-maxillary suture, 84
Malpighi, pyramids of, 1047
Mamma [= the breast], the female, 1108
development and abnormalities, 1110
lymphatics of, 696, 1110
surgical anatomy of, 1136
variations according to age, &c., 1109
vessels and nerves, 1110
male, 1109
lymphatics of, 696, 1110
Mammary artery, external, 555
internal, 548
glandular arteries of aortic intercostals, 583
lymphatic glands, internal, 696
veins, internal, 640
Mammilla [= nipple], 1109; abnormalities, 1110
Mammillary processes of vertebræ, 14
Mandible (or inferior maxilla), 68
ossification, 70
at birth, 102
Mandibular [mando - I chew] artery, or inferior
dental, 525
bar, 97
canal, 69
division of fifth nerve, 801
foramen, 69
gland (submaxillary), 984
Mandibular nerve, or inferior dental, 804
spine, 69
vein, 653
Manubrium [= a handle] of malleus, 73
of sternum, 113; structures behind, 1137
Marginal arteries, right and left, 973
convolution of cerebrum, 731
sinuses of cranium, 659
veins, right and left, 647, 974
Margino-frontal artery of anterior cerebral,
534
Margo [margin] acutus [= sharp] of heart,
968
obtusus [=blunt], 965
Marshall, oblique vein of, 963
Masseter [uaooάouai - to chew] muscle, 469
Masseteric artery of facial, 517
of internal maxillary, 526
of temporal, 522
fascia, 468
nerve, 802
vein, 651, 653
=
Mastoid [uarrós a nipple; eldos = like] an-
trum, 42, 43, 1114; development of, 48
artery, middle, 513
of occipital, 520
of posterior auricular, 521
of stylo-mastoid, 521
000 cells, 43; emissary veins from, 1114
foramen, 84, 93
nerve of lesser occipital, 829
process, 40, 84; development of, 48
sinuses, the, 1114
vein (emissary), 659, 711
Maxilla [=cheek bone], or superior maxilla, 60
ossification, 63
at birth, 102
For Inferior maxilla, see Mandible
Maxillary antrum, 60
artery, external (= facial), 515
internal, 522
centre of ossification, 64
fissure, 62
inferior (=mandibular) division of fifth
nerve, 801
lymphatic glands, internal, 692
nerves, recurrent, 798
process of inferior turbinal bone, 57
of malar bone, 67
of palate bone, 65
sinus (antrum), 62
(= superior maxillary) division of fifth.
nerve, 797
tuberosity, 60, 79
vein, anterior, 651
internal, 653
Maxillo-premaxillary suture, 62, 79
Meatal [meatus = a passage] artery, 521
nerves, 803
Meatus, auditory, external, 40, 83, 909
internal, 38, 93, 104
urinary, external, 1071, 1075
internal, 1055, 1074
relation to pelvic wall, 1055
Meatuses of nose, 62, 933; orifices in, 87
Meckel's cave, 39
diverticulum [diverto I turn aside], 1003
ganglion [= nasal or spheno-palatine], 800
roots and branches, 800
space, in dura mater, 712
INDEX
1283
MED
Median artery [= comes nervi mediani], 566
furrow of back, 1170
lymphatic glands (= aortic lumbar), 701
nerve, 838
in arm, surgical anatomy of, 1188
in forearm, surgical anatomy of, 1196
plexus, venous, anterior, 679
raphe of tongue, 921
Median [from Arabic al-madjan = vein of
Madjan] vein, deep, 679, 682
superficial, 679
basilic, 680
cephalic, 679
Mediastinal, or thymic arteries, 548
lymphatic glands, 697
veins, 461
Mediastinum [medius = the middle; sto = I
stand] of thorax, anterior, 938
middle, 938
posterior, 938
superior, 937
testis, 1064
Medio-tarsal joints, 287;
movements of,
289
Medulla [=marrow, from medius = middle] of
kidney, 1047
oblongata, the, 709, 760
fissures of, 761
internal structure of, 764
veins of, 663
Medullary laminæ of lenticular nucleus, 740
veins, 668
velum, inferior, 755, 757
superior, 757
Medulli-spinal veins, 668
Meibomian follicles, 875
Membrana [= the skin of an animal] basilaris
of cochlea, 920
Shrapnelli, 911
suprachoroidea, 880, 882
tympani, 910; structure of, 911
Membrane, Bowman's, 882
of Bruch, 882
crico-thyroid, 943
Descemet's, 882
hypoglossal, 925
of Reissner, 920
Schneiderian, 930
thyro-hyoid, 943
of trachea, 951
Membranous canal of cochlea, 920
cranium, 97
labyrinth, the, 918
urethra, 1074, 1106
Meningeal [unvy
a membrane] artery of
ascending pharyngeal, 511, 713
of ethmoidals, 532, 713
middle or great, 524, 713; grooves for,
93
posterior, of occipital, 520
of vertebral, 542, 713
small, 525
lymphatic vessels, 691
nerves of glosso-pharyngeal, 814
of hypoglossal, 821
of vagus, 818
veins, middle, 653
extra-medullary, 668
Meninges [uvys a membrane] of brain, 710
=
of spinal cord, 772
MIT

Meningo-rachidian [pάxis = the spine] veins,
668
=
Meniscus [dim. of unvn the moon] of malleo-
incal joint, 913
Mental [mentum = the chin] artery of facial, 517
of mandibular, 525
foramen, 68
nerve of mandibular, 804
protuberance, 68
Mento-hyoideus muscle, 489
Mento-Meckelian centre of ossification in
mandible, 71
Mesencephalon [eyképaλov = brain], the, 709,
749
Mesenteric [uéros = middle; evтepov an intes-
tine] artery, inferior, 596; varia-
tions, 597
superior, 592; variations, 594
topography of, 1150
lymphatic glands, 703
plexuses (nerve), superior and inferior, 871
veins, inferior, 676
superior, 674; tributaries, 675
Mesentery [evrepov = intestine], the, 1003
evolution of, 1036
Mesethmoid [houós a sieve], 54
origin of, 103
=
Mesial [uéros = middle] root of auditory nerve,
812
Meso-colic lymphatic glands, 703
Meso-colon, the, evolution of, 1035
Meso-gaster [uéoos = middle; yaoThp = stomach],
the, 1036
Meso-palatine suture, 62, 79
Meso-sternum [oréρvov chest], 112
=
Mesonephros [uéoos = middle;
kidney], the, 1093
veppós = the
Mesorchium [uéoos = middle; opxis = a testicle],
1063, 1094
Mesovarium, 1094
Metacarpal artery (first dorsal interosseous),
575
bones, 143
ossification of, 146
union of heads of, 255
Metacarpo-phalangeal joint of thumb, 257
joints of four inner fingers, 256
Metacarpus [kaрπós = wrist], bones of the, 143
Metanephros [METά= beyond;
kidney], 1093
Metasternum [ueTά = beyond;
chest], 113
Metatarsal artery, 636
bones, 179
ossification of, 183
union of heads of, 293
νεφρός = the
σTéρvov = the
no ale
Metatarso-phalangeal joints, 293; movements
of, 294
Metatarsus [uerá- beyond; Tapoós = the instep],
the, 179
=
Metencephalon, the, 709, 760
Methods of determining deep origin of spinal
nerves, 779
Metopic [uéTwTOV = the forehead] suture, 50
Meynert's commissure, 791
Mid-kidney, the, 1093
Milk teeth, 96
Miniature condyles of (finger) phalanges, 146
Mitral (bicuspid) valve, 972
topography of, 972, 1141
4 N 2
1284
INDEX
Moderator band, 969
MOD
Modiolus [= the nave of a wheel], 44, 917, 918
central canal of, 918
Molar [mola = a mill: from their grinding
action] teeth, upper and lower, 95
third (wisdom), 96
Moll, modified sweat glands of, 903
Mons [= a mountain] Veneris, the, 1076
Montgomery, tubercles of, 1109
Monticulus [mons = a mountain] cerebelli, 755
Morgagni, hydatid of, 1065, 1087
Morphological neck of humerus, 130
relation of patellar facet to articular
portions of femoral condyles, 162
Morphology [uopph = form; λóyos = discourse]-
nature of, 1
of pectoral girdle, 124
of scapula, 124
of skull, 97
of spine, 33
of transverse ligaments of heads of meta-
tarsal bones, 294
Motor [moveo = I move] nerves of eyelids, 904
of orbit, 900
nucleus of glosso-pharyngeal, 813
of trigeminal, 795
root of lenticular ganglion, 797
of otic ganglion, 805
Mouth, the, 979
lymphatics of, 691
surgical anatomy of, 1121
vestibule of, 979
Mucous membrane of bladder, 1057
of Fallopian tube, 1090
of larynx, 947
of nose, 930
of oesophagus, 988
of pharynx, 985
Schneiderian, 930
of small intestine, 1004
of soft palate, 982
of stomach, 999
of tongue, 921
of ureter, 1053
of uterus, 1085
of vagina, 1081
surface of vagina, 1081
Müller, orbital muscle of, 894
superior palpebral muscle of, 892, 895, 903
Müllerian duct, 1094
Multifidus [multus = many; findo I cleave]
spinæ muscle, 448
Muscle, or Muscles-
actions of, 299; advantages of oblique
attachment of tendons, 301; division
of muscles into the three orders of
levers, 299; importance of the direc-
tion of the tendon at its point of
insertion, 300; of muscles passing over
more than one joint, 301
attachments, nature of, 297; of tendons,
modes of, 297; of bipenniform [bis =
twice; penna a feather] museles, 297;
of biventral [bis and venter = a belly]
muscles, 298; of multipenniform [mul-
tus = many] muscles, 298; of penniform
[penna a feather] muscles, 297; func-
tions of a central tendon, 298
metamorphosis of, into ligaments, 294
into tendons, 294
=
=
Muscle, or Muscles-
migration of, 294
nerve-supply of, 298
MUS

nomenclature of, reasons for, 296
shape of, varieties in, 296
structure of, 297
abductor hallucis, 401
longus pollicis, or extensor ossis meta-
carpi pollicis, 348
minimi digiti, foot, 402
hand, 363
ossis metatarsi quinti, 487
pollicis, 358
abnormal, 487
accelerator urinæ (bulbo-cavernosus), 1072
accessorius ad ilio-costalem, 441
adductor brevis, 380
hallucis, 406
longus, 379
magnus, 382
ossis metatarsi quinti, 467
pollicis, or add. pollicis transversus,362
obliquus, 361
anconeus, 345
anomalus, 487
antitragicus, 909
aryteno-epiglottideus, 947
arytenoideus, 947
attollens aurem, 458
attrahens aurem, 458
azygos pharyngis, 487
uvulæ, 981
of back, classification of, 439
biceps flexor cubiti, 323; surgical anatomy
of, 1186
femoris, 384
brachialis anticus, 325
surgical anatomy of, 1188
brachio-radialis, or supinator longus, 339
buccinator, 462
bulbo-cavernosus (accelerator urinæ), 1072
cervicalis ascendens, 441
chondro-epitrochlearis, 487
chondro-glossus, 481
ciliary, 881, 882
circumflexus palati (= tensor palati), 35,
981
cleido-hyoid, 487
cleido-occipitalis, 475, 487
coccygeus, 1100
complexus, 446
compressor narium, 459, 929
minor, 930
sacculi laryngis, 949
urethræ, 1106
vaginæ, 1107
venæ dorsalis penis, 1072
constrictor, of pharynx, inferior, 985
middle, 986
superior, 986
coraco-brachialis, 321; surgical anatomy
of, 1184
corrugator supercilii, 457
costo-fascialis, 487
cremaster, 432
internal (Henle), 1063
crico-arytenoideus lateralis et posticus, 945
crico-thyroid, 945
crureus, 388
curvator coccygis, 487
INDEX
1285
Muscle, or Muscles-
MUS
deltoid, 316; surgical anatomy of, 1183
depressor alæ nasi, 460, 930
anguli oris, 465
labii inferioris, 467
thyroidea, 488
diaphragm, 423. See Diaphragm
digastric, 478
dilatator naris, anterior, 460, 929
posterior, 461, 929
dorso-epitrochlearis, 488
of ear, external, extrinsic, 458
intrinsic, 909
middle, 915
epitrochleo-anconeus, 488
erector penis (ischio-cavernosus), 1072
spinæ, 440
extensor annularis, 488
brevis digitorum pedis, 415
manus, 488
pollicis, or extensor primi inter-
nodii pollicis, 349
carpi radialis accessorius, 488
brevior, 341
longior, 341
ulnaris, 345
coccygis, 488
communis digitorum, 342
indicis, 350
longus digitorum (pedis), 412
pollicis, or extensor secundi inter-
nodii pollicis, 349
medii digiti, 488
minimi digiti, 344
ossis metacarpi pollicis, 348
metatarsi hallucis, 488
primi internodii pollicis, or extensor
brevis pollicis, 349
hallucis longus, 488
proprius hallucis, 410
secundi internodii pollicis, or exten-
sor longus pollicis, 349
flexor accessorius digitorum pedis, 404
longus, 488
brevis digitorum pedis, 401
hallucis (= pollicis pedis), 405
minimi digiti (hand), 363
pollicis, 360
carpi radialis, 330
pedis, 407
brevis vel profundus, 488
ulnaris, 331
longus digitorum (pedis), 396
hallucis, 398
pollicis, 337
ossis metacarpi pollicis, 360
perforatus, 401
profundus digitorum, 335
sublimis digitorum, 332
frontalis, 455
gastrocnemius, 391
gemellus inferior, 378
superior, 377
genio-hyo-glossus, 481
genio-hyoid, 480
gluteus maximus, 371; surgical anatomy
of, 1217
medius, 373
minimus, 374
quartus, 488
gracilis, 383
MUS

helicis major et minor, 909
of Hilton, or compressor sacculi laryngis,
949
hyo-epiglottideus, 488
hyo-glossus, 481
iliacus, 368
minor, or ilio-capsularis, 488
ilio-costalis (or sacro-lumbalis), 441
incisivi (musculi), 462
38 infracostales, 422
infra-spinatus, 317
interclavicular, 488
intercostal, external, 417
internal, 419
interossei, of foot, dorsal, 408
palmar, 408
of hand, dorsal, 357
palmar, 356
interosseus primus volaris, 489
interspinales, 449
intertransversales, 449
ischio-cavernosus (erector penis), 1072
kerato-thyroid, 489
of larynx, extrinsic and intrinsic, 945
latissimus dorsi, 307; surgical anatomy of,
1174
levator anguli oris, 464
ani, 1099
scapulæ, 305
claviculæ, 489
glandula thyroidea, 489
labii inferioris, 468
superioris (proprius), 466
menti, 468
palati, 981
alæque nasi, 466
palpebræ superioris, 892
levatores costarum, 421
lingualis, 925
longissimus dorsi, 443
longus colli, 486
lumbricales, of foot, 404
of hand, 354
masseter, 469
mento-hyoideus, 489
of mouth, classification of, 461
of Müller, orbital, 894
superior palpebral, 892, 895
multifidus spinæ, 448
mylo-glossus, 489
mylo-hyoid, 479
oblique, of eye, inferior, 893
superior, 892
obliquus abdominis externus, 428
auris, 909
internus, 431
capitis, inferior, 451
superior, 451
obturator externus, 383
internus, 377
occipitalis, 454
occipito-hyoid, 489
occipito-frontalis, 454
occipito-scapular, 307, 490
omo-hyoid, 476
opponens minimi digiti, 364
pollicis, 360
orbicularis oris, 461
palpebrarum, 455
1286
INDEX
Muscle, or Muscles-
MUS
orbito-palpebral (Sappey), 895
of palate, soft, 980
palato-glossus, 483, 980
palato-pharyngeus, 981
palmaris brevis, 352
longus, 331
pectineus, 370
pectoralis major, 309; surgical anatomy
of, 1184
minor, 313; surgical anatomy of, 1184
peroneo-calcaneus internus, 489
peroneo-tibialis, 489
peroneus brevis, 417
longus, 415
quartus, 489
quinti digiti, 489
tertius, 413
of pharynx, 985
plantaris, 393
platysma myoides, 452
popliteus, 394
minor, 489
prærectalis (Henle), 1107
pronator radii quadratus, 338
teres, 328
psoas magnus, 366
parvus, 368, 489
pterygoid, external, 470
internal, 472
pterygoideus proprius, 489
pterygo-spinous, 489
pyramidalis abdominis, 426
nasi, 459, 929
pyriformis, 375
quadratus femoris, 378
lumborum, 435
menti, 467
quadriceps extensor femoris, 387
recti, of eye, 892
rectus abdominis, 426
capitis anticus major, 485
medius, 490
minor, 450
minor, 485
lateralis, 451
posticus, major, 450
femoris, 387
sternalis, 490
rhombo-atloideus, 490
rhomboideus major, 306
risorius, 465
retrahens aurem, 458
minor, 305
rotator humeri, 489
rotatores spinæ, 449
sacro-lumbalis (=ilio-costalis), 441
salpingo-pharyngeus, 981
sartorius, 369
scalenus anticus, 484
medius, 484
posticus, 484
semi-membranosus, 386
semispinalis colli, 448
dorsi, 446
semi-tendinosus, 385
serratus magnus, 313
posticus inferior, 438
superior, 436
soleus, 394
MUS


sphincter ani, external, 1097
internal, 1011, 1097
vesica internus, 1056
spinalis dorsi, 445
splenius capitis, 439
colli, 440
stapedius, 915
sternalis, 490
sterno-cleido-mastoid, 473
surgical anatomy of, 1126
sterno-hyoid, 475
sterno-thyroid, 477
stylo-glossus, 482
stylo-hyoid, 479
stylo-pharyngeus, 987
subanconeus, 326
subclavius, 311
subcostals, 422
subcrureus, 389
subscapularis, 319
supinator radii brevis, 346
longus, 339
supra-clavicularis, 490
supra-spinatus, 317
temporal, 469
tensor palati, 981
tarsi, 457
tympani, 915
vaginæ femoris, 373
teres major, 320
minor, 319
thyro-arytenoideus, 946-
thyro-epiglottideus, 947
thyro-hyoid, 477
tibialis anticus, 410
posticus, 398

tibio-fascialis anticus, 490
trachealis, 952
trachelo-mastoid, 443
tragicus, 909
transversalis abdominis, 433
colli (cervicis), 443
transversus auris, 909
nucha, 304, 490
pedis, 407
perinæi, deep, 1106
superficial, 1072, 1107
trapezius, 302; surgical anatomy of, 1174
triangularis sterni, 421
triceps extensor cubiti, 326; surgical
anatomy of, 1188
suræ, 391
triticeo-glossus, 490
of tympanum, 915
vastus externus, 388
internus, 388
vesico-pubic, 1056
zygomaticus major, 464
minor, 467
Muscular ligaments of uterus, 1087
Musculi incisivi, 462
papillares, 969, 971
pectinati, 968
Musculo-cutaneous nerve of arm, 837

of leg, 859
Musculo-phrenic artery, 550
Musculo-spiral groove, 128
nerve, 841; surgical anatomy of, 1188
Musculus ciliaris Riolani, 902
prærectalis (Henle), 1107
INDEX
1287
MUS
Musculus suspensorius duodeni, 1002
Mylo-glossus muscle, 489
Mylo-hyoid [uúλn = a mill] artery, 525
groove, 69
muscle, 479
nerve, 804
ridge, 68
NARES, posterior, size of, 1124
Narial [nares = the nostrils] orifices, anterior
and posterior, 87
Nasal [nasus the nose] angle of maxilla, 62
artery of ethmoidals, 532
of infra-orbital, 527
lateral, 518
of ophthalmic, 533
of spheno-palatine, 527
transverse, 533
bones, 59
at birth, 103
ossification, 60
cartilages, lateral, origin of, 103
duct, 52, 87, 906
eminence, 50
fossæ, 87; at birth, 100
ganglion (= Meckel's), 800
lymphatics, 691
nerve, 796, 901, 933
inferior, 801
superior, 800
of anterior dental, 799
of maxillary, 799
notch, 51
portion of pharynx, 985
process of maxilla, 62
sinuses, 84, 87
spine, anterior, 51, 87
posterior, 64, 87
veins, 650, 663
transverse, 649
Nasion [nasus = the nose], 88, 767
Naso-lambdoidal line, 770
Naso-palatine artery, 527
groove, 58
nerve [= nerve of Cotunnius], 800
Nates of corpora quadrigemina, 751
Neck, lymphatics of, 689
surgical anatomy of, 1124
triangles of, anterior, 1127
carotid, inferior and superior, 1129
posterior, 1129
submaxillary, 1127
supra-hyoid, 1127
tracheal, or inferior carotid, 1129
veins of, deep, 665
superficial, 654
Nélaton's line, 1210
Nerve fibres, functions and structure of, 710
foramina of skull, primary and secondary,
104
roots, spinal, 779
tracts in thalamencephalon and prosen-
cephalon, 784
Nerve, or Nerves-
abdominal, of vagus, 819
abducent, or sixth cranial, 8051
alveolar, of mandibular, 804
Arnold's, 818
articular, see Articular nerves
NER

auditory, or eighth cranial, 811
auricular, anterior, 803
great, 830
of lesser occipital, 829
posterior, 808
of vagus (= Arnold's), 818
auriculo-temporal, 803
axillary, of brachial plexus, 835
buccal, of facial, 810
long, 803
calcanean, internal, 863
calcaneo-plantar cutaneous, 863
cardiac, of sympathetic, 867
of vagus, cervical and thoracic, 819
cavernous, 873
cervical, primary divisions, anterior, 828

superficial, 831
cervico-facial, of facial, 810
chorda tympani, 808
posterior, 825
ciliary, long and short, 797, 886, 901
circumflex, 835
coccygeal, divisions of, anterior, 854
posterior, 828
cochlear, of auditory, 813
communicantes hypoglossi, 832
of Cotunnius, 800

cranial, 786.
See Cranial nerves
crural, anterior, 851
of genito-crural, 849
cutaneous, of abdomen, 845
calcaneo-plantar, 863
external, 851
of hand, 842
internal, of arm, 836
of leg, 852
lesser, 835
middle, 852
of musculo-spiral, 841
palmar, of median, 838
of ulnar, 840
perforating, of fourth sacral, 853
of popliteal, external, 859
of pudic, 858
internal, 861

of thorax, 845
dental, inferior (= mandibular), 804
superior, 799
descendens hypoglossi, 821
dorsal, of clitoris, 858
of penis, 858, 1106
facial, or seventh cranial, 806
of great auricular, 831
frontal, of ophthalmic, 796, 901
genital, of genito-crural, 849
genito-crural, 849
glosso-pharyngeal, or ninth cranial, 813
gluteal, superior, 854

inferior, 855
hæmorrhoidal, inferior, 858
hypogastric, of ilio-hypogastric, 848
hypoglossal, or twelfth cranial, 820
iliac, of ilio-hypogastric, 848
of last dorsal, 846
ilio-hypogastric, 848
ilio-inguinal, 849
incisive, of mandibular, 804
inframandibular (inframaxillary), 811
infra-orbital, of facial, 810
infratrochlear, of nasal, 797
1288
INDEX
NER
Nerve, or Nerves-
intercostal, upper, 843
lower, 845
intercosto-humeral, 845
interosseous, anterior, 838
posterior, 841
Jacobson's, 814
labial, of maxillary, 799
lachrymal, of ophthalmic, 796
laryngeal, superior and inferior, 808 18
lingual (or gustatory), 804
of facial, 809
of glosso-pharyngeal, 815
lumbar, primary divisions of, anterior, 846
malar, of facial, 810
Co of orbital, 799
NER

pharyngeal, of glosso-pharyngeal, 815
of Meckel's ganglion, 801
of sympathetic, 867
of vagus, 818
phrenic, 832
communicating branch to, 834
plantar, external and internal, 863
digitals, 863
pneumogastric, or tenth cranial, 815
popliteal, external, 859
internal, 861
pterygoid, external, 803
internal, 802
pudendal, long, 857
posterior, 827
pudic, 857
mandibular (= inferior dental), 804
masseteric, of mandibular, 802
mastoid, of great auricular, 830
of lesser occipital, 829
meatal, of auriculo-temporal, 803
of mandibular, 804
median, 838
meningeal, of glosso-pharyngeal, 814
of hypoglossal, 821
recurrent, of mandibular, 801 20
of maxillary, 798
of vagus, 818
mental, 804
musculo-cutaneous, of arm, 837
of leg, 859
musculo-spiral, 841
mylo-hyoid, of mandibular, 804
nasal, 796, 901, 933
inferior, 801
superior, 800
of anterior dental, 799er
of maxillary, 799
naso-palatine, of Meckel's ganglion, 800
obturator, 849
accessory, 850
occipital, great, 827
lesser, 829
smallest, 825 after
oculo-motor, or third cranial, 791
œsophageal, of vagus, 819
olfactory, or first cranial, 788
optic, or second cranial, 790
orbital, of maxillary, 798
of Meckel's ganglion, 800
orbito-temporal, of maxillary, 798.
palatine, anterior (great), 801
external, 801
posterior (small), 801
palmar cutaneous, of median, 838
palpebral, 799
of ulnar, 840
parotid, of auriculo-temporal, 803
patellar, of long saphenous, 853
pectineus, 852
perforating cutaneous, of fourth sacral, 853
perinæal, of fourth sacral, 853
of pudic, 858
superficial, 858
petrosal, deep, great, 800, 865
small, 865
superficial, external, 808
great, 800, 808, 916
lesser, 808
pulmonary, of vagus, 819
radial, 841
recurrent articular, of popliteal, 859
(inferior) laryngeal, 818
meningeal, of mandibular, 801
of maxillary, 798
of vagus, 818
sacral, primary divisions of, anterior, 853
fourth, 853
posterior, 828
saphenous, external or short, 861
long or internal, 852
sciatic, great, 858
small, 856
septal, of Meckel's ganglion, 800
of nasal, 797
of Soemmerring, 857
of soft palate, 982
spheno-palatine, of maxillary, 799
spinal, 822-825
deep origin of, 778
general distribution of, 825
roots of, 779, 822
topography of, 823
spinal accessory, or eleventh cranial, 819
splanchnic, great, 868
lesser, 868
smallest, 868
stapedial, 808
stylo-pharyngeal, 815
subscapular, lower, middle, and upper,
835
supra-acromial, 831
supraclavicular, 831
supramandibular (supramaxillary), 811
supra-orbital, of ophthalmic, 796
suprascapular, 834
suprasternal, 831
supratrochlear, of ophthalmic, 796
sympathetic, 863
gangliated cords of, 864
cranial and cervical portion, 864
lumbar portion, 869
sacral portion, 869
thoracic portion, 868
plexuses of, see Plexuses, nerve
temporal, of facial, 810
of mandibular, 802
of orbital, 798
superficial, 803
temporo-facial, of facial, 810
temporo-malar, 798
thoracic, anterior, external and int., 835
posterior, 834
(or dorsal) spinal, 843

INDEX
1289
Nerve, or Nerves-
NER
thoracic, spinal, primary divs., anterior, 846
first, 843
last, 846
tibial, anterior, 859
tonsillar, 815, 982
posterior, 862
posterior, 827
trigeminal, or fifth cranial, 794
divisions of, mandibular, 801
maxillary, 797
ophthalmic, 795
trochlear, or fourth cranial, 793
tympanic, of glosso-pharyngeal, 814, 916
of sympathetic, 865, 916
ulnar, 840
of uterus, 873, 1092
vagus, or pneumogastric, 815
to vas deferens, 873
vestibular, of auditory, 813
Vidian, 800
of Wrisberg, 835
Nervous coat of eyeball, 884
=
Nervuli [dim. of nervus a nerve] gingivales of
maxillary, 799
of mandibular (inferior dental), 804
Nervus communicans peronei, 859
tibialis, 861
recurrens rami primi (Luschka), 795
Neural arch, 6; morphology of, 25
Neuro-central [veûpov a nerve] suture, 21
Neuro-enteric canal, 749
=
Neuroglia [veûpov = a nerve; yλía-glue], 710
Neurology, definition of, 768
Ninth cranial (= glosso-pharyngeal) nerve, 813
roots, 813
Nipple, 1109; abnormalities of, 1110
Nodule [dim. of nodus a knot] of cerebellum,
755
Nose, the, 926
cartilages of, 927
floor of, 86, 933
meatuses, 933
mucous membrane, 930
OBT
Nucleus, accessory, of trigeminal nerve, 794
sensory, of trigeminal nerve, 794
ambiguus of medulla, 765
amygdaloid, 740
caudatus, 740
of the clava, 766
cuneatus, 766
of descending root of fifth nerve, 750
emboliformis of cerebellum, 756
of facial nerve, 806
fastigii of cerebellum, 756
funiculi teretis, 812
globosus of cerebellum, 756
large-celled (Deiter's) of auditory nerve,
812
(motor, or nucleus ambiguus), of
glosso-pharyngeal, 813
lateralis of medulla, 765
of lens, 886
lenticularis, 740
motor, of trigeminal nerve, 795
olivary, 766
small-celled (chief) of auditory nerve, 811
(sensory, or accessorio - vago-glosso-
pharyngeal) of glosso-pharyngeal,
813
tegmental (red), 752
of third and fourth nerves, 750
Nuhn, gland of, 923
Nutrient artery of clavicle, 546
of femur, 620
of humerus, greater tuberosity, 558
shaft, 563
of ilium, 606
upper end, 562
medullary, of fibula, 627
of tibia, 628
of radius, 566
of ulna, 568
Nymphæ [vúuon = a bride], or labia minora, 1077

muscles of, 929
roof, 86, 931
septum, 86, 928
vessels and nerves, 930, 933
Notch, cotyloid, of acetabulum, 153
ethmoidal, 50
iliac, anterior and posterior, 149
interclavicular, 113
intercondyloid, of femur, 160
nasal, 51
pterygoid, 35
of Rivini, 43, 911
scapular, 121
sciatic, greater and lesser, 149
sigmoid, of mandible, 70
spheno-palatine, 66
supra-orbital, 50
suprascapular, 122
trigeminal, 38
Notochordal [v@Tos = the back; xopon = a cord]
region in the chondral skull, 97
Nuchal [Arabic nugrah hollow at nape of
neck], lines, 26
Nuck, canal of, 1088
Nucleus [= a kernel],-
=
accessory, of auditory nerve, 812
OBELION [oẞeλós = an arrow], the, 75
1=
Obex [a bar], the, 758
Oblique diameter of pelvis, 155
measurement of, 156
fasciculus of pons Varolii, 760
line of clavicle, 118
of fibula, 168
of mandible (inferior maxilla), ex-
ternal and internal, 68
of radius, 136
muscles of orbit, inferior, 893
superior, 892
ridge of scapula, 121
of tibia, 166
of ulna, 134
sinus, 962
vein of heart (Marshall's), 647, 963, 974
Obliquus auris muscle, 909
capitis inferior muscle, 451
superior muscle, 451
externus abdominis muscle, 428
internus muscle, 431
Obturator [obturo
crest, 153
=
I stop up] artery, 606
fascia, 1098
foramen, 148, 153
groove, 149
1290
INDEX
OBT
ORB

Obturator ligament of stapes, 915
muscle, externus, 383
internus, 377; nerve to, 857
nerve, 849
accessory, 850
vein, 677
Occipital [ob = against; caput = head: the part
of the head opposite the forehead]-
artery, 518; topography of, 1117
of posterior auricular, 521
bone, 26; at birth, 100
development of, 30
condyles, 30, 82
convolutions of cerebrum, 728
crest, external, 26
internal, 27, 93
fissures of cerebrum, 727
groove, 40, 84
lobe of cerebrum, 726
lymphatic glands (= suboccipital), 689
nerves, great, 827
small, 829; topography of, 1130
smallest, 825
point, 76, 88
protuberance, external, 26
internal, 27
sinus of cranium, 658
suture, 75
vein, 651
of diploë, 656
Occipitalis muscle, 454
Occipito-atlantal articulation, 193
Occipito-cervical ligament, 198
Occipito-frontalis, aponeurosis, 454, 1115
muscle, 454
Occipito-hyoid muscle, 489
Occipito-mastoid suture, 93
Occipito-scapular muscle, 489
Occipito-temporal convolutions of cerebrum,
superior and inferior, 732
Ocular conjunctiva, 876
muscles, insertions of, 879
actions of, 893
Oculo-motor groove of crus cerebri, 752
nerve (third cranial), 791
divisions of, 792
Odontoid [odous = a tooth; eidos = like] liga-
ment (central occipito-odontoid), 198
process, 9; morphology of, 25
Esophageal [olw, otow I carry; payeiv
eat]
=
arteries of aorta, 581
of gastric (coronary), 590
of inferior thyroid, 546
of left phrenic, 587
of right gastro-epiploic, 591
lymphatics, upper, 692
thoracic, 697
nerves of vagus, 819
plexus (nerve), 819
veins, 645
1
= to
Esophagus [ofw I carry; payev = to eat],
the, 987
relations of, in neck, 987
in thorax, 988
structure, 988
Olecranon [λένη
=
head], the, 131
fossa, 129
process, 131
the elbow; краvíоv
=
the
Olfactory [olfacere = to smell] bulb, 788
lobe of cerebrum, 724
nerve, 788, 933
sulcus [=straight], 725
tract, 788
Olivary eminence of sphenoid, 32, 92
process, 32, 92
Olive, superior, 812
Omental (epiploic) arteries of right gastro-
epiploic, 591
(descending epiploic) of left gastro-
epiploic, 592
Omentum [= the caul enclosing the bowels],
gastro-splenic, 994; evolution of, 1040
great, 993; evolution of, 1037
length of, 993
lesser, or gastro-hepatic, 993; evolution of,
1036
Omo-hyoid [uos = a shoulder] muscle, 476
Opening, saphenous, surgical anatomy of, 1213
Operculum [= a lid], the, 722
Ophryon [oppus = eyebrow], 88
[ὀφρύς
Ophthalmic [opeaλuós = the eye] artery, 530, 899
division (first) of fifth cranial nerve, 795
ganglion (= ciliary or lenticular), 797
veins, common, 663
inferior, 653, 664; tributaries, 665
superior, 663; tributaries, 664
Opisthion [orio@tos = hinder], 79, 82
=
Opisthotic [omo0ev behind; ous, gen. wrós
the ear] centre of ossification, 47
Opponens [= opposing] minimi digiti muscle,
364
pollicis muscle, 360
Optic [oтоμα = I see] chiasma, 749, 790
commissure, 749, 790
peduncles of, 784
disc, 877
foramen, 32, 84, 92, 104
groove, 32, 92
nerve, 790, 897
sheaths of, 897
radiation, 790
thalamus, 746
corona radiata of, 784
tract, 790
Ora [ora an edge] serrata, 880
-
Orbicular bone, 913
ligament, 242
tubercle of incus, 75
Orbicularis oris [orbiculus = a little circle; os,
oris mouth] muscle, 462, 902
palpebrarum [palpebra = eyelid] muscle,
456
Orbiculus ciliaris, 882
Orbit [orbita = a circle], the, 84
arrangement of contents of, 890
arteries of, 899
fascia of, 893
lymphatics of the, 691
muscles of, 891
muscular attachments in, 86
nerves of, 900
veins of the, 663, 900
Orbital artery of anterior cerebral, 534
of infra-orbital, 527
of middle meningeal, 524
of temporal, 522
convolutions of cerebrum, 725
curve, 901
INDEX
1291
ORB
PAL
Orbital fascia, 894
margin of frontal lobe, 724
muscle, 894
nerve, or temporo-malar, 798
from Meckel's ganglion, 800
periosteum, 894
plate, of frontal, 50
process of malar bone, 66
vein, 652
of palate bone, 65
Orbito-frontal artery of middle cerebral, 535
Orbito-palpebral muscle, 895
Orbito-sphenoids, 33
Orbito-tarsal ligament, 894
Organ of Giraldès, 1065, 1093
Orifices of ejaculatory ducts, 1074
=
Os [os, ossis a bone] cordis, 972
calcis, see Calcaneum
magnum, 142
planum of ethmoid, 54
trigonum, 172; development of, 173
Os [os, oris = mouth] uteri, internum et exter-
num, 1084
Osseous spiral lamina, 44
labyrinth, 916
portion of Eustachian tube, 913
portion of external auditory meatus, 910
Ossicles [ossiculum a little bone], epipteric,
53, 78
=
auditory, 73, 74, 75; origin of, 97
Ossification, centres of, in-
astragalus, 172
calcaneum, or os calcis, 175
atlas, 21
axis, 22
carpal bones, 142
clavicle, 119
cuboid, 176
cuneiform bones of tarsus, external, 179
internal, 177
middle, 178
ethmoid, 55
femur, 162
fibula, 169
frontal, 52
hip bone, 154
humerus, 130
hyoid, 103
lachrymal, 58
malar, 68
mandible, or inferior maxilla, 71
maxilla, or superior maxilla, 63
metacarpus, 146
metatarsus, 183
nasal, 60
occipital, 30
palate, 66
parietal, 50
patella, 163
phalanges, of foot, 184
radius, 137
ribs, 111
of hand, 148
scaphoid, of tarsus, 177
scapula, 123
sphenoid, 36
sternum, 114
styloid process, 98
temporal, 47
tibia, 167
Ossification, centres of, in-
turbinals, inferior, 57
sphenoidal, 56
tympano-hyal, 98
ulna, 134
vertebræ, cervical, sixth or seventh, 23
vomer, 59
coccygeal, 24
lumbar, 23
sacral, 23
typical, 21


Osteogenesis [oσTéov = a bone; yéveσis = forma-
tion], 1
Ostium [= an opening] abdominale of Fallo-
pian tube, 1089
Otic [ous the ear] ganglion [= Arnold's], 805
Outlet of pelvis, 155, 1096; dimensions of, 156
Ovarian [ovum = an egg] arteries, 596, 1091
bulb, 671
lymphatics, 702
veins, 671, 1092
Ovaries [ovum = an egg], the, 1090
Oviducts (or Fallopian tubes), the, 1088
Ovisacs, or Graafian follicles, 1090
Ovula [dim. of ovum] Nabothi, 1085
PACCHIONIAN glands, 716; structure of, 718
Pacinian corpuscles, 839
Palate, the, 980
arterial and nerve supply of, 982
mucous membrane of, 982
muscles of, 980
structures cut in paring edges of cleft,
1124
surgical anatomy of, 1124
bone, the, 64
ossification of, 66
at birth, 102
Palatine artery, ascending or inferior, 516
of ascending pharyngeal, 511
descending or posterior, 527
canals, accessory, 65
anterior, 62, 87
external, 65
posterior, 65, 77
foramina, 79
fossa, anterior, 62
nerves, anterior (great), posterior (small),
and external, 801
sutures, 79
vein, inferior or descending, 651
superior, 653
Palato-ethmoidal cells, 55
Palato-glossus muscle, 483, 980
Palato-pharyngeus muscle, 981, 987
Palato-quadrate bone, representative of, in


man, 98
Palmar arch, deep, 576
branches and variations, 576
surgical anatomy of, 1204
superficial, 568
surgical anatomy of, 1203
variations, 569
bursa, great, 334, 1207
cutaneous nerve of median, 838
of ulnar, 841
fascia, 351; surgical anatomy of, 1206
superficial transverse ligaments of, 351
Palmaris brevis muscle, 352
1292
INDEX
PAL
Palmaris longus muscle, 331; nerve to, 838
Palpebral [palpebra = eyelid] aperture, 814
artery, 533
of lachrymal, 531
of supra-orbital, 531
conjunctiva, 875, 903
fascia, 894
folds or grooves, inferior and superior,
875
ligament, inner (or tendo oculi), 874, 904
outer, 904
muscle, inferior, 903
superior, 893, 895, 903
veins, inferior, 651
superior, 650
Pampiniform [pampinus = a tendril] plexus,671
Pancreas [Tav = all; xpéas = flesh], the, 1023
blood-supply of, 1024
duct of, 1024
lesser, 1023.
1=
lymphatics and nerves of, 704, 1025
topography of, 1147
Pancreatic area of anterior surface of kidney,
1046
artery, greater, of splenic, 592
lesser, of hepatic, 590
of splenic, 592
lymphatics, 704
plexus (nerve), 870
Pancreatico-duodenal artery, inferior, 593
plexus (nerve), 871
vein, 675
superior, 591
Papilla [ a teat], lachrymal, 875
optic, 877
Papillæ of kidney, 1047
of tongue, 921
Paracentral lobule, 731
Paradidymis [παρά
ticle], 1065
=
beside; diduuos = the tes-
Parallel fissure of cerebrum, 728
Parenchyma of lung, 962
Parietal [paries = a wall] artery, 535
bone, 48
ossification, 50
at birth, 101
convolution, ascending, 726
eminence, 48
lobe of cerebrum, 725
lobule, superior, 726
lymphatic glands of pelvis, 700
of thorax, superficial and deep, 696
lymphatics of pelvis, 699
of thorax, 695
vein of diploë, external, 656
Parieto-mastoid suture, 78, 93
Parieto-occipital fissure, 722, 731
vein of diploë, 656
Parieto-temporal artery, 535
Parotid [apá near; obs = the ear] artery of
posterior auricular, 521
of temporal, 522
fascia, 468
gland, the, 982
duct of, 984; surgical anatomy of, 1119
vascular and nervous supply, 984
lymphatic glands, superficial, 689
nerves of auriculo-temporal, 803
vein, 651, 653
Parovarium, the, 1086
PEN

Pars basilaris of inferior frontal convolution, 725
bulbosa of urethra, 1075
ciliaris retinæ, 880, 884
frontalis, of central lobe, 729
intermedia of Wrisberg, 806
intermedialis (Köbelt) of vagina, 1079
orbitalis of inferior frontal convolution, 725
parieto-falciformis, of central lobe, 729
temporo-parietalis, of central lobe, 729
triangularis of inferior frontal convolution,
725
Patella [ a small pan], the, 162
1=1
dislocation of, mechanism, 1222
ossification of, 163
relations to femoral condyles, 1222
surgical anatomy of, 1220
Patellar branches of long saphenous nerve, 853
facet on femoral condyle, 160; morpho-
logical relation to articular portions of
the condyles, 162
rete [a net], 624
Pecquet, cistern of (receptaculum chyli), 698
Pectineo-femoral band, 260
1
Pectineus [pecten the pubic bone] muscle, 370
nerve to, 832
Pectoral [pectus = the breast] artery of acro-
mio-thoracic, 555
of anterior circumflex, 557
fascia, 308
girdle, morphology of, 124
lymphatic glands, 695
Pectoralis major muscle, 309; surgical ana-
tomy of, 1184
minor muscle, 313; surgical anatomy of,
1184
Peculiar ribs, 108-110
vertebræ, 8-13, 15
=
Pedicle [pes a foot] of vertebræ, 6, 9, 13, 15
Peduncles, cerebellar, 754, 784
of optic thalamus, 784
of pineal body, 746, 747
Pelvic fasciæ, 1098; surgical anatomy of, 1156
plexus (nerve), 873
portion of ureter, 1052
segment of obturator fascia, 1099.
viscera, lymphatics of, 702
Pelvis [a basin], the, 155
axis of, 156
diameters of, 155
false, 155
fascia of, 1098
inlet of, 155
lymphatic glands of, parietal, 700
lymphatics of, 699
measurements of, 156
outlet of, 155, 1096; dimensions of, 156
position of, 156
sex differences, 156
true, 155
veins of, 676
Pelvis of kidney,superior, inferior, and common,
1051
Penile [penis a tail] angle, the, 1075
=
Penis [= a tail], the, 1069
coverings of, 1069
dorsal artery of, 611, 1104
nerves of, 1106
lymphatics of, 700
structure of, 1070
suspensory ligament of, 1070

INDEX
1293
PER
Perforated space, anterior, 748; posterior, 720
Perforating arteries, anterior, of plantar digi-
tals, 631
lateral, of internal mammary, 549
of middle meningeal, 525
of palmar arch, deep, 579
posterior, of external plantar, 630
of profunda femoris, 620
of submental, 517
cutaneous nerve of fourth sacral, 853
Pericardiac artery of internal mammary, 549
of phrenic arteries, 587
veins, 641
of thoracic aorta, 579
Pericardium [Tepí = around; kapdíα = the heart],
the, 962
lymphatics of, 697
relations of, 963
vessels of, 963
vestigial fold of, 963
Periglottis, the, 942
Perilymph, the, 918
Perinæal arteries, superficial, 609
transverse, 610
body (in female), 1107
fascia, deep, anterior layer, 1105
posterior (superior), 1106
superficial, deep layer of [= Colles'],
1103
interspace, superficial, contents of, 1104
deep, contents of, 1105
lymphatics, superficial, 700
nerves, the, 858
branch of fourth sacral, 853
Perinæum [repí = around; vaiw= I am situated],
female, 1107
male, 1096
proper, 1103
surgical anatomy of, 1150
triangles of, 1151
Periorbita, 894
Periosteal [repí around; doréov a bone] artery
of supra-orbital, 531
Periosteum, orbital, 894
=
Periotic [Tepi around; obs = the ear] capsule,
97
=
cartilages, 97
Peripheral nervous system, the, 786
Perirenal, or capsular arteries, 594
Peritoneal artery of common iliac, 600
of superior epigastric, 550
ligaments of bladder, 1056
of liver, 1019
of uterus, 1085
Peritoneum [Tepi = about; Teivw= I stretch],
arrangement of, explained, 1028
evolution of, 1028
final changes in, 1034
general characters of, 989
greater and lesser sacs of, 990, 992
recto-vaginal pouch of, 992
recto-vesical pouch of, 992
traced in longitudinal section of the body,
992
in transverse section, 990
Peroneal [Tepóvn = the pin of a buckle] artery,
627
anterior, 627
posterior, 628
surgical anatomy of, 1233
PHA
Peroneal groove of calcaneum, 174
of cuboid, 176
nerve [external popliteal], 859
tubercle of calcaneum, 174
Peronei tendons, where divided, 1238
Peroneo-calcaneus internus muscle, 489
Peroneo-tibialis muscle, 489
Peroneus [Tepóvn = the pin of a buckle, or the
fibula] brevis muscle, 417
longus muscle, 415; action upon arches of
foot, 1247
quartus muscle, 489
quinti digiti muscle, 489
tertius [the third] muscle, 413
Perpendicular fissure, internal, 722
occipital fasciculus, 786
plate of ethmoid, 54
Pes [a foot] or crusta of crus cerebri, 752
anserinus [anser = a goose], 810
hippocampi, 737
Petit, triangle of, 1175
Petro-mastoid canal, 43
Petro-occipital suture, 93
Petro-sphenoidal foramen, 38, 93, 104
ligament, 41
notch, 93
process, 38
suture, 92
Petro-squamosal suture, 38
Petro-squamous sinus of cranium, 657, 661
Petrosal [Térpa = a rock] artery, 524, 915
nerve, deep, great, 800, 865
small, 865
superficial, external, 808
great, 800, 808, 916
lesser, 808,
foramen for, 39, 93
portion of temporal bone, 38; at birth,
101
sinuses, superior and inferior, 660
Petrous ganglion of glosso-pharyngeal, 814
Peyer's patches, 1004
=
Phalanges [4áλay a rank of soldiers: from
their regularity] of fingers, 146
ossification of, 148
of toes, 183
ossification of, 184
Pharyngeal [pápuys - the throat] aponeurosis,
985
artery, ascending, 510
of pterygo-palatine, 527
of spheno-palatine, 527
of Vidian, 527
bursa, 987
lymphatics, 692
muscles, 985
nerves of glosso-pharyngeal, 815
of Meckel's ganglion, 801
of superior cervical ganglion, 867
of vagus, 818
recess, 987
tonsil, 987
tubercle, 82
veins, 665
walls, 985
Pharyngo-epiglottidean fold, 942
Pharynx [pápuy- the throat], the, 985
divisions of (buccal and nasal), 985
interior of, 987
muscles of, 985
1294
INDEX
PHR
POS

Phrenic [ophy the mind: the diaphragm was
supposed to be the seat of the mind-
artery, inferior, 586; variations, 587
of inferior thyroid, 546
of musculo-phrenic, 550
of superior epigastric, 550
superior, 548
nerve, the, 832
communicating branch from brachial
plexus to, 834
veins, inferior, 672
Phreno-colic ligament, 994
Pia [= tender] mater [= mother], cerebral, 717
spinal, 774
Pillars of the external abdominal ring, 430, 1159
of the fauces, 980
of the fornix, anterior and posterior, 742
Pineal [pinus = a fir-cone] body, 747
Pinna [a feather], the, 907
Pisiform bone [pisuma pea], 140
articulations with carpus, 249
Pituitary [pituita = the nasal secretion] body
(= gland), 749
membrane (Schneiderian), 830
Plantar [planta = the sole] arch, 629
arteries, external, 628
internal, 631
surgical anatomy of, 1242
digital, 630, 637
fascia, 399; functions of, 1246
nerves, external and internal, 863
digitals, 863
Plantaris [planta = the sole] muscle, 393
Plate of lateral nasal cartilages, inner and outer,
927
fronto-nasal, 97
pterygoid, internal and external, 35;
origin of, 98
Platysma myoides [Tλárvoμa = a plate; μûs =
a muscle; eldos-like] muscle, 452
Pleura [λeupá- the side], the, 958
relation to chest-wall, 1139
costalis, 958
lymphatics of, 697
pulmonalis, 958
Pleural arteries, 582
Plexus, nerve, cranial or spinal-
brachial, 832
cervical, 829
coccygeal, 854
gulæ, 819
infra-orbital, 800, 810
lumbar, 846
patellæ, 852
pulmonary, posterior, 819
sacral, 854
subsartorial, 852
subtrapezial, 831
sympathetic--
aortic, 871
cardiac, superficial and deep, 869, 975
carotid, 865
cavernous, 865
cœliac, 870
coronary (gastric), 871
(cardiac) left and right, 870, 977
cystic, 871
diaphragmatic, 871
gastro-epiploic, right and left, 870
hæmorrhoidal, middle, 873
Plexus, nerve, sympathetic-
hepatic, 870
hypogastric, 871
mesenteric, superior and inferior, 871
pancreatic, 870
pancreatico-duodenal, 871
pelvic, 873
prevertebral, great, 869
prostatic, 873
pyloric, 871
renal, 871
solar, 870
spermatic, 871
splenic, 870
suprarenal, 871
uterine, 873
vaginal, 873
vesical, 873
venous-
anterior median, of forearm, 679
choroid, of lateral ventricles, 738
of fourth ventricle, 757
of third ventricle, 744
dorsal, of hand, 679
hæmorrhoidal, 678
pampiniform, 671
prostatico-vesical, 677
pterygoid, 653
of Santorini (female urethra), 1079
spinal, anterior and posterior, 667
vesical, 678
Plica [a fold] semilunaris, 431, 875
ureterica, 1057
Plicæ ciliares, 880
Pneumogastric [πνεύμων = the lung; γαστήρ
= the stomach] nerve (= vagus, or
tenth cranial), 815
twig to, from facial, 808
origin, 815
Poles, of eyeball, 878
of lens, 885
Pomum [=an apple] Adami, 939
Pons [a bridge] hepatis [ap the liver], 1014
Varolii, 709, 758
fibres of, 670
veins of, 663
1=
Pontal [pons, pontis = a bridge] arteries, 543
Popliteal [poples the ham] artery, the, 621
surgical anatomy of, 1227, 1231
variations, 623
bursæ, 1226
lymph glands, 707; surgical anatomy, 1228
nerves, external, 859
internal, 861
space, surgical anatomy of, 1225
vein, 686; surgical anatomy of, 1227
variations, 686
Popliteus [poples = the ham] muscle, 394
minor muscle, 489
Portal [porta a gate] vein, 673; sinus of, 673
tributaries, 674
canals, 1020
fissure, or transverse, of liver, 1016
Portio [= a part] major et minor of trigeminal
nerve, 794
Post-central sulcus of cerebrum, 726
Postero-lateral arteries of posterior cerebral, 544
Postero-median arteries of anterior cerebral, 544
Post-glenoid tubercle, 38
Post-olivary sulcus of medulla oblongata, 761
INDEX
1295
POS
Post-pharyngeal lymphatic gland, 692
Post-sphenoid centres of ossification, 36
at birth, 100
Pouch of Douglas, 992, 1080, 1083
laryngeal, 948
of Rathke, 987
recto-vaginal, 992, 1080, 1083
recto-vesical, 992
Poupart's ligament, 430, 1142, 1166, 1211
Præcentral sulcus of cerebrum, 724
Præcuneus or quadrate lobule of cerebrum, 723
Præputium clitoridis, 1077
Prærectalis muscle of Henle, 1107
Pre-coracoid cartilage, 124
Pre-maxillary centre of ossification, 64
Pre-molar teeth (bicuspids), 95
Pre-palatine centre of ossification, 64
Pre-patellar bursa, surgical anatomy of, 1223
Prepuce, the, 1069
Pre-sphenoid bone, 33; at birth, 100
centres of ossification, 36
Pre-sternum, 113
Pressure curves in cancellous bones, 4
Preventricular artery, 502, 983
veins, 648, 974
Prevertebral artery of ascending pharyngeal, 511
fascia, 473, 1133
plexuses, great, 869
Princeps cervicis artery, 520
hallucis artery, 637
pollicis artery, 577
Process, acromion, 122
angular, external and internal, 50
auricular (ear-shaped) of sacrum, 18
of inferior turbinal bone, 57
clinoid, anterior, middle and posterior, 32,92
coracoid, 122
coronoid, of ulna, 131
of mandible, 70; topography of, 1122
costal, of atlas, 9
of axis, 9
of cervical vertebræ, 8
of seventh cervical, 9
of sacrum, 16
ethmoidal, of inferior turbinal bone, 57
falciform, of Burns, 1166
frontal, of malar bone, 67
hamular, 35, 79; topography of, 1122
of incus, long, and short, 75
lachrymal, of inferior turbinal bone, 57
malar, of maxilla, 62
of malleus, Folian, short and slender, 74
mammillary [dim. of mamma = breast], 14
morphology of, 25
mastoid, 40, 84
maxillary, of inferior turbinal bone, 57
of malar bone, 67
of palate bone, 65
nasal, of maxilla, 62
odontoid, 9
olecranon, 131
olivary, 32, 92
orbital, of malar bone, 66
of palate bone, 65
petro-sphenoidal, 38
sphenoidal, of palate bone, 65
styloid, 40, 73, 84; at birth, 98
of base of third metacarpal, 145
of fibula, 168
of radius, 137
PTE
Process, styloid, of ulna, 133
supracondyloid, 128
of thyroid gland, middle or pyramidal,
954
turbinal, of lachrymal bone, 58
tympano-hyal, at birth, 98
unciform, of ethmoid, 54
of unciform bone, 142
vaginal, of temporal bone, 40, 84
vermiform, of cerebellum, superior and
inferior, 753
zygomatic, of malar bone, 67
Processes, articular, of vertebræ, 6, 7, 8, 9, 13,
15, 16, 18


morphology of, 25
ciliary, 880
spinous, of vertebræ, 6, 7, 9,10, 13, 14, 15, 16-
bifid, 10
transverse, of vertebræ, 6, 7, 8, 9, 12, 13,
14, 15, 16, 18
morphology of, 25
Processus cochleariformis, 43
gracilis of malleus, 74
reticularis of cord, 778
vaginalis of peritoneum, 1063
Profunda [profundus deep] artery of femoral,

618
=
of brachial, inferior and superior,
562
variations, 562
vein, 686
Promontory of sacrum, 15
of tympanum, 42, 912
Pronator [pronus = face downwards] quadratus
[=square] muscle, 338
radii teres muscle, 328; nerve to, 838
Pronephros [pó = before; reopós = the kidney],
1092
Pro-otic [pó before; obs = the ear], centre of
ossification, 47
Prosencephalon, 709; nerve tracts in, 784
Prostate [pó before; lornu-I stand], the,
1058
structure and functions, 1060
vessels and nerves of, 1060
Prostatic fissure, 1059
plexus, nerve, 873
venous, 677
sinuses, 1060, 1074
urethra, 1074
Prostatico-vesical venous plexus, 677
Protuberance, occipital, external, 26


internal, 27
Psoas [óa-the loin] lymph glands, 701
(magnus) muscle, 366; nerve to, 847
parvus muscle, 368, 489
Pterion [Trépu= a wing], the, 53, 78, 1111
Pterotic centre of ossification, 47
Pterygoid [Trépuέ a wing] artery, 526
fossa, 35, 65, 79
lobe of parotid gland, 988
muscle, external, 470; nerve to, 803
notch, 35
internal, 472; nerve to, 802
plates, 35; origin of, 98
plexus (venous), 653
ridge, 34, 77
veins, 653
Pterygoideus proprius muscle, 489
Pterygo-maxillary fissure, 77
1296
INDEX
PTE
REC

Pterygo-palatine artery, 527
canal, 35, 65, 77, 105
groove, 35
Pterygo-pharyngeal artery, 527
Pterygo-spinous ligament, 36
Pterygo-spinous muscle, 489
Pubes [pubescens = covered with hair], the, 151
Pubic arch, 155
artery, of deep epigastric, 613
of obturator, 606
ligaments, 216, 217
portion of fascia lata of thigh, 1169
spine, 152
Pubo-prostatic ligaments, 1056
Pudendal [pudeo = I am ashamed] nerve,
long, 857
Pudic [pudeo I am ashamed] artery, accessory,
=
605
external, superficial and deep, 618
internal, 608, 1106; topography of, 1219
lymphatics, 1106
nerve, 857
vein, 677, 1106
Pulmonary [pulmo=lung] artery, 491, 962
orifice of, 969
topography of, 972
in fœtus, 491
after birth, 492
lymph glands, 697
nerves, anterior, 819
plexus, posterior, 819
sinuses (of Valsalva), 497, 969
valves, 969; topography of, 972, 1140
veins, the, 639
Pulvinar a cushion], 746
Puncta cruenta (vel vasculosa), 729
lachrymalia, 905
Punctum [= a point] lachrymale, 875
Pupillary zone of iris, 877
Putamen [a shell or husk], 740
Pyloric artery, inferior, 591
superior, 590
orifice of stomach, 996
plexus (nerve), 871
vein, 674
=
Pylorus [Tuλwpós a gatekeeper], the, 996.
Pyramid of cerebellum, 755
of tympanum, posterior, 42, 913
Pyramidal body of medulla, 761
process of thyroid, 954
tracts of cord, anterior and lateral, 780
Pyramidalis abdominis muscle, 426
nasi muscle, 459, 929
Pyramids of Ferrein, 1048
of Malpighi, 1047
=
Pyriformis [pirus a pear] muscle, 375
QUADRATE artery of anterior cerebral, 534
cartilage of nose, accessory, 928
lobe of cerebellum, 754
of liver, 1014
lobule of cerebrum (= præcuneus), 732
Quadratus [= square] femoris muscle, 378
lumborum muscle, 435; nerve to, 847, 855
menti [quadratus = square; mentum
chin] (= depressor labii inferioris), 467
Quadriceps extensor femoris muscle, 387
nerve to, 852
=
RADIAL artery, in forearm, 571
surgical anatomy of, 1197
variations, 572
in the palm (deep palmar arch), 576
variations, 576
at the wrist, 574
carpal, anterior and posterior, 574
recurrent, 573
condyle (external) of humerus, 129
nerve, 841; surgical anatomy of, 1197
vein, superficial, 679
Radialis indicis artery, 577
Radio-carpal joint, ligaments of, 246
movements of, 248
Radio-ulnar joints, inferior, 243
middle, 242
superior, 242
Radius [=a spoke], the, 135
ossification of, 137
movements of, on ulna, 244
Rami [plural of ramus] communicantes of
gangliated cord, lumbar, 869
thoracic, 843, 868
of middle and inferior cervical ganglia, 867
of superior cervical ganglion, 865
of sympathetic system, white and grey,
864
Ramus [= a branch] of ischium, 150
of mandible, 69
occipitalis of cerebrum, 726, 727
parietalis of occipital artery, 713
of pubes, descending, 151
horizontal, 152
subcutaneus malæ, 799
Ranine [rana a frog] artery, 515
=
Raphe [paph a seam] of corpus callosum, 734
median, of tongue, 921
Rathke, pouch of, 987
Receptaculum [=a vessel] chyli [xôλos = juice],
698
Recess of ischio-rectal fossæ, anterior and
posterior, 1102
pharyngeal, 987
tonsillar, 980
Recessus infundibuli, 749
Rectal (hæmorrhoidal) artery of lateral sacral,
602
middle (= middle hæmorrhoidal), 604
of middle sacral, 598
triangle, 1151
Recti [rectus = straight] muscles of orbit, 892
Recto-uterine ligaments, 1087
Recto-vaginal pouch of peritoneum, 992, 1083
Recto-vesical fascia, 1056, 1101
pouch of peritoneum, 992
Rectum [rectus = straight], the, 1009, 1011
lymphatics of, 702
surgical anatomy of, 1155
Rectus abdominis muscle, 426; sheath of, 435
capitis anticus major muscle, 485
nerve to, 832
medius muscle, 490
minor muscle, 485
nerve to, 932
lateralis muscle, 451
nerve to, 832
posticus major muscle, 450
minor muscle, 450
femoris muscle, 387
sternalis muscle, 490

INDEX
1297
REC
Recurrent arteries of deep palmar arch, 579
interosseous, 566
radial, 573
tibial, anterior and posterior, 634
ulnar, anterior and posterior, 565
nerves, articular, of external popliteal, 859
laryngeal, 818
meningeal, of mandibular, 801
of maxillary, 798
of vagus, 818
Recussus [recutio = a recoiling] pinealis, 747
Red (tegmental) nucleus, 752
Reissner, membrane of, 920
Renal [ren the kidney] arteries, 594
=
variations, 594
topography of, 1150
of lumbar, 588
duct, 1051
lymphatics, 704
plexus (nerve), 871
veins, 670
Reproductive organs in the female, 1076
in the male, 1058
Respiration, organs of, 958
Restiform [restis = a cord] body of pons, 762, 783
Rete [a net], carpal, anter. and posterior, 566
testis, 1064
Retina [rete a net], 880, 884
Retinacula [retinere to hold back] of capsule
of hip, 259
Retinal arteries, 887
pigment layer, 880
Retrahens [retraho I draw back] aurem
muscle, 458
Revehent nerve (grey ramus communicans), 864
Rhinencephalon, 724
Rhombo-atloideus muscle, 490
Rhomboid [sóußos = a rhomb] depression, 119
ligament, 228; origin from subclavius, 295
Rhomboideus major muscle, 306
minor muscle, 305
Rhomboids, nerve to, 834
Ribs, the, 106
bicipital, 111
development
of, 110
lumbar, 111
cervical, 111; variations in, 112
SAG
Rivinian segment of tympanum, 911
Rolando, fissure of, 722; development of, 723
tubercle of, 761
Roof bones of skull, 26
Roots of auditory nerve, 811
of glosso-pharyngeal nerve, 813
of lenticular ganglion, 797
of lung, structures forming, 960
of Meckel's ganglion, 800
of olfactory nerve, 788
of optic nerve, 790
of otic ganglion, 805
of penis, 1069
of spinal nerves, 779, 822
of tooth, 94
of trigeminal nerve, 794
Rostrum [a beak] of corpus callosum, 733
of sphenoid, 32
Rotation of intestinal canal, 1032
Rotator humeri muscle, 489
Rotatores spinæ muscles, 449
Round ligament of liver, 1019
of uterus, 1086, 1088
Rugæ [= wrinkles] of vagina, 1081
1
SAC, lachrymal, 906
pleural, 958
of peritoneum, greater, 990
lesser, 990, 992
37
Saccule [dim. of saccusa bag], the, 919
Sacral [sacer sacred] aorta, see Sacral arteries,
middle
arteries, lateral, superior and inferior, 602
of middle sacral, 598
middle, 598; variations, 598
cornua, 16
foramina, 16-
groove, 17
lymph glands, 701
nerves, fourth, 853
plexus, 854
posterior, 828
peculiar, 108
variations in number and shape, 111
Ridge, basal, of teeth, 94
external condylar, 126
gluteal, of femur, 157
of hip bone, 148
ilio-pubal, 149, 153, 155
interosseous, of fibula, 168
oblique, of infraspinous fossa, 121
of ulna, 134
of tibia, 166
supracondyloid, 127
of trapezium, 141
Rima [a chink] glottidis, 949
pudendi, 1076
Ring, abdominal, external, 1142, 1159; effect
of position on, 1159
internal, 1144, 1161
femoral, 1167; position of vessels round,
1168
Rings, cartilaginous, of trachea, 951
Risorius [rideo= I laugh] muscle, 465
Rivini, notch of, 43, 911
primary divisions of, anterior, 853
portion of gangliated cord, 869
promontory, 15
veins, lateral, 677
middle, 672
vertebræ, 25
Sacro-coccygeal articulation, 214
ligaments of, 214; morphology of, 295
Sacro-iliac articulation, or synchondrosis [σúv
= together; xóvopos = cartilage], 211
Sacro-lumbalis (ilio-costalis) muscle, 441
Sacro-lumbar ligament, 209
Sacro-vertebral angle, 209
differences in male and female, 210
measurements of, 211
Sacrum [sacer = sacred: the bone was offered
as a sacrifice by the ancients], the,
15
morphology of, 25
ossification of, 23
sexual differences in, 18.
Sagittal [sagitta = an arrow: from its straight
1
direction] axis of eyeball, 878
layer of transversus perinæi muscle, 1106
section of brain, definition of, 710
of skull, 88
40
1298
INDEX
SAG
Sagittal sinuses (= longitudinal) of cranium,
inferior, 658; superior, 657
suture, 50
alivary glands, the, 982
Santorini, cartilages of, 942
fissures of, 908
plexus of (female urethra), 1079
Saphenous [from Arabic al-safin = hidden; less
probably from oapnvns = manifest] ar-
tery, 621
lymph glands (= superficial femoral), 705
nerve, long or internal, 852
short or external, 861; varieties,
861
opening, 365, 1166, 1213, 1228
veins, long (internal), 683
short (external), 685
topography of, 1228, 1231
Sappey, orbito-palpebral muscle of, 895
Sartorius [sartor- a tailor] muscle, 369; nerve
to, 852
Scala [a staircase] tympani, 45, 918
vestibuli, 45, 918
Scaleni, nerve to, 831, 835
Scalenus [σkaλnvós of unequal sides] anticus
muscle, 484
=
medius muscle, 484
posticus muscle, 484
Scalp, lymphatics of, superficial, 689
surgical anatomy of, 1115
topography of vessels of, 1116
Scalp and face, superficial veins of, 648;
anterior, 648; lateral, 652; posterior,
651
Scapho-cuneiform articulation, 285
=
Scaphoid [σkápna boat; eldos = like: from
its shape] carpal bone, 138
fossa, 35, 79
of helix of auricle, 908
tarsal bone, 176; ossification, 177
Scapula [probably from σkаπávna spade], the,
120
=
arterial anastomoses of, 1175
morphology of, 124
muscles of, surgical anatomy of, 1175
ossification of, 123
Scapular ligaments, 232
notch, 121
Scarpa's foramina, 62, 79, 105
triangle, surgical anatomy of, 1213
Schneiderian membrane, 930
Sciatic [ioxiov=the hip] artery, 607; topo-
graphy of, 1219
nerve, great, 858; topography of, 1219
small, 856
notch, greater, 149
lesser, 149
veins, 677
Scleral sulcus, 877
Sclerotic [okλnpós = hard], the, 881
Scrotum [a skin], integument of, 1060
lymphatics of, 700
septum of, 1060
vessels and nerves of, 1061
Second cervical nerve, anterior primary division
of, 828
posterior primary division of, 827
cranial (=optic) nerve, 790
division (= maxillary) of fifth nerve, 797
rib, 110
SIN

Semicircular canals, external, 43, 44, 917
posterior, 44, 917
superior, 39, 44, 917
Semilunar bone, 139
cartilages of knee, external, 271
internal, 272
fold of conjunctiva, 878
ganglia, 871
valves, aortic, 972; topography of, 972
pulmonary, 969; topography of, 972
Semi-membranosus muscle, 386
Semi-spinalis colli muscle, 448
dorsi muscle, 446
Semi-tendinosus muscle, 385
Sensory nucleus of glosso-pharyngeal nerve, 813
accessory, of trigeminal, 795
Septal artery, ascending, 527
cartilage, 928
nerve of Meckel's ganglion, 800
of nasal, 797
Septum [sepio = I hedge in], auricular, 968
artery of, 527
fibrous, of tongue, 925
lucidum, 743
nasi, 86, 928
pectiniforme, 1070
posticum, of spinal arachnoid, 774
scroti, 1060
ventricular, 968
Serratus [serra a saw] magnus muscle, 313
posticus inferior muscle, 438
superior muscle, 436
Sesamoid [onoauov a small seed, sesame; eloos
= like] bones of great toe, 293
bones of interphalangeal joint of great toe,
294
of thumb, 257
cartilages of nose, 928
grooves on head of first metacarpal, 143
of first metatarsal, 181
plate, plantar, 293
Seventh cranial (= facial) nerve, 806
Sheath, femoral, 1167
of optic nerve in orbit, 897
of parotid, 1119
Shoulder joint, ligaments of, 234
movements of, 237
muscles in relation to, 237
relation of biceps tendon to, 238
cause of roundness of, 1182
surface markings of, 1180
Sigmoid [from its likeness to the Greek letter
sigma] artery, 597
cavity of radius, 137
of ulna, greater, 131
lesser, 132
flexure of colon, 1009
notch of mandible, 70
sinus, 659
Sinus [= a hollow] alæ parvæ, or spheno-parietal,
661
⚫ of aorta, 497
basilar, 659, 711
cavernous, 660, 711
circular, 659, 711
inferior, of Winslow, 659
coronary, of heart, 966, 974
of galactophorous ducts, 1109
jugularis, 659
of kidney, 1043; structures lying in, 1047

INDEX
1299
SIN
Sinus, lateral, 659, 711
longitudinal, inferior, 658, 711
superior, 657, 711
of Morgagni, 986
oblique, of heart, 962
obliquus, or straight, 658, 711
occipital, 658, 711
pedis, 173
perpendicularis, or straight, 658, 711
petrosal, inferior and superior, 660, 711
petro-squamous, 661
pocularis, 1074
of portal vein, 673
pyriformis of larynx, 947
rectus, or straight, 658, 711
rhomboidalis, 778
sagittal, or longitudinal, inferior, 658, 711
sigmoid, 659
spheno-parietal, 661, 711
straight, 658, 711
superior, 657, 711
tentorii, or straight, 658, 711
transverse, 659, 711
uro-genital, 1095
venosus, or atrium, 966
Sinuses, ethmoidal (cells), 55
frontal, 51
intercavernous, 659
marginal, 659
mastoid (cells), 43, 1114
nasal, 84, 87
prostatic, 1060, 1074
sphenoidal, 32, 87, 1115
of Valsalva, or pulmonary, 497, 969
venous, of cranium, 656
Sixth cranial (abducent) nerve, 805, 900
Skull, anterior aspect of, 84
base of, exterior, 78
regions of, 79
subcranial, 79
suboccipital, 84
zygomatic, 79
at birth, 98
bones of (classification), 26
exterior of, 75
lateral aspect of, 76
posterior aspect of, 75
superior aspect of, 75
interior of, 88
base of (floor), 89
fossæ of, anterior, 89
middle, 92
posterior, 93
section of, coronal, 89
horizontal, 89
sagittal, 88
foetal, general characters of, 98
nerve foramina of, 104
Skull-cap, average thickness of, 1113
measurements of (average), 93
Slender lobe of cerebellum, 754
process of malleus, 74
Small cavernous nerve, 873
deep petrosal nerve, 865
intestines, lymphatics of, 703, 1005
blood-supply, 1004
nerve-supply, 1005
structure of, 1003
occipital nerve, 829; topography of, 1130
(posterior) palatine nerve, 801
SPH
Small sacro-sciatic ligament, 213; origin from
coccygeus, 295
sciatic nerve, 856
Smallest splanchnic nerve, 868
Smegma præputii, 1069
Snuff-box space of hand, 1210
Socia[a companion] parotidis, 983
Soemmerring, nerve of, or long pudendal, 857
Soft palate, 980
parts cut in paring edges of cleft, 1124
Solar [sol = the sun] plexus, 870
Soleus [solea = a sole-fish] muscle, 394
Solitary glands of intestine, 1004
Space, epicerebral, 718
epispinal, 718
intervaginal, of optic nerve, 897
Meckel's, 712
perforated, anterior, 748
posterior, 720
subarachnoid, 716, 717
of optic nerve, 897
subdural, 715, 717
of optic nerve, 897
Tenon's, 897
Spaces, lymphatic, of eyeball, 889
of Fontana, 882
of orbit, 901
Spermatic [orέpua seed] artery, 595; varia-
tions, 596
cord, 1068; constituents of, 1068
fascia, external, middle, and internal,
1061, 1159
plexus (nerve), 871
veins, 671
Spermatozoa [onéрuа = seed; ov=an ani-
mal], 1064
Spheno-ethmoidal cells, 55
Sphenoid [op
a wedge; eidoç = like: from
its wedging in the other bones of
the skull] bone, the, 35
ossification of, 36
at birth, 100
Sphenoidal artery of pterygo-palatine, 527
crest, 32
of spheno palatine, 527
fissure, 33, 84, 92, 105
process of palate, 65
sinuses, 32, 87, 1115
turbinal bones, 56; at birth, 102
Spheno-malar fissure, 85
foramina, 78, 85, 105
suture, 78
Spheno-mandibular (maxillary) ligament, 190
Spheno-maxillary fissure, 77, 85, 105
fossa, 77
ligament, 190
Spheno-palatine artery, 527, 934
foramen, 65, 77, 87, 105
ganglion (= Meckel's), 800
nerves, 799
notch, 66
vein, 653, 934
Spheno-parietal sinus of cranium, 661, 711
suture, 78, 92
Sphenotic [ophv=a wedge; ouç= the ear]
cartilage, 97
foramen, 82, 92
Sphincter [opiyyw I bind] ani externus, 1097
ani internus, 1011, 1097
iridis, 884
402
1300
INDEX
SPH
Sphincter vesicæ internus, 1056
Spigelian lobe of liver, 1015
Spinal accessory nerve, 819; topography of,
1130
arteries, anterior, lateral, and posterior, 542
of aortic intercostals, 582
of deep cervical, 551
of inferior thyroid, 545
of lateral sacrals, 602
column, 18; curves of, 20
ossification, 20
cord, the, 771
arachnoid of, 773
dura mater of, 772
external character of, 774
internal structure of, 776
pia mater of, 774
tracts of, 779
nerves, 822
classification and number, 825
deep origin of, 778
general distribution, 825
primary divisions, anterior, 828-863
roots of, 779, 822
posterior, 825-828
topography of, 823, 1175
plexus, venous, anterior and posterior,
667
portion of spinal accessory, 820
veins, 667
longitudinal, anterior and posterior,
668
Spinalis dorsi muscle, 445
Spine, alar, 35, 83
bones of the, 5
ethmoidal, 32, 92
frontal, anterior, 51, 87
posterior, 64, 87
iliac, anterior and posterior inferior and
superior, 149
mandibular, 69
nasal, 51
of palate bone, 64, 87
pubic, 152
of scapula, 122
of tibia, 163
Spino-glenoid ligament, 233
Spiral canal of modiolus, 45, 917
lamina, osseous, 44
line of femur, 156
Splanchnic [onλáy xvov a viscus] nerve, great,
868
lesser, 868
smallest, 868
Spleen [orλ= the spleen], the, 1025
size and varieties of, 10271
structure, relations, and blood- and nerve-
supply, 1028
topography of, 1148
Splenial [splenium a pad] centre of ossifica-
tion in mandible, 71
Splenic artery, 591; variations, 592
of left phrenic, 587
lymphatics, 704
nerve plexus, 870
vein, 675
Splenium [a pad] of corpus callosum, 733
[σπλήνιον:
Splenius [ohviova bandage: from its bind-
ing down other muscles] capitis muscle,
439
STY

Splenius colli muscle, 440
Spongy portion of urethra, 1075
Spot, yellow, of eye, 878
Squamo-mastoid furrow, 40
Squamo-occipital bone, 26
Squamo-sphenoidal suture, 78, 92
Squamosal portion of temporal bone, 37
at birth, 101
Squamous [squamaa scale] suture, 50, 78, 92
Stapedic [stapes = a stirrup] artery, 521
Stapedius muscle, 915; nerve to, 808
Stapes [a stirrup], 75; origin of, 98
Stars of Verheyen, 1049
Stellate figures of lens, 886
(anterior costo-central) ligament, 219
Stenson's canals, 62
duct, 984
foramina, 79
Stephanion [orépavoc
[στέφανος
a crown], 78
Sternal abnormalities, 116
artery of internal mammary, 549
end of clavicle, 119
of ribs, 106
lymphatic glands, 696
Sternalis muscle, 490
Sternebræ, 112
Sterno-clavicular articulation, 229; structures
behind, 1127
layer of deep cervical fascia, 1132
Sterno-cleido-mastoid [kλeica key = clavi-
cle] muscle, 473; nerve to, 831
surgical anatomy of, 1126
Sterno-hyoid muscle, 475
Sterno-mastoid artery, inferior, of supra-
scapular, 546
of occipital, 520
of superior thyroid, 513
lymphatic glands, 689
Sterno pericardial bands or ligaments, 962
Sterno-thyroid muscle, 477
Sternum [orέpvov = the breast or chest], the,
112
blood-supply and development of, 113
cleft, 116
ossification and abnormalities of, 116
in the young subject, 113
Stomach, the, 996
alterations of position, 998
lymphatics of, 702, 999
nerves and blood-supply of, 999
structure, 998
topography of, 1146
Straight convolutions (gyrus rectus), 725
sinus of cranium, 658
sulcus (= olfactory), 725
Stratum zonale, 785
Stria [a stripe or streak] pinealis, 746, 747
terminalis, 741
Striæ acusticæ, 758
longitudinales, 734
medullares, 758
Stylo-glossus muscle [from attachment to sty-
loid and tongue-y2oooa], 482
Stylo-hyoid muscle, 479; nerve to, 809, 821
Styloid [oruhoça pen; eidos = like] bone of
carpus (occasional), 146
process, 40, 73, 84
at birth, 98
morphology and development of, 98
segments of, 73

INDEX
1301
STY
Styloid process of base of third metacarpal, 145
of fibula, 168
of radius, 137
of ulna, 134
Stylo-mandibular (maxillary) ligament, 190
Stylo-mastoid artery, 521, 915
foramen, 40, 84, 105, 193
Stylo-maxillary (mandibular) ligament, 190
Stylo-pharyngeus muscle, 987; nerve to, 815
Subanconeus muscle, 326
Subaponeurotic connective tissue of scalp, 1115
Subarachnoid space, cerebral, 716, 717
spinal, 774
tissue, cerebral, 716
spinal, 774
Subcapsular epithelium of lens, 886
Subclavian artery, the, 536
first portion, 536
second portion, 538
third portion, 538
variations, 539
of suprascapular, 546
lymphatic glands, 695
vein, 682; variations and tributaries, 683
Subclavius muscle, 311; nerve to, 834
Subcostal angle, 117
artery (last dorsal), 583
groove, 107
vein, 645
Subcranial region of basis cranii, 79
Subcrureus muscle, 389
Subdural space, 715, 717
Sublingual artery, 515
fossa, 68
duct (=Rivini's), 984
ganglion, 805
gland, 984
Submandibular (= submaxillary) ganglion, 805
Submaxillary artery, 517
duct (Wharton's), 984
fossa, 69
ganglion (= submandibular), 805
gland (= submandibular), 984
vascular and nerve supply of, 984
lymph glands, 690
triangle of neck, 1127
vein, 651
Submental artery, 517
vein, 651
Subnasal point, 88
Suboccipital lymphatic glands, 689
region of basis cranii, 84
Subperitoneal artery of common iliac, 600
connective tissue, 994
Subsartorial nerve plexus, 852
Subscapular artery, 555; variations, 557
of posterior scapular, 547
of suprascapular, 546
fossa, 120
lymphatic glands, 695
nerves, lower, middle, and upper, 835
vein, 682
Subscapularis muscle, 319
Substantia ferruginea, 758
gelatinosa centralis, 710, 778
Rolandi, 777
nigra of crura cerebri, 752
reticularis alba, 732
spongiosa, 778
Subthalamic body, 752
SUP
Subtrapezial nerve plexus, 831
Sulcus [a furrow]--
of cerebellum, cerebelli superior, 754
lateralis dorsalis, 761

ventralis, 761
longitudinalis medianus, 758
paramedianus dorsalis, 761
parapyramidalis, 761
post-olivary, 761
of cerebrum, central, 722
centralis insulæ, 729
choroideus, 746
circularis Reilii, 729
fronto-marginalis, 724
occipitalis anterior, 728
olfactory (straight), 725
paracentralis, 731
post-central, 726
præ-central, 724
subparietalis, 725, 731
lachrymal, 58
scleral, 877

of spinal cord, longitudinalis posterior, 776
paramedianus dorsalis, 776
Superciliary [supercilium = eyebrow] ridge,
50, 84
Supinator [supinus = face upwards] longus
muscle (see Brachio-radialis), 339; nerve
to, 841
radii brevis muscle, 346
Supra-acromial nerves, 831
Supraclavicular nerves, 831
Supraclavicularis muscle, 490
Supracondyloid process, 128
ridge, 127
Supracornual ligament of coccyx, 215
Supra-hyoid lymphatic glands, 690

triangle, 1127
Supramandibular (= supramaxillary) nerve, 811
Supramarginal convolution, 726
Supramastoid crest, 37, 40
Supra-occipital segment of squamo-occipital
bone, 26
Supra-orbital artery, 531; topography of, 1116
foramen, 50
nerve, 796
notch, 50
ridges, 50
vein, 650, 653


Suprarenal arteries, inferior, 594, 595, 1051
bodies, 1050
middle, 595, 1051
superior, 587, 1051
accessory, 1050
morphology of, 1093
structure, 1050
vessels and nerves, 1051
lymphatics, 705
nerve plexus, 871
veins, 671, 1051
Suprarimal portion of larynx, 948
Suprascapular artery, 546
foramen, 122
ligament (transverse), 233
nerve, 834
notch, 122
vein, 654
Supra-spinatus muscle, 317
Supraspinous artery of posterior scapular, 547
of suprascapular, 546
1302
INDEX
SUP
Supraspinous fossa, 121
ligaments of coccyx, 215
of vertebræ, 206
Suprasternal artery of suprascapular, 546
nerves, 831
Supratrochlear artery, 514
foramen, 129
fossa, 51
nerve, 796
Sural [sura = the calf of leg] arteries, 624
Surgical neck of humerus, 125
Surgical and topographical anatomy of-
abdomen, the, 1141; regions of, 1247
abdominal ring, external, 430, 1142, 1159
effect of position on, 1159
internal, 436, 1144, 1161
amputations of leg, arteries cut in, 1233
ankle, the, 1233
annular ligaments of ankle, 1237; of
wrist, anterior, 1204; posterior, 1206
anterior tibial artery, 1233
anus, 1155
nerve, 1242
aorta and iliac arteries, 1149
arches of the foot, 1242
arm, the, 1186
axilla, 1184
back, the, 1170
of wrist and hand, 1210
biceps muscle, 1186
bicipital groove, 1182
brachial artery, 1187
brachialis anticus muscle, 1188
burse of foot, 1241
buttocks, the, 1216
coeliac artery, 1150
coraco-brachialis muscle, 1184
crural arch (= Poupart's ligament), 1166
cutaneous nerves of forearm, 1197
deep cervical fascia, 1130
crural arch, 1167
deltoid muscle, 1183
diaphragm, 1144
dorsal artery of foot, 1242
elbow, the, 1188
arterial anastomoses around, 1191
veins in front of, arrangement of,
1191
eyelids and lachrymal apparatus, 1119
fascia lata of thigh, 1166
pubic and iliac portions of, 1169
fascia and sheaths of hand, 1204
female external genitals, 1156
femoral artery, 1214
canal, 1167
ring, 1167
position of vessels around, 1168
sheath, 1167
foot, the, 1238
forearm, the, 1193
fossa on posterior surface of abdominal
parietes, 1163
gall bladder, 1146
gluteal artery, 1219
great sciatic nerve, 1219
head and face, 1111
heart, relation to the chest wall, 1140
hernia, femoral, course of, 1168
coverings of, 1169
parts concerned in, 1165
SUR

Surgical and topographical anatomy of-
hernia, inguinal, coverings of, 1162
causes of, 1168
parts concerned in, 1159
umbilical, coverings of, 1170
parts concerned in, 1169
hypogastric arteries (obliterated), 1163
inguinal canal, 1144, 1160
interosseous arteries of arm, 1197
intestines, large and small, 1147
ischio-rectal fossa, 1153
jugular vein, external, 1130
kidneys, 1148
knee, the, 1220
latissimus dorsi muscle, 1174
leg, the, 1228
linea alba, 1141
semilunaris, 1142
Lisfranc's or Hey's amputation, lines of
incision for, 1240
liver, 1145
lower extremity, 1210
lumbar fascia, 1176
lungs, outlines and relations to chest walls,
1138
mamma, the, 1136
manubrium, parts behind, 1137
median nerve, 1188, 1196
mesenteric arteries, 1150
mouth, the, 1121
musculo-cutaneous nerve on foot, 1242
musculo-spiral nerve, 1188
nares, posterior, 1124
neck, the, 1124
triangles of, anterior, 1127
carotid, inferior and superior, 1129
posterior, 1129
submaxillary (supra-hyoid), 1127
palate, soft, 1124
palmar arch, deep, 1204
superficial, 1203
fascia, 1206
pancreas, 1147
parotid gland, 1119
patella, the, 1220
pectoralis major et minor muscles, 1184
pelvic fascia, 1156
perinæum and genitals, 1150
triangles of, 1151
peroneal artery, 1233
peronei muscles, 1238, 1247
plantar arteries, 1242
fascia, functions of, 1246
pleura, relations to chest wall, 1139
popliteal space, 1225
vessels, 1227
Poupart's ligament, 1166
pudic artery, 1219
radial artery, 1197
nerve, 1197
rectum, 1155
saphena veins, 1231
saphenous nerves, 1242
scalp, the, 1115
scapula, muscles and arterial anastomoses,
1175
sciatic artery, 1219
shoulder, the, 1180
skin folds or creases of the palm, 1199
spinal accessory nerve, 1130

INDEX
1303
SUR
Surgical and topographical anatomy of-
spinal nerves, origin of, 1175
spleen, 1148
sterno-clavicular joint, structures behind,
1127
sterno-mastoid muscle, 1126
stomach, 1146
Syme's amputation, lines of incision, 1238
synovial membranes of foot, 1241
of hand, 1207
of knee, 1223
tendo Achillis, where divided, 1237
tendons around ankle, arrangement of, 1233
tenotomy, guides for, at ankle, 1237
thenar and hypothenar eminences, 1199
thigh, the, 1210
thoracic vessels, relations to chest wall,1141
thorax (superficial), 1134
tibial artery, posterior, 1231
tibialis anticus muscle, 1247
tendon, 1238
posticus muscle, 1247
tendon, 1238
toes, great, lines for amputation of, 1240
tonsils, 1122
trapezius muscle, 1174
triangle of Petit, 1175
triceps muscle, 1188
ulnar artery in forearm, 1195
nerve, 1188, 1196
umbilical hernia, congenital, 1169
infantile, 1169
of adult life, 1170
ring, changes in adult life, 1169
vessels, changes in adult life, 1169
urachus, 1163
urethra, the, 1152
valves of heart, topography of, 1140
viscera and visceral regions, 994
behind linea alba, 1145
relations of, to vertebræ, 1176
wrist and hand, the, 1198
Suspensory [sub = under; pendo- I hang]
ligament, central odontoid, 200
origin from sheath of notochord, 295
of eyeball, 895
of lens, 880, 886
of malleus, 74, 914
of penis, 1070
of thyroid, 954
Sustentaculum [sustento I support] hepatis,
1008
=
tali [talus the astragalus], 173
=
=
Sutures [sutura a seam], varieties of, true,
false, and grooved, 187
basilar, 93
coronal, 50, 75
ethmo-lachrymal, 85
ethmo-sphenoidal, 92
frontal, or metopic, 50, 75
fronto-ethmoidal, 89
fronto-parietal, or coronal, 50, 75
fronto-squamosal, 40, 78
interparietal, or sagittal, 50, 75
lambdoid, 50, 75
malo-maxillary, 84
maxillo-premaxillary, 62, 79
meso-palatine, 62, 79
metopic, 50, 75
neuro-central, 21
Sutures, occipital, 75
SYN
occipito-mastoid, 93
occipito-parietal, or lambdoid, 50, 75
parieto-mastoid, 78, 93
petro-occipital, 93
petro-sphenoidal, 92
petro-squamosal, 38
sagittal, 50, 75
spheno-malar, 78
spheno-parietal, 78, 92
squamo-sphenoidal, 78, 92
squamous, 50, 78, 92
transverse, 87
palatine, 79
zygomatic, 78
Sylvian point of skull, 768
Sylvius, aqueduct of, 749
fissure of, 722
fossa of, 722, 729
ventricle of, 743
Syme's amputation, incisions for, 1238
Sympathetic, gangliated cords of, 864
cervical portion of, 864
cranial portion of, 864
lumbar portion of, 869
sacral portion of, 869
thoracic (dorsal) portion of, 868
See also Plexus, sympa-
nerves, the, 863.
thetic
of orbit, 901
root of lenticular ganglion, 797, 865
of otic ganglion, 805
Symphysis [oúv = together;
[ouv-together; púw I grow]
pubis, the, 218
Synarthrosis [ouv-together; apopov = a joint],
classes of, 188
definition of, 187
examples of, 188
Synchondrosis [oúv; xóvopos = cartilage], sacro-
iliac, 211
Synovial membrane
of acromio-clavicular
articulation, 231
of ankle joint, 281
of astragalo-scaphoid joint, 288
of atlanto-axoidean joint, central, 197
lateral, 196
of calcaneo-astragaloid joint, anterior,
285
posterior, 283
of calcaneo-cuboid joint, 288
of carpo-metacarpal joints, 253
joint of thumb, 254
of carpus, 251
of costo-central articulation, 221
of costo-transverse articulation, 222
of cubo-metatarsal (outer tarso-meta-
tarsal) joint, 292
of elbow joint, 240
of hip joint, 263
of interchondral articulation, 225
of intermetatarsal joints, 292
of interphalangeal joints, 258
of knee joint, 272; surgical anatomy
of, 1223
of metacarpo-phalangeal joints, 257
of occipito-atlantal articulation, 194
of radio-carpal joint, 247
of radio-ulnar joint, superior, 242
of shoulder joint, 236
of sterno-clavicular articulation, 229
1304
INDEX
SYN
Synovial membrane of tarso-metatarsal joints,
middle, 291
outer (cubo-metatarsal), 292
of temporo-mandibular (maxillary)
articulation, 190
of tibio-fibular joint, inferior, 279
superior, 278
of vertebral articular processes, 205
membranes of foot, surgical anatomy of,
1241
of joints of hand, surgical anatomy of,
1209
of tendons of hand, surgical anatomy
of, 1207
Systemic arteries, the, 495; veins, 638
TABATIÈRE [snuff-box] anatomique, 1210
Tænia [Tavía = a band] hippocampi, 738
semicircularis, 741
Tæniæ tectæ [tectus = roofed], 734
Tail of nucleus caudatus, 740
of pancreas, 1023
Tapetum [tapete = a carpet], 735
Tarsal arteries, internal and external, 636
cartilages, 875, 903
e ligament (palpebral), external, 456, 904
internal, 455, 904
Tarso-metatarsal joints, internal, 290
middle, 291
outer(cubo-metatarsal),291
Tarsus [Tapoós a broad surface], bones of, 137
of eyelids, 875, 903
Teeth, the, 94
milk, 96
permanent, 94
relations of crowns of upper to lower, 96
Tegmen [= a roof] tympani, 39, 42, 93
of crura cerebri, 752
Tegmental, or red nucleus, 752
region of pons, 760
Tela [a web] choroidea, inferior, 716, 757
superior, 743
Temporal [tempora- the temples] artery (=
superficial), 521; topography of,
1117
deep, anterior and posterior, 526
middle, 522
of posterior cerebral, 544
bone, 37
ossification of, 45; at birth, 101
convolutions of brain, 729
fascia, 468
fissures of brain, 728
fossa, 76
lobe of cerebrum, 728
lymphatic vessels, 692
muscle, 469
nerves of facial, 810
of mandibular division, 802
superficial, of auriculo-temporal, 803
of temporo-malar, 798
ridges, 48, 76
veins, common, 652
deep, 653
middle, 652
superficial, 652
of diploë, 656
Temporo-facial division of facial nerve, 810
Temporo-malar nerve, 798
THO

Temporo-mandibular (maxillary) articulation,
189
Temporo-maxillary vein, 653
Temporo-occipital artery, 544
Tendino-trochanteric band, 261
Tendo [tendere to stretch] Achillis, 395; where
divided, 1237
oculi, 455, 874, 904
Tenon's capsule, 897
space, 897
Tenotomy, guides for operation at ankle, 1237
Tension curves of cancellous bone, 4
Tensor palati muscle, 981
tarsi muscle, 457
tympani muscle, 915
vaginæ femoris muscle, 373
Tenth cranial (= pneumogastric) nerve, 815
rib, 110
Tentorial groove of uncinate gyrus, 732
surface of cerebral hemispheres, 730
Tentorium [= a tent] cerebelli, 714
Teres [=round] major muscle, 320

minor muscle, 319
Testes of corpora quadrigemina, 751
Testicles [dim. of testis], the, 1061
lymphatics of, 702
structure, 1064
vessels and nerves of, 1067
Testicular artery of spermatic, 596
Thalamencephalon, the, 709, 745
nerve tracts in, 784
Thalamic [0áλapos = a bed] arteries, middle, 533
Thebesius, foramina of, 967, 970
valve of, 967
=
Theca [Onna case] of flexor tendons of hand,
352

Thenar [0évap= the palm of the hand] eminence,
muscles of, 358
surgical anatomy of, 1199
fascia, 352
Thigh, muscles and fascia of, 364
surgical anatomy of, 1210
Third cranial (oculo-motor) nerve, 791
foramen for, 93
trochanter, 157
Thoracic artery, acromial, 555
alar, 555
axis, 555
long, 555
short or superior, 555
twelfth or subcostal, 581
duct, 688, 698; variations, 699
inlet, 117
lymphatics, 695
nerves, anterior, external and internal, 835
posterior, 834
cardiac, 819
spinal, primary divisions of,
anterior, 843
posterior, 827
first, 843; variation, 843
last or twelfth, 846
portion of gangliated cord, 868
veins, 638, 682
twelfth, 645
vessels, relations to chest wall, 1141
Thorax [0úpa = a breastplate], the, 934
aperture of, lower, 935
upper, 934
structures passing through, 1136
INDEX
1305
THO
Thorax, mediastina of, 935
movements of, 226
skeleton of, 117
surgical anatomy of, superficial, 1134
viscera contained in, 935
Thymic arteries, 548
veins, 641
Thymus [= thyme] body or gland, 955
lymphatics of, 697
structure of, 956
vessels and nerves of, 697
Thyro-arytenoid ligaments, inferior (true) and
superior (false vocal cords), 944
muscle, 946
Thyro-epiglottidean ligament, 942
Thyro-epiglottideus muscle, 947
Thyro-glossal duct, 954
Thyro-hyal centre of ossification, 103
Thyro-hyals, 73
Thyro-hyoid ligaments, 943
membrane, 943
muscle, 477; nerve to, 821
Thyroid [Oupeós = a shield] artery, inferior, 545
superior, 512; branches, 513
axis, 545
bar, 97
body, or gland, 952
ligaments of, 954
structure of, 954
vessels and nerves, 867, 955
cartilage, 939
foramen (=obturator), 148, 153
lymphatics, 692
veins, middle, 666
inferior, right and left, 666
superior, 666
Thyroidea ima [ima= lowest] artery, 504
Tibia [a pipe or flute], the, 163
ossification of, 167
surgical anatomy of, 1222
Tibial arteries, anterior, 632; surgical anatomy
of, 1233
posterior, 626; surgical ana-
tomy of, 1231
recurrent, anterior and pos-
terior, 634
nerves, anterior, 859; branches, 860
posterior, 862; branches, 862
Tibialis anticus muscle, 410
tendon, effect on plantar arch, 1247
where divided, 1239
posticus muscle, 398
tendon, effect on plantar arch, 1247
where divided, 1239
Tibio-fascialis anticus muscle, 490
Tongue, the, 929
arteries and nerves of, 925
lymphatics of, 691
mucous membrane and papillæ of, 921
muscles of, 925
septum of, 925
Tonsillar arteries of ascending palatine, 517
of facial, 517
lobe of cerebellum, 755
nerves of glosso-pharyngeal, 815, 982
recess, 980
Tonsils, the, 982
surgical anatomy of, 1122
vascular and nerve supply, 982
pharyngeal, 987
TRI

Tooth, component parts of, 94
Topographical Anatomy, see Surgical and
topographical anatomy
Topography, cranio-cerebral, 766
of spinal nerves, 823
Torcular [=a wine press] Herophili, 27, 658
Trabeculæ [dim. of trabs = a beam] of testis,
1064
Trabecular region in the chondral skull, 97
Trachea [Tpaxús = rough], the, 950
structure of, 951
vascular and nervous supply, 952
Tracheal artery of inferior thyroid, 546
layer of deep cervical fascia, 1133
lymphatic glands, 697
vessels, 692
triangle, or inferior carotid, 1129
Trachealis muscle, 952
Trachelo-mastoid [Tpáxnλos = the neck] muscle,
443
Tract, or Tracts, direct cerebellar, 781
of the fillet, 782
frontal pontine, 785
Gower's, 781
nerve-, in thalamencephalon and prosence-
phalon, 784
olfactory, 788; cortex of, 788
pyramidal, anterior and lateral, 780*
of spinal cord 779
uveal, 882
Tractus intermedio-lateralis, 778
spiralis foraminulentus, 917
Tragicus muscle, 909
Tragus [Tpayos a goat], the, 908
Transversalis abdominis muscle, 433
colli artery (see Transverse cervical), 546
muscle, 443
fascia, 436
humeri artery (see Subscapular), 546
Transversus auris muscle, 909
nucha muscle, 304, 490
pedis muscle, 407
perinæi muscle, deep, 1079, 1106
superficial, 1072, 1079, 1107
Trapezium [Tpáre (a = a table], the, 141
Trapezius muscle, 302; nerve to, 831
surgical anatomy of, 1174
Trapezoid [τράπεζα = a table; eldos = like]
bone, 141
ligament, 231
Triangle of neck, anterior, 1127
carotid, superior and inf., 1129
posterior, 1129
submaxillary, 1127
of perinæum, rectal, 1151
urethral, 1151
of Petit, 1175
Scarpa's, surgical anatomy of, 1213
Triangular fascia, 429
fibro-cartilage of wrist, 243
fossa (= fossa of antihelix), 908
ligament, inferior (= anterior layer), 1105
superior or deep (=posterior layer),
1106
space at base of bladder, 1055
Triangularis sterni muscle, 421
Triceps [tres-three; caput = head] extensor
cubiti muscle, 326; nerve to, 841
surgical anatomy of, 1188
suræ muscle, 391
1306
INDEX
TRI
Tricipital artery of posterior circumflex, 558
Tricuspid [tres-three; cuspis a point] valve,
970; topography of, 1140
Trigeminal foramen, 38, 104
nerve (fifth cranial), 794
notch, 38
Trigone [Tpeis = three; ywvía - an angle], the,
1057
=
Trigonum habenula [dim. of habena a rein],
746
hypoglossi, 758
os, 172
vagi, 758
Triradiate fissure of cerebrum, 725
Triticeo-glossus muscle, 490
Trochanteric fossa, 157
=
Trochanters [Tpoxάw I roll] of femur-
=
greater, 156; surgical anatomy of, 100
lesser, 157
third, 157
Trochlea [Tpoxixia = a pulley], the, 129
of superior oblique muscle, 893
Trochlear artery of lachrymal, 531
nerve, or fourth cranial, 793
Trochoides [7poxós a wheel], definition and
examples of, 188
True ligaments of bladder, 1056
pelvis, 155
ribs, 106
vocal cords, 949
Tubal artery, 1092
Tube, collecting, of kidney, 1048
of epididymis, 1065
looped, of Henle, 1048
Tuber cinereum, 748
omentale of liver, 1015
valvulæ, 755
Tubercle, accessory, of lumbar vertebræ, 14
adductor, 157
of atlas, anterior and posterior, 8
for transverse ligament, 9
of calcaneum, anterior, inner and outer, 174
cervical, of femur, superior and inferior, 156
condyloid, of mandible, 70
deltoid, of clavicle, 118
genial, 68
lachrymal, 62
laminated, of cerebellum, 755
Lisfranc's, 108
mammillary, of lumbar vertebræ, 13
of optic thalamus,anterior and posterior,746
orbicular, of incus, 75
peroneal, of calcaneum, 174
pharyngeal, of basi-occipital, 29, 82
post-glenoid, 38
of rib, 106
of Rolando, 761
of tibia, 163; surgical anatomy of, 1222
Tubercles of Montgomery, 1109
Tuberculum [dim. of tuber] acusticum, 758, 812
Tuberosity, bicipital, 135
of clavicle, 118
of fifth metatarsal, 182
of humerus, greater and lesser, 124
of ilium, 148
of ischium, 149
of maxilla, 60, 79
of palate bone, 64
of scaphoid, carpal, 138
tarsal, 176
UMB

Tuberosity of tibia, 163
Tubules, uriniferous, 1048
Tubuli recti of testis, 1064
seminiferi, 1064
Tunica albuginea of ovary, 1090
of penis, 1070
of testis, 1064
propria of kidney, 1047
vaginalis, 1062
vasculosa of testicle, 1064
Turbinal process of lachrymal, 58
Turbinals [turbo = a whirl] (ethmo-turbinals),
inferior, 57; ossification of, 57
at birth, 103
sphenoidal, 56; at birth, 102
superior, 54
=
Turbinated [turbo a whirl: from their coiled
nature] crests of maxilla, 62
of palate bone, 64
Twelfth (last) dorsal artery, 583
cranial or hypoglossal nerve, 820
rib, 110
Tympanic artery of ascending pharyngeal, 511
of internal maxillary, 524, 915
of middle meningeal, 524
of stylo-mastoid, 521
of Vidian, 527
canaliculus, 40, 84
cavity, 912
nerve of glosso-pharyngeal (= Jacobson's),
814, 916
or small deep petrosal, 865, 916
plate, 40, 84
plexus, 916
portion of temporal bone, 37; at birth, 102
vein, 653
Tympano-hyal process, 98; centre of ossifica-
tion, 98
Tympanum [Túμπavov a drum], the, 42, 912
emissary veins from, 1114
measurements of, 45
muscles of, 914
ossicles of, 73, 913
promontory of, 42
proper, 43
roof of, 93
vessels and nerves of, 915
vestibule and semicircular canals of, 44
ULNA [λévn=the elbow], the, 131
ossification of, 134
Ulnar artery, 563; surgical anatomy of, 1195
in forearm, 564; variations, 565
in the palm (superficial palmar
arch), 568; variations, 569
at the wrist, 568
carpal, anterior and posterior, 568
recurrent, anterior and posterior, 565
condyle of humerus (internal), 129
nerve, 840; surgical anatomy of, 1188, 1196
vein, superficial, anterior and posterior,
679
Umbilical fissure of liver, 1014, 1016
hernia, coverings of, 1170
parts concerned in, 1169
varieties of, 1169
ring, changes in, in adult life, 1169
vein, 677

INDEX
1307
UMB
VEI
Umbilical vessels, changes in, in adult life, 1169
Umbilicus, 425
Umbo [the boss of a shield] of membrana
tympani, 911
=
Unciform [uncus a hook] bone, the, 142
process of ethmoid, 54
of unciform bone, 142
Uncinate artery of posterior cerebral, 544
of posterior communicating, 533
convolution (or gyrus), 732
Uncus [ a hook] of uncinate gyrus, 732
Ungual [unguis = a nail] phalanges of fingers,
148; ossification of, 148
of toes, 184; ossification of, 185
Uracheric artery of superior vesical, 604
Urachus [oupov = urine; exw = I hold], the, 1163
Uretal artery (ureteric) of common iliac, 600
of ovarian, 596
of renal, 594
of spermatic, 595
(ureteric) of superior vesical, 604
=
Ureter [oupéw I pass water], 1052
lymphatics of, 705, 1052
structure, 1052
varieties, 1052
vessels and nerves, 1052
Urethra [oupov = urine], the female, 1079
male, 1073; surgical anatomy of, 1152
Urethral triangle of perinæum, 1151
Urinary bladder, the, 1053
development of, 1075
meatus, internal, relation to pelvic wall,
1055
external, 1071
Uriniferous tubules, 1048
Uro-genital sinus, 1095
Uterine artery, 605, 1091
of ovarian, 596
plexus (nerve), 873, 1092
vein, 1091
Utero-inguinal (round) ligament, 1088
Utero-ovarian ligaments, 1088
Utero-pelvic ligaments, 1088
Utero-sacral ligaments, 1087, 1088
Utero-vesical ligaments, 1087
Uterus [the womb], the, 1081
ligaments, 1085
lymphatics of, 702
nerves of, 873, 1092
structure of, 1084
variation according to age, 1084
masculinus, 1074
Utricle [dim. of uterus], the, 918
Uveal [uva a grape] tract, 882
Uvula [dim. of uva] of cerebellum, 755
of Lieutaud, 1058
of palate, 980
VAGINA [= a sheath], the, 1079
form and direction, 1079
lymphatics, 702, 1081
relations, 1080
structure, 1081
vessels and nerves, 1081
Vaginal arteries, 606
azygos artery, 606
plexus (nerve), 873
process of temporal bone, 40, 84
=
Vagus [vago I wander] (= pneumogastric)
nerve, 815
Valentin, ganglion of, 799
Vallecula of cerebellum, 753
of tongue, 921
Valsalva, sinuses of, 497, 969
Valve, Eustachian, 966; in fœtus, 977
of foramen ovale (in foetus), 977
ileo-cæcal, 1007
of Thebesius, 967
of Vieussens, 757
Valves of heart, bicuspid (or mitral), 972
semilunar, aortic, 972
pulmonary, 969
tricuspid, 970; topography of, 1140
Valvulæ conniventes [= lying close together]
of intestine, 1004
Vas [= a vessel] aberrans, of Haller, 1065
deferens, the, 1065
artery to, 604
nerves to, 873
Vasa brevia of splenic artery, 592
veins, 676
efferentia, 1064
intestini tenuis, 594
Vascular coat of eyeball, 882
Vastus externus muscle, 388
internus and crureus, 388; division be
tween the two muscles, 389
Vater, ampulla of, 1020
Vein, or Veins, divisions of the, 638
of abdomen, 669
acromial thoracic, 682
angular, 650
auricular, anterior and posterior, 653
of heart, left, 646, 974
axillary, 682
right, 647
azygos major, 642
minor et tertia, 644
basilar, 662
basilic, 681
brachial, 682
median, 680
brachio-cephalic, 640; variations, 642
of brain, 661
bronchial, 645, 962
buccal, 651, 653
capsular, or suprarenal, 671, 1051
cardiac, anterior, 647, 974
great, 646, 973
posterior, 647, 974
small, 647
smaller anterior, 648
central, of retina, 664
cephalic, 680
cerebellar, inferior, 663
superior, 662
cerebral, 661
central or deep, 662
cortical, 661
cervical, deep, 652, 666
transverse, 654
choroid, 662
ciliary, anterior and posterior, 664
lower posterior, 665
circumflex iliac, deep, 687
superficial, 669, 685
of shoulder, 682
coronary, of heart, 646, 973
1308
INDEX
Vein, or Veins-
VEI
coronary, of lips, inferior and superior, 651
of stomach, 674
of cranium, see Sinuses
cystic, 674
dental, inferior (= mandibular), 653
posterior, 653
diaphragmatic, or phrenic, 672
digital, of foot, 683
of hand, 679
of diploë, 655
dorsal, spinal, 667
of penis, 677
of ear, 663
Aemissary, of cranium, 711
of mastoid, 659, 711
emulgent, 670
epigastric, deep, 687
superficial, 669, 685
ethmoidal, anterior and posterior, 664, 934
extra-spinal, 667
facial, common, 650
communicating, 650, 651
transverse, 652; variations, 651
femoral, common, 686
cutaneous, external and internal, 685
deep, 686
of foot and leg, 685
frontal, 649
of diploë, 655
fronto-sphenoidal, of diploë, 655
of Galen, of brain, 662, 743
of heart, 647, 974
gastric (coronary), 674
gastro-epiploic, left, 676
right, 675
glandular (= submaxillary), 651
gluteal, 677
hæmorrhoidal, 678
of head and neck, deep, 655
superficial, 648
of heart, 646
hemiazygos, 644
accessoria, 644
hepatic, 672, 1019
iliac, common, 672; variations, 673
external, 686
internal, 677
ilio-lumbar, 672, 677
innominate, 640; variations, 642
intercostal, superior, 641, 645
interventricular, anterior, 646
posterior, 647, 974
intra-spinal, 668
jugular, anterior, 655
external, 654; variations, 654
internal, 665
posterior external, 654
jugulo-cephalic, 683
labial, inferior and superior, 651
lachrymal, 664
of lower extremity, deep, 685
laryngeal, 665
lingual, 665
superficial, 683
lumbar, 671
ascending, 671
mammary, internal, 640
mandibular, 653
marginal, left and right, 647, 974
VEI
masseteric, 651, 653
mastoid emissary, 659, 711
maxillary, internal, 653

anterior, 651
median basilic, 680
cephalic, 679
deep, 679, 682
superficial, 679
mediastinal, 641
of medulla oblongata, 663
medullary or medulli-spinal, 668
meningeal cranial, middle, 653
spinal, extra-medullary, 668
mesenteric, inferior, 676
superior, 674

80 nasal, 663
lateral, superior and inferior, 650
transverse, 649
of neck, deep, 665
superficial, 654
oblique, of Marshall, 647, 963, 974
obturator, 677
occipital, 651
of diploë, 656
œsophageal, 645
ophthalmic, common, 663
inferior, 653, 664
superior, 663
of orbit, 663, 900
orbital, 652

ovarian, 671, 1092
palatine, inferior or descending, 651
superior, 653
palpebral, inferior, 651
superior, 650
pancreatic, 676
pancreatico-duodenal, 675
parietal, external, of diploë, 656
parieto-occipital of diploë, 656
parotid, 651, 653
of pelvis, 676
pericardiac, 641
peroneal, 685
pharyngeal, 665
phrenic, inferior, 672
plexuses of, see Plexuses, venous
of pons Varolii, 663

popliteal, 686; surgical anatomy of, 1227
variations, 686
portal, 673
preventricular, 648, 974
profunda, 686
pterygoid, 653
pudic, 677, 1106
pulmonary, 639
pyloric, 674
radial, superficial, 679
renal, 670
sacral, middle, 672; lateral, 677
saphenous, long or internal, 683; surgical
anatomy of, 1231
short or external, 685; surgical
anatomy of, 1228, 1231
of scalp and face, superficial, 648
sciatic, 677
spermatic, 671
spheno-palatine, 653, 934
spinal, 667
of spinal cord, 668
splenic, 675

INDEX
1309
Vein, or Veins--
VEI
subclavian, 682; variations, 683
subcostal, 645
submaxillary, 651
submental, 651
subscapular, 682
supra-orbital, 650, 653
suprarenal, 671, 1051
suprascapular, 654
systemic, 638
temporal, common, 652
deep, 653
middle and superficial, 652
of diploë, 656
temporo-maxillary, 653
thoracic, long, 682
of thorax, 638
thymic, 641
thyroid, 666
tibial, 685
tympanic, 653
ulnar, superficial, 679
umbilical, 677
of upper extremity, deep, 682
superficial, 678
uterine, 1091
vasa brevia, of splenic, 676
vertebral, 666
of vertebræ (bodies), 668
Vesalian, 653
Vena azygos major, 642
minor, 644
tertia, 644
cava inferior, 669
fissure in liver for, 1016
variations, 672
superior, 639; topography of, 1141;
variations, 642
corporis striati, 662
Galeni (cardiac), 647, 968
hemiazygos, 644
accessoria, 644
magna Galeni (cerebral), 662, 743
portæ, see Portal vein
salvatella, 679
Venæ basis vertebræ, 668
comites, brachial, 682
tibial, 685
cordis minimæ, 646, 968
parvæ, 648
vorticosæ [vortex = a whirlpool], 881,
889
Velum [a veil] interpositum, 743
medullary, of cerebellum inferior, 755, 757
superior, 757
Venous side of heart, 965
Ventricle [dim. of venter = the belly] of Aran-
tius, 758
of brain, lateral, 709, 735
fifth (Sylvian), 709, 743
fourth, 709, 756
third, 709, 745
of heart, left, 971
right, 968
of larynx, 948
Ventricular walls of foetal heart, 977
Ventriculus terminalis of cord, 778
Verheyen, stars of, 1049
Vermiform [vermis = a worm] artery of pos-
terior inferior cerebellar, 542
VOL
Vermiform artery of superior cerebellar, 543
fossa (basis cranii), 27, 93
process of cerebellum, inferior, 755
superior, 754
Vertebra [vertere to turn: from its rotatory
motion], anti-clinal, 13
body of, morphology of, 25
cervical, peculiar, 8; typical, 7
half-vertebra, 13
lumbar, peculiar, 15; typical, 13
neural arch of, morphology of, 25
ossification of, 20
prominens, 9; muscles attached to, 11
ossification of, 20
sacral and coccygeal, 15, 18
thoracic or dorsal, peculiar, 13; typical,
12
typical, 6
Vertebral aponeurosis, 433
artery, 540; variations, 541
branches to, from middle cervical
ganglion, 868
of deep cervical, 551
of lumbar, 588
column, arterial and nerve supply and
movements of, 207
ribs, 106
veins, 666
Vertebro-chondral ribs, 106
Vertebro-sternal ribs, 106
Verumontanum [veru a ridge], 1074
Vesalian vein, 653
1
Vesical [vesica = a bladder] arteries, 604
of obturator artery, 606
lymphatics, 702
nerves, 873
plexus, nerve, 873
venous, 678
portion of ureter, 1053
=
Vesicles [dim. of vesica a bladder], cerebral,
anterior, middle, and posterior, 708
Vesico-pubic muscle, 1056
Vesiculæ [dim. of vesica = a bladder] semin-
ales, 1066
Vestibular artery of stylo-mastoid, 521
nerve, 813
Vestibule of labyrinth, 44, 916
of mouth, 979
of nostrils, 926, 931
of vagina, 1077
Vestigial bones (e.g. fibula), 169
fold of pericardium, 963
Vicq d'Azyr, bundles of, 743, 748, 784
foramen cæcum of, 761
Vidian artery, 527
canal, 35, 77, 107; at birth, 101
nerve, 800
Vieussens, valve of, 757
Villi [villus-shaggy] of small intestine, 1004
Vincula [= small chains] accessoria, 352
Viscera [viscus, pl. viscera an organ], ab-
dominal, the, 989
relations of, to vertebræ, 1176
Visceral branches of abdominal aorta, 588
of sacral plexus, 855
lymphatics of pelvis, 702
of thorax, 697
Vitreous [vitrum=glass] humour, 886
Vocal cords, true and false, 949
=
Volar [vola the palm] artery, superficial, 574
1310
INDEX
VOM
Vomer [a ploughshare], 58
ossification of, 59
at birth, 103
Vulva [volvere to roll], the, 1076
WALDEYER'S glands of eyelids, 903
Wharton's (submaxillary) duct, 984
White line of obturator fascia, 1099
matter of cerebellum, 756
of encephalon, 718
Wings of sphenoid, greater and lesser, 33
Winslow, foramen of, 990
Wirsung, canal of, 1024
Wisdom teeth, 96.
Wolffian body, 1093
duct, 1092
Womb, the, 1081. See Uterus
Wormian bones, 53
Wrisberg, cardiac ganglion of, 975
cartilages of, 943
nerve of, 835
Wrist, surgical anatomy of, 1197
joint, the, see Radio-carpal articulation
ZYG
XIPHOID [Sipos = a sword; eidos = like] artery
of superior epigastric, 550
cartilage, 113

YELLOW elastic fibres of trachea, 952
spot of eye, 878
ZEISS's glands of eyelids, 903
Zone, boundary, of Lissauer, 782
mixed lateral, of spinal cord, 781
of uterus, intravaginal, 1084
supravaginal, 1083
[ζυγός
of vaginal attachment, 1084
Zygoma [vyósa yoke: the union between
the facial bones and those of the side
of the head], the, 37
relation of, to cranial contents, 767
Zygomatic fossa, 76; lymphatics of, 691
process of malar bone, 67
region, 79
suture, 78
Zygomatico-orbital artery, 522
Zygomaticus major muscle, 464
minor muscle, 467






NP. Chase.
51.8. Ann, 217

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