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MANUAL
OF
Practical Anatomy
BY
D. J. CUNNINGHAM,
M.D. (EDIN. ET DUBL.), D.SC, LL.D. (ST. AND. ET GLAS.), D.C.L. (OXON.), F.R.S.,
PROFESSOR OF ANATOMY IN THE UNIVERSITY OF EDINBURGH ^
VOLUME FIRST
UPPER LIMB; LOWER LIMB; ABDOMEN
FOURTH EDITION
ILLUSTRATED WITH 237 ENGRAVINGS, MANY IN COLO
NEW YORK
WILLIAM WOOD AND COMPANY
1908
PREFACE TO FOURTH EDITION
In the preparation of the present edition of the Manual of
Practical Anatomy the text has been revised and several parts,
chiefly in the chapters dealing with the abdomen and thorax,
rewritten. A large number of new illustrations have likewise
been added to both volumes. These are the work of Mr. J. T.
Murray, to whom the author owes so much for the assistance
he has given in the preparation not only of this edition, but
also of the previous editions of the book. The dissections from
which the drawings have been taken were prepared specially
for the purpose by Dr. R. B. Davidson, Mr. A. Ninian Bruce,
Mr. A. W. Burton, Mr. G. F. Fismer, Mr. J. K. M. Dickie,
and Mr. D. C. Adam. The author is deeply indebted to
these gentlemen for the valuable and skilful help they have
so cheerfully rendered. Nor must he omit to express his
indebtedness to Dr. E. B. Jamieson, Lecturer in the Depart-
ment of Anatomy, for assisting him in the correction of the
proofs.
18 Grosvenor Crescent,
Edinburgh, March 19, 1907.
Digitized by the Internet Archive
in 2010 with funding from
Columbia University Libraries
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PREFACE TO THE THIRD EDITION.
The Manual of Practical Anatomy as it is now issued differs
very considerably from previous editions. The text has been
revised ; many details which are not essential have been cut
out, whilst at the same time the author has endeavoured to
make the descriptive matter more concise. The book there-
fore has not grown in bulk.
The sections in which the chief changes will be manifest
are those which treat of the thoracic and abdominal viscera.
At the time when the first edition was issued, our ideas of
the form and relationships of the various viscera were under-
going rapid evolution. The value of the models prepared
under the supervision of Professor His had received full
recognition, and attempts were being made in various quarters
to verify his results by similar and other methods. In the
preface to that edition the author took the opportunity of
pointing out that such specimens and models could only be
regarded as giving one of the many different forms which are
assumed by internal organs in connection with changes in
the attitude of the body, and in connection with the alterations
which are constantly going on in the living individual in the
state of the hollow viscera. It was something, however, to
be able to describe with some near approximation to truth
the form of the viscera under certain given conditions, even
although these conditions might be only repeated in life when
the body was in the horizontal position, and when one
vii
viii PREFACE TO THE THIRD EDITION
particular phase of the hollow viscera was present. In the
same preface the author ventured to express the belief that
before long more extended research would greatly enlarge our
knowledge of the alterations in neighbouring organs which
are produced by changes in the degree of expansion or
contraction of the hollow viscera. How amply this belief has
been warranted is seen in the work of Symington, Young,
Birmingham, Addison,- Huntington, Robinson, Dixon, Keith,
Hepburn, and others. Formalin has been a powerful agent in
the hands of these observers; and it so comes about that in
the present edition, and largely through the labours of these
Anatomists, it has been possible to correct many erroneous
impressions on this subject, and also to speak with greater
confidence, and with the increased clearness which such con-
fidence brings, upon the topography of the viscera.
But perhaps the most noticeable feature of the present
edition will be found in the illustrations. The great majority
of the old figures have been withdrawn, and these have been
replaced by others which are not only more suitable for the
purpose for which they are intended, but also distinctly superior
from the artistic point of view. In carrying out this part of
the work the author has been so fortunate as to have had
the services of Mr. J. T. Murray, an artist who has obtained
an almost unrivalled reputation in the treatment of anatomical
subjects. Several of the illustrations have been taken from
the recently published Text-book of Anatomy, and the author
has to express his indebtedness to the writers of the various
articles which have furnished these for the ready manner in
which they allowed their figures to be used for this purpose.
The sources from which all borrowed illustrations are taken
are in every case indicated in the text.
March 1903.
CONTENTS.
THE UPPER LIMB.
Introductory, .
Dissection of the Back,
Pectoral Region and Axillary Space,
Axilla, .
Shoulder— Scapular Region, .
Front of the Arm,
Back of the Arm,
Shoulder-Joint, .
Forearm and Hank,
Front and Inner Border of the Forearm,
Wrist and Palm, .
Back and Outer Border of the Forearm,
Dorsal Aspect of the Wrist and Hand,
Articulations, .
l'AGE
I
2
13
23
42
55
76
82
88
90
103
124
133
139
THE LOWER LIMB.
Gluteal Region, .
Popliteal Space, ..•••••
Back of the Thigh, .
Front of the Thigh, .
Superficial Dissection of the Front of the Thigh,
Deep Dissection of the Front of the Thigh,
Inner Side of the Thigh, .
Hip-Joint, ...•■•
The Leg, ..-•••
VOL. I — a 2 IX
157
174
I85
190
191
20I
224
235
24I
CONTENTS
Anterior Tibio-Fibular Region— Dorsum of Foot,
Peroneal Region,
Tibial Region,
Posterior Tibio-Fibular Region.
Sole of the Foot,
Knee-Joint,
Ankle-Joint,
Tibio-Fibular Joints,
Articulations of the Foot,
PAGE
243
256
258
259
272
292
304
308
3"
ABDOMEN
Male Perineum, .
Rectal Triangle,
Urogenital Triangle,
Female Perineum,
Rectal Triangle,
Urogenital Triangle,
Abdominal Wall,
Surgical Anatomy of the Abdominal Wall,
Abdominal Cavity and its Contents, .
Vessels on the Posterior Wall of the Abdomen,
Fascia and Muscles on the Posterior Wall
Abdomen, ....
Nerves on the Posterior Wall of the Abdomen,
Pelvis, .
Male Pelvis,
Pelvic Articulations,
Female Pelvis, .
of the
322
326
33i
345
35o
35o
357
396
404
500
508
5io
5i6
517
575
582
INDEX
605
LIST OF ILLUSTRATIONS,
FIG.
1. Lines of incision for reflection of skin from dorsal aspect of
subject, ......
2. Dissection of the Superficial Muscles and Nerves of the Back,
3. Upper Surface of the Right Clavicle,
4. Diagram of the Lumbar Fascia,
5. Lines of incision for reflection of skin from ventral aspect of the
subject, ......
6. Dissection of the Mammary Gland,
7. Section through a Mammary Gland,
8. The Lymphatic Glands and Vessels of the Axilla and Mammary
Gland. (From Poirier and Ct'XEO— modified),
9. Diagram of section through the Axilla of the Left Side,
10. The Lymphatic Glands and Vessels of the Axilla and Mammary
Gland. (From Poirier and Cuneo — modified),
11. Diagram to show relation of Brachial Nerves to Axillary-
Vessels, ......
12. Diagram of the Costo-coracoid Membrane,
13. The Axillary Artery and its Branches,
14. Under Surface of the Clavicle with the Attachments of the
Muscles mapped out, ....
15. Diagram of the Brachial Plexus,
16. Serratus Magnus Muscle and origin of the Fxternal Oblique-
Muscle, ......
17. Ventral aspect of the Scapula with the Attachments of Muscles
mapped out, ......
18. The Deltoid Muscle and the outer aspect of the Upper Arm,
19. Dissection of the Posterior Scapular Region,
20. Diagram of the Circumflex Vessels and Nerve,
21. Dorsum of Scapula with Attachments of the Muscles mapped out
22. Relation of bones of Elbow to the surface,
23. Relation of the bones of the Elbow to the surface,
24. Cutaneous Nerves on the Front of the Upper Limb,
\i
3
5
7
9
15
18
19
21
24
27
29
30
34
35
37
40
41
44
46
48
49
56
56
59
LIST OF ILLUSTRATIONS
PAGE
Cutaneous Nerves on the Posterior Aspect of the Upper Limb, 61
Diagram to show the arrangement of the Intermuscular Septa
in the Arm. (Turner), . . . . .64
Transverse section through the Lower Third of the Right
Upper Arm, ....... 65
Transverse section through the middle of the Right Upper
Arm, ........ 67
Diagram to show relation of Musculo-spiral Nerve to the
Humerus and of Vessels and Nerves to the Intermuscular
Septa, ....... 69
Anterior aspect of Humerus with Muscular Attachments mapped
out, ........ 72
The Deltoid Muscle and the outer aspect of the Upper Arm, . 73
Dissection of the Antecubital Fossa, . . . -75
Posterior aspect of Humerus with Attachments of Muscles
mapped out, ....... 77
Dissection of the Posterior Aspect of Upper Arm, . . 79
Coronal or vertical transverse section through the Left Shoulder-
joint, ........ 82
Shoulder-joint as seen from the front, . . . .84
Capsular Ligament cut across and Humerus removed, . . 86
Transverse section through the Upper Third of the Left
Forearm, ....... 93
Dissection of the front of the Forearm, . . . .96
Anterior aspect of Bones of Forearm with Muscular Attachments
mapped out, ....... 101
Diagram of Nerves and Vessels of Hand in relation to Bones and
Skin Markings, ...... 104
Superficial Dissection of the Palm, . . . .106
The parts in the Palm which are displayed by the removal of
the Palmar Fascia, . . . . . .110
Transverse section through the Wrist, . . . .114
Diagram to illustrate the arrangement of the Synovial Sheaths
around the Flexor Tendons, . . . . .116
Flexor Tendons of the Finger with Vincula Accessoria, . 117
Palmar aspect of Bones of Carpus and Metacarpus with Muscular
Attachments mapped out, . . . . .120
Dorsal aspect of Bones of Carpus and Metacarpus with Muscular
Attachments mapped out, . . . . .126
Posterior aspect of Bones of Forearm with Attachments of
Muscles mapped out, ..... 129
Dissection of the Back of the Forearm and Hand, . . 131
Diagram of Anastomosis around the Elbow-joint, . . 132
Transverse section through Forearm immediately above Wrist -
joint, 135
Arrangement of the Flexor and Extensor Tendons of the
Middle Finger. (Luschka), . . . .136
LIST OF ILLUSTRATIONS xiii
FIG. PAGE
54. Vertical section through Humerus and Ulna at the Elbow-joint, 140
55. Inner aspect of the Elbow-joint, .... 141
56. Anterior aspect of the Elbow-joint, .... 142
57. Carpal Articular Surfaces of the Radius and of the Triangular
Eibro-cartilage of the Wrist, . . . . . 144
58. Orbicular Ligament of the Radius, .... 146
59. Coronal section through Radio-carpal, Carpal, and Carpo-
metacarpal and Intermetacarpal Joints, . . .150
60. Cutaneous Nerves on the posterior aspect of the Lower Limb, . 160
61. Outer aspect of the Innominate Bone with the Attachments of
the Muscles mapped out, . . . . .163
62. Dissection of the Gluteal Region, .... 166
63. Dissection of the Right Popliteal Space, . . .178
64. Transverse section through the Popliteal Space of the Right
Lower Limb, . . . . . .179
65. Popliteal Space, . . . . . .181
66. Popliteal Artery and its Branches, .... 182
67. Dissection of the Back of the Left Thigh, . . . 186
68. Front aspect of Upper Portions of Bones of Leg with Attach-
ments of Muscles mapped out, .... 187
69. Superficial Dissection of the front of the Upper Part of the
Thigh, ....... 193
70. Cutaneous Nerves on the front of the Lower Limb, . .198
71. Diagram to show the arrangement of the three intermuscular
septa and the three osteo-fascial compartments of the thigh.
(After Turner), ...... 200
72. Dissection to show the connections of Poupart's Ligament, . 202
73. Dissection to show the Femoral Sheath and the other Structures
which pass between Poupart's Ligament and the Innominate
Bone, . ...... 205
74. Dissection of Scarpa's Triangle, .... 209
75. Dissection of Hunter's Canal in the left lower limb, . . 213
76. Transverse Section through Hunter's Canal, . . .214
77. Transverse Section through the Middle of the Thigh, . . 215
7S. Muscle- Attachments to the Outer Surface of the Pubis and
Ischium, . . . . . . .221
79. Front Aspect of Upper Portion of Femur with Attachments of
Muscles mapped out, ..... 222
So. Muscle- Attachments to the Outer Surface of the Pubis and
Ischium, ....... 226
81. Profunda Femoris Artery and its Branches, . . .22;
82. Back aspect of Upper Portion of Femur with the Attachments
of Muscles mapped out, ..... 229
83. Dissection of the Front of the Thigh, .... 230
84. Diagram to illustrate the distribution of the Obturator Nerve
and the general disposition of the Adductor Muscles of the
Thigh. (Patersox), . . . . .231
XIV
FIG.
85.
86.
87.
88.
89.
90.
91.
92.
93-
94.
95-
96.
97-
98.
99-
100.
101.
102.
103.
104.
105.
106.
107.
108.
109.
no.
III.
112.
»3-
114.
115.
116.
117.
118.
119.
120.
121.
LIST OF ILLUSTRATIONS
PAGE
Dissection to show the structures surrounding the Thyroid
Foramen of the Innominate Bone, .... 232
Dissection of Hip-joint from the front, . . . 236
Dissection of Hip-joint from behind, .... 239
Diagrammatic representation of the Fascia of the Leg, . 246
Dissection of the Anterior Tibio-Fibular and Fibular Regions, 247
Transverse section through the Calf of the Leg, . . 249
Dissection of the Dorsum of the Foot, .... 252
Dissection of the Dorsum of the Foot, .... 253
Coronal section through the Left Ankle-joint, Astragalus, and
Calcaneum. (Patersox), ..... 255
Cutaneous Nerves on the posterior aspect of the Lower Limb, 260
Posterior aspect of lower portion of Femur with Attachments of
Muscles mapped out, ..... 262
■Deep Dissection of the Back of the Leg, . . . 266
Posterior aspect of Bones of Leg with Attachments of Muscles
mapped out, ...... 268
Dissection of the Inner Ankle, .... 270
Superficial Dissection of the Sole of the Foot, . . 273
Plantar aspect of Tarsus and Metatarsus with Attachments of
Muscles mapped out, ..... 276
Dissection of the Sole of the Foot, .... 280
Second layer of Muscles and Tendons in the Sole of the Foot, 282
Deep Dissection of the Foot, .... 284
Arteries and Nerves of the Sole of the Foot. (Diagram), . 287
The insertions of the Tibialis Posticus and Peroneus Longus
Muscles in the Right Foot. (Patersox), . . . 289
Anastomosis on the front of the Right Knee-joint, . . 290
Dissection of Knee-joint from the front, . . . 293
The External Lateral Ligament of the Knee-joint, . . 294
The Knee-joint. Posterior view, .... 296
Vertical antero-posterior section through the Knee-joint, . 298
The Knee-joint opened from behind by the removal of the
Posterior Ligament, . . . . .301
Parts attached to the upper end of the Right Tibia, . . 303
Articular surfaces of Tibia and Fibula which articulate with
the Astragalus, ...... 304
Ankle-joint dissected from behind, .... 305
Ligaments on the Outer Aspect of the Ankle-joint and on the
Dorsum of the Tarsus, ..... 306
Ankle- and Tarsal-joints from the Tibial Aspect, . . 307
Vertical section through the Foot. (Luschka), . .310
Astragalus removed so as to show the socket for its head, . 312
Plantar Aspect of Tarsal and Tarso-metatarsal Joints, . 314
Outlet of Male Pelvis, ...... 323
Lines of incision for reflection of skin in the dissection of the
Perineum, ....... 324
LIST OF ILLUSTRATIONS
-IG.
22.
'23-
!24.
[25.
[26.
[27.
[28.
[29.
34-
35-
36.
37-
t39-
[40.
[41.
[42.
C43-
[44.
'45-
[46.
[47,
[48.
[49.
So-
52-
53-
54-
[55.
Diagram of the Pelvic Fascia, .
Dissection of the Perineum,
Transverse section through the body of the Penis,
The Root of the Penis and the Triangular Ligament,
Dorsal or attached aspect of the Penis,
Deep dissection of the Perineum,
Vertical section (schematic) through the Pubic Arch, to show
the two perineal compartments,
Deep dissection of the Perineum. (From Gray's Anatomy
Outlet of Female Pelvis,
Female External Genital Organs,
Muscles of the Female Perineum. (Peter Thompson),
Dissection of Female Perineum,
Lines of incision for reflection of skin from the ventral aspect
of the subject, ....
Dissection of Anterior Wall of the Abdomen, .
Crest of the Ilium as seen from above (semi-diagrammatic), with
Attachments of Muscles mapped out,
Dissection of the External Abdominal Ring and the parts in
its vicinity, .....
Dissection to show the connections of the lower part of the
Aponeurosis of the External Oblique Muscle,
Dissection of the Inguinal Region,
Diagram to illustrate the relations of the lower border of the
internal oblique muscle,
Diagram of the Muscular Strata of the Abdomen (the dotted
line represents the Peritoneum),
Deep dissection of the Anterior Wall of the Abdomen,
Transverse section through Abdominal Wall, .
Deep dissection of the Inguinal Region,
Diagrams illustrating the descent of the testicle and the deriva
tion of the tunica vaginalis,
Dissection of the Left Spermatic Cord to show its constituent
parts. (From Waldeyer, modified),
Transverse section through the left side of the Scrotum and
the Left Testicle, ....
The Right Testis and Epididymis. (A. F. Dixon),
Diagram illustrating the Structure of the Testicle. (A. F
Dixon), ......
Diagram to show the different peritoneal relations in an
ordinary inguinal hernia and a congenital inguinal hernia.
Diagram to illustrate the four different varieties of infantil
hernia. (After LOCKWOOD),
Median section through the terminal part of the Penis,
Outline of the Abdominal Cavity as seen in mesial section,
Planes of subdivision of the Abdominal Cavity,
The Abdominal Viscera. (BIRMINGHAM),
xvi LIST OF ILLUSTRATIONS
FIG.
1 56. Anterior Surface of the Liver, ....
[57. The Spleen, ......
58. The CEsophagus, Stomach, and Duodenum,
59. Stomach of a Child, two years of age, .
[60. The Stomach has been removed from its bed so as to display
the recess in which it lies, ....
[61. Outline of the upper aspect of the Stomach of a Child,
[62. Horizontal position of the Stomach in a Child,
[63. From a tracing of a transverse section through the abdomen,
[64. Diagram to illustrate the continuity of the Peritoneum in th
vertical direction in the Female. (Birmingham), .
[65. Section through the Peritoneal Cavity at the level of th
Foramen of Winslow, ....
[66. Section at the level of the Umbilicus through the Intervertebra
Disc between the third and fourth lumbar vertebrae,
[67. The Mesentery, ......
[68. Diagram to show the compartments of the Peritoneal Cavity
of Abdomen, .....
[69. Dissection of the Superior Mesenteric Artery,
70. Dissection of the Inferior Mesenteric Artery, .
[71. Peyer's Patch and Solitary Glands from the intestine of a child
of two years old. (Birmingham),.
72. Caecum which has been distended with air and dried, and
then opened to show Ileo - Csecal Opening and Valve
(Birmingham), .....
;. Ileo-Caecal Opening and Valve from a subject hardened by
formalin injection. (BIRMINGHAM),
74. The Cceliac Axis System of Vessels, .
75. Duodenum, Pancreas, and Kidneys. (From the model by His)
[76. Dissection of Pancreas from behind to show its Ducts
(Birmingham), .....
77. Dissection of the three layers of Muscular Fibres in the Wall
of the Stomach, .....
!. Small portion of the Pyloric part of the Stomach with par
of Duodenum attached, ....
[79. Pyloric Canal and Pyloric Vestibule of the Stomach opened
up by section in the plane of the two curvatures,
[80. The Bile-Papilla in the interior of the Duodenum. (Birming
ham), ......
. The Inferior or Visceral Surface of the Liver, .
82. Posterior Surface of the Liver,
83. Liver, Right Kidney, Spleen, and Stomach, as seen from
behind, ......
[84. Diagram of the Cystic and Hepatic Ducts. (From Gegen
baur, modified), .....
[85. Section through Abdomen at the level of the second Lumba
Vertebra, ......
LIST OF ILLUSTRATIONS xvii
FIG. PAGE
1 86. Right Kidney and Duodenum, .... 489
187. Relations of the Left Kidney and the Pancreas, . . 490
188. Transverse section through Abdomen at the level of the first
lumbar vertebra, . . . . . .491
189. Dissection from behind to show the relation of the two Pleural
Sacs to the Kidneys, ..... 492
190. From a figure by Max Brodel to show the form of the Pelvis
of the Ureter and the Calices, as well as the relation of the
main branches of the Renal Artery to these, . . 493
191. Diagram of two Renal Papillae, .... 494
192. Anterior Surface of Right Suprarenal Capsule, . . 494
193. Anterior Surface of Left Suprarenal Capsule, . . . 495
194. Posterior Surface of the Anterior Wall of the Thorax and
Abdomen, to show the Costal and Sternal Origins of the
Diaphragm on the left side. (From Luschka's Anatomy,
modified), ....... 497
195. Diagram of Lumbar Plexus, . . . 513
196. The Lumbar Plexus (semi-diagrammatic), . . .514
197. Mesial section through the Pelvis, . . . .518
198. The Peritoneum of the Pelvic Cavity, .... 520
199. Diagram of the Pelvic Wall and Pelvic Floor, . . 522
200. Dissection to expose the Pelvic Fascia from the outer side.
(Arthur ThOxMson), ..... 523
201. Dissection of the Pelvic Fascia. (Arthur Thomson), . 524
202. Inner aspect of the lateral and hinder walls of the Pelvis, . 527
203. Vertical section through the Bladder, Prostate, and Pubic
Arch to show the arrangement of the Pelvic Fascia :
schematic, ....... 529
204. Diagram of the Pelvic Fascia as seen in a mesial section of the
Pelvis, ....... 530
205. Diagram of the Pelvic Fascia, ..... 532
206. Dissection of the Rectum from the front, . . . 534
207. Oblique, section from above downwards and forwards through
the Pelvis, ....... 536
208. Dissection of the Rectum from behind. (Birmingham), . 537
209. Coronal section through the whole length of the Anal Canal.
(Symington), ...... 539
210. Bladder hardened in situ viewed from the right side. (A. F.
Dixon), ....... 540
211. Diagram of the Under Surface of the Empty Bladder. (After
Dixon), ....... 5^0
212. Bladder hardened in situ viewed from the right side. (A. F.
Dixon), ....... 541
213. Mesial section through the Pelvis of an Adult Male, . . 543
214. Mesial section through a Male Pelvis, . . . 544
215. Mesial section through the Pelvis of a newly-born full-time
Male Infant, ...... 545
xviii LIST OF ILLUSTRATIONS
KIG. l'AGE
2 1 6. Basal aspect of Bladder, Seminal Vesicles, and Prostate
hardened by formalin injection, , 548
217. Horizontal section through the Bladder and Rectum, . . 549
218. Dissection of the two Levatores Ani, .... 556
219. The Sacral and Sacro-coccygeal Plexuses, as seen from behind, 558
220. The lower part of the Rectum and the Anal Canal opened
up. (Charles B. Ball), ..... 565
221. Interior of Bladder in region of the Urethral Orifice. (A. F.
Dixon), ....... 566
222. Oblique section from above downwards and forwards through
the Pelvis, . . . . . .568
223. Diagram of the Bladder, Urethra, and Penis. (Delepine), . 570
224. Mesial section through terminal part of the Penis, . . 573
225. Transverse section through the anterior part of the body of the
Penis, ....... 575
226. Posterior view of the Pelvic Ligaments and of the Hip-joint, . 577
227. Coronal section through the Pelvis, .... 579
228. Mesial section through Female Pelvis, . . . 582
229. Horizontal section through the Urethra, Vagina, and Anal
Canal, a short distance above their terminations. (Henle), 583
230. The Uterus, with the Broad Ligament stretching out from
either side of it. (From Gegenbaur), . . . 584
231. Mesial section through the Female Pelvis. (Dixon and
Birmingham), ...... 585
232. Mesial section through a Female Pelvis, . . . 588
233. Diagram of the Vulva, Vagina, and the Uterus, with its Append-
ages. (Symington), ..... 592
234. The Uterus, with the Broad Ligament stretching out from
either side of it. (From Gegenbaur), . . . 593
235. Left Side Wall of Female Pelvis to show position of the Ovary, 595
236. The Ampulla and Fimbriated End of the Fallopian Tube ;
the Ovary ; and the Parovarium. (From Gegenbaur,
modified), ....... 596
237. Interior of the Uterus. (Luschka), .... 601
MANUAL OF ANATOMY.
.MANUAL
OF
PRACTICAL ANATOMY
THE UPPER LIMB.
'THE dissector of the upper limb begins work on the third
■*• day after the subject has been placed in the dissecting-
room. He will then find the subject stretched out at full
length upon its face, with the pelvis and chest supported by
blocks (Fig. i); and while the body remains in this position
he must examine those structures which connect the limb to
the posterior aspect of the trunk.
Surface Anatomy. — Before proceeding to the actual dis-
section of any region, the student should make it an invariable
practice to familiarise himself with the bony prominences
within its area. It is by using these as landmarks that the
surgeon is enabled to establish the position of the component
parts of the body in the living subject.
In the middle line of the back there is little difficulty in
recognising the tips of the spinous processes of the vertebrae.
These follow each other in consecutive order, and it will be
observed, when the finger is passed over them, that they do
not, in every case, occupy the mesial plane ; some of them
may be deflected, in a slight degree, to one side or the other.
The spines of the vertebrae are the only parts of the vertebral
column which come to the surface ; they alone yield direct
information, by touch, to the surgeon as to the condition
of the spine. At the lower end of the neck, the spine of
the seventh cervical vertebra {vertebra prominens) makes a
VOL. I 1
2 THE UPPER LIMB
visible projection ; and the spines of the first two dorsal
vertebras are likewise very prominent. As a rule, the most
evident of the three is that of the first dorsal vertebra. At
a lower level, in subjects of good muscular development, a
mesial furrow is produced by the prominence of the erector
spinas muscle on each side, and the spines of the vertebras
may then be felt at the bottom of the groove. The furrow
attains its greatest depth in the upper part of the lumbar
region, and it fades away below at the level of the spine of
the third sacral vertebra. The finger should next be passed
along the crest of the ilium as it pursues its sigmoid course
forwards and outwards. The highest point of the iliac crest
corresponds in level with the spine of the fourth lumbar
vertebra, and the posterior superior spine of the ilium can be
easily detected, seeing that its position is indicated by a small
but distinct depression or dimple on a level with the second
sacral spine.
The scapula is for the most part thickly covered by
muscles ; but, in spite of this, its general outline can be
made out. The scapula covers a considerable area of the
upper portion of the chest-wall on its posterior aspect. With
the hand by the side its superior angle lies over the second
intercostal space, the root of its spine is placed opposite the
spine of the third dorsal vertebra, whilst its inferior angle
reaches down as far as the seventh, or even the eighth, rib.
The scapula is very mobile, and moves to a greater or less
degree with every movement of the limb. The spine and
acromion process of the scapula are subcutaneous throughout.
Below the scapula the lower five ribs can be felt, and the
tip of the last rib can be made out to reach a point about
two inches above the iliac crest.
DISSECTION OF THE BACK.
In this dissection the following nre the parts which
require to be examined : —
i. The cutaneous vessels and nerves of the back.
2. The trapezius muscle.
3. The latissimus dorsi muscle.
4. The rhomboid muscles and their nerve of supply.
5. The levator anguli scapula? muscle.
DISSECTION OF THE BACK 3
6. The spinal accessory nerve and the nerves from the cervical
plexus which supply the trapezius.
7. The transversalis colli artery and its two terminal branches (viz.
the posterior scapular and the superficial cervical).
8. The posterior belly of the omohyoid muscle.
9. The suprascapular artery and nerve.
This dissection must be completed in two days, in order that
the dissector of the head and neck may be enabled to con-
tinue the deeper dissection of the back. The first day's work
should comprise — (1) the reflection of the skin ; (2) the
dissection of the cutaneous nerves and vessels; and (3) the
cleaning of the latissimus dorsi and trapezius muscles. The
remainder of the dissection can be undertaken on the second
da v.
Fir.. 1.
Reflection of the Skin. — The following incisions arc necessary: — 1.
From the tip of the coccyx upwards, along the middle line of the body
to the spine of the seventh cervical vertebra. 2. From the upper end of
the foregoing mesial incision transversely outwards, to the tip of the
acromion process of the scapula. 3. From the lower extremity of the
mesial incision in a curved direction outwards and forwards, along the
crest of the ilium, to within two inches of the anterior superior iliac spine.
4. An oblique incision from the spine of the first lumbar vertebra, up-
wards and outwards, to the hinder border of the acromion process. The
two large flaps which are now mapped out upon the back must be care-
fully raised from the subjacent fatty tissue. Reflect the upper triangular
flap first, and then deal in the same way with the lower flap.
Superficial Fascia. — The fatty layer which is now exposed
is termed the superficial fascia. It constitutes the cushion
upon which the skin rests, rounds off the angularities of
the body, and varies in thickness according to the obesity of
the subject. In subjects which have been allowed to lie for
some time on the back it is usually more or less infiltrated
4 THE UPPER LIMB
with fluid which has gradually gravitated into its loose
meshes. The superficial fascia constitutes the bed in which
the cutaneous vessels and nerves ramify before they enter
the skin ; and it is separated from the muscles by a tough,
but thin, layer of fibrous tissue, devoid of fat, which forms
another investment for the body. This aponeurotic mem-
brane receives the name of the deep fascia ; it can be readily
demonstrated by making an incision in the superficial fascia,
and raising a small portion of it.
Dissection. — In searching for a cutaneous nerve, cut boldly down
through the superficial fascia in the direction in which the nerve runs,
until the plane at which the superficial and deep fasciae blend is reached.
It is here that the main trunks are to be found ; and in a well-injected
subject the cutaneous arteries constitute the best guides. A more rapid
way of finding the cutaneous nerves in this region is to reflect in one layer
both the superficial and the deep fascia outwards from the vertebral spines.
The nerves are seen piercing the muscles. This plan, however, should
only be adopted by the senior student.
Cutaneous Vessels and Nerves. — The cutaneous nerves of
the back are derived from the posterior primary divisions of
the spinal nerves. As the latter pass backwards, they divide
into external and internal branches. Both of these supply
twigs to the muscles amongst which they lie ; but one or other
also contains some sensory fibres which come to the surface,
in the shape of a cutaneous nerve, to supply the skin.
In the dorsal region the upper six or seven cutaneous
nerves are the terminations of the internal branches of the
posterior primary divisions of the spinal nerves. They become
superficial close to the vertebral spines, and are to be sought
for near the mesial plane. It is not uncommon to find one
or more of them piercing the trapezius one or two inches
external to the line of emergence of the others. The branch
which comes from the second dorsal nerve is the largest of
the series; and it may be traced outwards, towards the shoulder,
beyond the spine of the scapula. The lower five or six
cutaneous nerves in the dorsal region are the terminal twigs of
the external branches of the posterior primary divisions of
the spinal nerves ; and, consequently, they must be looked
for at a short distance from the middle line of the back.
They reach the surface by piercing the latissimus dorsi muscle
on a line with the angles of the ribs and outer margin of
the erector spinas muscle. In every case the cutaneous
branches derived from the dorsal nerves turn outwards in
DISSECTION OF THE BACK 5
the superficial fascia, and may be traced for a varying distance
in this direction.
It is important to note that the area of skin supplied by
Great occipital nerve
Third occipital nerve
Sterno-mastoid
Small occipital nerve
Complexus ,
Splenitis
Cervical nerves to trapezius
Spinal accessory- nerve
Superficial cervical artery
I.evator anguli scapula
Posterior scapu lar artei
and nerve to rhomboid
— Rhomboideus mine
Trapezius
(reflected)
1 Rhomboideus
major
Teres major
^erratus magnus
Latissimus dorsi
External branches of
posterior divisions of
lumbar nerves
| Serratus posticus inferior
Latissimus dorsi
■ External oblique muscle
■ Trigonum Petiti
H- Gluteus mediu-
ms Gluteus maximus
Fig. 2. — Dissection of the Superficial Muscles and Nerves cf the Back.
each of these cutaneous nerves is placed at a lower level
than the origin of the posterior primary division from which
it arises.
In the lumbar region three cutaneous nerves reach the
surface by piercing the lumbar aponeurosis at the outer
margin of the erector spinae, a short distance above the
1— 1 a
6 THE UPPER LIMB
ilium They are the terminal twigs of the external branches
of the posterior primary divisions of the three upper lumbar
spinal nerves ; and they differ from those above, inasmuch
as they turn downwards over the crest of the ilium to supply
the skin of the gluteal region (Fig. 2).
The cutaneous arteries which accompany these nerves come
from the dorsal branches of the intercostal and lumbar
irtenes.
Muscles connecting the limb to the dorsal aspect of the
trunk.— These are five in number, and are arranged in two
strata Two form the superficial stratum, viz., the trapezius
and the latissimus dorsi. Both are broad, flat muscles which
rover the greater part of the dorsal aspect of the trunk, from
the occiput above to the ilium below. The trapezius lies
over the back of the neck and the chest. The latissimus
dorsi is placed lower down. The deeper stratum of muscles,
composed of the levator anguli scapulae and the two rhomboid
muscles, is placed under cover of the trapezius.
Dissection.- -The trapezius muscle should now be cleaned. This muscle
belongs only in part to the dissector of the upper limb. The portion oi it
which lies above the prominent spine of the seventh cervical vertebra is the
property of the dissector of the head and neck, and must be dissected by
him Let the two dissectors work in conjunction with each other ; and
when the entire muscle is exposed, let each give the other an opportunity
of studying it in its entirety. . ■*•«„„„
In cleaning the trapezius the limb must be placed in such a position as
will render the fibres of the muscle tense. If the dissection is being made
on the right side, the arm must be placed close to the trunk, and drawn
downwards, whilst the scapula is dragged well forwards over the end of
the block which supports the chest. A transverse cut is now to be made
through the superficial and deep fascia, from the seventh cervical spine
outwards. This incision will be found to coincide with the direction of
the fibres of the muscle at this level. From this point gradually work
downwards, raising both fascia? in a continuous layer from the surface ot
the muscle.' The knife must always be carried in the direction of the
muscular fibres : and care must be taken to leave none of the thin filmy,
deep fascia behind. If this rule be attended to, it will be found that, as
the dissection progresses, the knife is not, as at first, carried transversely,
but obliquely, in accordance with the alteration in the direction of the
fibres of the lower portion of the muscle. When this stage is reached, a
change in the position- of the arm is required in order that the lower
oblique fibres may be stretched to the full extent. The scapula must still
be kept as far forwards as possible ; but the limb must be carried upwards,
and placed parallel to the neck. In the case of the left trapezius, the
student must make the incision through the fascia, along the lower margin
of the muscle, and work upwards to the level of the seventh cervical
vertebra. In the first instance the limb must be extended, and, at a later
stage, placed by the side, as the transverse fibres of the muscle are reached.
In removing the fascia from the trapezius, and indeed throughout the
DISSECTION OF THE BACK 7
whole dissection of the back, the cutaneous nerves must be carefully pre-
served, in order that the dissector of the head and neck may have an
opportunity of establishing their continuity with the trunks from which
they arise.
Trapezius. — The trapezius is a flat, triangular muscle,
which lies in its entire extent immediately subjacent to the
deep fascia. It has a very wide origin, which extends along
the mesial plane, from the occiput above to the level of the
last dorsal vertebra below. It arises from — (1) the inner third
or less of the superior curved line of the occipital bone and
the external occipital protuberance ; (2) the ligamentum
nuchae and the spine of the seventh cervical vertebra ; (3) the
tips of the spines of all the dorsal vertebrae, as well as the
Fig. 3. — Upper Surface of the Right Clavicle.
supraspinous ligaments which bridge across the intervals
between them (Fig. 2).
In the lower cervical and upper dorsal regions the tendinous fibres by
which the muscle arises lengthen out so as to form a flat tendon, which,
taken in conjunction with the corresponding aponeurosis of the opposite
side, exhibits an oval outline.
As the fibres of the trapezius pass outwards, they converge
to gain an insertion into the two bones of the shoulder-girdle.
The occipital and upper cervical fibres incline downwards, and
turning forwards over the shoulder, are inserted into the outer
third of the posterior border of the clavicle (Fig. 3) ; the lower
cervical and upper dorsal fibres pass more or less transversely
outwards, to gain an insertion into the inner border of the
acromion process and the upper margin of the spine of the
scapula ; while the lower dorsal fibres are directed upwards
and, at the base of the scapula, end in a flat, triangular
tendon, which plays over the smooth surface at the root of
the scapular spine, and is inserted into a rough tubercle on
1—16
8 THE UPPER LIMB
the spine of the scapula immediately beyond this (Fig. 21,
p. 49). To facilitate the movement of the tendon upon the
bone a small synovial bursa intervenes between them.
The trapezius is supplied by the spinal accessory nerve and
by twigs from the third and. fourth cervical nerves.
Dissection. — The latissimus dorsi is now to be dissected. It is a difficult
muscle to clean, not only on account of the varying direction of its fibres,
but also because its upper part is generally very thin, and its upper border
ill-defined. Near the spines of the vertebra? it is overlapped in its upper
part by the trapezius, but in its greater extent it is subcutaneous. Both
layers of fascia should be raised at the same time from its surface, and its
fibres may be stretched by raising the arm and folding it under the neck.
The origin of the latissimus dorsi in the lumbar region is effected through
the medium of the superficial lamina of the lumbar fascia, a dense tendinous
aponeurosis, which covers the erector spinas in the loins (Fig. 2). Clean
this structure thoroughly. The attachment of the muscle to the crest of
the ilium, and its slips of origin from the lower ribs, must be carefully
defined ; at the same time, the posterior and lower part of the external
oblique muscle of the abdomen should be cleaned, so that its relation to
the latissimus dorsi may be studied. As the latissimus dorsi sweeps over
the inferior angle of the scapula it receives an accession of fibres from that
bone. This fleshy slip may be brought into view when the muscle is
cleaned by relieving the tension of the muscular fibres, and then turning
the upper margin of the muscle outwards. The slip in question is apt to
be mistaken for a piece of the teres major muscle upon which it lies.
Latissimus Dorsi. — The latissimus dorsi is a wide, flat
muscle, which covers the back from the level of the sixth
dorsal vertebra down to the crest of the ilium (Fig. 2, p. 5).
It arises — (1) from the tips of the spinous processes of the
lower six dorsal vertebrae and the supraspinous ligaments in
connection with them; (2) from the superficial lamella of
the lumbar fascia (Fig. 4) ; (3) by a thin tendinous origin
from a small extent of the outer lip of the crest of the ilium
in front of the lumbar fascia (Fig. 2, p. 5) ; (4) by three or
four digitations from the lower three or four ribs ; and (5)
by a fleshy slip from the dorsal aspect of the inferior angle
of the scapula (Fig. 21, p. 49). By means of its origin from
the posterior lamella of lumbar fascia, it receives an indirect
attachment to the spines of the lumbar and upper sacral
vertebrae, and also to the posterior part of the crest of the
ilium. The costal slips of origin interdigitate with the lower
digitations of the external oblique muscle of the abdominal
wall.
The fibres of the latissimus dorsi converge rapidly as they
approach the lower part of the scapula. The highest fibres
pass almost horizontally outwards towards this point ; the
DISSECTION OF THE BACK 9
lowest fibres ascend almost vertically ; whilst the intermediate
fibres show varying degrees of obliquity. As a result of this
convergence of fibres, the muscle is greatly reduced in width ;
and it sweeps over the inferior angle of the scapula in the
form of a thick, fleshy band which winds round the lower
margin of the teres major muscle, to gain insertion, by
means of a narrow, flat tendon, into the bottom of the
bicipital groove of the humerus (Fig. 30, p. 72). This insertion
cannot be studied at present, but will be seen later on. With
Fig. 4. — Diagram of the Lumbar Fascia.
I.
Serratus posticus inferior.
6.
Fascia transversals.
2.
Latissimus dorsi.
7-
Erector spinas.
.:>-
Transversalis abdominis.
8.
Quadratus lumborum
4-
Obliquus iijternus.
9-
Psoas.
5-
Obliquus externus.
the teres major muscle the latissimus dorsi forms the posterior
fold of the axilla. At first placed on the dorsal aspect of
the teres major, the latissimus dorsi is folded round its lower
border, and finally at its insertion comes to lie in front of
it. To this peculiar relationship of the two muscles is due
the full, rounded appearance of the posterior axillary fold.
The latissimus dorsi is supplied by the middle or long
subscapular nerve.
Two Intermuscular Spaces. — A triangular space mapped
io THE UPPER LIMB
out by the lower border of the trapezius, the upper border of
the latissimus dorsi, and the base of the scapula, will now be
noticed (Fig. 2, p. 5). Within these limits a small portion of
the rhomboideus major will be seen, and also a varying amount
of the chest wall — a part corresponding to the sixth intercostal
space and the borders of the ribs which bound it above and
below. It is well to note that this is the only part of the
thoracic parietes on the posterior aspect of the trunk which
is uncovered by muscles. Further, between the last rib and
the crest of the ilium the anterior border of the latissimus
dorsi will generally be observed to overlap the posterior
border of the external oblique muscle of the abdominal wall.
Sometimes, however, a narrow triangular interval exists
between the two muscles, in which is seen a small part of
the internal oblique muscle. This space is termed the
trigonum Petiti (Fig. 2, p. 5).
Reflection of the Trapezius. — On the second day the dissector should
begin by reflecting the trapezius. This should be done, if possible, in
conjunction with the dissector of the head and neck. Divide the muscle
about two inches from the spines of the vertebrae, and throw it outwards
towards its insertion. The trapezius is very thin at its origin, and the
greatest care must therefore be taken not to injure the subjacent rhomboid
muscles. The small bursa between the tendon of insertion of the lower
part of the trapezius and the triangular root of the spine of the scapula must
not be overlooked.
Nerves and Vessels of Supply to the Trapezius. — A dis-
section of the deep surface of the reflected muscle will reveal
the following structures : —
a. The spinal accessory nerve.
b. Two or three nerves from the cervical plexus.
c. The superficial cervical artery.
These constitute the nervous and vascular supply of the
trapezius (Fig. 2, p. 5).
The nerves have already been displayed by the dissector of
the head and neck, as they cross the posterior triangle of the
neck. The branches from the cervical plexus come from the
third and fourth cervical nerves. On the deep surface of the
trapezius they join with branches of the spinal accessory to
form the subtrapezial plexus, from which twigs proceed into the
substance of the muscle. The terminal twig of the spinal
accessory nerve can be traced nearly to the lower margin of
the trapezius.
DISSECTION OF THE BACK u
The superficial cervical artery which accompanies the spinal
accessory nerve must be followed to the anterior border of
the trapezius, where it will be seen to spring from the trans-
versal is colli artery.
Dissection. — The posterior belly of the omo-hyoid and the suprascapular
artery and nerve can now be displayed by dissecting towards the upper
margin of the scapula, and removing carefully the loose fatty tissue in this
locality. The dissector of the head and neck must take part in this dis-
section, and it is well not to expose these structures for more than an inch
from the upper margin of the scapula.
Omo-hyoid. — Suprascapular Artery and Nerve. — The
slender posterior belly of the omo-hyoid muscle will be seen to
arise from the upper border of the scapula immediately behind
the suprascapular notch. It also derives fibres from the liga-
ment which bridges across this notch. It is supplied by a
twig from the ansa hypoglossi. The suprascapular artery will be
noticed to enter the supraspinous fossa of the scapula by passing
over the suprascapular ligament, whilst the suprascapular nerve
proceeds into the fossa under cover of that ligament.
Dissection. — Draw the scapula well over the edge of the block which
supports the chest of the subject. The two rhomboid muscles are thus
rendered tense, and the cleaning of the fleshy fasciculi greatly facilitated.
The nerve to the rhomboids should be secured at this stage, so that it may
be preserved from injury in the further dissection of the region. It can
best be detected by dissecting in the interval between the rhomboideus
minor and the levator anguli scapulae about one inch to the inner side of
the superior angle of the scapula (Fig. 2, p. 5). It is accompanied by the
posterior scapular artery, and it will afterwards be traced upon the deep
surface of the rhomboid muscles when they are reflected.
Rhomboid Muscles. — The two rhomboid muscles constitute
a thin quadrangular sheet of muscular fibres, which proceeds
from the spinous processes of the vertebrae to the base of the
scapula.
The 7'homboideus minor is a narrow, ribbon-like fleshy band
which runs parallel to the upper border of the greater rhomboid.
It springs from the lower part of the ligamentum nuchae, the
spine of the seventh cervical vertebra, and frequently also from
the spine of the first dorsal vertebra. It is inserted into the
base of the scapula opposite the triangular surface at the root
of its spine (Fig. 21, p. 49). It is entirely covered by the
trapezius.
The rhomboideus major arises from the upper four or five
dorsal spines, and the corresponding part of the supraspinous
ligament. Its fibres run obliquely downwards and outwards,
12 THE UPPER LIMB
and end in a tendinous cord, which receives insertion into the
base of the scapula close to the inferior angle. From this
point, up to the commencement of the spine, the tendinous
cord is firmly bound to the base of the scapula by areolar
tissue (Fig. 21, p. 49). The greater part of the rhomboideus
major is covered by the trapezius ; only a small portion near
the inferior angle of the scapula lies immediately subjacent to
the deep fascia.
Levator Anguli Scapulae (musculus levator scapulae). —
This is an elongated muscle which arises by four more or less
tendinous slips from the posterior tubercles of the transverse
processes of the upper four cervical vertebrae, and passes
downwards and backwards to be inserted into the base of the
scapula from the superior angle to the spine. It is supplied
by branches from the third and fourth cervical nerves.
Dissection. — In cleaning the levator anguli scapulae muscle care must
be taken of the nerves which pass to it from the cervical plexus, and also
of the nerve to the rhomboids and the posterior scapular artery which lie
under cover of it near the base of the scapula. The dissector of the head
and neck has an interest in the levator anguli scapulae, and when it has
been studied by both dissectors it should be divided midway between its
origin and insertion, and the lower portion turned outwards. The nerve
to the rhomboids has already been secured in the interval between the
rhomboideus minor and the levator anguli scapulae, and it has still further
been exposed by the reflection of the latter muscle. It may now be dis-
played in its whole length, together with the posterior scapular artery,
which it accompanies, by reflecting the rhomboid muscles. These should
be detached from the ligamentum nuchae and the vertebral spines, and
thrown outwards towards the base of the scapula. In doing this care
must be taken of the serratus posticus superior, a thin muscle which lies
subjacent, and is apt to be injured.
Nerve to the Rhomboids (nervus dorsalis scapulae). — This
nerve is a long slender twig which arises in the neck from the
fifth cervical nerve, and usually in common with the upper root
of the nerve of Bell. It pierces the scalenus medius, and then
proceeds downwards under cover of the levator anguli scapulae
to the deep surface of the rhomboid muscles to which it is
distributed. The nerve to the rhomboids likewise supplies
one or two twigs to the levator anguli scapulae.
The nerve to the rhomboids sometimes pierces the levator
anguli scapulae in two or more branches, which unite in a
plexiform manner.
Posterior Scapular Artery. — The posterior scapular artery
is a branch of the transversalis colli, and takes origin in the
lower part of the neck close to the outer margin of the
DISSECTION OF THE BACK 13
levator anguli scapulae. x\t first it proceeds backwards under
cover of this muscle, but soon changing its direction it
runs downwards along the base or vertebral border of the
scapula under cover of the rhomboid muscles (Fig. 2, p. 5).
It gives numerous branches to both ventral and dorsal
aspects of the scapula, and its terminal twigs may enter
the latissimus dorsi. One large branch usually passes
backwards in the interval between the rhomboid muscles, or
through the greater rhomboid, to reach the trapezius muscle ;
and another branch, the supraspinal, is given to the supra-
spinatus muscle, and the structures superficial to it.
Reflection of Latissimus Dorsi. — Divide the muscle by carrying the
knife from its upper margin, about three inches from the vertebral spines,
obliquely downwards to a point a little way behind its digitation from
the last rib. In raising the inner portion of the muscle care must be
taken of the subjacent serratus posticus inferior. The attachment of the
latissimus dorsi to the crest of the ilium and to the lumbar aponeurosis
can now be verified. The outer part of the muscle is next to be thrown
forwards, so that the three costal digitations may be seen from their deep
aspect, and also for the purpose of displaying the termination of the sub-
scapular artery and the long subscapular nerve. These are found upon
the deep surface of the muscle at the inferior angle of the scapula.
Lastly, replace the outer portion of the latissimus dorsi muscle, and fix
it in position by a stitch or two around one or more of the ribs. This is
done with the view of preserving the posterior fold of the axilla.
The dissector of the arm now stops work for two days.
He has completed the dissection of all the dorsal structures
which are allotted to him, and he has nothing further to do
until the body is turned.
PECTORAL REGION AND AXILLARY SPACE.
On resuming work the dissector will find the body lying
upon its back. The chest is raised to a convenient height
by means of blocks. A long board is placed under the
shoulders for the purpose of supporting the arms when
they are abducted from the sides (Fig. 5).
In dissecting the axilla and chest it will be found advantageous if the
dissectors of the arm and of the head and neck arrange to work at different
hours. The dissector of the head and neck at this stage is engaged at the
posterior triangle of the neck, and this dissection cannot be well done
unless the arm be placed close to the side and the shoulder depressed.
For the dissection of the axilla the arm should be stretched out at right
angles to the chest. A compromise between these two positions always
results in discomfort to both dissectors.
I4 THE UPPER LIMB
Four Days are allowed for the dissection of the pectoral
redon and the axillary space. The arm must then be
removed, so as to allow the dissector of the thorax to
commence the dissection of the thoracic wall. Ihe follow-
ing Table may be found useful in regulating the amount ol
work which should be undertaken each day : —
First Day.-(a) Surface Anatomy ; (b) reflection of skin ; (r) cutaneous
vessels and nerve of the chest, both on its anterior and lateral aspects ;
KS of the pectoralis major muscle; (e) reflection of the axillary
fascia TT/) cleaningof that part of the serratus magnus muscle which lies
below the fourth rib. „,, . •
Second Day. -Dissection of the axillary space from below This in-
cludes the boundaries and contents of the space, in so far as they can oe
wot at without the reflection of any muscle. „frtVOi;c
Third Day.-(a) Reflection of the clavicular portion of the pectora is
maior ; (*) the costo-coracoid membrane and the structures piercing it ; W
removal of the membrane; (d) the dissection of the upper part of the
axilla • (6-) reflection of the sternal part of the pectoralis major.
Fourth Day.-(«) Reflection of pectoralis minor muscle ; (5) genera
revision of the space and study of the axillary vessels and nerves ;(c)
removal of the middle third of clavicle ; (d) subclavius muscle ; (e) brachial
plexus ; (/) nerve of Bell and serratus magnus muscle ; (g) separation of
limb from the trunk.
Surface Anatomy.— The entire length of the clavicle
can be felt under the skin, and as the student follows its
curves with his finger he can recognise the origins of the
pectoralis major and deltoid muscles along its anterior
border In a few instances these muscles may present an
unbroken line of origin from the sternal to the acromial
end of the bone, but in the vast majority of cases a
triangular interval is left between them. This is marked
on the surface by a shallow depression, termed the infra-
clavicular fossa, and it is rendered all the more apparent
by the prominence of the shoulder on its outer side, and
the sharp backward curvature of the clavicle immediately
above it If the finger be placed in this fossa, and pressed
backwards and outwards, it will rest upon the inner side of
the coracoid process of the scapula. The articulations of
the clavicle should also be examined. Little or no promi-
nence is formed by the outer end of the clavicle— its upper
surface passes continuously on to the upper surface of the
acromion process of the scapula. By moving the limb,
however, the joint can easily be detected. In strong con-
trast to this is the sterno-clavicular joint, where the inner
end of the clavicle can be felt as a marked projection,
PECTORAL REGION 15
although this is masked to the eye by the sternal part of
the sterno-mastoid muscle. The suprasternal notch on the
upper border of the manubrium sterni between the clavicles
should next be felt, and then the finger can be carried
downwards in the middle line and in front of the sternum.
A prominent ridge, crossing the bone transversely at the level
of the second costal cartilages, indicates the junction between
the meso-sternum or gladiolus and the manubrium sterni.
The portion of the sternum uncovered by the two greater
pectoral muscles is narrow above, but it widens out below, and
suddenly, at the lower end of the meso-sternum, the finger
sinks into a depression between the cartilages of the seventh
mm ...l^:iv-^7TnTT_"" H
Fig. 5.
pair of ribs, and rests upon the ensiform cartilage. This is
termed the infrasternal fossa, or pit of the stomach. The
costal arches below the first arc easily recognised, but the
first rib lies deeply under the clavicle, and can only be felt in
front at its junction with the manubrium sterni. The arm
should now be abducted (i.e., carried outwards from the
trunk), when the hollow of the armpit will be brought into
view, as well as the two rounded folds which bound it in
front and behind. The anterior fold of the axilla is formed
by the lower border of the pectoral is major, and to a small
extent also by the lower border of the pectoralis minor. The
posterior fold, which is formed by the latissimus dorsi as it
winds round the teres major muscle, is carried downwards
to a lower level than the anterior fold. This, as we shall
see later on, is an important point in connection with the
1 6 THE UPPER LIMB
anatomy of the axilla. If the finger be pushed upwards into
the axilla, the globular head of the humerus can be felt when
the arm is rotated. One other point demands the attention
of the student before the dissection is commenced, and that
is, the position of the nipple. As a rule it lies superficial
to the interspace between the fourth and fifth ribs, and it is
situated rather more than four inches from the middle line.
Reflection of Skin. — Incisions— (i) Along the middle line of the body
from the upper margin of the manubrium sterni to the tip of the ensiform
cartilage ; (2) from the lower end of this vertical incision transversely
outwards round the side of the body ; (3) from the upper extremity of the
primary incision outwards along the clavicle to the extremity of the
acromion process ; (4) from the lower end of the vertical and mesial
incision {i.e., tip of the ensiform cartilage) obliquely upwards and out-
wards along the anterior fold of the axilla to the point at which this joins
the upper arm. This last incision may, with advantage, be carried
vertically down the arm for two and a half or three inches.
Two triangular flaps of skin are marked out by these incisions, and
these are now to be raised from the fatty superficial fascia. It is well to
encircle the areola and nipple with the knife, and leave the skin covering
them undisturbed.
Superficial Fascia. — The superficial fascia presents here,
as elsewhere, the usual characters, but, as a rule, the fat is not
so plentiful. As it descends over the clavicle to the upper
part of the chest and summit of the shoulder, it will be seen
in most cases to present a faintly ruddy striated appearance.
Should this not at first be apparent, the removal of some
of the superficial fat will render it visible. This appearance
is due to the presence of a number of sparse scattered
muscular fasciculi which stream down over the clavicle, to
obtain origin in the superficial fascia over the pectoralis
major and deltoid muscles. In the neck they form a thin,
cutaneous, fleshy stratum, called the platysma myoides. The
superficial fascia in this region is also peculiar in so far as it
has developed within it the mammary gland. It should now
be dissected with the view of exposing the gland as well as
the cutaneous vessels and nerves which make it their bed
before entering the skin.
Cutaneous Nerves and Arteries. — There are three distinct
groups of cutaneous nerves for the supply of the skin on the
anterior and lateral aspects of the chest. These are —
1. The descending cutaneous — from the cervical plexus.
2. The anterior cutaneous, \ c tl • . . 1
~, , . , ' from the intercostal nerves.
3. The lateral cutaneous, J
PECTORAL REGION 17
The descending cutaneous nerves arise in the neck from
the third and fourth cervical nerves, and, spreading out as
they descend, they cross the clavicle under cover of the
platysma myoides. They are classified according to their
position into the sternal, the clavicular, and the acromial
branches. The sternal branch is the smallest of the series,
and crosses the inner part of the clavicle to end in
the skin immediately below. The clavicular branches pass
over the middle of the clavicle, and extend downwards for
some distance, in the superficial fascia over the pectoralis
major. The acromial branch crosses the outer third of the
clavicle, and will be afterwards followed to the skin of the
shoulder.
These nerves can readily be found by cutting down upon the clavicle
through the platysma muscle, and in the direction of its fibres.
The anterior cutaneous nerves are the minute terminal twigs
of the intercostal trunks, and they become superficial by
piercing the pectoralis major muscle and deep fascia close to
the margin of the sternum. One will be found in each inter-
costal interval, and they are accompanied by the perforating
branches of the internal mammary artery, which (when injected)
serve as the best guides to the nerves. They give slender
twigs to the skin over the sternum, and larger branches
which are directed outwards, and may be traced as far as
the anterior fold of the axilla.
The lateral cutaneous nerves, much larger than the pre-
ceding, arise from the intercostal nerves, and appear on the
side of the chest, along a line situated a little behind the
anterior fold of the axilla. They pierce the chest wall in the
interspaces between the ribs, and divide into anterior and
posterior branches under cover of the serratus magnus muscle.
These will be found appearing between the digitations of
the serratus magnus. The anterior branches come out, as a
rule, about an inch in front of the corresponding posterior
branches, and then proceed forwards over the lower border of
the pectoralis major muscle. From the lower members of
this series some minute twigs are given off, which enter the
superficial surface of the digitations of the external oblique
muscle of the abdomen. The posterior branches run back-
wards to the dorsal aspect of the trunk over the anterior
border of the latissimus dorsi muscle.
vol. 1. — 2
1 8 THE UPPER LIMB
It is advisable not to attempt to secure the two highest lateral cutaneous
nerves (i.e. , those issuing from the second and third intercostal spaces) in
the meantime. They are best dissected along with the other contents of
the axillary space.
Dissection. — If the subject be a female the dissector should endeavour
to make out the connections, and also something of the structure, of the
mammary gland. The small area of skin which has been left over the
areola should be raised towards the summit of the nipple, and bristles
may be introduced through the orifices of the ducts which may be seen on
the extremity of the nipple. Further, by removing the fat which surrounds
Teres major
Latissimus dorsi
Pectoralis major
Lobules of the gland
Ampullae of ducts
Serratus magnus
Fibrous trabeculae of the gland
Fig. 6. — Dissection of the Mammary Gland.
the organ, the true glandular tissue will be rendered more 'apparent,
although it is only in favourable circumstances that the milk-ducts in the
nipple and their ampullae in the region of the areola can be isolated and
rendered apparent.
Mammary Gland (mamma). — In the female the mammary
gland forms a rounded prominence on the front, and also
to some extent on the lateral aspect, of the chest. It lies
in the superficial fascia, and its smooth contour is largely
due to the invasion of its substance by the fatty tissue of this
layer.
A little below its mid-point, and at a level which usually
corresponds to the fourth intercostal space, the mamma is
PECTORAL REGION
19
surmounted by a conical elevation termed the nipple or
mammilla (papilla mammae). This stands in the middle of a
circular patch of coloured integument which is called the
areola mamma. Within the nipple, and also subjacent to the
areola, there is no fat. A curious change of colour occurs in
this region during the second month of pregnancy. Of a
Processes radiating
from the corpus 1
Pectoralis major
Ductus lactiferi
.j^>
Fat lobule
Fig. 7. — Section through a Mammary Gland prepared by method
recommended by Mr. Harold Stiles.
delicate pink colour in the virgin, the skin of the nipple and
areola becomes brown from the deposition of pigment at this
time, and it never again resumes its original appearance.
The mammary gland extends in a horizontal direction
from the side of the sternum to very nearly the mid-axillary
line on the side of the chest ; and in a vertical direction from
the second costal arch above to the sixth costal cartilage
below. About two-thirds of the gland are placed upon the
1 — 2 a
2o THE UPPER LIMB
pectoralis major muscle, whilst the remaining part, which
corresponds to its inferior and outer third, extends beyond
the anterior fold of the axilla, and lies upon the serratus
magnus muscle. From the part which lies in relation to the
lower border of the pectoralis major a prolongation extends
upwards into the axilla, and reaches as high as the third rib.
The mammary gland is not isolated by a capsule from the
surrounding fatty tissue of the superficial fascia. Pervading
it, and supporting the true glandular substance, there are
strands or trabecular of connective tissue which constitute its
stroma or framework, and which are directly continuous with
the fibrous tissue which supports the fat of the superficial
fascia. The stroma and gland-substance together constitute
a conical mass termed the corpus mamma. Processes pro-
ject out from both the surface and margins of the corpus
mammae, and into the hollows between these projections
is deposited the fat which gives the smooth contour to the
organ. Many of the processes which extend from the surface
are attached to the deep surface of the skin, and give rise
to the so-called ligaments of Cooper.
The gland substance is arranged in lobes and lobules, and
the ducts issuing from these converge towards the areola.
Some fifteen or more lactiferous ducts (ductus lactiferi) pass
in towards the base of the nipple. Subjacent to the areola
these ducts expand into fusiform dilatations termed ampulla
or sinus lactiferi, and then contracting they traverse the sub-
stance of the nipple, upon the summit of which they open.
In a well -injected subject, twigs from the intercostal
arteries, and also from the perforati?ig branches of the
internal mammary, may be traced into the mammary gland,
and another vessel, called the external mammary artery, may
be seen winding round the edge of the greater pectoral
muscle, or piercing its lower fibres to reach the gland.
By means of lymphatic vessels the mammary gland is
brought into connection with the sternal glands, and also
more directly with the axillary glands. The latter connection
is one of much importance to the surgeon in cases where it
is necessary to remove the organ for malignant disease.
In the male the mamma (mamma virilis) is extremely
rudimentary. The nipple is small and pointed, and the
areola is surrounded by sparse hairs.
Deep Fascia. — The deep fascia of the pectoral region is a
PECTORAL REGION
2 I
thin membrane which closely invests the pectoralis major. It
is attached superiorly to the clavicle, and is firmly connected
in the middle line to the front of the sternum. Below, it is con-
tinuous with the deep fascia covering the abdominal muscles,
and, at the lower border of the great pectoral muscle, it is
continuous with the axillary fascia. At the infraclavicular
fossa a process from its deep surface dips in between the
Cephalic vein
ictoralis major
Deltoid muscle
Chain of glands related to the axillary
Serratus tnagnus
Pectoralis minor
Pectoral glands
tissimus dorsi
Pectoralis major
Lymphatic vessels
to sternal glands
Fig. 8. — The Lymphatic Glands and Vessels of the Axilla and Mammary
Gland. (From Poirier and Cnneo — modified. I
deltoid and pectoralis major muscles to join the costo-
coracoid membrane, whilst, beyond this, the aponeurosis
becomes continuous with the fascia covering the deltoid
muscle. The axillary fascia and the costo-coracoid mem-
brane will be described later on.
Dissection. — The pectoralis major muscle must now be cleaned, and its
division into sternal and clavicular parts clearly made out. The muscular
fibres are rendered tense by abducting the arm from the side. On the
right side the dissector begins at the lower border of the muscle, whilst on
the left side he commences at the upper border. Clean also the anterior
margin of the deltoid. In the interval between it and the portion of the
1—2/-
22 THE UPPER LIMB
pectoralis major which arises from the clavicle, the cephalic vein and,
subjacent to this, the humeral thoracic artery will be discovered.
Infraclavicular Lymphatic Glands. — In the interval
between the adjacent margins of the pectoralis major and
deltoid muscles immediately below the clavicle are placed
one, or it may be two, lymphatic glands which receive the
lymphatic vessels which accompany the cephalic vein.
These vessels convey the lymph from the outer side of the
arm and the shoulder.
Pectoralis Major. — This powerful muscle extends from the
anterior aspect of the chest to the humerus. It is divided by
a deep fissure into a clavicular and a costo-sternal portion.
This fissure penetrates through the entire thickness of the
muscle, the clavicular and costo-sternal portions being thus
distinct, except close to their insertion. The clavicular portion
arises by short tendinous and muscular fibres from an im-
pression on the inner half of the anterior surface of the
clavicle (Fig. 3, p. 7). The costo-sternal portion takes origin
by fleshy fibres from the anterior surface of the sternum,
from the aponeurosis of the external oblique muscle, and
occasionally from the sixth rib near its cartilage. Under
cover of this more superficial origin, and partially independent
of it, a variable number of muscular slips spring from the
cartilages of the upper six ribs.
The pectoralis major is inserted by a flattened bilaminar
tendon into the outer lip of the bicipital groove of the
humerus (pectoral ridge), and the fibres of the muscle undergo
a re-arrangement as they converge upon this tendon. The
greater part of the clavicular portion joins the anterior
lamina of the common tendon ; some of the innermost
clavicular fibres, however, are inserted directly into the
humerus below the tendon, whilst a fewr gain attachment
to the deep fascia of the arm, and become adherent to the
adjacent part of the deltoid.
The fibres of the costo-sternal portion of the muscle take
different directions as they proceed to join both laminae of
the tendon of insertion ; thus the upper fibres descend
slightly, the intermediate fibres pass horizontally outwards,
whilst the lower fibres ascend, and, at the same time, gain
the deep surface of the rest of the muscle. A smooth, full,
and rounded lower border is in this way formed which con-
stitutes the anterior fold of the axilla. The precise manner
AXILLARY SPACE 23
in which it is attached to the humerus will be more fully
studied at a later 'stage of the dissection.
The pectoralis major is supplied by the internal and ex-
ternal anterior thoracic nerves.
Axilla. — The axillary space may be denned as being the
hollow or recess between the upper part of the side of the
chest and the upper part of the arm. When the limb is
abducted from the trunk, and the areolo-fatty tissue which
occupies the armpit is removed, the space presents a pyra-
midal form. The apex, or narrow part of the space, placed
immediately to the inner side of the coracoid process, is
directed upwards towards the root of the neck, whilst the
wider part or base looks downwards. But the space is not
absolutely pyramidal in form, for the inner wall formed by
the chest is of greater extent than the outer wall formed by
the arm. It follows from this, therefore, that the anterior
and posterior walls converge as they proceed outwards.
Before engaging in the dissection of the space, it is necessary
that the student should have some knowledge of its bound-
aries, and the manner in which its contents are disposed
in relation to these.
Boundaries of the Axilla. — The anterior wall is formed by
the two pectoral muscles and the costo-coracoid membrane.
The pectoralis major constitutes the superficial stratum, and
is spread out over the entire extent of the anterior wall.
The pectoralis minor, which lies subjacent to the greater
pectoral muscle, is only in relation to about one-third of the
anterior boundary, whilst the interval or gap between this
muscle and the clavicle is filled up by the costo-coracoid
membrane. The lower border of this wall of the axilla
constitutes its anterior fold, as already explained. This is
formed by the lower margin of the pectoralis major, with a
small part of the lower border of the pectoralis minor, which
comes into view near the side of the chest.
The posterior wall of the axilla is somewhat longer than
the anterior wall. It is formed from above downwards by
the subscapularis muscle, the tendon of the latissimus dorsi,
and the teres major muscle. The subscapularis, lying upon
the venter of the scapula, takes by far the largest share
in the formation of this wall. The narrow tendon of the
latissimus dorsi lies in front of the teres major, so that only
the lower border of the latter muscle is seen below it.
1—2 c
24
THE UPPER LIMB
The posterior fold of the axilla is formed by the lower border
of this wall.
The inner wall is constituted by the upper four or five
ribs with the intervening intercostal muscles ; it is clothed by
the corresponding digitations of the serratus magnus muscle.
The outer wall is formed by the humerus and the conjoined
origin of the coraco-brachialis and short head of the biceps.
The apex of the space corresponds with the narrow com-
munication between the axilla and the root of the neck. It
is a triangular interval (which can readily be investigated by
the finger when the space is dissected) bounded by the
clavicle, first rib, and upper margin of the scapula, and
through it pass from the neck the great axillary vessels and
i. Upper end of humerus
2. Scapula.
3. Rib.
4. Pectoralis major.
5. Serratus magnus.
6. Subscapularis.
7. Axillary vein.
8. Axillary artery.
0. Long head of biceps.
10. Conjoined origin of
short head of biceps
and coraco-brachi-
alis.
11. 12. 13. Brachial nerves.
Fig. 9. — Diagram of section through the Axilla of the Left Side.
brachial nerves. The wide vaulted base of the armpit is
closed by the axillary fascia.
Contents of the Axilla. — The axillary artery and vein,
with the great brachial nerves, constitute the most important
contents of the armpit. Except at the summit of the space,
they lie closely applied to the outer wall, and follow it in all
the movements of the upper arm. Of the branches which
spring from the axillary artery, two (viz.. the thoracic axis
and the long thoracic) are related to the anterior wall ; two
(viz., the posterior circumflex and subscapular) to the posterior
wall ; one, the superior thoracic, to the inner wall : and one,
the anterior circumflex, to the outer wall.
The thoracic axis artery arises high up in the space, and at
once proceeds forwards through the costo-coracoid membrane.
The long thoracic artery runs inwards along the lower border of
the pectoralis minor. The posterior circumflex artery arises
from the posterior aspect of the main trunk, and at once
AXILLARY SPACE 25
leaves the space by passing backwards through the posterior
wall in the interval between the subscapulars and the teres
major muscles. The subscapular artery runs inwards along the
lower border of the subscapularis muscle. The anterior circum-
flex^ a small vessel, proceeds outwards upon the humerus,
under cover of the coraco-brachialis and short head of the
biceps. The superior thoracic artery, also a small vessel,
ramifies upon the first intercostal space high up in the axilla.
In making an opening into the axilla from below, for the purpose of
allowing a collection of pus to escape, or for any other purpose, it is
necessary to bear these relations in mind. The outer wall, where the
great axillary vessels are, must be most carefully avoided ; so also must be
the anterior and posterior walls, where there would be a risk of injuring
the long thoracic and subscapular arteries. The inner wall, however, is,
comparatively speaking, free from danger, as the small thoracica suprema
is placed high up in the space. Therefore enter the knife with the sides of
the blade towards the anterior and posterior walls of the space, and with
the back of the blade towards the outer wall and axillary vessels. The
knife may then be carried inwards towards the chest.
But there are various nerves in relation to the walls of
the axilla. Entering the deep surface of the anterior wall
are the two anterior thoracic nerves for the supply of the two
pectoral muscles. Upon the posterior wall are the three
subscapular nerves, which supply the three muscles which con-
stitute this boundary. Running downwards upon the inner
wall is the nerve of Bell, or posterior thoracic nerve, while
piercing it are the intercosto-humeral and upper lateral cutaneous
nerves.
In addition to the contents already enumerated, numerous
lymphatic glands are lodged in the fat of the axillary space.
Axillary Fascia. — This is a dense felted membrane which
stretches across the base of the armpit. It is continuous in
front with the deep fascia covering the pectoralis major,
behind with the sheaths of the latissimus dorsi and teres
major muscles, and internally with the deep fascia over the
serratus magnus. It is drawn upwards towards the hollow of
the axilla. This is chiefly due to the connection of its deep
surface with the sheath of the pectoralis minor, but also to its
attachment to the areolar tissue which fills the space. In a
well-injected subject a small artery, from the lower part of the
axillary trunk, may be observed ramifying upon the fascia.
Dissection. — Begin the dissection of the axilla from below by carefully
separating the deep fascia from the lower edge of the pectoralis major
26 THE UPPER LIMB
muscle, so as to expose and clean the anterior fold of the axilla. Then
grasp the edge of the fascia with the hand and pull it backwards, teasing
out with the point of the knife the areolar tissue, which holds it in place.
By this means the axillary fascia is reflected in one piece, and the upper
lateral cutaneous nerves are put on the stretch, and can be followed out.
There are three steps in the dissection of the axilla : (i) the display of
those contents which can be reached from below after the removal of the
axillary fascia ; (2) the reflection of the clavicular part of the pectoralis
major and the removal of the costo-coracoid membrane which brings into
view the structures in the upper part of the space ; and (3) the reflection of
the sternal portion of the pectoralis major which opens up the space from
the front.
The senior student is recommended to adopt an alternative plan.
Leaving the axillary fascia for the time being in its place, detach the
sternal part of the pectoralis major from its origin and throw it outwards.
The greater extent of the axilla is thus at once opened up from the front,
and the various contents can be displayed with great ease. In opera-
tions for the removal of the mammary gland the surgeon employs this
method of gaining access to the axillary space for the purpose of removing
the lymphatic glands. It is well, therefore, that the student should have
the opportunity of seeing the axillary contents as they are brought into
view in this manner. The dissection is completed by the reflection of the
clavicular part of the pectoralis major, and later of the pectoralis minor.
Lateral Cutaneous Branches of the Second and Third
Intercostal Nerves. — As a rule, the first intercostal nerve
does not give off a lateral cutaneous nerve. That which
springs from the second intercostal nerve is the largest of
the series, and differs from the others in not dividing into an
anterior and posterior branch. It is termed the intercosto-
humeral ?ierve, on account of its being distributed to the skin
on the inner and back aspect of the upper part of the arm.
To reach this destination it crosses the axilla and pierces the
deep fascia. But before doing so it establishes communica-
tions and forms a plexiform arrangement in the axilla with
the nerve of Wrisberg (the lesser internal cutaneous nerve)
and the lateral cutaneous branch of the third intercostal nerve.
This plexus may be joined by another twig, which is occa-
sionally present, viz., the minute lateral cutaneous branch of
the first intercostal nerve.
The lateral-cutaneous branch of the third intercostal nerve
divides into an anterior and posterior part, and these are dis
tributed in the ordinary way. From the posterior branch
twigs are given to the skin of the axilla, and the terminal
twigs are distributed to the integument on the upper part of
the inner aspect of the arm.
Lymphatic Glands. — In the subsequent dissection of the
axilla the lymphatic glands must be removed as they are
AXILLARY SPACE
27
brought into view. Many of them are very minute, and are
likely to escape the attention of the dissector. The position
which they occupy in the space should be carefully noted.
They are disposed in three groups — (a) a chain of six or
more glands lying close to the axillary vessels, which extends
from the lower border of the pectoralis major up into the
apex of the axilla and receives the lymphatic vessels ascending
„ . ,. . Deltoid muscle Chain of elands in relation to axillary vessels
Cephalic vein ^
ctoralis major \
\
Serratus maernus
atissimus dorsi
Pectoralis major
Pectoralis minor
Pectoral glands
Lymphatic vessels
co sternal glands
FlG. 10. — The Lymphatic Glands and Vessels of the Axilla and Mammary
Gland. (From Poirier and Cuneo — modified.)
from the limb ; (b) a group of pectoral glands placed along
the lower border of the pectoralis minor and on the inner
wall of the thorax in the angle between the pectoral muscles
and the serratus magnus, which are joined by the lymphatics
from the outer two-thirds of the mammary gland and the
front of the chest ; (c) a group of subscapular glands, situated
along the lower border of the subscapularis muscle on the
posterior wall of the axilla, and into which the lymphatics of
the back pour their contents.
28 THE UPPER LIMB
A central group of glands has been recently described (Leaf). These
either lie superficial to the axillary fascia or in a pocket formed by it.
Sometimes they are placed upon the deep aspect of the axillary fascia, in
which case they are associated with the subscapular group.
Dissection. — The loose areolar tissue and fat must now be cautiously
removed from the hollow of the armpit. Begin by dissecting out the sub-
scapular artery and the long subscapular nerve. The guide to their
position is the lower margin of the subscapularis muscle. In relation to
the lower border of the pectoralis minor muscle the long thoracic artery
will be found. A vertical incision along the inner wall, a short distance
anterior to the point where this joins the posterior wall, will display the
external respiratory nerve, or the nerve of Bell, upon the axillary surface
of the serratus magnus. These structures being secured, the dissector may
proceed with his work more boldly, as the remaining contents of the space
are not so liable to injury. The axillary artery and vein and the great
brachial nerves may next be exposed. Note the close manner in which
they cling to the outer wall of the axilla in the various movements of the
limb, and then isolate them thoroughly by removing their areolar sheaths,
and establish their individual identity. In dissecting these structures care
must be taken to secure the small internal cutaneous branch of the
mzisculo-spiral nerve. This nerve is generally given off within the axilla
in common with a muscular branch to the long head of the triceps, and it
crosses the latissimus dorsi and teres major tendons on a deeper plane than
the branches of the intercosto-humeral nerve. The lowest subscapular
nerve must now be looked for upon the surface of the subscapularis muscle.
Axillary Artery (arteria axillaris). — It is the third part of
the axillary artery which is now exposed, and the vein will be
seen to lie upon its inner side, and also partly in front of it.
It is important to note the position of the large nerves, with
reference to the artery, before they are much disturbed by
the dissection. The ulnar ?ierve lies in direct contact with
its inner side. The nerve of Wrisberg (the lesser internal
cutaneous nerve) is also internal to the artery, but is separated
from it by the axillary vein, to which it is closely applied.
The ifiternal cutaneous nerve, and the inner head of the median,
lie in front of the artery ; the ?nnsculo-spiral and circumflex
nerves are directly behind it ; while the i?iedian and musculo-
cutaneous nerves are placed upon its outer side. The latter
nerve soon leaves the artery, by deviating outwards and
entering the substance of the coraco-brachialis muscle. Its
branch of supply to that muscle should be secured at this
stage.
In this part of its course the axillary artery gives off
three branches — the subscapular, which has already been
found ; the posterior circumflex, which arises from its posterior
aspect ; and the anterior circumflex, a small vessel which runs
AXILLARY SPACE
29
outwards under cover of the coraco-brachialis, and is apt to
be injured in cleaning the nerves.
Dissection. — The axillary space must now be dissected from the front.
This is done by reflecting the clavicular part of the pectoralis major. The
sternal portion of the muscle is not to be disturbed at present. Divide
the clavicular part close to its origin from the clavicle, and throw it down-
wards and outwards. This must be done with care, because some twigs
from the external anterior thoracic nerve, and also some of the pectoral
thoracic branches of the thoracic axis artery, enter its deep surface. These
must be cleaned and preserved.
Outer cord of brachial plexus
Posterior cord
Inner cord
Musculo-cutaneous nerve
Outer head of median
nner head of median
Internal cutaneous
Lesser internal cutaneous
Intercosto-humeral
-Median
Ulnar.
Ar Musculo-spiral
Fig. 11. — Diagram to show relation of Brachial Nerves to Axillary Vessels.
Costo-Coracoid Membrane. — A space or gap between the
clavicle and pectoralis minor is now exposed. This gap,
however, is closed by the costo-coracoid membrane, the
connections of which must be studied.
When the costo-coracoid membrane is traced outwards
it is found to be attached to the coracoid process ; and when
followed inwards its attachment to the first rib becomes
evident. Above, it constitutes the sheath of the subclavius
muscle by splitting into an anterior and a posterior layer.
These, passing upwards, enclose the muscle, and are attached,
the one to the anterior border of the clavicle, and the other
to the posterior border of the bone.
3°
THE UPPER LIMB
With the view of demonstrating these two layers, divide the anterior
lamina transversely close to the clavicle, and throwing it downwards, pass
the handle of the scalpel upwards behind the muscle. The posterior
attachment can in this manner be verified, and at the same time the nerve
to the subclavius will be seen sinking into the deep surface of the muscle.
The density of the membrane diminishes almost immedi-
ately below the subclavius, and this so abruptly that a crescentic
band is formed, which, on account of its being thicker and
stronger than the rest of the membrane, is sometimes called
the costo-coracoid, or bicornuate ligament. The lower
connections of the membrane are somewhat indefinite, and
Clavicle
Subclavius
Thoracic axis
Axillary sheath
.Axillary fascia
Fig. 12. — Diagram of the Costo-coracoid Membrane.
difficult to establish with precision. In a good subject,
however, it will be seen to join the sheath of the axillary
vessels, and also to give a process of fascia to the sheath of
the pectoralis minor.
Four structures pierce the costo-coracoid membrane, and
these should now be cleaned. They are: — (i) the thoracic
axis artery, breaking up into pectoral, clavicular, acromial,
and humeral branches; (2) the thoracic axis vein; (3) the
cephalic vein ; (4) and lastly, the external anterior thoracic
nerve.
V Dissection. — The costo-coracoid membrane should be removed, and
the axillary space entered from above. With a little dissection the
contents of the upper part of the space may be exposed. These are the
axillary artery, with the axillary vein on its inner side, and partly
AXILLARY SPACE 31
overlapping it. To the outer side, and to some extent above the vessels,
are placed the great brachial nerves. All these important structures are
enveloped in a loose, funnel-shaped sheath, which is prolonged into the
axilla from the deep cervical fascia. Crossing behind the artery, and
therefore lying very deeply, is the external respiratory fierce, or nerve of
Bell. A small branch, called the superior thoracic, takes origin from this
part of the axillary artery. Lastly, the cephalic and thoracic axis veins
must be traced to their junction with the axillary vein.
The sternal part of the pectoralis major muscle may now be divided
about its middle, and the two portions thrown outwards and inwards.
Several nerves will be observed entering its deep surface, and these must
be preserved. They come from the external and internal anterior thoracic
nerves. One or more from the latter pierce the pectoralis minor, and are
now seen emerging from its anterior surface. The pectoralis minor must
be cleaned and its attachments defined.
Pectoralis Minor. — This is a fan -shaped muscle, which
extends from the thoracic wall to the scapula. It arises by
three flat, tendinous slips from the third, fourth, and fifth
ribs, close to their cartilages. Between the ribs these slips
are prolonged into the anterior intercostal aponeuroses.
From this origin the fibres proceed outwards and upwards,
and converge upon a stout tendon, which is inserted into
the front part of the inner border and upper surface of the
coracoid process (Fig. 17, p. 41). The pectoralis minor is
supplied by the internal anterior thoracic nerve.
Dissection. — The axillary vessels and the brachial nerves can now be
cleaned throughout their entire extent, but the pectoralis minor muscle
should not be reflected until the relations of these important structures
have been thoroughly studied.
Axillary Artery (arteria axillaris). — The axillary artery is
a portion of the great arterial trunk which carries blood for
the supply of the upper limb. It begins above at the outer
border of the first rib, where it is continuous with the sub-
clavian artery, and it ends below at the lower border of the
teres major muscle, where it becomes continuous with the
brachial artery. Its course through the axilla varies with the
position of the limb. When the arm is abducted from the
trunk (as it is when the axilla is being dissected), a straight
line, drawn from the centre of the clavicle to a point below
the anterior fold of the axilla, and immediately to the inner
side of the slight prominence caused by the coraco-brachialis
muscle, will, with tolerable accuracy, indicate the course pur-
sued by the vessel.
The relations of the axillary artery vary very much as
it traverses the armpit : and with the view of obtaining a
32 THE UPPER LIMB
greater precision of description, anatomists are in the habit
of arbitrarily dividing the vessel into three parts. The first
part extends from the outer border of the first rib to the
upper border of the pectoralis minor ; the second part lies
under cover of that muscle ; the third part extends from
the lower border of the pectoralis minor to the lower
border of the teres major.
The first part of the axillary artery lies very deeply. It is
covered by the skin, superficial fascia, deep fascia, clavicular
part of the pectoralis major, and the costo-coracoid membrane.
But, even when these are removed, the vessel is not completely
exposed, because it is enveloped, along with the axillary vein
and great nerves, by a funnel-shaped sheath, which is prolonged
upon them from the deep cervical fascia. Further, it is
crossed by the cephalic and thoracic axis veins, and the loop
of communication between the two anterior thoracic nerves
likewise lies in front of it. Posteriorly, this part of the vessel
is supported by the first intercostal space and the first
digitation of the serratus magnus muscle, and the nerve of
Bell crosses behind it. To its i?mer side, and somewhat
overlapping it, is the axillary vein, whilst above and to its
outer side are the large brachial nerve-trunks.
The secotid part of the axillary artery is placed behind
the two pectoral muscles, and has the three cords of the
brachial plexus disposed around it. Thus the inner cord
lies upon its inner side, the outer cord upon its outer side,
and the posterior cord behind it. The axillary vein is still
upon its inner side, but is separated from the artery by the
inner nerve-cord. Strictly speaking, it is not in apposition
with any muscle posteriorly, being separated from the sub-
scapulars muscle by areolo-fatty tissue.
The third and longest part of the axillary artery is superficial
in its lower half. This is due to the fact that the posterior
wall of the axilla extends lower down than the anterior wall.
Whilst, therefore, it is covered in its upper half by the
pectoralis major, below this it is only covered by the
integument and fascia?. Behind, it rests, from above down-
wards, on the subscapularis, the tendon of the latissimus
dorsi, and the lower margin of the teres major. To its outer
side, is the coraco-brachialis muscle ; whilst to its inner side, is
the axillary vein. The brachial nerve- cords have now given
place to their large branches, and these are disposed around
AXILLARY SPACE 33
the vessel. The precise positions which they occupy in the
undisturbed condition of parts, and when the arm is abducted
from the side, have been already described on page 28.
The Branches of the Axillary Artery have been observed
at different stages of the dissection. They may now be more
fully examined. They are : —
Alar thoracic, . ^|
Subscapular, . . I from the third
o . ., • ) from the first
Superior thoracic, -
Thoracic axis, . ) from the second I Anterior circumflex, part.
Long thoracic, . J part. | Posterior circumflex, J
Superior Thoracic Artery (arteria thoracica suprema).—
This is a small branch which springs from the axillary at the
lower border of the subclavius muscle and ramifies upon the
upper part of the inner wall of the axilla. It supplies twigs
to the serratus magnus muscle, the intercostal muscles, and
the pectoral muscles.
Thoracic Axis (arteria thoracicoacromialis). — The thoracic
axis is a short wide trunk, which is frequently described as
arising from the first part of the axillary artery. As a rule,
however, it takes origin under cover of the pectoralis minor,
and winds round the upper border of that muscle. Piercing
the costo-coracoid membrane, it immediately divides into
numerous branches, which diverge widely from each other.
These receive different names, and are arranged as follows : —
(a) The clavicular bra?ich (ramus clavicularis), a small twig, runs
upwards to the clavicle and then turns inwards along that
bone between the clavicular part of the pectoralis major and
the costo-coracoid membrane, (b) The pecto?-al branches (rami
pectorales), of larger size, proceed downwards between the
two pectoral muscles, give branches to both, and anastomose
with the long thoracic and intercostal arteries. (c) The
acromial branch (ramus acromialis) runs outwards upon the
tendon of the pectoralis minor and the coracoid process.
Some of its twigs supply the deltoid, whilst others pierce it
to reach the upper surface of the acromion process. It
anastomoses with the suprascapular and posterior circumflex
arteries, (d) The humeral branch (ramus deltoideus), as a
rule, takes origin from a trunk common to it and the
preceding artery, and it runs downwards in the intermuscular
interval between the pectoralis major and the deltoid. To
both of these muscles it gives twigs.
vol. 1 — 3
34
THE UPPER LIMB
Long Thoracic Artery (arteria thoracica lateralis). — This
vessel takes the lower border of the pectoralis minor as its
guide, and proceeds downwards and inwards to the side of the
chest. It gives branches to the pectoral muscles, the serratus
magnus, and the mammary gland, and anastomoses with twigs
from the intercostal arteries. It gives off, as a rule, an external
mammary branch, which winds round or pierces the lower
border of the pectoralis major to reach the mammary gland.
Alar Thoracic. — This small artery supplies the fat and
Acromio-
. . . thoracic artery
Anterior circum- .
flex artery \
Thoracic axis artery
OR: SUPREMA.
Dorsalis scapulae artery Posterior circumflex artery
Fig. 13. — The Axillary Artery and its Branches.
lymphatic glands in the axilla, and rarely arises as a separate
branch from the axillary artery. Its place is usually taken by
twigs from the subscapular and long thoracic arteries.
Subscapular Artery (arteria subscapularis). — The sub-
scapular artery is the largest branch of the axillary artery, and
it arises opposite the lower border of the subscapularis muscle.
Following this, it runs downwards and backwards, in company
with the long subscapular nerve, to the inferior angle of the
scapula, where its terminal twigs anastomose with the posterior
scapular artery. Not far from its origin the subscapular artery
AXILLARY SPACE
35
gives off a large branch, the dorsalis scapula (arteria circum-
flexa scapulas), which winds round the axillary border of the
scapula, in close contact with the bone, to reach its dorsal
aspect. Numerous smaller twigs are given to the neighbour-
ing muscles, viz., the subscapularis, latissimus dorsi, and
serratus magnus.
Circumflex Arteries. — These are two in number, and as a
rule they both arise from the axillary at the same level, a
short distance below the origin of the subscapular artery.
The posterior circumflex (arteria circumflexa humeri posterior)
is much the larger of the two. Only a small portion of it
can be seen at the present stage. It springs from the
posterior aspect of the axillary, and at once proceeds back-
wards with the circumflex nerve close to the inner and under
Trapezoid
ligament
M A _J o
I u s
Fig. 14. — Under Surface of the Clavicle with the Attachments of the
Muscles mapped out.
aspect of the head of the humerus, and in the interval
between the subscapularis and teres major muscles. The
small anterior circumflex artery (arteria circumflexa humeri
anterior) takes origin from the outer aspect of the axillary, and
runs outwards in front of the surgical neck of the humerus,
under cover of the coraco-brachialis and short head of the
biceps. Reaching the bicipital groove, it divides into two
branches. Of these one is directed upwards with the long
head of the biceps to the shoulder-joint ; the other continues
onwards to the under surface of the deltoid, and finally
anastomoses with some of the terminal twigs of the posterior
circumflex artery.
Axillary Vein (vena axillaris). — This venous trunk is the
continuation upwards of the basilic vein of the upper arm.
Beginning at the lower border of the teres major, it becomes
the subclavian vein at the outer margin of the first rib. At
the lower margin of the subscapularis it receives the two
36 THE UPPER LIMB
vence comites of the brachial artery, and above the level of the
pectoralis minor it is joined by the cephalic vein. Its other
tributaries correspond, more or less closely, to the branches
of the axillary artery.
Subclavius Muscle. — -The subclavius muscle may now be
cleaned and its attachments defined. It is a small muscle,
placed below the clavicle, and it is enclosed in a stout sheath
derived from the costo-coracoid membrane. It takes origin
by a short rounded tendon, from the upper surface of the
first costal arch at the junction of the rib with its cartilage,
and the small fleshy belly is inserted into the shallow groove
on the under surface of the clavicle. Its nerve of supply
comes from the fifth and sixth cervical nerves, and has been
previously noticed, p. 30.
Dissection. — The middle third of the clavicle should now be removed,
and the subclavius muscle reflected, in order that a connected view of the
structures which pass from the side of the neck into the axilla may be
obtained. The dissector of the head and neck should also take part in
this dissection. At the same time the pectoralis minor may be divided
about an inch and a half from its insertion, and the two parts thrown
inwards and outwards. In doing this care must be taken of the internal
anterior thoracic nerve which pierces its deep surface. When the continuity
of the axillary and subclavian vessels has been satisfactorily displayed they
may be ligatured in two places at the level of the clavicle and then divided
between the ligatures. By throwing the axillary vessels downwards the
examination of the brachial nerves will be greatly facilitated. The dense
connective tissue which surrounds these large nerves should be completely
removed and the arrangement of the brachial plexus studied.
Brachial Plexus (plexus brachialis). — This important plexus
is formed by the anterior primary divisions of the four lower
cervical nerves and the greater part of the large anterior
primary division of the first dorsal nerve. Above, the plexus
is further reinforced by a small twig of communication which
passes from the fourth to the fifth cervical nerve, whilst below,
a similar connecting twig not infrequently passes upwards, in
front of the neck of the second rib, from the second to the
first dorsal nerve. The manner in which these great nerves
unite to form the plexus is very constant. The fifth and sixth
nerves unite to form an upper trunk ; the seventh remains single
and proceeds downwards as a middle trunk ; whilst the eighth
cervical and first dorsal nerves join close to the intervertebral
foramina to constitute a third or lower trunk. A short
distance above the clavicle each of these three trunks splits
into an anterior and a posterior division. Raise the three
AXILLARY SPACE
37
anterior divisions on the handle of the knife, and it will be
seen that all the three posterior divisions unite to form the
posterior cord of the plexus, and, further, that the innermost
c.v
c.vi
C.VII
C.VII!
D.ll
Fig. 15. — Diagram of the Brachial Plexus. The posterior cord of the plexus
with the three posterior divisions which form it and the branches which
proceed from it are tinted yellow.
S1, S'2, S:^ — The three subscapular nerves. Cir.— Circumflex nerve.
of these divisions is much smaller than the other two. Of
the three anterior divisions the two outer join to constitute
the outer cord, whilst the innermost is carried downwards by
itself as the inner cord of the plexus. From the three cords
1— 3 a
38 THE UPPER LIMB
of the plexus are given off the branches which supply the
upper limb.
From the above description it will be seen that the plexus,
from changes which are effected in the arrangement of its
fibres, may be divided into four stages : —
First Stage, . . Five separate. nerves (viz., four lower cervical and
first dorsal).
Second Stage, . . Three nerve-trunks (viz. , an upper, middle, and
lower).
Third Stage, . . Three anterior divisions and three posterior
divisions.
Fourth Stage, . Three nerve-cords (viz., an outer, inner, and a
posterior).
The first two of these stages are generally observed in the
lower part of the posterior triangle of the neck, and the last
two behind the clavicle and in the upper part of the axilla.
It must be understood, however, that the points at which
division and union of the different parts of the plexus take
place are subject to much variation.
Infraclavicular Branches of the Brachial Plexus. — The
branches of the brachial plexus are usually classified into two
groups, viz., those which arise above the level of the clavicle,
and those which take origin within the axilla. The latter
group of nerves must now be studied by the dissector of the
upper limb. They consist of a number of short branches,
which end in the muscles forming the anterior and posterior
walls of the axilla, and a series of large terminal branches,
which are prolonged downwards into the upper arm. They
are : —
1. Axillary branches —
From outer cord :
External anterior thoracic (from C. v., C. VI., C. VII.).
From inner cord :
Internal anterior thoracic (from C. Vlll., D. I.).
From posterior cord :
Three subscapular nerves (from C. v., C. VI., C. VII., C.
VIII.).
2. Brachial branches —
From outer cord :
Musculo-cutaneous (from C. v., C. VI.).
Outer head of median (from C. VI., C. vii.).
From inner cord :
Inner head of median (from C. vin. , D. I.).
Ulnar (from C. VIII., D. I.).
AXILLARY SPACE 39
Internal cutaneous (from C. VIII.-, D. I.).
Lesser internal cutaneous (from D. I.).
From posterior cord :
Circumflex (from C. v., C. vi.).
Musculo-spiral (from C. v., C. VI., C. VII., C. villa-
in the above table the different spinal nerves from which the fibres
which compose the several nerves are derived are indicated.
Anterior Thoracic Nerves (nervi thoracici anteriores). —
These are the branches of supply to the pectoral muscles, or,
in other words, to the two muscles which form the anterior wall
of the axilla. The external anterior thoracic nerve springs
from the outer cord of the plexus, pierces the costo-coracoid
membrane above the level of the pectoralis minor, and breaks
up into branches which sink into the deep surface of the
pectoralis major. The internal anterior thoracic nerve, some-
what smaller, arises from the inner cord of the plexus, and
passing forwards between the axillary artery and vein enters
the deep surface of the pectoralis minor. After supplying
this muscle its terminal filaments emerge from its anterior
surface, and sink into the pectoralis major. The pectoralis
major is therefore supplied by both anterior thoracic nerves ;
the pectoralis minor by the internal anterior thoracic nerve
alone. Close to their origin the two nerves are usually united
by an arch or loop, thrown over the front of the axillary
artery ; in other cases they may join in a plexiform manner,
before proceeding to their destinations.
Subscapular Nerves (nervi subscapulares). — The three sub-
scapular nerves spring from the posterior cord of the plexus,
and supply the three muscles which form the posterior wall
of the axilla. The upper subscapular nerve is placed high up
in the axilla. It is very short, sometimes double, and it sinks
into the substance of the subscapularis muscle. The long or
middle subscapular tierve accompanies the subscapular artery
and supplies the latissimus dorsi. The loiver subscapular nerve
gives twigs to the lower border of the subscapularis muscle,
and ends in the teres major.
Dissection. — The cords of the brachial plexus may now be divided.
Begin with the inner and outer cords, because when these are thrown
downwards a better view of the posterior cord and the three subscapular
nerves will be obtained. When the posterior cord is cut the arm should
be forcibly dragged away from the trunk, so as to put the serratus magnus
on the stretch.
Posterior Thoracic Nerve (nervus thoracicus longus). —
The external respiratory ?ierve of Bell, or the posterior
r— 3 6
4o
THE UPPER LIMB
thoracic nerve, as it passes downwards upon the outer surface
of the serratus magnus, may now be studied in its whole
length. It is the nerve of supply to the serratus magnus,
and it arises in the root of the neck by three roots from
the brachial plexus. The upper two roots (one from the
Scalenus medius
111! Scalenus amicus
Upper part of serratus
magnus
jk Middle portion of
''S5s^^tt3 serratus magnus
**^<i\ Lower portion of
]\j^ serratus magnus
Fig. 16. — Serratus magnus muscle and origin of the external oblique muscle ;
the scapula is drawn away from the side of the chest.
fifth cervical and the other from the sixth cervical nerve)
pierce the scalenus medius, and uniting into one stem give
off branches to the upper part of the serratus magnus. The
third root takes origin from the seventh cervical nerve, and
passes in front of the scalenus medius. It runs downwards
for a considerable distance on the surface of the serratus
magnus, before it unites with the other part of the nerve.
AXILLARY SPACE 4,
The entire nerve, thus formed, can be followed to the lower
part of the serratus, giving twigs to each of its digitations.
Serratus Magnus Muscle.— The serratus magnus arises
Coraco-brachialis
and short
head of
biceps Pectoralis minor
Omo-hyoid
Long head
of triceps
Fig. 17. — Ventral aspect of the Scapula with the Attachments
of Muscles mapped out.
by fleshy digitations from the upper eight or nine ribs, about
midway between their angles and cartilages. These slips are
arranged on the chest wall, so as to present a gentle curve
convex forwards. The lower three or four interdigitate with
the external oblique muscle of the abdomen. The serratus
42 THE UPPER LIMB
magnus is inserted into the entire length of the vertebral
border of the scapula. The muscle falls naturally into three
parts, (a) The upper part, composed of the large first digita-
tion alone, arises from the first and second ribs, and from a
tendinous arch between them. The fibres converge, to be
inserted into a somewhat triangular surface on the ventral
aspect of the superior angle of the scapula, (b) The middle
part consists of two digitations which take origin from the
second and third ribs. The upper slip is very broad, and
springs from the lower border of the second rib. The fibres
diverge to form a thin muscular sheet, which is inserted into
the anterior lip of the vertebral border of the scapula, between
the insertions of the upper and lower portions. (c) The lower
part is formed by the remaining digitations of the muscle.
These converge to form a thick mass, which is inserted into
a rough surface upon the ventral aspect of the inferior angle
of the scapula. The deep surface of the serratus magnus
is in contact with the chest wall.
Removal of the Arm from the Body. — Draw the arm forcibly from the
side and cut through the serratus magnus, the omo-hyoid, and the latissimus
dorsi muscles, also the suprascapular artery and nerve, and the vessels and
nerves in relation to the trapezius and rhomboids, if these have not been
previously divided. The arm will then be found to be free, and it may be
carried to one of the tables which are reserved for the dissection of separate
parts.
SHOULDER— SCAPULAR REGION.
In the dissection of this region the following parts must be
studied : —
i. Cutaneous nerves of the shoulder.
2. Deep fascia.
3. Deltoid muscle.
4. Sub-acromial bursa.
5. Anterior and posterior circumflex vessels.
6. Circumflex nerve.
7. Dorsalis scapulae artery.
8. Subscapulars muscle.
9. Supraspinatus, infraspinatus, teres minor, and teres major
muscles.
10. Bursoe in connection with the shoulder -joint.
11. Suprascapular nerve and artery.
12. Acromio-clavicular joint, and the coraco-acromial arch.
SHOULDER— SCAPULAR REGION 43
Muscles inserted into the Clavicle and Scapula. — The insertions of
the muscles which have already been divided should first engage the
attention of the student. These should be carefully defined and the
precise extent of each studied. Begin with the omo - hyoid, which
springs from the superior border of the scapula ; then deal in the same
way with the levator anguli scapula, rhomboiaeus minor and major, which
are attached to the vertebral border of the bone, and the serratus magnus,
which is inserted into the ventral aspect of the superior and inferior angles,
and the intervening portion of the vertebral border of the scapula. The
insertion of the pectoralis minor into the coracoid process, and of the
trapezius into both clavicle and scapula, should also be thoroughly ex-
amined. When this has been done these divided muscles may be removed,
with the exception of about half an inch of each, which it is advisable to
leave attached to the bones for future reference.
Dissection. — A block should now be placed in the axilla, and the skin
removed from the upper and outer aspects of the shoulder as low down as
the insertion of the deltoid. Commence in front and proceed from before
backwards, taking care to leave the fatty superficial fascia in its place.
Cutaneous Nerves. — In the superficial fascia, which is thus
laid bare, cutaneous nerves from two different sources must be
secured and traced, in order that the area of skin supplied by
each may be recognised. They are : —
1. Acromial branches from the third and fourth cervical nerves.
2. Cutaneous branches from the circumflex nerve.
The acromial branches have already been observed cross-
ing the outer third of the clavicle and the insertion of the
trapezius under cover of the platysma. They have been
divided in removing the limb. If the cut ends be secured
and followed, they will be found to spread out over the
outer and back part of the upper portion of the deltoid
region.
The cutaneous branches of the circumflex nerve consist —
(a) of a large branch which turns round the posterior border
of the deltoid muscle, and (b) of several fine filaments from
the same source, which pierce the substance of the deltoid
muscle, and appear at irregular intervals on its surface. The
latter are difficult to secure, but the main branch can be
easily found by carefully dividing the superficial fascia along
the posterior border of the deltoid. On everting this border
very little dissection is required to expose the nerve hooking
round it about two and a half inches above the deltoid
insertion. It breaks up into branches which supply the skin
over the lower portion of the deltoid region.
Deep Fascia. — A firm but thin fascia covers the sub-
scapularis muscle. Into this some of the fibres of the
44
THE UPPER LIMB
serratus magnus are usually inserted at the vertebral border
of the scapula. The strongest and most conspicuous fascia
■
Outer end of clavicle
v,^— -Margin of acromion process
Mw&&im&k.^^ Pectoral is major
Cephalic vein
Deltoid
Cutaneous branches of circumflex
nerve piercing deltoid
Cutaneous branch 01
circumflex nerve
iceps
Wgsijr-' C>uter head of tricep-
Brachialis anticus
Upper external cutaneous branch
of musculo-spiral nerve
Cephalic vein
Lower external cutaneous branch
of musculo-spiral nerve
Tfj»- supinator longus
''lip- Tendon of triceps
ill
f Olecranon
Extensor carpi radialis longior
FlG. 18. — The Deltoid Muscle and the outer aspect of the Upper Arm.
in this region is that which covers the exposed part of the
infraspinatus muscle on the dorsal aspect of the scapula. It
is firmly attached to the limits of the fossa in which that
muscle lies, and presents other very apparent connections.
SHOULDER— SCAPULAR REGION 45
Thus a strong septum, proceeding from its deep surface, will
be noticed to dip in between the infraspinatus and teres
minor muscles, and then as it proceeds forwards it gives a thin
covering to the teres minor, teres major, and the deltoid. In-
deed, it may be said to split into two lamellae — a superficial
and a deep, — which as they pass forwards enclose between
them the deltoid muscle.
Dissection. — Depress the scapula and retain it in this position by means
of hooks. The fibres of the deltoid are thus rendered tense, and the coarse
fasciculi of the muscle may be cleaned.
Deltoid Muscle. — The deltoid muscle, as its name implies,
is triangular in form. It is composed of coarse fasciculi, and
covers the shoulder-joint. It arises from the anterior border
of the outer third or half of the clavicle (Fig. 3, p. 7), from
the outer border of the acromion process, and from the lower
border of the spine of the scapula (Fig. 21, p. 49). Its origin
closely corresponds with the insertion of the trapezius. The
fasciculi of which the muscle is formed converge rapidly as
they are traced downwards, and finally they present a pointed
tendinous insertion into the deltoid eminence on the middle
of the outer surface of the shaft of the humerus (Fig. 30,
p. 72). Its nerves of supply come from the circumflex nerve.
Dissection. — -The limb should now be placed on its posterior aspect, and
the posterior circumflex artery and the circumflex nerve traced backwards
through the quadrilateral space. The boundaries of the space at the same
time should be defined and cleaned.
Quadrilateral and Triangular Spaces. — The quadrilateral
space is purely the result of dissection ; it has no real
existence until the parts are artificially separated from each
other. When viewed from the front, the boundaries will
be seen to be formed — (a) externally, by the upper part of the
shaft of the humerus ; (b) internally, by the long head of the
triceps ; (c) above, by the lower margin of the subscapulars ;
(d) and below, by the upper border of the teres major. When
viewed from behind, the upper boundary of the quadrilateral
space will be seen to be formed by the teres minor; the
other boundaries are the same as those seen from the front.
The term triangular space is the name given to another
intermuscular interval which becomes apparent when the
muscles in this region are cleaned and separated. It is
placed nearer the inferior angle of the scapula, and the long
46
THE UPPER LIMB
head of the triceps intervenes between it and the quadrilateral
space. It is bounded above by the subscapularis ; below by
the teres major ; and externally by the long head of the
triceps. The dorsalis scapulce artery should be followed into
this space, and cleaned up to the point where it disappears
around the axillary border of the scapula under cover of the
teres minor.
Posterior scapular artery
Suprascapular artery and nerve
Coracoid process
Capsule of shoulder-joint
Tendon of supraspinatus
Tendon of infra-
spinatus
Subscapular artery
Descending branch
Dorsalis scapulse artery
Posterior circumflex artery and
circumflex nerve Nerve to teres minor
Fig. 19. — Dissection of the Posterior Scapular Region.
Dissection. — Having now traced the posterior circumflex artery and the
circumflex nerve as far as possible through the quadrilateral space, the
position of the limb should be reversed. Turn it so that its dorsal surface
is uppermost, and everting slightly the posterior border of the deltoid,
define the boundaries of the space as they are seen from behind. At the
same time clean the circumflex vessels and nerves as they issue from the
space to reach the deep surface of the deltoid muscle. Care must be taken
not to injure the branch which the circumflex nerve gives to the teres
minor.
The deltoid muscle may now be divided close to its origin and thrown
SHOULDER— SCAPULAR REGION 47
downwards ; in doing this preserve the acromial branch of the thoracic
axis which runs in the line of incision beneath the deltoid. A large bursa
which lies between the deltoid and upper aspect of the capsule of the
shoulder-joint must also be kept intact.
Parts under cover of the Deltoid. — The deltoid covers the upper
part of the humerus, and is wrapped round the shoulder-joint so as to
envelop it behind, externally, and in front. The full rounded appearance
of the shoulder will now be seen to be due to the muscle passing over the
expanded upper end of the humerus. When the head of the bone is
displaced the muscle passes more or less vertically downwards from its
origin, and the dislocation is recognised by the squareness or flatness of
the shoulder. Behind, the deltoid covers the muscles which arise from the
dorsal aspect of the scapula as they pass outwards to reach the great
tuberosity of the humerus ; in front, it covers the upper part of the biceps
muscle, and overlaps the coracoid process and the muscles attached to it.
In relation also to the deep surface of the deltoid are the circumflex vessels
and nerve.
Subacromial Bursa. — This is a large bursal sac which
intervenes between the acromion process and deltoid above,
and the upper aspect of the capsule of the shoulder-joint
below. It facilitates the play of the upper end of the
humerus with its capsule, on the under aspect of the acromion
process and deltoid. Pinch a portion of it up with the
forceps and make an incision into it.1 The finger may then
be introduced into its interior and its extent and connections
explored. In some cases it is divided by internal partitions
into two or more chambers or loculi.
Dissection. — The branches of the posterior circumflex artery and the
circumflex nerve should now be dissected out on the deep surface of the
deltoid muscle.
Circumflex Vessels. — The posterior circumflex artery (arteria
circumflexa humeri posterior) has been already observed to
arise within the axilla from the posterior aspect of the axillary
artery a short distance below the subscapular branch. It at
once proceeds backwards through the quadrilateral space,
and, winding round the surgical neck of the humerus, it is
distributed in numerous branches to the deep surface of the
deltoid muscle. Several twigs are also given to the shoulder-
joint and the integument. It anastomoses with the acromial
branch of the thoracic axis and the anterior circumflex artery,
1 If the wall of the bursa be quite entire a blowpipe may be thrust into
it. It can then be distended, and if unilocular it may be inflated to about
the size of a hen's egg. It varies, however, much in size in different
individuals.
48
THE UPPER LIMB
and also by one or more twigs which it sends downwards to
the long head of the triceps, with the superior profunda
branch of the brachial artery.
The termination of the anterior cirawiflex artery (arteria
circumflexa humeri anterior) can now be more satisfactorily
studied, and its anastomosis with the posterior circumflex
established if the injection has flowed well. By this ana-
stomosis the arterial ring which encircles the upper part of
the shaft of the humerus is completed.
Circumflex Nerve (nervus axillaris). — This nerve accom-
panies the posterior circumflex artery, and supplies — (a)
muscu/ar branches to the deltoid and teres minor ; \b) cutaneous
branches to the skin over the lower part of the deltoid ; and (c)
Transverse section of the
humerus immediately be-
low the tuberosities.
Axillary artery.
Posterior circumflex artery.
Anterior circumflex artery.
Circumflex nerve.
Articular branch.
Branch to teres minor.
Cutaneous branches.
Fig. 20. — Diagram of the Circumflex Vessels and Nerve.
an articular twig to the shoulder - joint. The following is
the manner in which it is distributed. It springs from the
posterior cord of the brachial plexus, and turning round the
lower border of the subscapularis, proceeds backwards with
the posterior circumflex artery through the quadrilateral space.
Reaching the posterior aspect of the limb, it divides into an
anterior and a posterior division. The articular branch takes
origin from the trunk of the nerve, and enters the joint below
the subscapularis muscle. The posterior division gives off the
branch to the teres minor, and after furnishing a few twigs
to the posterior part of the deltoid, is continued onwards
as the cutaneous nerve which has already been dissected
in the superficial fascia over the lower part of the deltoid
(Fig. 20).
The nerve to the teres minor is distinguished by the presence
SHOULDER— SCAPULAR REGION
49
of an oval gangliform swelling upon it. The anterior divisio?i
proceeds round the humerus with the posterior circumflex
artery, and ends near the anterior border of the deltoid. It is
distributed by many branches to the deep surface of this
muscle, whilst a few fine filaments piercing the deltoid reach
the skin.
Long head
of triceps
Groove for dorsal is
scapulae artery
Scapular slip of latissimus dorsi
Fig. 2i. — Dorsum of Scapula with the Attachments of the Muscles mapped out.
Teres Major. — The part which the teres major plays in
the formation of the quadrilateral and triangular spaces has
already been seen. It arises from the oval surface on the
vol. i — 4
50 THE UPPER LIMB
dorsum of the scapula close to the inferior angle of the
bone (Fig. 21, p. 49), and also from the septa which the fascia
infraspinata sends in to separate it from the infraspinatus
and teres minor muscles. It is inserted into the inner lip
of the bicipital groove on the upper part of the humerus (Fig.
30, p. 72). It is supplied by the lowest subscapular nerve.
Insertions of Latissimus Dorsi and Pectoralis Major. — The narrow,
band-like tendon of the latissimus dorsi lies in front of the insertion
of the teres major. From the lower margin of this a small fibrous slip,
will be observed passing downwards, beyond the lower margin of the teres
major, to find attachment to the long head of the triceps. This is a rudi-
ment of the dorsi-epitrochlearis muscle of the lower animals. The tendons
of the teres major and latissimus dorsi should now be separated from each
other. They will be found to be more or less adherent, and a small bursa
will be discovered between them. The insertion of the latissimus dorsi
into the bottom of the bicipital groove of the humerus may now be
satisfactorily studied.
The tendon of insertion of the pectoralis major, which is attached to the
outer lip of the bicipital groove, may also be conveniently examined at this
stage (p. 22). A separation of the sternal and clavicular portions of the
muscle will bring into view the two laminae which constitute the tendon,
and the following points may be noted in connection with these : — (a) that
they are continuous with each other below, or, in other words, that the
tendon is simply folded upon itself ; {b) that the posterior lamina extends
upwards on the humerus to a higher level than the anterior, and that a
fibrous expansion proceeds upwards from its superior border, to seek
attachment to the capsule of the shoulder-joint and the lesser tuberosity of
the humerus ; (c) that the lower border is connected with the fascia of the
upper arm.
Acromio-clavicular Articulation. — This is a diarthrodial
joint, and the ligaments which bind the bones together
are : —
Ligaments proper to the f I. Superior 1 ,
? • . rr j r . . capSuie.
joint, . . . ( 2. Inferior j r
Accessory ligaments — Coraco-clavicular [ *■ .,
1 fa ^ conoid.
The superior acromio-clavicular ligament is a broad band,
composed of stout fibres, which is placed on the upper
aspect of the joint. The inferior acromio-clavicular ligament
which closes the joint below is not so strongly developed.
In front and behind, these ligaments are connected with each
other so as to constitute a capsule. The joint should now
be opened, when it will be seen to be lined by a synovial
membrane. An imperfect interarticular fibiv-cartilage is also
usually present. It is wedge-shaped, and connected by its
base to the superior ligament, whilst its free margin is directed
downwards between the bones.
SHOULDER— SCAPULAR REGION 51
Coraco - clavicular Ligament. — This powerful ligament
binds the under surface of the clavicle to the base of the
coracoid process. When thoroughly cleaned and denned
it will be seen to consist of two parts, which are termed the
conoid and the trapezoid ligaments.
The conoid ligament (ligamentum conoideum), placed upon
the posterior and inner aspect of the trapezoid, is broad above
where it is attached to the conoid tubercle of the clavicle
(Fig. 14, p. 35), and somewhat narrower below at its attach-
ment to the inner part of the root of the coracoid process.
The trapezoid ligament (ligamentum trapezoideum) is the
anterior and external part. Above it is attached along the
trapezoid line of the clavicle (Fig. 14, p. 35), whilst below it
is fixed to the upper aspect of the coracoid process. In the
recess between these two ligaments a bursa will usually be found.
Coraco -acromial Arch. — It is necessary to examine this
arch at the present stage, as the next step in the dissection
will, in a great measure, destroy it. It is the arch which
overhangs the shoulder-joint and protects it from above. It
is formed by the coracoid process, the acromion process, and a
ligament — the coraco-acromial — which stretches between them.
The coraco-acromial ligament is a strong band of a some-
what triangular shape. By its base it is attached to the outer
border of the coracoid process, whilst by its apex it is attached
to the extremity of the acromion (Fig. 37, p. 86).
The coraco-acromial arch plays a very important part in
the mechanism of the shoulder ; it might almost be said to
form a secondary socket for the humerus. We have already
noted the large bursa which intervenes between the acromion
and the capsule of the shoulder-joint, to facilitate the move-
ments of the upper end of the humerus on the under surface
of the arch.
Dissection. — The supraspinatus, infraspinatus, and teres minor muscles
which arise from the dorsum scapulae, and the subscapulars, which takes
origin from the venter scapulae, may now be examined. In order to
obtain an uninterrupted view of the supraspinatus muscle, the acromion
process must be divided with the saw close to its junction with the spine of
the scapula (Fig. 19, p. 46).
Further, divide the fascia which covers the teres minor muscle, and
reflect it towards the infraspinatus. By this means the septum from the
fascia infraspinata, which dips in between the two muscle?, will be
demonstrated, and their separation rendered easy. Care must be taken
not to injure the dorsalis scapulae artery which passes between the teres
minor and the bone.
1 — 4 a
52 THE UPPER LIMB
Supraspinatus. — The supraspinatus muscle arises from the
inner two-thirds of the supraspinous fossa, and also to a slight
degree from the fascia supraspinata which covers it. ■ From
this origin the fibres converge as they pass outwards, and,
proceeding under the acromion process, they end in a short,
stout tendon, which is inserted into the uppermost of the three
impressions on the great tuberosity of the humerus (Fig. 30,
p. 72). This tendon is closely adherent to the capsule of the
shoulder-joint. The supraspinatus is covered by the trapezius,
and in the loose fat which intervenes between this muscle and
the fascia supraspinata some twigs of the superficial cervical
artery ramify. It is supplied by the suprascapular nerve.
Teres Minor. — This is the small muscle which lies along the
lower border of the infraspinatus. It arises from an elongated
flat impression on the dorsal aspect of the axillary border of
the scapula, and from the septa of the fascia infraspinata which
intervene between it and the two muscles between which
it lies, viz., the infraspinatus and teres major. It is inserted
into the lowest of the three impressions on the great tuberosity
of the humerus, and also, by fleshy fibres, into the shaft of
the bone for about half an inch below this (Fig. 33, p. 77).
Towards its insertion it is separated from the teres major
by the long head of the triceps. The teres minor is supplied
by a branch from the circumflex nerve.
Infraspinatus. — This muscle arises from the whole of the
infraspinous fossa, with the exception of a small part of it near
the neck of the scapula. It also derives fibres from the fascia
which covers it. Its tendon of insertion is closely adherent
to the capsule of the shoulder-joint, and is attached to the
middle impression on the great tuberosity of the humerus
(Fig. t,^, p. 77). It is supplied by the suprascapular nerve.
Subscapularis. — The subscapularis muscle arises from the
whole of the subscapular fossa, with the exception of a small
portion near the neck of the scapula ; it also takes origin
from the groove which is present on the ventral aspect of
the axillary border of the bone (Fig. 17, p. 41). Its origin
is strengthened by tendinous intersections, which are attached
to the ridges which are present on the venter scapulae. The
fleshy fibres thus derived converge upon a stout tendon, which
is inserted into the lesser tuberosity of the humerus ; a few
of the lower fibres, however, gain independent insertion into
the shaft of the humerus below the tuberosity (Fig. 30, p. 72).
SHOULDER— SCAPULAR REGION 53
As the muscle proceeds outwards to its insertion, it passes
under an arch formed by the coracoid process and the con-
joined origin of the short head of the biceps and coraco-
brachialis. By dissecting between the upper border of the
muscle and the root of the coracoid process, a bursa of some
size will be discovered. This bursa communicates with the
cavity of the shoulder -joint through an aperture in the
capsular ligament : in other words, it is directly continuous
with the synovial membrane which lines the joint. This can
readily be ascertained by making an incision through its wall.
An instrument can then be passed into the joint. The sub-
scapularis is supplied by the upper and lowest subscapular nerves.
Dissection. — The suprascapular artery and nerve must now be followed
to their distribution on the dorsum of the scapula. They have already
been traced to the upper border of the scapula. Divide the infraspinatus
muscle about an inch and a half from its insertion, taking care not to
injure the subjacent vessels. Pull the muscle cautiously backwards, and
its nerve of supply with the terminations of the suprascapular and dorsalis
>capulae vessels will be exposed. Treat the supraspinatus muscle in a
similar manner (Fig. 19, p. 46).
Suprascapular Artery (arteria transversa scapulae). — This
vessel enters the supraspinous fossa by passing over the liga-
ment which bridges across the suprascapular notch. It divides,
under cover of the supraspinatus muscle, into a supraspinous
and an infraspinous branch. The former supplies the supra-
spinatus muscle, and gives off the chief nutrient artery to
the scapula ; the latter proceeds downwards in the great
scapular notch, and under cover of the spino-glenoid liga-
ment, to reach the deep surface of the infraspinatus muscle
to which it is distributed.
At the upper border of the scapula the suprascapular
artery gives off a branch (the subscapular) which enters the
subscapular fossa under cover of the subscapulars muscle.
Suprascapular Nerve. — This nerve accompanies the artery
of the same name, but it enters the supraspinous fossa by
passing through the suprascapular notch, under cover of the
suprascapular ligament. It supplies the supraspinatus, and
ends in the infraspinatus muscle. It usually sends two articular
tivigs to the posterior aspect of the shoulder-joint, viz., one
while in the supraspinous fossa, and the second as it lies in
the infraspinous fossa.
Dorsalis Scapulae Artery (arteria circumflexa scapulae). —
This vessel has already been observed to arise from the
i—4 6
54 THE UPPER LIMB
subscapular branch of the axillary, and enter the triangular
space. While here, it supplies one or two ventral branches,
which pass under cover of the subscapular muscle to the
venter scapulae, and a larger inprascapular branch which runs
downwards in the interval between the teres major and teres
minor to the inferior angle of the scapula (Fig. 19, p. 46).
After these branches are given off, the dorsalis scapulae leaves
the triangular space by turning round the axillary border of the
scapula, under cover of the teres minor. It now enters the
infraspinous fossa, where it ramifies and supplies branches to
the infraspinatus muscle.
Anastomosis around the Scapula. — An important and free
anastomosis takes place around the scapula. Three main
blood-vessels take part in this, viz. — (a) the suprascapular ;
(b) the posterior scapular ; and (c) the subscapular.
The posterior scapular artery runs downwards in relation to
the base or vertebral border of the scapula, and dispenses
branches upon both the dorsal and ventral aspects of the
bone. The subscapular artery runs downwards and inwards
along the axillary border of the scapula, and at the inferior
angle some of its terminal branches anastomose with the
terminal twigs of the posterior scapular. The suprascapular
artery at the upper margin of the scapula is brought into
communication with the posterior scapular by an anastomosis
in the neighbourhood of the superior angle of the bone.
But still more distinct anastomoses take place upon the
dorsal and ventral aspects of the bone. In the supraspinous
fossa, branches of the suprascapular inosculate with twigs from
the posterior scapular ; whilst in the infraspinous fossa, free
communications are established between the dorsalis scapula,
the suprascapular, and the posterior scapular.
On the ventral aspect of the scapula, the ventral branch
of the suprascapular, the ventral branches of the dorsalis
scapulce, and the ventral branches of the posterior scapular,
join to form a network.
The importance of this free communication between the blood-vessels in
relation to the scapula will be manifest when it is remembered that two of
the main arteries, viz., the posterior scapular and the suprascapular,
spring indirectly from the first part of the subclavian; whilst the third,
viz., the subscapular, arises from the third part of the axillary. When,
therefore, a ligature is applied to any part of the great arterial trunk of
the upper limb, between the first stage of the subclavian and the third
part of the axillary, this anastomosis affords ample means of re-establishing
the circulation.
SHOULDER— SCAPULAR REGION
DO
Dissection. — Detach the subscapularis from the scapula and lift it out-
wards to its insertion. This will afford a better view of its relation to the
capsule of the shoulder-joint, and also of the subscapular bursa. In a
well-injected subject the ventral anastomosis can likewise be made out.
Suprascapular and Spino-glenoid Ligaments. — These are
two ligamentous bands, which are placed in relation to the
suprascapular artery and nerve. The suprascapular or trans-
verse ligament bridges across the suprascapular notch of the
scapula, and converts it into a foramen. It lies between
the artery and nerve : the former being placed above it, and
the latter below it. Not infrequently it is ossified. The
spino-gletioid ligament is a weaker band, which bridges across
the suprascapular artery and nerve as they pass through the
great scapular notch. On the one hand it is attached to the
spine of the scapula, and on the other to the upper part of
the neck of the scapula.
FRONT OF THE ARM.
In this dissection the following parts have to be
studied : —
1. Cutaneous vessels and nerves.
2. Brachial aponeurosis.
3. Brachial artery and its branches.
4. Median, ulnar, musculo-spiral, and musculo-cutaneous nerves
and branches of the last two.
5. Biceps, coraco-brachialis, and brachialis anticus muscles.
In conjunction with this dissection, it is convenient to
study the triangular space in front of the elbow, and also to
trace the cutaneous nerves to their ultimate distribution in
the skin of the forearm.
Surface Anatomy. — In a muscular limb the prominence
formed by the biceps muscle along the front of the upper
arm is very apparent. Every one is familiar with the rounded
swelling which it produces when powerfully contracted in the
living subject. On either side of the biceps there is a feebly
marked furrow, and ascending in each of these there is a
large superficial vein. In the outer furrow is the cephalic
vein ; in the lower part of the inner furrow the basilic vein.
1— 4 c
56
THE UPPER LIMB
In the upper part of the inner or basilic furrow there is an
elongated bulging produced by the subjacent coraco-brachialis
muscle. This is useful as a guide to the lower part of the
axillary and the upper part of the brachial artery, which lie
immediately behind and to the inner side of it. The
humerus is thickly clothed by muscles ; but towards its lower
part the two supracondyloid ridges, leading down to the
Fig. 23. — Relation of the
bones of the Elbow to the
surface. Posterior view ;
Fig. 22. — Relation of bones elbow bent,
of Elbow to the surface.
Posterior view ; elbow fully
extended.
condylar eminences, may be felt. The external ridge is the
more salient of the two, and therefore the more evident to
touch.
The bony points around the elbow require to be studied
with especial care. It is by a proper knowledge of the
normal relative positions of these that the surgeon is able to
distinguish between the different forms of fracture and dis-
location which so frequently occur in this region. First note
the internal condyle of the humerus. This constitutes a
prominence, appreciable to the eye ; grasp it between the
finger and thumb, and note that it inclines backwards as well
FRONT OF THE ARM 57
as inwards. In a well-developed arm, when fully extended,
the external condyle does not form a projection on the
surface, but can be felt at the bottom of a slight depression
on the posterior aspect of the limb. It becomes apparent to
the eye as a prominence when the elbow is semi-flexed. The
olecranon process of the ulna produces a marked projection
on the back of the elbow between the two condyles. It is
placed slightly nearer to the internal than to the external
condyle. The loose skin which covers the olecranon moves
freely over its subcutaneous surface, owing to the interposi-
tion of a synovial bursa. The different positions which are
assumed by the olecranon, in relation to the condyles of the
humerus in the movements of the forearm at the elbow-joint,
must be carefully examined. This can best be done by plac-
ing the thumb on one condyle, the middle finger on the
other, and the forefinger on the olecranon. The limb should
then be alternately flexed and extended, so as to make clear
the extent of the excursion performed by the olecranon. In
full extension at the elbow-joint the three prominences are
placed on the same straight line ; when the forearm is bent at
a right angle the three bony points are placed at the angles of
an equilateral triangle, the apex of which points downwards.
When the arm is extended a marked depression on the
back of the elbow indicates the position of the articulation
between the radius and the humerus. Immediately below
this the head of the radius lies close to the surface, and can
readily be felt, especially when it is made to roll under the
finger by inducing alternately the movements of pronation
and supination. The head of the radius is placed about an
inch below the external condyle.
As the skin of the forearm must be reflected in the pur-
suit of the cutaneous nerves, it is well, at this stage, to study
also the external anatomv of this segment of the limb. In its
J o
upper half the radius is deeply imbedded in muscles, but in
its lower half it can be felt, and its styloid process on the
outer side of the wrist can be readily distinguished. On the
dorsal aspect of the lower end of the radius immediately
above the radio-carpal joint, and nearer the radial than the
ulnar border of the limb, a prominent bony tubercle may be
felt. This is the high ridge which forms the outer wall of
the sharply cut groove on the back of the radius in which the
tendon of the extensor secundi internodii muscle plays.
5 8 THE UPPER LIMB
The sinuous posterior border of the ulna is subcutaneous,
and may be followed by the finger throughout its entire
length ; as the elbow is approached it leads directly on
to the subcutaneous surface on the back of the olecranon.
In cases of suspected fracture, therefore, this border affords
valuable information. The styloid process of the ulna
may be detected immediately above the wrist, and it should
be observed that this does not extend so low down as the
corresponding process of the radius. The rounded lower
end of the ulna makes a marked projection on the inner and
posterior aspect of the limb immediately above the wrist-
joint, and lying in the groove between it and the styloid
process the tendon of the extensor carpi ulnaris may be felt.
Reflection of Skin. — The skin should be removed from the limb as far
down as the wrist-joint. It is necessary to do this in order that a con-
nected view may be obtained of the cutaneous nerves and the superficial
veins. But at the same time the skin should not be cast aside, as it forms
a most efficient protective wrapping for the part even after it has been
detached. Make one long incision along the middle of the fore aspect of
the arm and the forearm down to the wrist. A second incision carried
transversely round the lower end of the forearm, immediately above the
wrist -joint, will enable the dissector to reflect the skin in two large flaps,
outwards and inwards. In the fatty superficial fascia which is then
exposed, the superficial structures may be traced. It is well to begin with
the nerves, as these are not so apparent, and therefore more liable to
injury than the veins. But the dissection of the veins should be carried
on concurrently with that of the nerves.
Cutaneous Nerves. — These are very numerous, and are
derived from several sources. In addition to the two internal
cutaneous nerves, and the terminal cutaneous part of the
musculo -cutaneous, which spring from the brachial plexus,
there are three branches derived from the musculo -spiral,
and one — the intercosto- humeral — from the second inter-
costal nerve. These seven nerves may be classified into an
inner and an outer group as follows : —
1. Upper external cutaneous branch of
musculo-spiral,
2. Lower external cutaneous branch of
musculo-spiral,
3. Cutaneous part of musculo -cuta-
neous.
1. Intercosto-humeral,
2. Internal cutaneous branch of mus-
culo-spiral,
3. Lesser internal cutaneous,
4. Internal cutaneous,
Distributed mainly
upon the outer
aspect of arm and
forearm.
Distributed mainly
upon the inner
aspect of arm and
forearm.
FRONT OF THE ARM 59
The two external cutaneous branches of the musculo-spiral
Acromial twigs from cervical plexus
Branches from circumflex
Internal branch of musculo-spiral
Intercosto-humeral
Branch from internal cutaneous X^
Lesser internal cutaneous
External cutaneous branches \
of musculo-spiral J
Internal cutaneous nerve
Cephalic vein
Basilic vein
Median basilic vein
Median cephalic vein
Musculo-cutaneous
Profunda vein
Radial vein
Ulnar vein
Median vein
Palmar cutaneous of median
Palmar cutaneous of ulnar
Palmar cutaneous of radial
Fig. 24. — Cutaneous N s on the Front of the Upper Limb.
pierce the deep fascia about the middle of the outer surface
of the upper arm immediately below the insertion of the
6o THE UPPER LIMB
deltoid, and in close relation to the external intermuscular
septum. The smaller upper branch appears a short dis-
tance above the other. It follows the cephalic vein, and
can be traced downwards as far as the elbow. Its filaments
are distributed to the skin over the outer and anterior part of
the lower half of the upper arm. The larger lower bra?ich
can be followed as far as the wrist, and not infrequently its
terminal filaments even reach the dorsum of the hand. It
supplies the skin on the dorsal aspect of the forearm.
It should be borne in mind that the skin on the outer
aspect of the limb, above these nerves and over the deltoid,
is supplied by the cutaneous branches of the circumflex
nerve and the supra-acromial branches of the cervical plexus
(P- 43>
The terminal cutaneous branch of the musculocutaneous will
be found in front of the elbow-joint. It pierces the deep
fascia on the outer side of the tendon of the biceps. It is a
large nerve, and proceeds downwards behind the median
cephalic vein. The skin both upon the anterior and posterior
aspects of the outer side of the forearm is supplied by this
nerve, and it is distributed by two main branches. The
larger anterior branch can be traced as far as the skin over
the ball of the thumb. A few of its terminal twigs pierce the
fascia above the wrist, and join the radial artery, by which
they are conducted to the back of the carpus. The posterior
branch may be followed on the dorsal aspect of the limb as
far as the wrist.
The intercosto-humeral nerve can usually be traced half-way
down the upper arm ; but the area of skin which it supplies
is somewhat variable. The internal cutaneous branch of the
musculo-spiral proceeds downwards and backwards on a deeper
plane, and crosses under the intercosto-humeral. Its fila-
ments extend upon the back of the upper arm as low as the
elbow-joint.
The small internal cutaneous nerve, or nerve of Wrisberg,
will be found piercing the deep fascia, to become superficial,
half-way down the inner side of the upper arm. Its twigs
may be followed, in the superficial fascia, as far as the
olecranon process.
On the inner side of the upper arm, on its dorsal aspect,
three nerves therefore have been traced. From within out-
wards these are : the nerve of Wrisberg, the intercosto-
FRONT OF THE ARM
61
humeral, and the inner cutaneous branch of the musculo-
spinal (Fig. 25).
Acromial branches of cervical
plexus
Cutaneous branch of the
circumflex
/ Internal cutaneous branch of
™. I musculo-spiral
/Upper external cutaneous
( branch of musculo-spiral
Intercosto-humeral
Lesser internal cutaneous
Lovver'external branch of musculo-
spiral
Posterior branch of internal cutaneous
Posterior branch of musculo-cutaneous
-Radial
- Dorsal branch of ulnar
Fig. 25. — Cutaneous Nerves on the Posterior Aspect of the Upper Limb.
The internal cutaneous nerve is chiefly destined for the
supply of the skin of the forearm. It appears through the
62 THE UPPER LIMB
deep fascia half-way down the inner side of the upper arm
close to the basilic vein, and a short distance in front of the
nerve of Wrisberg. It at once divides into an anterior and
a posterior branch. The anterior branch runs downwards
behind (but sometimes in front of) the median basilic vein,
and it is distributed to the skin over the inner and anterior
aspect of the forearm. The posterior branch, inclining in-
wards, proceeds downwards in front of the internal condyle
of the humerus, to reach the skin on the inner and dorsal
aspect of the forearm.
A small twig is frequently given by the internal cutaneous
nerve to the skin over the biceps muscle. This pierces the
deep fascia close to the axilla.
Superficial Veins. — The superficial veins in front of the
forearm and upper arm may now be followed ; but in all
probability they are already for the most part exposed.
Four veins will be seen ascending upon the anterior and
lateral aspects of the forearm, viz., the radial vein upon the
outer border ; the anterior and posterior ulnar veins upon the
inner border ; and the median vein upon the front of the
forearm. When the median reaches the hollow in front of
the elbow, it is joined by a short wide vein, which appears
through the deep fascia, and establishes a connection between
the median and the deep veins of the forearm. This con-
necting trunk is called the profunda vein. After receiving
this tributary, the median at once divides into two branches,
which diverge widely from each other, like the limbs of the
letter V. The inner branch is called the median-basilic ; the
outer the median-cephalic.
The ??iedian- basilic is a short wide vessel which passes
upwards and inwards, and as it approaches the front of the
internal condyle of the humerus it is joined by the two ulnar
veins. These may enter it separately ; but more commonly
the anterior ulnar vein joins the larger posterior ulnar vein
in the upper part of the forearm, so as to form a common
trunk, with a single opening into the median-basilic. The
large vein, resulting from the union of the median-basilic
and the two ulnar veins, is termed the basilic vein. The
median-basilic is the vein which is commonly selected when
the surgeon has recourse to venesection ; and formerly, when
the practice of bloodletting was more common than it is
now, the relations of this vein were a matter of high
FRONT OF THF ARM 63
importance. The dissector should observe the following
points in regard to it: — (1) that it crosses a thickened
piece of the deep fascia, termed the bicipital fascia ; (2) that
this fascia separates it from the brachial artery, which it also
crosses ; and (3) that the anterior part of the internal cutaneous
nerve lies behind it, although in many cases it may cross in
front of it.
The median-cephalic vein is not so large as the median-
basilic, and it generally ascends with a greater degree of
obliquity. It crosses in front of the cutaneous branch of
the musculo-cutaneous nerve, and is joined by the radial
vein. The resulting trunk is called the cephalic vein.
The basilic vein runs upwards on the inner aspect of the
upper arm in the slight furrow which marks the limb along
the inner margin of the biceps. Half-way up the upper
arm it disappears by piercing the fascia close to the spot
where the internal cutaneous nerve emerges. At the lower
border of the posterior wall of the armpit the basilic forms
the axillary vein.
The cephalic vein ascends in the groove along the outer
margin of the biceps. Its further course has been previously
noted. It extends upwards in the interval between the deltoid
and the clavicular part of the pectoralis major. It dips back-
wards through the costo-coracoid membrane, crosses the first
part of the axillary artery, and finally opens into the axillary vein.
Lymphatic Glands. — If the superficial fascia be searched
upon the inner side of the limb, and immediately above the
elbow, one or two minute lymphatic glands in relation to the
basilic vein will be found. These are of interest to dissectors,
as they are the first to enlarge and become painful in cases
of dissection-wound.
Brachial Aponeurosis (fascia brachii). — The deep fascia
should now be cleaned by the removal of the fatty superficial
layer. It forms a continuous envelope around the upper
arm, but at no point does it show a great density or strength.
Above, it is continuous with the axillary fascia, and the fascia
covering the pectoralis major and the deltoid. The tendons
of these two muscles are closely connected with it — a certain
proportion of their tendinous fibres running directly into it.
Below, it is firmly fixed to the bony prominences around
the elbow, and in front it receives an accession of fibres
from the tendon of the biceps. These fibres constitute the
64
THE UPPER LIMP
bicipital or semilunar fascia, and form a very distinct band
which, continuous with the fascia above and below, bridges
across the brachial artery, and is lost upon the pronator
radii teres muscle on the inner side of the forearm.
The brachial aponeurosis may be reflected by making an incision
through it along the middle line of the front of the arm. In throwing the
inner portion inwards, the dissector must leave the bicipital fascia in
position. This may be done by separating it artificially from the general
aponeurosis by an incision above and below it.
As the foregoing dissection is proceeded with, it becomes
evident that septa or partitions pass in between the muscles
External inter-
muscular septum
Internal inter-
muscular septum
Fig. 26. — Diagram (after Turner) to show how the Upper
Arm is divided by the intermuscular septa and bone into an
anterior and posterior compartment. These compartments
are represented in transverse section.
from the deep surface of the investing brachial aponeurosis.
Two of these possess a superior strength, and obtain direct
attachment to the humerus. They are the external -and
internal intermuscular septa. The connections of these
cannot be fully studied at present, but it is important that
the student should understand their relations at this stage.
In the course of the dissection of the upper arm they will
gradually be displayed.
The i?iternal i?iter muscular septu?n is the stronger and more
distinct of the two. It is attached to the internal supra-
condyloid ridge, and may be followed upwards as high as
the insertion of the coraco-brachialis muscle. The external
intermuscular septiwi is fixed to the external supracondyloid
ridge, and extends up the arm as high as the insertion of
FRONT OF THE ARM
65
the deltoid. The dissector should note that these septa
divide the upper arm into an anterior and a posterior osteo-
fascial compartment.
Structures in the Anterior Compartment. — The anterior
osteo- fascial compartment of the upper arm has been opened
into by the reflection of the front part of the brachial
aponeurosis. The three muscles which specially belong to
this region are the biceps, brachialis anticus, and the coraco-
brachialis. The biceps is the most superficial muscle : under
Cephalic vein
Musculocutaneous
nerve
Brachial vessels
Basilic vein
Median nerve
Internal inter-
muscular septum
Ulnar nerve
Musculo-spiral nerve
External inter-
muscular septum
Fig. 27. — Transverse section through the Lower Third of the
Right Upper Arm.
cover of it, and closely applied to the anterior aspect of
the humerus, is the brachialis anticus ; whilst the coraco-
brachial is the slender muscular belly which lies along the
inner side of the biceps in its upper part. But, in addition,
two muscles of the forearm will be observed extending upwards
into this compartment of the arm, to seek origin from the
external supracondyloid ridge of the humerus : they are the
supinator longus and the extensor carpi radialis longior. They
are closely applied to the outer side of the brachialis anticus.
The brachial artery, with its venae comites, extends through
the region in relation to the inner margin of the biceps, and
all the terminal branches of the cords of the brachial plexus,
with the exception of the circumflex, will be found for some
vol. 1 — 5
66 THE UPPER LIMB
part of their course in this region. The musculo-spiral, it
is true, almost at once proceeds to the back of the limb, but
it again comes to the front, and may be found in the lower
part of the outer side of the arm, by separating the origins
of the supinator longus and extensor carpi radialis longior
from the brachialis anticus, and dissecting deeply in the
interval between them.
Dissection.— -In carrying out this somewhat extensive dissection, the
main object of the dissector should be to keep the brachial artery as un-
disturbed as possible until he has satisfied himself as to its relations. He
is therefore, in the first instance, advised to clean only those parts of the
muscles which are in immediate relationship to the vessel and its branches.
The divided brachial nerves, with the axillary artery and vein, should be
arranged in proper order, and then tied to a small piece of wood about \\
inches long {e.g. , a piece of a penholder), held transversely. By means of
a loop of string this can then be fastened to the coracoid process. By
this device the dissection of the upper arm will be greatly facilitated.
The dissection of the entire length of the brachial artery should be carried
out at one and the same time, and its termination in the radial and ulnar
arteries should be defined.
Brachial Artery (arteria brachialis). — The brachial artery
is the direct continuation of the axillary trunk into the upper
arm. It therefore begins at the lower border of the teres
major, and it proceeds downwards to a point a short distance
below the bend of the elbow, where it ends opposite the neck
of the radius by dividing into two terminal branches — the
radial and the ulnar arteries. The course which it pursues
is not a straight one : at first it lies upon the inner side of
the limb, but it gradually, as it descends, inclines outwards so
as to lie finally in front of the arm.
This change of direction must be borne in mind when pressure is
applied to the vessel, with the view of controlling the flow of blood within
it. Thus, above, the pressure must be directed in an outward and back-
ward direction, so that it may be caught between the fingers and the bone ;
whilst below, the pressure must be applied in a backward direction.
Throughout its whole length, the brachial artery is super-
ficial : in other words, in order to expose the vessel the skin
and fascia alone would require to be removed. The inner
margins of the coraco-brachialis and the biceps muscles,
however, which lie along its outer side, overlap it to a con-
siderable extent, and finally, in the antecubital fossa, it sinks
deeply in the interval between the supinator longus on the
outside, and the pronator radii teres on the inside. The
extent to which the brachial artery is overlapped by the
FRONT OF THE ARM
67
biceps may be seen in the accompanying woodcut (Fig. 28).
At the bend of the elbow it is crossed by the bicipital fascia,
which, as previously stated, intervenes between it and the
median-basilic vein. The basilic vein, in its lower part, is
separated from the artery by the deep fascia. It does not lie
immediately over it, but to its inner side (Figs. 27 and 28).
Higher up, after the vein has pierced the fascia, it comes into
closer relationship with the artery. Two venae comites are
closely applied to the brachial artery, and the numerous con-
Cephalic vein
Median nerve
Brachial artery
Basilic vein
I Musculo-spiral
nerve
- Superior profunda
vessels
Ulnar nerve
Fig. 28. — Transverse section through the middle of the Right Upper Arm.
necting branches which pass between these veins cross over
and under the vessel, so as to make the relationship still more
intimate.
Be/iind, the brachial artery is supported by a succession of
structures, as we trace it from above downwards. First, it
lies in front of the long head of the triceps, but here the
musculo-spiral nerve and the superior profunda artery arc
interposed ; next, it rests upon the inner head of the triceps ;
then upon the insertion of the coraco-brachialis ; and lastly,
for the remainder of its course, upon the brachialis anticus.
With the exception of the musculo-cutaneous, all the large
nerves of the arm will be seen to lie, for a certain part of
68 THE UPPER LIMB
their course, in relation to the brachial artery. The median
accompanies it closely throughout its whole length. At first
it lies in front, and to the outer side of the vessel ; towards the
middle of the arm it crosses superficially to the vessel. ; from
this onwards it is placed along its inner side. The ulnar and
internal cutaneous nerves lie close to its inner side, as far as the
insertion of the coraco-brachialis, and then they leave the
artery. The former inclines backwards, and, piercing the
internal intermuscular septum, enters the posterior compart-
ment of the arm. The internal cutaneous nerve, on the other
hand, inclines forwards, and becomes superficial by piercing
the brachial aponeurosis. The musculo-spiral, for a very short
distance, is placed behind the brachial artery, as it lies in
front of the long head of the triceps, but soon it leaves the
vessel by disappearing in the interval between the long and
inner heads of the triceps.
Branches of the Brachial Artery. — A considerable number
of branches spring from the brachial artery. Those which
arise from its outer aspect are irregular in number, origin,
and size. They are termed the external branches, and are
distributed to the muscles and integument on the front of the
arm. The series of internal branches which proceed from the
inner and posterior aspect of the parent trunk are named as
follows as we meet them from above downwards : —
3. Nutrient.
4. Anastomotica magna.
The superior profunda (arteria profunda brachii) is the
largest of the branches which spring from the brachial trunk.
It takes origin about an inch or so below the lower margin of
the teres major, and associates itself with the musculo-spiral
nerve, which it accompanies to the back of the arm. Con-
sequently, only a short part of the vessel is seen in the
present dissection. It soon disappears from view between the
long and inner heads of the triceps.
The ijiferior profunda (arteria collateralis ulnaris superior)
is a long slender artery, which can be recognised from the
fact that it follows closely the course which is pursued by the
ulnar nerve. Its origin is somewhat uncertain. As a general
rule, it issues from the brachial artery opposite the insertion
of the coraco-brachialis, but very frequently it will be seen to
arise in common with the superior profunda. It pierces the
internal intermuscular septum, with the ulnar nerve, and
1. Superior profunda.
2. Inferior profunda.
FRONT OF THE ARM
69
descends behind this aponeurotic partition to the interval
between the olecranon and the internal condyle of the
humerus.
The nutrient artery to the humerus (arteria nutritia humeri)
Musculo-spiral
nerve
Anterior branch
of superior
profunda artery
External head of
triceps
Nerve to outer
head of triceps
- ^ Cutaneous
I branches of
J musculo-
spiral nerve
Posterior branch
_ of superior
profunda artery
Fig. 29. — Diagram to show relation of Musculo-spiral Nerve to the Humerus
and of Vessels and Nerves to the Intermuscular Septa.
may arise directly from the brachial trunk, or take origin from
the inferior profunda. It should be sought for at the lower
border of the insertion of the coraco-brachialis, and the dis-
sector should not be satisfied until he has traced it into the
medullary foramen of the bone. When the nutrient artery
is not seen in its usual position, it will probably be found in
7o THE UPPER LIMB
the dissection of the back of the arm, taking origin from the
superior profunda.
The anastomotica magna (arteria collateralis ulnaris inferior)
arises about two inches above the bend of the elbow, and runs
inwards upon the brachialis anticus. It soon divides into a
small anterior and a larger posterior branch. The a?iterior
branch is carried downwards in front of the internal condyle
of the humerus in the interval between the brachialis anticus
and the pronator radii teres. It anastomoses in this situa-
tion with the anterior ulnar recurrent artery. The posterior
branch pierces ihe internal intermuscular septum, and will be
seen later on in the posterior compartment of the arm.
The two Internal Cutaneous Nerves. — Very little more
requires to be said about these nerves. Their origin within
the axilla has already been noted, and they have been traced
to their distribution from the points where they pierce the
investing brachial aponeurosis. It only remains for the dis-
sector to examine them in that part of their course in which
they lie under cover of the brachial aponeurosis. It will be
observed that they both lie along the inner side of the
brachial artery. The nerve of IVrisberg, or lesser i?iter?ial
cutaneous nerve, gives off, as a rule, no branches in this situation,
except one or more twigs of communication to the intercosto-
humeral. The internal cutaneous gives off the branch which
pierces the fascia to supply the skin in front of the biceps.
Median and Ulnar Nerves. — These large nerve trunks do
not furnish any branches in the upper arm. The median
(nervus medianus) arises in the axilla by two heads from the
outer and inner cords of the brachial plexus. It proceeds
downwards upon the outer and superficial aspect of the
axillary and brachial arteries, until it approaches the level of
the insertion of the coraco-brachialis. Here it lies in front of
the artery. Finally, it reaches the inner side of the vessel,
and maintains this position for the rest of its course in the
upper arm.
The ulnar nerve (nervus ulnaris) is the largest branch of
the inner cord of the brachial plexus. It descends upon the
inner side of the axillary and brachial arteries, and at the
insertion of the coraco-brachialis it encounters the inferior
profunda artery. Accompanied by this vessel, it now leaves
the brachial artery by passing backwards through the internal
intermuscular septum, and it is continued downwards upon
FRONT OF THE ARM 71
the posterior aspect of this aponeurotic partition, to the
interval between the olecranon and internal condyle of the
humerus.
Dissection. — The muscles should now be thoroughly cleaned, and the
musculo-cutaneous nerve and its branches dissected out.
Musculo-cutaneous Nerve (nervus musculocutaneus). — The
musculo-cutaneous nerve arises from the outer cord of the
brachial plexus, at the lower border of the pectoralis minor.
Inclining outwards, it perforates the coraco-brachialis, and
appears between the biceps and the brachialis anticus. It
proceeds obliquely downwards between these muscles until
it reaches the bend of the elbow, where it comes to the
surface at the outer border of the tendon of the biceps.
From this point onwards it has already been traced as a
cutaneous nerve of the forearm (p. 60).
In the upper arm the musculo-cutaneous supplies branches
to the three muscles in this region. The branch to the
coraco-brachialis is given off before the parent trunk enters
the substance of the muscle ; the branches to the biceps and
brachialis anticus issue from it, as it lies between them.
Coraco-brachialis. — This is an elongated muscle, which
takes origin from the tip of the coracoid process in conjunction
with the short head of the biceps. It proceeds downwards
along the inner margin of the biceps, and obtains insertion
into a linear ridge situated upon the inner aspect of the shaft
of the humerus about its middle.
Biceps (musculus biceps brachii). — The biceps muscle
arises from the scapula by two distinct heads of origin. The
short or inner head (caput breve) springs from the tip of the
coracoid process in conjunction with the coraco-brachialis
(Fig. 17, p. 41). The long or outer head (caput longum) is
a rounded tendon, which occupies the bicipital groove of the
humerus. Its origin cannot be studied at this stage of the
dissection, because it is placed within the capsule of the
shoulder-joint. Suffice it for the present to say, that it arises
from an impression on the scapula immediately above the
glenoid fossa. Both heads swell out into elongated fleshy
bellies, which are closely applied to each other, and afterwards
unite in the lower third of the arm. Towards the bend of
the elbow the fleshy fibres converge upon a stout, short
tendon, which is inserted into the posterior part of the
72
THE UPPER LIMB
Supraspinatus
" *
Latissimus dorsi
Pectoralis major
Teres major
Deltoid
' 11
rL^
Coraco-brachialis
Extensors
Fig. 30. — Anterior aspect of Humerus
with Muscular Attachments mapped
out.
SubscapuiaHs tuberosity of the radius.
This insertion will be more
fully examined at a later
period, but it may be
noticed in the meantime
that the tendon is twisted
so as to present its mar-
gins to the front and back
of the limb, and further,
that a synovial bursa is in-
terposed between it and
the anterior smooth part of
the radial tuberosity.
The dissector has already
taken notice of the bicipital
or semilu?iar fascia, and has
separated it artificially from
the brachial aponeurosis
above, and from the deep
fascia of the forearm below.
Observe now that it springs
from the anterior margin
of the tendon of the biceps,
and that it likewise receives
some muscular fibres from
the short head of the
muscle.
Brachialis Anticus (mus-
eums brachialis). — The
brachialis anticus arises
from the entire width of
the anterior surface of the
lower half of the shaft of
the humerus, from the in-
ternal intermuscular
septum, and from a small
part of the external inter-
Pronator radii teres muscular septum above the
supinator longus. The
origin from the bone is
prolonged upwards in two
slips which partially em-
Supinator longus
isor carpi
ongior
FRONT OF THE ARM
73
brace the insertion of the deltoid. The fibres converge to
be inserted into the base of the coronoid process of the ulna
by a short, thick tendon. The muscle lies partly under
Outer end of clavicle
Margin of acromion process
Pectoralis major
^ Cephalic vein
Deltoid
Cutaneous branches of circumflex
nerve piercing deltoid
Cutaneous branch of
circumflex nerve
Hp Biceps
Outer head of triceps
irachialis amicus
I Upper externa! cutaneous branch
f musculo-spiral ner\e
j^S. Cephalic vein
Lower external cutaneous branch
of musculo-spiral nerve
Supinator longus
endon of triceps
Olecranon
Extensor carpi radialis longior
Fig. 31. — The Deltoid Muscle and the outer aspect of the Upper Arm.
cover of the biceps, but projects beyond it on either side.
It is overlapped on its inner side by the pronator radii teres,
and on the outer side by the supinator longus and extensor
carpi radialis longior. Its deep surface is closely connected
74 THE UPPER LIMB
to the anterior ligament of the elbow-joint. Its chief nerve
of supply, from the musculo -cutaneous, has already been
secured, but it also receives one or two small twigs from the
musculo-spiral, which are given off under cover of the supinator
longus.
Dissection. — Separate the supinator longus muscle from the braehialis
anticus, and dissect out the musculo-spiral nerve, and the anterior terminal
branch of the superior profunda artery, which lie deeply in the interval
between them. Here also the anastomosis between the superior profunda
and the radial recurrent arteries may be made out, in a well-injected
subject ; and the twigs which are given by the musculo-spiral nerve to the
braehialis anticus, supinator longus, and extensor carpi radialis longior,
should be looked for.
Triangular Space in front of the Elbow (antecubital
fossa). — This is a slight hollow in front of the elbow-joint.
It corresponds to the popliteal space of the lower limb, and
within its area the brachial artery divides into its two terminal
branches. In the first instance, let the dissector consider the
structures which cover it. These have already been removed,
and consist of skin, superficial fascia, and deep fascia. In
connection with the latter is the semilunar fascia, whilst within
the superficial fascia are the median-basilic and median-
cephalic veins, the anterior division of the internal cutaneous
nerve and the cutaneous part of the musculo-cutaneous nerve.
These structures constitute the coverings of the space.
The space is triangular. Its base is directed upwards,
and is usually regarded as being formed by a line drawn
between the two condyles of the humerus. Its inner bou?idary
is the pronator radii teres, and its outer boundary the supinator
longus. The meeting of these two muscles below constitutes
the apex. The boundaries should now be thoroughly cleaned,
and then the co?ite?its of the space may be dissected.
Within the space, as we have already stated, there is the
termination of the brachial artery, with the radial and ulnar
branches into which it divides. To the outer side of the
main vessel is placed the tendon of the biceps, and to its
inner side the median nerve. A quantity of loose fat is
also present. The ulnar artery leaves the space by passing
under cover of the pronator radii teres ; the radial artery
is continued downwards beyond the apex of the space,
overlapped by the supinator longus. The median nerve
disappears between the two heads of the pronator radii
teres, and the tendon of the biceDS inclines backwards
FRONT OF THE ARM
75
between the two bones of the forearm, to reach its insertion
into the radial tuberosity.
When the fatty tissue has been thoroughly removed the
floor of the space will be revealed. This is formed by the
brachialis anticus and the supinator brevis muscles. In this
Lymphatic gland
Internal cutaneous
nerve
Semilunar fascia
Brachial artery
Ulnar artery
Tendon of biceps
Median nerve
Nerve to supinator
lonsrus
^ — Musculo-spiral nerve
Musculocutaneous
nerve
Posterior interosseous
nerve
Radial nerve
Radial recurrent
artery
Radial artery
Supinator brevis
Fig. 32. — Dissection of the Antecubital Fossa.
situation the brachialis anticus is closely applied to the
anterior aspect of the elbow-joint, whilst the supinator brevis
is wrapped round the upper part of the radius.
Now divide the bicipital fascia, and separate the bounding
muscles widely from each other. Other structures come into
view, but they cannot, strictly speaking, be regarded as lying
within the space proper. They are — (1) the musculo-spiral
nerve, the anterior branch of the superior profunda artery,
76 THE UPPER LIMB
and the recurrent branch of the radial artery, lying deeply
in the interval between the supinator longus and the brachialis
anticus ; (2) the anterior branch of the anastomotica magna,
and the anterior ulnar recurrent branch of the ulnar artery,
placed under cover of the pronator radii teres.
BACK OF THE ARM.
In this region the following are the structures which require
to be studied : —
1. The triceps muscle.
2. The superior profunda artery, and the musculo-spiral nerve.
3. The inferior profunda artery, and the ulnar nerve.
4. The posterior branch of the anastomotic artery.
5. The subanconeus muscle.
Dissection. — The skin has already been removed from the back of the
arm. The deep fascia should now be raised from the surface of the triceps
muscle, and its three heads cleaned and isolated from each other. To
place the muscle on the stretch, the inferior angle of the scapula should be
raised as high as possible, and the forearm flexed at the elbow-joint. The
musculo-spiral nerve, together with the superior profunda artery, must at
the same time receive the attention of the dissector. They should be
followed backwards between the heads of the triceps, and all their branches
should be carefully preserved.
Triceps (musculus triceps brachii). — This muscle occupies
the entire posterior osteo-fascial compartment of the upper
arm. It arises by a long or middle head from the scapula, and
by two short heads, outer and inner, from the humerus. The
fleshy fibres of these three heads join a common tendon,
which is inserted into the top of the olecranon process of
the ulna. The superficial part of the muscle is, for the most
part, formed by the long scapular head and the outer humeral
head of the muscle. The inner humeral head is deeply
placed ; only a very small portion of it appears superficially
in the lower part of the arm on each side of the common
tendon of insertion.
The long or scapular head (caput longum) of the triceps,
arises by a flattened tendon, from the rough triangular
impression on the upper part of the axillary border and the
lower aspect of the neck of the scapula (Fig. 17, p. 41). This
tendon takes origin in the interval between the teres minor
and subscapularis muscles.
BACK OF THE ARM
71
Teres minor
Infraspinatus
Triceps (outer
head)
Deltoid-
Brachialis anticus -
Musculo-spiral
groove
The two humeral
heads take origin from
the posterior aspect of
the humerus ; and if it
be borne in mind that
no fibres arise from the
musculo -spiral groove,
and that this groove in-
tervenes between the
origins of these heads,
their connections will
be easily understood.
The dissector should
provide himself with a
humerus, and, having
first identified the mus-
culo-spiral groove, pro-
ceed to map out the
areas of attachment of
the humeral heads of
the triceps as they are
exhibited in the dis-
sected part.
The outer head (caput
laterale) of the triceps
arises from the outer
and posterior aspect of
the shaft of the hu-
merus, above the level
of the musculo - spiral
groove. It takes origin,
by short tendinous
fibres, along a line
which descends vertic-
ally from the insertion
of the teres minor above
to the upper border of
the musculo-spiral
groove below. But it
also derives fibres from
a strong aponeurotic
bridge or arch, which is thrown over the groove, so as to
Anconeus
Fig. 33. — Posterior aspect of Humerus with
Attachments of Muscles mapped out.
78 THE UPPER LIMB
give protection to the superior profunda artery and the
musculo-spiral nerve. The strength and position of this arch
can be tested by thrusting the handle of the knife downwards
and outwards in the musculo-spiral groove, and along the
course of the nerve and artery under the external head of the
triceps. By its lower end the arch is connected with the
external intermuscular septum.
The inner head (caput mediale) of the triceps is placed
below the musculo-spiral groove. It sends upwards, on the
posterior aspect of the humerus, and along the inner margin
of the groove, a narrow pointed fleshy slip, which obtains
origin from the bone as high as the insertion of the teres
major muscle. Below, it widens out and arises by short fibres
from the entire breadth of the posterior surface of the
humerus. It also springs from the posterior surface of
the internal intermuscular septum, and from the lower part
of the corresponding surface of the external intermuscular
septum. The inner head of the triceps, therefore, has very
much the same origin from the back of the bone that the
brachialis anticus has from the front of the bone.
The dissector should now study the common tendon of
insertion of the triceps. The long and the outer heads end
in a broad, flat tendon, which is inserted into the back part of
the upper surface of the olecranon process, and at the same
time gives off, on the outer side, a strong expansion to the
fascia of the forearm as it covers the anconeus muscle. The
short fleshy fibres of the inner head are, for the most part,
inserted into the deep surface of the common tendon, but a
considerable number find direct attachment to the olecranon,
whilst a few of the deepest fibres are inserted into the loose
posterior part of the capsule of the elbow-joint. These latter
fibres have been described as a separate muscle under the
name of subanconeus. The triceps is supplied by branches
from the musculo-spiral nerve.
Dissection. — In order .that the musculo-spiral nerve and the superior
profunda artery may be fully exposed, the external head of the triceps
must be divided. Thrust the handle of a knife along the musculo-spiral
groove, and under the muscle. This will give the direction in which the
outer head of the triceps should be severed. Beyond cleaning the nerve
and its branches, and the superior profunda artery, as they lie in the groove,
no further dissection is necessary.
Musculo-spiral Nerve (nervus radialis). — The musculo-spiral
is the direct continuation of the posterior cord of the brachial
BACK OF THE ARM
79
plexus after it has furnished in the axilla the three subscapular
and the circumflex nerves. In the first instance, the musculo-
spiral proceeds downwards behind the lower part of the axillary
Posterior circumflex artery and
circumflex nerve
Inner head of triceps
Brachial artery
Musoulo-spiral nerve
gfr- Nerve to anconeus
_ Nutrient artery entering bone in
^^Sj^ the musculo-spiral groove
§§L- Inner head of triceps
s£ Superior profunda artery
|>I — Fibrous arch
Posterior branch of superior
profunda artery
Fig. 34. — Dissection of the posterior aspect of Upper Arm. The outer
head of the Triceps has been divided so as to expose the Musculo-spiral
Groove of Humerus.
artery and the upper part of the brachial artery. It soon
leaves the front of the arm, however, and, inclining backwards
with the superior profunda artery, enters the interval between
the long and the inner heads of the triceps, and reaches
the musculo-spiral groove. In this it is conducted round the
8o THE UPPER LIMB
back of the shaft of the humerus, under cover of the outer
head of the triceps, and on the outer side of the limb it
pierces the external intermuscular septum and appears in the
anterior compartment of the arm. Here it has already been
exposed. It lies deeply in the interval between the brachialis
anticus on the inside, and the supinator longus and extensor
carpi radialis longior on the outside. It ends in front of the
external condyle of the humerus by dividing into two terminal
branches, viz., the radial and the posterior interosseous. The
musculo-spiral nerve presents therefore very different relations
as it is traced from its origin to its termination: (i) between
the subscapularis, latissimus dorsi, teres major, and long head
of the triceps which support it behind, and the axillary and
brachial arteries which are placed in front of it; (2) between
the long and inner heads of the triceps; (3) in the musculo-
spiral groove between the bone and the outer head of the
triceps ; (4) in the interval between the brachialis anticus on
the inside, and the supinator longus and extensor carpi radialis
longior on the outside.
The branches which proceed from the musculo-spiral nerve
are partly muscular and partly cutaneous.
The cutaneous branches are three in number, and have
already been traced. They are — (1) the internal cutaneous,
which, as a rule, arises within the axilla, in common with
the branch which supplies the long or scapular head of the
triceps; (2) the upper external cutaneous, and (3) the lower
extei-nal cutaneous, which come off on the outer side of the
arm close to the outer margin of the external intermuscular
septum (p. 60).
The muscular branches go to the three heads of the triceps,
to the anconeus, to the brachialis anticus, to the supinator
longus, and to the extensor carpi radialis longior. The
branches to the three last muscles spring from the main trunk
after it has pierced the external intermuscular septum.
The branch to the inner head of the triceps is sometimes
termed the ulnar collateral nerve. It is a long slender
filament, which runs downwards to supply the lower fibres
of the inner head of the triceps, and it receives this name
from the close manner in which it is applied to the ulnar
nerve in the lower part of its course.
The bra?ich to the anconeus is also a long slender twig,
which enters the substance of the internal head of the triceps,
BACK OF THE ARM 81
and appears at first sight to terminate there, but, if traced
downwards, it will be found to end in the anconeus.
Superior Profunda Artery (arteria profunda brachii). —
This artery has been already observed to take origin from
the brachial trunk, immediately below the lower margin of
the teres major muscle. It accompanies the musculo-spiral
nerve, and its relations to the three heads of the triceps and
the musculo-spiral groove of the humerus are exactly the
same as those of the nerve. When it reaches the external
intermuscular septum, at the outer side of the arm, it ends
by dividing into two terminal branches— an anterior and a
posterior. The anterior and smaller branch accompanies the
musculo-spiral nerve through the septum, and follows it
downwards to the anterior aspect of the external condyle
of the humerus, where it anastomoses with the radial re-
current artery. The posterior larger branch proceeds down-
wards on the posterior surface of the external intermuscular
septum, and anastomoses on the back of the external con-
dyle of the humerus with the posterior interosseous recurrent
artery.
The branches which proceed from the superior profunda
artery are chiefly distributed to the three heads of the triceps
muscle. One twig runs upwards between the long and
outer heads of the muscle, and anastomoses with the
posterior circumflex artery. In this way, a link is established
between the axillary and brachial systems of branches.
Dissection. — The ulnar nerve, with the inferior profunda artery, and the
slender ulnar collateral nerve, can now be advantageously followed, as
they proceed downwards upon the posterior aspect of the internal inter-
muscular septum. They are covered by a thin layer of fleshy fibres be-
longing to the internal head of the triceps. The posterior branch of the
anastomotica magna, after it has pierced the internal septum, should also
be dissected out. As a rule, a transverse branch passes between this
vessel and the posterior terminal part of the superior profunda. It lies
upon the back of the humerus, immediately above the elbow-joint, and can
be exposed by dividing the triceps muscle a short distance above the
olecranon. At the same time the fleshy fibres of the internal head of the
triceps, which are inserted into the posterior ligament of the joint, and
constitute the suhanconeus muscle, should be examined. Lastly, raise the
lower piece of the triceps from the elbow-joint, and look for a small bursa
between the deep surface of the triceps tendon and the upper aspect of the
olecranon.
VOL. I — 6
82
THE UPPER LIMB
SHOULDER-JOINT.
Before proceeding to the dissection of the forearm it
is advisable to study the shoulder-joint (articulatio humeri),
because if this is deferred too long the ligaments are apt to
become dry.
In no joint in the body is the movement so free, and so varied in its
character, as in the shoulder-joint. This is rendered necessary by the
many functions which are performed by the upper limb. Freedom of
Capsule of joint
Supraspinatus
g- — Scapula
Subscapular!*
Serratus magnus
Fold of capsule
of
Posterior circumflex
artery and circumflex
nerve
Teres major
Musculo-spiral nerve
Latissimus dorsi
Fig. 35. — Coronal or vertical transverse section through the Left
Shoulder-joint. (Viewed from behind. )
motion is provided for in two ways — ( 1 ) by the large size of the head of
the humerus, in comparison with the small dimensions and shallow character
of the glenoid fossa — the socket in which it moves ; (2) by the great laxity
of the ligamentous structures which connect the humerus with the scapula.
These provisions for allowing an extensive range of movement at this
articulation might, at first sight, lead one to doubt the security of the joint.
Its strength certainly does not lie in the adaptation of the bony surfaces to
one another, nor in the power of its ligaments. It lies — (1) in the intimate
manner in which the scapular muscles are arranged around it ; (2) in the
overhanging coraco-acromial arch which forms, as it were, a secondary
SHOULDER-JOINT 83
socket for the head of the humerus, and effectually prevents any displace-
ment in an upward direction ; and (3) in atmospheric pressure, which
exercises a powerful influence in keeping the opposed surfaces in contact
with each other.
From all points of view, except over a small area below, the loose,
ligamentous capsule which envelops the shoulder -joint is supported by
muscles, the tendons of which are more or less intimately connected with
it. Above, it is covered by the supraspinatus ; behind, the infraspinatus
and teres minor are applied to it ; in front is the subscapularis. Below,
the capsule is to a certain extent unsupported by muscles, and here it is
prolonged downwards, in the form of a fold, in the ordinary easy dependent
position of the limb (Fig. 35). When, however, the arm is abducted, this
fold is obliterated, and the head of the bone rests upon the inferior part
of the capsule, which now receives partial support from two muscles which
are stretched under it, viz., the long head of the triceps and the teres major.
Still, this must be regarded as the weakest part of the joint, and consequently
dislocation of the head of the humerus, downwards into the axilla through
the inferior part of the capsule, is an occurrence of considerable frequency.
Dissection. — Detach the axillary vessels and brachial nerves from the
coracoid process to which they have been tied, and throw them downwards.
Then proceed to remove the muscles. Divide the conjoined origin of the
short head of the biceps and the coraco-brachialis close to the coracoid
process, the teres major about its middle, and the long head of the triceps
about an inch or two below its origin, and turn them aside. Next deal
with the muscles more immediately in relation to the joint, viz., the supra-
spinatus, the infraspinatus, the teres minor, and the subscapularis. These
must be removed with great care and deliberation, because their tendons
are closely connected with the subjacent ligamentous capsule. They are
not incorporated with the capsule, however, although at first sight they
appear to be so, and thus they can be dissected from it. In the case of the
subscapularis a protrusion of the synovial membrane, forming a bursa, will
be found near its upper border, close to the root of the coracoid process.
The capsule of the shoulder-joint may now be cleaned, and its attachments
defined.
The ligaments in connection with the shoulder- joint
are : —
1. The capsular ligament.
2. The coraco-humeral.
3. The gleno-humeral.
4. The glenoid.
Capsular Ligament (capsula articularis). — The capsule of
the shoulder-joint is a dense and strong ligamentous structure,
which envelops the articulation on all sides. It is attached to
the scapula around the glenoid cavity, but only above is it
directly fixed to the bone. Elsewhere it springs from the
fibrous ring or glenoid ligament, which serves to deepen the
articular cavity ; indeed, in its lower part, it appears to be
nearly continuous with the border of the glenoid ligament.
Externally it is fixed to the outer part of the anatomical
neck of the humerus. The width of the capsule is not
uniform throughout. It will be noticed to expand as it
1— 6 a
84
THE UPPER LIMB
passes over the enclosed head of the humerus, and to con-
tract as it reaches its scapular and humeral attachments.
The great laxity of the capsule of the shoulder-joint will
now be apparent. When the muscles are removed, and air
is admitted into the joint, the bony surfaces fall away from
each other — the head of the humerus sinking downwards,
when the part is held by the scapula, to the extent of an inch.
The capsule of the shoulder-joint is not complete upon all
aspects. Its continuity is interrupted by two, and sometimes
Coraco-acromial
ligament
Acromion process
Coracoid process
Communication
between joint-
cavity and sub-
scapular bursa
Capsule of joint
Coraco-humeral
ligament
Subscapularis
muscle
Long
tendon
of biceps
Fig. 36. — Shoulder-joint as seen from the front.
three, apertures. The largest of these is an opening of some
size, which is placed upon its inner or anterior aspect, near
the root of the coracoid process. Through this aperture an
extensive protrusion of the synovial membrane takes place in
the form of a synovial bursa, which, from its position under
the upper part of the subscapularis muscle, receives the name
of the bursa subscapularis. It is important to note the position
and character of this opening, seeing that in some cases the
head of the bone may be driven through it in dislocation of
the joint. The second aperture is smaller and more distinctly
defined. It is placed between the two tuberosities of the
SHOULDER-JOINT 85
humerus, at the upper part of the bicipital groove, and it is
through this that the long tendinous head of the biceps
gains admission to the interior of the capsule. The synovial
membrane also protrudes from this opening, and lines the
bicipital groove as low as the insertion of the pectoralis major.
It is not often that the third openi?ig is seen. It is situated,
when present, on the outer or posterior aspect of the capsule,
and allows a pocket of synovial membrane to bulge out in
the form of a bursa under the infraspinatus muscle.
At certain points the capsule of the shoulder-joint is
specially thickened by the addition of fibres, which pass from
the scapula to the humerus. Two of these thickened portions
receive the names of the coraco-humeral and the gleno-hii7?ieral
ligaments. A third is placed on the inferior aspect of the
capsule, where it is not supported by muscles, viz., between
the long head of the triceps and the subscapularis muscles.
It is against this thickened portion of the capsule that the
head of the humerus rests when the arm is abducted from
the side, and it is sometimes spoken of as the ififerior accessory
ligament, or inferior gleno-humeral ligament.
Coraco-humeral Ligament (ligamentum coraco-humerale).
— This is placed upon the upper aspect of the joint. It
is a broad band of great strength, which is more or less
completely incorporated with the capsule. Above, it is fixed
to the root and outer border of the coracoid process of the
scapula, and it passes from this obliquely downwards and
outwards, to gain attachment to the two tuberosities of the
humerus. It forms a strong arch over the upper part of
the bicipital groove, under which the tendon of the biceps
passes.
Gleno-humeral Ligament. — This ligament can only be seen
when the joint is opened. The dissector should therefore, at this
stage, remove the posterior part of the capsule, and, drawing
the bones well apart from each other, look forwards into the
cavity. The tendon of the biceps will be observed arching
over the head of the humerus, to reach its insertion on the
upper aspect of the glenoid cavity. Immediately internal to
this, and parallel to it, will be noticed a ridge on the inner
aspect of the capsule projecting into the joint. This band is
the gleno-humeral ligament (of Flood). It is inserted into
a faintly-marked pit on the anatomical neck of the humerus,
close to the upper end of the bicipital groove.
86
THE UPPER LIMB
As already noted, the thickened band in the inferior part of the capsule
is sometimes called the inferior gleno- humeral ligament. Another thicken-
ing of the front wall of the capsule between this and the gleno-humeral
ligament proper has received the name of the middle gleno - humeral
ligament.
Dissection. — Complete the division of the capsular ligament, and draw-
ing the tendon of the biceps through the intertubercular aperture in the
capsule, separate the two bones from each other.
Glenoid Ligament (labrum glenoidale). — The glenoid
ligament is the dense fibro- cartilaginous band which sur-
Conoid ligament
Trapezoid ligament
Coraco-acromial
ligament
Coracoid process
Superior gleno-
humeral ligament
Bursal opening
in capsule
Inferior gleno-
humeral ligament
Glenoid cavity
Acromio-
clavicular
isament
X Long tendon
of biceps
Capsule of
shoulder-
joint
s (ilenoid
ligament
Fig 37. — Capsular Ligament cut across and Humerus removed.
rounds the margin of the glenoid cavity of the scapula, and
is attached to its rim. It deepens, and at the same time
serves to extend, the articular socket of the scapula. The
intimate connection which it presents with the capsule of the
joint can now be studied. Two tendons are also closely
associated with it, viz., the long head of the triceps below,
and the long head of the biceps above.
Long Head of the Biceps. — The long tendon which
receives this name is an important factor in the construe-
SHOULDER-JOINT 87
tion of the shoulder- joint. Entering the capsule through
the opening between the two tuberosities of the humerus,
it is prolonged over the head of the bone to the top of the
glenoid cavity. Its origin should now be examined. It
divides into three portions, viz., a large intermediate part, which
obtains direct attachment to the scapula, and two smaller
lateral parts, which diverge from each other and blend with
the glenoid ligament. The long head of the biceps, by its
position within the capsule, and in the deep groove between
the tuberosities of the humerus, serves to keep the head of
the bone in place, and to steady it in the various movements
at the shoulder-joint.
Synovial Membrane. — The synovial membrane lines the
interior of the capsular ligament, and is reflected from it upon
the anatomical neck of the humerus as far as the articular
margin of the head of the bone. The bursal protrusion of
the synovial membrane {bursa subscapularis) under the tendon
of the subscapularis muscle has already been noticed. The
tendon of the biceps, as it traverses the joint, is enveloped in a
tubular sheath of the membrane, which bulges out through
the opening of the capsule in the form of a bursa, which lines
the bicipital groove, and receives the name of bursa inter-
tubercularis.
Articular Surfaces. — The smooth, glistening articular
cartilage, which coats the head of the humerus, is thickest
in the centre, and thins as it passes towards the edges. In
the case of the glenoid cavity the reverse of this will be
noticed. The cartilaginous coating is thinnest in the centre,
and becomes thicker as it is traced towards the circumference.
Movements at the Shoulder- joint. — The shoulder is a ball-and-socket
joint, and consequently movement in every direction is permitted, viz. — (1)
flexion, or forward movement ; (2) extension, or backward movement
(checked in its extent by the coraco-humeral ligament) ; (3) abduction, or
outward movement (checked by the coraco-acromial arch) ; (4) adductii u,
or inward movement (limited by the coraco-humeral ligament). In
addition to these different forms of angular movement, rotation to the
extent of a quarter of a circle and circumduction are permitted.
The muscles chiefly concerned in producing these movements are : —
flexion — the pectoralis major and the anterior part of the deltoid ; extension
— latissimus dorsi, posterior part of the deltoid, and the teres major ;
abduction — the deltoid and supraspinatus; adduction — pectoralis major,
coraco-brachialis, teres major, and latissimus dorsi ; rotation inwards —
subscapularis, pectoralis major, latissimus dorsi, teres major ; rotation
ouhvards — supraspinatus, infraspinatus, and teres minor ; circumduction is
produced by the action of different combinations of these muscles.
88 THE UPPER LIMB
FOREARM AND HAND.
Dissection.- — The skin has already been removed from the front and
back of the forearm. It should now be raised from the dorsum of the
hand by making incisions along the radial and ulnar borders. This is
done in order that the superficial structures in this region may be examined
in connection with those of the forearm.
Superficial Veins. — On the dorsum of the hand a plexus
of superficial veins will be seen. In defining this, care must
be taken of the fine cutaneous twigs from the radial nerve and
the dorsal branch of the ulnar nerve. From the outer part of
the venous plexus the large radial vein takes origin, whilst
from its inner part springs the posterior ulnar vein. Both of
these vessels have already been traced along the forearm to
their terminations. While still upon the dorsum of the hand
each communicates with the deep veins in the palm of the
hand.
Cutaneous Nerves. — Several cutaneous nerves have already
been traced to the integument of the forearm, viz., the
anterior and posterior branches of the internal cutaneous
nerve to the inner aspect, and the cutaneous part of the
musculo-cutaneous and lower external cutaneous branch of
the musculo-spiral upon the outer aspect of the limb. Some
additional twigs make their appearance by piercing the fascia
in the lower third of the forearm.
i. The palmar cutaneous branch of the
ulnar nerve,
2. The palmar cutaneous branch of the ,, f
r ,. -on the front aspect,
median nerve,
3. The palmar cutaneous branch of the
radial nerve,
1. The dorsal branch of the ulnar \
nerve, - on the dorsal aspect.
2. The radial nerve, j
Palmar Cutaneous Branches. — These are small twigs which
supply the skin of the palm. The twig from the ulnar nerve
takes origin about the middle of the forearm, but it does not
at once pierce the deep fascia. It proceeds downwards on
the ulnar artery, and becomes superficial immediately above
the annular ligament, and close to the outer side of the
insertion of the flexor carpi ulnaris tendon into the pisiform
bone. It is here, therefore, that it must be sought for (Fig.
24, p- 59)-
FOREARM AND HAND 89
•
The palmar cuta?ieous branch of the ?7iedian nerve appears
through the deep fascia in the interval between the tendons
of the flexor carpi radialis and the palmaris longus muscles,
immediately above the wrist. It is continued downwards into
the palm (Fig. 24, p. 59).
The palmar branch of the radial nerve runs close to the
outer border of the lower part of the forearm. It does not
spring from the trunk of the radial nerve, but from that branch
of it which goes to the outer margin of the thumb. It is
joined by a twig from the musculo-cutaneous nerve, and
proceeds downwards in front of the tendon of the extensor
ossis metacarpi pollicis, to end in the skin covering the ball
of the thumb (Fig. 24, p. 59).
Dissection. — In tracing the nerves which appear on the back of the
limb, it will be necessary to remove the skin from the dorsal aspect of
the thumb and fingers. The great flap of skin which is still attached at
the roots of the fingers may be detached, and an incision can then be made
along the middle of the dorsal aspect of each digit. The skin should be
carefully raised from each finger in two flaps and thrown outwards and
inwards.
Dorsal Cutaneous Branches. — The dorsal branch of the
ulnar nerve winds round the inner margin of the wrist to reach
the dorsum of the hand. It will be found immediately below
the prominence formed by the lower end of the ulna, and it
at once divides into three main terminal branches. Of these,
the innermost runs along the ulnar margin of the dorsum of
the hand, and is continued onwards along the inner margin
of the little finger. The second branch proceeds towards the
cleft between the little finger and the ring finger, and divides
into two twigs which supply the contiguous sides of these
digits. The third branch joins a twig from the radial, and
the nerve thus formed runs towards the interval between
the ring finger and the middle finger, and divides to supply
their adjacent margins. Each of these three main branches
gives several minute filaments to the integument on the
dorsum of the hand (Fig. 25, p. 61).
The radial nerve will be found winding round the outer
margin of the forearm, about two inches above the extremity
of the styloid process of the radius. It at once gives off a
long twig which proceeds along the radial margin of the hand
and thumb. A little farther on the radial nerve breaks up
into four terminal branches, which are distributed as follows :
9o THE UPPER LIMB
the first supplies the ulnar side of the thumb ; the second goes
to the radial side of the index finger ; the third divides to
supply the adjacent sides of the index and middle fingers ;
whilst the fourth joins with a twig from the dorsal branch of
the ulnar (as already described) to supply the contiguous
margins of the middle and ring fingers.
It should be noted that, except in the case of the thumb
and little finger, the dorsal collateral nerves do not reach the
extremities of the digits. The skin on the back of the second
and third phalanges of the digits is chiefly supplied by twigs,
which proceed backwards from the palmar collateral branches
from the median and ulnar nerves. As already stated, it is
from the branch of the radial, which goes to the outer side
of the thumb, that the radial palmar cutaneous nerve arises.
Numerous fine filaments are given to the skin on the
dorsum of the hand, and a certain amount of crossing of the
adjacent ulnar and radial twigs takes place in this locality ;
in other words, twigs from the one nerve invade the territory
which is occupied by the other nerve.
Deep Fascia. — The deep fascia which envelops the fore-
arm should now be cleaned by removing the subcutaneous
adipose tissue. It is an aponeurosis of great strength and
density. More particularly is this the case on the posterior
aspect of the limb, and also in the lower third of the forearm,
where the fleshy bellies of the subjacent muscles give place
to the tendons. In its upper part it receives an accession of
fibres from the tendon of the biceps in the form of the
bicipital or semilunar fascia. Some fibres are also given to
it by the tendon of the triceps. Near the elbow it serves as
a surface of origin for the numerous muscles which spring
from the condyles of the humerus, and from its deep aspect
dense septa pass between the fleshy bellies. These partitions
are indicated on the surface by a series of white lines. At
the wrist it becomes continuous in front with the anterior
annular ligament, whilst behind it forms an obliquely placed,
thickened band, the posterior annular ligament. On the
dorsum of the hand the deep fascia is thin.
Front and Inner Border of the Forearm.
In this dissection the following structures will be brought
under the notice of the student : —
FOREARM AND HAND 91
1. The radial and ulnar arteries and their branches.
2. The median and ulnar nerves and their branches.
3. The posterior interosseous and the radial nerves.
4. The group of pronator and flexor muscles.
Dissection. — With the exception of the palmar cutaneous nerves, the
superficial veins and nerves on the front of the forearm may now be turned
aside. The deep fascia should also be removed, and on dissecting it
inwards round the ulnar border of the forearm it will be found to be firmly
attached to the posterior border of the ulna. Near the elbow, as already
stated, it gives origin by its deep surface to the group of muscles which
spring from the internal condyle of the humerus. Where this is the case,
it should be left in situ. Attempts to dissect it off will only result in
laceration of the surface of the subjacent fleshy bellies. The radial artery
should be followed out before the muscles are much disturbed, and at the
same time the various muscles which lie upon the anterior surface of the
radius, and upon which the vessel rests, should be cleaned.
Radial Artery (arteria radialis). — The radial artery is the
smaller of the two terminal branches of the brachial artery,
but the direction which it takes gives it the appearance of
being the continuation of the parent trunk into the forearm.
It takes origin in the antecubital fossa opposite the neck of
the radius, and it proceeds downwards along the outer side
of the front of the limb until it reaches the lower end of the
bone. Here it turns round the outer aspect of the wrist and
leaves the present dissection. At first it lies between the
pronator radii teres and the supinator longus, and is over-
lapped to some extent on the outer side by the fleshy belly of
the latter muscle (Fig. 38). Lower down it is placed between
the supinator longus on the outside and the flexor carpi
radialis upon the inner side, and this position it maintains as
far as the wrist. Where these muscles are fleshy the artery
lies at some depth from the surface ; but when the tendons
make their appearance it assumes a superficial position, and
is merely covered by the integument and fasciae. Through-
out its wrhole length it is closely accompanied by the vence
comites, and the radial nerve lies along its outer side in the
middle third of the forearm. Above this, the nerve is
separated from the vessel by a slight interval ; whilst below,
the nerve leaves the artery by turning round the outer margin
of the forearm under cover of the supinator longus.
Posteriorly the radial artery is supported by the muscles
which clothe and find attachment to the front of the radius.
At its origin it rests upon the tendon of the biceps ; next it
lies in front of the supinator brevis, with some adipose tissue
intervening ; from this downwards it is in contact with the
92 THE UPPER LIMB
pronator radii teres, the thin radial head of the flexor sublimis,
the flexor longus pollicis, the pronator quadratus, and lastly,
the lower end of the radius.
The radial artery is usually selected for the determination of the pulse.
By placing the tips of the fingers upon the lower part of the forearm, in
the interval between the tendons of the supinator longus and flexor carpi
radialis, the pulsations of the vessel in the living person can readily be felt.
Branches of the Radial Artery- — In the forearm the radial
artery gives off the following branches, viz. : —
i. The radial recurrent.
2. The superficialis voke.
3. The anterior radial carpal.
4. Muscular.
The muscular branches (rami musculares) are very numerous,
and proceed from the radial artery at irregular points through-
out its whole course in the forearm.
The radial recurrent artery (arteria recurrens radialis) is a
branch of some size. It takes origin close to the com-
mencement of the radial artery, and in the first instance runs
outwards between the supinator longus and the supinator
brevis. Here it comes into relation with branches coming
from the musculo-spiral nerve, and gives off several twigs for
the supply of the muscles arising from the external condyle
of the humerus. Somewhat reduced in size, it now turns
upwards in the interval between the supinator longus and
brachialis anticus, and ends in front of the external condyle
of the humerus by anastomosing with the anterior terminal
branch of the superior profunda artery.
The superficialis volcz artery (ramus volaris superficialis) is a
small, variable branch, which arises a short distance above
the wrist, and runs downwards to end in the muscles of the
ball of the thumb. Sometimes, however, it attains a larger
size and a special importance, from its being continued into
the palm to complete the superficial palmar arch on the
outer side.
The anterior radial carpal (ramus carpeus volaris) is a
minute twig which springs from the radial at the lower border
of the pronator quadratus muscle. It runs inwards under
cover of the flexor tendons, and joins the corresponding
branch of the ulnar artery to form the anterior carpal arch.
Radial and Posterior Interosseous Nerves. — The musculo-
spiral nerve has already been observed to end in front of the
FOREARM AND HAXD
93
elbow, under cover of the supinator longus muscle, in its two
terminal branches, the radial and the posterior interosseous.
These nerves may now be studied in so far as they lie on the
front of the forearm. The posterior interosseous nerve (nervus
interosseus dorsalis) soon disappears from view by passing
backwards on the outer side of the radius through the fibres
of the supinator brevis muscle.
The radial nerve (nervus cutaneus antibrachii dorsalis) pro-
ceeds downwards under cover of the fleshy belly of the
supinator longus. In the middle third of the forearm it lies
Ulnar vessels and
median nerve
Radial artery
and nerve
Posterior inter-
osseous nerve
Extensor minimi
digiti
Ulnar nerve
Anconeus
Fig. 38. — Transverse section through the Upper Third of the Left Forearm.
along the outer side of the radial artery, and then leaves
it by winding round the outer margin of the limb, under
cover of the tendon of the supinator longus. It has been
traced in its farther course (p. 89). The radial is a purely
cutaneous nerve, and gives off no branches until it gains the
dorsal aspect of the lower end of the forearm.
Muscles. — The muscles on the front and inner border of
the forearm are arranged in a superficial and a deep group.
They comprise the flexors of the wrist and fingers, and also
the pronators. In the superficial group we find the pronator
radii teres, the flexor carpi radialis, the palmaris longus, the
flexor sublimis digitorum, and the flexor carpi ulnaris, in that
94 THE UPPER LIMB
order from without inwards. The fleshy belly of the flexor
sublimis only partially comes to the surface ; the chief bulk of
it is placed upon a deeper plane than the others. The deep
group is composed of three muscles, placed in contact with the
bones and interosseous membrane of the forearm, viz., the
flexor profundus digitorum in relation to the ulna, the flexor
longus pollicis in relation to the radius, and the pronator
quadratus closely applied to the lower ends of both bones.
Dissection. — The superficial group of muscles should now be dissected.
The supinator longus, which lies along the outer side of the forearm, may
be cleaned at the same time. In the lower part of the forearm the
dissector will observe that the flexor tendons are enveloped by a loose
bursal sac as they pass into the palm, under cover of the anterior annular
ligament. A good view of this may be obtained by pulling the tendons
upwards. If possible, the sac should be retained uninjured, in order that
its full extent may be studied when the palm of the hand is opened up.
At this stage it is also well to define the anterior annular ligament which
bridges across the front of the carpus. The tendon of the palmaris longus
passes in front of it, whilst close to the pisiform bone the uinar artery and
nerve are placed upon its anterior surface, and give the dissector the key
to its depth. This vessel, with its accompanying nerve, are bound down
to the ligament by a slip of fascia, which passes over them from the
pisiform bone, and which the student is very apt to mistake for the annular
ligament itself. This slip of fascia should not be disturbed in the
meantime.
Common Origin of the Superficial Muscles. — The five
muscles which constitute the superficial group are very closely
associated with each other at the elbow — indeed, they may
be said to arise by a common origin from the front of the
internal condyle of the humerus. In addition to this they
all derive fibres from the investing deep fascia of the limb near
the elbow, and the strong fibrous septa which pass into the
forearm from the deep surface of this in the intervals between
them. The pronator radii teres, the flexor sublimis, and the
flexor carpi ulnaris, have likewise additional heads of origin.
Pronator Radii Teres (musculus pronator teres). — This
muscle crosses obliquely the upper half of the front of the
forearm. It arises by two heads, viz., a humeral and a coronoid.
The humeral head constitutes the chief bulk of the muscle,
and it springs from the upper part of the internal condyle of
the humerus, and also slightly by fleshy fibres from the lower
part of the internal supracondyloid ridge. The fascia cover-
ing it and the fibrous septum on its inner side also contribute
fibres. The coronoid head is placed deeply, and it may be
recognised from the fact that it intervenes between the
FOREARM AND HAND 95
median nerve and the ulnar artery. To bring it into view the
superficial humeral head must be drawn well inwards. The
coronoid head is very variable in size. As a rule, it is a
small fleshy slip, but sometimes it is chiefly fibrous. It
arises from the inner aspect of the coronoid process of the
ulna (Fig. 40, p. 101), and soon joins the deep surface of the
humeral head. The muscle thus formed is carried obliquely
downwards and outwards, and ends in a tendon which gains
insertion into a rough impression upon the middle of the
outer surface of the radius (Fig. 40, p. 101). This attachment
is placed on the summit of the chief curve of the radius,
an arrangement which enables the muscle to exercise its
pronating action at a great advantage. Close to its inser-
tion the pronator radii teres is crossed by the radial artery
and is covered by the supinator longus muscle. It is supplied
by the ?nedian nerve.
Flexor Carpi Radialis. — The flexor carpi radialis arises
from the common tendon, from the fascia of the forearm
and the fibrous septa which intervene between it and the
adjacent muscles. Its fleshy belly gives place a short distance
below the middle of the forearm to a long flattened tendon,
which at the wrist traverses the groove on the front of the
trapezium in a special compartment of the anterior annular
ligament. It is inserted into the palmar aspect of the base
of the metacarpal bone of the index, and slightly also into
the base of the metacarpal bone of the middle finger. Its
relations to the annular ligament, and also its attachment to
the metacarpus, will be exposed and studied at a later stage
of the dissection. It is supplied by the median nerve.
Palmaris Longus. — This is a long slender muscle, which is
not always present. It springs from the common origin, the
aponeurotic investment of the forearm and the fibrous septum
on either side of it. Its tendon pierces the deep fascia
immediately above the wrist, and then proceeds downwards
in front of the annular ligament to join the strong central
portion of the palmar fascia of the hand. Very frequently
it gives a slip to the abductor pollicis muscle. It is supplied
by the median ?ierve.
Flexor Carpi Ulnaris. — This muscle arises by two heads.
One of these is incorporated with the common origin from
the humeral condyle ; the other springs from the inner aspect
of the olecranon process of the ulna, and likewise by an
96 THE UPPER LIMB
aponeurotic attachment from the posterior border of the same
Flexor
Palmans longus — j \ '^, %
■ ■ Ik
Flexor carpi radialis .' ,' ; "
Radial nerve lw~/'
Radial head of flexor 1 i[ij
sublimis
Median nerve
A. comes n. mediani
Radial artery
Radial head of flexor
Triceps
Ulnar nerve
-^» -': Olecranon
li_Fibrous arch between heads
mi\ of flexor carpi nlnaris
Ulnar nerve
Branch to flexor profundi i-.
iigitorum
iranch to flexor carpi
nlnaris
M. _Flexor profundus
digitorum
s. v™ Ulnar ner\'e
jt&T \ Ulnar artery
1 n
and nerve
longus polhcis ^yyA'1
Dorsal branch of ulnar nerve
Flexor profundus digitorum
Pronator quadratus
Extensor ossis meta
carpi pollici
Fig. 39. — Dissection of the front of the Forearm ; the superficial muscles are
cut short and turned aside and the deeper parts are still further displayed
by separating the flexor sublimis from the flexor carpi ulnaris along the
line of the intermuscular septum which intervenes between them.
bone in its upper two-thirds. Fibres are also derived from the
investing fascia and the intermuscular septum on its outer
FOREARM AND HAND 97
side. The two heads of origin of the flexor carpi ulnaris
bridge across the interval between the internal condyle of the
humerus and the olecranon process, and between them the
ulnar nerve is prolonged downwards into the forearm. The
tendon appears upon the anterior border of the muscle, and
is inserted into the pisiform bone. The flexor carpi ulnaris
is supplied by the ulnar nerve.
Flexor Sublimis Digitorum. — The flexor sublimis receives
this name from its being placed upon the superficial aspect
of the flexor profundus. For the most part it lies deeper
than the other superficial muscles (Fig. 38). It is a powerful
muscle which arises from the internal condyle of the
humerus by the common tendon, but it also takes origin
from the internal lateral ligament of the elbow- joint, from
the inner margin of the coronoid process of the ulna, the
front of the radius (Fig. 40, p. 101), and the fascial inter-
muscular septa in relation to it. The radial head of
origin is a thin fleshy stratum which is attached to the
oblique line of the radius and the anterior border of that
bone for a variable distance below the insertion of the
pronator radii teres. Four tendons issue from the fleshy
mass. These enter the palm by passing under cover of the
anterior annular ligament, and go to the four inner digits.
Their insertions will be seen later on, but in the meantime
note that at the wrist and for a short distance above it they
are enveloped by the bursal sac previously mentioned, and
also that as they pass behind the annular ligament they lie
in pairs — the tendons to the ring and middle fingers being
placed in front of those for the index and little fingers. The
flexor sublimis digitorum is supplied by the median nerve.
Dissection. — The ulnar artery and at the same time the ulnar and
median nerves should be followed in their course through the forearm.
The artery in the upper part of its course lies very deeply, but its relations
can be fully studied and its branches traced by simply slitting up the
intermuscular septum between the flexor sublimis digitorum and the flexor
carpi ulnaris.
Ulnar Artery (arteria ulnaris). — This is the larger of the
two terminal branches of the brachial trunk, and it takes
origin in the antecubital fossa opposite the neck of the radius.
At first it inclines obliquely downwards and inwards, and
having gained the front of the ulnar side of the forearm, it
proceeds vertically downwards to the wrist. Here it enters
vol. 1 — 7
98 THE UPPER LIMB
the palm by passing in front of the anterior annular liga-
ment. In the upper oblique portion of its course the vessel
is deeply placed, and is crossed by both heads of the
pronator radii teres, the flexor carpi radialis, the palmaris
longus, and the flexor sublimis digitorum. In its lower
vertical part it is overlapped on the inner side by the flexor
carpi ulnaris, but a short distance above the wrist it becomes
superficial, and lies in the interval between the tendon of the
flexor carpi ulnaris on the inside and the tendons of the
flexor sublimis on the outside. On the annular ligament it is
placed close to the outer side of the pisiform bone, and is
covered by a strong slip of fascia, which passes from that bone
to the front of the ligament. Throughout its entire course it
is accompanied by two vena comites. It likewise presents
relationships with the median and ulnar nerves. The median
nerve, which lies upon its inner side at its origin, soon crosses
it, but as it does so it is separated from the artery by the
deep head of the pronator radii teres. The ulnar nerve in the
upper third of the forearm is separated from the vessel by a
wide interval, but in the lower two-thirds of the forearm it
closely accompanies the artery, and lies on its inner side.
In the antecubital fossa the ulnar artery rests upon the
brachialis anticus ; beyond this it is in contact behind with
the flexor, profundus digitorum ; whilst at the wrist the artery
lies upon the anterior surface of the anterior annular ligament.
Branches of the Ulnar Artery. — In the forearm the ulnar
artery gives off the following branches : —
1. Anterior ulnar recurrent.
2. Posterior ulnar recurrent.
~x. Common interosseous.
4. Anterior ulnar carpal.
5. Posterior ulnar carpal.
6. Muscular twigs.
The muscular twigs are of small size, and come off at
variable points for the supply of the neighbouring muscles.
The ajiterior ulnar recurrent artery is the smaller of the two
recurrent branches. • It runs upwards in front of the internal
condyle of the humerus, in the interval between the pro-
nator radii teres and the brachialis anticus muscles, and
it anastomoses with the anterior terminal branch of the ana-
stomotica magna.
The posterior ulnar recurrent passes inwards under cover of
the flexor sublimis digitorum, and then turns upwards between
the two heads of origin of the flexor carpi ulnaris to gain the
FOREARM AND HAND 99
interval between the internal condyle of the humerus and
the olecranon process on the posterior aspect of the limb.
Here it comes into contact with the ulnar nerve, and
anastomoses with the posterior terminal branch of the
anastomotica magna and with the inferior profunda artery.
It is not uncommon to find the two recurrent arteries
arising from the ulnar trunk by a short common stem.
The common interosseous artery (arteria interossea com-
munis) is a short, wide trunk, which takes origin immediately
below the recurrent branches, about an inch or so below the
commencement of the ulnar artery. It proceeds backwards,
and at the upper margin of the interosseous membrane it
divides into two terminal branches, viz., the anterior and the
posterior interosseous arteries.
The ulnar carpal branches are two small arteries, which
partially encircle the wrist. The anterior ulnar carpal (ramus
carpeus volaris) runs outwards, under cover of the tendons of
the flexor profundus digitorum, and anastomoses with the
anterior radial carpal artery. From the arch thus formed
small twigs are given to the front aspect of the carpal bones
and joints. The posterior ulnar carpal artery (ramus carpeus
dorsalis) gains the dorsal aspect of the carpus by winding round
the ulnar margin of the limb immediately above the pisiform
bone, and under cover of the tendon of the flexor carpi ulnaris.
Ulnar Nerve (nervus ulnaris). — The ulnar nerve, which
was traced in the dissection of the arm as far as the interval
between the olecranon and internal condyle of the humerus,
enters the forearm between the two heads of the flexor carpi
ulnaris. It proceeds downwards upon the flexor profundus
digitorum, and under cover of the flexor carpi ulnaris along
the front of the ulnar side of the forearm. Close to the
wrist it becomes superficial upon the outer side of the tendon
of the flexor carpi ulnaris, and it reaches the palm by passing
in front of the anterior annular ligament. In the upper third
of the forearm the ulnar nerve is separated from the ulnar
artery by an interval, but below this it is closely applied to
the inner side of the vessel.
In the forearm the ulnar nerve gives off: —
1. Articular branches to the elbow-joint.
2. Muscular branches, |to thef flf ?r f^'1 ulnafris f nd the inner
' ^ part of the nexor profundus.
„ /--> * 1 l. ( palmar cutaneous.
3. Cutaneous branches, < K ,
J ' v. dorsal cutaneous.
1— la
ioo THE UPPER LIMB
The articular filaments come from the ulnar nerve as it lies
in the interval between the olecranon and internal condyle
of the humerus.
The muscular branches are given off high up in the fore-
arm, and supply the flexor carpi ulnaris and the inner part of
the flexor profundus digitorum.
The ulnar palmar cutaiieous branch is a minute twig, which
has already been seen piercing the fascia of the forearm
immediately above the annular ligament. It arises about the
middle of the forearm and proceeds downwards upon the
ulnar artery, to the coats of which it gives fine filaments.
The ulnar dorsal cutaneous branch is a nerve of some size
which springs from the ulnar trunk about two and a half or
three inches above the wrist. It winds round the ulnar
margin of the forearm under cover of the flexor carpi ulnaris,
and reaches the dorsum of the hand immediately below the
prominence formed by the lower end of the ulna. From
this point onwards it has been traced in the superficial dissec-
tion (p. 89).
Median Nerve (nervus medianus). — As its name implies,
the median nerve passes down the middle of the forearm ;
and to obtain an unbroken view of it, it is necessary to
reflect the condylar head of the pronator radii teres and the
radial head of the flexor sublimis digitorum.
In the upper part of the forearm the median nerve lies in
the antecubital fossa upon the inner side of the ulnar artery.
It leaves this space by passing between the two heads of the
pronator radii teres, and as it does so it crosses the ulnar
artery, but is separated from the vessel by the coronoid or
deep head of the muscle. From this point the median nerve
is carried downwards between the flexor sublimis and the
flexor profundus digitorum. Near the wrist it becomes
superficial, and lies in the interval between the tendons of the
flexor sublimis on the inside and the flexor carpi radialis on the
outer side. Finally it leaves the forearm by passing behind
the anterior annular ligament of the wrist. A small artery, the
median branch of the anterior interosseous, accompanies the
median nerve. Sometimes this vessel attains a considerable size.
As the median nerve enters the forearm it gives off
numerous branches for the supply of muscles, and near the
wrist it supplies the median palmar cutaneous fierve, which has
already been dissected.
FOREARM AND HAND
101
The muscular branches
supply the pronator radii
teres, the flexor carpi radialis,
the palmaris longus, and the
flexor sublimis digitorum —
all the muscles of the super-
ficial group, therefore, with
the single exception of the
flexor carpi ulnaris.
It likewise supplies a long
slender twig — the anterior
interosseous — which goes to
the deep muscles on the
front of the forearm.
Deep Structures on the
front of the Forearm. — The
connections of the deep
muscles must now be studied,
and at the same time the
anterior interosseous artery
and nerve must be followed.
The flexor profundus is the
large muscle which clothes
the anterior and inner aspects
of the ulna; the flexor longus
pollicis is placed upon the
anterior surface of the radius ;
while the pronator quadratus
is a quadrate fleshy layer
closely applied to both bones
immediately above the wrist.
The artery and nerve pro-
ceed downwards in the in-
terval between the flexor
profundus and flexor longus
pollicis.
Flexor Profundus Digi-
torum.— The deep flexor of
the fingers springs from the
anterior and internal surfaces
of the ulna in its upper
three- fourths. It likewise derives
i—76
Flexor sublimis digitorum
Pronator radii tere
Brachialis amicus
Flexor longus pollk
Supinator
longus
FlG. 40.— Anterior aspect of Bones of
Forearm with Muscular Attachments
mapped out.
fibres from the anterior
io2 THE UPPER LIMB
surface of the interosseous membrane and the aponeurosis
by which the flexor carpi ulnaris takes origin from the
posterior border of the ulna. The fleshy mass gives place
to four tendons for the four inner digits, but only one of
these — that for the forefinger — becomes separate and distinct
in the forearm. They proceed downwards behind the
anterior annular ligament into the palm. The flexor pro-
fundus digitorum is supplied by the anterior interosseous branch
of the median and by the ulnar nei-ve.
Flexor Longus Pollicis. — The flexor longus pollicis arises
from the anterior surface of the radius over an area which
extends from the oblique line above to the upper border of
the pronator quadratus below. It also takes origin from the
adjacent part of the anterior surface of the interosseous mem-
brane. A rounded tendon issues from the fleshy belly, and
proceeds into the palm, under cover of the anterior annular
ligament.
In many cases the flexor longus pollicis will be observed
to have an additional slender head of origin, from the inner
side of the coronoid process of the ulna, or the internal
condyle of the humerus. The flexor longus pollicis is supplied
by the a?iterior interosseous nerve.
Pronator Quadratus. — This is a quadrate muscle which
takes origin from the anterior surface of the ulna in its lower
fourth, and is inserted into the front aspect of the lower end
of the radius. It is supplied by the anterior interosseous nerve.
Anterior Interosseous Artery (arteria interossea volaris).
— The anterior interosseous artery has been seen to arise
from the common interosseous trunk. It runs downwards
upon the front of the interosseous membrane, in the interval
between the flexor longus pollicis and the flexor profundus
digitorum. At the upper border of the pronator quadratus it
pierces the interosseous membrane, and gains the posterior
aspect of the limb.
It supplies muscular twigs to the three deep muscles with
which it is in contact. In addition to these it gives off the
following branches : —
i. Median.
2. Medullary.
3. Anterior communicating.
The median artery is a long delicate vessel, which accom-
panies the median nerve. The medullary arteries are two in
FOREARM AND HAND 103
number — one for the radius, the other for the ulna. They
enter the nutrient foramina of these bones. The anterior
communicating is a slender artery, which runs downwards,
behind the pronator quadratus, to join the anterior carpal
arch.
Anterior Interosseous Nerve (nervus interosseus volaris).
— This is a branch of the median, and accompanies the
artery of the same name. It does not follow it, however,
through the interosseous membrane, but is distributed entirely
upon the front of the limb. It is the nerve of supply for
the flexor longus pollicis, the outer part of the flexor pro-
fundus digitorum, and the pronator quadratus, whilst its
terminal filament proceeds downwards, behind the last-named
muscle, to help in the supply of the carpal joints.
The flexor profundus digitorum is therefore supplied by
two nerves, viz., the ulnar and the median. The precise
range of supply by each of these nerves is somewhat variable.
As a general rule the division of the muscle which belongs to
the index finger is supplied by the median and the part
belonging to the little finger by the ulnar ; whilst the portions
belonging to the middle and ring digits receive filaments from
both nerves.
Wrist and Palm.
In this dissection we meet with the following structures : —
1. Palmaris brevis and the palmar cutaneous nerves.
2. Palmar fascia.
3. Superficial palmar arch and its branches.
4. Median and ulnar nerves and their branches.
5. Anterior annular ligament, the flexor tendons, and the flexor
sheaths.
6. Lumbrical muscles.
7. Short muscles of the thumb and little finger.
8. Deep palmar arch and its branches.
9. Arteria princeps pollicis and arteria radialis indicis.
Surface Anatomy. — In the centre of the palm the depres-
sion, known as the " hollow of the hand," may be remarked.
Along the ulnar border of the palm this is bounded by a
rounded elevation, called the hypothenar eminence, which is
produced by the subjacent short, intrinsic muscles of the little
finger. The thenar eminence, or ball of the thumb, formed by
the short muscles of that digit, is the marked projection which
1— 7 c
104
THE UPPER LIMB
limits the palmar hollow above and on the outer side ; whilst
the transverse elevation above the roots of the fingers, which
corresponds to the metacarpophalangeal articulations, con-
Princeps pollicis
Branch to muscles
of thumb
Superficialis vols
Median nerve
Radial artery
Fig. 41. — Diagram of Nerves and Vessels of Hand in relation to Bones
and Skin Markings.
stitutes the lower boundary of the central palmar depression.
Two pronounced bony projections on the front of the wrist
cannot fail to attract attention when the hand is bent back-
wards. The more prominent of the two is situated at the
upper extremity of the thenar eminence, and is formed by
FOREARM AND HAND 105
the tubercle of the scaphoid bone and the vertical ridge on
the front of the trapezium ; the other is placed at the upper
end of the hypothenar eminence, and is somewhat obscured
by the soft parts attached to it. It is caused by the pisiform
bone, and when taken firmly between the finger and thumb
a slight degree of gliding movement can be communicated
to it. Traversing the thick integument of the palm, three
strongly marked furrows are apparent. One of these begins
at the elevation formed by the scaphoid and trapezium, and
curves downwards and outwards around the base of the
thenar eminence to the outer margin of the hand. A second
crosses the palm transversely. Commencing at the middle of
the outer border of the hand, where the first furrow ends, it
runs inwards, but, as a general rule, it fades away upon the
hypothenar eminence. The third furrow begins near the
cleft between the index and middle fingers, and proceeds
inwards with a gentle curve across the hypothenar eminence
to the inner margin of the hand. The transverse cutaneous
furrows at the roots of the fingers, and on the palmar aspects
of the interphalangeal joints, should also be noticed. The
furrows at the roots of the fingers are placed over the front
of the proximal phalanges very nearly one inch below the
metacarpo-phalangeal joints. The upper of the two furrows
in front of each of the proximal interphalangeal joints is
placed immediately over the articulation, whilst in the case
of the distal interphalangeal joints the single crease which is
usually present corresponds more or less closely to the
articulation. On the back of the hand the metacarpal bones
can be readily felt, whilst their distal extremities or heads
form the prominences known as the "knuckles."
Reflection of Skin. — In the first instance the skin should only be raised
from the palm. Two incisions are required — viz., (1) a vertical incision
along the middle line of the palm ; (2) a transverse cut across the roots of
the fingers from the ulnar to the radial margin of the hand. The skin is
tightly bound down to the subjacent deep fascia, and it must be raised with
care. More especially is it necessary to proceed with caution at the roots
of the fingers in order that some transverse fibres constituting a superficial
cutaneous ligament may be preserved. In reflecting the inner flap of
integument it is well not to lift it quite as far as the ulnar border of the
hand, because it is into this portion of skin that the palmaris brevis is
inserted.
Superficial Structures. — The superficial fascia over the
central part of the palm is dense and thin. The fat is
io6
THE UPPER LIMB
subdivided into small lobules by fibrous septa which bind
the skin to the subjacent palmar fascia. Towards the ulnar
Palmaris longus \ — Jit uMA
. \ 1 :v™
h lexor carpi ulnaris -
Ulnar artery
Anterior annular ligament
Pisiform bone
Palmaris longus /
Palmaris brevis
Abductor minimi d
Flexor brevis minimi
digiti
Palmar fascia
(central part)
4th lumbrical with
digital artery and
nerves
3rd lumbrical with
digital artery and
nerves
ransverse superficial
ligament
Flexor sublimis
I Supinator longus
i. — Flexor carpi radialis
BEL Radial artery
1
Median nerve
Extensor ossis metacarpi pollicis
Superficialis volae artery
Opponens pollicis
Abductor pollicis
Flexor brevis pollicis
1 st lumbrical with
digital nerve and
arteria radialis indici:
2nd lumbrical with digital
artery and nerves
Fig. 42. — Superficial Dissection of the Palm. The central part of the
palmar fascia has been left in position whilst the lateral portions have
been removed to display the short muscles of the thumb and little finger.
and radial margins of the hand the fat becomes softer, and
the amount of fibrous tissue in its midst diminishes. In
connection with the superficial fascia of the palm we have
FOREARM AND HAND 107
to study — (1) the palmaris brevis ; (2) the superficial trans-
verse ligament ; and (3) the palmar cutaneous nerves.
The palmaris brevis is a small cutaneous muscle embedded
in the superficial fascia which covers the upper part of the
hypothenar eminence. If it has not already been exposed
by the reflection of the skin, carry the knife transversely
through the granular fat on the ulnar margin of the palm
immediately below the anterior annular ligament. The fleshy
bundles of the muscle will come into view. When these
have been cleaned, the muscle will be seen to consist of a
series of distinct fasciculi, which in its lower part are
frequently separated from each other by intervals of varying
width. It constitutes a thin fleshy layer, which covers an
inch and a half or more of the hypothenar eminence.
Externally it takes origin from the anterior annular ligament
and inner border of the central part of the palmar fascia,
whilst internally its fasciculi are inserted into the skin over
the ulnar margin of the hand.
The palmar cutaneous nerves are three in number, and
they arise, as already noted, from the ulnar, median, and
radial nerves. They should now be traced to their ultimate
distribution in the palm of the hand.
The transverse superficial ligament is a band of fibres which
extends across the palm at the roots of the fingers. It is
intimately connected with the skin, and is enclosed within the
folds of integument in the clefts between the fingers.
Dissection. — The palmaris brevis should be reflected by detaching its
fasciculi from their origin, and turning them inwards. In raising the
muscle care must be taken of the ulnar artery and nerve, which lie under
cover of it, and a little nerve-filament from the latter should be traced into
its substance. The granular fat should next be removed from the palm,
and the dense palmar fascia cleaned. Towards the roots of the fingers the
digital vessels and nerves, together with the lumbrical muscles, appear in
the intervals between the slips into which the palmar fascia divides. These
should be defined, and it will be seen that they pass downwards under
cover of the superficial transverse ligament. Having noted this point,
remove the ligament. The digital arteries and nerves for the inner side of
the little finger, and the outer side of the index, appear beyond the area of
the central part of the deep fascia, higher up than the others, and are
consequently liable to injury, unless it be remembered that they occupy
this position.
Palmar Fascia. — The deep fascia of the palm is composed
of three portions — a central and two lateral. The lateral
parts are thin and weak, and are spread over the muscles
108 THE UPPER LIMB
which constitute the thenar and hypothenar eminences on
the outer and inner margins of the palm. The central portion
of the palmar fascia, on the other hand, is exceedingly strong
and dense, and is spread out over the middle of the palm.
It counteracts the effect of pressure in this region, and
effectually protects the vessels, nerves, and tendons over
which it is stretched. Its strength differs considerably in
different hands, and it is seen to best advantage in the horny
hand of a labourer, or of a mechanic who has been in the
habit of handling heavy implements. In shape it is triangular.
Above, it is narrow and pointed, and at the wrist it is attached
to the anterior annular ligament, and receives the insertion
of the flattened tendon of the palmaris longus. As it
approaches the heads of the metacarpal bones it expands, and
finally divides into four slips, which separate slightly from
each other, and pass to the roots of the four inner digits. It
gives no slip to the thumb. For the most part it is composed
of longitudinal fibres, but, where it divides, a series of strong
and very evident transverse fibres pass across it in relation
to its deep surface, and bind together its diverging slips.
In the three intervals between the digital slips of the
palmar fascia, the digital arteries and nerves, together with
the corresponding lumbrical muscles, make their appearance.
The connections of the four digital slips of the palmar
fascia must be closely examined. Each lies in front of the
two flexor tendons proceeding to the finger with which it is
connected, and each will be observed to divide into two
portions, so as to form an arch under which these tendons
pass. This arch is connected with the flexor sheaths, which
bind the tendons to the front of the finger, and the two
portions which form it are carried backwards, to obtain
attachment to the transverse metacarpal ligament, which
stretches transversely across the front of the heads of the
metacarpal bones. These relations can only be satisfactorily
made out by dividing the arch, and slitting the slip of fascia
in an upward direction.
Fascial Compartments of the Palm. — Two weak septa
proceed into the palm from the margins of the strong central
portion of the palmar fascia. They join a layer of fascia,
which is spread out over the interosseous muscles and the
deep palmar arch, and they thus subdivide the palm into
three fascial compartments, viz., a central, containing the
FOREARM AND HAND 109
flexor tendons, the lumbrical muscles, the superficial palmar
arch, and the terminal branches of the median nerve ; an
ifiner, enclosing the short muscles of the little finger ; and an
outer, enclosing the short muscles of the thumb.
Dissection. — Raise the central part of the palmar fascia. Divide its
narrow upper part, throw it downwards, and finally remove it completely.
The superficial palmar arch is the most superficial of the structures now
exposed. Trace the ulnar artery into it, and follow the digital branches
which it gives off. The slip of fascia which binds the ulnar artery to the
front of the annular ligament may now be removed. The median and
ulnar nerves must also be dissected. The muscular branches, which the
median gives to the muscles of the thenar eminence, are especially liable to
injury. They come off in a short, stout stem, almost in a line with the
lower margin of the anterior annular ligament, and at once turn outwards
to reach the short muscles of the thumb, to some of which they are
distributed. The nerve twigs to the two outer lumbricals must also be
looked for. They spring from the digital branches of the median, which
go to the radial side of the index and to the cleft between the index and
middle fingers.
In order that the digital vessels and nerves may be traced to their
distribution, the skin must be reflected from the fingers. This can be done
by making an incision along the middle of each digit, and turning the
integument outwards and inwards. As the skin is raised from the lateral
aspects of the different digits the cutaneous ligaments of the phalanges
(Cleland) will come into view. These are fibrous bands, which spring
from the edges of the phalanges behind the digital vessels and nerves.
They are inserted into the skin so as to form a strong fibrous septum on
each side of each finger. They retain the integument in proper position
during the different movements of the digits.
Superficial Palmar Arch (arcus volaris superficialis). — The
ulnar artery, when traced into the palm, is found to form
the superficial palmar arch — an arterial arcade, which lies
immediately subjacent to the deep fascia.
The ulnar artery enters the palm by passing downwards in
front of the annular ligament, close to the outer side of the
pisiform bone. A short distance below this it curves out-
wards, across the palm, and, near the middle of the thenar
eminence, it is joined by the superficialis volae branch of the
radial, or, more frequently, by a twig from the arteria radialis
indicis or arteria princeps pollicis. The convexity of the arch
is directed downwards towards the fingers, and its lowest
point corresponds with a line drawn across the palm from the
lower border of the outstretched thumb.
Throughout its entire extent the superficial palmar arch
lies very near the surface. Its inner part is covered by the
palmaris brevis muscle ; beyond this it is placed immediately
behind the central part of the palmar fascia. As it is followed
I IO
THE UPPER LIMB
from the inner to the outer side of the hand it will be seen to
rest upon — (a) the anterior annular ligament ; (b) the short
muscles of the little finger ; (c) the flexor tendons, and the
digital branches of the median nerve.
Flexor carpi ulnaris
Ulnar artery
Dorsal branch of ulnar nerve
Ulnar nerve
crr~
Deep branch of ulnar nerve— ^SgJLi
Abductor minim
Deep branch of ulnar artery
Superficial part of ulnar
Opponens minimi
Abductor minimi
digiti
Flexor brevi>
minimi digiti
4th lumbrical
3rd lumbrical
Flexor sublimis digitorum
Flexor carpi radialis
Median nerve
Radial artery
Superficialis volae artery
Anterior annular ligament
Extensor ossis metacarpi pollici>
^- — Abductor pollicis
. ^^L_ Opponens pollicis
>sS^ Median nerve
Flexor brevis pollicis
Abductor pollicis
Superficial palmar
arch
Adductor transversus
pollicis
1st lumbrical
2nd lumbrical
Fig. 43. — The parts in the Palm which are displayed by the removal of the
Palmar Fascia. In the specimen from which the drawing was taken the
arteria radialis indicis and the arteria magna pollicis took origin from
the superficial palmar arch.
Branches of the Superficial Palmar Arch. — Small branches
proceed from the superficial palmar arch for the supply of
the integument and adjoining short muscles of the palm. As
the ulnar artery leaves the surface of the anterior annular
FOREARM AND HAND in
ligament it gives off its profunda branch ; whilst from the
convexity of the arch proceed four digital branches.
The profunda artery is a small vessel, which at once
disappears from view by passing backwards in the interval
between the abductor minimi digiti and the flexor brevis
minimi digiti. It will be traced to its termination in the
deep dissection of the palm.
The four digital arteries form the palmar collateral branches
for both sides of each of the three inner fingers and for the
ulnar side of the index finger. The first digital artery runs
downwards upon the short muscles of the little finger, to which
it» gives twigs, and then it is carried along the ulnar side of
the little finger. The second digital artery proceeds towards
the interval between the roots of the little and ring fingers
and divides into two branches {collateral arteries), which run
along the contiguous sides of these digits. The third digital
artery supplies in like manner the adjacent sides of the
ring and middle fingers ; whilst the fourth digital artery deals
similarly with the contiguous margins of the middle and
index fingers.
There are certain points in connection with these digital
arteries, during their course in the palm and along the sides
of the fingers, which must be noted. In the palm the
undivided trunks lie in the intervals between the flexor
tendons and in front of the digital nerves and the lumbrical
muscles. Along the sides of the fingers they show a different
relation to the nerves : the nerves are now in front, and the
arteries behind. Upon the terminal phalanx the two collateral
branches join to form an arch, from which proceed great
numbers of fine twigs, to supply the pulp of the finger, and
the bed upon which the nail rests.
Each digital artery at the point at which it divides is
joined by the corresponding interosseous branch of the
•deep palmar arch. The collateral branches give a liberal
supply of twigs to the integument, sheaths of the tendons,
and joints of the fingers.
Median Nerve. — The median nerve enters the palm by
passing behind the anterior annular ligament with the flexor
tendons. In this part of its course it is enveloped by the
synovial sheath which is wrapped around the tendons.
Further, before it emerges it assumes a flattened form, and
•divides into two portions. Of these, the external division is
ii2 THE UPPER LIMB
slightly the smaller of the two, and gives off — (i) a stout
short branch to some of the intrinsic muscles of the thumb ;
(2) three digital branches which go to the two sides of the
thumb and the radial side of the index finger.
The muscular branch takes origin at the lower border of
the annular ligament, and at once turns outwards to supply
the abductor pollicis, the superficial head of the flexor brevis
pollicis, and the opponens pollicis.
The digital nerves which run along the ulnar side of the
thumb, and the radial side of the index, give several branches
to the fold of integument which stretches between the roots
of these digits ; whilst the long digital branch to the radial
border of the index gives a minute twig to the first or
outermost lumbrical muscle.
The larger internal division of the median nerve divides
into two branches. Of these one runs towards the cleft
between the index and middle fingers, and splits into the
collateral branches for the adjacent sides of these digits.
From this nerve a twig to the second lumbrical muscle is
given off. The second branch of the internal division of
the median proceeds towards the cleft between the middle
and ring fingers, and divides into the collateral branches for
their contiguous margins. In some instances the latter nerve
supplies a twig to the third lumbrical muscle.
In the palm the digital branches of the median proceed
downwards behind the superficial palmar arch, but as they
approach the fingers they come to lie in front of the digital
arteries which, in many cases, may be observed to pass
through, or perforate, the nerves. As the digital nerves lie
upon the sides of the fingers, numerous branches are given
to the integument ; and if the dissector exercises sufficient
patience and care in the dissection, he will notice attached
to the nerve twigs numerous minute, oval, seed-like bodies.
These are the Pacinian bodies. At the extremity of the fingers
the digital nerves divide into two terminal branches. Of these,
one ramifies in the pulp, whilst the other inclines backwards
to reach the bed upon which the nail rests. Several twigs
pass to the back of the fingers, and these are chiefly responsible
for the supply of the integument on the posterior aspect of
the second and third phalanges.
Ulnar Nerve. — The ulnar nerve enters the palm by-
passing in front of the anterior annular ligament. It lies
FOREARM AND HAND 113
secure from the effects of pressure under the shelter of the
pisiform bone, and upon the inner side of the ulnar artery.
At this level it divides into two terminal branches — a super-
ficial and a deep.
.The deep bra?ich of the ulnar is continued downwards upon
the annular ligament, and associates itself with the profunda
branch of the ulnar artery. It leaves the present dissection
by passing backwards between the abductor and the flexor
brevis muscles of the little finger.
The superficial branch of the ulnar nerve runs downwards
under cover of the palmaris brevis, to which it gives a branch
of supply, and then divides into two digital branches. One
of these proceeds obliquely over the short muscles of the little
finger to gain the inner side of that digit ; the other descends
to the cleft between the little and ring fingers, and divides
into the collateral branches for the adjacent sides of these
digits. A branch of communication passes from the second
digital branch of the ulnar nerve to the adjoining digital
branch of the median nerve.
The digital branches of the ulnar nerve are distributed on
the sides of the fingers in precisely the same manner as those
derived from the median.
Anterior Annular Ligament. — This is a thick, dense,
fibrous band, which stretches across the front of the carpal
arch, so as to convert it into an osteo-fibrous tunnel for the
passage of the flexor tendons into the palm. On each side it
is attached to the two piers of the carpal arch, viz., on the
outer side to the tubercle of the scaphoid and the ridge of the
trapezium, and on the inner side to the pisiform bone and the
hook of the unciform. Its upper margin is in a measure con-
tinuous with the deep fascia of the forearm, of which it may
be considered to be a thickened part ; whilst below, it is
connected with the palmar fascia.
Upon the anterior surface of the annular ligament the
expanded tendon of the palmaris longus is prolonged down-
wards to the central part of the palmar fascia, whilst on each
side several of the short muscles of the thumb and little
finger take origin from it. Close to its inner attachment the
ulnar artery and nerve find their way into the palm by pass-
ing in front of the ligament, and a strong slip of fascia which
bridges over these may be looked upon as an accessory
attachment of the ligament, seeing that it springs from the
vol. 1 — 8
ri4
THE UPPER LIMB
pisiform bone and tendon of the flexor carpi ulnaris, and
joins the front of the annular ligament beyond the artery
and nerve.
The tunnel which the anterior annular ligament forms with
the palmar concavity of the carpus is transversely oval in
shape, and below, it opens into the middle compartment
of the palm. Through it pass the tendons of the flexor
sublimis, the flexor profundus digitorum, the tendon of the
Palmaris longus
Median nerve
Flexor longus pollicis
Superficialis vols
Flexor carpi radialis
Short muscles of thumb \
\nterior annular
ligament
Ulnar artery
Palmaris brevis muscle
Ulnar nerve
Short muscles of
little finger
F-Cxtensor ossis meta-
carpi pollicis
Extensor primi inte
nodii pollicis
Radial artery
Extensor secuna
internodii pollici:
Extensor carpi
radialis longior /
Radial nerve
Extensor
\ carpi ulnaris
Extensor minimi
digiti
Dorsal branch of ulnar
nerve
Tendons of extensor com-
munis and extensor indicis
Kxtensor carpi radialis brevior
Fig. 44. — Transverse section through the Wrist at the level of the Second
Row of Carpal Bones to show the Carpal Tunnel. The Tendons of the
Plexor Sublimis, Flexor Profundus Digitorum, and Flexor Longus
Pollicis are seen within the Tunnel.
flexor longus pollicis, and the median nerve. The relation
of the tendon of the flexor carpi radialis to the annular
ligament is peculiar. . It pierces the outer attachment of the
ligament, and proceeds down in the groove of the trapezium
in a special compartment provided with a special synovial
sheath.
Synovial Sheaths of the Flexor Tendons. — As the flexor
tendons and the median nerve pass through the carpal tunnel
they are enveloped in two synovial sheaths, which at the same
time line the walls of the canal, and thus greatly facilitate the
FOREARM AND HAND 115
free play of the tendons behind the anterior annular liga-
ment. As we have stated, these sheaths are two in number.
One is wrapped around the tendon of the flexor longus
pollicis ; the other invests the tendons of the flexor profundus
and flexor sublimis. Both are prolonged upwards into the
forearm for an inch or more, and both are carried downwards
into the palm in the form of diverticula upon the diverging
tendons. The diverticula in relation to the tendons which go
to the index, middle, and ring fingers, end near the middle of
the palm. Those upon the tendons of the thumb and little
finger, however, are prolonged downwards into these digits,
and line the flexor sheaths which confine the tendons upon
the palmar aspects of the phalanges.
It is not likely that these synovial sheaths have been preserved intact
throughout the previous dissection of forearm and palm ; but should they
turn out to be uninjured, a very striking demonstration may be obtained
by inflating them with air by means of the blow -pipe. The apertures
through which the air is introduced should be made at the upper margin of
the annular ligament.
It is said that the synovial sac which invests the tendons
of the flexor sublimis and flexor profundus is divided by a
vertical partition into two compartments, and that the outer of
these communicates, by means of a small aperture near the
upper border of the annular ligament, with the synovial sheath
of the tendon of the flexor longus pollicis.
Flexor Tendons. — Open the carpal tunnel by making a
vertical incision through the anterior annular ligament at its
middle. The arrangement of the flexor tendons can now be
studied, and the synovial sheath dissected from the surface of
each. The tendon of the flexor longus pollicis occupies the
outer part of the canal, and gaining the palm turns outwards
to reach the phalanges of the thumb. The four tendons of
the flexor sublimis are arranged in pairs behind the annular
ligament; those for the little and index fingers lying behind
those for the ring and middle fingers. Of the tendons of the
flexor profundus, only that for the index finger is distinct and
separate ; the other three as a rule remain united until they
emerge from under cover of the annular ligament.
In the central compartment of the palm the flexor tendons
diverge from each other, and two, viz., one from the flexor
sublimis, and one from the flexor profundus, go to each of
the four fingers. From the tendons of the flexor profundus
1— 8 a
n6
THE UPPER LIMB
the lumbrical muscles take origin, and these, with the digital
nerves and arteries, will be seen occupying the intervals be-
tween the tendons as they approach the roots of the fingers.
In the fingers the two flexor tendons run downwards upon
the palmar aspect of the phalanges, and are held in position
by the flexor sheaths. These, therefore, must be studied be-
fore the insertions of the tendons can be examined.
Flexor Sheaths. — The flexor sheaths of the fingers lie
immediately subjacent to the skin and superficial fascia,
and the digital vessels and
nerves run downwards upon
each side of them. Each of
these sheaths, with the phal-
anges of the fingers, forms
an osteo-fibrous canal or tube.
The posterior wall of the
tube is formed by the flat
palmar surfaces of the phal-
anges ; the front wall is com-
posed of the fibrous sheath
which bridges over the ten-
dons, and is attached on each
side to the sharp lateral
margins of the phalanges.
The strength of this sheath
differs very much at different
points. Opposite the centre
of each of the two proximal
phalanges it is composed of
transverse fibres, and it ac-
quires a great thickness and
density, forming a distinct
arch, called the vaginal ligament. Such an arrangement
over the joints, however, would seriously interfere with the
free flexion of the- fingers, and therefore in front of the
articulations between the phalanges the sheath is exceedingly
thin, and is strengthened by oblique interlacing fibres.
The flexor tubes in front of one or more of the fingers
may now be opened. They will be seen to be lined by a
synovial sheath, which is reflected over the enclosed tendons
so as to give each a separate investment. The synovial
sheath of the little finger has been seen to be a direct pro-
Fig. 45. — Diagram to illustrate the ar-
rangement of the Synovial Sheaths
around the Flexor Tendons.
FOREARM AND HAND
i i
iongation from the carpal synovial sheath ; the other three
are distinct from this, and are carried upwards into the palm.
They envelop the tendons of the ring, index, and middle
fingers, as far as a line drawn across the palm immediately
above the heads of the metacarpal bones.
If the flexor tendons be raised from the phalanges certain
synovial folds will be noticed connecting them to the bones.
These are termed the vinculo, accessoria. Of these we dis-
tinguish two kinds, viz., ligamenta brevia and longa. In the
accompanying illustration (Fig. 46) the connections of these
may be seen. The ligamenta brevia are triangular folds,
which connect the tendons near their insertions to the
anterior face of the phalanx. The ligamenta longa are not in-
variably present. They are placed higher up, and are narrow,
weak folds which pass between the tendons and the bones.
Lateral interphalangeal
ligament^ jf^y5
Flexor sheath
Lateral metacarpo-
phalangeal ligament
Ligamenta longa
Fig. 46. — Flexor Tendons of the Finger with Yincula Accessoria.
Insertions of the Flexor Tendons. — The insertions of the
two tendons can now be studied. In front of the first phalanx
the tendon of the flexor sublimis becomes flattened and
folded round the subjacent cylindrical tendon of the flexor
profundus. It then splits into two parts, which pass behind
the tendon of the flexor profundus, and allow the latter to
proceed onwards between them. Behind the deep tendon,
the two portions of the tendon of the flexor sublimis become
united by their margins, and then they diverge, to be
inserted into the borders of the shaft of the second phalanx.1
By this arrangement the flattened tendon of the flexor sub-
limis forms a ring, or short tubular passage, through which
the tendon of the flexor profundus proceeds onwards to the
base of the ungual phalanx, into which it is inserted. In
1 Where the margins of the two slips of the tendon of the flexor sublimis
are united behind the tendon of the flexor profundus, a decussation of fibres
takes place between the two slips.
n8 THE UPPER LIMB
each of the four fingers the same arrangement is found ; the
tendon of the flexor sublimis is inserted by two slips into the
sides of the second phalanx, whilst the tendon of the flexor
profundus is inserted into the anterior aspect of the base of
the terminal phalanx.
Tendon of the Flexor Longus Pollicis. — This tendon pro-
ceeds downwards in the interval between two of the muscles
of the thumb (viz., the superficial head of the flexor brevis
pollicis, and the adductor obliquus pollicis), and also in the
interval between the two sesamoid bones which play upon
the head of the metacarpal bone. Reaching the proximal
phalanx, it enters a fibrous sheath constructed upon a similar
plan to those of the fingers. When this is opened, the
tendon will be observed to be inserted into the front of the
base of the terminal phalanx of the thumb. The synovial
sheath which surrounds the tendon during its passage through
the carpal tunnel is continuous with the sheath which invests
the tendon in front of the phalanges.
Dissection. — Throw forwards the superficial palmar arch. Divide it
on the inside below the origin of the profunda artery, and on the outside
at the point where it is joined by the superficial volar artery. The
median nerve may also be severed and its branches turned aside, but
care should be taken to preserve the two branches which it gives to the
lumbrical muscles, and also the stout branch which enters the muscles
of the thenar eminence. Lastly, cut through the fleshy belly of the
flexor sublimis in the forearm, and, raising its tendons from the carpal
hollow, throw them as far down as possible. The tendons of the flexor
profundus and the attached lumbrical muscles are now fully displayed.
Lumbrical Muscles. — These are four slender fleshy bellies
which arise from the tendons of the flexor profundus
digitorum as they traverse the palm. The first lumbrical
arises from the outer side of the tendon for the index finger ;
the second lumbrical springs from the radial border of the
tendon for the middle finger ; whilst the third and fourth
lumbricals take origin from the adjacent sides of the tendons
between which they lie (viz., the tendons for the medius,
annularis, and minimus). The little muscles pass downwards
and end in delicate tendons on the radial sides of the fingers.
Each is inserted into the outer margin of the dorsal expansion
of the extensor tendon, which lies upon the posterior aspect
of the proximal phalanx.
Dissection. — The flexor profundus may be divided in the forearm and
thrown downwards. Great care must be taken in raising the tendons and
FOREARM AND HAND 119
lumbrical muscles from the palm, because slender twigs from the deep
branch of the ulnar nerve enter the two inner lumbrical muscles on their
deep aspect. These can easily be secured if ordinary caution be observed.
The deep palmar arch and the deep branch of the ulnar nerve are now
exposed, and a favourable opportunity is given for studying the short
muscles of the thumb and little finger.
Short Muscles of the Thumb. — The abductor pollicis forms
the most prominent and external part of the ball of the
thumb. The superficial head of the flexor brevis pollicis lies
immediately to the inner side of the abductor ; and by separ-
ating the one from the other, the opponens pollicis will be
exposed. These three muscles lie to the outer side of the
tendon of the flexor longus pollicis. To the inner side of
this tendon, and placed deeply in the palm, is a fan-shaped
muscular sheet imperfectly separated into an upper and lower
part by the radial artery as it enters the palm. The upper
muscle is the adductor obliquus pollicis^ the lower muscle is the
adductor transversus pollicis.
In dissecting these muscles the muscular branch of the median nerve
must be traced to those which lie upon the outer side of the long flexor
tendon of the thumb, and the deep branch of the ulnar must be followed,
and its branches to the two adductors of the thumb secured.
The abductor pollicis arises from the front of the annular
ligament and the trapezium. It is inserted into the radial
side of the base of the first phalanx of the thumb, and slightly
into the extensor tendon on the dorsum of the first phalanx.
Its nerve of supply comes from the median.
The superficial head of the flexor brevis pollicis1 takes origin
from the annular ligament, and is inserted into the outer side
of the base of the proximal phalanx of the thumb. It is
supplied by the median nerve.
The opponens pollicis springs from the annular ligament
and the ridge on the front of the trapezium. Its fibres
spread out, and are inserted into the entire length of the
radial border of the metacarpal bone of the thumb. Its
nerve of supply is derived from the median.
The adductor obliquus pollicis arises from the bases of the
second and third metacarpal bones, and likewise from the os
magnum, the trapezoid, the trapezium, and the sheath of the
flexor carpi radialis. From this origin the muscle proceeds
1 The term superficial head, applied to this muscle, suggests the presence
of a deep head. Such a head is present. It is the interosseus primus volaris
of Henle (v. p. 139).
I— 8 c
120
THE UPPER LIMB
downwards along the inner side of the tendon of the flexor
longus pollicis, and is inserted into the ulnar side of the base
of the proximal phalanx of the thumb. A strong slip will
generally be seen to deviate outwards from the outer border
of the muscle. This passes under cover of the long flexor
tendon, and joins the superficial head of the flexor brevis
pollicis. The adductor obliquus is supplied by the deep
branch of the ulnar nerve.
The adductor transversus pollicis has a wide origin from the
Os magnum Semilunar
Trapezoid
Scaphoid
Abductor pollicis y
Trapezium .< P
Opponens pollicis / —
Extensor ossis
metacarpi pollicis
Flexor carpi radialis
Adductor obliquus pollici
Adductor transversus pollicis
Unciform
Cuneiform
Flexor carpi ulnaris
Pisiform
Abductor minimi digiti
Flexor brevis
minimi digiti
or carpi ulnaris
Opponens minimi digiti
mar interossei
Fig. 47. — Palmar aspect of Bones of Carpus and Metacarpus with
Muscular Attachments mapped out.
anterior face of the lower two-thirds of the shaft of the
middle metacarpal bone, and from the fascia covering the
interosseous muscles. Its fibres converge as they pass out-
wards, and are inserted along with the adductor obliquus into
the ulnar side of the base of the first phalanx of the thumb.
It is supplied by the deep branch of the ulnar nerve.
Two sesamoid bones are developed in connection with
the tendons of the short muscles of the thumb as they are
inserted on either side of the base of the proximal phalanx.
Short Muscles of the Little Finger. — The abductor ?nini??ii
digiti lies on the inner and superficial aspect of the hypo-
FOREARM AND HAND 121
thenar eminence, and the flexor brevis minimi digiti upon
its outer side. On separating these from each other, the
opponens minimi digiti is seen on a deeper plane, and in the
interval between them.
The abductor minimi digiti (abductor quinti digiti) arises
from the pisiform bone, and is inserted into the ulnar side of
the base of the proximal phalanx of the little finger. It is
supplied by the deep branch of the ulnar nerve.
The flexor brevis minimi digiti (flexor digiti quinti brevis) is
composed of a single fleshy belly which springs from the hook
of the unciform bone and the annular ligament, and is inserted
into the ulnar side of the proximal phalanx of the little
finger, in common with the abductor. This muscle is some-
times much reduced in size, and frequently more or less
completely incorporated with the opponens. Its nerve
supply comes from the deep branch of the ulnar nerve.
The opponens minimi digiti (opponens digiti quinti) arises
from the annular ligament, and the hook of the unciform
bone and its fibres spread cut to obtain insertion into the
entire length of the ulnar margin of the metacarpal bone of
the little finger. The deep bra?ich of the ulnar gives it its
nerve of supply.
Deep Branch of the Ulnar Nerve. — This nerve springs
from the parent trunk on the anterior aspect of the annular
ligament, and gives off a branch which supplies the three
short muscles of the little finger. Accompanied by the deep
branch of the ulnar artery, it then sinks into the interval
between the abductor and flexor brevis minimi digiti, and
turns outwards across the palm under cover of the flexor
tendons. Near the radial border of the palm the deep
branch of the ulnar nerve breaks up into terminal twigs
which supply the adductor transversus pollicis, the adductor
obliquus pollicis, and the first dorsal interosseous muscle.
In its course across the palm it lies along the concavity or
upper border of the deep palmar arch, and sends three fine
branches downwards in front of the three interosseous spaces.
These supply the interosseous muscles in those spaces, while
the two inner also give branches to the deep surfaces of the
two inner lumbrical muscles. The third lumbrical has
frequently a double nerve supply, as it is not uncommon to
find a second twig from the median entering its superficial
aspect.
i22 THE UPPER LIMB
The deep branch of the ulnar may, therefore, be said to
supply all the muscles of the palm which lie to the inner side
of the tendon of the flexor longus pollicis, whilst the median
supplies the three muscles which lie to the outer side of that
tendon. There are two exceptions to this generalisation, viz.,
the two outer lumbrical muscles, which lie upon the inner
side of the tendon, and are yet supplied by the median nerve.
Deep Palmar Arch (arcus volaris profundus). — The artery
which takes the chief part in the formation of this arch is the
radial. This vessel enters the palm, by coming forwards
through the upper part of the first interosseous space between
the two heads of the first dorsal interosseous muscle. In
the present state of the dissection it makes its appearance
between the contiguous margins of the adductor obliquus and
adductor transversus pollicis. It runs inwards upon the inter-
ossei muscles and the metacarpal bones immediately below
their bases. As it approaches the fifth metacarpal bone it is
joined by the deep branch of the ulnar artery, and in this
manner the deep palmar arch is completed.
The deep palmar arch does not show so strong a curve as
the superficial arch, and it is placed at a higher level in the
palm. It is closely accompanied by the deep branch of the
ulnar nerve ; and is separated from the superficial palmar
arch by the group of flexor tendons, the lumbrical muscles,
the branches of the median nerve wThich occupy the middle
compartment of the palm, and also at its inner part by the
flexor brevis minimi digiti, under which the deep branch of
the ulnar artery passes to join the radial.
The brandies which spring from the deep palmar arch are :
(i) the recurrent — a few small twigs which run upwards in
front of the carpus to anastomose with branches of the anterior
carpal arch; (2) superior perforating, which pass backwards
in the upper parts of the interosseous spaces to anastomose
with the dorsal interosseous arteries ; and (3) the palmar
interosseous — three in number — which pass forwards in front
of the interosseous spaces and unite, near the roots of the
fingers, with the corresponding digital arteries from the super-
ficial palmar arch. Sometimes one or more of these branches
enlarge and take the place of the corresponding digital
arteries.
Dissection. — To bring the arteria radialis indicis and the arteria princeps
pollicis into view, the adductor transversus, and the adductor obliquus
FOREARM AND HAND 123
pollicis, must be detached from their origins and turned outwards. The
radial artery is now seen coming forwards between the two heads of the
first dorsal interosseous muscle.
Arteria Radialis Indicis, and Arteria Princeps Pollicis. —
These arteries spring from the radial as it proceeds forwards
between the first and second metacarpal bones.
The arteria radialis iiidicis runs downwards between the
adductor transversus pollicis and the first dorsal interosseous
muscle to the radial border of the index, along which it
proceeds as its outer collateral branch.
The arteria princeps pollicis takes a course downwards and
outwards under cover of the adductor obliquus pollicis, and
gains the front of the metacarpal bone of the thumb. Here
it lies behind the tendon of the flexor longus pollicis, and
divides into the two collateral branches of the thumb. These
branches make their appearance in the interval between the
adductor obliquus and the superficial head of the flexor brevis
pollicis, and are carried forward on either side of the tendon
of the long flexor.
Surgical Anatomy of the Palm and Fingers. — When an abscess forms
in the middle compartment of the palm early surgical interference is
urgently called for. The dense palmar fascia effectually prevents the
passage of the pus forwards, whilst an easy route upwards into the fore-
arm is offered to it by the open carpal tunnel, through which the flexor
tendons enter the palm. It is absolutely necessary, therefore, that before
this can occur the surgeon should make an opening in the palm by means
of which the pus can escape.
In making such an incision it is important to bear in mind the position
of the various vessels which occupy the middle compartment of the palm.
As we have stated, the level to which the superficial palmar arch descends
can be indicated by drawing a line transversely across the palm from the
lower margin of the outstretched thumb. The deep palmar arch lies half
an inch higher. The digital arteries, which spring from the convexity of
the superficial arch, run in a line with the clefts between the fingers. An
incision, therefore, which is made below the superficial arch, and in a
direction corresponding to the central line of one of the fingers, may be
considered free from danger in so far as the vessels are concerned.
The loose synovial sheath which envelops the flexor tendons as they
pass behind the anterior annular ligament has been noticed to extend up-
wards into the lower part of the forearm, and downwards into the palm.
When this is attacked by inflammatory action it is apt to become distended
with fluid (thecal ganglion), and the anatomical arrangement of parts at
once offers an explanation of the appearance which is presented. There is
a bulging in the palm, and a bulging in the lower part of the forearm, but
no swelling at all at the wrist. Here the dense annular ligament resists
the expansion of the synovial sheath, and an hour-glass constriction is
evident at this level.
The fingers are subject to an inflammatory process, termed whitlow,
and, in connection with this, it is essential to remember that the flexor
i24 THE UPPER LIMB
fibrous sheath ends on the base of the distal phalanx in each digit.
When the whitlow occurs below this, in the pulp of the finger, the vitality
of the distal part of the ungual phalanx is endangered, but the flexor
tendons may be regarded as being tolerably safe. When the inflammation
occurs above this, and involves the flexor sheath, as it generally does,
sloughing of the tendons is to be apprehended, unless an immediate
opening is made. And no slight superficial incision will suffice. The
knife must be carried backwards in the centre of the finger, so as to freely
lay open the sheath containing the tendons. Early interference in cases
of whitlow of the thumb and little finger is even more urgently required
than in the case of the other three digits, because, as we have seen, the
digital synovial sheaths of the former are, as a rule, offshoots from the
great carpal bursa, and offer a ready means for the upward extension of
the inflammatory action.
Every amputation of the fingers above the insertion of the tendons of
the flexor profundus involves the opening of the flexor sheaths, and this no
doubt explains the occasional occurrence of palmar trouble after operations
of this kind. The open tubes offer a ready passage, by means of which
septic material may travel upwards into the palm, and, in the case of
the thumb and little finger, into the carpal tunnel and lower part of the
forearm.
Back and Outer Border of the Forearm.
The cutaneous nerves and vessels in this region have
already been studied. The parts which still require to be
examined are : —
i. The deep fascia.
2. The supinator and extensor muscles.
3. The posterior interosseous artery.
4. The perforating or terminal branch of the anterior interosseous
artery.
5. The posterior interosseous nerve.
Deep Fascia. — The deep fascia on the posterior aspect of
the forearm is stronger than that which clothes it in front.
At the elbow it is firmly attached to the condyles of the
humerus and the olecranon process, and it receives a reinforce-
ment of fibres from the tendon of the triceps muscle. Here
also it affords origin to the extensor muscles, and sends strong
septa between them. At the wrist a thickened band — the
posterior annular ligament — is developed in connection with
it. This can readily be distinguished from the thinner
portions of the fascia with which it is continuous above and
below, and it will be observed to stretch obliquely from the
styloid process of the radius inwards and downwards across
the wrist to the inner side of the carpus.
Dissection. — The deep fascia should now be removed, but that portion
of it near the elbow, which gives origin to the subjacent muscles, should be
FOREARM AND HAND 125
left in place. The posterior annular ligament should also be artificially
separated from it, and retained in situ.
Superficial Muscles. — The muscles in this region consist
of a superficial and a deep group. The superficial muscles,
as we proceed from the outer to the inner border of the
forearm, are: — (1) the supinator longus ; (2) the extensor
carpi radialis longior; (3) the extensor carpi radialis brevior; (4)
the extensor communis digitorum; (5) the extensor minimi
digiti ; (6) the extensor carpi ulnaris ; and (7) the anconeus.
This group therefore comprises one supinator, three extensors
of the wrist, two extensors of the fingers, and a feeble ex-
tensor of the forearm at the elbow-joint, viz., the anconeus.
In the lower part of the forearm the extensor communis
digitorum is separated from the extensor carpi radialis brevior
by a narrow interval, and in this appear two muscles belong-
ing to the deep group. These turn round the outer border
of the forearm upon the surface of the radial extensors of the
wrist, and end in tendons which go to the thumb. The upper
muscle is the extensor ossis metacarpi pollicis, and the lower
muscle the extensor primi internodii pollicis. They are placed
in close contact, and so intimately are their tendons connected
that in many cases they appear at first sight to be blended
together by their margins.
Four of the superficial muscles arise by a common origin
from the front ot the external condyle of the humerus,
and at the same time derive fibres from the investing fascia
and the septa it sends in between them. These are the
extensor carpi radialis brevior, the extensor communis
digitorum, the extensor minimi digiti, and the extensor
carpi ulnaris. The superficial muscles should be cleaned,
and isolated as far as possible from each other.
Supinator Longus (brachio-radialis). — This muscle lies
more on the front than on the back of the forearm. It
takes origin in the upper arm from the upper two-thirds of
the external supracondyloid ridge of the humerus and from
the external intermuscular septum. Near the middle of the
forearm a flat tendon emerges from its fleshy belly, and this
proceeds downwards to gain insertion into the outer aspect
of the expanded lower extremity of the radius close to the
base of the styloid process. The nerve of supply to this
muscle comes from the musado-spiral nerve.
Extensor Carpi Radialis Longior. — The Ions; radial ex-
I 26
THE UPPER LIMB
tensor of the carpus is placed behind the supinator longus.
It arises from the lower third of the external supracondyloid
ridge of the humerus, and from the external intermuscular
septum. From the fleshy portion of the muscle a long
tendon proceeds which passes under cover of the posterior
annular ligament, and is inserted into the radial side of the
base of the metacarpal bone of the index finger. This muscle
;is supplied by the musculo-spiral ?ierve.
Extensor Carpi Radialis Brevior. — The extensor carpi
Semilunar
Cuneiform
Pisiform \ y^ "/
Unciform
"Extensor carpi ulnaris
Os magnum
Scaphoid
Extensor carpi radialis brevior
Trapezoid
Trapezium
Extensor carpi radialis longior
C Extensor os-is metacarpi pollicis
Fig. 48. — Dorsal aspect of Bones of Carpus and Metacarpus with
Muscular Attachments mapped out.
radialis brevior is closely associated with the preceding muscle.
It arises by the common extensor tendon from the external
condyle of the humerus ; it also derives fibres from the
external lateral ligament of the elbow-joint, from the investing
deep fascia, and the fibrous septa in connection with it. The
tendon of the muscle accompanies that of the long radial
extensor under cover of the posterior annular ligament, and
is inserted into the radial side of the base of the third meta-
carpal bone immediately beyond the root of its styloid process.
This muscle is supplied by the posterior interosseous nerve.
Extensor Communis Digitorum. — The extensor communis
FOREARM AND HAND
T 2
digitorum takes origin by the common tendon from the
outer condyle of the humerus. The deep fascia and the
intermuscular septa in relation to it also contribute fibres.
Its fleshy belly in the lower part of the forearm sends out
four tendons, which pass under cover of the posterior annular
ligament. On the dorsum of the hand they diverge and
proceed onwards to the four fingers. Their arrangement and
attachments on the dorsum of the hand and fingers will be
afterwards considered. This muscle is supplied by the
posterior interosseous nerve.
Extensor Minimi Digiti. — The extensor minimi digiti is a
slender fleshy belly which at first sight appears a part of the
preceding muscle, but its tendon passes through a special
compartment in the posterior annular ligament. It arises in
common with the extensor communis digitorum. This muscle
is supplied by the posterior interosseous nerve.
Extensor Carpi Ulnaris. — The extensor carpi ulnaris arises,
by means of the common extensor tendon, from the outer
condyle of the humerus, from the fascia of the forearm, and
from the intermuscular septum between it and the extensor
minimi digiti. In the middle third of the forearm it may
also receive some fibres from the strong fascial layer which
binds it to the posterior border of the ulna. The tendon
does not become free from the fleshy fibres until it approaches
close to the wrist. It occupies the groove on the posterior
aspect of the lower end of the ulna, between the head and
styloid process, and passing under cover of the annular
ligament is inserted into the tubercle on the base of the
metacarpal bone of the little finger. This muscle is supplied
by the posterior interosseous nerve.
Anconeus. — The anconeus is a short triangular muscle
placed on the posterior aspect of the elbow-joint. It presents
a narrow origin from the posterior aspect of the external
condyle of the humerus. From this its fibres spread out
the upper fibres passing transversely inwards, whilst the others
proceed inwards and downwards, with an increasing degree
of obliquity towards its lower border. It is inserted into the
outer surface of the olecranon process, and into the upper
third of the posterior surface of the shaft of the ulna.
_ The anconeus is frequently more or less directly continuous with the
triceps, and this, together with the fact that it gets a special branch of
supply from the musculo-spiral nerve, lias led some anatomists to regard it
i28 THE UPPER LIMB
as a piece of the triceps muscle. This is not the case, however ; it belongs
to, and is therefore properly classified with, the group of muscles on the
extensor aspect of the forearm.
The nerve of supply to the anconeus has already been
dissected. It is a long slender branch from the musculo-
spiral, which descends to its destination in the substance of
the internal head of the triceps. In addition to this, the
lower part of the muscle usually receives a twig from the
posterior interosseous nerve.
Dissection. — Reflect the extensor communis digitorum and the extensor
minimi digiti. Divide the fleshy belly of each about its middle, and throw
them upwards and downwards. In doing this care must be taken to
secure and preserve the nerve twigs from the posterior interosseous nerve
which enter these muscles on their deep surface. The posterior interosseous
artery and nerve, together with the deep muscles, are now exposed, and
may be fully dissected. In the lower part of the forearm the terminal part
of the posterior interosseous nerve dips under cover of the extensor secundi
internodii pollicis, to reach the interosseous membrane and the back of the
carpus. In following this part of the nerve, the terminal or perforating
branch of the anterior interosseous artery will be seen appearing on the
back of the forearm, under cover of the extensor secundi internodii pollicis.
Deep Muscles. — These are — (i) The supinator brevis; (2)
the extensor ossis metacarpi pollicis ; (3) the extensor primi
internodii pollicis or extensor brevis pollicis ; (4) the extensor
secundi internodii pollicis or extensor longus pollicis; and (5)
the extensor indicis proprius.
The supinator brevis will be recognised from the close
manner in which it is applied to the upper part of the shaft
of the radius. The other muscles take origin from above down-
wards in the order in which they have been named. The
attachments of the supinator brevis cannot be satisfactorily
studied at present. They will be described at a later stage
of the dissection.
Extensor Ossis Metacarpi Pollicis (abductor longus
pollicis). — This muscle arises from both bones of the fore-
arm, and from the interosseous membrane which stretches
between them. Its origin from the radius corresponds to the
middle third of its posterior surface ; its origin fro?n the ulna
is at a higher level from the outer part of the posterior aspect
of the shaft immediately below the oblique line which marks
the lower limit of the insertion of the anconeus. The muscle
proceeds downwards and outwards, and comes to the surface
in the interval between the extensor communis digitorum and
the extensor carpi radialis brevior. Closely accompanied by
FOREARM AND HAND
i 29
Triceps
Supinator
brevis
Extensor
Radial
„ extensors
Extensor
Extensor ossis meta-
carpi and extensor
brevis pollicis
Extensor communis digitorum
and extensor indicis
Extensor longus
pollicis
Fig. 49. — Posterior aspect of Bones of Forearm with
Attachments of Muscles mapped out.
the extensor primi internodii
pollicis it crosses the two radial
extensors. The tendon which
issues from it at this point is
continued downwards over the
outer side of the expanded
lower end of the radius, and
under cover of the posterior
annular ligament. It is in-
serted into the radial side of
the base of the metacarpal bone
of the thumb. This muscle is
supplied by the posterior inter-
osseous nerve.
Extensor Primi Internodii
Pollicis. — This muscle, fre-
quently called the extensor
brevis pollicis, is placed along
the lower border of the pre-
ceding muscle. It arises from
a small portion of the posterior
aspect of the radius, and also
from the interosseous mem-
brane. Its tendon is closely
applied to that of the ex-
tensor ossis metacarpi pollicis,
and accompanies it under the
posterior annular ligament. It
may be traced on the dorsal as-
pect of the meta-
carpal bone of
the thumb to
the base of the
proximal phal-
anx, into which
it is inserted.
This muscle is
supplied by the
posterior inter -
osseous nerve.
Extensor Se-
cundi Internodii
VOL. I-
i3o THE UPPER LIMB
Pollicis. — The extensor secundi internodii pollicis, or the
extensor longus pollicis, takes origin from the outer part of the
posterior surface of the shaft of the ulna in its middle third,
and also from the interosseous membrane. It, to some extent,
overlaps the preceding muscle, and it ends in a tendon which
passes under cover of the posterior annular ligament. Here
it occupies a deep narrow groove on the back of the lower
end of the radius. On the carpus it takes an oblique
course, and, crossing the tendons of the two radial extensors
and the radial artery, reaches the thumb. It is inserted
into the base of the distal phalanx of that digit. The
extensor longus pollicis is supplied by the posterior inter-
osseous nerve.
When the thumb is powerfully extended in the living person the
tendons of its three extensors become prominent on the outer aspect of the
wrist. The oblique course of the tendon of the extensor secundi internodii
is rendered evident, and a distinct depression between it and the other two
tendons is seen.
Extensor Indicis Proprius. — The extensor indicis arises
below the preceding muscle from a limited area on the
posterior surface of the ulna and from the interosseous mem-
brane. Its tendon accompanies those of the extensor com-
munis under cover of the posterior annular ligament, and
will afterwards be traced to its insertion on the index
finger. This muscle is supplied by the posterior interosseous nerve.
Posterior Interosseous Artery (arteria interossea dorsalis).
— This vessel arises in the front of the forearm, from the
common interosseous branch of the ulnar artery. It at once
proceeds backwards between the two bones of the forearm, in
the interval between the upper border of the interosseous
membrane and the oblique ligament. In the present dis-
section it makes its appearance between the contiguous
borders of the supinator brevis and the extensor ossis
metacarpi pollicis, and then it extends downwards between
the superficial and deep muscles on the back of the forearm.
It gives branches to these, and by the time it has reached the
lower end of the forearm it is greatly reduced in size. In
a well-injected limb it will be seen to end on the back of the
carpus by anastomosing with the anterior interosseous and
the posterior carpal arteries. In addition to the branches
which it supplies to the muscles, it gives off one large branch
called the posterior interosseous recurrent.
FOREARM AND HAXI)
r3*
The posterior i?iterosseous recurrent artery (arteria interossea
-Orbicular ligament of radius
-Posterior interosseous nerve
Posterior inter-^
osseous recurrent
Posterior inter-
osseous artery
Insertion of pronator radii I
Extensor ossis metacarpi
pollicis
Posterior interosseous nerve
Extensor primi internodi
pollicis (extensor brevis)
Extensor indicis
Extensor minimi digit
Extensor communis digitorunr
Posterior radial carpal artery-
Radial artery if
Vic. 50.— Dissection of the Back of the Forearm and Hand.
recurrens) takes origin from the parent trunk as it appears
between the supinator brevis and the extensor ossis meta-
I— 9 a
132
THE UPPER LIMB
carpi pollicis, and turns upwards, under cover of the anconeus
muscle, to reach the posterior aspect of the outer condyle of
the humerus. The anconeus should be detached from its
origin and thrown inwards, in order
that the artery may be traced to its
termination. The interosseous recur-
rent artery will then be seen to end by
anastomosing with the posterior terminal
branch of the superior profunda artery.
Anastomosis around the Elbow-
joint. — The series of inosculations
around the elbow should now be re-
viewed as a whole. A distinct inoscula-
tion will be found to take place upon
both the anterior and posterior aspect
of each condyle of the humerus.
Behind the external condyle the posterior
interosseous recurre?it joins the posterior
branch of the superior profunda : in front
of the same condyle the anterior branch
of the superior profunda communicates
with the radial recurrent. On the inner
side of the joint the anterior and posterior
ulnar recurre?it arteries ascend respectively
in front of and behind the internal con-
dyle, and anastomose, the former with
the anterior branch of the anastomotic,
and the latter with the posterior branch
of the anasto??wtic and the i?iferior pro-
funda.
In this sketch of the anastomosis
around the elbow-joint only the leading
inosculations are mentioned. Rich
interosseous networks of fine vessels are formed
Diagram .of over the olecranon process and the two
i condyles of the humerus. One very
distinct and tolerably constant arch
requires special mention. It is formed by a branch which
crosses the posterior aspect of the humerus immediately above
the olecranon fossa, and connects the posterior branch of the
superior profunda with the posterior branch of the anastomotica.
Posterior Interosseous Nerve (nervus interosseus dorsalis).
Anterior
interosseous
Posterior
Fig. 51.
Anastomosis
the Elbow-joint.
FOREARM AND HAND 133
— This is one of the two terminal branches of the musculo-
spiral, and it reaches the back of the forearm by traversing
the substance of the supinator brevis, and at the same time
winding round the outer aspect of the shaft of the radius.
It emerges from the supinator brevis a short distance above
the artery of the same name, and is carried downwards between
the superficial and deep muscles on the back of the forearm.
Reaching the upper border of the extensor secundi internodii
pollicis, it leaves the posterior interosseous artery, dips under
cover of that muscle, and joins the anterior interosseous artery
on the posterior aspect of the interosseous membrane. It will
afterwards be traced to the back of the carpus, where it ends,
under cover of the tendons of the extensor communis digi-
torum, in a gangliform enlargement.
The branches which spring from the posterior interosseous
nerve in the forearm are given entirely to muscles. Before
it pierces the supinator brevis it gives branches both to it
and to the extensor carpi radialis brevior. After it appears
on the back of the forearm it supplies the extensor com-
munis digitorum, the extensor minimi digiti, the extensor
carpi ulnaris, the three extensors of the thumb, and the
extensor indicis. It therefore supplies all the muscles on
the outer and back aspects of the forearm, with the exception
of the supinator radii longus and the extensor carpi radialis
longior, which derive their nerve -supply directly from the
musculo-spiral. The anconeus also derives its main nerve
of supply from the musculo-spiral, but it also frequently
obtains a second twig from the posterior interosseous nerve.
Terminal Branch of the Anterior Interosseous Artery. —
The terminal or perforating branch of the anterior inter-
osseous artery is a vessel of some size. It appears through
the interosseous membrane, about two inches or so above the
lower end of the forearm. Accompanied by the posterior
interosseous nerve, it runs downwards, under cover of the
extensor secundi internodii pollicis, and ends on the back of
the carpus by anastomosing with the posterior carpal arch
and the posterior interosseous artery.
Dorsal Aspect of the Wrist and Hand.
Upon the dorsal aspect of the wrist and hand we have
still to examine —
1— 9 b
i34 THE UPPER LIMB
1. The radial artery and its branches.
2. The posterior annular ligament.
3. The extensor tendons of the fingers.
Radial Artery. — It is only a small portion of the radial
artery that is seen in this dissection. At the lower end of
the radius the vessel turns backwards below the styloid pro-
cess, and upon the external lateral ligament of the radio-
carpal joint. Having gained the dorsal aspect of the carpus,
it runs downwards upon the scaphoid and trapezium, and
finally disappears from view by turning forwards through the
upper part of the first interosseous space, and between the
heads of origin of the first dorsal interosseous muscle (Fig.
41, p. 104). In the palm it takes the chief share in the
formation of the deep palmar arch.
While the radial artery rests on the external lateral liga-
ment, it is deeply placed, and is crossed by the tendons of the
extensor ossis metacarpi and the extensor primi internodii
pollicis. On the carpus it lies nearer the surface, and is
crossed obliquely by the third extensor tendon of the thumb,
viz., the tendon of the extensor secundi internodii pollicis.
It is accompanied by two venee comiies and some fine filaments
from the musculo-cutaneous nerve which twine around it.
The branches which spring from the radial artery in this
part of its course are of small size. They are —
1. The posterior radial carpal.
2. The first dorsal interosseous.
3. The two arterite dorsales pollicis.
4. The arteria dorsalis indicis.
The posterior radial carpal artery takes origin on the outer
aspect of the wrist, and runs inwards upon the carpus, to join
the corresponding carpal branch of the ulnar artery. The arch
thus formed is placed under cover of the extensor tendons, and
gives off two branches which run downwards in the third and
fourth intermetacarpal intervals. They are termed the second
and third dorsal interosseous arteries.
The first dorsal interosseous artery arises, as a rule, from the
radial trunk, although not infrequently it may be seen to spring
from the posterior carpal arch. It extends downwards in the
second intermetacarpal interval.
The three dorsal interosseous arteries are brought into
connection with the arteries in the palm by communicating
branches. They are joined by the three perforating twigs of
FOREARM AND HAND
*35
the deep palmar arch. These make their appearance on the
dorsum between the heads of the three inner dorsal interos-
seous muscles. Further, at the lower ends of the interosseous
spaces the dorsal interosseous arteries usually send inferior
perforating branches to join the corresponding digital arteries
in the palm.
The two dorsal arteries of the thumb run downwards upon
either side of that digit.
The dorsal artery of the index is distributed on the radial
side of the index.
Posterior Annular Ligament. — This has been seen to be
an aponeurotic band which stretches obliquely across the wrist.
Extensor secundi
internodii pollicis
Extensor carpi
radialis brevier
Extensor carpi
radialis Iongior1
Extensor primi W-
internodii pollicis ]St ji
Extensor ossis f| j|
metacarpi pollicis
Radiai artery
Flexor longus pollicis
Flexor carpi radiali
Median nerve
Palmaris
longus
FlG. 52. — Transverse section through Forear
to show the arrangement of
Extensor communis
digitorum
Extensor indicis
Extensor
minimi digiti
__ Extensor
carpi ulnaris
Flexor
sublimis
Flexor
rotundas
Ulnar artery
and nerve
Flexor carpi ulnaris
m immediately above Wrist-joint
the Tendons.
It is merely a thickened portion of the deep fascia, and its
attachments are so arranged that it does not interfere with the
free movement of the radius and hand during pronation and
supination. On the outer side it is fixed to the outer margin
of the lower end of the radius, whilst on the inner side it
is attached to the cuneiform and pisiform bones, and also to
the palmar fascia. In the case of the anterior annular liga-
ment one large compartment, or tunnel, is formed for the flexor
tendons ; not so in the case of the posterior annular ligament.
Partitions or processes proceed from its deep surface, and
these are attached to the ridges on the dorsal aspect of the
lower end of the radius, so as to form a series of six bridges
or compartments for the tendons. Each of these is lined by
a special synovial sheath, to facilitate the play of the tendons
1— 9 c
136
THE UPPER LIMB
within it. The different compartments may now be succes-
sively opened up so that the arrangement of the tendons with
reference to the posterior annular ligament may be studied.
The first compartment is placed on the outer side of the
base of the styloid process of the radius, and corresponds with
the broad oblique groove which is present in this part of the
bone. It contains two tendons, viz., the tendons of the extensor
ossis metacarpi and the extensor primi internodii pollicis. The
second compartment corresponds with the outermost groove on
the dorsal aspect of the radius. This is broad and shallow,
and it holds the tendons of the extensor carpi radialis longior,
and of the extensor carpi radialis brevior. The third com-
Fig. 53. (From Luschka. )
1. Middle metacarpal bone.
2. Tendon of flexor sublimis.
3. Tendon of flexor profundus.
4. Second lumbrical muscle.
5. Second dorsal interosseous muscle.
6. Extensor tendon.
I., II., and III. The three phalanges.
partment is formed over the narrow deep intermediate groove
on the back of the lower end of the radius, and through it
the tendon of the extensor secundi internodii pollicis passes
obliquely. The fourth conipartment is placed over the wide
shallow groove which marks the inner part of the dorsal aspect
of the lower end of the radius. It is traversed by five tendons,
viz., the four tendons of the common extensor and the tendon
of the extensor indicis. The. fifth compartment is situated over
the interval between' the lower ends of the radius and ulna.
It contains the slender tendon of the extensor minimi digiti.
The sixth and inner??iost compartment, which corresponds with
the groove on the back of the lower end of the ulna, encloses
the tendon of the extensor carpi ulnaris.
Extensor Tendons of the Fingers. — The four tendons of
the extensor communis digitorum, when they emerge from their
FOREARM AND HAND 137
compartment in the posterior annular ligament, diverge on
the dorsum of the hand to reach the four fingers. The tendon
of the ring finger will be seen to be connected by a tendinous
slip with the tendon on either side of it. This explains the
small degree of independent movement in a backward direction
which the ring digit possesses. The arrangement of the
tendons on the fingers is the same in each case. Upon the
dorsal aspect of the first phalanx the tendon expands so as
to cover it completely. Into the margins of this "dorsal
expansion," the delicate tendons of the lumbrical and inter-
osseous muscles are inserted. Near the first interphalangeal
joint the expansion becomes marked off into three portions —
a central and two lateral. The central part, which is the
weakest, is inserted into the dorsal aspect of the base of the
second phalanx. The stronger lateral portions unite into one
piece beyond this, and gain an insertion into the base of
the ungual phalanx.
The tendon of the extensor India's joins the expansion of
the extensor tendon on the dorsal aspect of the first phalanx
of the index finger.
The tendon of the extensor minimi digiti splits into two
parts. Of these the outer joins the tendon of the common
extensor which goes to that digit, whilst the inner ends in the
dorsal expansion.
Posterior Interosseous Nerve. — The terminal filament of
this nerve can now be traced downwards to the dorsal aspect
of the carpus. It passes under cover of the extensor indicis,
the tendons of the extensor communis, and the posterior
annular ligament. On the carpus it ends in a gangliform
swelling, from which fine twigs proceed for the supply of the
numerous joints in the vicinity.
Dissection. — The limb should now be turned round, so that the trans-
verse metacarpal ligament which stretches across the palmar surface of the
heads of the metacarpal bones may be examined previous to the dissection
of the interosseous muscles.
Transverse Metacarpal Ligament. — The transverse meta-
carpal ligament is a strong band composed of transverse fibres,
which is placed upon the palmar aspect of the heads of the
four metacarpal bones of the fingers. Commencing on the
outer side upon the distal extremity of the index metacarpal,
it ends at the inner margin of the hand upon the head of the
metacarpal bone of the little finger. It is not directly attached
133 THE UPPER LIMB
to the bones, but is fixed to the powerful anterior ligaments
of the four inner metacarpophalangeal joints, and it effectually
prevents excessive separation of the metacarpal bones from each
other.
Dissection. — To obtain a satisfactory view of the interosseous muscles
the adductor transversus pollicis, if not previously reflected, should be
detached from its origin, and thrown outwards towards its insertion into
the thumb. The transverse metacarpal ligament must also be divided in
the intervals between the fingers.
Interosseous Muscles. — The interosseous muscles occupy
the intervals between the metacarpal bones. They are seven
in number ; and are arranged in two groups, viz., a dorsal
and a palmar.
The dorsal interossei (musculi interossei dorsales) are four
in number, and are more powerful than the palmar muscles.
They are best seen on the dorsal aspect of the hand, but they
are also visible in the palm. They act as abductors of the
fingers from a line drawn through the middle digit, and their
insertions are arranged in accordance with this action. Each
muscle arises by two heads from the contiguous surfaces of
the two metacarpal bones between which it lies, and the fibres
converge in a pennate manner upon a delicate tendon. In
the case of the first or outermost dorsal interosseous muscle, this
tendon is inserted into the radial side of the base of the first
phalanx, and also into the radial margin of the dorsal expansion
of the extensor tendon of the index. The second and third
dorsal interosseous muscles are inserted in a similar manner upon
either side of the base of the first phalanx of the middle finger ;
whilst the fourth has a corresponding insertion upon the ulnar
aspect of the base of the first phalanx of the ring finger.
The first dorsal interosseous muscle is frequently termed
the abductor indicts, and between its two heads of origin the
radial artery enters the palm. Between the heads of the other
three muscles the small posterior perforating arteries pass.
The three palmar interosseous muscles (musculi interossei
volares) can only be seen on the palmar aspect of the hand.
They act as adductors of the index, ring, and little fingers
towards the middle digit, and each muscle is placed upon the
metacarpal bone of the finger upon which it acts. The first
palmar interosseous muscle therefore arises from the metacarpal
bone of the index finger, and its delicate tendon is inserted
upon the ulnar side of that digit, partly into the base of the
FOREARM AND HAND 139
first phalanx, and partly into the extensor expansion. The
second palmar interosseous muscle springs from the metacarpal
bone of the ring finger, and has a similar insertion into the
radial side of that digit. The third palmar interosseous muscle
takes origin from the metacarpal bone, and presents a corre-
sponding insertion into the radial side of the first phalanx
and extensor expansion of the little finger. The interosseous
muscles are supplied by the deep branch of the ulnar nerve.
Deep Head of the Flexor Brevis Pollicis (interosseous primus volaris of
Henle). — This minute muscle can best be displayed from the dorsal aspect
of the hand by reflecting the radial head of the first dorsal interosseous
muscle. It arises from the base of the metacarpal bone of the thumb, and
is inserted into the ulnar sesamoid bone of that digit. It is deeply placed,
and is entirely covered in front by the adductor obliquus pollicis.
Tendon of the Flexor Carpi Radialis. — The tendon of this
muscle should now be traced through the groove on the front
of the trapezium to its insertion into the base of the metacarpal
bone of the index. It presents also a minor attachment to
the base of the middle metacarpal bone.
Dissection.— All the muscles around the elbow-joint should be removed.
In raising the brachialis anticus and the triceps from the front and back of
the articulation, some care is required to avoid injury to the anterior and
posterior ligaments. It is advisable to remove the supinator brevis last,
because it is only when this muscle is completely isolated that a proper idea
of its attachments and mode of action can be obtained.
Supinator Radii Brevis. — The supinator brevis envelops
the upper part of the shaft and the neck of the radius,
covering it completely, except on its inner side (Figs. 40,
49, pp. 1 01, 129). It arises from the deep depression below
the lesser sigmoid cavity of the ulna, and also from the ex-
ternal lateral ligament of the elbow and the orbicular liga-
ment of the radius. From this origin the fibres sweep round
the posterior, outer, and anterior surfaces of the radius, and
clothe its shaft as far down as the insertion of the pronator
radii teres. The posterior interosseous nerve traverses the
substance of the muscle, and separates it into two layers.
ARTICULATIONS.
Elbow-joint.
At the elbow - joint (articulatio cubiti) the trochlear
surface of the humerus is grasped by the greater sigmoid cavity
of the ulna. The shallow depression on the upper surface
140
THE UPPER LIMB
of the head of the radius rests upon the capitellum of the
humerus, and its slightly raised rim occupies the groove on the
lower end of the humerus between the capitellum and the
trochlea.
The ligaments of the elbow-joint are arranged in the form
of a capsule which surrounds the articulation on all sides.
From the differences which this exhibits in strength and
attachments four portions are recognised. These are —
1. The external lateral ligament.
2. The internal lateral ligament.
3. The anterior ligament.
4. The posterior ligament.
External Lateral Ligament (ligamentum collaterale
radiale). — This is a strong but short ligamentous band which
is attached above to
the lower aspect of the
Hicep:
Krachialis
anticus'
Median
basilic vein
Brachial
artery
Humerus
nceps
Flexor carpi
r| *> ulnaris
Fig. 54. — Vertical section through Humerus
and Ulna at the Elbow-joint.
external condyle of the
humerus. Below, it is
fixed to the orbicular
ligament of the radius,
and also to the outer
side of the olecranon
process of the ulna be-
hind this. The orbic-
ular ligament, as we
shall afterwards see, is
a strong ligamentous
collar which surrounds
the head of the radius, and retains it in the lesser sigmoid
cavity of the ulna.
Internal Lateral Ligament (ligamentum collaterale ulnare).
— The internal lateral ligament, taken as a whole, is fan-
shaped. By its upper pointed part it is attached to the
internal condyle of the humerus. Inferior!)7 it spreads out to
find insertion into the coronoid and olecranon processes of
the ulna. It consists of three very distinct portions, viz., an
anterior, a posterior, and a transverse.
The anterior part springs from the lower and front part of
the humeral condyle, and is attached to the inner margin of the
coronoid process of the ulna. The posterior pa?i is attached
above to the lower and back part of the humeral condyle,
whilst below it is fixed to the inner border of the olecranon
process. The transverse part consists of a band of fibres,
ARTICULATIONS
141
which bridges across the notch between the olecranon and
the coronoid processes, and is attached to both.
Anterior Ligament. — The anterior ligament is broad, and
composed of fibres which take an irregular course over the
anterior aspect of the joint. It is attached to the front of
the humerus above the coronoid fossa, whilst below it is in-
serted into the margin of the coronoid process of the ulna,
and also into the orbicular ligament of the radius.
Posterior Ligament. — This is weaker than the anterior
ligament. It has a loose attachment to the back of the
Ulna
Internal condyle
jj Anterior part of
W_ internal lateral
ligament
Posterior part of
internal lateral
ligament
K7 Olecranon
Transverse part of
internal lateral ligament
Fig. 55. — Inner aspect of Elbow-joint.
humerus, above the olecranon fossa, and inferiorly it is fixed
to the olecranon and the orbicular ligament of the radius.
Synovial Membrane. — The joint should be opened by
making a transverse incision through the anterior ligament.
The synovial membrane will be seen lining the deep surface
of the ligamentous capsule, and to be reflected from this
upon the non-articular parts of the bones which are enclosed
within the ligaments. In front of the humerus it lines the
radial and coronoid fossae, and behind it is prolonged up-
wards in the form of a loose diverticulum into the olecranon
fossa. In these fossae a quantity of soft oily fat is developed
I42
THE UPPER LIMB
between the bone and the synovial membrane. In this way
pliable pads are formed which occupy the recesses when the
bony processes are withdrawn from them.
Inferiorly the synovial membrane of the elbow-joint is
prolonged downwards into the superior radio-ulnar joint, so
that both articulations possess a single continuous synovial
cavity.
Movements at the Elbow-joint. — The movements at the elbow -joint
must not be confounded with those that take place at the superior radio-
Humerus
Anterior
ligament
External lateral _gg
ligament
Orbicular
ligament
Radius
Internal condyle
Internal lateral
ligament
-Tendon of biceps
-Oblique ligament
Ulna
FlG. 56. — Anterior aspect of the Elbow-joint.
ulnar joint. At the elbow-joint two movements, viz., flexion, or forward
movement of the forearm, and extension, or backward movement of the
forearm, are permitted. '
The muscles which are chiefly concerned in flexing the forearm upon the
upper arm at the elbow-joint are the biceps, the brachialis anticus, the
pronator radii teres, and the supinator longus. The muscles which extend
the forearm at this articulation are the triceps and anconeus.
Dissection. — It is advisable to study the radio -carpal, or wrist -joint,
before the articulations between the two bones of the forearm are examined.
The anterior and posterior annular ligaments, together with the extensor
and flexor tendons, should be completely removed from the wrist. No
ARTICULATIONS 143
attempt, however, should be made to detach the extensor tendons from the
back of the fingers and thumb. The short muscles of the thenar and
hypothenar eminences must also be taken away.
Radio-carpal Joint.
In the radio-carpal joint (articulatio radiocarpea), the
under surface of the radius, with a triangular plate of fibro-
cartilage on its inner side, forms a shallow socket for the
scaphoid, semilunar, and cuneiform bones. The ulna does
not take part in this articulation, as the triangular fibro-
cartilage is interposed between its lower end and the carpus.
The ligaments which retain the opposed surfaces in contact
with each other are four in number, viz. —
1. Anterior. 3. Internal.
2. Posterior. 4. External.
Anterior Ligament (ligamentum radiocarpeum volare). —
The anterior ligament is strong and broad, and it is com-
posed of fibres which run in different directions, although those
which pass obliquely downwards and inwards predominate.
Above, it is attached to the lower border of the inferior
expanded extremity of the radius ; and below, it is inserted
into the bones which constitute the first row of the carpus,
with the exception of the pisiform, viz., into the scaphoid,
semilunar, and cuneiform. Some of the fibres may be
traced beyond the first carpal row on to the os magnum.
Posterior Ligament (ligamentum radiocarpeum dorsale).
— This is weak in comparison with the anterior ligament.
The direction of its fibres is for the most part downwards
and inwards. It arises above from the posterior aspect of
the lower end of the radius, and is attached below to the
scaphoid, semilunar, and cuneiform bones.
External Lateral Ligament. — The external ligament
passes from the tip of the styloid process of the radius to
the scaphoid bone.
Internal Lateral Ligament. — The internal ligament is
round and cord-like. It stretches from the styloid process of
the ulna to the cuneiform and pisiform bones.
The four ligaments which we have described in connection
with the radio-carpal joint are directly continuous with each
other, and in consequence they form a capsule around the
articulation.
144
THE UPPER LIMB
Articular Surfaces. — Divide the anterior and lateral
ligaments of the radio-carpal joint by a transverse incision
carried across the front of the articulation. The hand can
now be bent backwards, so as to expose fully the articular
surfaces opposed to each other in this joint.
The carpal surface is composed of the superior articular
facets of the scaphoid and semilunar bones, and a very
small articular facet on the extreme outer part of the upper
surface of the cuneiform bone. Two interosseous ligaments
stretch across the narrow intervals between these bones —
one on either side of the semilunar — and complete the
carpal surface. Formed of these factors, the carpal surface
is convex both from before backwards and from without
Head of ulna
Styloid process
of ulna
Surface for scaphoid
Groove for tendon of ext.
secundi internodii pollicis
Surface for
semilunar
Apex of triangular
fibro-cartilage
Triangular
fibro-cartilage
Fig. 57. — Carpal Articular Surfaces of the Radius and of the Triangular
Fibro-cartilase of the Wrist.
inwards. Further, it should be observed that the articular
surface extends downwards to a greater extent behind than
in front.
The upper surface or socket (Fig. 57) is elongated from side
to side, and concave in both directions, viz., from before back-
wards and from without inwards. The greater part of it is
formed by the lower end of the radius, but to the inner side
of this the triangular fibro-cartilage of the inferior radio-ulnar
joint likewise enters into its construction. The lower surface
of the radius is divided by a low ridge into an outer triangular
and an inner quadrilateral facet. The outer facet, in the
ordinary position of the hand, is in contact with the greater
extent of the superior articular surface of the scaphoid. The
inner facet of the radius, with the triangular fibro-cartilage,
forms a much larger surface, triangular in outline, which is
ARTICULATIONS 145
opposed to the superior articular surface of the semilunar.
When the hand is placed in line with the forearm no part of
the upper articular surface is allotted to the cuneiform : its
small articular facet rests against the inner part of the capsule
of the joint. When the hand is moved inwards (i.e., adducted),
however, the cuneiform bone travels outwards, and its articular
surface comes into contact with the under surface of the
triangular fibro-cartilage. The semilunar bone at the same
time crosses the bounding ridge on the lower surface of the
radius, and encroaches on the territory of the scaphoid, whilst
a considerable part of the scaphoid surface leaves the radius,
and comes into contact with the outer part of the capsule.
Synovial Membrane. — The synovial membrane of the
radio-carpal joint lines the deep surfaces of the ligaments
forming the capsule, and between the carpal bones it covers
the upper surfaces of the two interosseous ligaments which
complete the carpal surface. Sometimes the triangular fibro-
cartilage is imperfect, and in these cases the synovial membrane
of the radio-carpal joint becomes continuous with the synovial
membrane of the inferior radio-ulnar joint.
Movements at the Radio-carpal Joint. — The hand can be moved in
four directions at the radio-carpal joint. Thus we have — {a) forward
movement, or flexion ; (b) backward movement, or extension ; (c) inward
movement, or adduction ; (d) outward movement, or adduction. In
estimating the extent of these movements in the living person the student
is apt to be misled by the increase of range which is contributed by the
carpal joints. Thus, flexion at the radio-carpal joint is in reality more
limited than extension, although by the combined action of both carpal
and radio-carpal joints the hand can be carried much more freely forwards
than backwards. Adduction, or ulnar flexion, can be produced to a
greater extent than abduction, or radial flexion. In both cases the extent
of movement at the radio-carpal joint proper is very slight, but the range
is extended by movements of the carpal bones. The styloid process
of the radius interferes with abduction.
The muscles which are chiefly concerned in producing these different
movements of the hand at this joint are the following: — {a) flexors — the
flexor carpi radialis, the palmaris longus, and the flexor carpi ulnaris ;
(b) extensors — extensor carpi radialis longior, the extensor carpi radialis
brevior, and the extensor carpi ulnaris ; (c) abductors, or radial flexors
— flexor carpi radialis, extensor carpi radialis longior, extensor ossis
metacarpi pollicis, and the extensor primi internodii pollicis ; (d) adductors,
or ulnar flexors — extensor carpi ulnaris and flexor carpi ulnaris.
Radio-ulnar Joints.
At the radio-ulnar joints the movements of pronation
and supination take place. They are two in number, viz.,
vol. 1 — 10
146
THE UPPER LIMB
a superior and an inferior. At the superior radio-ulnar
articulation (articulatio radioulnaris proximalis), the inner
part of the head of the radius fits into the lesser sigmoid
cavity of the ulna ; at the inferior radio-ulnar joi?it the small
rounded extremity of the ulna is received into the sigmoid
cavity on the inner side of the lower end of the radius. In
connection with these joints there are special ligaments which
retain the bones in apposition. These are — (1) for the
superior radio-ulnar joint, the orbicular ligament; and (2) for
the inferior radio-ulnar joint, (a) an anterior and posterior
ligament, and (b) a connecting triangular fibro-cartilage.
Olecranon process
Lesser sigmoid cavity
Transverse portion
of internal lateral
ligament
Greater sigmoid
cavity
Orbicular ligament Coronoid process
Fig. 58. — Orbicular Ligament of the Radius.
In addition there are other ligaments which pass between
the shafts of the two bones of the forearm, and are therefore
common to the two articulations, viz., the oblique ligament
and the interosseous membrane.
To expose these ligaments the muscles on the front and back of the
forearm must be completely removed.
Orbicular Ligament (ligamentum annulare radii). — This is
a strong ligamentous collar which encircles the head of the
radius, and retains it in the lesser sigmoid cavity of the ulna.
It forms four-fifths of a circle, and is attached by its extremities
to the ulna, in front and behind the lesser sigmoid cavity.
It is somewhat narrower below than above, so that under no
circumstances could the head of the radius be withdrawn
ARTICULATIONS 147
from it in a downward direction, and it is braced tightly
upwards towards the elbow, and greatly strengthened by
certain ligaments of the elbow-joint which become incorporated
with it along its upper border. These are, on the outer side,
the external lateral ligament of the elbow ; in front, a portion
of the anterior ligament ; and behind, a portion of the posterior
ligament of the elbow-joint. Its lower border is free, and
protruding downwards below this will be seen a reflection
of the synovial membrane.
Anterior and Posterior Inferior Radio-ulnar Ligaments. —
These are weak, imperfect bands which can have little influ-
ence in retaining the bones in apposition at the inferior
radio-ulnar joint. They pass between the radius and ulna
in front and behind the articulation, and close in the synovial
membrane upon these aspects of the joint.
Triangular Fibro-cartilage. — The triangular fibro-cartilage
is the true bond of union at the inferior radio-ulnar joint.
It has already been noticed in connection with the radio-
carpal joint, where it extends the radial articular surface
in an inward direction, and is interposed between the lower
end of the ulna and the semilunar bone. It is a thick, firm
plate, attached by its base to the margin on the inner and
lower end of the radius which separates the sigmoid cavity
for the ulna from the facet on the lower surface for the semi-
lunar bone. The apex of the cartilage is directed inwards,
and is fixed to the depression on the lower end of the ulna
at the root of the styloid process. It intervenes between
the inferior radio-ulnar joint and the radio-carpal joint.
Synovial Membranes. — The synovial membrane of the
superior radio-ulnar joint is continuous with that of the
elbow-joint. It is prolonged downwards so as to line the
orbicular ligament, and it protrudes beyond this for a short
distance upon the neck of the radius.
In the inferior radio-ulnar joint the synovial membrane is
remarkable for its laxity. It is called the membrana sacci-
for/w's, and extends upwards in the form of a loose sac for some
distance between the radius and ulna. The synovial cavity
is also prolonged inwards in a horizontal direction between
the lower end of the ulna and the triangular fibro-cartilage.
Sometimes the triangular fibro-cartilage is perforated ; and when this
is the case, the inferior radio-ulnar joint-cavity communicates with the
cavity of the radio-carpal joint.
i48 THE UPPER LIMB
Interosseous Membrane (membrana interossea antibrachii).
— This is a fibrous membrane which stretches across the
interval between the two bones of the forearm, and is
attached to the interosseous border of each. Superiorly it is
deficient. Its upper border does not reach higher than a
point about an inch belowr the tubercle of the radius. The
fibres which compose it run for the most part obliquely
downwrards and inwards from the radius to the ulna, although
several slips may be noticed taking an opposite direction.
The posterior interosseous vessels pass backwards between
the two bones of the forearm immediately above its upper
margin, whilst the terminal branch of the anterior interosseous
artery pierces it about one and a half inches above its lower
end. This ligament, in addition to bracing the two bones
together in such a manner that to some extent forces may
be transmitted from the radius to the ulna, extends the
surface of origin for the muscles of the forearm. By its
anterior surface it gives origin to the flexor profundus and
the flexor longus pollicis muscles, wrhilst by its posterior
surface it contributes fibres to the three extensor muscles of
the thumb and to the extensor indicis.
Oblique Ligament (chorda obliqua). — This is a weak slip
which springs from the outer part of the coronoid process
of the ulna, and extends obliquely downwards and outwards
to find an attachment to the radius immediately below its
bicipital tubercle. It crosses the open space between the
bones of the forearm above the upper border of the inter-
osseous membrane. The oblique ligament is often absent,
and unless the utmost care be taken in removing the muscles
in the preparation of the ligaments it is apt to be injured.
Movements at the Radio-ulnar Joints.— At the radioulnar joints the
movements of pronation and supination take place. When the limb is in
a condition of complete supination the palm of the hand is directed forwards,
the thumb outwards, and the two bones of the forearm are parallel, the
radius lying along the outer side of the ulna. In the movement of pronation
the radius is thrown across the ulna, so that its lower end comes to lie on
the inner side and in front of it. Further, the hand follows the radius in
this movement, and the dorsal aspect of both is directed to the front, and
the thumb is turned inwards.
The dissector should analyse, as far as possible, in the part upon which
he is engaged, the movements at the two radio-ulnar joints which produce
these effects. At the same time it should be remembered that results
obtained from a limb, in which the dissection has proceeded so far, are apt
to be deceptive.
In the case of the superior radio-ulnar joint the movement is simple
ARTICULATIONS 149
enough. The head of the radius merely rotates within the orbicular
ligament, and accuracy of motion is obtained by the cup-like depression on
the upper end of the radius, resting and moving upon the rounded capitellum
of the humerus. But it should be noticed that the head of the radius does
not fit accurately upon the capitellum in all positions of the elbow- joint.
In extreme extension and extreme flexion of the elbow it is only partially
in contact with it. Therefore the semi-flexed condition of the elbow-joint
places the radius in the most favourable position for free and precise
movement at the superior radioulnar joint.
At the inferior radio-tdnar joint the lower end of the radius revolves
around the lower end of the ulna. It carries the hand with it, and describes
the arc of a circle, the centre of which corresponds to the attachment of the
triangular fibro-cartilage to the lower end of the ulna. In this movement
the triangular fibro-cartilage moves with the radius, and travels backwards
on the lower end of the ulna in supination, and forwards in pronation.
But the question may be asked, Does the ulna move during pronation
and supination ? When the elbow-joint is extended to its fullest extent the
ulna remains almost immovable. 'When, however, pronation and supination
are conducted in the semi-flexed limb, the ulna does move. A small
degree of lateral movement at the elbow-joint is allowed, and the lower
end of the ulna during pronation is carried slightly backwards and outwards,
and in the reverse direction during supination.
The muscles which are chiefly concerned in producing supination of the
forearm are — the biceps, the supinator longus, and the supinator brevis.
The biceps, from its insertion into the back part of the radial tubercle, is
placed in a very favourable position, in so far as its supinating action is
concerned. The muscles which act as pronators of the limb are — the
pronator radii teres, the pronator quadratus, and, to a certain extent, the
flexor carpi radialis. The pronator radii teres, from its insertion into the
point of maximum outward curvature of radius, can exercise its pronating
action to great advantage. The balance of power is in favour of the
supinators, and this is due to the preponderating influence of the biceps.
Dissection. — The ulna should be sawn through at the junction of its
middle and lower thirds, and the interosseous membrane where it binds
the lower portion of the bone to the radius divided in a downward direction.
By drawing the lower fragment of the ulna inwards and opening the
membrana sacciformis, the upper surface of the triangular fibro-cartilage
of the wrist will be displayed and its attachments more fully appreciated.
Carpal Joints.
In studying the articulations of the carpal bones we
recognise —
1. A joint between the pisiform and cuneiform bones.
2. Two joints between the remaining bones of the first row. viz..
the scaphoid, semilunar, and cuneiform.
3. Three joints between the bones of the second row, viz. . the
trapezium, trapezoid, os magnum, and unciform.
4. A transverse carpal joint between the two rows of carpal bones.
The pisiform joint is distinct and separate. All the other
i5o
THE UPPER LIMB
joints possess a single joint-cavity. Further, this common
cavity is continued into the articulations between the meta-
carpal bones of the four fingers and the carpus, and also into
the intermetacarpal articulations.
Pisiform Joint. — The pisiform bone is fixed to the cunei-
form by a capsular ligament which surrounds the joint. There
is a separate synovial membrane for this articulation.
The dissector has previously noted that the tendon of the
flexor carpi ulnaris is inserted into the upper aspect of the
pisiform bone. The capsular ligament by itself would be
mMfflM
JH.
Scaphoid
Trapezoid
Trape
Recessus
sacciformis
-Triangular
fibro-cartilage
Semilunar
Cuneiform
nciform
Fig. 59. — Coronal section through Radio-carpal, Carpal, and Carpo-
metacarpal and Inter-metacarpal Joints to show Joint Cavities and
Interosseous Ligaments (diagrammatic).
insufficient to withstand the strain to which this muscle
subjects the articulation. Certain accessory ligaments are
therefore provided, which anchor the pisiform firmly in its
place. These consist of two strong ligamentous bands
which pass from its. lower surface to the hook of the unciform
bone, and to the base of the fifth metacarpal bone. Addi-
tional security is frequently given by bands which connect it
with the bases of the fourth and third metacarpal bones.
First Row of Carpal Bones. — Two dorsal, two palmar, and
two interosseous ligaments pass transversely from the semilunar
to the scaphoid and cuneiform bones which lie on either side
of it.
ARTICULATIONS
i s i
The hvo interosseous ligaments are composed of short
stout fibres which pass between the non-articular portions of
the opposed surfaces of the three bones. They are readily
seen from above, where they complete the carpal surface of
the radio-carpal joint.
Second Row of Carpal Bones. — Three palmar, three dorsal,
and three interosseous ligaments pass transversely between the
adjacent bones.
The interosseous ligament between the os magnum and
unciform is very powerful and strong ; that between the os
magnum and trapezoid is weak, and sometimes absent.
At the present moment the interosseous ligaments are hidden from view,
but they can be studied when the transverse carpal joint between the two
rows of bones is opened.
Transverse Carpal Joint (between the two rows of carpal
bones). — Two lateral ligaments, which pass between the
scaphoid and trapezium on the outer side, and the cuneiform
and unciform bones on the inner side, together with a series
of palmar and dorsal bands, and one interosseous ligament, con-
nect the two rows of carpal bones together.
The palmar ligaments show a tendency to converge upon
the os magnum, whilst the dorsal ligaments are very irregular.
The interosseous ligament is placed between the os magnum
and scaphoid bones, but is not always present.
Dissection. — To display the articular surfaces and interosseous ligaments
of the second row it is necessary to open the transverse carpal joint. This
can be done by dividing the two lateral and the dorsal ligaments. The
interosseous ligament between the scaphoid and os magnum, if present,
will now come into view, and it must be cut, to allow the thorough
separation of the two rows of carpal bones.
Articular Surfaces. — The os magnum and unciform form a
high convexity, which fits into the concavity of the upper row,
whilst the convex lower surface of the scaphoid is received
into a concavity formed by the trapezium and trapezoid.
The two opposing surfaces, therefore, are concavo-convex
from side to side, and adapted the one to the other.
Movements at the Carpal Joints. — The movements at the carpal joints
supplement those at the radio-carpal joint, and tend greatly to increase the
range of movement at the wrist. Between the individual bones of each row
the movement is of a gliding character, and very limited. At the trans-
verse carpal joint forward and backward movement (flexion and extension)
is alone allowed.
i52 THE UPPER LIMB
By the multiplicity of joints in this part of the limb, strength and
elasticity is contributed to the wrist.
Dissection. — The interosseous muscles should now be removed from the
metacarpal bones. At the same time the flexor tendons and lumbrical
muscles may be detached from the fingers. The extensor tendons, how-
ever, should be left in position on the dorsal surface of the metacarpo-
phalangeal and interphalangeal joints. The ligaments which connect the
carpus and metacarpus, and those which pass between the bases of the
four inner metacarpal bones, should be cleaned and defined.
Intermetacarpal Joints.
The four metacarpal bones of the fingers articulate with
each other by their basal or proximal extremities, and are
united together by strong ligaments. The metacarpal bone
of the thumb stands aloof from its neighbours, and enjoys
a much greater freedom of movement.
The ligaments which bind the four inner metacarpal bones
to each other are —
i. A series of palmar and dorsal bands which pass trans-
versely, and connect their basal extremities.
2. Three stout i?iterosseous ligaments, which occupy the
intervals between the basal ends of the bones.
3. The tra?isverse metacarpal ligament, which connects the
heads or distal extremities of the bones (p. 137). This liga-
ment has been removed in the dissection of the interosseous
muscles.
The interosseous ligaments cannot be seen at present, but can be studied
later on by separating the bases of the metacarpal bones from each other.
Carpometacarpal Joints.
The metacarpal bone of the thumb articulates with the
trapezium by a joint which is quite distinct from the other
carpo-metacarpal articulations. A capsular ligament surrounds
the joint, and is sufficiently lax to allow a very considerable
range of movement. On the dorsal and outer aspects of the
articulation it is specially thickened. It encloses a separate
synovial membrane.
The four imier metacarpal bones are connected to the
carpus by palmar and dorsal ligaments, and by one interosseous
ligament.
Each of these metacarpal bones, with the exception of the
ARTICULATIONS 153
fifth, possesses, as a rule, two dorsal ligaments and one
palmar ligament. The articulation of the fifth metacarpal
bone is also closed on the inner side by ligamentous fibres.
The interosseous ligament springs from the contiguous
lower margins of the os magnum and unciform, and passes to
the inner side of the base of the third metacarpal bone.
Dissection. — To display this ligament, divide the bands which connect
the bases of the third and fourth metacarpal bones, and sever the dorsal
ligaments which bind the two inner metacarpal bones to the carpus. The
metacarpal bones thus set free can then be forcibly bent forward, when the
ligament in question will come into view.
Synovial Membranes of the Carpal, Carpo-metacarpal, and
Intermetacarpal Joints. — The pisiform joint, and the carpo-
metacarpal joint of the thumb, possess each a separate
synovial membrane. The other carpal, and carpo-metacarpal,
and also the intermetacarpal articulations present one con-
tinuous joint -cavity, and possess a single synovial membrane.
This complicated and extensive synovial membrane may be
seen to pass upwards in the intervals between the three
bones of the first row (scaphoid, semilunar, and cuneiform) as
far as the interosseous ligaments. It lines the under surfaces
of these, and is excluded by them from the radio -carpal
joint. In a downward direction it may be traced between
the four bones of the second row to the carpo-metacarpal
joints of the four fingers, and from these it finds its way into
the three intermetacarpal articulations.
In some cases the interosseous ligament which connects
the base of the third metacarpal to the os magnum and
unciform shuts off the articulation of the unciform with the
two inner metacarpal bones, and also the innermost inter-
metacarpal articulation from the general joint-cavity. In
such cases a separate synovial membrane is provided for these
articulations.
Dissection. — To display the articular surfaces of the carpo-metacarpal
articulations, the metacarpus should be "detached from the carpus. The
interosseous ligaments between the carpal bones of the second row, and
also between the bases of the four inner metacarpal bones, can likewise be
demonstrated by carrying the knife between the bones, and dividing the
ligaments.
Articular Surfaces. — The base of the metacarpal bone of
the index will be seen to be hollowed out for the reception
of the trapezoid. On the outer side it likewise articulates
154 THE UPPER LIMB
with the trapezium, and on the inner side with the os magnum.
The base of the third metacarpal rests on the os magnum
alone. The base of the metacarpal bone of the ring finger
rests upon the unciform, but also articulates slightly with the
os magnum. The fifth metacarpal bone articulates with the
unciform.
Movements of the Metacarpal Bones. — The opposed saddle -shaped
surfaces of the trapezium and thumb-metacarpal allow very free movement
at this joint. Thus the metacarpal bone of the thumb can be moved — (i)
backwards and outwards (extension) ; (2) forwards and inwards (flexion) :
inwards towards the index finger (adduction) ; (4) outwards (abduction) :
(5) inwards across the palm towards the little finger (opposition). The
muscles which operate upon the thumb are — (1) the three extensors
(extensor ossis metacarpi, extensor primi internodii, and the extensor
secundi internodii), producing extension ; (2) the flexor brevis pollicis and
the opponens pollicis, producing flexion and opposition, two movements
which are similar in character ; (3) the abductor pollicis, which produces
abduction ; (4) and the two adductors (adductor obliquus and the adductor
transversus), which give rise to adduction.
The metacaipal bones of the ??iiddle and index fingers possess very
little power of independent movement. The metacarpal bone of the ring
finger, and more especially the metacarpal bone of the little finger, are
not so tightly bound to the carpus. In clenching the fist they both move
forwards. The metacarpal bone of the little finger is provided with an
opponens muscle, and has a feeble power of advancing forwards and out-
wards to meet the thumb.
Metacarpophalangeal Articulations.
The slightly cupped base of the first phalanx of each
digit articulates with the rounded head of the corresponding
metacarpal bone, and is held in position by three ligaments,
viz., a palmar and two lateral.
The palmar ligament is a dense fibrous plate placed on
the fore aspect of the joint. It is firmly attached to the base
of the phalanx, but only slightly connected with the meta-
carpal bone. Occupying the interval between the two lateral
ligaments, it is united to both by its margins, so that the
three ligaments are more or less directly continuous.
The palmar ligament also exhibits a close connection with
the transverse metacarpal ligament which stretches transversely
across the heads of the metacarpal bones, and its palmar
surface is grooved for the flexor tendons as they proceed
downwards over the joint. Further, the flexor sheath which
bridges over the tendons is fixed to its borders.
The lateral ligame?its are placed one on either side of
ARTICULATIONS 155
the joint. They are strong, thick, and short bands, which
are attached on the one hand to the tubercle and depression
on the lateral aspect of the head of the metacarpal bone, and
on the other to the base of the phalanx.
Dissection. — The extensor tendon should now be raised from the dorsal
aspect of the joint. By this proceeding the joint is opened, and a
demonstration is afforded of the fact that the metacarpophalangeal joints
are destitute of dorsal ligaments.
A synovial membrane lines the deep surfaces of the liga-
ments in each joint, and also the deep surface of the extensor
tendon, as it passes over the articulation and takes the place
of a dorsal ligament.
Movements at the Metacarpophalangeal Joints. — The movements of
the first phalanx at these joints are— (a) flexion, or forward movement ;
(5) extension, or backward movement ; (c) adduction ; and (d) adduction.
During flexion of the fingers, the first phalanx travels forwards with the
thick palmar ligament upon the head of the metacarpal bone. The
interosseous and lumbrical muscles are chiefly instrumental in producing
this movement.
The first phalanges of the fingers in the movement of extension can
only be carried backwards to a very slight degree beyond the line of the
metacarpal bones. The extensor communis and the special extensors of the
index and little finger are the muscles which operate in this case.
Abduction and adduction are movements of the first phalanx away from
and towards a line prolonged downwards through the middle finger, and
are seen when the fingers are spread out and again drawn together. The
abductor minimi digit i and the dorsal interosseous muscles act as abductors
of the fingers at these joints, whilst the palmar interosseous muscles operate
as adductors of the little, ring, and index fingers. In the case of
the middle digit, the second and third dorsal interosseous muscles act
alternately as abductors and as adductors. In connection with the
movements of abduction and adduction, it should be noticed that in the
extended position of the fingers they are very free ; but if flexion be
induced, the power of separating the fingers becomes more and more
restricted, until it becomes absolutely lost when the hand is closed. An
examination of the lateral ligaments will afford the explanation of this.
These " are attached far back on the metacarpal bones, so as to be much
nearer to their inferior ends than to their palmar aspects" (Cleland).
Consequently, while they are comparatively lax in the extended position of
the fingers, the further flexion advances the tighter they become, and in
this way they interfere with the lateral movements of the first phalanges.
The first phalanx of the thumb has only a limited range of movement
at the metacarpo-phalangeal joint.
Interphalangeal Joints.
The ligaments connecting the phalanges are arranged upon
a plan identical with that already described in connection
156 THE UPPER LIMB
with the metacarpophalangeal joints. This should not be
made an excuse, however, to slur them over.
Movements. — From the manner in which the articular surfaces are
adapted to each other, flexion and extension are the only movements which
can take place at the interphalangeal joints. Flexion of the second
phalanges of the fingers is brought about by the flexor sublimis, and of
the ungual phalanges by the flexor profundus. Extension of the phalanges
at the interphalangeal joints is largely produced by the interosseous and
lumbrical muscles acting through the extensor tendons, into which they are
inserted. These muscles, therefore, whilst they flex the first phalanx at
the metacarpophalangeal joints, extend the second and ungual phalanges
at the interphalangeal joints.
In the case of the thumb, the long flexor and the extensor secundi
internodii pollicis operate at the interphalangeal joint.
GLUTEAL REGION 157
THE LOWER LIMB.
On the morning of the third day after the subject has
been brought into the dissecting-room, it is placed upon
the table with its face downwards and its chest and pelvis
supported by blocks (Fig. 1, p. 3). In this position it is
allowed to remain for four days, and during this time the
dissector of the lower limb has a very extensive dissection to
perform. He has to dissect — (1) the gluteal region; (2) the
popliteal space ; and (3) the back of the thigh. With so
much work before him, and being limited as to the time
in which it must be done, it is necessary that he should
apportion the four days at his disposal so as to complete the
dissection before the body is turned. The first two days he
should devote to the study of the gluteal region ; the third
day may be given to the popliteal space ; and on the fourth
day he should undertake the dissection of the back of the
thigh, and revise the work of the three preceding days.
GLUTEAL REGION.
In this region the following are the parts which will be
displayed in the course of the dissection : —
1. Superficial fascia.
2. Cutaneous nerves and blood-vessels.
3. Deep fascia.
/"The gluteus maximus ; (and after this has been
reflected).
Three synovial bursce.
Gluteus medius and minimus.
Pyriformis.
The two gemelli and the tendon of the obturator
4. Muscles, . . \ internus.
The tendon of the obturator externus.
The quadratus femoris.
Upper border of the adductor magnus.
The origin of the hamstrings from the tuberosity
of the ischium.
vThe upper part of the vastus externus.
5. The great sacro-sciatic ligament.
f Gluteal.
6. Blood-vessels, j r^eraal pudic.
I Internal circumflex.
158 THE LOWER LIMB
7. Nerves, . . \
Superior gluteal.
Great sciatic.
Small sciatic.
Internal pudic.
Nerve to obturator internus.
Nerve to quadratus femoris.
Special branches to gluteus maximus (inferior
gluteal nerve).
Supposing that two days are allowed for the above dissection, the first
day's work should consist — (1) in the dissection of the parts superficial to
the gluteus maximus ; (2) in the cleaning and reflecting of this muscle ; (3)
in tracing and defining the various nerves and blood-vessels which enter its
deep surface. On the second day the parts which are exposed by the
reflection of the gluteus maximus should be dissected.
Surface Anatomy. — Before the skin is reflected, the surface
markings of the gluteal region require examination. On each
side, the prominence of the nates is seen to form a round,
smooth elevation. Below, the nates are separated, in the
middle line, by a deep fissure — the natal cleft. This cleft, if
traced upwards, almost disappears over the prominence
formed by the coccyx and lower part of the sacrum. The crest
of the ilium can be felt along its whole length, and in the well-
formed male it appears as a groove — the iliac furrow . Traced
forwards, the crest terminates in the anterior superior spine of
the ilium ; traced backwards, it ends in the posterior superior
spine of the ilium. The position of the latter is indicated
by a faint depression or dimple which lies on a level with the
second spine of the sacrum, and it corresponds with the
middle of the sacro-iliac articulation. The prominence of the
nates is chiefly formed by the gluteus maximus muscle, covered
by a thick layer of fat. A deep transverse groove, produced
by a fold of skin and fascia, limits the gluteal elevation below.
This is called " the fold of the nates " (gluteal sulcus), and is
sometimes said to correspond with the lower border of the
gluteus maximus muscle. It can easily be shown that this is
not the case. Its inner end lies below the lower margin of the
muscle, but as it proceeds transversely outwards it crosses the
muscle-border, and finally comes to lie on the surface of the
muscle. In disease of the hip-joint, the buttock loses its
prominence, whilst the fold of the nates becomes faint. The
tuberosity of the ischium may be felt below the lowrer border
of the gluteus maximus by placing the fingers in the inner part
of the fold of the nates and pressing upwards. A line drawn
from the most prominent part of this tuberosity to the
GLUTEAL REGION 159
anterior superior spine of the ilium is called Nelaton's line.
This line passes over the top of the great trochanter and
crosses the centre of the acetabulum. It is used by the
surgeon in the diagnosis of dislocations and other injuries
of the hip-joint. The great trochanter of the femur may be
felt at a point about six inches below the highest part of the
crest of the ilium. It can be seen in thin subjects, but it does
not form so projecting a feature of this region as might be
expected from an inspection of the skeleton, because the
thick tendon of the gluteus medius is inserted into its outer
surface, and it is moreover covered by the aponeurotic in-
sertion of the gluteus maximus.
Reflection of Skin. — Incisions. — (1) From the posterior superior spine
of the ilium in a curved direction along the crest of the ilium, as far
forwards as the position of the body will permit ; (2) from the posterior
extremity of this curved incision obliquely downwards and inwards to the
middle line of the sacral region, and then perpendicularly downwards to
the tip of the coccyx ; (3) from the tip of the coccyx obliquely downwards
and outwards over the back of the thigh. When properly carried out, this
incision intersects the fold of the nates at about its middle point, and
terminates a little below the upper third of the thigh (Fig. 1, p. 3).
A large flap of skin is thus marked out, and this must be raised from
the subjacent superficial fascia and thrown outwards. On the right side of
the body, the dissector begins at the crest of the ilium and works downwards
and forwards ; whilst on the left side he commences over the coccyx and
works upwards and forwards.
Superficial Fascia. — The superficial fascia is now exposed,
and it is seen to partake of the same characters as the cor-
responding layer of fascia in other parts of the body. It
presents, however, certain special peculiarities. It is much
more heavily laden with fat — more particularly so in the
female ; it thickens over the lower and upper margins of the
gluteus maximus, and it becomes tough, elastic, and stringy
over the ischial tuberosity, so as to form a most efficient
cushion upon which this bony prominence rests while the
body is in the sitting posture.
Cutaneous Nerves (Fig. 60). — The superficial fascia forms
a bed in which the cutaneous nerves ramify before they enter
the skin. In this region the cutaneous nerves are very
numerous, and they are derived from a great variety of
sources. Some proceed from the posterior primary divisions
of the spinal nerves, whilst others are branches of the anterior
p?'imary divisions of the spinal nerves.
From the posterior primary divisions there are usually
i6o
THE LOWER LIMB
six — three from the sacral
Lumbar nerves
Iliac branches of last
dorsal and ilio-hypo- ■
gastric
Sacral nerves -
Perforating
cutaneous
Branches from
small sciatic
y !i\\
t
X
External cutaneous K
I
Long pudendal — *"■
Small sciatic — B
w.
Internal cutaneous-
External cutaneous
tV
Internal cutaneous
\<c
m-M
nerves, and three from the
lumbar nerves. The three
sacral nerves reach the sur-
face by piercing the gluteus
maximus muscle close to
its origin from the sacrum
and coccyx. They are
usually of small size and
pierce the muscle in a line
drawn from the posterior
superior iliac spine to the
tip of the coccyx. The
largest is found opposite
the lowest piece of the
sacrum, the highest about
an inch above this, and the
lowest about the same dis-
tance below it.
Owing to the coarseness of the
muscular fasciculi of the gluteus
maximus between which they
appear, they are somewhat diffi-
cult to find. In looking for them,
it is best to cut right down through
both superficial and deep fasciae,
so as to secure them as they
emerge from the muscle.
The three lumbar nerves
are easily found. They
cross the crest of the ilium
at a point corresponding
to the outer limit of the
attachment of the erector
spinas to the innominate
bone. They pass down-
wards and slightly forwards
in the superficial fascia,
and run in different planes,
the larger trunks being
placed deeper than the
smaller branches. They
communicate with one another and with the sacral nerves. A
few twigs may be followed as far as the great trochanter.
Nervus communicans_
fibularis
Small sciatic -
Nervus communicans_
tibialis"
External saphenous
Internal calcaneal!
\
Fig. 60. — Cutaneous Nerves on
the posterior aspect of the Lower Limb.
GLUTEAL REGION 161
The cutaneous twigs which come from the anterior primary
divisions of the spinal nerves may be classified under three
headings — (i) those which pass downwards over the crest of
the ilium; (2) those which pass backwards over the insertion
of the gluteus maximus into the fascia lata; (3) those which
turn upwards around the lower margin of the gluteus
maximus.
The nerves which cross the crest of the ilium are — (1)
the iliac branch of the ilio-hypogastric nerve; and (2) the iliac
branch (i.e., the lateral cutaneous branch) of the last dorsal
nerve.
The iliac branch of the ilio-hypogastric fierve pierces the
external oblique muscle close to its insertion into the ilium.
It usually crosses the iliac crest opposite a tubercle which
projects from the outer lip of the crest about two and a half
inches from the anterior superior spine, but it may emerge
at any point between this tubercle and the anterior border of
the iliac origin of the latissimus dorsi. The iliac branch of the
last dorsal nerve pierces the external oblique muscle of the
abdominal wall, a short distance in front of the ilio-hypogastric
branch, at a point situated from one to two inches above
the iliac crest. Both nerves, after crossing the iliac crest,
run downwards in the thick superficial fascia over the upper
part of the gluteus medius, and spread out into a great
number of fine twigs, which ramify over the insertion of the
gluteus maximus. Certain of them reach downwards as far
as the level of the great trochanter.
The nerves which pass backwards over the insertion of
the gluteus maximus are a few small branches of the posterior
division of the external cutaneous nerve of the thigh. They
are found above the level of the great trochanter.
The cutaneous twigs which hook round the lower margin
of the gluteus maximus muscle, to reach the skin over this
region, are a few offsets from the small sciatic nerve and the
perforating cutaneous bra?ich of the fourth sacral ?ierve. The
former appear external to the tuberosity of the ischium, and
are accompanied in some cases by twigs from the sciatic
artery. The latter comes into view internal to the ischial
tuberosity, and is accompanied by small branches of the
inferior hemorrhoidal artery.
These nerves can most readily be found by everting the lower border of
the gluteus maximus ; but in doing this, care must be taken not to injure
VOL. I — 11
1 62 THE LOWER LIMB
the trunk of the small sciatic nerve, as it passes from under cover of the
gluteus maximus and runs vertically down the thigh.
Deep Fascia. — The deep fascia of the gluteal region is
brought into view by removing what remains of the super-
ficial fascia. The fatty tissue should be cleared away not
only from the deep fascia as it is spread over the gluteus
maximus, but also from the area in front of this. In the
latter situation a dense, opaque, pearly white aponeurosis
is by this means exposed. This covers the anterior part
of the gluteus medius, and is firmly attached above to the
crest of the ilium. It stands in marked contrast with the
deep fascia over the gluteus maximus, which is thin and
transparent. Subsequent dissection will show that the
dense fascia over the anterior part of the gluteus medius,
when it reaches the anterior border of the gluteus maximus,
splits into two lamellae which enclose that muscle between
them.
Dissection. — Now proceed to clean the gluteus maximus muscle. If it
is the right limb, begin at the anterior or upper margin of the muscle ; but
if it is the left, commence the dissection at the posterior or lower border.
In undertaking this dissection, the dissector must keep clearly before him
the rules which have already been laid down regarding the cleaning of a
muscle: — (i) render the fibres as tense as possible by rotating the limb
inwards ; (2) remove the fascia in one continuous layer ; (3) always cut in
the direction of the muscular fibres ; (4) define very carefully the borders
of the muscle.
The gluteus maximus is a difficult muscle to clean, the fasciculi are so
exceedingly coarse. To do it well, it is not sufficient to remove the fascia
which covers the muscle, but it is necessary at the same time to follow, for
a short distance, the septa which penetrate between the fasciculi, and to
remove them also. Do not remove the thick opaque fascia which covers
the insertion of the muscle.
The dissector of the left limb, on reaching the anterior margin of the
muscle, will observe that the fascia which he holds in his hand is continuous
with the strong aponeurosis which covers the gluteus medius ; and further,
if he now frees the anterior border of the muscle from subjacent parts, he
will notice that the layer of fascia upon which the gluteus maximus rests is
also continuous with the same aponeurosis. In other words, he will in this
manner be able to satisfy himself that the strong fascia which covers the
anterior part of the gluteus medius splits into two layers to enclose the
gluteus maximus. The small sciatic nerve lies in very close relation to the
deep surface of the muscle, and is apt to be injured in the subsequent steps
of the dissection, unless it is secured at once by everting the lower border
of the muscle.
Gluteus Maximus. — This powerful muscle arises ( 1 ) from a
narrow, rough area on the dorsum ilii, which is included
between the superior curved line and the outer lip of the
GLUTEAL REGION
16
crest; (2) from the sides of the lower two pieces of the
sacrum and the upper three pieces of the coccyx; (3) from
the entire posterior surface of the great sacro-scia'tic ligament :
and (4) slightly from the posterior layer of the lumbar
Quadratus lumborum.
External oblique
Sartorius
Tensor fasciae
Reflected head
^gi^-^i of rectus femoris
Straight head of
rectus femoris
Semimembranosus
Biceps and
semitendinosus
Quadratus femoris
Pyramidalis
Rectus abdominis
Adductor longus
Gracilis
Adductor brevis
Adductor magnus
Fig. 61. — Outer aspect of the Innominate Bone with the Attachments
of the Muscles mapped out.
aponeurosis, at the attachment of the latter to the crest of
the ilium.
From this extensive origin the coarse fasciculi of the
muscle proceed obliquely downwards and forwards towards
the upper portion of the femur, but only a comparatively
small proportion of them receive direct insertion into that
bone. The greater part of the muscle is inserted into the
1— 11 a
i64 THE LOWER LIMB
fascia lata. To be more precise, we may say that the whole
of the fibres belonging to the upper half of the muscle, and
the superficial stratum of fibres of the lower half of the
muscle, are inserted into the fascia lata. The deeper fibres
of the lower half of the muscle, however, are directly attached
to the "gluteal ridge" on the back of the femur {i.e., the
ridge which extends from the great trochanter to the linea
aspera). (Fig. 82, p. 229.) The gluteus maximus is supplied
by the inferior gluteal nerve.
Reflection of the Gluteus Maximus. — This is by no means an easy
dissection. It is best to detach the muscle from its origin and throw it
downwards towards its insertion. It should be dissected completely away
from the various surfaces from which it arises. By this means the general
outline of the pelvis becomes more apparent, and the dissector obtains
distinct bony landmarks which are most useful in enabling him to localise
the various structures he is expected to expose. Let us suppose we are
dealing with the left lower limb. As a preliminary step, the two borders
of the muscle should be freed and the left hand gently insinuated under the
fleshy mass. The muscle must, in the first instance, be detached from the
ilium. When the surface on the dorsum ilii from which it springs is
cleared, we reach the upper margin of the great sciatic notch. Here the
dissector must proceed with caution, because through this pass the gluteal
vessels, branches of which enter the deep surface of the gluteus maximus
muscle. Having secured these, we next detach the muscle from the side of
the sacrum, and the pyriformis muscle emerging from under cover of the
sacrum comes into sight. The muscular fibres may now be raised from the
surface of the great sacro-sciatic ligament and separated from the side of
the coccyx. In doing this, care should be taken to preserve the three sacral
cutaneous nerves intact, in order that they may be subsequently traced to
their origins. As the surface of the great sacro-sciatic ligament is gradually
laid bare, a number of small arteries (the coccygeal branches of the sciatic
artery) will be seen piercing it and immediately sinking into the substance
of the gluteus maximus. These cannot be retained. It is necessary to
sever them in order that the muscle may be freed. The perforating branch
of the fourth sacral nerve, which winds round the lower border of the
gluteus maximus near the coccyx, must also be remembered and traced to
the great sacro-sciatic ligament which it will be seen to pierce.
The gluteus maximus is now completely separated from the parts from
which it arises, but it cannot be thrown downwards towards its insertion.
It is still tied to its place by the blood-vessels and nerves which enter its
deep surface. These are (1) the branches of the superficial division of the
gluteal artery which we have already seen above the level of the pyriformis ;
(2) branches of the sciatic artery and the inferior gluteal nerve below the
level of the pyriformis. The veins may at once be removed, "but the arteries
and nerves must be systematically cleaned as they come into view, and
traced into the substance of the gluteus maximus. Finally, to allow of the
complete reflection of the gluteus maximus, these vessels and nerves must
be cut, and it is advisable to leave in connection with the cut end of each
a small portion of muscle-substance in order that they may be readily
recognised in the further steps of the dissection. The whole muscle may
now be thrown forwards, and after a little dissection an admirable view is
obtained of its insertion. Piercing the lower part of this there will be seen
GLUTEAL REGION 165
a few small twigs of the first perforating artery — a branch of the profunda
femoris.
In the case of the right limb the procedure adopted in reflecting the
gluteus maximus is the same as detailed above, with this exception, that we
begin by detaching it from the coccyx and great sciatic ligament and work
upwards towards the ilium.
Although we have recommended that the gluteus maximus should be
reflected from above downwards, it is right to mention that an equally
instructive view of the subjacent parts may be obtained by detaching it
from its insertion and throwing it upwards towards its origin. The senior
student would do well to adopt this method.
Bursae under cover of the Gluteus Maximus. — Two bursa
are found in relation to the insertion of the gluteus maximus.
The o?ie — a large loose sac — is interposed between the apo-
neurosis, into which the upper part of the muscle is inserted
and the great trochanter of the femur. It allows the bone to
play freely on the deep surface of the muscle. The second
bursa lies immediately below this and in front of the part of
the muscle which is inserted into the gluteal ridge of the
femur. A slight touch of the knife is sufficient to open it,
and then the glistening tendon of the vastus externus comes
into view. The bursal sac intervenes between this tendon
and the aponeurotic insertion of the gluteus maximus.
A third bursa is situated between the gluteus maximus and
the tuber ischii. In all probability this has already been ex-
plored by the dissector of the perineum. It lies over the
inferior aspect of the bony prominence, and is interposed
more between the tough superficial fascia and the bone, than
between the muscle and the bone.
Dissection. — On the second day the dissector undertakes the dissection
of the remaining structures which are displayed by the reflection of the
gluteus maximus. The vessels and nerves which have been partially
exposed in the previous day's dissection must now be followed up towards
the pelvis, and the remaining vessels and nerves, together with the muscles,
must be defined and cleaned by removing the loose areolar tissue which
covers and passes between them.
Parts under cover of the Gluteus Maximus. — As we
proceed from the dorsum ilii downwards towards the tuber
ischii and the back of the thigh, the following muscles may
be recognised: — (1) The gluteus medius lying over the
greater part of the dorsum ilii; (2) the pyriformis, issuing
from the pelvis through the great sacro-sciatic foramen ; ( 3 )
the tendon of the obturator internus coming through the
small sacro-sciatic foramen, with the gemellus superior attached
to its upper border and the gemellus inferior to its lower
66
THE LOWER LIMB
border ; (4) the quadratus femoris passing from the tuber
ischii to the upper end of the femur; (5) the upper border
of the adductor magnus. By separating the contiguous
margins of the gemellus inferior and quadratus femoris
Xerve to quadratus
Inferior gluteal nerve ' Internal pudic nerve
Small sciatic nerve
Superficial part of gluteal artery
Superior gluteal nerve
Deep part of J '
gluteal artery"^
Sciatic artery
Internal pudic artery
Xerve to obturator internus
Gemellus superior
Obturator internus
Gemellus inferior
Great sciatic ligamer
Obturator externus
Quadratus femoris
uber ischii
Nerve to tensor vaginae and
external circumflex artery
Great trochanter
Quadratus femoris
Internal circumflex artery
Adductor magmfs ^US S '■'
\ Adductor magnu
Semimembranosus
Semitendinosus
•Biceps
Fig. 62. — Dissection of the Gluteal Region. The Gluteus Maximus, Gluteus
Medius, and the Quadratus Femoris have been reflected.
widely from each other, and looking into the interval between
them, the tendon of the obturator externus will be revealed as
it passes round the neck of the femur to reach the digital
fossa. By dealing similarly with the adjacent margins of the
quadratus femoris and the adductor magnus, the small
GLUTEAL REGION 167
trochanter of the femur will be exposed. Lastly, the origin
of the hamstring muscles from the tuber ischii and the upper
part of the vastus externus arising from the root of the great
trochanter of the femur on its outer aspect should be noted.
In each interval formed by the adjacent margins of the
muscles exposed, blood-vessels and nerves, or blood-vessels
alone, are to be found.
Before proceeding to the dissection of these, however, it is well that the
student should renew his acquaintance with the skeletal peculiarities of
this region. Let him obtain a dried pelvis with the ligaments in situ, and
study carefully the position and boundaries of the great and small sciatic
notches, and the manner in which they are converted into foramina by the
small and great sacro-sciatic ligaments. Through these foramina important
structures issue from the interior of the pelvis into the gluteal region.
In the interval between the contiguous margins of the
gluteus medius and the pyriformis muscles, the gluteal artery
and the superior gluteal nerve issue from the pelvis through the
great sacro-sciatic foramen. In the interval between the
pyriformis and the gemellus superior, two arteries and six
nerves must be looked for as they emerge through the lower
part of the sacro-sciatic foramen, viz. : —
Arteries,
Nerves,
I 6. Nerve to the quadratus femoris.
The huge great sciatic nerve, together with the sciatic
artery and small sciatic nerve, proceed downwards in the
hollow between the great trochanter of the femur and the
tuber ischii.
In the interval between the gemellus inferior and the
quadratus femoris, the small ascending terminal branch of the
internal circumflex artery will be seen, whilst between the con-
tiguous margins of the quadratus femoris and the adductor
magnus the larger transverse terminal branch of the same artery
makes its appearance.
Inferior Gluteal Nerve (nervus glutseus inferior). — This is
the nerve of supply to the gluteus maximus. It springs from
the sacral plexus, and enters the gluteal region through the
lower part of the great sacro-sciatic foramen. During the
1— lie
f
I.
Sciatic.
I
2.
Internal pudic.
f
I.
Great sciatic.
2.
Small sciatic.
1
1
3"
Internal pudic.
]
4-
Inferior gluteal.
5-
Nerve to the obturator internus.
1 68 THE LOWER LIMB
reflection of the gluteus maximus it has been seen to break
up into numerous twigs which enter the deep surface of
the muscle.
Sciatic Artery (arteria glutaea inferior). — The sciatic artery,
a branch of the internal iliac, issues from the pelvis through
the great sacro-sciatic foramen below the pyriformis muscle,
and proceeds downwards with the sciatic nerves under cover
of the gluteus maximus. Finally reaching the lower border of
that muscle, it is continued as a fine cutaneous twig to the
back of the thigh, in company with the small sciatic nerve.
It gives off numerous branches in the gluteal region. Of
these the large muscular offsets to the gluteus maximus, and
the cutaneous twigs that accompany the branches of the
lesser sciatic nerve which turn round the lower border of that
muscle, have been already studied. The following three
branches remain to be examined: — (i) the coccygeal branch,
which passes inwards between the greater and lesser sacro-
sciatic ligaments to reach the integument and fascia in the
region of the coccyx : a number of twigs derived from this
branch have been previously noticed piercing the greater of
the two ligaments and ending in the gluteus maximus; (2)
comes nervi ischiadici, a minute artery, which runs downwards
on the great sciatic nerve and finally penetrates into its sub-
stance ; (3) the artery to the quadratics fe7noris, which accom-
panies the nerve to that muscle : it will be found lying on
the innominate bone under cover of the great sciatic nerve.
In a well- injected body the anastomosis between the
sciatic artery, the two terminal branches of the internal
circumflex, and the first perforating artery may be made out.
Small Sciatic Nerve (nervus cutaneus femoris posterior). —
This cutaneous nerve arises from the sacral plexus within the
pelvis. After escaping through the great sacro-sciatic foramen
it extends downwards with the sciatic artery under cover of
the gluteus maximus. Reaching the lower border of this
muscle, it proceeds vertically downwards on the back of the
thigh, immediately subjacent to the deep fascia. It will after-
wards be traced to the posterior aspect of the calf of the leg.
In the gluteal region it gives off several cutaneous
branches, viz. — (i) twigs which wind round the lower border
of the gluteus maximus to supply a limited area of the skin of
the buttock: (2) a few twigs to the skin on the inner side of
the thigh ; and (3) the long pudendal nerve of Scemmerring.
GLUTEAL REGION 169
The long pudendal nerve turns inwards round the origin of
the hamstring muscles to reach the perineum.
Great Sciatic Nerve (nervus ischiadicus). — The great sciatic,
the largest nerve in the body, comes from the sacral plexus, and
enters the gluteal region through the lower part of the great
sacro-sciatic foramen. At first it has the form of a flattened
band, but soon it becomes oval or round, as seen in section.
Covered by the gluteus maximus, the great sciatic nerve
traverses the gluteal region in the interval between the great
trochanter of the femur and the tuber ischii. From above
downwards it lies on the innominate bone (at the lower margin
of the great sciatic notch), the tendon of the obturator internus
with its two gemelli muscles, the quadratus femoris, and the
adductor magnus. In this region it does not, as a rule,
give off any branch, but occasionally the nerves to one or
more of the hamstring muscles issue from the main trunk as
high as the level of the quadratus femoris.
The great sciatic nerve frequently escapes from the pelvis in the form of
two trunks (the two divisions into which it divides lower down, viz., the
internal and external popliteal nerves) which enclose between them a portion
of the pyriformis muscle.
Dissection. — The student should flex the knee and raise it on a block in
order to relax the great sciatic nerve. By pulling this great nerve-trunk
outwards, the dissector will expose the nerve to the quadratus femoris
lying directly upon the innominate bone. Internal to this he will find the
pudic vessels and nerve with the nerve to the obturator internus crossing
the spine of the ischium. These structures require to be carefully cleaned.
The twig from the nerve to the obturator internus to the gemellus superior
is especially liable to injury. The dissection will be improved by scraping
off the periosteum from the small area of bone which is in relation to the
above-mentioned vessels and nerves.
Pudic Vessels and Nerve, and the Nerve to the Obturator
Internus. — These structures emerge from the great sacro-
sciatic foramen below the pyriformis, and are only exposed in
the present dissection for a very short part of their course.
They pass out of view by entering the lesser sacro-sciatic
foramen. The ?ierve to the obturator internus is placed most
externally. It lies on the base of the ischial spine, and
furnishes a twig to the gemellus superior. The internal pudic
artery (arteria pudenda interna), with a companion vein on
each side, crosses the tip of the spine. The interna/ pudic
nerve (nervus pudendus) is placed most internally, and lies on
the lesser sacro-sciatic ligament close to its attachment to the
spine. In some cases, however, the pudic nerve unites in a
i 7o THE LOWER LIMB
plexiform manner with the nerve to the obturator internus, so
that the whole, or a part, of it may lie external to the pudic
vessels.
External Rotator Muscles of the Thigh. — Under this head-
ing we include the pyriformis, the obturator internus, the
gemelli, the obturator externus, and the quadratus femoris.
They are all inserted into or in the neighbourhood of the great
trochanter of the femur, and they are applied to the posterior
surface of the capsule of the hip-joint.
The pyriformis arises within the pelvis from the three middle
pieces of the sacrum, and slightly from the upper margin of
the great sciatic notch of the innominate bone. The sacral
origin cannot be seen at present, but the iliac origin should
be made out. After passing through the great sacro-sciatic
foramen, the muscle is directed downwards, outwards, and
forwards. Its fleshy belly rapidly tapers and ends in a rounded
tendon, which crosses the common tendon of the obturator
internus and gemelli, and is inserted into a small impression
on the highest part of the great trochanter of the femur (Fig.
79, p. 222). It is closely adherent to the subjacent obturator
tendon for some distance. The pyriformis is supplied by
branches from the third and fourth sacral nerves.
The obturator internus and gemelli together constitute a
tricipital muscle with one large intra-pelvic belly (obturator
internus), and two small extra-pelvic bellies (gemellus superior
and inferior). The common tendon of this tricipital muscle
is inserted into an impression on the upper part of the great
trochanter of the femur immediately in front of the insertion
of the pyriformis (Fig. 79, p. 222).
The gemellus superior arises from the spine of the ischium
at the upper margin of the lesser sciatic notch. Its fibres
pass outwards along the superior border of the tendon of the
obturator internus, and are inserted obliquely into that tendon.
The gemellus inferior arises from the tuberosity of the ischium
at the lower margin of the lesser sciatic notch, and is in-
serted into the inferior border of the obturator tendon, in
a similar manner to the gemellus superior. Close to their
origins the gemelli meet under cover of the obturator tendon,
and form a fleshy bed, on which it lies ; near the trochanter
the fibres of the gemelli overlap the obturator tendon, and
tend to cover its superficial surface.
The tendon of the obturator internus should be freed from the
GLUTEAL REGION 171
gemelli for some little distance from its point of exit from
the small sacro-sciatic foramen. It may then be divided
and raised from the bed in which it lies. Its deep surface
will be seen to consist of four or five rounded slips separated
by deep grooves or furrows. The surface of the small sciatic
notch on which this tendon glides is coated with smooth
cartilage, which is raised into ridges corresponding to the
grooves on the surface of the tendon. A large synovial bursa
is interposed, which still further facilitates the play of the
tendon round the notch.
The quadratus femoris X\es between the gemellus inferior and
the adductor magnus. It is a flat oblong muscle which arises
from the outer border of the tuber ischii, and proceeds
horizontally outwards to gain insertion into the tubercle of the
quadratus and into a line which extends downwards on the
back of the femur for two inches below this (Fig. 82, p. 229).
Dissection. — The nerve to the quadratus femoris should now be traced
to its termination. This can be done by reflecting the two gemelli muscles
under which it runs. When followed as far as the inferior gemellus, care
should be taken to secure the little twig it gives to that muscle. Lastly,
reflect the quadratus femoris by detaching it from the femur and throwing
it towards the ischial tuberosity. By this dissection not only is the whole
length of the nerve to the quadratus femoris exposed, but also a consider-
able portion of the posterior aspect of the capsule of the hip-joint is laid
bare, and the obturator externus muscle and the termination of the internal
circumflex artery are brought into view.
Nerve to the Quadratus Femoris. — This small nerve runs
vertically downwards on the innominate bone and passes
successively under cover of the following structures : the great
sciatic nerve, the gemellus superior, the tendon of the obturator
internus, the gemellus inferior. It gives the nerve of supply
to the gemellus inferior and a twig to the hip-joint, and ends
by sinking into the deep surface of the quadratus femoris.
Obturator Externus. — This muscle can now be observed
winding round the neck of the femur and finally ending in a
rounded tendon which is implanted into the digital fossa of
the femur (Fig. 82, p. 229). Its origin will be seen at another
time.
Internal Circumflex Artery (arteria circumflexa femoris
medialis). This vessel comes to an end at the upper border
of the adductor magnus by dividing into its ascending and
transverse terminal branches. The ascendmg branch runs
obliquely upwards and outwards under cover of the quadratus
172 THE LOWER LIMB
femoris and upon the surface of the obturator extemus. Its
terminal branches ramify in the neighbourhood of the digital
fossa, where they anastomose with twigs from the sciatic and
gluteal arteries. The transverse branch passes backwards
between the quadratus femoris and the adductor magnus.
It anastomoses with the terminal twig of the middle division
of the external circumflex artery, which in a well-injected
subject will be noticed appearing from midst the fibres of the
vastus extemus at its upper part. An arterial circle is thus
completed around the upper part of the femur which com-
municates above with the sciatic artery and below with the
first perforating artery. This series of inosculations is some-
times spoken of as the crucial anastomosis of the thigh.
Dissection. — The dissector has now examined all the structures in the
gluteal region which lie below the level of the pyriformis. He should, in
the next place, turn his attention to that portion of the dissection which
lies above the level of that muscle. Here are found a number of parts in
close relation to the dorsum ilii. These are the gluteus medius, the gluteus
minimus, and the tensor fasciae femoris muscles, together with the blood-
vessel and nerve which supply them, viz., the gluteal artery and the
superior gluteal nerve.
The gluteus medius muscle is only covered in its hinder part by the
gluteus maximus. In front it is invested by the dense aponeurotic layer
already referred to. This fascia must be removed in order that a satis-
factory view of the muscle may be obtained. It will then become evident
that numerous fleshy fibres arise from the deep surface of the fascia. Care
must be taken not to injure the origin of the tensor fasciae femoris which
overlaps the anterior part of the gluteus medius, and is partially adherent
to it.
Gluteus Medius. — The gluteus medius arises from that part
of the dorsum ilii which is bounded above by the superior
curved line and the anterior four-fifths of the crest of the ilium,
and below by the middle curved line (Fig. 61, p. 163) ; it also
derives fibres from the strong fascia which covers its upper
and anterior part. The fibres converge to form a flattened
band, partly fleshy and partly tendinous, which is inserted
into an oblique line on the outer aspect of the great
trochanter of the femur, as well as into the surface immedi-
ately above it. The gluteus medius muscle is supplied by
the superior gluteal nerve.
Dissection. — The gluteus medius must now be reflected. This dissection
is complicated by the fact that in its upper and anterior part the gluteus
medius is partially blended with the subjacent gluteus minimus and the
tensor fasciae femoris. Begin by rotating the limb well outwards. Then
seizing the gluteus maximus with left hand, pull it well outwards, and
divide the glistening aponeurosis into which it is inserted for two or three
GLUTEAL REGION 173
inches in a downward direction. This will bring very conspicuously into
view the upper part of the vastus externus. Next, grasp the cut edge of
the fascia lata from which the gluteus maximus has been separated, and,
dragging it forcibly outwards, dissect in the interval between it and the
gluteus medius. The tensor fasciae femoris, which is intimately associated
with this portion of the fascia lata, is pulled outwards with it, and the deep
surface of that muscle clothed by a strong deep lamella of fascia comes into
view. Very little dissection is required to expose its nerve of supply — a
branch from the superior gluteal — which emerges from the anterior border
of the gluteus minimus, and sinks into its deep surface. An artery will
also be noticed ramifying on the deep surface of the tensor fascke femoris ;
this is the ascending branch of the external circumflex. Seeing that the
anterior borders of the gluteus medius and gluteus minimus are adherent,
it is well to separate them from behind forward by introducing the fingers
between their posterior borders. When the gluteus medius is completely
isolated, it may be divided about two inches above the great trochanter of
the femur, and the two portions thrown respectively upwards and down-
wards. A small bursa between the muscle and the upper part of the great
trochanter will thus be brought into view, and the exact insertion of the
tendon will be rendered evident. As the upper part of the muscle is raised,
a number of vessels and nerves between it and the gluteus minimus will be
exposed. These must be carefully cleaned and followed to their destina-
tions. They are derived from the gluteal artery and the superior gluteal
nerve.
Gluteal Artery (arteria glutaea superior). — This is a large
vessel which springs from the internal iliac and escapes from
the pelvis through the upper part of the great sacro -sciatic
foramen above the level of the pyriformis.
Immediately after its exit, it divides into a superficial and
a deep division. The superficial divisio?i has been already
seen during the reflection of the gluteus maximus. It is
distributed to the deep surface of that muscle, and is placed
between it and the gluteus medius.
The deep division bifurcates close to its origin into a
superior and an inferior branch ; both of these lie between
the gluteus medius and minimus. The superior bra?ich follows
accurately the middle curved line on the dorsum ilii, and at
the anterior superior spine terminates by anastomosing with
the superficial and deep circumflex iliac arteries, and with
the ascending branch of the external circumflex. The latter
has already been noticed passing upwards under cover of the
tensor fasciae femoris. The inferior branch runs downwards
and forwards towards the great trochanter. It gives twigs
to the two gluteal muscles between which it lies, and some
terminal offsets to the hip-joint.
Superior Gluteal Nerve (nervus gluteus superior). — The
superior gluteal nerve emerges from the pelvis in company
174 THE LOWER LIMB
with the gluteal artery, and passing forwards between the gluteus
medius and minimus, gives branches to both these muscles.
Its terminal branch pierces the anterior fibres of the gluteus
minimus, and ends in the tensor fasciae femoris.
Gluteus Minimus. — This muscle arises from the broad area
on the dorsum ilii, which is included between the middle and
inferior curved lines (Fig. 61, p. 163). The muscular fibres
pass gradually into an aponeurotic tendon, which covers the
superficial surface of the lower part of the muscle. This tendon
as it descends narrows into a flattened band, which is inserted
into a special impression on the anterior aspect of the great
trochanter of the femur (Fig. 79, p. 222). It is intimately
connected at its insertion with the capsule of the hip-joint.
The gluteus minimus is supplied by the superior gluteal
nerve.
Parts under cover of the Gluteus Minimus. — The last
step in the dissection of the gluteal region consists in the
reflection of the gluteus minimus muscle. It must be
detached from its origin and thrown downwards. Three
objects are revealed by this dissection — (1) the capsular liga-
ment of the hip-joint; (2) a bursa which intervenes between
the tendon of the muscle and the great trochanter; (3) the
reflected tendon of the rectus femoris.
The capsular ligame?it will be seen to be only loosely
attached to the posterior aspect of the neck of the femur, but
very firmly to the acetabular brim. The synovial bursa should
be opened and examined. The reflected tendon of the rectus
femoris occupies a groove situated just above the upper
margin of the acetabulum. It is partially concealed by some
fibres of the capsular ligament, which are prolonged upwards
over it. It should be cleaned by repeatedly drawing the point
of the knife over it in a direction parallel to its fibres.
POPLITEAL SPACE.
Before the muscles on the back of the thigh are disturbed,
it is well to dissect the popliteal space. In this way the
boundaries of the space are maintained in position during
the examination of the structures which lie within it
During the dissection of the popliteal space the following
structures are brought into view : —
POPLITEAL SPACE 175
1. Superficial fascia.
2. External saphenous vein.
3. Small sciatic nerve.
4. Popliteal fascia.
Muscles which bound the
space.
Biceps.
Semitendinosus.
Semimembranosus.
Gastrocnemius.
Plantaris.
6. The internal and external popliteal nerves and their branches.
7. The popliteal artery and vein and their branches.
8. A few lymphatic glands.
9. A slender branch from the obturator nerve.
10. The popliteus muscle.
Surface Anatomy. — The space which lies immediately
above the knee-joint, and between the hamstring muscles, is
termed the ham. It is depressed when the knee is flexed,
but forms a slight prominence when the joint is fully ex-
tended. By flexing the knee and pressing deeply into the
interval between the hamstrings, the (injected) popliteal artery
may be distinguished, and its pulsations can usually be dis-
tinguished in this situation in the living subject. With the
limb in the same position, the tendon of the biceps on the
outer side of the space is distinctly seen as it passes down to
its insertion into the head of the fibula. This bony promi-
nence lies behind and a little below the most projecting part
of the outer tuberosity of the tibia, and by pressing deeply
between the fibula and the external condyle of the femur, the
cord-like external lateral ligament can be distinguished. By
slightly flexing the knee-joint and abducting the limb, the
rounded tendon of the adductor magnus may be detected on
the inner side of the limb and traced downwards to the
adductor tubercle. This bony projection is placed on the
femur at the point where the internal supracondylar ridge
joins the upper and back part of the inner tuberosity, and is an
important landmark, inasmuch as it indicates the level or the
plane of junction between the lower epiphysis and the shaft
of the femur. The external popliteal nerve may be felt as it
crosses the outer side of the neck of the fibula, just before it
pierces the peroneus longus muscle. In muscular subjects,
on the upper part of the back of the leg, the two heads of the
gastrocnemius form prominent objects.
The back of the thigh presents a smooth, rounded surface.
In thin subjects indications of the bellies of the hamstring
muscles may be seen.
176 THE LOWER LIMB
Reflection of Skin. — Before beginning the dissection a good-sized block
should be placed under the knee so as to support the limb and render the
muscles which bound the space tense. Incisions — (i) a vertical incision
along the middle line of the limb, beginning about five inches above, and
terminating about four inches below, the bend of the knee ; (2) a transverse
incision at the upper end of the vertical incision ; (3) a transverse incision
at the lower extremity of the vertical incision. The two transverse incisions
should extend almost half-way round the limb.
Two flaps of skin are thus mapped out, and these must be raised and
thrown, the one inwards and the other outwards.
Superficial Fascia — External Saphenous Vein — Branches of
Small Sciatic Nerve. — The fatty layer upon which the skin
rests is now brought into view, and the cutaneous nerves and
vessels must be secured. First look for a small nerve — a
branch of the small sciatic — which passes downwrards over the
space near the middle line, and, when this is found, dissect
out the external saphenous vein. This vessel ascends in the
middle line of the leg, and on tracing it upwards it will be
found to disappear from view by piercing the deep fascia,
and entering the lower part of the popliteal space. The
terminal branch of the small sciatic nerve pierces the popliteal
fascia at the lower part of the space, and here it will be seen
lying close to the external saphenous vein.
In removing the superficial fascia care must be taken of the deep
popliteal fascia, which is somewhat thin.
Popliteal Fascia. — Although thin, the deep fascia possesses
considerable strength, owing to the transverse fibres which
are interwoven amidst its proper aponeurotic fibres. In
removing this fascia the dissector will notice that it is firmly
attached on each side to the tendons of the muscles which
bound the popliteal space. Above, it is continuous with the
fascia lata of the thigh.
Before opening up the popliteal space the dissector is recommended to
read the two following paragraphs, which deal generally with its contents
and boundaries.
Contents of the Space. — The principal objects within the
popliteal space are the popliteal artery and vein with their
branches. They are placed deeply in the space, and in close
contact with each other — the vein being superficial to the
artery throughout. The hvo popliteal nerves — external and
internal — also traverse the space. With the exception of the
small sciatic nerve which descends immediately subjacent to
the deep fascia, the internal popliteal nerve is the most super-
POPLITEAL SPACE 177
ficial structure in the popliteal space. It lies over the popliteal
vessels, and is readily found by separating the adipose tissue
in the middle line of the space. The external popliteal ?ierve
will be exposed by dissecting along the upper and outer
boundary of the space. It lies under shelter of the biceps
muscle. Both of these large nerves give off branches. The
majority of these are easily secured and readily followed. The
articular twigs, however, are very delicate, and great care is
required in their dissection.
In intimate relation to the popliteal artery is the ge?iiculate
branch of the obturator nerve. It descends in close apposition
with the coats of the artery. As the fat is being cleared out
from the space the dissector will not fail to observe some
small lymphatic glands in relation to the great vessels.
Boundaries. — The popliteal space is diamond - shaped.
x\bove and to the outside it is bounded by the biceps muscle ;
whilst above and to the inside are the semitendinosus and the
semimembranosus muscles, the former lying upon the surface ol
the latter. On the inner side of the knee and in front of the
semimembranosus, the gracilis, sartorius, and the tendon of the
adductor magnus, can be exposed. Below, the space is bounded
by the converging heads of the gastrocnemius. In the formation
of the lower and outer boundary, the outer head of the gastro-
cnemius will be seen to be assisted by the small plantaris muscle.
Dissect ion. — In cleaning the muscles which bound the popliteal space
there are certain points to be attended to. In the case of the outer head
of the gastrocnemius, care must be taken not to remove the nervus com-
municans fibidaris, which passes downwards and inwards upon its surface.
In the groove between the heads of this muscle will be seen the nervus com-
municans tibialis. Further, the dissector must not overlook the synovial
bursa which intervenes between the tendon of the semi-membranosus and
the inner head of the gastrocnemius. This bursa sometimes communicates
with a second synovial sac, which will be brought into view by lifting the
inner head of the gastrocnemius from the internal condyle of the femur.
The dissection may be carried in a forward direction on the inner
aspect of the limb a little beyond the inner boundary of the space, in
order to expose the superficial division of the anastomotica artery, the
internal saphenous nerve and vein, and the posterior division of the
internal cutaneous nerve. The internal saphenous nerve accompanied by
the superficial part of the anastomotic artery will be found under cover
of the sartorius. They afterwards come to the surface at its posterior
border. The internal saphenous vein ascends on the surface of that
muscle, whilst the posterior division of the internal cutaneous nerve courses
downwards along the posterior border of the same muscle, and comes to
the surface a short distance behind the internal saphenous nerve. Properly
speaking, these structures belong to the thigh, but it is convenient to secure
them at this stage. They will be afterwards noticed more fully. When
VOL. I — 12
178
THE LOWER LIMB
Small sciatic
the boundaries of the space are thoroughly defined and cleaned, the contents
should be dissected by removing the soft fat which surrounds them.
The dissection of the space should be carried out over the entire area at
the same time. The heads of the gastrocnemius muscle, therefore, should
be well separated from each other. It is here that the dissection becomes
tedious, because the numerous branches of the nerves and vessels to the
muscles on the back of the leg require time and care for their dissection.
The floor of the space must now be cleaned. Scrape the fatty tissue
from the popliteal surface of the femur with the handle of the knife.
It is during this stage of the dissection that the articular branches of
^__ the popliteal artery are
liable to injury, as they
lie in close contact with
the floor. Be especi-
ally careful not to in-
jure the azygos articular
artery which pierces the
posterior ligament of
the knee-joint, and the
superior articular
arteries which wind
round the femur, im-
mediately above the
condyles. The fascia
covering the popliteus
muscle should be left
in position.
Internal popliteal
nerve
Popliteal vein
External
popliteal nerve
Popliteal artery
Superior external
articular artery
Superior internal
articular artery
External
saphenous vein
Nervus com-
municans tibialis
Nervus communi-
cans fibularis
Plantaris
_ Superficial
sural artery
Fig. 63. — Dissection of the Right Popliteal Space.
Popliteal Space as
seen in a Section
through the Frozen
Knee. — The diamond-
shaped space on the
back of the knee-joint
which is brought into
view by dissection,
differs widely from the
condition which is ob-
served when transverse
sections are made
through this part of the
frozen limb (Fig. 64).
Before the integuments
and fasciae are removed all the parts are tightly braced together, and the
popliteal space is merely represented by a small intermuscular interval
between the lower parts of the hamstring muscles. The space in this
condition is rather underan inch wide at its broadest part. The popliteal
artery, therefore, as it traverses the space, is covered by muscles through-
out its whole course, with the exception of a very small part immediately
above the knee-joint.
Floor of the Space. — The floor is formed from above down-
wards by — (1) the popliteal surface of the femur; (2) the
posterior ligament of the knee-joint ; and (3) by the strong
fascia which covers the popliteus muscle.
POPLITEAL SPACE
179
Small Sciatic Nerve (nervus cutaneus femoris posterior). —
The small sciatic nerve enters the popliteal space at its upper
angle, and proceeds downwards immediately subjacent to the
popliteal fascia. It gives one or two twigs through the fascia
to the skin, and finally pierces the fascia in the lower part
of the space. Its terminal twigs are distributed to the skin
over the upper part of the calf of the leg.
Internal Popliteal Nerve. — This nerve enters the popliteal
space by emerging from under cover of the biceps muscle, and
runs vertically downwards so as to bisect the space longi-
Patellar bursa
V. Vastus inter
nus.
S. Sartorius.
S.M. Semimem-
branosus.
G.I. Inner head
of gastro-
cnemius.
G.E. Outer head
of gastro-
cnemius.
Biceps.
B.
Synovial
cavity of
knee-joint
( r \ Popliteal
!jjy« artery
Popliteal vein
Internal pop-
liteal nerve
External pop-
liteal nerve
Fig. 64. — Transverse section through the Popliteal Space of the Right
Lower Limb.
tudinally. It is one of the two terminal branches of the great
sciatic nerve, and it arises about the middle of the thigh.
At the lower, border of the popliteus muscle it becomes
continuous with the posterior tibial nerve. The superficial
position of the internal popliteal nerve has already been
referred to. At first upon the outer side of the popliteal
vessels it crosses them superficially, and in the lower part of
the space it is placed upon their inner side. Its branches may
be classified into cutaneous, muscular, and articular.
The nervus commiuiicans tibialis is its cutaneous branch.
It arises about the middle of the space, and proceeds down-
wards in the furrow between the two heads of the
1—12 a
180 THE LOWER LIMB
gastrocnemius. It will afterwards be seen to unite with the
nervus communicans fibularis, a little below the middle of the
calf of the leg, to form the external saphenous nerve.
The ??iuscular branches supply both heads of the gastro-
cnemius,, the plantaris, the soleus, and the popliteus : they
come off in the lower part of the space. The branch to the
popliteus requires special notice. It arises lower down than
the others, and crosses the superficial surface of the popliteal
artery to reach the outer side of that vessel. It then runs
downwards on the posterior surface of the popliteus muscle,
and gains its deep or anterior surface by winding round its
lower border. This will be better seen when the muscle itself
is dissected.
The articular branches are three in number. They are
given off by the internal popliteal nerve in the upper part
of the space, and they accompany the azygos and the two
internal articular arteries. That which accompanies the
internal inferior articular artery is larger than the other two,
and can be easily discovered as it runs along the upper border
of the popliteus muscle.
External Popliteal Nerve. — This is the smaller of the two
terminal branches of the great sciatic, and it ends on the
outer side of the neck of the fibula by dividing into the
anterior tibial and the musculo - cutaneous. It does not
traverse the entire length of the popliteal space. It runs
downwards and outwards along the inner side of the biceps,
and leaves the space by following closely the tendon of this
muscle. It now lies in the interval between the outer head
of the gastrocnemius and the biceps, and finally turning
forwards round the neck of the fibula, it ends under cover
of the upper part of the peroneus longus. It gives off
cutaneous and articular branches.
The cutaneous branches are two in number, viz., the nervus
communicans fibularis, and one to the skin on the anterior
and outer aspect of. the leg in its upper part. They frequently
take origin by a common trunk. The nervus communicans
■fibularis arises from the external popliteal nerve in the
popliteal space, and is continued downwards over the outer
head of the gastrocnemius. It ultimately unites with the
nervus communicans tibialis, to form the external saphenous
nerve.
The articular branches are three in number. They
,
POPLITEAL SPACE
151
accompany the external articular branches of the popliteal
artery, and the anterior recurrent tibial branch of the anterior
tibial artery. They are of small size, and difficult to dissect.
The recurrent articular nerve springs from the termination of
Semitendinosus
Semimembranosus
Biceps
Internal popliteal _
nerve I '/ffi
Origin of the nervus Iff ■ mS)
communicans
fibularis
Plantaris ??-
External popliteal
nerve
Soleus
Outer head of
gastrocnemius
(cut across)
Nervus communicans
tibialis fi|
Bursa between
capsule of knee and
tendon of semi-
membranosus
Semimembranosus
P werior ligament of
knee-joint (slip from
>emimembranosu>)
Inferior internal
articular ve
Semitendinosus
Internal saphenous vein
Popliteus
Inner head of gastro-
cnemius (cut across)
Deep fascia
- External saphen-
ous vein
Fig. 65. — Popliteal Space. The two heads of the gastrocnemius and portions
of the semimembranosus and semitendinosus have been removed so as to
display more fully the contents of the space.
the external popliteal nerve, and will be dissected at a later
stage.
Popliteal Artery (arteria poplitea). — The popliteal artery
is the terminal part of the great arterial trunk of the lower
limb. It begins at the opening in the adductor magnus,
1—125
152
THE LOWER LIMB
where it is continuous with the femoral artery, and it ends
at the lower border of the popliteus muscle by dividing into
the anterior and posterior tibial arteries. This division is
at present hidden from view by the upper border of the soleus
muscle, but it will be exposed in the dissection of the leg.
The course which the popliteal artery takes through the
popliteal space is not straight. In the first instance it inclines
obliquely downwards and
I / /
outwards, so as to gain the
middle of the space between
the two condyles of the
femur. From this point to
its termination it takes a
vertical course downwards.
Throughout the greater part
of its length it is placed
deeply. In the upper part
of the space it is covered
by the semimembranosus,
but when it gains the interval
between the two condyles,
although it lies deeply in
the fat of the space, it is
simply covered by the in-
teguments and fasciae. This
part of the vessel is very
short, however — not more
than about an inch, — be-
cause it at once passes on-
wards between and beneath
the two heads of the gastro-
cnemius, is crossed by the
plantaris, and finally at its
termination sinks under
cover of the upper border
Adductor magnus
Popliteal vein
Popliteal artery
Superior internal
articular artery
Superior external
articular artery
Inferior external
articular artery
Head of fibula
Inferior internal
articular artery
Popliteus
Soleus
Fig. 66.-
- Popliteal Artery and its
Branches.
of the soleus. Throughout its whole course the popliteal
artery rests upon the floor of the popliteal space. In its upper
part it is separated from the femur by some fatty tissue ; then
it crosses the posterior ligament of the knee-joint ; and lastly
it comes into contact with the fascia covering the popliteus
muscle.
The popliteal vein is placed upon a more superficial plane,
POPLITEAL SPACE 183
and crosses the artery. In the upper part of the space it
is placed upon the outer side of the artery, whereas in the
lower part it is situated upon its inner side. The two vessels,
however, are in close association throughout, and are bound
together by a dense fibrous sheath. The internal popliteal
nerve is superficial to both vessels, and crosses the artery from
without inwards ; in the upper part of the space it lies a short
distance to the outer side of the artery, but in the lowej
part it lies on the inner side.
The branches of the popliteal artery are : —
1. Muscular.
2. Cutaneous.
3. Articular.
The muscular branches consist of an upper and a lower
set. The upper branches are distributed to the hamstring
muscles near their insertions. The lower branches, termed
the sural arteries, end chiefly in the two heads of the
gastrocnemius ; but twigs also go to the soleus and plantaris.
The cutaneous branch, called the superficial sural, usually
arises from one of the sural muscular branches, and supplies
the integument over the upper part of the calf of the leg.
It lies in the groove between the two heads of the gastro-
cnemius with the nervus communicans tibialis.
The articular arteries are five in number, viz., two superior,
two inferior, and one median or azygos.
Superior Articular Arteries. — The two superior articular
arteries spring from the main trunk as it passes between the
condyles of the femur. One proceeds from each side of the
popliteal, and they are called internal and external, according
to the direction which they take. They will be found resting
directly upon the back of the femur, and will be observed to
incline slightly upwards, and then to wind round the bone
immediately above the condyles. The external artery is the
larger of the two. The student is apt to mistake a muscular
branch for one or other of these vessels ; but their close
apposition to the femur should in all cases be sufficient to
distinguish them.
The superior external articular artery (arteria genu superior
lateralis) runs outwards under cover of the biceps, and
disappears from the popliteal space by piercing the external
intermuscular septum and entering the substance of the
crureus muscle. The superior internal articular (arteria genu
1 84 THE LOWER LIMB
superior medialis) proceeds inwards under cover of the
semimembranosus, and leaves the popliteal space by passing
forwards under cover of the tendon of the adductor magnus to
reach the deep surface of the vastus internus muscle.
Inferior Articular Arteries. — The two inferior articuiar
arteries arise from the popliteal as it lies on the lower part
of the posterior ligament of the knee-joint. The inferior
external articular artery (arteria genu inferior lateralis) takes a
transverse course outwards, under cover of the plantaris and
outer head of the gastrocnemius, to gain a point on the outer
side of the knee, immediately above the head of the fibula.
It proceeds onwards under cover of the external lateral liga-
ment of the knee-joint. The i?iferior internal articular artery
(arteria genu inferior medialis) takes an oblique course down-
wards and inwards, under cover of the inner head of the
gastrocnemius, and along the upper border of the popliteus
muscle, to gain the inner side of the tibia below the internal
tuberosity. Here it turns forwards under cover of the internal
lateral ligament of the knee-joint.
Azygos Articular Artery (arteria genu media). — This
springs from the popliteal as it lies upon the posterior liga-
ment of the knee-joint. It pierces this ligament to reach the
synovial membrane.
Popliteal Vein. — The popliteal vein is formed near the
lower border of the popliteus muscle by the union of the
venae comites of the anterior and posterior tibial arteries.
It runs upwards through the popliteal space, and, entering
Hunter's canal through the opening in the adductor magnus,
it becomes the femoral vein. The relations which it presents
to the popliteal artery have already been detailed. In addition
to tributaries corresponding to branches of the artery, it
receives the external saphenous vein, which has been seen
piercing the popliteal fascia to join it. By slitting it open
with the scissors the dissector will see that it possesses
three (sometimes four.) valves in its interior.
Obturator Nerve. — This minute nerve will be found lying
upon the inner side of the popliteal artery. Trace it upwards,
and it will be seen to enter the space by piercing the lower
fibres of the adductor magnus ; follow it downwards, and it
will be observed to enter the knee-joint by penetrating the
posterior ligament.
BACK OF THE THIGH
BACK OF THE THIGH.
The dissection of the back of the thigh must be com-
pleted on the fourth day. The following are the structures
which are brought into view : —
1. Superficial fascia.
2. Cutaneous nerves.
3. Deep fascia.
( Biceps.
1 Semitenchnosus.
4. Muscles, \ c • ,
^ Semimembranosus.
V. Adductor magnus.
„ -vr f Small sciatic.
5. Nerves, - [ r, ....
J y Great sciatic.
6. Arteries, Four perforating.
Reflection of Skin. — A vertical incision must be made in the middle
line of the thigh through the belt of skin which still encircles the limb
posteriorly. The two flaps can then be reflected, the one outwards and
the other inwards.
Superficial Fascia — Cutaneous Nerves. — In the fatty super-
ficial fascia thus brought into view cutaneous twigs from four
sources must be looked for — (1) Along the middle line of the
limb a few minute branches from the small sciatic may be
discovered; (2) Towards the outer side of the thigh some
twigs from the external cutaneous nerve may be detected; (3)
lastly, towards the inner aspect of the limb endeavour to find
some offsets from the internal cutaneous and obturator ?ierves.
Deep Fascia. — On removing the superficial fascia the deep
fascia will be observed to be exceedingly thin. It must now
be turned aside, and in doing this be careful of the trunk of
the small sciatic nerve, which passes down in the middle line
of the limb immediately subjacent to the fascia.
Hamstring Muscles. — The hamstring muscles are three in
number, viz., the biceps, the semitendinosus, and the semi-
membranosus. They stretch from the tuberosity of the
ischium to the upper ends of the tibia and fibula. The
biceps is recognised from its diverging outwards to form the
outer and upper boundary of the popliteal space. The semi-
tendinosus and semimembranosus extend downwards on the
inner side of the posterior aspect of the thigh, the former on
the superficial aspect of the latter.
In cleaning these muscles the dissector should proceed cautiously to
work, otherwise he will injure the arterial and nerve twigs which enter
i86
THE LOWER LIMB
them.
The latter may be easily secured by pulling upwards the upper
part of the great sciatic nerve,
and at the same time gently
separating the muscles with
the fingers.
Biceps Flexor Cruris
(musculus biceps femo-
ris). — The biceps arises
by two heads — a long,
or ischial, and a short,
or femoral, — and is in-
serted chiefly into the
head of the fibula. The
long head arises from the
ischium by a tendon
which is common to it
and the semi-
tendinosus (Fig.
6i,p. 163). This
is implanted into
the inner of the
nternal circumflex artery
Great sciatic nerve
First perforating artery
Adductor magnus
Biceps (divided)
Fig. 67. — Dissection of the Back of the Left Thigh.
Second perforating artery t\VO impreSSlOnS
which mark the
upper part of the
tuber ischii.
Some fibres from
the great sacro-
sciatic ligament
are continued
into it. The short
head arises from
ervus communicans fibularis the back, of the
femur below the
insertion of the
gluteus maxi-
mus, viz., from
the outer lip of
the linea aspera,
from the upper
half of the ex-
Third perforating artery
Internal popliteal nerve
Fourth perforating artery
Opening in adductor mag-
nus and femoral vessels
Obturator nerve (geni-
culate branch)
ternal popliteal nerve
Superior external articular
artery
Superior internal articular
artery
astrocnemius
ternal supracondyloid ridge, and from the external inter-
muscular septum. Its parallel fibres run obliquely downwards
BACK OF THE THIGH
7
and outwards, and join the anterior and inner surface of the
tendon of insertion. This tendon, on the outer aspect of the
knee-joint, is split into an anterior and a posterior part by the
external lateral ligament. Both are inserted into the head of
the fibula in front of the styloid process, but the posterior
slip gives an aponeurotic extension to the fascia of the leg,
whilst the anterior part gives off a slip (in some cases strong,
but generally feeble) to the adjacent part of the outer
tuberosity of the tibia.
Semitendinosus. — This muscle arises from the inner impres-
External lateral
ligament of knee
Sartorius
Gracilis
Semitendinosus
Fig. 68. — Front aspect of Upper Portions of Bones of Leg with
Attachments of Muscles mapped out.
sion on the upper part of the tuberosity of the ischium by a
tendon common to it and the long head of the biceps, and also
by fleshy fibres directly from the bone (Fig. 61, p. 163). A
narrow tendinous intersection appears on the posterior surface
of the muscle about the middle of the thigh, and is directed
obliquely downwards and outwards. The muscular belly ends
in the lower third of the thigh, in a long cylindrical tendon
which passes downwards on the semimembranosus muscle. On
the inner side of the knee the tendon bends forwards, crosses
the internal lateral ligament of the knee-joint, and, becoming
flattened, is inserted into the upper part of the internal
surface of the shaft of the tibia, near the anterior border of
that bone, and immediately below the tendon of the gracilis.
1 88 THE LOWER LIMB
From its lower border aponeurotic fibres pass into the deep
fascia of the leg ; its upper border is adherent to the gracilis
for about half an inch from its insertion, and both tendons
are concealed by the expanded insertion of the sartorius. A
synovial bursa lies between the three tendons and the internal
lateral ligament of the knee-joint.
Semimembranosus. — The semimembranosus muscle arises
from the outer impression on the upper part of the tuberosity
of the ischium (Fig. 61, p. 163). The tendon of origin
is broad at its attachment to the bone, and narrows as
it passes inwards beneath the origin of the biceps ; it then
expands again, and, passing downwards and inwards under
cover of the semitendinosus, is folded in such a manner
as to form a groove, in which the latter muscle lies. The
tendon of insertion is chiefly inserted into the groove on the
back of the internal tuberosity of the tibia, under cover of the
internal lateral ligament of the knee-joint. Three additional
attachments, however, require to be noted. These are
effected by aponeurotic extensions from the tendon of in-
sertion— (1) to the back of the knee-joint, forming a consider-
able part of the posterior ligament; (2) to the surface of the
popliteus muscle, which is covered by the expansion; and (3)
to the internal lateral ligament of the knee-joint.
Great Sciatic Nerve (nervus ischiadicus). — This large nerve
commences at the lower border of the great sacro-sciatic fora-
men, and usually terminates about the middle of the thigh by
dividing into the internal and external popliteal nerves. Its
relations in the gluteal region have already been studied. In
the thigh it lies on the posterior surface of the adductor
magnus muscle, and is covered by the long head of the
biceps. It gives branches to both heads of the biceps, to
the semitendinosus, to the semimembranosus, and to the
adductor magnus ; the branches to the two last-named muscles
arise by a common trunk. In a few cases it may be observed
to give off a long articular twig, which enters the popliteal
space and takes the place of the superior external articular
nerve which, as a rule, comes from the external popliteal
nerve.
Perforating Arteries (arteriae perforantes). — Four per-
forating arteries, branches of the profunda femoris, will be
found emerging from the surface of the adductor magnus muscle
close to the linea aspera of the femur. They are called first,
BACK OF THE THIGH 189
second, third, and fourth, according to the level at which they
appear from above downwards. The fourth is the terminal
branch of the profunda artery of the thigh, and it makes its
appearance about an inch above the opening in the adductor
magnus muscle through which the popliteal artery enters the
popliteal space. The perforating arteries and their branches
must be thoroughly cleaned, together with the apertures in
the adductor magnus through which they pass. It will then
be seen that they do not pierce the fleshy substance of the
muscle. Prepared for each is a tendinous archway, and they
reach the back of the thigh by passing between these and the
linea aspera, to which the piers of the various arches are
attached.
These openings lie in the same line, and are in all respects
analogous to the large opening in the adductor magnus muscle
for the popliteal artery. The result obtained is the same
in each case. When the muscle contracts, the vessels are
protected from pressure.
Emerging from the tendinous arches the perforating
arteries wind round the back of the femur so as to gain its
outer aspect, and reach the vastus externus in which they
end. In this part of their course they pierce the short head
of the biceps. The highest member of the series, which lies
above the level of the femoral attachment of the biceps,
pierces, as we have already seen, the insertion of the gluteus
maximus.
Dissection. — To bring the adductor magnus muscle more fully into view,
and at the same time to facilitate the process of cleaning its radiating
fibres, it is well to reflect the hamstring muscles from their origins. First
divide the conjoined tendon of the biceps and semitendinosus. This
displays the precise origin of the semimembranosus, and when the
dissector has again examined this under the present more advantageous
circumstances, he should divide it also.
Anastomosis on the Posterior Aspect of the Limb. — In a
well-injected subject a chain of anastomoses, in which every
link is complete, can be traced from the gluteal region down
the back of the thigh to the popliteal space. The present is
the best time to study this. Commencing above, we find the
gluteal artery anastomosing with the sciatic, and the sciatic
with the internal circumflex. In the back of the thigh this
chain is carried downwards by the internal and external
circumflex arteries anastomosing with the first perforating, each
i9o THE LOWER LIMB
perforating artery inosculating with the one below it, and
lastly the lower perforating arteries effecting junctions with
the muscular branches which the popliteal artery gives to the
hamstrings.
FRONT OF THE THIGH.
The body is now turned round so as to lie on its back.
The pelvis is supported by two blocks, and the lower limbs
are stretched out at full length upon the table (Fig. 5, p. 15).
Surface Anatomy. — The anterior superior spine of the
ilium should in the first place be recognised, and the crest
of the ilium traced as it proceeds outwards and backwards
from this. The boundary line between the front of the thigh
and the region of the abdomen is formed by Poupart's liga-
ment, which stretches from the anterior superior spine of the
ilium to the spine of the pubis. Its course and position are
marked on the surface by a faint groove. By running the
finger along this when the thigh is fully extended the liga-
ment may be felt. At its inner end the spine of the pubis
should be determined, and then the finger may be carried
inwards on the crest of the pubis to the symphysis pubis.
The rami of the pubis and ischium, leading downwards and
backwards to the tuberosity of the ischium, constitute the
upper boundary of the thigh on its internal aspect, and their
relation to the surface must therefore be ascertained. Below
Poupart's ligament in the extended position of the thigh,
there is a faint depression corresponding in position to
Scarpa's triangle.
In the dissection of the front of the thigh, the skin is also
reflected from the anterior aspect of the knee. The dis-
sector should therefore take the present opportunity of study-
ing the surface anatomy of this articulation. The patella
forms a marked prominence in front of the joint. When
the limb is extended' and the extensor muscles on the front
of the thigh are relaxed, the patella will be found to be
freely movable when grasped between the finger and thumb.
Note its change of position when the leg is flexed on the
thigh at the knee-joint. It passes downwards, and comes to
lie in front of the interval between the femur and tibia. The
patellar surface of the femur can now be felt. The powerful
FRONT OF THE THICxH 191
ligamentum patellae which passes vertically downwards from
the patella to the anterior tuberosity of the tibia can be easily
distinguished. The massive condyles of the femur should
next be studied and compared. The internal condyle is the
more prominent of the two, and immediately above its
tuberosity the adductor tubercle can be recognised. The
articular interval between the condyles of the femur and the
head of the tibia is not visible on the surface, but it can
readily be felt by the finger. The three tuberosities of the
tibia should likewise be studied, and the position of the head
of the fibula on the posterior and lower aspect of the external
tuberosity ascertained.
Superficial Dissection.
This dissection comprises the examination of the following
parts : —
1. Superficial fascia.
2. Internal saphenous vein, and its several tributaries.
( Superficial pudic.
3. Arteries, - Superficial epigastric.
\ Superficial circumflex iliac.
4. Lymphatic glands and vessels.
5. The saphenous opening.
6. Cutaneous nerves.
7. The fascia lata.
8. The bursa patellae.
Reflection of Skin. — Incisions. — (1) From the anterior superior spine of
the ilium along the line of Poupart's ligament to the symphysis pubis : 2
from the inner extremity of this line downwards, round the scrotum, and
along the inner aspect of the thigh for four inches ; (3) from the lower
extremity of this vertical incision transversely outwards, across the front of
the thigh, to the outer aspect of the limb (Fig. 5, p. 15).
The quadrilateral flap of skin thus traced out must be raised carefully
from the subjacent superficial fascia and turned outwards.
Superficial Fascia. — The fatty superficial fascia which is
now exposed is continuous with the corresponding layer on
the front of the abdomen, and it is regarded by some
anatomists as being composed of two layers. This subdivi-
sion we consider needless and artificial. In the lower part of
the abdominal wall, above Poupart's ligament, it is true the^
superficial fascia presents two distinct stmtQ — one a fatty
layer continuous over Poupart's ligament, with the superficial
fascia on the front of the thigh, and sometimes termed the
i94 THE LOWER LIMB
The superficial epigastric turns upwards and leaves the thigh
by crossing Poupart's ligament about its middle. It is dis-
tributed chiefly to the skin on the front of the abdomen.
The superficial circumflex iliac is very minute, and courses
upwards and outwards along Poupart's ligament towards the
anterior superior spine of the ilium.
The veins which accompany these arteries converge to-
wards the saphenous opening and join the internal saphenous
vein near its termination.
Lymphatic Glands and Vessels. — The disposition of the
lymphatic glands into two groups will now be evident — an
upper inguinal group along the line of Poupart's ligament, kn-
mediately below the attachment of Scarpa's fascia to the fascia
lata, and a lower femoral group, which extends for a short way
down the thigh along the line of the internal saphenous vein.
In a spare subject, or, better still, in a dropsical subject, the
general arrangement of the lymphatic vessels may also be
made out. To the femoral group of glands proceed the vessels
of the lower limb : to the inguinal glands go the lymphatic
vessels from the genitals, perineum, and the surface of the
abdomen. These are termed the afferent vessels. In addition
to these, numerous vessels pass between the various glands
and connect them with each other. The lymphatic vessels
which lead the lymph away from the glands are called the
efferent vessels. A large number of these pass through the
saphenous opening, others pierce the deep fascia. They join
the glands which lie in relation to the femoral and external
iliac arteries.
Dissection. — It requires an experienced dissector to display in a satisfactory
manner the saphenous opening, or, in other words, the aperture in the deep
fascia through which the saphenous vein passes to join the femoral vein.
Begin by removing the lymphatic glands. In doing this bear in mind that
the crura/ branch of the genito-crural nerve pierces the fascia lata in the
middle line of the thigh about an inch or so below Poupart's ligament.
Take care also of the two divisions of the middle cutaneous fierve, which
make their appearance in the same line about three inches below Poupart's
ligament.
To define the saphenous opening, the dissector should commence by
cautiously removing the superficial fascia from the fascia lata over the
upper parts of the adductor longus and pectineus muscles. The deep fascia
at this point is called the pubic portion of the fascia lata, and as it is cleaned,
from within outwards, it will be observed to recede gradually from the
surface and to be continued behind the femoral vessels. The clearly defined
inferior cornu of the saphenous opening will now be brought into view,
curving under the internal saphenous vein, and blending with the pubic
portion of the fascia lata. The cribriform fascia, a thin and imperfect layer
FRONT OF THE THIGH T95
which is spread over the aperture, must be removed so as to display the
outer boundary of the opening. In doing this take care not to injure the
subjacent sheath of the femoral vessels to which it is more or less firmly
attached. This dissection is artificial, seeing that the cribriform fascia is
merely a continuation inwards of the outer lip of the opening. The outer
boundary is usually very much broken up by the superficial branches of the
femoral artery which pierce it, and its definition is a matter of some
difficulty. In a spare subject, however, the line of demarcation between
the cribriform fascia and the iliac portion of the fascia lata may be
distinguished. The name "iliac portion" is given to that part of the
fascia lata which lies external to the opening.
Saphenous Opening. — This is the aperture in the deep
fascia through which the saphenous vein passes to effect its
junction with the femoral vein. A thin fascia, called the
cribriform fascia, is spread over the opening. This fascia
has received the name of "cribriform," because it is pierced
by the saphenous vein and by numerous lymphatic vessels.
Some difference of opinion exists as to what this fascia
really is. It is regarded by some as being a part of the
superficial fascia, but it is more correct to look upon it as
being a thin layer of fascia lata carried over the opening, or,
in other words, a prolongation inwards of the outer margin of
the opening.
The importance of the saphenous opening consists in the
fact that it is through it that a femoral hernia makes its way
to the surface. It is oval in shape and not more than
half an inch in width ; but it is at least one and a half inches
long. Its inner boundary is formed by the receding pubic
portion of the fascia lata, and lies on a deeper plane than the
outer boundary. The outer boundary is crescentic, and is
known as the falciform edge of the opening. It is formed by
the iliac portion of the fascia lata. The inferior cornu of the
falciform edge curves inwards under the saphenous vein, in
the form of a very distinct process which joins the pubic part
of the fascia lata. The superior cornu (sometimes called Hey's
ligament), not so well defined, sweeps inwards in front of the
upper part of the subjacent femoral sheath, and joins the front
of Gimbernat's ligament.
Reflection of Skin. — The next step in the dissection consists in
reflecting the skin from the lower two-thirds of the front of the thigh, and
also from the anterior aspect of the knee. This is effected by extending
the vertical incision, which has already been made upon the inner aspect
of the thigh downwards to the internal tuberosity of the tibia, and then
carrying a transverse incision from the lower end of the vertical cut outwards
over the front of the leg to its outer aspect. In raising the skin from the
196 THE LOWER LIMB
front of the knee take care not to injure the patellar plexus of nerves and
the patellar bursa. In reflecting the integument from this extensive area,
we have two objects in view — Firstly, the dissection of the cutaneous nerves
and vessels of the thigh ; and secondly, the examination of the entire extent
of the fascia lata.
Internal Saphenous Vein (vena saphena magna). — The
internal saphenous vein should be dissected in the superficial
fascia to the lower limit of the area from which the skin has
been reflected. It is the largest superficial vein of the lower
limb. Taking origin on the dorsum of the foot, it extends
upwards on the leg. On the inner side of the knee it will
be seen to be placed very far back. As it reaches the thigh
it inclines somewhat forwards, and runs upwards on the front
and inner aspect of the limb to the saphenous opening in
the fascia lata. Through this aperture it passes to join the
femoral vein.
In its course along the thigh it receives several tributaries.
Two of these are of large size, viz., an anterior branch, which
collects the blood from the front and outer aspects of the limb,
and a posterior bra?ich, which performs a similar office for the
posterior and inner aspects of the thigh. They both enter the
internal saphenous vein near its termination. In addition to
these, the three small veins corresponding to the superficial
inguinal arteries converge towards the saphenous opening, and
join the saphenous trunk as it disappears through it.
Cutaneous Nerves. — The cutaneous nerves are now to
be looked for in the superficial fascia. The main stems
are six in number, and are derived from two sources. Three
come directly from the lumbar plexus, and three are branches
of the anterior crural nerve : —
( Ilio-inguinal.
From lumbar plexus, -J Crural branch of genito-crural.
( External cutaneous.
( Middle cutaneous.
From anterior crural, -I Internal cutaneous.
\ Long saphenous.
The ilio-inguinal nerve will be found as it escapes from the
external abdominal ring in company with the spermatic cord.
Its branches go for the most part to the scrotum, but some
are distributed to the skin on the upper and inner side of
the thigh.
The crural bra?ich of the genito-crural nerve pierces the
ascia a little way below Poupart's ligament, and to the outer
FRONT OF THE THIGH 197
side of the femoral artery. With a little care a communication
between this nerve and the middle cutaneous may be made
out. It supplies a limited area of skin on the upper part of
the front of the thigh.
The external cutaneous nerve is distributed on the outer
aspect of the thigh. It pierces the deep fascia in two parts.
Of these, one — the posterior division — appears about two
inches below the anterior superior iliac spine, and proceeds
backwards and downwards. Some twigs of this nerve may be
followed to the lower part of the gluteal region. The anterior
division comes to the surface about two inches lower down.
It is the larger of the two, and has a wide area of distribution.
It extends as low as the knee-joint. Previous to its division
the external cutaneous nerve lies in a prominent ridge of
the fascia lata, which descends vertically from the anterior
superior spine of the ilium. This may be split up to expose it.
The middle cutaneous nerve pierces the fascia lata in the
middle line of the thigh about three or four inches below
Poupart's ligament. It usually appears as two nerves which
perforate the fascia at two points a short distance apart from
each other. Both branches extend downwards as low as the
knee, which they reach on its inner aspect.
The internal cutaneous nerve, following the example of the
external cutaneous and the middle cutaneous, divides into two
portions — an anterior and a posterior — which perforate the
deep fascia on the inner aspect of the limb, and at some
distance apart from each other. The a?iterior division makes
its appearance through the fascia lata in the lower third of
the thigh, in front of the internal saphenous vein. It
descends towards the knee, and its terminal branches turn
forwards and outwards in front of the patella. The posterior
division reaches the surface on the inner side of the knee,
behind the long saphenous nerve, and proceeds downwards
to supply the integument on the inner side of the upper
part of the leg. But the main stem of the internal cutaneous
nerve, before it divides, likewise sends a few twigs through
the fascia lata to reach the skin on the upper and inner
aspect of the thigh. These make their appearance along
the line of the internal saphenous vein.
The long saphenous nerve becomes cutaneous on the
inner side of the knee by perforating the fascia between
the tendons of the sartorius and gracilis muscles. The
1— 13 a
ioS
THE LOWER LIMB
guide to it is the superficial
artery which descends alongside
External cutaneous--
Ilioinguinal
Crural branch of
genito-crural
Branch from internal
cutaneous
Middle cutaneous-
Internal cutaneous —
[Ml
Internal_
saphenous vein
Anterior part of.
internal cutaneous
Patellar branch of.
long saphenous
m\
Internal
saphenous vein"
Long saphenous.
m
Musculo-cutaneous-
branch of the anastomotic
of it. It follows the course
of the internal saphenous
vein into the leg. Before it
pierces the fascia it gives
off a patellar branch.
The patellar bra?ich of the
long saphenous nerve pierces
the sartorius muscle and the
fascia lata on the inner side
of the knee, and turns out-
wards and forwards in front
of the joint, below the level
of the patella.
Four of the cutaneous
nerves of the thigh have
been noticed to send twigs
to the skin over the knee-
joint, viz., the anterior divi-
sion of the external cutane-
ous, the middle cutaneous,
the anterior division of the
internal cutaneous, and the
long saphenous. These
nerves communicate with
each other and form an
interlacement which is situ-
ated over the patella, the
ligamentum patellae, and
upper part of the tibia. It
is termed the patellar plexus.
On the inner side of the thigh
two minute cutaneous nerve twigs
sometimes make their appearance
which do not belong to any of
Anterior tibia] t^stS^! lne above main cutaneous trunks.
One appears below the ilio-inguinal
nerve, and is a twig from the long
Fig. 70. — Cutaneous Nerves on the Front pudendal branch of the small
of the Lower Limb. sciatic ; the other pierces the deep
fascia half-way down the inner
side of the thigh, and comes from the obturator nerve.
Fascia Lata. — This is the name which is given to that
FRONT OF THE THIGH 199
portion of the general aponeurotic investment of the lower
limb which clothes, and preserves the figure of, the thigh. It
should be carefully cleaned by removing the remains of the
superficial fascia. This being done, the dissector will be struck
with the marked difference in strength which it shows on
the outer and inner aspects of the thigh. Externally it is so
dense and strong that it appears to be more tendinous than
aponeurotic in its character. The reason of this is, that the
tensor fasciae femoris muscle and the greater portion of the
gluteus maximus are inserted into it upon this side of the
limb. The strong band thus formed goes under the name
of the ilio-tibial band, from its being attached above to the
crest of the ilium, and below, to the outer tuberosity of the
tibia and to the head of the fibula. It acts as a powerful
brace on the outer aspect of the limb, which in the erect
posture helps to steady the pelvis, and at the same time
keep the knee-joint firmly extended. Internally, the fascia
lata is so exceedingly delicate and thin that the subjacent
muscular fibres shine through it, and it is very apt to be
removed with the superficial fascia unless care be exercised
in the dissection.
Superiorly, around the root of the limb, the fascia lata
is attached to Poupart's ligament and the bones of the pelvis. '
Behind, it is continuous with the gluteal aponeurosis, and
through this it is fixed to the coccyx, sacrum, and crest of the
ilium. On the outer side, it is attached to the crest of the
ilium ; and on the inner side, to the body of the pubis, the
side of the pubic arch, and to the tuberosity of the ischium.
In front, its upper attachment is complicated by the presence
of the saphenous opening. This aperture separates the
fascia lata into an outer or iliac portion and an inner or
pubic portion. This subdivision only extends downwards to
the lower border of the saphenous opening. The iliac portion
is attached along the whole length of Poupart's ligament. Its
inner crescentic margin bounds the saphenous opening
externally and forms its falciform edge. The superior cornu
of this edge blends with Gimbernat's ligament, whilst its
inferior cornu joins the pubic portion of the fascia lata. The
pubic portion clothes the upper portions of the adductor longus
and pectineus muscles. It recedes from the surface as it is
traced outwards and passes behind the femoral vessels. In
this situation it forms the posterior wall of the femoral sheath
200
THE LOWER LIMB
and is continuous above with the fascia iliaca l which covers
the ilio-psoas muscle in the iliac fossa. To the inner side of
the femoral vessels the pubic portion of the fascia lata is
attached above to the ilio-pectineal line of the pubic bone.
The cribriform fascia, as previously stated, is to be regarded as
a thin piece of the fascia lata, stretched across the saphenous
opening. Externally, it is continuous with the falciform edge
of the iliac portion of the fascia ; internally, it blends with the
front of the pubic portion.
In the neighbourhood of the knee the fascia lata is
continuous behind with the popliteal fascia, whilst on the
lateral and front aspects of the
joint it is attached to the various
bony prominences and to the
different tendons in this locality.
Here it helps to strengthen and
support the capsular ligament of
the knee-joint.
Intermuscular Septa. — But the
fascia lata has other offices to
perform besides that of forming
a continuous investment for the
Fig. 71. — Diagram to show the . . . c .
arrangement of the three inter- thlgh- *r0m everY Part of lts
muscular septa and the three deep surface processes pass off
osteo- fascial compartments of wnich penetrate the limb and
constitute sheaths for the muscles
and other structures which com-
pose it. Three of these are
especially strong, and form distinct
septa or partitions which reach the femur and are attached
to the linea aspera on its posterior aspect. These partitions
are termed the intermuscular septa, and are so disposed that
they intervene between the three great groups of muscles in
this region. The external intermuscular septum is placed be-
tween the extensor muscles in the front of the thigh and the
hamstring muscles on the posterior aspect of the thigh ; the
internal intermuscular septum intervenes between the extensor
muscles and the adductor muscles on the inner aspect of the
1 The dissector must keep clearly before him the distinction between the
fascia iliaca and the iliac portion of the fascia lata. The former is a part
of the general aponeurotic lining of the abdominal cavity ; the latter is a
part of the aponeurotic investment of the thigh.
a. Internal intermuscular septum.
/'. Posterior intermuscular septum.
t . External intermuscular septum.
FRONT OF THE THIGH 201
limb; whilst the posterior intermuscular septum, weak and incon-
spicuous in comparison with the other two, is interposed
between the adductor and the hamstring muscles. These
partitions will be disclosed in the subsequent dissection. In
the meantime, merely observe that the internal and the
external septa show on the surface of the fascia in the lower
part of the thigh as white lines. The thigh is in this manner
divided into three osteo-fascial compartments, viz., an anterior,
containing the extensor muscles and the anterior crural nerve ;
a posterior, holding the hamstrings and the great sciatic nerve ;
and an internal, for the adductors with the obturator nerve
(Fig. 71).
Patellar Bursa. — This is situated upon the superficial
aspect of the patella. Pinch up the fascia lata as it passes
over this bone with the forceps, and make a transverse incision
through the wall of the sac large enough to admit the finger.
The bursa will then be seen to extend downwards for a short
distance upon the ligamentum patellar It is usually inter-
sected by fibrous bands and cords.
Deep Dissection.
In this dissection, the following parts require to be
examined : —
1. The femoral sheath.
2. Crural branch of genito-crural nerve.
3. External cutaneous nerve.
4. Sartorius muscle.
5. Anterior crural nerve and its branches.
6. Femoral vessels and their branches.
7. Ilio-psoas muscle.
C Rectus femoris.
o r\ a • <. Vastus interims,
b. ( madnceps extensor, < ~ , ,
c t Crureus and subcrureus.
^ Vastus externus.
9. Tensor fascia: femoris muscle.
10. Deep layer of the ilio-tibial band of fascia lata.
11. The external and internal intermuscular septa.
Poupart's Ligament — Gimbernat's Ligament. — Although,
properly speaking, both of these ligaments belong more to
the abdominal wall than the thigh, it is essential that the
dissector should obtain some knowledge of their connections
before he proceeds further with the dissection. Pouparfs
202
THE LOWER LIMB
ligament is merely the thickened lower border of the apo-
neurosis of the external oblique muscle of the abdominal wall
folded backwards upon itself. It thus presents a rounded
surface towards the thigh, and a grooved surface towards the
abdomen. By its outer extremity it is fixed to the anterior
superior spine of the ilium. Internally, it has a double
attachment, viz. — (i) to the spine of the pubis; (2) through
Sheath of rectus
Aponeurosis of external oblique
i h
Intercolumnar
fibres
Poupart's
ligament
L.xternal abdominal
ring
—Triangular fascia
.SB Gimbernat's ligament
Fig. 72. — Dissection to show the connections of Poupart's ligament.
the medium of Gimbernat's ligament to the inner part of the
ilio-pectineal line. Poupart's ligament pursues an oblique
course between its .iliac and pubic attachments, and at the
same time describes a gentle curve, the convexity of which
is turned downwards. By its lower border it affords attach-
ment to the fascia lata, and when this is divided it loses its
curved direction.
Gimbernaf s ligament is a small triangular piece of apo-
neurotic fascia which occupies the interval between the inner
part of Poupart's ligament and the inner inch of the ilio-
FRONT OF THE THIGH 203
pectineal line — being attached by its margins to both. Its
base, which looks outwards, is sharp, crescentic, and free, and
abuts against the femoral sheath. Gimbernat's ligament
occupies a very oblique plane ; its femoral surface looks
downwards and outwards, whilst its abdominal surface is
directed upwards and inwards.
Dissection. — The exposure of the femoral sheath is the next step in the
dissection of the thigh. To attain this object the iliac portion of the fascia
lata must be partially reflected. Divide the superior horn of the outer
crescentic margin of the saphenous opening, and then carry the knife
outwards along the lower border of Poupart's ligament, so as to sever the
attachment of the fascia lata to this thickened band. This incision should
extend to within an inch of the anterior superior spine of the ilium. The
piece of fascia marked out by the incision above, and by the outer free
margin of the saphenous opening internally, must be carefully raised from
the subjacent femoral sheath and thrown downwards and outwards. On
the removal of a little loose fat, the femoral sheath will be brought into view
as it enters the thigh under Poupart's ligament. Isolate it carefully from
adjacent and surrounding parts, by carrying the handle of the knife gently
round it — insinuating it first between the sheath and Poupart's ligament,
then between the sheath and Gimbernat's ligament, which lies internal to it.
Femoral Sheath. — The funnel-shaped appearance of the
femoral sheath will now be apparent — the wide mouth of the
membranous tube being directed upwards into the abdomen,
and the narrow inferior part gradually closing upon the
vessels, and fusing with their coats about the level of the
lower limit of the saphenous opening. Whilst it presents this
appearance, however, it should be noticed that its sides do
not slope equally towards each other. The outer side of the
sheath indeed is nearly vertical in its direction, whilst the
inner wall proceeds very obliquely from above downwards
and outwards. If the dissection has been successfully per-
formed, the crural branch of the ge?rito-crural nerve should be
seen piercing the outer wall of the sheath, whilst the internal
saphenous vein, and some lymphatic vessels, perforate its
anterior and inner walls. Further, if the subject be spare,
and the fascial well marked, the dissector will in all probability
notice that the anterior wall of the sheath in its upper part
is strengthened by some transverse fibres which pursue an
arched course across it. To these fibres the name of deep
crural arch is given, in contradistinction to the term superficial
crural arch, which is frequently applied to Poupart's ligament.
In favourable circumstances the deep crural arch may be
observed to spring from the under surface of Poupart's liga-
ment about its middle. After traversing the front of the
2o4 THE LOWER LIMB
sheath the band expands somewhat, and is attached by its
inner extremity to the ilio-pectineal line of the pubic bone
behind Gimbernat's ligament.
Constitution of the Femoral Sheath. — The source from
which the femoral sheath is derived, and the manner in
which it is formed, must next be considered. This entails
the study of some of the structures concerned in the construc-
tion of the abdominal wall. Unfortunately it is not likely
that at this period the dissection of the abdomen is in a
sufficiently advanced state for their examination. A small
portion of the inner part of the interval between Poupart's
ligament and the portion of the innominate bone over which
it stretches is filled up by Gimbernat's ligament. Immediately
to the outer side of this the femoral vessels, enclosed within
the femoral sheath, enter the thigh from the abdominal cavity,
whilst to the outer side of these the interval is occupied by
the ilio-psoas muscle. Three nerves also find their way into
the thigh through this interval, viz., the crural branch of the
genito-crural, which passes downwards in the femoral sheath ;
the anterior crural nerve, which occupies the interval between
the psoas and iliacus muscles ; and the external cutaneous
nerve, which runs behind Poupart's ligament close to its iliac
attachment.
The arrangement of the aponeurotic lining of the
abdominal cavity with reference to this interval of communi-
cation between abdomen and thigh also requires attention.
The lower part of the posterior wall of the abdomen, immedi-
ately above the thigh, is formed by the iliacus and psoas
muscles. These are covered by that part of the aponeurotic
lining of the abdomen which receives the name of the fascia
iliaca. The anterior wall of the abdomen is lined in like
manner by a portion of the general lining, termed the fascia
transversalis. To the outer side of the femoral vessels these
two fascial layers become continuous with each other, and at
the same time are attached to the back of Poupart's ligament.
It is behind this that the ilio-psoas, the anterior crural nerve,
and the external cutaneous nerve, are carried downwards into
the thigh. But the external iliac vessels (the femoral vessels
in the thigh) with the genito-crural nerve lie in front of the
fascia iliaca, or, in other words, within the fascial lining of
the abdomen, and, as they proceed downwards behind
Poupart's ligament, they carry with them a funnel-shaped pro-
FRONT OF THE THIGH
205
longation of the lining. This, then, is the femoral sheath,
and the dissector will now readily understand that the front
wall of the sheath is formed of fascia transversal's from the
anterior wall of the abdomen above Poupart's ligament, while
the posterior wall is formed of fascia iliaca, prolonged down-
wards from the posterior abdominal wall.
Posterior Wall of the Femoral Sheath. — There are still
some additional facts relating to the posterior wall of the
External
cutaneous nerve*
Iliopsoas
Poupart's ligament
Anterior crural nervex
Fig. 73. — Dissection to show the Femoral Sheath and the other Structures
which pass between Poupart's Ligament and the Innominate Bone.
femoral sheath which require to be mentioned. It is formed,
as stated above, by the fascia iliaca ; but as this enters the
thigh it becomes continuous with the pubic layer of the fascia
lata, and further, it is firmly fixed in position by certain con-
nections which it establishes in the thigh. Thus beyond
the femoral sheath it is prolonged in an outward direction
over the ilio-psoas muscle, whilst from its posterior aspect a
lamina is given off which passes behind that muscle and joins
the capsule of the hip-joint.
206 THE LOWER LIMB
Dissection. — The femoral sheath should be opened, in order that the
arrangement of parts inside may be displayed. Make three vertical and
parallel incisions through the anterior wall — one over the femoral artery
which occupies the outer part of the sheath, another over the femoral vein,
and the third about half an inch internal to the second. The first two
should begin at the level of Poupart's ligament, and should extend down-
wards for an inch and a half. The most internal of the three incisions
should commence at the same point, but should only be carried downwards
for half an inch or less.
Interior of the Femoral Sheath. — A little dissection will
show that the sheath is subdivided by two vertical partitions
into three compartments. The femoral artery and crural
branch of the genito-crural nerve occupy the outermost com-
partment ; the femoral vein fills up the middle compartment ;
whilst in the innermost compartment is lodged a little loose
areolar tissue, a small lymphatic gland, and some lymphatic
vessels. This last compartment, from its relation to femoral
hernia, has the special name of crural canal applied to it.
Crural Canal. — The boundaries and extent of this canal
must be very thoroughly studied. The best wray to do this is
to introduce the little finger into it and gently push it upwards.
Its length is not nearly so great as that of the other two
compartments. Indeed it is not more than half an inch long.
Inferiorly it is closed, and it rapidly diminishes in width from
above downwards. Its superior aperture lies on the outer
side of the base of Gimbernat's ligament, and is called the
crural ring. It is closed by the closely applied extra-peritoneal
fatty tissue of the abdominal wall. The parts which imme-
diately surround this opening can be readily detected with
the finger : externally the fe?noral vein, internally the sharp
crescentic base of Gbnbernaf s ligament, anteriorly Pouparfs
ligament, and posteriorly the pubic bone covered by the pectineus
muscle. The portion of the extra-peritoneal fatty tissue which
closes the ring is called the seption crurale. On the
abdominal surface of the septum crurale is the peritoneal
lining of the abdominal cavity, and when examined from
above both are seen to be slightly depressed into the open-
ing so as to produce the appearance of a dimple.
Femoral Hernia. — Femoral hernia is the name applied to a pathological
condition which consists in the protrusion of a viscus or part of a viscus
from the abdominal cavity into the region of the thigh. In its descent it
passes behind Poupart's ligament within the crural canal or innermost
compartment of the femoral sheath. The arrangement of the parts which
occupy the interval between the innominate bone and Poupart's ligament
has been carefully considered, and the dissector should therefore be in a
FRONT OF THE THIGH 207
position to understand how the occurrence of such a protrusion is rendered
possible. To the inner side of the femoral sheath the interval is closed
by Gimbernat's ligament, which, by its strength and firm connections,
constitutes an impassable barrier in this locality. To the outer side of the
femoral sheath a hernial protrusion is equally impossible. Here the fascia
transversalis on the anterior wall of the abdomen becomes continuous with
the fascia iliaca on the posterior wall of the abdomen, and along the line
of union both are firmly attached to Poupart's ligament.
It is in the region of the femoral sheath, then, that femoral hernia takes
place. Its three compartments open above into the abdominal cavity, but
there is an essential difference between these three openings. The outer
two, which hold the artery and the vein, are completely filled up by their
contents. The crural canal, or innermost compartment, is not ; it is much
wider than is necessary for the passage of the fine lymphatic vessels which
traverse it. P\irther, its widest part is the upper opening or antral ring.
It has been noted that this is wide enough to admit the point of the little
finger. Here then is a weak point in the parietes of the abdomen, and a
source of weakness which is greater in the female than in the male, seeing
that in the former the distance between the iliac and pubic spines is
proportionally greater, and in consequence the crural ring wider. Femoral
hernia, therefore, is more common in the female.
When attempts are made to reduce a femoral hernia, it is absolutely
necessary that the course which the protrusion has taken should be kept
constantly before the mind of the operator. In the first instance it descends
for a short distance in a perpendicular direction. It then turns forward
and bulges through the saphenous opening. Should it still continue to
enlarge, it bends upwards over Poupart's ligament, and pushes its way
outwards towards the anterior superior spine of the ilium. The protrusion
is thus bent upon itself : if reduction is to be carried out successfully it
must be made to retrace its steps. In other words, it must be drawn
downwards, and then pushed gently backwards and upwards. The position
of the limb during this procedure must be attended to. When the thigh
is fully extended and rotated outwards, all the fascial structures in the
neighbourhood of the crural canal are rendered tight and tense. When
the limb is flexed at the hip-joint and rotated inwards, on the other hand,
the superior cornu of the falciform edge of the saphenous opening, and
even Gimbernat's ligament, are relaxed. This, then, is the position in
which the limb should be placed during the reduction of the hernia.
As the hernia descends it carries before it the various layers which it
meets in the form of coverings. First it pushes before it the peritoneum,
and this forms the hernial sac. The other coverings from within outwards
are — (1) the septum crurale ; (2) the wall of the femoral sheath (if it does
not burst through one of the apertures in this) ; (3) the cribriform fascia ;
(4) and lastly, the superficial fascia and skin.
The crural canal, as we have noted, is surrounded by very unyielding
structures. Stricture in cases of femoral hernia is therefore a matter of
very common occurrence. The sharp base of Gimbernat's ligament and
the superior cornu of the falciform edge of the saphenous opening are
especially apt to bring about this condition.
Abnormal Obturator Artery. — But the account of the surgical anatomy
of femoral hernia would not be complete if we omitted to mention the
relation which the obturator artery frequently bears to the crural ring. In
two out of every five subjects the obturator artery, on one or on both sides,
takes origin from the deep epigastric. In these cases it passes backwards
to gain the obturator canal in the upper part of the thyroid foramen.
According to the point at which it arises from the epigastric trunk, it
2o8 THE LOWER LIMB
presents different relations to the femoral ring. In the majority of cases
it proceeds backwards in close contact with the external iliac vein and on
the outer side of the femoral ring. In this position it is in no danger of
being wounded in operations undertaken for the relief of a strictured
femoral hernia. In about thirty-seven per cent, however, of the cases in
which it exists, the artery is placed less favourably. In these, it either
proceeds backwards across the septum crurale which closes the opening
into the crural canal, or it arches over it and turns backwards on the
inner side of the ring upon the deep aspect of the base of Gimbernat's
ligament. In the latter situation it is in a position of great danger, seeing
that it is the base of Gimbernat's ligament against which the surgeon's
knife is generally directed for the relief of strictured femoral hernia.
Dissection. — Scarpa's triangle may now be dissected. To bring its
boundaries into view the deep fascia must be removed from the anterior
aspect of the upper third of the thigh. In the lower two-thirds of the
thigh, the fascia lata should be left undisturbed, so as to maintain as far as
possible the natural position of parts.
Scarpa's Triangle. — This is the name which is given to the
triangular hollow which lies in the upper part of the thigh
below Poupart's ligament.
The outer boundary is formed by the sartorius muscle as it
runs downwards and inwards across the thigh from the
anterior superior spine of the ilium ; and the inner boundary
is constituted by the prominent internal margin of the adductor
longus muscle. These muscles meet below to form the apex of
the triangle. Pouparfs ligament forms the base of the triangle.
The contents of the space must now be displayed by remov-
ing the fatty areolar tissue which surrounds them. The
femoral vessels should first be cleaned. Remove the remains
of the femoral sheath and define the various branches which
proceed from the vessels in so far as they are seen within the
limits of the triangular space. Be careful not to injure the
small twig which springs from the anterior crural nerve, and
passes inwards behind the vessels a short distance below
Poupart's ligament, to supply the pectineus muscle. In this
part of its course the femoral artery gives off — (i) the three
superficial inguinal vessels, which have already been observed
ramifying in the superficial fascia of the groin ; (2) the deep
external pudic, which runs inwards over the pectineus ; (3)
the large profunda femoris.
The profunda femoris comes off from the outer side of the
femoral artery about one and a half inches below Poupart's
ligament. It inclines downwards and inwards behind the
femoral trunk, and soon leaves the space by passing under
cover of the adductor longus. The external and internal
FRONT OF THE THIGH
209
circumflex arteries will be seen to arise from the profunda
femoris within Scarpa's triangle.
The external circutnflex should be traced outwards as it
passes amongst the branches of the anterior crural nerve, to
disappear under cover of the outer boundary of the space.
The internal circumflex is lost to view shortly after its origin
by sinking backwards through the floor of the space between
External cutaneous nerve
Poupart's ligament
Superficial circumflex iliac artery
Anterior crural nerve
Superficial inguinal arteries
Profunda femoris
External circumflex
Middle cutaneous
nerve
Crural branch of genito-
crural nerve
Deep external pudic
f ^-Adductor brevis
Femoral vein
^Femoral artery
Fig. 74. — Dissection of Scarpa's Triangle.
the pectineus and psoas muscles. The veins corresponding
to these arteries must be cleaned at the same time.
Certain nerves are also to be found in this space, viz. — (1)
the crural branch of the genito-crural \ (2) the external cutaneous ;
and (3) the anterior crural. The crural branch of the genito-
crural descends in the outermost compartment of the femoral
sheath on the outer side of the femoral artery. It pierces
the external wall of the sheath and the fascia lata a short
distance below Poupart's ligament, and has already been
vol. 1 — 14
210 THE LOWER LIMB
traced to its distribution (p. 196). The external cutaneous
nerve passes into the thigh behind Poupart's ligament, close
to the anterior superior spine of the ilium. It soon leaves
the triangle by crossing the sartorius and piercing the fascia
lata. It has already been traced in its ramifications in the
superficial fascia on the outer aspect of the thigh. The
anterior crural nerve will be detected lying deeply in the
interval between the psoas and iliacus muscles, about a
quarter of an inch to the outer side of the femoral artery.
Insinuate the handle of a knife under the main trunk, so as to
raise it above the level of the muscles between which it lies,
and render it tense, and then follow the numerous branches
into which it breaks up as far as the limits of the space will
allow. The minute twig to the pectineus muscle must be
looked for. It passes inwards behind the femoral vessels.
Theyftwof Scarpa's triangle slopes backwards both from
the inner and the outer boundary of the space. To the
inner side of the femoral artery it is formed by the adductor
longus and the pectineus ; in some cases a small portion of the
adductor brevis may be seen in a narrow interval between
these two muscles. To the outer side of the artery are the
psoas and iliacus. The adductor longus is placed in an
oblique plane, the inner border being nearer the surface than
the outer border ■ and thus it is that this muscle not only
forms the inner boundary of the triangle, but also takes part
in the formation of the floor. These muscles should be
cleaned in so far as they stand in relation to Scarpa's triangle.
When a transverse section is made through the frozen thigh in the
region of Scarpa's triangle, the space appears more in the shape of a deep
intermuscular furrow, bounded on the inner side by the adductor longus
and pectineus, and on the outer side by the sartorius and rectus femoris,
whilst behind it is separated from the bone by the ilio-psoas. The femoral
vessels and the anterior crural nerve pass downwards in this groove — the
profunda femoris being placed very deeply, whilst the femoral artery lies
nearer to the surface.
Femoral Artery (arteria femoralis). — The femoral artery,
the great arterial trunk of the lower limb, is the direct con-
tinuation of the external iliac. It begins at Poupart's liga-
ment, behind which it enters the thigh, and it extends down-
wards to the opening in the adductor magnus, through
which it gains the popliteal space and becomes^ the popliteal
artery. This opening is situated on the inner aspect of the
lower third of the thigh, and the course which the vessel
FRONT OF THE THIGH 211
pursues may be marked on the surface, when the thigh is
slightly abducted and rotated outwards, by an oblique line
drawn from a point midway between the anterior superior
iliac spine and the symphysis pubis to the internal condyle of
the femur.
The relations which the artery bears to the femur are im-
portant. As it enters Scarpa's triangle it passes from the
brim of the pelvis and comes to lie in front of the inner part
of the head of the femur, from which it is separated by the
psoas muscle. Although its relation to the bone is tolerably
intimate, this situation should not be chosen for applying
compression. On account of the mobility of the head of the
bone there is a liability for the vessel to slip from under the
fingers. It is much safer to compress it against the brim of
the pelvis. Below the head of the femur, during the re-
mainder of its course through Scarpa's triangle, the artery is
not in direct relation to the bone. It crosses in front of the
angular interval between the neck and shaft of the femur.
Towards the apex of the space, however, it comes into re-
lation with the inner side of the shaft of the femur, and this
position it holds to its termination.
In the present condition of the dissection it is only that
part of the femoral artery which traverses Scarpa's triangle
which comes under the notice of the dissector. The length of
this part varies with the development of the sartorius muscle,
and the degree of obliquity with which this crosses the front
of the thigh. It measures from three to four inches in
length, and is comparatively superficial throughout its entire
course. At the apex of the triangle the femoral artery
disappears under cover of the sartorius and takes up a
deeper position in the limb.
In Scarpa's triangle the femoral artery is enveloped in its
upper part by the femoral sheath, and is separated from the
surface by the skin, superficial fascia, and deep fascia, whilst
below it is crossed by the internal cutaneous nerve, which
runs along the inner border of the sartorius muscle. Behind
the vessel is the psoas, and then the pectineus muscle. It
rests directly upon the psoas — the femoral sheath and the
nerve to the pectineus, as it crosses inwards, alone interven-
ing ; but it is separated from the pectineus by an interval
occupied by fatty areolar tissue, and here also the profunda
artery crosses behind it, and the femoral vein is seen to have
212 THE LOWER LIMB
a position posterior to it. Upon the outer side of the femoral
artery is the anterior crural nerve — but not in apposition
with it, as a small portion of the psoas intervenes. The
fe?noral vein changes its position with reference to the artery,
as it is traced from above downwards. In the upper part of
the space it lies on the same plane and to the inner side of
the artery, but lower down it becomes more deeply placed
and gradually assumes a position posterior to the artery.
The branches which the femoral artery gives off in Scarpa's
triangle have already been enumerated (p. 208). One of
these, viz., the deep external pudic, may now be traced to its
destination.
Deep External Pudic Artery. — This is a small twig which
arises from the inner side of the femoral, a short distance
below Poupart's ligament. It extends inwards upon the
pectineus and adductor longus muscles, and, piercing the
fascia lata, ends, according to the sex, in the integument of
the scrotum or of the labium pudendi.
Dissection. — The fascia lata may now be removed from the lower two-
thirds of the thigh. This can best be effected by dividing it along the
middle line of the limb, and throwing it outwards and inwards. Preserve
undisturbed the thickened band of fascia (ilio-tibial band) on the outer side
of the thigh.
In cleaning the sartorius muscle several of the nerves of the thigh will
be found intimately related to it, and must be carefully dissected. The
middle cutaneous nerve frequently pierces its upper border, and then
proceeds downwards in front of it ; the anterior branch of the internal
cutaneous crosses it at a lower level, whilst the posterior branch of the
same nerve is carried downwards along its posterior border. Near the
knee it lies over the long saphenous nerve, which ultimately comes to
the surface between it and the gracilis. A short distance above this the
sartorius is pierced by the patellar branch of the long saphenous. Lastly,
about the middle of the thigh, there is formed under cover of the sartorius
an interlacement of fine nerve twigs derived from the posterior branch of
the internal cutaneous, the long saphenous, and the obturator. On raising
the sartorius from subjacent parts this must be looked for.
The different portions of the quadriceps extensor muscle must also be
cleaned, and the branches which the anterior crural nerve gives to them, as
well as the descending branch of the external circumflex artery, traced to
their terminations.
Sartorius. — The sartorius is a long slender muscle, which
arises from the anterior superior spine of the ilium and the
upper part of the notch on the anterior border of the bone
immediately below. It crosses the front of the upper third
of the thigh obliquely, and gaining the inner side of the limb,
it takes a nearly vertical course downwards to a point beyond
FRONT OF TH^ THIGH
213
the inner prominence of the knee. "Here it turns forwards,
and ends in a thin, expanded aponeurotic tendon, which is
inserted into the inner surface of the shaft of the tibia, behind
the anterior tubercle (Fig. 68, p. 187). By its lower border this
tendon is connected with the fascia of the leg, whilst by its
upper border it is joined to the capsule of the knee-joint.
In its upper oblique part the sartorius muscle forms the
Internal saphenous vein
Aponeurosis covering
in the canal
Long saphenous
nerve
Femoral vessels
Aponeurotic ex-
pansion covering
canal (cut edges)
Tendon of
adductor magnus
Sartorius
Internal saphenous
vein
Fig. 75. — Dissection of Hunter's Canal in the left lower limb. A portion
of the Sartorius has been removed.
outer boundary of Scarpa's triangle, and lies in front of the
iliacus, the rectus femoris, and the adductor longus muscles.
Below this, it is placed over the femoral vessels as far as the
opening in the adductor magnus. At its insertion its ex-
panded tendon lies in front of, and covers, the tendons of
insertion of the gracilis and semitendinosus, but is separated
from them by a bursa. The sartorius is supplied by the
anterior division of the anterior crural nerve.
Hunter's Canal (canalis adductorius Hunteri). — When the
2 14
THE LOWER LIMB
femoral artery leaves Scarpa's triangle it is continued down-
wards on the inner side of the thigh, in a deep furrow, which
is bounded in front by the vastus internus muscle, and behind
by the adductor muscles. If this furrow be traced upwards,
it will be seen to run into the deeper, wider, and more
apparent hollow, which has been described as Scarpa's space.
Further, this intermuscular recess is converted into a canal,
triangular on transverse section, by a strong fibrous membrane
which stretches across it, and upon the surface of which the
sartorius muscle is placed (Fig. 76). The tunnel thus formed
is called " Hunter's Canal." When the fibrous expansion
which closes in the canal is traced upwards, it is seen to
Vastus internus
Crureus
Sartorius
Femoral vessels and
long saphenous nerve
in Hunter's canal
Adductor
Vastus externus
Fig. 76. — Transverse Section through Hunter's Canal.
become thin and ill-defined as it approaches Scarpa's triangle ;
when traced in the opposite direction, however, it becomes
dense and strong, and opposite the opening in the adductor
magnus it presents a thick, sharply defined margin. It
stretches from the tendons of the adductor longus and the
adductor magnus behind to the vastus internus in front. In
its lower part the posterior wall of the canal, where it is
formed by the adductor magnus, presents a deficiency or
aperture which leads backwards into the popliteal space.
The appearance and construction of this aperture will be
studied at a later stage. It is called the opening i?i the
adductor magnus.
The femoral vessels and the long saphenous nerve traverse
Hunter's canal. In this part of its course the artery gives
FRONT OF THE THIGH
2 I
off some muscular twigs and the anastomotica magna branch.
The femoral vessels leave the canal at its lower end by inclin-
ing backwards through the opening in the adductor magnus
and entering the popliteal space. The long saphenous nerve,
accompanied by the superficial branch of the anastomotica
magna artery, escape from the canal by passing under cover of
the lower thickened margin of the fibrous expansion which
closes it in. They can be seen in the present stage of the
dissection in this situation.
External cutaneous nerve
Femur
Vastus externus
Profunda vessels
G reat sciatic nerve
Biceps
Rectus femoris
Middle cutaneous
nerve
Sartorius
Femoral vessels in
Hunter's canal
j2?c((8)4— Internal saphenous
[■9/ J Adductor longus
Semitendinosus
Gracilis
\ Adductor magnus
Semimembranosus
Fig. 77. — Transverse Section through the Middle of the Thigh.
Relationship of the parts in Hunter's Canal is seen.
The
Dissection. — The fibrous expansion which is stretched across Hunter's
canal under cover of the sartorius muscle should now be divided, in order
that the arrangement of the parts within the canal may be studied.
Lower Portion of the Femoral Artery. — The entire length
of the femoral artery is now exposed. Below the apex of
Scarpa's triangle it enters Hunter's canal, and is separated
from the inner surface of the thigh by the fibrous expansion
which closes the canal, the sartorius muscle, the fascia lata,
and the integument. The long saphenous nerve at first lies
to the outer side of this portion of the vessel and then in
front of it. From above downwards the artery rests upon the
pectineus, the adductor brevis, the adductor longus, and the
adductor magnus. In its upper part, however, it is separated
1 — 14 a
216 THE LOWER LIMB
from these muscles by the femoral vein, which lies behind it ;
lower down, the vein, which inclines outwards, comes to lie
on its outer side. The relation of parts in the lower portion
of Hunter's canal is seen in Figs. 76 and 77. The two
vessels are placed side by side, whilst the long saphenous
nerve is in front of the artery.
From the femoral artery, as it traverses Hunter's canal,
proceed muscular twigs and the anastomotic branch.
The muscular branches are irregular in number and in
their mode of origin. They supply the vastus internus, the
adductor longus, and the sartorius.
Anastomotic Artery (arteria genu suprema). — This branch
springs from the femoral trunk a short distance above the
point where it enters the popliteal space by passing through
the opening in the adductor magnus. The anastomotic artery
almost immediately divides into a superficial and a deep
branch : very frequently, indeed, these branches take separate
origin from the femoral artery.
The superficial branch accompanies the long saphenous
nerve, and leaves Hunter's canal by passing under cover of
the lower border of the fibrous expansion which is stretched
over the canal. On the inner side of the knee it appears
between the gracilis and sartorius, and it ends in branches
to the integument on the inner aspect of the upper part of
the leg.
The deep branch enters the substance of the vastus internus
and proceeds downwards in front of the tendon of the
adductor magnus. It gives some twigs to the vastus internus
and others which spread out over the upper and inner aspect
of the knee-joint, and anastomose with branches of the
internal articular arteries. One well-marked branch runs out-
wards above the patella to anastomose with the superior
external articular artery.
Femoral Vein (vena femoralis). — This is the direct con-
tinuation upwards of the popliteal vein. It begins at the open-
ing in the adductor magnus, through which it enters Hunter's
canal, whilst above, it passes behind Poupart's ligament and
becomes continuous with the external iliac vein. It accom-
panies the femoral artery, but the relations of the two vessels
to each other differ at different stages of their course. In
the lower part of Hunter's canal the vein lies on the outer
side of the artery, but it inclines inwards as it ascends, and
FRONT OF THE THIGH 217
in the upper part of the thigh it lies on its inner side and on
the same plane. The crossing from one side to the other
takes place behind the artery and is very gradual, so that for
a considerable distance the femoral vein lies directly behind
the femoral artery. For a distance of two inches below
Poupart's ligament it is enclosed within the femoral sheath,
of which it occupies the middle compartment.
In its journey up the thigh the femoral vein receives
tributaries which for the most part correspond with the
branches of the femoral artery. At the saphenous opening it
is joined by the internal saphenous vein. The dissector
should slit the femoral vein open with the scissors. Several
valves will then be seen. One is almost invariably found
immediately above the entrance of the vein which corresponds
to the profunda artery.
Anterior Crural Nerve (nervus femoralis). — The anterior
crural nerve is a large nerve which arises within the abdomen
from the lumbar plexus. It enters the thigh by passing
downwards in the interval between the psoas and iliacus
muscles and behind Poupart's ligament and the fascia iliaca.
In the upper part of the thigh it lies to the outer side of the
femoral artery, and is separated from it by a small portion of
the psoas muscle and the femoral sheath. A short distance
below Poupart's ligament it divides into an anterior and a
posterior portion, which at once resolve themselves into a
large number of cutaneous and muscular branches. The
following is a list of these : —
f ,T , , , f To the pectineus.
Muscular branches, r , .
. . • ,. . • ' ,, sartonus.
Anterior division, ■{ > *,,-• V,,
' ^ , , , I Middle cutaneous
Cutaneous branches
Posterior division,
\ Internal cutaneous.
To the rectus femoris.
,, vastus internus.
Muscular branches, ., vastus externus.
crureus.
subcrureus.
Cutaneous branch, Long saphenous.
Articular branches.
With the exception of the long saphenous, which is distributed
upon the inner side of the leg and foot, the distribution of the
cutaneous branches of the anterior crural has been already
examined (p. 197).
The nerve to the pectineus arises a short distance below
Poupart's ligament and turns inwards behind the femoral
218 THE LOWER LIMB
vessels to reach its destination. The branches to the sartorius
are two or three in number. As a rule they take origin by a
common trunk with the middle cutaneous nerve.
The middle cutaneous nerve sometimes pierces the upper
border of the sartorius. It divides into two branches which
perforate the fascia lata about three or four inches below
Poupart's ligament.
The internal cutaneous nerve inclines downwards and
inwards, and crosses in front of the femoral artery. It
divides into an anterior and a posterior portion, which become
superficial at different levels on the inner side of the limb.
From the trunk of the nerve a few cutaneous twigs are given
to the skin over the upper and inner part of the thigh. The
anterior branch crosses the sartorius muscle and makes its
appearance through the fascia lata in the lower part of the
thigh, a short distance in front of the saphenous vein. The
posterior branch runs downwards along the posterior border of
the sartorius, and pierces the deep fascia on the inner side of
the knee behind that muscle and the long saphenous nerve.
A short distance below the middle of the thigh the posterior branch of
the internal cutaneous nerve forms, with filaments from the obturator nerve
and the long saphenous nerve, a plexiform interlacement, the sartorial
plexus, which is placed under the sartorius muscle, as it lies over Hunter's
canal. The twig from the obturator nerve appears at the inner border of
the adductor longus.
The long saphenous nerve is the largest branch of the
anterior crural. It springs from the posterior division of that
nerve and extends downwards on the outer side of the
femoral artery. Entering Hunter's canal with the femoral
vessels it comes to lie in front of the artery. At the lower
end of the canal it emerges, by passing under cover of the
thickened border of the fibrous expansion which stretches
between the vastus internus and the adductor muscles, and,
accompanied by the superficial branch of the anastomotic
artery, it escapes from under cover of the sartorius and
pierces the deep fascia at the inner side of the knee. It
gives off the patellar branch after it quits Hunter's canal.
This branch pierces the sartorius and appears on the surface
of the fascia lata on the inner side of the knee.
Several large branches of the posterior part of the anterior
crural nerve enter the four factors which compose the great
quadriceps extensor muscle of the thigh. From certain of
FRONT OF THE THIGH 219
these, articular filaments are given to the hip and knee-
joints.
The branch to the rectus femoris sinks into the deep surface
of this muscle. It supplies an articular twig to the hip-joint.
The large branch to the vastus internus accompanies the long
saphenous nerve, and enters with it the upper part of
Hunter's canal. It can readily be distinguished from its
sinking into the inner aspect of the vastus internus about the
middle of the thigh. In the substance of this muscle it
extends downwards, and near the knee joins the deep branch
of the anastomotic artery. It gives an articular nerve to the
synovial membrane of the knee-joint. The fierve to the vastus
externus is associated with the descending branch of the
external circumflex artery. Very frequently it gives an
articular twig to the knee-joint. The nerves to the crureus
are two or three in number, and they sink into its anterior
surface. The innermost of these is a long slender nerve,
which can be traced downwards under the anterior border
of the vastus internus to the subcrureus. Its terminal twigs
are given to the synovial membrane of the knee-joint.
One filament then from the anterior crural goes to the hip-
joint; two, and frequently three, filaments go to the knee-joint.
Ilio-tibial Band of Fascia Lata. — The thick band of fascia
lata on the outer side of the thigh which receives this name
should now be examined, and its connections ascertained.
It has been preserved for this purpose. Inferiorly it is
attached to the outer tuberosity of the tibia and to the head
of the fibula. On tracing it upwards on the outer surface of
the vastus externus it will be observed to split at the junction
of the middle and upper thirds of the thigh into two lamellae
— a superficial and a deep. The tensor fasciae femoris is
enclosed between these layers, and when they are disengaged
from its surfaces the muscle will be seen to be inserted into
the fascia at the angle of splitting. The superficial lamina of
the ilio-tibial band is attached above to the crest of the ilium,
and is continuous posteriorly with the gluteal aponeurosis
where this covers the gluteus medius. The deep lamina can
be followed upwards on the outer surface of the rectus femoris
to the capsule of the hip-joint, with the upper and outer part
of which it blends. It is also connected with the reflected
tendon of the rectus femoris. This layer is perforated by
the ascending twigs of the external circumflex artery.
220 THE LOWER LIMB
Tensor Fasciae Femoris (musculus tensor fasciae latae). —
This is a small muscle which is placed on the outer and
anterior aspect of the upper third of the thigh. It lies
between the two lamellae of the ilio-tibial band of fascia, in
the interval between the sartorius muscle in front and the
gluteus medius muscle behind. On turning the muscle out-
wards so as to display its deep surface, a little dissection will
bring into view its nerve of supply which comes from the
superior gluteal nerve. This nerve, however, has in all prob-
ability been already exposed in the dissection of the gluteal
region. A few arterial twigs from the external circumflex
also sink into its deep surface.
The tensor fascia femoris arises from a small portion of the
anterior part of the crest of the ilium ; from the upper part
of the notch below the anterior superior spine of the ilium ;
and by some fibres from the aponeurosis covering the gluteus
medius. It extends downwards with a slight inclination
backwards, and is inserted into the ilio-tibial band of fascia
lata at its angle of splitting.
External Circumflex Artery (arteria circumflexa femoris
radialis). — This is the largest branch which proceeds from
the profunda femoris. It arises near the origin of the latter
from the femoral artery, and runs outwards between the
divisions of the anterior crural nerve and under cover of the
sartorius and rectus femoris muscles. It ends by dividing
into ascending, transverse, and descending branches.
The ascending branch reaches the dorsum ilii by passing
under cover of the tensor fasciae femoris. Its terminal twigs
anastomose with the gluteal artery. The transverse branch is
of small size and passes to the deep surface of the vastus
externus. It reaches the back of the thigh, and inosculates
with the internal circumflex and the first perforating arteries.
The descending branch gives twigs to the crureus and rectus
femoris and one long branch, which may be traced down-
wards amid the fibres of the vastus externus to the knee,
where it anastomoses with the superior external articular
artery.
Intermuscular Septa. — Divide the ilio-tibial band of fascia
lata below the point at which it splits to enclose the tensor
fasciae femoris. This is done so as to obtain a better view of
the vastus externus, and in order to demonstrate satisfactorily
the external intermuscular septum. Take hold of the lower
FRONT OF THE THIGH
22 I
portion of the ilio-tibial band, and draw it forcibly outwards ;
at the same time push inwards the vastus externus muscle,
and a strong fibrous septum will be seen passing inwards
from the fascia; lata towards the linea aspera. This is the
external intermuscular septum of the thigh, a partition inter-
posed between the vastus externus and the short head of the
biceps. Follow it upwards and downwards with the finger.
The fibres of the vastus externus are seen arising from it, but
Rectus femoris (straight head of origin)
.Rectus femoris (reflected head of origin)
Attachment of ilio-femoral band Adductor longus (origin)
Pyramidalis abdominis (origin)
Rectus abdominis (origin)
emimembran- g- ^ V*-1 M S * W \ Gracilis (origin)
osus (origin)
Quad rat us |^ \^K/,^': ~^N- y^ ^ f/£j/OJ Adductor brevis (origin)
moris (origin)
Biceps and
:mitendinosus
(origin)
Fig. 78. — Muscle- Attachments to the Outer Surface of the Pubis and Ischium.
little difficulty will be experienced in making out its attach-
ment to the linea aspera and external supracondyloid ridge
of the femur. It extends in an upward direction as far as
the insertion of the gluteus maximus, whilst below, it reaches
the external tuberosity of the lower end of the femur. Im-
mediately above the external condyle of the femur it is
pierced by the superior external articular vessels and nerve.
The internal intermuscular septum is interposed between the
adductors and the vastus intemus, and should also be
examined. It is thin in comparison with the external septum.
222
THE LOWER LIMB
Obturator internus
Pyriformi:
Quadriceps Extensor Cruris (musculus quadriceps femoris).
— This muscle is composed of four portions. The rectus
femoris, which is placed on the front of the thigh, is quite
distinct from the others, except at its insertion ; the vastus
externus, the crureus, and the vastus internus clothe the shaft
of the femur on its outer, anterior, and inner aspects, and are
more or less blended with each other.
The Rectus Femoris arises by two tendinous heads of
origin, which may be exposed by dissecting deeply in the
interval between the
iliacus and tensor
fasciae femoris. The
anterior or straight head
springs from the an-
terior inferior spine of
the ilium (Fig. 61, p.
163) ; the posterior or
reflected head arises from
a marked impression
on the outer surface
of the ilium, imme-
diately above the upper part
of the rim of the acetabulum
(Fig. 61, p. 163), and is con-
nected both with the capsule of
the hip-joint and the deep
lamina of the ilio -tibial band
of fascia lata. The two heads
of origin of the rectus femoris
join at a right angle immediately
beyond the margin of the aceta-
bulum, and form a strong flattened tendon, which gives
place to a fusiform, fleshy belly. The tendon of origin
spreads out on the anterior surface of the muscle in its upper
part in the form of an aponeurosis. About three inches
above the knee-joint the rectus femoris ends in a strong
tendon of insertion, which is prolonged for some distance
upwards on its deep surface in the form of an aponeurosis.
As it nears the patella, this tendon is joined by the other
tendons of the quadriceps, and through the medium of a com-
mon tendon finds insertion into the upper border of that bone.
The rectus femoris is supplied by the anterior crural nerve.
Fig. 79. — Front Aspect of Upper
Portion of Femur with Attachments
of Muscles mapped out.
FRONT OF THE THIGH 223
The Vastus Externus (musculus vastus lateralis) forms the
prominent muscular mass on the outer side of the thigh. Its
surface is covered by a glistening aponeurosis. The descend-
ing branch of the external circumflex artery constitutes the
best guide to its anterior border, and when this margin is
raised it will be seen that the muscle lies upon, and is
partially blended with, the crureus.
The vastus externus arises — (1) from the upper part of
the anterior intertrochanteric line; (2) from the front of the
great trochanter, anterior to the insertion of the gluteus
minimus; (3) from the root of the great trochanter below
the insertion of the gluteus medius ; (4) from the outer part
of the gluteal ridge in front of the insertion of the gluteus
maximus ; (5) from the upper part of the linea aspera ; and
(6) from the external intermuscular septum. The fleshy
fibres are for the most part directed downwards and forwards.
By means of the common tendon of insertion the muscle
gains insertion into the patella, and at the same time gives an
expansion to the capsule of the knee-joint. It is supplied by
the anterior crural tierve.
The Vastus Internus (musculus vastus medialis) is
intimately connected with the crureus, but not to such an
extent as might be inferred from a superficial inspection.
In its upper part the anterior border, which is fleshy, is either
contiguous or blended with the crureus ; below, the anterior
border is tendinous and overlaps the crureus, but it is not
as a rule fused with it.
"A line drawn from the middle of the anterior intertrochanteric line
downwards and slightly outwards to the middle of the upper border of the
patella will define accurately the thick anterior border of the vastus
internus." — (Williams.) Divide the rectus femoris about its middle, and
pull the lower part forcibly downwards. The narrow interval between the
tendons of the crureus and vastus internus will then become apparent, and
may be followed upwards. A still further guide is the long, slender nerve
of supply to the subcrureus, which runs along the inner edge of the crureus.
When the anterior border of the vastus internus is raised from the crureus,
the inner surface of the shaft of the femur will be seen to be perfectly bare.
No muscular fibres arise from this bony surface. The fleshy mass of the
vastus internus may now, with advantage, be divided transversely about
two inches above the patella. The muscle can then be thrown inwards,
and its origin studied.
The vastus internus arises — (1) from the lower part of the
anterior intertrochanteric line of the femur; (2) from the line
leading from this, below the small trochanter, to the linea
aspera; (3) from the inner lip of the linea aspera ; (4) from
222
THE LOWER LIMB
Obturator internus
Pyrifor
Quadriceps Extensor Cruris (musculus quadriceps femoris).
— This muscle is composed of four portions. The rectus
femoris, which is placed on the front of the thigh, is quite
distinct from the others, except at its insertion ; the vastus
externus, the crureus, and the vastus internus clothe the shaft
of the femur on its outer, anterior, and inner aspects, and are
more or less blended with each other.
The Rectus Femoris arises by two tendinous heads of
origin, which may be exposed by dissecting deeply in the
interval between the
iliacus and tensor
fasciae femoris. The
anterior or straight head
springs from the an-
terior inferior spine of
the ilium (Fig. 61, p.
163) ; the posterior or
reflected head arises from
a marked impression
on the outer surface
of the ilium, imme-
diately above the upper part
of the rim of the acetabulum
(Fig. 61, p. 163), and is con-
nected both with the capsule of
the hip-joint and the deep
lamina of the ilio -tibial band
of fascia lata. The two heads
of origin of the rectus femoris
join at a right angle immediately
beyond the margin of the aceta-
bulum, and form a strong flattened tendon, which gives
place to a fusiform, fleshy belly. The tendon of origin
spreads out on the anterior surface of the muscle in its upper
part in the form of an aponeurosis. About three inches
above the knee-joint the rectus femoris ends in a strong
tendon of insertion, which is prolonged for some distance
upwards on its deep surface in the form of an aponeurosis.
As it nears the patella, this tendon is joined by the other
tendons of the quadriceps, and through the medium of a com-
mon tendon finds insertion into the upper border of that bone.
The rectus femoris is supplied by the anterior crural nerve.
Fig. 79. — Front Aspect of Upper
Portion of Femur with Attachments
of Muscles mapped out.
FRONT OF THE THIGH 223
The Vastus Externus (musculus vastus lateralis) forms the
prominent muscular mass on the outer side of the thigh. Its
surface is covered by a glistening aponeurosis. The descend-
ing branch of the external circumflex artery constitutes the
best guide to its anterior border, and when this margin is
raised it will be seen that the muscle lies upon, and is
partially blended with, the crureus.
The vastus externus arises — (1) from the upper part of
the anterior intertrochanteric line; (2) from the front of the
great trochanter, anterior to the insertion of the gluteus
minimus ; (3) from the root of the great trochanter below
the insertion of the gluteus medius ; (4) from the outer part
of the gluteal ridge in front of the insertion of the gluteus
maximus ; (5) from the upper part of the linea aspera ; and
(6) from the external intermuscular septum. The fleshy
fibres are for the most part directed downwards and forwards.
By means of the common tendon of insertion the muscle
gains insertion into the patella, and at the same time gives an
expansion to the capsule of the knee-joint. It is supplied by
the anterior crural nerve.
The Vastus Internus (musculus vastus medialis) is
intimately connected with the crureus, but not to such an
extent as might be inferred from a superficial inspection.
In its upper part the anterior border, which is fleshy, is either
contiguous or blended with the crureus ; below, the anterior
border is tendinous and overlaps the crureus, but it is not
as a rule fused with it.
"A line drawn from the middle of the anterior intertrochanteric line
downwards and slightly outwards to the middle of the upper border of the
patella will define accurately the thick anterior border of the vastus
internus." — (Williams.) Divide the rectus femoris about its middle, and
pull the lower part forcibly downwards. The narrow interval between the
tendons of the crureus and vastus internus will then become apparent, and
may be followed upwards. A still further guide is the long, slender nerve
of supply to the subcrureus, which runs along the inner edge of the crureus.
When the anterior border of the vastus internus is raised from the crureus,
the inner surface of the shaft of the femur will be seen to be perfectly bare.
No muscular fibres arise from this bony surface. The fleshy mass of the
vastus internus may now, with advantage, be divided transversely about
two inches above the patella. The muscle can then be thrown inwards,
and its origin studied.
The vastus internus arises — (1) from the lower part of the
anterior intertrochanteric line of the femur; (2) from the line
leading from this, below the small trochanter, to the linea
aspera ; (3) from the inner lip of the linea aspera ; (4) from
224 THE LOWER LIMB
the upper part of the internal supracondyloid line as low
down as the opening in the adductor magnus ; (5) from the
rounded tendon of the adductor magnus. The fleshy fibres
are directed downwards and forwards, and end in the common
tendon of the quadriceps muscle. By this it is inserted into
the patella, and becomes connected with the capsule of the
knee-joint. It is supplied by the anterior crural nerve.
The Crureus (musculus vastus intermedius) covers the
anterior and outer aspects of the shaft of the femur, from
both of which, as well as from the lower part of the external
intermuscular septum, it takes origin. It is inserted into the
patella through the medium of the common tendon. It is
supplied by the afiterior crural nerve.
Common Tendon of the Quadriceps. — It should now be
noticed that the common tendon of the quadriceps muscle
closes the knee-joint above the patella. It is inserted into
the upper border of that bone, and is intimately connected
with the capsule of the knee-joint. Some fibres are carried
downwards into the ligamentum patellae upon the surface of
the patella. A pouch of synovial membrane is prolonged
upwards beyond the level of the patella, between the quadri-
ceps and the bone. Into this some of the lower and deeper
fasciculi of the crureus muscle are inserted. They constitute
the sabcrureus muscle (musculus articularis genu).
The crureus should be divided in a vertical direction, so as to bring this
little muscle into view, and at the same time the long, slender nerve-
filament which runs along the inner border of the crureus may be traced
to the subcrureus and the synovial membrane of the knee-joint.
The ligame?itum patellce, which connects the patella with
the anterior tubercle of the tibia, and through which the
quadriceps is attached to that bone, will be studied in con-
nection with the knee-joint.
INNER SIDE OF THE THIGH.
The group of adductor muscles on the inner aspect of the
thigh, together with the blood-vessels and nerves associated
with them, must next be dissected. In this dissection the
following are the structures which are displayed : —
INNER SIDE OF THE THIGH 225
Muscles,
Pectineus.
Adductor longus.
Adductor brevis.
Adductor magnus.
Gracilis.
Obturator externus.
... f Profunda femoris and its branches.
Arteries, ( obturator.
., f The two divisions of the obturator.
t\ PI" VPS ~\
' \ Occasionally the accessory obturator.
The adductor muscles are disposed in three strata. The
superficial stratum is formed by the adductor longus and the
pectineus, which lie in the same plane. Above they are
placed side by side, but below, as they approach their inser-
tions, they are separated from each other by a narrow
interval. The seco?id stratum is formed by the adductor
brevis ; and the t/iird, or deep layer, by the adductor magnus.
The gracilis muscle, also an adductor, extends along the inner
aspect of the thigh. It is a long strap-like muscle, applied
against the adductor brevis and adductor magnus. Inter-
posed between these muscular layers, are the two divisions of
the obturator nerve. The anterior division is placed between
the superficial and middle layers, whilst the posterior division
lies between the middle and deep layers. In other words,
the two divisions of the nerve are separated from each other
by the adductor brevis, which intervenes between them. At
the lower border of the adductor longus, a fine branch from
the anterior division of this nerve makes its appearance to
take part in the formation of the sartorial nerve plexus
already dissected. The profunda artery and its branches are
also to be followed. For a part of its course this vessel is
placed between the anterior and middle muscular strata.
Adductor Longus. — This muscle is placed on the inner
side of the pectineus. It is somewhat triangular in shape,
being narrow at its origin and expanded at its insertion. It
arises by a short, but strong, tendon from the front of the
body of the pubis, immediately below the pubic crest (Fig.
61, p. 163), and it is inserted into the inner lip of the linea
aspera of the femur by a thin, tendinous expansion. It is
supplied by the anterior division of the obturator nerve.
Dissection. — The adductor longus may now be reflected. Divide it
close to the round tendon of origin, and throw it outwards. In doing this
be careful of the anterior division of the obturator nerve, which lies under
cover of it, and gives to it its nerve of supply. On approaching the linea
VOL. I — 15
226
THE LOWER LIMB
aspera of the femur its aponeurotic tendon will be found intimately con-
nected with the vastus internus in front and with the adductor magnus
behind. Separate it from these as far as possible, in order that the
profunda femoris vessels may be fully displayed as they proceed behind it.
Arteria Profunda Femoris. — This large vessel is the chief
artery of supply to the muscles of the thigh. It arises in
Scarpa's triangle from the outer and posterior aspect of the
femoral artery, about an inch and a half below Poupart's
Rectus femoris (straight head of origin)
-/ jj* — -Rectus femoris (reflected head of origin)
— -Attachment .of ilio-femoral band Adductor longus (origin)
Semimembran-
osus (origin)
Quadratus
femoris (origin)
Biceps and
semitendinosus
(origin)
Pyramidalis abdominis (origin)
\ Rectus abdominis (origin)
Gracilis (origin)
Adductor brevis (origin)
Fig. 8o. — Muscle-Attachments to the Outer Surface of the Pubis and Ischium.
ligament. At first it is placed on the iliacus, but it inclines
inwards as it proceeds downwards, and thus it crosses behind
the femoral artery,, and comes to lie on the pectineus.
Reaching the upper border of the adductor longus, it passes
behind that muscle, and is continued downwards close to the
shaft of the femur upon the adductor brevis and adductor
magnus. Numerous large branches spring from the profunda
femoris, so that it rapidly diminishes in size. Ultimately it
is reduced to a fine terminal twig, which turns backwards,
through the adductor magnus, and receives the name of the
INNER SIDE OF THE THIGH
227
Iliopsoas
External
circumflex
2nd, and
3rd perforat--'
ing arteries
1 st,
fourth perforatifig artery. The following, then, are the relations
of the profunda femoris : — (1) It lies on the iliacus to the
outer side of the femoral artery. (2) It rests on the pectineus,
behind the femoral artery, but separated from it by the femoral
vein. (3) It is placed on the adductor brevis, and lower down
on the adductor mag-
nus ; the adductor
longus lies in front of
this portion of the
vessel and separates
it from the femoral
artery. (4) The
terminal twig, called
the fourth perforat-
ing artery, pierces
theadductor magnus
at the junction of
the middle and
lower thirds of the
thigh.
The branches which
spring from the pro-
funda femoris are : —
the two circumflex
arteries, the four per-
forating arteries, and
some muscular
branches.
The external cir-
cumflex arises from
the outer aspect of
the profunda, close
to its origin. It has
already been followed
to its distribution
(p. 220). The internal circumflex, which takes origin at
the same level, but from the inner and back aspect of the
profunda, will be studied when the pectineus muscle is re-
flected. The muscular branches are irregular both in origin
and size. They supply the adductor muscles, and give twigs
which pierce the adductor magnus to reach the hamstring
muscles.
Femoral artery
Obturator extern us
Profunda
femoris
Internal
circumflex
Pectineus
Adductor
brevis
Adductor
magnus
Adductor
iongus
4th perforating
artery
Opening in
adductor magnu:-
Anastomotic
artery
Femoral artery
Fig. 81. — Profunda Femoris Artery and
its Branches.
228 ' THE LOWER LIMB
The internal circumflex artery frequently arises from the
common femoral trunk.
Perforating Arteries. — These arise in series from the
main trunk, and pass backwards through the adductor muscles
to the back of the thigh. They may be recognised from the
close relation which they bear to the linea aspera of the femur.
The first perforating artery (arteria perforans prima) comes off at
the level of the lower border of the pectineus. It proceeds
backwards through the adductor brevis and adductor magnus.
The second perforating artery (arteria perforans secunda) takes
origin a short distance lower down, or perhaps by a common
trunk, with the first perforating. It pierces the same muscles,
viz., the adductor brevis and adductor magnus. The third
perforati?ig (arteria perforans tertia) springs from the profunda
below the adductor brevis, and passes backwards through the
adductor magnus. The fourth perforati?ig, as we have noted,
is the terminal branch of the profunda femoris, and pierces
the adductor magnus.
The chief nutrient artery to the femur may come from either
the second or the third perforating branch. A second nutrient
twig is frequently derived from the fourth perforating artery.
When the adductor magnus is more fully exposed, it will
be seen that the perforating arteries, as they pierce its tendon,
have a series of fibrous arches thrown over them.
Pectineus. — This muscle is placed between the adductor
longus and the ilio-p'soas. It is flat and somewhat broader at
its origin from the brim of the pelvis than at its insertion
into the femur. It has a fleshy origin, from the ilio-pectineal
line, and from the surface of the innominate bone in front
of it (Fig. 6 1, p. 163). Some fibres are likewise derived
from Gimbernat's ligament. It descends obliquely outwards
and backwards, and gains insertion into the femur behind
the small trochanter, and to a certain extent also into the
line which leads from this prominence down to the linea
aspera. It is supplied by the a?iterior crural ?ierv.e.
Dissection. — The pectineus may be detached from its origin, and thrown
downwards and outwards. In separating the muscle from the pubis the
dissector must bear in mind that in some cases an accessory obturator nerve
descends into the thigh, over the brim of the pelvis, and under cover of its
outer margin. Care must also be taken not to injure the anterior division
of the obturator nerve which lies behind it, or the internal circumflex
artery which passes backwards in contact with its outer border.
The Accessory Obturator Nerve when present arises within the
INNER SIDE OF THE THIGH
229
urator externus
Obturator interims
Quadratus
femoris
abdomen from the obturator trunk near its origin. In the thigh it gives
a branch to the hip-joint and joins the anterior division of the obturator
nerve. It is very rare to find a twig given to the pectineus either by it
or by the trunk of the obturator nerve itself.
Internal Circumflex Artery (arteria circumflexa femoris
medialis). — This vessel arises from the inner and back aspect
of the profunda femoris at the same level as the origin of
the external circumflex. It
proceeds backwards between
the psoas and pectineus, and
then between the upperborder
of the adductor brevis and the
obturator externus to gain the
back ot the limb. Close to the
small trochanter of the femur
it divides into two terminal
branches — a transverse and
an ascending. From the
main trunk before it divides
are given off several muscular
branches to the adjoining mus-
cles, and an articular branch,
which enters the hip -joint
through the cotyloid notch.
The terminal branches of
the internal circumflex have
already been examined in the
dissection of the gluteal
region (p. 171).
Branches of the Femoral Artery. Fig. 82. —Back aspect of Upper Portion
—In every region of the thigh the Qf Femur with the Attachments of
dissector has met with branches of Muscles mapped out.
the femoral artery. It is well now
that he should revert to this vessel and study its branches in the order in
which they arise. The following Table may aid him in doing this : —
' Superficial pudic. \
Superficial epigastric. !- Superficial inguinal.
Superficial circumflex iliac.
Deep external pudic.
External circumflex.
Femoral.
1 Profunda, or deep
femoral.
Muscular.
^ Anastomotica magna.
Internal circumflex.
First perforating.
Second perforating. \ Nutrient.
Third perforating.
Fourth perforating, or terminal.
1— 15 a
23°
THE LOWER LIMB
Adductor Brevis. — This muscle lies behind the adductor
longus and the pectineus. It arises below the origin of the
adductor longus from the anterior aspect of the body and the
Anterior superior I
spine of ilium~
Tensor fasciae /"Jjfl
femoris iU
Sartorius
Anterior inferior
spine of ilium
Iliacus
Psoas
xterior iliac vessels
Anterior crural ner\'e
Capsule of hip-joint, grooved
b>' ilio-psoas Pectineus
| Obturator
nerve
Profunda femoris
vessels
Vastus ex tern us
Femoral vessels and
long saphenous nerve
Crureus -
\v\\
Rectus femoris — AA-A
—Sartorius
FIG. 83. — Dissection of the Front of the Thigh. The hip-joint has been
exposed by removing portions of the muscles which lie in front of it.
descending ramus of the pubis (Fig. 6 1 , p. 1 6 3 ). As it descends *
it inclines backwards and outwards, and it is inserted behind
the pectineus into the whole length of the line which extends
from the small trochanter to the linea aspera (Fig. 82, p. 229).
It is supplied by the obturato7- fierve.
IXXER SIDE OF THE THIGH
23x
Dissection. — Reflect the adductor brevis by cutting it close to its origin,
and throwing it downwards and outwards. The posterior division of the
obturator nerve is now exposed, and should be traced upwards to the
thyroid foramen, and downwards to its distribution upon the adductor
Obturator Nerve (nervus obturatorius). — The obturator
A: :
Accessory obturator
nerve.
Obturator nerve.
Obturator internus.
Obturator externus.
Pyriformis muscle.
Gluteus maximus.
Quadratus femoris.
If. Adductor magnus.
P. Pectineus.
Dbt.
0.1.
).E.
Py.
Ma.
Q-
A.B. Adductor brevis.
A. L. Adductor longus.
G. Gracilis.
X. Branch to hip-joii
IC. Internal circumfl
artery.
i. Cutaneous branch
2. Twig to walls
femoral artery.
Branch to kne
ioint.
Fig. 84. — Diagram to illustrate the distribution of the Obturator
Nerve and the general disposition of the Adductor Muscles
of the Thigh (Patersom.
nerve is a branch of the lumbar plexus, and escapes from the
pelvis by passing with its companion vessels through the upper
part of the thyroid foramen of the innominate bone. While
still within the foramen it divides into an anterior and a
posterior division.
The anterior division of the obturator nerve enters the thigh
over the upper border of the obturator externus musde, and
232
THE LOWER LIMB
proceeds downwards upon the anterior surface of the adductor
brevis. In front of it are the pectineus and adductor longus
muscles. It gives branches to three muscles, viz., the adductor
longus, the adductor brevis, and the gracilis. Very rarely it
will be observed to supply a twig to the pectineus. In addi-
tion to these it supplies an articular branch to the hip-joint
Anterior crural nerve
Crural branch of
genito-crural
Femoral sheath
Crural canal
Obturator artery and nerve
Adductor longus
Fig. 85.
-Dissection to show the Structures surrounding the Thyroid
Foramen of the Innominate Bone.
(Fig. 84, x ) ; a fine twig which appears at the lower border of
the adductor longus to join the sartorial plexus (Fig. 84, 1); and
a terminal twig which goes to the femoral artery — (Fig. 84, 2) —
and breaks up into fine filaments upon its walls.
The t>0^terior ^fjn^'n^ of the obturator nerve as it enters the
thigh pierces the upper border of the obturator externus. It
extends downwards between the adductor brevis and the
adductor rrmgnns, and is chiefly expended in the supply of
the latter muscle. It gives also, however, a branch to the
INNER SIDE OF THE THIGH 253
obturator externus and an articular branch to the knee-joint
(Fig. 84, 3). The latter branch pierces the lower part of the
adductor magnus close to the linea aspera, and has already
been seen in the popliteal space lying upon the popliteal
artery.
Gracilis. — This is a long, strap -like muscle, which is
situated along the inner aspect of the thigh and knee. It springs
by a thin tendon from the lower half of the body of the pubis,
close to the symphysis, and also from the upper half of the
pubic arch (Fig. 61, p. 163). It ends in a slender, rounded
tendon which inclines forwards below the knee, and then ex-
pands to find insertion into the upper part of the inner surface
of the tibia, under cover of the tendon of the sartorius, and at
a higher level than the insertion of the semitendinosus (Fig.
68, p. 187). A synovial bursa separates the expanded tendon
of the gracilis from the internal lateral ligament of the knee-
joint, and is prolonged above it, so as to intervene between it
and the tendon of the sartorius. The gracilis is supplied by
the anterior division of the obturator nerve.
Adductor Magnus. — This is one of the most powerful
muscles of the thigh. It forms a flat fleshy mass, which
springs from the anterior surface of the entire length of the
pubic arch, and from the lower part of the tuberosity of the
ischium (Fig. 61, p. 163). The fibres which arise from the
pubic arch spread out as they approach the back of the femur.
The upper fibres are nearly horizontal in their direction ;
below this they descend with increasing degrees of obliquity.
They are inserted into the posterior surface of the femur,
immediately internal to the gluteal ridge, into the linea aspera,
and into a small portion of the upper part of the internal
supracondyloid ridge (Fig. 82, p. 229). The fibres which take-
origin from the ischial tuberosity descend almost vertically and
form the thick inner border of the muscle. In the lower third
of the thigh they end in a strong, rounded tendon, which is in-
serted into the adductor tubercle on the inner tuberosity of the
femur (Fig. 95, p. 262). This tendon is further attached to
the femur by the internal intermuscular septum which stretches
between it and the internal supracondyloid line. Close to the
linea aspera the dissector' will notice that fibrous arches are
formed in connection with the insertion of the adductor
magnus for the passage of the perforating arteries. The
opening through which the femoral artery enters the popliteal
234 THE LOWER LIMB
space lies in series with these. It is a gap between the two
portions of the muscle, and is situated in the lower third of
the thigh.
The adductor magnus has a double nerve supply. Be-
hind, it is supplied by branches from the great sciatic, whilst
in front it receives the greater part of the posterior division
of the obturator.
Dissection. — The adductor magnus should now be detached from its
origin, in order that the obturator externus muscle and the obturator artery
may be more fully examined.
Obturator Externus. — The obturator externus is a flat, fan-
shaped muscle, which is placed over the front of the thyroid
foramen of the innominate bone. It springs from the inner
half of the membrane which closes the foramen, and also from
the inner and lower part of its bony margin (Fig. 61, p. 163).
It proceeds backwards and outwards below the neck of the
femur and the capsular ligament of the hip-joint, and ends in
a stout tendon which obtains insertion into the digital fossa
at the root of the great trochanter (Fig. 82, p. 229). This
tendon has already been noticed in the dissection of the
gluteal region. The obturator externus is supplied by the
posterior division of the obturator ?ierve.
Obturator Artery (arteria obturatoria). — The obturator
artery appears in the thigh through the upper part of the
thyroid foramen of the innominate bone. It at once divides
into two terminal branches, which diverge from each other,
and form an arterial circle upon the thyroid membrane,
under cover of the obturator externus. This muscle must
therefore be detached in order that these vessels may be
followed. Both branches give twigs to the neighbouring
muscles, whilst the outer branch (i.e. the branch which runs
round the outer side of the foramen) sends an articular twig
through the cotyloid notch of the acetabulum into the hip-
joint. When the joint is opened this twig may be followed
in a well-injected subject, along the ligamentum teres, into
the head of. the femur.
Psoas and Iliacus. — These muscles arise within the
abdomen and enter the thigh behind Poupart's ligament. A
tendon appears on the outer side of the psoas, and into this
the fibres of the iliacus are for the most part inserted. The
conjoined tendon of the ilio-psoas is implanted into the small
trochanter of the femur, but a certain proportion of the
INNER SIDE OF THE THIGH 235
fleshy fibres of the iliacus obtain direct insertion into the
shaft of the femur below and in front of that prominence
(Fig. S2, p. 229).
Dissection. — Divide the femoral vessels, and the anterior crural nerve,
about an inch below Pouparts ligament, and having tied them together
with twine throw them downwards. Now cut through the sartorius and
the rectus femoris about two inches from their origins and turn them aside.
The tendon of the ilio-psoas must next be detached from its insertion and
the muscle thrown upwards. This will expose the anterior surface of the
capsule of the hip-joint. An intervening bursal sac will also be displayed.
Open this and ascertain its extent by introducing the finger. It facilitates
the play of the ilio-psoas upon the front of the hip-joint, and in some rare
cases it will be found to be directly continuous with the synovial membrane
of this articulation through an aperture in the capsular ligament. The
intimate connection which exists between the capsule of the hip-joint and
the tendon of the gluteus minimus, the reflected head of the rectus femoris,
and the deep layer of the ilio-tibial band, should be noticed. Lastly, reflect
the tensor fascne femoris, and carefully clean the capsule of the hip-joint.
HIP-JOINT.
It is necessary that the hip-joint (articulatio coxae) be
studied at this stage, as the further dissection of the limb can
only be satisfactorily carried out after its removal from the
trunk.
The hip-joint is the most perfect example of an enarthrodial or ball and
socket joint in the body. It does not allow so free a range of movement
as that which takes place at the shoulder-joint, but what it loses in this
respect it gains in strength and stability. Its great strength and security
depend : ( 1) upon the depth of the cotyloid cavity and the thorough manner
in which the head of the femur is received into it ; (2) upon the tension and
power of the ligaments ; (3) upon the length and oblique direction of the
neck of the femur ; and (4) upon atmospheric pressure.
The ligaments in connection with the hip-joint are : —
1. Capsular. 3. Cotyloid.
2. Ligamentum teres. 4. Transverse.
The capsular ligament and the ligamentum teres are
attached to both bones entering into the construction of the
joint. The transverse and the cotyloid ligaments are con-
nected with the acetabular cavity ; the former partially fills
up the notch or deficiency in its inferior part, whilst the latter
surrounds its circumference in a ring-like fashion, and serves
to still further deepen it.
Capsular Ligament (capsula articularis). — This is exceed-
236
THE LOWER LIMB
ingly strong, and surrounds the joint on all sides. Superiorly,
it is attached around the acetabulum ; above and behind,
directly to the innominate bone, just outside the rim of the
cavity ; in front, to the outer aspect of the cotyloid ligament ;
and below, to the transverse ligament. Inferiorly, it clasps
the neck of the femur. In front, it is attached to the whole
length of the anterior intertrochanteric line, and to the root
Anterior inferior
spine of ilium
Cotyloid ligament
Head of femur
Pubo-femoral ligament
V__ Thyroid
1 )/ membrane
Pubo-femoral ligament
Fig. 86. — Dissection of Hip-joint from the front.
of the great trochanter. This attachment is very firm and
strong. Behind and below, it falls short of the posterior
intertrochanteric line by about half an inch, and it presents
a weak attachment to the posterior and inferior surfaces of
the neck of the femur.
If the capsule of the hip-joint has been carefully cleaned it
will be seen that the fibres which compose it run in two
different directions. The majority pass in a longitudinal
direction from one bone to the other ; others, however, may
be observed to take a more or less transverse or circular
THE HIP-JOINT 237
course. The latter are only seen to advantage on the
posterior aspect of the capsule, whilst the longitudinal fibres
are massed on the front of the joint. Certain thickened
portions of the capsule, with more or less distinct attach-
ments, are described under special names. These are : —
1. Iliofemoral. 3. Ischio-capsular.
2. Pubo-femoral. 4. The zonular band.
The Mo-femoral band (ligamentum ilio-femorale) is placed
over the front of the articulation, and constitutes the thickest
and most powerful part of the capsule. It springs from the
anterior inferior spine of the ilium, and from a depressed
surface on the bone immediately to the outer side of this.
As it proceeds downwards in the capsule, it divides into two
limbs, which diverge slightly from each other. The outer
portion is implanted into the upper part of the anterior
intertrochanteric line, close to the great trochanter ; the
inner portion, longer and almost vertical in direction,
descends to find attachment into the lower end of the
anterior intertrochanteric line. The interval between these
two diverging parts of this ligament is occupied by a thinner
portion of the capsule. The ilio-femoral band is sometimes
called the Y-shaped ligament, but, in making use of this term,
remember that the shape it presents is that of an inverted Y.
The pubo-femoral band (ligamentum pubocapsulare) is the
name applied to several fasciculi of no great strength, which
spring from the pubic bone and the thyroid membrane, and
join the lower and anterior aspect of the capsule. In cases
where the bursa under the ilio-psoas is continuous with the
synovial membrane of the joint, the aperture of communica-
tion is placed between this band and the ilio-femoral band.
The ischio-capsular band (ligamentum ischio- capsular e) is
stronger. It takes origin from the ischium below the
acetabulum, and passes into the lower and posterior aspect of
the capsule.
The zonular band (zona orbicularis) is composed of circular
fibres, and will be observed on the posterior aspect of the
capsule. It encircles the neck of the femur behind and
below, but is lost as it is traced forwards towards the upper
part and the front of the capsule.
The dissector has already observed the close connection
which is exhibited between the capsule of the hip-joint and
238 THE LOWER LIMB
the tendons of the gluteus minimus, and the reflected head of
the rectus. Reinforcing fibres are contributed to the capsule
by both of these tendons.
Movements permitted at the Hip-joint. — Before the capsule of the
joint is opened the range of movement which is permitted at the hip-joint
should be tested. Flexion, or forward movement, is very free, and is only
checked by the anterior surface of the thigh coming into contact with the
abdominal wall. Extension, or backward movement, is limited by the
ilio-femoral band. This powerful ligament has a most important part to
play in preserving the upright attitude with the least possible expenditure
of muscular exertion. In the erect posture the line of gravity falls slightly
behind the line joining the central points of the two hip-joints. In the
upright attitude the ilio-femoral bands are tight, and prevent the pelvis
from rolling backwards on the heads of the femora. Abduction, or outward
movement of the thigh, is checked by the pubo-femoral band. Adduction,
or inward movement {e.g. , as in crossing one thigh over the other), is limited
by the upper portion of the ilio-femoral band and the upper part of the
capsule. Rotation inwards tightens the ischio-capsular band, and is therefore
in a measure restrained by it. Rotation outwards is limited by the outer
portion of the ilio-femoral band. In circumduction, which is combination
of the movements of flexion, abduction, extension, and adduction, different
parts of the capsular ligament are tightened at different stages of the
movement.
The flexor muscles, which operate on the femur at the hip-joint, are
chiefly — (i) the ilio-psoas, and (2) the pectineus ; the extensors are — (1)
the gluteus maximus, and (2) the gluteus medius ; the abductors — (1) the
upper part of the gluteus maximus, (2) the gluteus medius, (3) the gluteus
minimus ; the adductors — (1) the three adductors, (2) the pectineus, (3) the
lower part of the gluteus maximus, and (4) the obturator externus ; the
inward rotators — (1) the anterior part of the gluteus medius, (2) the anterior
part of the gluteus minimus, (3) the tensor fasciae femoris, and (4) the ilio-
psoas ; the outward rotators — (1) the two obturator muscles, (2) the gemelli,
(3) the pyriformis, (4) the quadratus femoris, and (5) the gluteus maximus.
Dissection. — The hip-joint may now be opened, and in doing this it is
advisable to remove in the first instance the whole capsule, with the
exception of the ilio-femoral band. The enormous strength of this portion
of the capsule can in this way be appreciated. It is fully a quarter of an
inch thick, and a strain varying from 250 lbs. to 750 lbs. is required for
its rupture (Bigelow). It is very rarely torn asunder in dislocations, and
consequently the surgeon is enabled in most cases to reduce the displace-
ment by manipulation. The ilio-femoral band may now be removed.
Cotyloid Ligament (labrum glenoidale). — This is a firm
fibro-cartilaginous ring, which is fixed to the brim or margin of
the acetabulum. It bridges across the notch, and thus com-
pletes the circumference of the cavity, deepens it, and at the
same time narrows slightly its mouth. The cotyloid ligament
fits closely upon the head of the femur, and, acting like a
sucker, exercises an important influence in retaining it in
place. Both surfaces are covered by synovial membrane ; its
THE HIP-JOIXT
239
free margin is thin, but it is much thicker at its attachment
to the acetabular brim.
Transverse Ligament (ligamentum transversum acetabuli).
— This ligament is composed of some transverse fibres which
bridge across the notch in the inferior part of the acetabulum.
Ischial spine
Cotyloid ligament
lgamentumj^fv' c
teres ' '^l&tf'V
Capsule of
joint divided
and thrown
outwards
Transverse ligament
Retinacula
Fig. 87. — Dissection of Hip-joint from behind. The bottom of the
Acetabulum has been removed to show the Ligamentum teres.
and are attached to its margins. The more superficial of
these fibres are more or less directly connected with the
deep surface of the cotyloid ligament as it stretches across
the notch, but they do not fill up the entire gap ; a narrow
interval is left between the transverse ligament and the bone
for the entrance of blood-vessels and nerves into the joint.
Ligamentum Teres (ligamentum teres femoris). — The liga-
24o THE LOWER LIMB
mentum teres is not round, as its name might lead one to
expect, but somewhat flattened and triangular in shape. Its
narrow femoral extremity is implanted into the upper margin
of the pit which marks the head of the femur, whilst its flattened
acetabular end is bifid, and is fixed to the margins of the notch
in the lower part of the acetabulum, and also to the transverse
ligament. This attachment can be defined by removing the
synovial membrane and some areolar tissue. The ligamentum
teres is completely surrounded by synovial membrane, and a
small artery runs along it to the head of the femur. It is
difficult to understand the part which the ligamentum teres
plays in the mechanism of the hip-joint. It presents very
different degrees of strength in different individuals. It
becomes very tense when the thigh is slightly flexed and then
adducted.
Synovial Membrane and Interior of the Joint. — A mass
of soft fat occupies the non-articular bottom of the acetabular
cavity. Upon this the ligamentum teres is placed, and
blood-vessels and nerves enter it by passing through the
notch under cover of the transverse ligament. The vessels
come from the internal circumflex and the obturator arteries,
and the nerves come from the anterior division of the ob-
turator nerve and from the accessory obturator, when it is
present. A nerve-twig is also supplied to the back of the
joint by the nerve to the quadratus femoris.
The synovial membrane lines the interior of the capsule.
From this it is reflected on to the neck of the femur, and it
clothes the bone as far as the margin of the articular cartilage
which covers the head. Along the line of reflection some
fibres of the capsular ligament proceed upwards on the neck
of the femur and raise the synovial membrane in the form of
ridges. These fibres are termed the retinacula or cervical
ligaments.
These cervical ligaments are of some surgical importance. In intra-
capsular fracture of the neck of the femur they may escape rupture, and
they may then to some extent help to retain the fragments in apposition.
Hence examinations of this class of fracture must be conducted gently,
lest by rupturing this ligamentous connection the fragments be perma-
nently displaced.
At the acetabular attachment of the capsular ligament the
synovial membrane is reflected on to the cotyloid ligament
and invests both its surfaces. It also covers the articular
i
THE HIP-JOINT 241
surface of the transverse ligament and the cushion of fat
which occupies the bottom of the cavity. Lastly, it gives a
tubular investment to the ligamentum teres.
Removal of the Limb. — The limb may now be removed from the trunk
by dividing the ligamentum teres. It should then be taken to one of the
tables set aside for the dissection of separate parts. Before proceeding to
the dissection of the leg it is advisable to study the attachments of the
various muscles to the femur. The bulk of these may be removed, but a
small portion of each should be left, so that their connections may again
be revised, should it be found necessary to do so at a later period.
THE LEG.
Surface Anatomy. — The relation of the tibia and fibula
to the surface should be carefully investigated. The sharp
anterior border of the tibia or shin does not form a projection
visible to the eye, but nevertheless it is subcutaneous, and
can be very distinctly felt when the finger is passed along it.
It pursues a slightly sinuous course, and in its lower part
becomes rounded-off and indistinct. The broad, flat, internal
surface of the shaft of the tibia is also subcutaneous
below the level of the insertion of the sartorius, and the
inner border of the bone can be followed by the finger
throughout its entire length. The fibula is more deeply
placed, and the upper half of its shaft cannot be felt
from the surface owing to the manner in which it is sur-
rounded by muscles. The head of the bone, however, is very
evident where it articulates with the outer and back part of
the tuberosity of the tibia ; and for a short distance above the
external malleolus the shaft of the fibula is subcutaneous over
a triangular area which is interposed between the peroneus
tertius muscle in front and the peroneus longus and peroneus
brevis muscles behind.
The two malleoli form marked projections in the region of
the ankle. The internal malleolus is the broader and more
prominent of the two ; it does not descend so low down,
however, and when viewed from the front it is observed to
reach farther forwards. This latter appearance is due to its
greater breadth, because when examined from behind the
posterior borders of the two projections are seen to occupy
very nearly the same plane.
vol. 1 — 16
242 THE LOWER LIMB
On the posterior aspect of the leg the prominence known
as the " calf of the leg " is visible. This is largely due to the
fleshy bellies of the gastrocnemius muscle. Below the calf
and immediately above the heel the powerful tendo Achillis
can be felt. In front of this tendon a slight hollow is apparent
on either side of the limb.
As the skin is reflected from the dorsum of the foot
during the dissection of the leg, the present opportunity
should be seized for studying the surface anatomy of the foot.
The individual tarsal bones cannot be recognised through the
integument which covers the dorsum of the foot ; but if the
foot be powerfully extended the head of the astragalus will
be brought into view in the shape of a slight prominence.
The margins of the foot require careful study, because it is
by the recognition of certain bony projections in these that
the surgeon is enabled to determine the point at which to
enter the knife when he is called upon to perform partial
amputation of the foot. Examine the iimer margin first.
Begin behind at the projection formed by the internal tuber-
osity of the os calcis, and proceed forwards. About one inch
below the internal malleolus the inner edge of the sustenta-
culum tali may be recognised, and about one inch or a little
more in front of this we recognise the tubercle of the scaphoid.
Then comes the internal cuneiform bone, and this is suc-
ceeded by the first metatarsal bone. None of these bony
points can be said to form distinct prominences on the
surface of a well- developed foot. In order to distinguish
them the inner margin of the foot must be judiciously
manipulated by the fingers. On the outer ??iargin of the foot
the tubercle on the base of the fifth metatarsal bone stands
out as a distinct landmark. Behind this is the cuboid, and
still farther back the outer surface of the os calcis, which is
almost completely subcutaneous. When present in a well-
developed form the peroneal tubercle on this surface may be
distinguished about one inch below and a little in front of the
external malleolus. If the foot be strongly inverted the anterior
end of the os calcis will be seen to project on the surface.
Subdivision of the Leg into Kegions. — In the dissection of
the leg four distinct regions may be recognised, viz. : —
I. An anterior tibio-fibnlar region, in which are placed those structures
which lie in front of the interosseous membrane, and between the
two bones of the leg.
THE LEG 243
2. A tibial region, corresponding to the subcutaneous or inner surface of
the shaft of the tibia.
3. A peroneal region, which includes the parts in relation to the outer
surface of the fibula.
4. A posterior tibio-fibular region, in which are placed the parts on the
back of the leg which lie behind the interosseous membrane and the
two bones of the leg.
Anterior Tibio-Fibular Region — Dorsum of Foot.
The anterior tibio-fibular region should be dissected first,
and it is usual to conjoin with this the dissection of the
dorsum of the foot. The following parts are exposed in this
region : —
Anterior tibial vessels.
Anterior peroneal artery.
Anterior tibial nerve.
Recurrent articular branch
from the external popliteal
nerve.
Extensor brevis digitorum.
Dorsalis pedis artery.
Reflection of Skin.— To place the limb in a convenient position for
the dissection of this region, a block should be introduced beneath the
knee, and the foot should be extended and fastened firmly to the table by
means of hooks. The skin should be reflected from the tibial and peroneal
regions at the same time. Incisions : — (1) a vertical cut along the middle
line of the leg and dorsum of the foot to the base of the middle toe ; (2) a
transverse incision across the ankle-joint ; (3) a transverse incision across
the dorsum of the foot at the roots of the toes.
The four flaps of skin thus mapped out must now be raised from the
subjacent fatty tissue, and the superficial veins and nerves dissected out.
Superficial Veins. — The venous arch on the dorsum of the
foot, which receives the digital veins, should in the first place
be dissected. From the inner extremity of this arch the
ititeriial saphenous vein will be seen to take origin, whilst from
its outer end the external saphenous vein proceeds. Trace
these vessels upwards. The former will be found to pass in
front of the internal malleolus, whilst the latter ascends behind
the external malleolus. Each is associated with the nerve
which bears its own name. %
Cutaneous Nerves. — -The following are the cutaneous
nerves which must be secured in this dissection : —
1— 16 «
I.
Superficial veins.
8.
2.
Cutaneous nerves.
9-
3-
Deep fascia, with its inter -
10.
muscular septa, and annular
n.
ligaments.
4-
Tibialis anticus.
5-
Extensor longus digitorum.
12.
0.
Peroneus tertius.
*3-
7-
Extensor longus hallucis.
244 THE LOWER LIMB
i. A branch from the external popliteal.
2. External saphenous.
3. Internal saphenous.
4. Musculocutaneous.
5. Anterior tibial.
The branch from the external popliteal frequently arises in
common with the ramus communicans fibularis. It turns
forwards, and is distributed upon the outer and anterior
aspect of the leg in its upper part. The external saphenous
nerve can be readily found. It reaches the outer margin of
the foot by passing behind the external malleolus in company
with the vein of the same name. Trace it forwards, and it
will be found to end upon the fibular side of the little toe.
On the dorsum of the foot a connecting twig passes between
the external saphenous and the outer division of the musculo-
cutaneous nerve. The internal or long saphenous nerve should
be looked for in front of the inner malleolus. It descends in
company with the internal saphenous vein. It can with care
be followed half-way along the inner margin of the foot, but
there it ends. Above the ankle-joint several minute twigs
from this nerve may be found passing forwards to reach the
front of the leg.
The cutaneous portion of the ?nusculo-cutaneous nerve appears
in the lower third of the leg. It pierces the deep fascia a
short way to the outside of the middle line of the limb.
Almost immediately it splits into an inner and an outer part.
The inner division extends forwards on the dorsum of the
foot, and sends one branch to the inner side of the great toe,
and a second to supply the adjacent sides of the second and
third toes. It likewise gives a number of twigs to the skin
upon the inner margin of the foot, and effects junctions with
the anterior tibial and internal saphenous nerves. The outer
division is smaller than the inner part. It gives several twigs
to the skin on the dorsum of the foot, communicates with
the external saphenous nerve, and then divides into two
branches, which supply the contiguous margins of the third,
fourth, and fifth toes. Therefore, with the exception of the
adjacent sides of the great toe and the second toe, which are
supplied by the anterior tibial nerve, and the outer side of
the little toe, which is supplied by the external saphenous
nerve, the musculo-cutaneous nerve furnishes twigs to the two
margins of each of the toes (Fig. 70, p. 198).
Very frequently the distribution of the musculo-cutaneous
THE LEG 245
nerve is more restricted, and in these cases the external
saphenous nerve will, in all probability, be found to supply
the outer two and a half toes.
The anterior tibial nerve, or rather its internal terminal branch*
pierces the deep fascia on the dorsum of the foot in the interval
between the first and second metatarsal bones. It receives a
communicating branch from the inner part of the musculo-cuta-
neous, and ends by dividing into two twigs, which go to supply
the adjacent margins of the great toe and the second toe.
Deep Fascia. — The fatty superficial fascia should be re-
moved in order that the deep fascia may be displayed. This
aponeurosis does not form a complete investment for the leg.
It is absent over the internal subcutaneous surface of the
tibia, and is attached to the anterior and internal borders of
that bone. It is also absent over the triangular subcutaneous
surface on the lower part of the fibula, being attached to the
ridges which limit this area in front and behind. It is not
equally dense throughout. In the upper part of the front of
the leg it is thick and strong, but it thins as it is traced down-
wards, and on the dorsum of the foot it becomes exceedingly
fine. Its great strength in the upper part of the front of the
leg is due to the fact that here it gives origin to subjacent
muscles. In the neighbourhood of the ankle-joint it forms
the thickened bands or annular ligaments which retain the
tendons in position during the action of the muscles. Two
of these may be examined at this stage, viz., the anterior and
the external annular ligaments.
The anterior annular ligament consists of two portions — an
upper and a lower. The upper part is a strong, broad band
which stretches across the front of the leg immediately above
the ankle-joint. By one extremity it is attached to the fibula,
and by the other to the tibia. The lower part is placed over
the ankle-joint. Externally it presents the appearance of a
narrow, well-defined band, which is fixed firmly to the anterior
part of the os calcis. As this is traced inwards it will be
observed to divide into two diverging limbs. Of these the
upper is attached to the inner malleolus, whilst the lower
passes to the inner margin of the foot, and becomes connected
with the plantar fascia. The different parts of the anterior
annular ligament are continuous with the deep fascia, but
can readily be distinguished on account of their greater
density and thickness.
246
THE LOWER LIMB
TIBIA
The external annular liganient is short and narrow, and
bridges over the hollow between the external malleolus and
the posterior prominence of the os calcis.
Intermuscular Septa. — As the deep fascia of the leg passes
backwards over the fibular region, two strong inter-muscular
septa are given off from its deep surface. These are dis-
tinguished as the anterior and posterior peroneal septa.
The anterior peroneal septum intervenes between the peroneal
muscles and the extensor muscles, and is attached to the
anterior border of the fibula. The posterior pero?ieal septum
is interposed between the
peroneal muscles and the
muscles on the back of
the leg, and is attached to
the external border of the
fibula. The leg is thus sub-
divided into three osteo-
fascial compartments, cor-
responding to the anterior
tibio-fibular, peroneal, and
posterior tibio-fibular re-
gions. The anterior com-
part??ient is bounded by the
investing deep fascia, the
anterior peroneal septum,
Fig. 88.— Diagrammatic representation of , anterior nart nf the
the Fascia of the Leg. The fascia of the me anterl0r part Ot tne
tibialis posticus is more a muscular inner Surface of the fibula
aponeurosis than a true fascial septum ; (that part which lies in
but it is convenient for descriptive pur- f . f h interosseous
poses to regard it as one of the partitions.
line), the interosseous mem-
brane, and the external surface of the tibia. The outer
compartment is bounded by the external surface of the
fibula, the investing fascia, and the two peroneal septa. The
posterior compart?nent is much the largest, and its walls are
formed by the posterior surface of the tibia, the hinder part
of the internal surface and the whole of the posterior surface
of the fibula, the interosseous membrane, the posterior peroneal
septum, and the investing deep fascia. This compartment
is still further subdivided by two partitions ; but these will be
studied later on.
Dissection. — The anterior compartment of the leg should now be opened
by removing the deep fascia. The two portions of the anterior annular
THE LEG
247
ligament, however, must
be retained, and their
borders should be separ-
ated artificially by the
knife from the deep
fascia, with which they
are continuous. In the
upper part of the leg
it will be found impos-
sible to raise the fascia
from the subjacent mus-
cles without lacerating
their surfaces. It should
therefore be left in posi-
tion. At a lower level
it can readily be separ-
ated. Divide it in a
longitudinal direction
midway between the
tibia and fibula. On
throwing the inner piece
inwards, its firm at-
tachment to the anterior
border of the tibia will
become evident ; and
as the outer piece is
turned outwards, the
anterior peroneal sep-
tum will come into view.
Contents of the
Anterior Tibio-fibu-
lar Compartment.
— Four muscles are
brought into view
by the above dis-
section, viz., the
tibialis anticus, the
extensor longus
digitorum, the ex-
tensor longus hal-
lucis, and the pero-
neus tertius. The
tibialis anticus lies in
relation to the tibia ;
the exte?isor longus
placed
the fibula ;
and on separating these
- Patella
Ligamentum patellae
External popliteal nerve
Head of fibula
Peroneus longus
Musculocutaneous nerve
\ Anterior tibial artery
f and nerve
Extensor longus digitorum
„zl I ibialis anticus
I — 1 ibia (subcutaneous surface)
— Peroneus brevis
Peroneus longus
Extensor longus hallucis
Fibula (subcutaneous surface)
eroneus tertius
Anterior annular ligament
(upper band)
Anterior annular ligament
(lower band)
Anterior tibial nerve and
«T\\ i«d_J« -m lienor nuiai nerv<
^V v\HJ dorsalis pedis artery
r^ — ^^^^*w — -^ ^^ PprmipiK fprtiiiQ I
I
Peroneus tertius tendon
digitorum
along
Fig.
89. — Dissection of the Anterior Tibio-Fibular
and Fibular Regions.
muscles from each other, the extensor
248 THE LOWER LIMB
longus hallucis will be observed in the interval between them.
The peroneus tertius lies upon the lower portion of the fibula,
and in most cases is incorporated with the extensor longus
digitorum. The anterior tibial vessels and nerve proceed
downwards in this compartment. At first they are deeply
placed, but as they approach the ankle they come nearer to
the surface.
Dissection. — To expose the anterior tibial vessels and nerve in their
entire course on the front of the leg, the tibialis anticus and the extensor
longus digitorum must be separated from each other along the line of a
strong intermuscular septum, which dips backwards between them, and
affords a surface of origin to each. The knife should be carried upwards
along the plane of this septum. By drawing aside the peroneus tertius
muscle, the anterior peroneal artery will be seen piercing the interosseous
membrane. It is a small artery which descends upon the lower end of the
fibula. As the structures in the anterior tibio- fibular compartment are
being exposed and cleaned, the dissector should at the same time carry on
the dissection of the dorsum of the foot. Here the tendons of the muscles
on the front of the leg must be followed to their insertions, and the extensor
brevis digitorum muscle defined. The dorsalis pedis artery and the anterior
tibial nerve should also be followed, and their branches traced to their
various destinations.
Tibialis Anticus (musculus tibialis anterior). — The tibialis
anticus is a powerful muscle, which takes origin from the lower
part of the external tuberosity of the tibia, and from the upper
half of the external surface of its shaft (Fig. 68, p. 187). It
likewise derives many fibres from the deep fascia which covers
it, from the fascial septum between it and the extensor longus
digitorum and the portion of the interosseous membrane on
which it rests. In other words, it springs from the structures
which form the walls of the inner portion of the osteo-fascial
compartment in which it lies.1 A strong tendon issues from
its fleshy belly in the lower third of the leg, and this reaches
the dorsum of the foot by passing through both portions of
the anterior annular ligament. Here it inclines inwards, and,
turning round the inner margin of the foot, gains insertion by
two slips into the inner and lower part of the internal cunei-
form bone, and into the adjoining part of the base of the
1 To understand the attachments of the muscles of the leg, it is necessary
to bear in mind that the interosseous membrane, which stretches across the
interval between the two bones of the leg, and thus extends the surface of
origin for these muscles, is attached to the outer border of the tibia [i.e.,
between its outer and posterior surfaces) and to the interosseous line of the
fibula. This interosseous line traverses the inner surface of the fibula, so as
to divide it into an anterior and a posterior part. The anterior part gives
origin to the extensor muscles and the posterior part to the flexor muscles.
THE LEG
'49
first metatarsal bone. The tibialis amicus is supplied by the
a?iterior tibial nerve.
Extensor Longus Digitorum. — This muscle arises, for the
most part, from the structures which form the outer portion of
the wall of the anterior tibio-fibular compartment. Thus it springs
from the upper part of the outer tuberosity of the tibia, from
the head of the fibula, and from the anterior part of the inner
surface of the shaft of the fibula in its upper three-fourths (Fig.
68, p. 187). It also takes origin from a small portion of the
upper part of the interosseous membrane, the deep investing
Extensor longus digitorum
Peroneus brevis
Musculo
cutaneous nerve
Extensor longus hallucis
/ Anterior tibial
vessels and nerve
Plantaris
Peroneal vessels
Posterior tibial vessels and nerve
Fig. 90. — Transverse section through the Calf of the Leg.
fascia of the leg, the anterior peroneal septum, and the inter-
muscular septum, which dips backwards between it and the
tibialis anticus. The tendon of the extensor longus digitorum
descends in front of the ankle-joint, and, passing through the
anterior annular ligament (p. 256), divides into four pieces,
which diverge from each other on the dorsum of the foot to
reach the four outer toes. On the dorsum of the first phalanx-
each of the inner three slips is joined on the outer side by a
tendon from the extensor brevis digitorum.
The manner in which the four tendons of the extensor
250 THE LOWER LIMB
longus digitorum are inserted on the dorsal surfaces of the
four outer toes is so similar to that in which the correspond-
ing tendons of the fingers are attached, that a very brief
description will suffice. An expansion is formed on the
dorsal surface of the first phalanx ; this is joined by the
slender tendons of the lumbrical and interosseous muscles,
and divides into a central and two lateral slips. The central
slip is inserted into the base of the second phalanx, whilst
the stronger lateral slips are prolonged onwards, and, uniting
with each other, gain insertion into the base of the ungual
phalanx. The extensor longus digitorum is supplied by the
anterior tibial nerve.
Extensor Longus Hallucis. — The extensor longus hallucis
is placed in the interval between the tibialis anticus and the
extensor longus digitorum. In its upper part it is hidden from
view by these muscles, but near the ankle it comes to the surface.
It takes origin behind the extensor longus digitorum, from an
extremely narrow strip of the anterior part of the inner surface
of the shaft of the fibula in its middle two-fourths, and also from
the adjoining part of the interosseous membrane. Its tendon
crosses the lower part of the anterior tibial artery, and reaches
the dorsum of the foot by passing downwards in front of the
ankle-joint and through the anterior annular ligament (p. 256).
It is inserted into the dorsal aspect of the base of the ungual
phalanx of the great toe.1 It is not joined by the innermost
tendon of the extensor brevis digitorum. The extensor
longus hallucis is supplied by the anterior tibial nerve.
Peroneus Tertius. — This is a small muscle which is con-
tinuous at its origin with the extensor longus digitorum. It
arises from the lower fourth of the anterior part of the inner
surface of the fibula, and from a corresponding extent of the
interosseous membrane. It also receives fibres from the
lower part of the anterior peroneal septum which intervenes
between it and the peroneus brevis. Its slender tendon is
inserted into the dorsal surface of the expanded base of the
fifth metatarsal bone. It is supplied by the anterior tibial nerve.
Anterior Tibial Artery (arteria tibialis anterior). — The
anterior tibial artery is the smaller of the two terminal
branches of the popliteal. It takes origin on the back of the
leg, at the lower border of the popliteus muscle, and it gains
1 In most cases it likewise gives a slip to the base of the proximal phalanx.
THE LEG 251
the anterior tibiofibular compartment by passing forwards
through the opening in the upper part of the interosseous
membrane. In this part of its course it lies close to the
inner side of the neck of the fibula, and appears in the
present dissection immediately below the outer tuberosity of
the tibia. On the front of the leg it takes a straight course
downwards to the ankle-joint. Here it reaches the dorsum of
the foot, and receives the name of dot sa/is pedis.
In the upper two -thirds of the leg the anterior tibial
artery is very deeply placed. It lies upon the interosseous
membrane in the interval between the tibialis anticus on the
inner side, and the extensor longus digitorum and the
extensor longus hallucis on the outer side. In the lower
third of the leg where the muscles give place to their tendons
the artery comes nearer to the surface. In this part of its
course it rests upon the tibia and is overlapped on the outer
side by the extensor longus hallucis. Immediately above
the ankle-joint the tendon of that muscle crosses the artery
and comes to lie on its inner side.
Two vence, comites closely accompany the anterior tibial
artery, and send short communicating branches both in front
of it and behind it. The a?iterior tibial nerve is also intimately
related to it. It joins the artery a short distance below the
knee and soon takes up a position in front of the vessel.
Near the ankle-joint the nerve as a rule assumes a place on
the outer side of the artery.
On the front of the leg the anterior tibial artery gives off
the following branches : —
1. Muscular.
2. Anterior recurrent tibial.
3. External malleolar.
4. Internal malleolar.
The muscular branches are numerous and come off at
irregular points along the whole length of the artery. They
supply the muscles on the front of the leg.
Anterior Recurrent Tibial Artery (arteria recurrens tibialis
anterior). — This, small vessel springs from the anterior tibial
immediately after it reaches the front of the leg. It turns
upwards on the external tuberosity of the tibia in the fibres of
the tibialis anticus muscle. Its terminal twigs reach the front
of the knee-joint, and anastomose with the inferior articular
branches from the popliteal artery.
Malleolar Arteries. — These arteries take origin immediately
252
THE LOWER LIMB
above the ankle-joint. The external malleolar (arteria malleolaris
anterior lateralis) is the larger of the two, and passes outwards
under cover of the tendons of the extensor longus digitorum
and peroneus tertius, to reach the outer surface of the
external malleolus. It
anastomoses with the
anterior peroneal and
tarsal arteries. The
internal malleolar (ar-
teria malleolaris an-
terior medialis) runs
inwards under cover
of the tendons of the
Sr Tibia
Tibialis anticus
- Extensor longus digitorum
- Peroneus brevis
Peroneus longus
- Extensor longus hallucis
extensor longus hal-
lucis and tibialis anti-
cus. It inosculates
with branches from
the posterior tibial
artery.
Arteria Dorsalis
Pedis. — The dorsal
artery of the foot is
the continuation of
the anterior tibial.
It begins in front of
the ankle-joint at a
point midway be-
tween the two mal-
leoli, and it extends
forwards upon the
forepart of the astra-
galus, the scaphoid,
and the middle cunei-
form bones to the
posterior part of the
Fig. 91.— Dissection of the Dorsum of the Foot, interosseous space be-
tween the metatarsal
bones of the great toe and the second toe. Here it leaves
the dorsum of the foot by dipping downwards between the two
heads of the first dorsal interosseous muscle to reach the sole
and unite with the external plantar artery in the formation of
the plantar arch. Its relations on the dorsum of the foot are
Peroneus tertius
Fibula
Anterior annular ligament
Extensor longus hallucis
Dorsalis pedis artery
Anterior annular ligament
Anterior tibial nerve
Tibialis anticus
Nerve to extensor
)revis hallucis
Extensor longus
igitorum
eroneus tertius
Extensor brevis
itorum
Metacarpal artery
Tendons of extensor
ongus digitorum
THE LEG
53
very simple, (i) It lies in the interval between the tendon
of the extensor longus hallucis on the inner side and the
innermost tendon of the extensor longus digitorum on the
outer side. (2) At its commencement it is crossed by the
lower part of the anterior annular ligament, whilst near its
termination it is crossed by the innermost tendon of the
extensor brevis digitorum ; with these exceptions the vessel
is simply covered by the integument and fascia. (3) The
External branch of
anterior tibial nerve
Anterior tibial nerve
Dorsalis pedis artery
Extensor longus hallucis
Metatarsal artery
Tendon of peroneus longus
in the sole of the foot
Plantar arch
Adductor obliquus hallucis I
Anterior tibial nerve
Extensor brevis
digitorum
Peroneus tertius
Deep branch of external
plantar nerve
External plantar artery
Adductor transversus
hallucis
FlG. 92. — Dissection of the Dorsum of the Foot. The 2nd, 3rd, and 4th
Metatarsal Bones have been removed to show the Plantar Arterial Arch
in the sole of the foot.
internal terminal branch of the anterior tibial nerve lies along
its outer side, and two vena comites accompany it.
As the dorsalis pedis artery traverses the dorsum of the
foot it gives off several twigs to the inner margin of the foot,
and also three named branches : —
1. The tarsal.
2. The metatarsal.
3. The first dorsal interosseous.
254 THE LOWER LIMB
Tarsal and Metatarsal Arteries. — The tarsal artery arises
opposite the scaphoid bone, and the metatarsal artery near the
bases of the metatarsal bones. They both run outwards
under cover of the extensor brevis digitorum to reach the
outer margin of the foot. There they anastomose with
branches of the external plantar artery. The tarsal artery
also anastomoses with the external malleolar and peroneal
arteries.
From the arch which is formed by the metatarsal artery
three dorsal interosseous arteries proceed, one to each of the
three outer interosseous spaces. At the clefts between the
toes these divide and supply dorsal digital twigs to the
adjacent sides of the second, third, fourth, and fifth toes.
From the outermost interosseous artery a twig is also given
to the outer side of the little toe.
First Dorsal Interosseous Artery. — This small vessel takes
origin from the dorsalis pedis at the point where it turns down-
wards to reach the sole of the foot. It continues forwards
upon the first dorsal interosseous muscle, and divides into
dorsal digital branches for the inner side of the great toe and
the adjacent sides of the great toe and second toe.
Anterior Peroneal Artery- — This is one of the two
terminal branches of the peroneal branch of the posterior
tibial. It reaches the front of the leg by piercing the inter-
osseous membrane about one and a half or two inches above
the outer malleolus, and it descends upon the lower part of
the fibula under cover of the peroneus tertius. It is dis-
tributed on the outer side of the tarsus, where it anastomoses
with the external malleolar and the tarsal arteries.
Extensor Brevis Digitorum. — The extensor brevis digitorum
may now be examined. It arises from the anterior part of the
os calcis, and also from the lower part of the anterior annular
ligament. It splits into four fleshy bellies, which extend
forwards and inwards on the dorsum of the foot, and end in
four slender tendons, for the four inner toes. The innermost
tendo?i crosses the dorsalis pedis artery near its termination,
and is inserted into the dorsal aspect of the base of the first
phalanx of the great toe ; the remaining three tendons join
the long extensor tendons which go to the second, third, and
fourth toes. The extensor brevis digitorum is supplied by the
external branch of the a?iterior tibial nerve.
Anterior Tibial Nerve (nervus peroneus profundus).- — The
THE LEG
255
anterior tibial nerve is one of the terminal branches of the
external popliteal. It arises on the outer side of the neck of
the fibula, and, piercing the upper part of the extensor longus
digitorum obliquely, joins the anterior tibial vessels a short
distance below the external tuberosity of the tibia. These it
accompanies for the remainder of its course. In the first
instance it is placed in front of them, but near the ankle-
Extensor longus hallucis
Anterior tibial vessels
and
Extensor long
digitoru
Peroneus tertius
Fibula
Interosseous
calcaneo-
astragaloid lig.
Os calcis
Peroneus brevis
External annular
1
Anterior annular lig.
Tibialis amicus
Tibia
Astragalus
/olL T... ,.
£@v-:-/ '&*%&'+?£&*.$ ■ . (y l ! Tibialis
f J
\'~ \.''y 'i^t\^<' "'.■''..' ' j^>^ "''
ligament
Peroneus longus
Abductor
minimi digiti
Plantar fascia
posticus
1 annular lig.
Flexor longus
digitorum
'>*vpy —/ji _ internal plantar artery
_ "' ~^y/ I Internal plantar nerve
Flexor longus hallucis
■ \<C:'\ lOH^N/ ^Extern
ctor hallucis
ternal plantar nerve
External plantar artery
Flexor brevis digitorum
Accessorius
Fig. 93. — Coronal section through the Left Ankle-joint, Astragalus,
and Calcaneum (Patersorii.
joint it lies on their outer side. Passing behind the anterior
annular ligament, it ends by dividing into an internal and an
external branch.
In its course through the leg the anterior tibial nerve gives
muscular bra?iches to the extensor longus digitorum, tibialis
anticus, the extensor longus hallucis, and the peroneus tertius ;
likewise a fine articular hvig to the ankle-joint.
The i?iternal terminal bra?ich of the anterior tibial nerve is
continued forwards upon the dorsum of the foot along the
outer side of the dorsalis pedis artery. Reaching the first
256 THE LOWER LIMB
interosseous space it pierces the deep fascia, and divides
to supply the contiguous margins of the great toe and the
second toe (p. 245). Before it reaches the surface, it furnishes
articular twigs to the tarso-metatarsal and metatarso-phalangeal
joints of the great toe, and frequently also a fine muscular twig
to the dorsal surface of the first dorsal interosseous muscle.
The external ter??iinal branch of the anterior tibial nerve
turns abruptly outwards under cover of the extensor brevis
digitorum, and ends on the dorsum of the foot in a gangliform
enlargement. From this branches proceed for the supply of
the extensor brevis digitorum, and the numerous articulations
in the neighbourhood. One fine filament can, in most cases,
be traced to the second dorsal interosseous muscle. The
terminal swelling resembles closely the corresponding enlarge-
ment in which the posterior interosseous nerve of the upper
limb ends.
Anterior Annular Ligament. — The dissector should again
examine this ligament, and the arrangement of the structures
which pass under it. The upper portion is attached to the
fibula by its outer end, and to the tibia by its inner extremity.
By dividing its fibular attachment, and throwing it inwards,
it will be seen to give a separate and distinct sheath to the
tibialis anticus.
The lower portion is the more important of the two. Its
attachments have already been noted (p. 245). Examine the
manner in which it holds the tendons in position. It
consists of two layers, and these, by separating at certain
points and becoming re-united at others, form three distinct
compartments. Through the innermost passes the tendon of
the tibialis anticus ; through the middle one passes the tendon
of the extensor longus hallucis ; and through the outermost are
transmitted the tendons of the extensor longus digitorum and
peroneus tertius. On opening up these sheaths each will be
seen to be lined by a synovial membrane. Lastly, note the
position of the anterior tibial vessels and nerve as they pass
under cover of the ligament. They lie between the extensor
longus hallucis and the extensor longus digitorum (Fig. 93).
Peroneal Region.
The peroneal or outer compartment of the leg should now be opened by
dividing, in a longitudinal direction, the fascia which covers it. Enclosed
within it are : —
THE LEG 257
1. The peroneus longus.
2. The peroneus brevis.
3. The termination of the external popliteal nerve.
4. The musculo-cutaneous nerve.
Peroneus Longus. — The peroneus longus muscle arises from
the head and from the outer surface of the shaft of the fibula
in its upper two-thirds. A surface of origin is also afforded to
it by the fascia which covers it, and by the two peroneal inter-
muscular septa. It ends a short distance above the ankle in a
long tendon, which is continued downwards behind the external
malleolus. Gaining the outer margin of the foot, it proceeds
forwards on the outer surface of the os calcis to the groove on
the under surface of the cuboid, which conducts it transversely
into the sole. Its insertion will be examined at a later period.
It is supplied by the musculo-cutaneous nerve.
Peroneus Brevis. — This muscle arises from the lower two-
thirds of the outer surface of the shaft of the fibula, below and
in front of the peroneus longus, and from the peroneal inter-
muscular septum on either side of it. Its tendon descends
behind the external malleolus, and then turns forwards on the
outer surface of the os calcis to gain an insertion into the
projecting base of the metatarsal bone of the little toe.1 On
the back of the external malleolus the tendon of the peroneus
brevis lies directly under cover of the tendon of the peroneus
longus, and therefore in contact with the bone. On the outer
surface of the os calcis the tendon of the peroneus brevis is
placed at a higher level than that of its fellow muscle.
As the tendons of the two peronei muscles proceed down-
wards in the hollow between the external malleolus and the
posterior prominence of the os calcis they are held in place by
the external annular ligament, and their movements are facilitated
by the presence of a common synovial sheath. On the outer
surface of the os calcis each tendon is retained in position by
a separate fibrous sheath, into which the common synovial
membrane is prolonged. The peroneal tubercle of the os
calcis intervenes between these two sheaths. The peroneus
brevis is supplied by the musculo-cutaneous nerve.
External Popliteal Nerve (nervus peronaeus communis). —
This nerve has previously been traced as far as the neck of
1 A small tendinous slip will, as a general rule, be observed to proceed
forwards from the tendon of the peroneus brevis to join the tendon of the long
extensor on the dorsum of the little toe. This is the peroneus quinti digiti.
VOL. I — 17
25 8 THE LOWER LIMB
the fibula. At this point it disappears from view by passing
forwards between the peroneus longus muscle and the bone.
The muscle must therefore be carefully turned aside from its
origin in order that the nerve may be followed out. It will
be found to give off a small ?-ecurrent articular nerve to the
knee -joint, and then to divide into the anterior tibial and
?nusculo-cutaneous nerves.
The recurrent branch accompanies the anterior recurrent
tibial artery. It turns upwards in the fibres of the tibialis
anticus. To the upper part of this muscle it gives several
twigs, whilst its terminal filaments gain the front of the
knee-joint.
The anterior tibial nerve pierces the upper part of the
extensor longus digitorum to reach the front of the leg, where
-it has already been dissected.
Musculo-cutaneous Nerve (nervus peronseus superficialis).
— This nerve proceeds downwards in the substance of the
peroneus longus. It reaches the interval between- the two
peronei muscles, gives branches to both, and lastly comes to lie
between the peroneus brevis and the extensor longus digitorum.
In the lower third of the leg it pierces the fascia, and becomes
cutaneous.
Tibial Region.
This region corresponds to the subcutaneous or inner
surface of the tibia. The deep fascia blends with the peri-
osteum of the bone, and the only structures which have to
be examined are : —
i. The internal saphenous vein.
2. The internal saphenous nerve.
3. The expanded tendons of insertion of the sartorius,
semitendinosus, and gracilis.
4. Internal lateral ligament of the knee-joint.
5. Inferior internal articular artery and nerve.
The internal saphe?ious nerve and vein, as they pass from
the anterior to the posterior tibio-fibular region, cross obliquely
over the lower third of the inner surface of the tibia.
The insertion of the sartorius, gracilis, and semitendinosus
into the upper part of the inner surface of the tibia should
again be examined. Observe how the sartorius overlaps the
tendons of the other two, and how the tendon of the gracilis
THE LEG 259
overlaps the upper part of the tendon of the semitendinosus.
A synovial bursa separates these tendons from each other.
The internal lateral ligament of the knee-joint will be seen
extending downwards for a short distance upon the inner
aspect of the shaft of the tibia. Passing forwards under cover
of this ligament, so as to gain the anterior aspect of the
knee, are the inferior internal articular vessels and nerve.
Posterior Tibio-Fibular Region.
The following is a list of the structures which are met
with in this dissection : —
>
c r • 1 / Internal saphenous.
1. Superficial veins. . ^ . , r,
r I Fxternal saphenous.
2. Cutaneous ner
3. Deep fascia.
f Gastrocnemius.
4. Superficial muscles of the calf. - Plantaris.
- I rUS.
5. Tendo Achillis and its bursa.
6. Posterior tibial vessels.
7. Posterior tibial nerve.
l' Popliteus.
o t-v 1 ' Flexor loneus hallucis.
8. Deep muscles, - ~u- ,• & .
r ' Tibialis posticus.
\ Flexor longus digitorum.
9. Internal annular ligament.
Reflection of Skin. — The limb must now be placed on its anterior
aspect, and the muscles of the calf rendered tense by flexing the foot at the
ankle-joint. This position should be maintained by the aid of hooks,
fastened to the toes and to the under surface of the table. Incisions. — (1)
A longitudinal incision along the middle fine of the leg on its posterior
aspect to the extremity of the heel. (2) A transverse incision at the lower
end of this, extending along the inner and outer margins of the foot for
about two inches on either side.
The two flaps of skin thus marked out must be raised and turned
outwards and inwards.
Superficial Veins. — The internal and external saphenous
veins must be traced in the substance of the fatty superficial
fascia. Both of these vessels have been seen in previous
steps of the dissection. The internal saphenous vein has been
observed to arise from the inner extremity of the venous arch
on the dorsum of the foot, and it has been followed upwards
for a short distance in front of the inner malleolus, and then
upon the inner aspect of the lower part of the tibia. It has
also been dissected upon the inner aspect of the thigh and
260
THE LOWER LIMB
knee. It can now be exposed in its course along the inner
side of the calf of the leg.
It lies a short distance
behind the internal border
of the tibia. The external
saphenous vein has been seen
to arise from the outer end
of the dorsal arch and to
pass upwards behind the
outer malleolus. It may
now be followed as it
ascends along the outer
side of the tendo Achillis
to the back of the leg,
where it lies over the
interval between the two
heads of the gastrocnemius
muscle. When it gains the
lower part of the popliteal
space it pierces the deep
fascia and joins the pop-
liteal vein.
Associated with each
of these veins are certain
cutaneous nerves, which
must be displayed at the
same time. The small
sciatic is closely related to
the external saphenous
vein in its upper part, and
the external saphenous nerve
accompanies it in the lower
half of the leg. In com-
pany with the internal saph-
enous vein we find the inter-
nal or long saphenous nerve.
Cutaneous Nerves. —
These are very numerous.
On the inner side of the
leg are — ( i ) the i?iternal or
the posterior branch of the internal
Lumbar nerves
Iliac branches of last
dorsal and ilio-hypo--
gastric
Sacral nerves
Perforating
cutaneous
Branches from
small sciatic
External cutaneous
Long pudendal
Small sciatic
Internal cutaneous
External cutaneous
Internal cutaneous
Nervus communicans
fibularis
Small sciatic
Nervus communicans
tibialis
External saphenous
Internal calcaneal!
FlG. 94.- — Cutaneous Nerves on
the posterior aspect of the Lower Limb
long saphenous; (2)
cutaneous ; and (3) the internal calcanean
THE LEG 261
The guide to the internal saphenous nerve is the vein of the
same name. It may now be exposed in its entire course
along the inner side of the leg (Fig. 70, p. 198). The
posterior branch of the internal cutaneous proceeds downwards
a short distance behind the preceding nerve. It usually ends
about the middle of the leg. The internal calcanean is a
branch of the posterior tibial nerve. Dissect for it in the
interval between the prominence of the heel and internal
malleolus. It pierces the internal annular ligament nearer the
former than the latter. Its branches of distribution to the
skin of the heel and sole will be seen in a future dissection.
In the middle line of the leg two nerves will be found, viz.
— (1) the small sciatic, and (2) the nervus communicans tibialis.
They have both been previously seen in the dissection of the
popliteal space. The nervus communicans tibialis, a branch of
the internal popliteal, descends in the interval between the
two heads of the gastrocnemius and pierces the deep fascia
midway between the knee and ankle. A short distance
below this it is joined by the nervus communicans fibularis,
and then acquires the name of external saphenous.
On the outer side of the posterior aspect of the leg is the
nervus communicans fibularis, a branch of the external popliteal.
It descends upon the outer head of the gastrocnemius, and,
perforating the deep fascia, unites with the nervus communi-
cans tibialis a short distance below the middle of the leg, to
form the external saphenous nerve. The latter has already
been traced behind the external malleolus to the outer margin
of the foot and little toe.
Deep Fascia. — A continuous view of the deep fascia on the
back of the leg can now be obtained by removing the remains
of the superficial fat. Observe how thin and transparent it
is in the upper part of the leg, and how it thickens as it is
followed downwards towards the heel. At no point, however,
is it very dense. As it passes over the interval between the
heel and the internal malleolus it forms the internal annular
ligament. It is continuous above with the popliteal fascia, and
a short distance below the knee, on the inner side, it receives
a reinforcement of fibres from the tendons of the sartorius, the
gracilis, and the semitendinosus.
Osteofascial Compartments 011 the back of the leg. — Divide the fascia
along the middle line and turn it outwards and inwards. Leave the internal
annular ligament intact. On raising the inner part of the fascia it will be
262
THE LOWER LIMB
seen to be attached to the internal border of the tibia. In fact, it blends
with the periosteum covering the inner subcutaneous surface of this bone.
On turning the outer portion of fascia outwards it will be observed to be
directly continuous with the fascia on the front of the leg : further, the
strong intermuscular septum (posterior peroneal septum) which passes in to
join the external border of the fibula between the peroneal muscles and the
muscles on the posterior aspect of the leg will be demonstrated. In this
manner, then, the large posterior osteo-fascial compartment is formed, and,
as the dissection goes on, two partitions will be noticed to stretch across it
so as to subdivide it into three portions. The most superficial of these holds
the superficial muscles of the calf ; the intermediate portion contains the
flexor muscles with the posterior tibial vessels and nerve : whilst the deepest
part encloses the tibialis posticus muscle (Fig. 88, p. 246).
One of these partitions may be exposed at the present moment by
removing the fat which is usually accumulated under cover of the tendo
Achillis. Subjacent to this tendon
is the layer of fascia in question.
It stretches between the tibia and
fibula, and separates the superficial
from the deep group of muscles. In
this locality it will be seen to be very
dense, and to be strengthened by
numerous transverse fibres. It be-
comes continuous on the inner side
of the ankle with the internal annular
ligament — indeed, the dissector will
not fail to observe that it takes a
more prominent part in the forma-
tion of this ligament than the invest-
ing aponeurosis of the limb. In the
upper part of the leg it becomes
very thin.
Posterior crucial Anterior cruci,
ligament ligament
Adductor
magnus
Fig. 95. — Posterior aspect of lower
portion of Femur with Attachments of
Muscles mapped out.
Superficial Muscles. — The
superficial muscles of the calf
of the leg are three in number,
viz., the gastrocnemius, the
plantaris, and the soleus. The gastrocnemius is the most
superficial ; the soleus is placed under cover of the gastro-
cnemius ; whilst the slender plantaris extends downwards and
inwards between them. The tendons of insertion of the
gastrocnemius and soleus unite to form the tendo Achillis.
Gastrocnemius. — This strong muscle arises by two heads
from the posterior aspect of the lower end of the femur. These
heads have been already studied in connection with the pop-
liteal space, which they bound in its lower part. The outer
head springs from an impression on the outer surface of the
external condyle of the femur, and also from a small portion
of the posterior surface of the bone immediately above the
condyle. The iimer head takes origin from the upper 'part of
THE LEG 263
the internal condyle, and likewise from the inferior portion
of the internal supracondyloid ridge of the femur. The two
fleshy bellies swell out as they descend, and end near the
middle of the leg in a thin aponeurotic tendon. They
do not blend with each other. They are usually separated by
a furrow, at the bottom of which the flattened tendon,
to which the fasciculi of both heads are attached, may be
seen. The internal head is the more bulky of the two, and
it extends lower down than the external head. The flattened
tendon in which they terminate narrows slightly as it descends,
and a short distance below the middle of the leg it blends
with the stouter tendon of the soleus to form the tendo
Achillis.
The gastrocnemius is supplied by the internal popliteal
nerve.
Dissection. — The aponeurotic tendon of the gastrocnemius may be
divided in the middle of the leg, and the two heads of origin thrown
upwards towards the back of the femur. The sural arteries from the
popliteal trunk, and the branches of supply from the internal popliteal
nerve which enter the heads of the gastrocnemius, can thus be preserved.
On raising the upper portion of the inner head, a bursa which intervenes
between it and the condyle of the femur will be brought into view. On
opening this with the knife it will, in all probability, be found to com-
municate with the interior of the knee-joint. The smooth and tendinous
opposed surfaces of the gastrocnemius and the soleus, and the narrow tendon
of the plantaris, which passes downwards and inwards between them, are
now displayed.
Plantaris. — The small fleshy belly of the plantaris is not
more than three or four inches long. It lies along the inner
side, and partly under cover of the outer head of the gastro-
cnemius, and it arises from the posterior surface of the femur
immediately above its external condyle. It ends in a slender
tendon which is remarkable for its great length. This pro-
ceeds downwards and inwards between the gastrocnemius
and soleus, and then runs along the inner side of the tendo
Achillis to gain insertion into the posterior aspect of the os
calcis. It is frequently closely connected with the tendo
Achillis, and sometimes becomes blended with it or with the
fascia of the leg before it reaches the os calcis.
The plantaris is supplied by a branch from the internal
popliteal nerve.
Dissection. — The plantaris may now be reflected.
Soleus. — This is a flat, thick, and powerful muscle which
264 THE LOWER LIMB
arises from both bones of the leg, as well as from a strong
fibrous arch which is thrown across the posterior tibial
vessels. Its fibular origin is from the posterior surface of the
head and the upper third of the posterior surface of the
shaft of the bone ; by its tibial origin it is attached to the
oblique line of the tibia below the popliteal surface, and to
the internal border of the bone below this as far down as
the middle of the leg (Fig. 97, p. 268). The soleus ends in
a strong stout tendon which joins with the tendon of the
gastrocnemius to form the tendo Achillis. Branches from
the ijiternal popliteal nerve supply the soleus.
Tendo Achillis (tendo calcaneus). — This is the most powerful
tendon in the body. It narrows as it descends, but near the
heel it again expands slightly. It is inserted into the middle
portion of the posterior surface of the os calcis. The fleshy
fibres of the soleus are continued downwards on its deep
surface to within a short distance of the heel. A synovial
bursa intervenes between the tendo Achillis and the upper
part of the posterior surface of the os calcis.
Dissection. — Divide the soleus muscle transversely at the level at which
it is joined by the gastrocnemius tendon, and turn downwards the tendo
Achillis. Next make a vertical incision through the substance of the soleus
in the middle line, so as to divide it into two lateral portions. By this
dissection the tendinous arch which is thrown across the blood-vessels is
exposed in the upper part, and both the tibial and fibular origins with the
blood-vessels and nerves which enter them are preserved. The two portions
of the fleshy belly of the muscle may now be turned outwards and inwards,
and the branches which the muscle receives from the peroneal and posterior
tibial arteries may be cleaned.
The deep fascial septum which stretches across from the tibia to the
fibula between the superficial and deep muscles on the back of the leg may
now be removed. In doing this note the manner in which it becomes
continuous below with the internal annular ligament. On no account
interfere with this ligament. The posterior tibial vessels and nerve, with
their branches, should be dissected with as little disturbance to the deep
muscles as possible. The muscle which lies on the fibula is the flexor longus
hallucis ; the muscle on the tibia is the flexor longus digitorum ; whilst the
third muscle between and on a deeper plane than the other two is the
tibialis posticus.
Termination of the Popliteal Artery. — The termination of
the popliteal artery lies under cover of the upper border of
the soleus. It should now be cleaned, and it will be seen to
end at the lower margin of the popliteus muscle by dividing
into the a?iterior and posterior tibial arteries. Further, the
venae comites which accompany these vessels will be observed
to join at this point to form the large popliteal vein.
THE LEG 265
Anterior Tibial Artery (arteria tibialis anterior). — The
anterior tibial artery passes forwards between the two
heads of the tibialis posticus muscle to the front of the
leg, where it has already been dissected. In this part of
its course the anterior tibial artery gives off the posterior
recurrent tibial and the superior fibular branch. The
posterior recurrent tibial is a small twig which is not always
present. It runs upwards under cover of the popliteus
muscle to the back of the knee-joint. The superior fibular
runs outwards on the neck of the fibula, and is distributed to
the muscles and integument in the neighbourhood.
Posterior Tibial Artery (arteria tibialis posterior). — The
posterior tibial artery is the larger of the two terminal branches
of the popliteal trunk. It takes origin at the lower border of
the popliteus muscle and ends in the hollow on the inner side
of the os calcis, under cover of the abductor hallucis, and at
the level of the lower border of the internal annular ligament,
by dividing into the external and internal plantar arteries. In
the first instance the artery is placed between the two bones of
the leg upon the tibialis posticus muscle ; but as it descends it
inclines gradually inwards, and at its termination it lies mid-
way between the prominence of the os calcis and the internal
malleolus.
In its upper two-thirds the posterior tibial artery is situated
very deeply, being covered by the superficial muscles of the
calf. In the lower third of the leg it appears between the
tendo Achillis and the inner border of the tibia, and is merely
covered by the integument, two layers of fascia, and lower
down by the internal annular ligament. From above down-
wards it rests upon the tibialis posticus, the flexor longus digi-
torum, the tibia, and the posterior aspect of the ankle-joint.
Throughout its entire course the posterior tibial artery is
closely accompanied by two vence comites. The posterior
tibial 7ierve is at first on its inner side, but it soon crosses the
vessel, and then proceeds down on its outer side.
The following are the branches which issue from the
posterior tibial artery : —
1. Muscular.
2. Nutrient.
3. Peroneal.
4. Cutaneous.
5. Internal calcanean.
6. Communicating.
The muscular branches supply the deep muscles on the
back of the leg, and one or two of large size enter the soleus.
266
THE LOWER LIMB
The cutaneous branches are given to the skin on the inner
aspect of the leg.
Internal popliteal nerve
-External popliteal nerve
Popliteal artery
Jgj'lf — Semimembranosus
Outer head of gastrocnemius
Plantaris •
Inner head of gastrocnemius
)
Tendon of semimembranosus
^Internal inferior articular artery
External inferior articular artery
Popliteal vessels
Popliteus muscle
Xerve to popliteus
External popliteal nerve
Termination of popliteal artery
Soleus (cut)
Tibia
Fibula
Posterior tibial vessels and nerve
Peroneal vessels
Nutrient artery to fibula
Peroneus longus
Flexor longus hallucis
ibialis posticus
Flexor longus digitorum
Posterior tibial nerve
Posterior tibial vessels
Flexor longus hallucis
^Flexor longus digitorum
Tibialis posticus
—Tubercle on back of astragalus
Bursa
Internal annular ligament
Tendo Achillis
pIG. 96. — Deep Dissection of the Back of the Leg.
The nutrient artery (arteria nutritia tibiae) springs from the
THE LEG 267
posterior tibial close to its origin, and after giving some
twigs to muscles enters the nutrient foramen of the tibia.
It is remarkable on account of its large size.
The communicating bra?ich (ramus communicans) is given
off about an inch above the lower end of the tibia. It
passes transversely outwards under cover of the flexor longus
hallucis, and joins the peroneal artery.
The internal calcanean branch (rami calcanei mediales)
pierces the internal annular ligament, and accompanies the
nerve of the same name to the skin of the heel and the
sole.
The peroneal artery (arteria peronaea) is a large branch
which proceeds from the posterior tibial about one inch or so
below its origin. In the present stage of the dissection it is
seen running obliquely downwards and outwards upon the
tibialis posticus to reach the fibula. It is. covered by the
soleus, and is accompanied by the nerve to the flexor longus
hallucis. It cannot be traced further at present, as it sinks
into the substance of that muscle.
Posterior Tibial Nerve (nervus tibialis). — This is the con-
tinuation into the back of the leg of the internal popliteal
nerve. It begins at the lower border of the popliteus muscle
and ends in the hollow between the heel and the internal
malleolus by dividing into the external and internal plantar
nerves. It accompanies the posterior tibial vessels, and pre-
sents the same relations. For a short distance in the upper
part of the leg it lies on the inner side of the posterior tibial
artery, but it soon crosses it, and is then continued down-
wards for the remainder of its course on the outer side of the
vessel.
It supplies — (a) ?nuscular branches to the tibialis posticus,
flexor longus hallucis, and flexor longus digitorum ; (p) a
cutaneous twig, the internal calcanean, which springs from it
close to its termination, and pierces the internal annular liga-
ment to reach the integument of the heel and sole of the
foot ; and (c) articular filaments to the ankle-joint.
Deep Muscles. — The popliteus muscle will be seen lying
upon the posterior aspect of the knee-joint and upon the
posterior surface of the tibia above the oblique line. Its
tendon of origin lies within the capsule of the knee-joint,
and can only be properly studied when this articulation is
dissected.
268
THE LOWER LIMB
Semimembranosus
£%*
Note the strong fascia which covers
the posterior surface of the popliteus, and
trace it upwards and inwards to the inner
side of the knee. Here it will be observed
to be continuous with the tendon of the
semimembranosus, and through it, there-
fore, the semimembranosus may be re-
garded as having an insertion into the
oblique line of the tibia.
The flexor longus hallucis is
placed upon the posterior aspect
of the fibula, and its tendon will
be noticed to groove deeply the
posterior border of the astragalus
as it passes forwards to gain the
sole of the foot. The flexor
longus digitorum lies upon the tibia.
The tibialis posticus rests upon
the interosseous membrane upon a
deeperplaneand between thefieshy
bellies of the two flexors.
Aponeurosis covering the Tibi-
alis Posticus. — This constitutes
the second partition which crosses
the posterior osteo-fascial compart-
ment of the leg. It is a strong apo-
neurosis, which is attached on the
one hand to the internal border
of the fibula, and on the other to
the vertical ridge which descends
from the oblique line on the pos-
terior surface of the tibia. To
demonstrate these attachments,
the flexor muscle of the toes must
be pushed inwards and some of
its fibres divided. The flexor longus
hallucis must in like manner be
pushed outwards. The aponeu-
rosis will then be seen to serve
as a surface of origin for both
of these muscles ; and, on its
Bones of Leg with Attachments removal, it will also be observed
of Muscles mapped out. tQ give fibreg by ks deep surface
to the subjacent tibialis posticus.
rl
Tib
Flexor long
posticus
hallucis
Peroneus longus
and brevis
Fig. 97. — Posterior aspect of
THE LEG 269
Popliteus. — The popliteus muscle arises by a stout narrow
tendon, within the capsule of the knee-joint, from the front
of the popliteal groove on the outer surface of the external
condyle of the femur. The fleshy fibres are directed inwards
and downwards, and spread out to obtain insertion into the
posterior surface of the tibia above the oblique line, and also
into the aponeurosis which covers the muscle.
The nerve to the popliteus has already been seen to arise
from the internal popliteal trunk. It can now be seen hooking
round the lower margin of the muscle to reach its deep
surface.
Flexor Longus Hallucis. — The flexor longus hallucis is a
powerful muscle which arises from the posterior surface of
the fibula below the origin of the soleus, from the posterior
peroneal septum, and from the surface of the aponeurosis
covering the tibialis posticus. Its tendon occupies a deep
groove on the posterior border of the astragalus, and turns
forwards under cover of the internal annular ligament to gain
the sole of the foot. The flexor longus hallucis is supplied
by the posterior tibial nerve.
Flexor Longus Digitorum. — The flexor longus digitorum
arises from the posterior surface of the shaft of the tibia below
the popliteus, and internal to the vertical ridge, which descends
from the oblique line. It also derives fibres from the surface
of the aponeurosis which covers the tibialis posticus. Cross-
ing the lower part of the tibialis posticus, its tendon grooves
the back of the internal malleolus on the outer side of the
tendon of that muscle. It is continued under cover of the
internal annular ligament into the sole of the foot. The
flexor longus digitorum is supplied by the posterior tibial nerve.
Tibialis Posticus. — This muscle takes origin from the pos-
terior surface of the interosseous membrane, from the posterior
part of the inner surface of the shaft of the fibula, from the
posterior surface of the shaft of the tibia on the outer side of
the flexor longus digitorum, and from the aponeurosis which
covers it. In Fig. 88, p. 246, the compartment which it
occupies is shown in a diagrammatic manner, and the surfaces
from which it takes origin are indicated. Towards the lower
part of the leg the tibialis posticus inclines inwards under cover
of the flexor longus digitorum, and its strong flattened tendon
grooves the back of the internal malleolus to the inner side
of the tendon of that muscle. Proceeding under cover of
270
THE LOWER LIMB
the internal annular ligament, its tendon is inserted into the
tubercle of the scaphoid, and also by a number of slips into
certain of the tarsal and metatarsal bones. These will be
dissected later on. The tibialis posticus is supplied by the
posterior tibial nerve.
Peroneal Artery (arteria peronea).— This vessel may now
be traced downwards as it runs along the fibula under cover
of the flexor longus hallucis. It is accompanied by two vena,
comites. About an inch or an inch and a half above the
Tibialis posticus _
Flexor longus digitorunu
Posterior tibial /
artery and nerve I
Flexor longus hallucis .
Tibialis posticus
Internal plantar nervess
Flexor longus digitorum
External plantar artery J
and nerve I
Internal plantar artery
Abductor hallucis ^if\^
Fig.
Nerve to the accessorius Internal calcanean
Abductor minimi digiti vessels and nerve
Accessorius
. — Dissection of the Inner Ankle.
ankle-joint it ends by dividing into its two terminal branches
— the anterior and the posterior peroneal arteries.
In addition to these it gives off —
1. Muscular branches.
2. The nutrient artery to the fibula.
3. ' The communicating artery.
The muscular branches supply the muscles around it. The
nutrient artery (arteria nutritia fibulae) enters the nutrient
foramen on the posterior surface of the fibula. The com-
municating artery (ramus communicans) arises a short distance
above the ankle-joint, and runs transversely inwards under
cover of the flexor longus hallucis to join the posterior tibial
artery.
THE LEG 271
The anterior peroneal artery (ramus perforans) passes
forwards through the interosseous membrane, and has already
been dissected on the front of the leg.
The posterior peroneal artery is continued downwards behind
the external malleolus, and ends on the outer surface of the
os calcis, where it anastomoses with the external malleolar,
tarsal, and anterior peroneal vessels.
Internal Annular Ligament. — The connections of this
thickened band of deep fascia should be carefully studied,
and also the arrangement of the structures which pass under
cover of it into the sole of the foot. It bridges across the
hollow between the prominence of the os calcis and the
internal malleolus, and it is attached to both. Above, it is
chiefly connected with that layer of the deep fascia which
intervenes between the superficial and deep muscles on the
back of the leg, but it is also continuous with the general
aponeurotic investment of the limb. Inferiorly, its lower
margin gives origin to the abductor hallucis, and is con-
nected with the inner portion of the plantar fascia.
Passing under cover of this ligament the dissector will
observe — (a) the posterior tibial vessels and nerve ; (b) to the
outer side of these, the tendon of the flexor longus hallucis ;
(c) to their inner side, the tendons of the flexor longus digi-
torum and tibialis posticus. From within outwards these
structures lie in the following order : —
1. Tendon of tibialis posticus.
2. Tendon of flexor longus digitorum.
3. Posterior tibial vessels.
4. Posterior tibial nerve.
5. Tendon of flexor longus hallucis.
The tendons are isolated from each other and from the
vessels and nerve by septa, which pass from the deep surface
of the ligament to ridges on the bones. These septa can be
demonstrated by slitting up the ligament, for a short dis-
tance, in the line of each of the tendons : each of the three
sheaths will then be seen to be lined by a glistening synovial
membrane.
Anastomosis around the Ankle-joint. — The dissector
should next satisfy himself with regard to the anastomosis of
arteries which takes place around the ankle-joint. On the
outer aspect of the joint he will observe inosculations taking
place between branches of the following arteries : — (a) external
272 THE LOWER LIMB
malleolar ; (b) anterior peroneal ; (c) posterior peroneal ; and
(d) tarsal.
On the inner aspect of the joint the internal malleolar
branch of the anterior tibial anastomoses with small twigs
from the internal calcanean branch of the posterior tibial.
SOLE OF THE FOOT.
In this dissection the dissector will meet with the follow-
ing structures : —
i. Superficial fascia and cutaneous vessels and nerves.
2. Deep plantar fascia.
( Abductor hallucis.
3. Superficial muscles, \ Flexor brevis digitorum.
\ Abductor minimi digiti.
4. External and internal plantar vessels.
5. External and internal plantar nerves.
6. Tendons of flexor longus hallucis and flexor longus digitorum.
7. Musculus accessorius and lumbrical muscles.
8. Flexor brevis hallucis, adductor obliquus hallucis, and adductor
transversus hallucis.
9. Flexor brevis minimi digiti.
10. Plantar arterial arch.
11. Arteria magna hallucis.
12. Tendons of peroneus longus and tibialis posticus.
13. Interosseous muscles.
Reflection of Skin. — The limb should be placed upon the table, with
the sole of the foot facing the dissector, and the ankle supported by a good -
sized block. Two incisions are required — (1) a longitudinal incision along
the middle line of the sole, from the heel to the root of the middle toe ;
(2) a transverse cut, at the digital extremity of the mesial incision, across
the sole at the roots of the toes. The skin should also be reflected from
the plantar surface of each of the toes. This can be done by means of
a longitudinal incision along its middle line.
Superficial Fascia. — When the flaps of skin which are
mapped out by the above incisions are reflected, the peculiar
character of the thick layer of superficial fascia becomes
apparent. It is tough and granular, and in some respects
resembles the superficial fascia which covers the tuber ischii.
Traversing it are tough fibrous bands, which subdivide the
fatty tissue into small lobules, and connect the thick skin of
the sole with the plantar fascia.
Dissection.— The internal calcanean nerve, which has already been found
piercing the internal annular ligament, should be traced to its distribution.
It supplies the skin of the sole in the neighbourhood of the heel.
SOLE OF THE FOOT
273
The superficial fascia may now be removed. Divide it along the middle
line of the sole, and turn it outwards and inwards, cleaning at the same
time the deep fascia. As the dissector approaches the outer and inner
Cutaneous branche
from external plantar \
artery and nerve
Third and fourth
lumbricals
Digital nei \es fro...
external plantar^./
Os calcis
Internal calcaneal!
nerve and artery
_ Outer part of plantar
A fascia
HSSfft Cutaneous branches
from internal plantar
artery and nerve
Central part of
plantar fascia
Inner part of
plantar fascia
I digital nerves from
internal plantar
Fig. 99. — Superficial Dissection of the Sole ot the Foot ; the Skin and
Superficial Fascia alone removed,
moroins of the foot respectively, he will observe two furrows to extend
forwards on each side of the central part of the deep fascia. Along the line
of these a number of blood-vessels and some nerves will be seen piercing
VOL. 1—18
274 THE LOWER LIMB
the deep fascia in order to reach the skin. Towards the heads of the
metatarsal bones the digital vessels and nerves are unprotected by the deep
fascia, and here the dissector must proceed cautiously. The nerves and
vessels which go to the tibial side of the hallux and to the fibular side of
the little toe are especially liable to injury, as they perforate the fascia
farther back than the others. A band of transverse fibres, which crosses
the roots of the toes and lies over the digital vessels and nerves, should be
noticed. It is the superficial transverse ligament of the toes. It is closely
connected with the skin, where it forms the cutaneous webs between the
toes. By forcibly separating the toes its connections will become evident.
When the relations of this ligament have been studied it may be removed.
Plantar Fascia. — The plantar fascia, which is now.
brought into view, will be noticed to consist of three
portions — (a) a central, and (b) two lateral parts. This sub-
division is indicated by a difference in the density of the
three parts and by two shallow furrows which traverse the
foot in a longitudinal direction, one upon either side of the
strong central portion of fascia. Each of the three portions
of fascia is in relation to a subjacent muscle. The central
portion covers the flexor brevis digitorum ; the external lateral
part clothes the abductor minimi digiti ; and the internal
lateral part covers the abductor hallucis.
The central portion of the plantar fascia stands out in
marked contrast to the lateral portions in point of strength
and density. Behind, where it is attached to the internal
tuberosity of the os calcis, it is narrow, but it expands as it
passes forwards, and, near the heads of the metatarsal bones,
splits into five processes, which are bound together by trans-
verse fibres. In the intervals between the digital slips the
digital vessels and nerves and the lumbrical muscles appear.
Trace these processes forwards. One goes to the root of
each toe, and there divides into two slips, which embrace
the flexor tendons and become fixed to the flexor sheaths
and to the transverse metatarsal ligament on either side of the
toe. In its arrangement, therefore, this portion of the plantar
fascia closely resembles the central part of the palmar fascia.
The lateral parts of the plantar fascia are weak in com-
parison with the central portion. They simply constitute
aponeurotic coverings for the muscles which lie subjacent.
A strong band is to be noted in connection with the outer
part. It stretches between the prominence formed by the
base of the fifth metatarsal bone and the external tuberosity
of the os calcis.
In connection with the plantar fascia two intermuscular
SOLE OF THE FOOT 275
septa have also to be studied. These pass upwards into the
sole, along the lines of the longitudinal furrows which mark
off the central portion of the fascia from the lateral parts.
They consequently lie one upon either side of the flexor
brevis digitorum, and form partitions which separate it from
the abductor hallucis on the one side, and the abductor
minimi digiti on the other.
Dissection. — To demonstrate these septa, make a transverse incision
through the central portion of the plantar fascia about an inch in front of
the internal tuberosity of the os calcis, and also a longitudinal cut through
the same piece of fascia, extending from the first incision along the middle
line of the foot. Now raise the divided fascia and throw it outwards and
inwards. Some difficulty will be experienced in effecting this, owing to its
affording a surface of origin in its posterior part to the subjacent flexor
brevis digitorum. As we approach the margins of this muscle the septa
are brought into view.
Muscles and Tendons of the Sole. — It is customary to
look upon the muscles and tendons which we find in the
dissection of the sole as being disposed in four strata, viz. : —
( Abductor hallucis.
First layer. -' Flexor brevis digitorum.
\ Abductor minimi digiti.
1 Tendon of flexor longus digitorum.
a 1 ^ ' Musculus accessorius.
Second layer. ■ T , . , ,
J Lumbncal muscles.
^Tendon of flexor longus hallucis.
( Flexor brevis hallucis.
™. ,, ! Adductor obliquus hallucis.
1 Adductor transversus hallucis.
' Flexor brevis minimi digiti.
j Interosseous muscles.
Fourth layer. -I Tendon of the peroneus longus.
[ Tendon of the tibialis posticus.
Dissection. — The lateral portions of the plantar fascia should be raised
from the subjacent muscles. The three superficial muscles of the sole are
then exposed to view and their connections can be studied. The flexor
brevis digitorum is placed in the middle, the adductor minimi digiti
extends along the outer margin of the sole, and the abductor hallucis along
the inner margin of the sole. In the interval between the abductor
hallucis and flexor brevis digitorum the internal plantar nerve and artery
will be found. Follow the nerve toward the toes and dissect out its four
digital branches. In doing so, care must be taken of the muscular t
which are given to the flexor brevis hallucis and the innermost lumbrical
muscle. Slender branches of the internal plantar artery accompany the
digital nerves. Now trace the trunk of the internal plantar nerve back-
wards, by carefully separating the flexor brevis digitorum and the abductor
hallucis along the line of the internal intermuscular septum. It will be
found to give a branch of supply to each of these muscles. In the next
place, separate the contiguous borders of the flexor brevis digitorum and
I— 18 a
276
THE LOWER LIMB
abductor minimi digiti. The external plantar artery and nerve lie for a short
portion of their course in the interval between these muscles. Approaching
the prominent base of the fifth metatarsal bone, the artery disappears from
view by turning inwards under cover of the flexor tendons. At the same
point the external plantar nerve divides into its superficial and deep
divisions. The deep division of the external plantar nerve cannot be
dissected at present, as it accompanies the external plantar artery. The
superficial division, however, should be traced to its distribution.
Flexor brevis digitorum ~J
Abductor hallucis
Musculus accessorius
Tibialis anticu
Peroneus longu
Abductor minimi digiti
bialis posticus
exor brevis hallucis
bialis posticus
Peroneus brevis
Flex, brevis min. dig.
Adductor obliquus
hallucis
Palmar interossei
Fig. 100. — Plantar aspect of Tarsus and Metatarsus with Attachments
of Muscles mapped out.
Flexor Brevis Digitorum. — This muscle arises from the
internal tubercle of the os calcis, from the deep surface of the
central part of the plantar fascia, and from the intermuscular
septum on either side of it. About the middle of the sole
the fleshy belly divides into four slips, which end in slender
tendons for the four outer toes. These enter the fibrous flexor
sheaths of the toes, and will be afterwards studied. The
flexor brevis digitorum is supplied by the internal plantar
nerve.
SOLE OF THE FOOT 277
Abductor Hallucis. — The abductor hallucis takes origin
from the inner aspect of the internal tubercle of the os calcis,
from the internal intermuscular septum, from the lower border
of the internal annular ligament, and from the lateral part of
the plantar fascia which covers it. A strong tendon issues
from the fleshy belly. This is joined on its outer and deep
surface by fibres of the internal head of the flexor brevis
hallucis, and is inserted into the inner aspect of the base of
the proximal phalanx of the great toe. The abductor hallucis
is supplied by the internal plantar nerve.
Abductor Minimi Digiti (musculus abductor quinti digiti).
— -The origin of this muscle extends inwards under cover of
the flexor brevis digitorum. The latter muscle must there-
fore be detached from the os calcis and turned forwards.
The abductor minimi digiti is then seen to have a broad
origin from both the inner and outer tubercles of the os
calcis, from the external intermuscular septum, and the
lateral part of the plantar fascia which covers it. Its tendon
is inserted into the outer aspect of the base of the proximal
phalanx of the little toe. The abductor minimi digiti is
supplied by the external plantar nerve.
Dissection. — The origin of the abductor hallucis from the os calcis and
from the internal annular ligament should be divided and the muscle turned
inwards. With a little dissection the mode and place of origin of the
plantar arteries and nerves will be made manifest. They are the terminal
branches of the posterior tibial artery and nerve, and they arise in the hollow
of the os calcis under cover of the origin of the abductor hallucis. But
further, we are now in a position to trace the external plantar artery and
nerve as they pass outwards upon the musculus accessorius to the point
where they were first seen — viz., in the interval between the abductor
minimi digiti and the flexor brevis digitorum. In following the external
plantar nerve, the branches which it gives to the musculus accessorius and
the abductor minimi digiti must be secured. The latter nerve lies close to
the os calcis.
Internal Plantar Artery (arteria plantaris medialis). —
This is the smaller of the two terminal branches of the
posterior tibial artery. It arises in the hollow between the
internal malleolus and the prominence of the os calcis at the
lower border of the internal annular ligament. At first it is
placed under cover of the abductor hallucis, but as it pro-
ceeds forwards it appears in the interval between this muscle
and the flexor brevis digitorum. Finally, at the root of the
great toe it ends by joining the digital branch to the inner
side of the hallux.
1-I86
278 THE LOWER LIMB
The branches which proceed from the internal plantar are
small but very numerous. They are — (i) three twigs which
accompany the digital branches of the internal plantar nerve
to the clefts between the four inner toes ; these end by
joining the corresponding digital arteries; (2) a series of
cutaneous branches to the skin of the sole, which pierce the
deep fascia in the furrow between the internal lateral and
central parts of the plantar fascia; (3) a number of branches
to the muscles in the vicinity ; (4) some offsets which pass
inwards under cover of the abductor hallucis to reach the
inner border of the foot.
External Plantar Artery (arteria plantaris lateralis). — This
vessel is much larger than the internal plantar. It is accom-
panied by the external plantar nerve and two vena, comites. From
its origin in the hollow of the os calcis it proceeds outwards
across the sole to reach the interval between the flexor brevis
digitorum and the abductor minimi digiti. In this interval
it is continued forwards for a short distance, and then at the
base of the fifth metatarsal bone it turns suddenly inwards,
and crosses the sole a second time, under cover of the flexor
tendons, to form the plantar arch. In the present stage of
the dissection it is only displayed as far as the base of the
fifth metatarsal bone. Between its origin and this point its
relations are as follows: — (1) it is placed between the
abductor hallucis and the hollow of the os calcis; (2) it
lies between the flexor brevis digitorum and the musculus
accessorius ; (3) it occupies the interval between the flexor
brevis digitorum and the abductor minimi digiti. In this
latter situation it is near the surface and is merely covered by
the integument and fasciae.
The branches which proceed from this part of the vessel
are — (1) twigs to the neighbouring muscles; (2) internal
calcanean branches which arise near its origin, and gain the
heel by piercing the origin of the abductor hallucis; (3)
cutaneous branches which appear through the deep fascia
along the line of the external intermuscular septum ; (4)
twigs to the outer margin of the foot which anastomose with
the tarsal and metatarsal branches of the dorsalis pedis.
Internal Plantar Nerve (nervus plantaris medialis). — The
internal plantar nerve is the larger of the two terminal
branches of the posterior tibial, and it takes origin in the
hollow of the os calcis under cover of the internal annular
SOLE OF THE FOOT 279
ligament. It accompanies the internal plantar artery, and
presents the same relations. After it emerges from under
cover of the abductor hallucis, it gives off the digital branch
to the inner side of the hallux, and then ends in the interval
between the abductor hallucis and the flexor brevis digitorum
by dividing into three digital branches.
The branches of the internal plantar nerve are : —
1. Cutaneous twigs to the skin of the sole.
2. Muscular branches.
3. Four digital branches.
The cutaneous twigs to the integument of the sole spring
from the trunk of the nerve, and pierce the deep fascia in
the line of the internal intermuscular septum.
The four digital bra?iches supply both sides of the hallux
and of the second and third toes, and also the tibial side of
the fourth toe. The first or innermost digital nerve goes to
the inner side of the great toe. The second divides to supply
the contiguous margins of the great toe and the second toe.
The third deals similarly with the second and third toes ;
whilst the fourth supplies the adjacent sides of the third and
the fourth toes. In its digital distribution, therefore, the
internal plantar nerve closely resembles the median nerve in
the hand. To the fourth or outermost digital bra?ich a twig
of communication is given by the superficial division of the
external plantar nerve.
The digital nerves should be traced along the toes.
They are arranged in a manner very similar to that of the
corresponding nerves of the fingers.
The muscular bra?iches go to four muscles of the sole, viz.,
the abductor hallucis, the flexor brevis digitorum, the flexor
brevis hallucis, and the innermost or first lumbrical muscle.
The branches which supply the abductor hallucis and the
flexor brevis digitorum arise from the trunk of the internal
plantar nerve a short distance from its origin. The other
two spring from the inner two digital nerves : thus, from the
first digital nerve proceeds the branch to the flexor brevis
hallucis ; from the second, the branch to the first lumbrical.
External Plantar Nerve (nervus plantaris lateralis). — The
external plantar nerve corresponds to the ulnar nerve in the
palm of the hand. It accompanies the external plantar artery
and presents the same relations. In the interval between the
abductor minimi digiti and the flexor brevis digitorum, opposite
2bO
THE LOWER LIMB
the base of the fifth metatarsal bone, it divides into a deep
and a superficial part. The deep division follows the plantar
Musculus accessonus ^ Jp
Peroneus lo
Abductor minimi digiti
Flexor brevis digitorum
Twig from external
intar nerve to
musculus accessorius
\ External plantar
/ artery and nerve
\Mft ^ Internal plantar
^\ j artery and nerve
ftpr Abductor hallucis
\HI Tendon of flexor
longus digitorum
|H^ Tendon of flexor
IJI longus hallucis
Flexor brevis minimi
digiti
l.umbricals
Flexor brevis hallucis
Fig. ioi.— Dissection of the Sole of the Foot ; the Flexor Brevis Digitorum
has been reflected.
arch under cover of the flexor tendons. The superficial
division divides into two digital branches.
SOLE OF THE FOOT 281
From the trunk of the external plantar nerve proceed two
muscular branches, viz., to the musculus accessorius and to the
abductor minimi digiti.
The first or outer digital branch of the superficial part of
the external plantar nerve goes to the outer side of the little
toe. It also gives muscular twigs to the flexor brevis minimi
digiti and the interosseous muscles in the fourth intermeta-
tarsal space.
The second digital branch divides to supply the adjacent
sides of the fourth toe and little toe. It likewise sends a
twig of communication to the fourth digital branch of the
internal plantar nerve.
Dissection. — The abductor minimi digiti should be completely detached
from its origin, and turned forwards in order that a good display may be
obtained of the structures composing the second stratum of the sole.
Second Layer of Muscles and Tendons. — As the tendon
of the flexor longus hallucis enters the sole it grooves the
under surface of the sustentaculum tali and inclines inwards
towards the great toe. The tendon of the flexor longus
digitorum, on the other hand, inclines outwards to reach the
middle of the foot, where it divides into four tendons for the
four outer toes. Moreover, the tendons of these two muscles
cross each other in the sole — the tendon of the flexor
digitorum lying upon the plantar or superficial surface of the
tendon of the flexor longus hallucis, and receiving from it a
strong tendinous slip.
Sir William Turner has called attention to fhe fact that this slip, which
passes from the tendon of the flexor longus hallucis to the tendon of the
flexor longus digitorum, varies greatly in magnitude and in the manner in
which it is connected with the flexor tendons of the toes. In the majority
of cases it goes to the tendons of the second and third toes ; in some cases,
however, only to the tendon of the second toe, or to the tendons of the
second, third, and fourth toes. Very rarely does it divide so as to bring
all the tendons of the flexor longus digitorum into connection with the
tendon of the flexor longus hallucis.
The musculus accessorius, which is inserted into the tendon
of the long flexor of the toes, and also the four lumbrical
muscles which arise from the flexor tendons, can now be dis-
tinguished. Note the position of the long plantar ligament
between the two heads of origin of the accessorius.
Fibrous Flexor Sheaths. — Before tracing the flexor
tendons forwards on the toes, it is necessary to examine the
sheaths which retain them upon the plantar aspect of the
282
THE LOWER LIMB
phalanges. In their construction these fibrous sheaths are
precisely similar to the corresponding sheaths of the fingers.
They are not so strongly marked, but they present the same
thickenings over the shafts of the phalanges and the same
want of strength opposite the interphalangeal joints. They
may now be opened in order that the enclosed tendons may
be examined. A synovial sheath is present in each to
facilitate the play of the flexor
tendons within them.
Insertions of the Flexor Tendons.
— Two tendons, one from the flexor
brevis digitorum, and one from the
flexor longus digitorum, enter the
flexor sheath of each of the four
outer toes. Of these, the tendon of
the former muscle corresponds with
a tendon of the flexor sublimis in
the hand, whilst the tendon of the
flexor longus digitorum corresponds
with a tendon of the flexor pro-
fundus. Further, they are inserted
umbricai in exactly the same manner. The
uscles
tendon of the flexor brevis, which
is the more superficial, divides into
two slips, and between these the
tendon of the flexor longus proceeds
forwards to its insertion into the
plantar aspect of the base of the
ungual phalanx. The two slips of
the tendon of the flexor brevis are
i Tendon^ mrth°ef Joined b>' their margins on the deep
surface of the long flexor tendon,
and then separate again to obtain
insertion into the sides of the shaft of the second phalanx
about its middle. .
Tendon of the Flexor Longus Hallucis. — After giving its
slip to the tendon of the flexor longus digitorum, the tendon
of the flexor longus hallucis is prolonged forwards to the
great toe. On the plantar aspect of the hallux it is retained
in place by a flexor sheath, and finally it is inserted into
the base of the terminal phalanx.
Musculus Accessorius (musculus quadratus plantae). — This
Fig. i 02
Muscles and
Sole of the Foot.
SOLE OF THE FOOT 283
muscle takes a course straight forwards from the heel, and acts
as a direct flexor of the toes. It also tends to bring the
tendons of the long flexor muscle into a line with the toes
upon which they operate. It arises by two heads which
embrace the os calcis and the long plantar ligament. The
inner head, wide and fleshy, springs from the inner concave
surface of the os calcis ; the outer head, narrow, pointed, and
tendinous, takes origin from the outer surface of that bone,
and also from the long plantar ligament. The musculus
accessorius is inserted into the tendon of the flexor longus
digitorum in the middle of the sole. It is supplied by a
branch from the external plantar nerve.
Lumbrical Muscles. — The lumbrical muscles of the foot are
not so strong as the corresponding muscles in the palm of the
hand. They are four in number, and arise from the tendons
of the flexor longus digitorum. The outer three lumbricals
spring from the adjacent sides of the tendons between which
they lie ; the first or innermost muscle takes origin from the
tibial side of the tendon of the long flexor which goes to the
second toe. The slender tendons of the lumbrical muscles pro-
ceed to the tibial side of the four outer toes, and are inserted
into the expansions of the extensor tendon on the dorsal aspect
of the proximal phalanges. The first or innermost lumbrical
is supplied by the inter?ial plantar nerve : the others by the
external plantar nerve.
Dissection. — To bring the third layer of muscles into view we require to
make the following dissection : — Divide the two heads of the accessorius
and draw the muscle forwards from under the external plantar vessels and
nerve. Sever also the tendons of the flexor longus digitorum and the
flexor longus hallucis at the point where they emerge from under cover of
the internal annular ligament. Upon cutting the branch which is given
by the external plantar nerve to the accessorius these structures can be
thrown forwards towards the toes. On raising the lumbrical muscles, the
twigs which are furnished to the second, third, and fourth by the deep
division of the external plantar nerve must be looked for. That for the
second lumbrical muscle will be seen to take a recurrent course around the
adductor transversus hallucis muscle. Lastly, cut the internal plantar
nerve close to its origin and turn it aside.
Third Layer of Muscles. — The flexor brevis hallucis lies
along the outer side of the abductor hallucis.
The adductor obliquus hallucis has a very oblique position in
the sole, and hides to a great extent the interosseous muscles.
It lies to the outer side of the flexor brevis hallucis.
284
THE LOWER LIMB
The transversus pedis, or adductor transversus hallucis, is
placed transversely across the heads of the metatarsal bones.
Origin of abductor minimi digiti
Origin of flexor brevis digitorum
Long plantar ligament
External plantar artery and nerve
L Internal plantar artery and nerve
Abductor hallucis
Musculus accessorius
H-— - Flexor longus digitorum
ffM^ Flexor longus hallucis
■KU- Peroneus longus
f External plantar artery
and nerve
Flexor brevis minimi digiti
VAiL « — - Adductor oblkmus hallucis
VVl Flexor brevis hallucis
II
^J1 Adductor transversus
hallucis
Lumbricals
Fig. 103. — Deep Dissection of the Foot ; the Superficial Muscles and also
the Flexor Tendons, etc., have been removed.
The flexor brevis minimi digiti may be recognised from its
lying upon the fifth metatarsal bone.
SOLE OF THE FOOT 285
The deep division of the external plantar nerve and the
plantar arterial arch are partially exposed, but they will be
more fully displayed at a later stage.
Flexor Brevis Hallucis. — This muscle arises from the cuboid
bone and from the slip from the tendon of the tibialis posticus
muscle, which goes to the middle and outer cuneiform bones.
It is narrow and tendinous at its origin, but it soon divides
into two separate fleshy bellies, which are ultimately inserted
upon either side of the base of the proximal phalanx of the
great toe. In the tendons of insertion two large sesamoid
bones are developed. The inner head of the flexor brevis
hallucis is closely connected with the tendon of the abductor
hallucis, and is inserted in common with it. The flexor
brevis hallucis is supplied by the internal plantar nerve.
Adductor Obliquus Hallucis. — The adductor obliquus
hallucis arises from the sheath of the peroneus longus muscle
and from the bases of the second, third, and fourth meta-
tarsal bones. It tapers as it approaches the root of the
hallux, and is inserted, with the outer head of the flexor
brevis hallucis, into the fibular aspect of the base of the
proximal phalanx of the great toe. It is supplied by the deep
division of the external pla?itar nerve.
Adductor Transversus Hallucis. — The transverse adductor
is a second special adductor of the great toe. It springs by a
series of slips from the inferior metatarso-phalangeal ligaments
of the third, fourth, and fifth toes, and proceeds transversely
inwards under cover of the flexor tendons to find insertion
into the fibular side of the base of the proximal phalanx of
the great toe in common with the adductor obliquus hallucis.
Its nerve of supply comes from the deep division of the external
plantar.
Flexor Brevis Minimi Digiti. — The flexor brevis minimi
digiti is a single fleshy slip, which springs from the base of
the fifth metatarsal bone and the sheath of the peroneus
longus tendon. It is inserted into the fibular side of the base
of the proximal phalanx of the little toe. Its nerve of supply
comes from the superficial division of the external plantar nerve.
Dissection.— The adductor obliquus hallucis and the flexor brevis hallucis
must now be detached from their origins and thrown forwards, in order
that the entire length of the plantar arterial arch, and the deep division of
the external plantar nerve, may be displayed. In raising the adductor
hallucis the branch which is given to it by the deep division of the external
plantar nerve must be secured and retained.
286 THE LOWER LIMB
Plantar Arterial Arch (arcus plantaris). — This is the
continuation of the external plantar artery. It extends across
the sole from the base of the fifth metatarsal bone to the
posterior part of the first intermetatarsal interval, where it is
joined by the dorsalis pedis artery. The plantar arch is
deeply placed, it rests upon the interosseous muscles close to
the bases of the metatarsal bones, and it is covered by the
flexor tendons, the lumbrical muscles, and the adductor
obliquus hallucis. It is accompanied by the deep division of
the external plantar nerve and by two vena comites.
The branches which proceed from the plantar arch are : —
1. Articular.
2. Posterior perforating.
3. Digital.
The articular twigs arise from the concavity of the arch,
and run backwards to supply the tarsal joints.
The posterior perforating branches are three in number.
They proceed upwards in the back parts of the outer three
intermetatarsal spaces. Each artery occupies the interval
between the heads of the corresponding dorsal interosseous
muscle. They end on the dorsum of the foot by joining the
three dorsal interosseous branches of the metatarsal artery.
The digital branches are four in number, and are arranged
in the same manner as the digital branches of the superficial
palmar arch in the hand. The first or outermost goes to the
fibular side of the little toe ; the second proceeds forwards in
the fourth interosseous space, and divides to supply the con-
tiguous sides of the fourth and little toes ; the third bifurcates
at the cleft between the third and fourth toes, and gives the
collateral branches to their adjacent sides ; and the fourth
is disposed in a similar manner, and furnishes collateral
branches to the contiguous margins of the second and third
toes.
Each of the inner three digital arteries, at its point of
division, sends upwards in the interosseous space a minute
anterior perforating ' branch, to join the corresponding dorsal
interosseous branch of the metatarsal artery.
Upon the sides of the toes the collateral branches are dis-
tributed in exactly the same manner as the corresponding
arteries of the fingers.
Arteria Magna Hallucis (the plantar digital branch of the
dorsal artery of the foot). — This vessel corresponds with the
SOLE OF THE FOOT
287
arteria radialis indicis and the arteria princeps pollicis of the
hand. It arises from the dorsal artery of the foot in the back
part of the first interosseous space, and proceeds forwards to
the cleft between the great toe and the second toe. Having
supplied a branch to the inner side of the hallux, it divides
Plantar arch
Superficial division of
external plantar nerve
Muscular twigs
Deep division of external
plantar nerve
Nerve to accessorius
Nerve to abductor
minimi digiti
External plantar artery
Nerve to 1st lumbrical
Dorsalis pedis artery
Nerve to flexor brevis
hallucis
Nerve to flexor brevis
digitorum
Nerve to abductor hallucis
Internal plantar artery
Internal plantar nerve
External plantar nerve
Posterior tibial artery
Fig. 104. — Arteries and Nerves of the Sole of the Foot. (Diagram. )
The external plantar nerve and its branches are tinted yellow.
into the collateral branches for the adjacent sides of the great
toe and the second toe.
Deep Division of the External Plantar Nerve. — This ac-
companies the plantar arch in its inward course across the
sole, and ends in the deep surface of the adductor obliquus
hallucis. . In addition to this muscle it supplies all the
interosseous muscles, with the exception of those in the
288 THE LOWER LIMB
fourth space, the adductor transversus hallucis, and the three
outer lumbrical muscles, The twig to the second lumbrical
takes a recurrent course around the anterior border of the
adductor transversus hallucis.
Transverse Metatarsal Ligament. — The adductor trans-
versus hallucis should now be detached from its origin, and
thrown inwards towards the hallux. This brings into view the
transverse metatarsal ligament — a strong fibrous band which
stretches across the heads of the five metatarsal bones. It is
attached to the inferior ligaments of the metatarso-phalangeal
joints. It differs from the corresponding ligament of the
hand, inasmuch as it includes within its grasp the metatarsal
bone of the hallux.
Dissection. — A satisfactory display of the interosseous muscles cannot be
obtained unless the transverse metatarsal ligament be divided between the
heads of the metatarsal bones. The toes can now be separated more freely
from each other, and the interosseous muscles traced to their insertions. It
is well also to reflect at this stage the flexor brevis minimi digiti.
Interosseous Muscles. — The plantar interosseous muscles
are three in number, and are so placed that they adduct the
three outer toes towards a line drawn through the second toe.
They arise from the plantar aspects of the outer three meta-
tarsal bones, and are inserted one upon the tibial side of
each of the corresponding toes. The dorsal interosseous
muscles are four in number. They occupy the four inter-
metatarsal spaces, and consequently they must be dissected
both upon the plantar and dorsal aspects of the foot. They
are arranged so as to abduct the second, third, and fourth
toes from a line drawn through the second toe. They are
inserted, therefore, as follows: the first upon the tibial side of
the second toe ; the second upon the fibular side of the same
toe ; the third upon the fibular side of the third toe ; and the
fourth upon the fibular side of the fourth toe. The slender
tendons of the interosseous muscles are only very slightly
attached to the bases of the proximal phalanges. They are
for the most part inserted into the expansions of the extensor
tendons on the dorsal aspect of the toes.
Tendon of the Tibialis Posticus. — Before leaving the sole
of the foot the dissector must determine the precise insertions
of the tendons of the tibialis posticus and of the peroneus
longus. The tendon of the tibialis posticus is not merely
inserted into the tubercle of the scaphoid. Fibrous slips are
SOLE OF THE FOOT
289
Adductor obliquus hallucis
seen to spread out from it, and these may be traced to every
bone of the tarsus with the exception of the astragalus, and
also to the bases of the second, third, and fourth metatarsal
bones. As it lies under and gives support to the head of the
astragalus, the tendon of the tibialis posticus has developed
within it a sesamoid nodule of fibro-cartilage, or perhaps a
sesamoid bone.
Tendon of the Peroneus Longus. — The tendon of the
peroneus longus turns
round the outer
margin of the foot,
and runs inwards in
the groove on the
under surface of the
cuboid bone across
the sole, to reach the
base of the first meta-
tarsal bone. As it
traverses the sole it
is enclosed in a fibrous
sheath. This sheath
is mainly formed by
fibres derived from the
long plantar ligament.
Open the sheath and
its smooth, glistening
internal surface will
ba displayed. This
appearance is due to
the synovial mem-
brane which lines it.
The tendon is inserted
into the inferior part
of the base of the
first metatarsal bone, and also to a slight degree into the
adjacent part of the internal cuneiform bone. It like-
wise, in some cases, sends a slip to the base of the second
metatarsal bone. As the tendon winds round the cuboid
bone it is thickened, and contains a nodule of fibro-cartilage,
or perhaps a sesamoid bone.
Dissection. — The dissection of the sole of the foot is brought to an end
by sawing through the first metatarsal bone close to its base, and removing
VOL. I 19
Peroneus
longus
Tibialis
posticus
Flexor longus
digitorum
Flexor longus
hallucis
Fig. 105. — The insertions of the Tibialis Posticus
and Peroneus Longus Muscles in the Ri»ht
Foot. (Paterson.)
290
THE LOWER LIMB
its proximal extremity. A good view is thus obtained of the continuity
between the dorsalis pedis artery and the plantar arch.
Anastomosis around the Knee-joint. — The most important
of the anastomoses around the knee-joint are placed on the
anterior aspect of the articulation, and take the form of three
transverse arches. The uppermost of these arterial arcades
passes through the superficial fibres of the quadriceps extensor
close to the upper border of the patella, and is formed by the
union of a branch from the superior external articular artery
with another from the deep branch of the anastomotica.
Deep branch of
anastomotic artery
Vastus in tern us
Superior internal
articular artery
Ligamentum patellae
Internal semilunar _
cartilage
Ligamentum patellae
Inferior internal
articular artery
Internal lateral ligament
Sartorius
Vastus externus
Rectus femoris
Biceps
Superior external
articular artery
Patella
External lateral
ligament
Inferior external
articular artery
External lateral
ligament
Head of fibula
Anterior recurrent
tibial artery
Anterior tibial artery
Fig. 106. — Anastomosis on the front of the Right Knee-joint.
The middle and lower transverse arches are both placed
under cover of the ligamentum patellae. The middle arch runs
across in the fatty tissue close to the lower end of the patella.
The inferior external articular artery, with a branch which
results from the union of a twig from the anastomotica, and
another from the superior internal articular artery, enters into
its formation. The lowest arch lies on the tibia immediately
above its tubercle, and results from the anastomosis of the
recurrent tibial and inferior internal articular arteries. The
upper and middle of these transverse arches are connected,
on each side of the patella, by ascending and descending
branches, which anastomose with one another, and thus
enclose the patella in an irregularly quadrilateral arterial frame-
SOLE OF THE FOOT 291
work. From all sides of this arterial enclosure, twigs are
given off which enter small foramina on the anterior surface
of the patella to supply the osseous substance. Six arteries
therefore take part in the formation of this system of anasto-
moses, on the front and lateral aspects of the joint, viz., the
deep branch of the anastomotica, the two superior and the
two inferior articular branches of the popliteal, and the
anterior recurrent branch of the anterior tibial. In addition
to the twigs which proceed from these to form the arterial
arches, numerous branches are given which spread over the
bones in the form of a close meshwork. During the dissec-
tion of the articulation these vessels will become apparent.
The knee-joint is supplied on its posterior aspect by twigs derived from
all the articular branches of the popliteal. These twigs are variable in
their origin, and the anastomoses which are formed between them are
unimportant and inconstant. They are sometimes supplemented by
another artery, the posterior recurrent tibial. This small vessel is a branch
of the anterior tibial before it leaves the back of the leg. It ascends under
cover of the popliteus muscle, ramifies over the lower part of the ligamentum
posticum "Winslowii, and inosculates with the two inferior articular
branches of the popliteal.
The azygos articular artery is chiefly destined for the supply of the
interior of the joint. It pierces the posterior ligament, passes forwards
between the crucial ligaments, and ramifies in the fatty tissue in that
situation. Its terminal twigs usually anastomose with the intermediate
arch in front of the knee-joint. It will be dissected at a later stage in the
interior of the joint.
Articular Nerves of the Knee- Joint. — The knee-joint is
richly supplied with nerves. Xo less than ten distinct
branches may be traced to it. The anterior crural, the
external popliteal, and the internal popliteal trunks, con-
tribute three twigs apiece to this articulation, and the
obturator furnishes a filament to its posterior aspect. The
(Ulterior crural supplies the joint through branches which
proceed from the nerves to the vastus externus, vastus
internus, and subcrureus. These nerves pierce the fibres of
the quadriceps muscle, and are distributed to the upper and
anterior part of the articulation. The articular branch from
the nerve to the vastus internus is of larger size than the
other two, and it accompanies the deep branch of the
anastomotic artery. The external popliteal nerve gives off —
(1) the superior and inferior external articular nerves : these
accompany the arteries of the same name, and end in fine
filaments, which pierce the capsule of the joint; and (2) the
recurrent articular nerve which accompanies the anterior
I — 19 a
292 THE LOWER LIMB
recurrent tibial artery. This nerve ends chiefly in the tibialis
anticus muscle ; but a fine twig may reach the lower part of
the anterior aspect of the knee-joint. The internal popliteal
nerve furnishes the knee-joint with superior and inferior
internal articular and azygos articular nerves, which accom-
pany the arteries of the same name. The branch from the
obturator nerve descends on the posterior aspect of the
popliteal artery as far as the back of the knee-joint. At this
point it leaves the artery and, inclining forwards, breaks up
into several filaments which separately pierce the posterior
ligament.
ARTICULATIONS.
The dissection of the knee-joint, the ankle-joint, the tibio-
fibular joints, and the various articulations of the foot, may
now be proceeded with. It is possible that the ligaments may
have become hard and dry. If this be the case, soak the
joints in water for an hour or two.
Knee-Joint.
In the knee-joint (articulatio genu) three bones are in
apposition, viz., the lower end of the femur, the upper end
of the tibia, and the patella. It is the largest and most
complicated articulation in the body ; and if the bones be
examined in the skeleton, the joint presents an apparent
insecurity, because the bony surfaces show little adaptation
the one to the other. In reality, however, the knee-joint is
very strong, and very rarely suffers dislocation on account of
the strength of the ligaments which retain the bones in place.
The ligaments on the exterior of the joint are : —
1. The capsular ligament.
2. Two lateral ligaments — external and internal.
3. The ligamentum patellae (or anterior ligament).
4. The posterior ligament.
Dissection. — The popliteal vessels and nerves, and the muscles
surrounding the knee-joint, must be removed. Portions of the tendons of
the biceps, semimembranosus, sartorius, semitendinosus, gracilis, and
popliteus, together with small pieces of the heads of the gastrocnemius,
should be left in place in order that their connection with the ligaments of
the joint may be studied. The quadriceps extensor may be divided about
ARTICULATIONS
293
three inches above the patella, and the lower part allowed to remain in
position, further, the various articular arteries which surround the joint
should be followed to their terminations.
Capsule (capsula articularis). — The capsule of the knee-
joint, together with the internal and posterior ligaments, forms
Impression of ex-
ternal semilunar
cartilage
External tibial
surface
External lateral
ligament
rendon of biceps
Anterior superior \ IfK \
io-fibular ligament tfrrfitj
External lateral
ligament
Opening in inter-
•sseous membrane for
interior tibial vessels
Patellar surface of femur
Semilunar facet for
patella
Internal tibial
surface
Posterior crucia
ligament
Anterior crucial
ligament
Transverse ligt.
Internal semi-
lunar cartilage
Internal lateral
igament
Ligt. patellae
Inner perpendicular
facet on patella
Fig. 107. — Dissection of Knee-joint from the front. The Patella
has been thrown down.
a complete investment for the articulation. In the upper and
front part of the joint it is deficient, but here its place is taken
by the common tendon of the quadriceps extensor muscle.
The capsule may be regarded as an aponeurotic expansion
on the front of the articulation, which fills up the intervals
between the two lateral and the anterior ligaments. The
fascia lata and expansions from the surrounding tendons enter
294
THE LOWER LIMB
External lateral
ligament
Popliteus
External semi-
lunar cartilage
into its formation. Thus, on the outer aspect, it is largely
composed of the ilio-tibial band of fascia lata as this proceeds
downwards to its attachment to the tibia. Traced backwards,
the capsule will be seen to be prolonged over, and to hide
from view, the external lateral ligament. On the inner side
of the limb it receives expansions from the sartorius and semi-
membranosus, and fuses with the internal lateral ligament.
Ligamentum Patellae. — This forms the anterior ligament of
the knee-joint, and constitutes, at the same time, the tendon
of insertion of the quadriceps extensor muscle. By the re-
moval of the capsular expansion from its surface it may be
fully exposed and its margins
denned.
The ligamentum patellce is a
strong band, about two inches
long, which is attached above
to the apex and lower border
of the patella, and below to
the lower part of the anterior
tubercle of the tibia. Its super-
ficial fibres are directly con-
tinuous over the surface of the
patella with the central part
of the common tendon of the
quadriceps extensor. Its deep
surface rests upon the infra-
patellar pad of synovial fat, and
upon a small bursa which intervenes between it and the
upper part of the anterior tubercle of the tibia.
Dissection. — The external lateral ligament may be exposed by removing
the part of the capsule which is formed by the ilio-tibial band of fascia lata,
and also the prolongation which this gives backwards over the ligament.
By this proceeding the inferior external articular artery will be displayed
as it extends forwards to the front of the joint.
External Lateral Ligament (ligamentum collateralefibulare).
— This is rounded and cord-like. It stands well away from
the joint, and is attached above to a tubercle on the outer
tuberosity of the femur. Below, it is fixed to a depression
on the head of the fibula in front of the styloid process.
It is closely associated with the tendon of the biceps and
the tendon of the popliteus. It splits the tendon of the
biceps into two pieces, and extends vertically downwards
Biceps
Fig. 108. — The External Lateral
Ligament of the Knee-joint.
ARTICULATIONS 295
to its fibular attachment between them. The tendon of
the popliteus takes origin from the outer tuberosity of the
femur below and in front of the femoral attachment of the
external lateral ligament. As the tendon proceeds backwards
it is placed under cover of the ligament.
An additional slip is sometimes described as the posterior part of the
external lateral ligament. When present it is attached to the femur, under
cover of the outer head of the gastrocnemius, in connection with the
posterior ligament. Below, it is implanted into the styloid process of
the fibula.
Internal Lateral Ligament (ligamentum collaterale tibiale).
— The internal lateral ligament is a long flat band, broader in
the middle than at either extremity, which springs from the
inner tuberosity of the femur below the adductor tubercle.
As it descends it inclines slightly forwards, and finally it gains
attachment to the upper part of the shaft of the tibia below
the internal tuberosity. The main part of the tendon of
the semimembranosus extends forwards under cover of its
posterior border to gain an insertion into the tuberosity of
the tibia, whilst lower down the inferior internal articular
vessels are carried forwards between it and the bone. The
tendons of the sartorius, gracilis, and semitendinosus, lie upon
its superficial surface, but are separated from it by an inter-
vening bursa.
Posterior Ligament. — The posterior ligament stretches
from the external to the internal lateral ligament. Above, it
is fixed to the upper margin of the intercondyloid notch,
whilst on either side it becomes incorporated with the corre-
sponding head of the gastrocnemius. Below, it is attached
to the posterior border of the upper end of the tibia. A
strong slip derived from the tendon of the semimembranosus
strengthens the ligament on its posterior aspect. This band
passes upwards and outwards towards the external condyle
of the femur.
Sometimes the term "posterior ligament" (ligamentum posticum
Winslowii) is restricted to this oblique band from the semimembranosus,
and the remainder of the ligament as described above is then regarded as a
portion of the capsule.
The posterior ligament presents a number of apertures for the entrance
of blood-vessels and nerves into the interior of the joint. The azygos artery
is the most conspicuous of these vessels. An opening may likewise some-
times be observed over the upper part of the internal condyle of the femur.
Through this protrudes a pouch of synovial membrane which forms a bursa
under the inner head of the gastrocnemius. As a rule, however, this bursa
296
THE LOWER LIMB
is independent of the knee-joint, and the aperture in the ligament is absent.
Another opening is situated in the outer part of the ligament, and gives
exit to the tendon of the popliteus.
Dissection. — A vertical incision should be made into the joint on either
side of the patella and ligamentum patellae, in order that the common
Tendon of adductor
magnus muscle (cut)
Inner head of gas
trocnemius (cut)
Posterior ligament or
ligament of Winslow
Bursa beneath tendon
of semimembranosus
Tendon of semimem-
branosus muscle (cut)
Posterior ligament
(oblique slip)
Internal lateral
ligament
Popliteal surface of femur
Plantaris muscle (cut)
Outer head of
gastrocnemius
(cut)
Long external
lateral ligament
Short external
lateral ligament
Popliteus
muscle (cut)
Biceps flexor
cruris muscle
(cut)
Popliteal
Popliteus muscle
Head of fibula
Popliteal surface of tibia
Fig. 109. — The Knee-joint. Posterior view.
extensor tendon and the patella may be thrown downwards over the upper
end of the tibia. The joint is now opened from the front, and the parts in
the interior may be observed.
Interior of the Joint. — First note the great pad of soft fat
which is placed on the deep surface of the ligamentum patellae.
In vertical section this fatty mass is triangular in form (Fig. 1 10).
It is termed the infra-patellar pad, and it fills up the interval
between the patella, femur, and tibia, and adapts itself to
the varied forms which this recess adopts in the different
ARTICULATIONS 297
movements of the joint. It is separated from the interior
of the joint by a covering of synovial membrane, and from
its surface a band of this membrane extends backwards and
upwards to the intercondyloid fossa of the femur, where it
is attached. This band is termed the ligamentum mucosum.
As it approaches the femur it becomes narrow and slender ;
but, before it fairly rises from the surface of the infrapatellar
pad, it is broad and triangular, and presents two free margins
which extend along the lateral borders of the patella in its
lower part, and receive the name of ligamenta a/arm (plicae
alares). It must be clearly understood that these are not
ligaments in the ordinary sense of the word, but merely folds
of synovial membrane.
Within the joint the dissector is now able to recognise :
1. The two crucial ligaments.
2. The two semilunar cartilages.
Synovial Membrane. — This is the most extensive membrane
of the kind in the body. It lines the deep surface of the
ligamentous structures which surround the joint, and extends
upwards for at least an inch beyond the articular surface of
the femur, in the form of a great cul-de-sac, under cover of the
common tendon of the quadriceps. By its upper part this
pouch usually communicates by an orifice of greater or less
width with a large bursa which lies at a higher level upon
the front of the femur. The synovial membrane covers both
surfaces of the semilunar cartilages, gives a partial investment
to the crucial ligaments, and contributes a pouch-like prolonga-
tion along the tendon of the popliteus. The synovial invest-
ment of the crucial ligaments is not complete, and is carried
forwards upon them from the posterior wall of the joint,
The prolongation upon the tendon of the popliteus extends
downwards between the external semilunar cartilage and the
back part of the upper end of the tibia. It facilitates the play
of the tendon over that bone, and comes very close to the
upper part of the superior tibio-fibular joint. Indeed, the
synovial membrane of this joint may, in some cases, be found
continuous with it.
Dissection. — Divide the ligamentum mucosum and remove the infra-
patellar pad of fat. The bursa between the ligamentum patellae and the
upper part of the anterior tubercle of the tibia may now be opened and
examined. Next dissect away the posterior ligament of the joint and trace
the azygos articular artery, which pierces it, forwards to the crucial
298
THE LOWER LIMB
ligaments. It will now be seen that the posterior surface of the posterior
crucial ligament is not covered by synovial membrane, and that it is con-
nected by areolar tissue to the deep surface of the posterior ligament.
Define the attachments of the crucial ligaments by removing the synovial
membrane which is wrapped round them and the areolar tissue in connec-
tion with them. The semilunar cartilages should also receive the attention
of the dissector, and the manner in which their fibrous pointed extremities
are fixed to the tibia must be studied. At this stage the changes produced
in the degree of tension of the crucial ligaments, and the change brought
about in the position of the semilunar cartilages by movements of the joint,
should be examined.
Movements at the Knee-joint. — The movements of the knee-joint are
those of flexion and extension. The leg can be bent back until the
Adductor magnus
Popliteal artery
Semimembranosus
Inner head of
gastrocnemius
Inferior internal
articular artery
Popliteal vein
Popliteus
Popliteus
r Synovial bursa
Common tendon of
quadriceps
Synovial membrane
Patella
Infra-patellar
pad of fat
Bursa
Ligamentum
patellae
Tibia
Fig. no. — Vertical antero-posterior section through the Knee-joint.
prominence of the calf comes into contact with the posterior aspect of the
thigh ; but in extension the movement is brought to a close when the leg
comes into a line with the thigh. In this position the joint is firmly locked,
and the anterior crucial, the lateral, and the posterior ligaments being fully
stretched, the leg and thigh are converted into a rigid column of support.
In flexion, however, the lateral and posterior ligaments are relaxed, and a
certain amount of rotation of the tibia upon the femur is allowed.
But the movements of flexion and extension at the knee-joint are by no
means so simple as at first sight they might appear to be, and to obtain
some appreciation of them it is necessary to subject the opposed articular
surfaces to a close scrutiny. Flex the joint acutely, and examine the
cartilage-covered surface of the lower end of the femur. It consists of an
anterior trochlear portion for the patella, and two condylar surfaces which
move on the tibia. The trochlea is separated from the surface of the
external condyle by a faintly marked groove, which takes a slightly curved
course from the external border of the lower end of the femur inwards and
ARTICULATIONS 299
backwards to the fore part of the intercondyloid fossa. At either extremity
this groove widens out into a distinct depression. In full extension the outer
depression rests upon the anterior part of the external semilunar cartilage,
whilst the inner depression rests upon the anterior border of the external
tubercle of the spine of the tibia (Bruce Young). The line of demarcation
between the trochlea and the lower surface of the internal condyle of the
femur is not so distinct. Close to the inner margin of the bone there is a
depression which, in full extension, rests upon part of the anterior horn of
the internal semilunar cartilage (Bruce Young) : but external to this the
trochlear surface is prolonged backwards for a certain distance along the
anterior and inner margin of the intercondyloid fossa. A portion of the
internal condyle is thus included in the trochlear surface, viz. , the portion
skirting the inner border of the anterior part of the intercondyloid foss .
and this is termed the " crescentic facet '' of the internal condyle.
The deep surface of the patella may next be examined I Fig. 107), and its
movements in connection with flexion and extension of the knee-joint studied.
A high vertical ridge divides its deep surface into a large external and a
smaller internal area. Each of these is still further subdivided by faint ridges
on the cartilage which coats the surface. A faint line upon the inner area of
the patella descends in a vertical direction so as to mark off a narrow strip
close to the inner border of the bone. This strip is called the internal
perpendicular facet. Two horizontal lines extend outwards from the outer
border of the internal perpendicular facet to the outer border of the bone,
and subdivide the remainder of the inner area and the whole of the outer
area into three facets each. In a well-marked patella, therefore, the deep
cartilage-covered surface shows seven facets, viz. , an upper pair, an inter-
mediate pair, a lower pair, and an internal perpendicular facet (Goodsir).
The faceted appearance of the deep surface of the patella indicates that
in the movements of this bone upon the trochlear surface of the femur the
entire articular surface is never in contact with the femur at the same time.
In flexion and extension of the knee, the patella moves downwards and
upwards in a curved path, the concavity of which looks upwards, backwards,
and outwards. The different facets come into contact and break contact
with the femur in regular succession. Let us suppose the knee-joint to be
acutely flexed : in this condition of the limb the internal perpendicular facet
of the patella rests upon the crescentic facet of the internal condyle of the
femur, while the outer of the two upper patellar facets is in contact with the
outer lip of the trochlear surface of the femur. No part of the patella
touches the inner lip of the trochlear surface. As the leg is moved from
the fully flexed to the fully extended position, the two upper facets, then
the two intermediate facets, and, lastly, the two lower facets, come
successively into contact with the trochlear surface of the femur (Goodsir).
In Fig. 1 10 the position of the patella in the fully extended knee is
exhibited.
Now examine the condylar surfaces of the femur (Fig. 107). The posterior
two-thirds of the internal condyle will be seen to be of equal extent with,
and parallel to, the external condyle. The anterior third of the internal
condyle, however, turns obliquely outwards to join the trochlear surface.
The external condylar surface has no part corresponding with this, and its
presence in connection with the internal condyle gives rise to the " screw-
home " movement, which is so characteristic of the knee-joint when fully
extended. At the commencement of flexion and at the completion of
extension there is a screw movement, or a movement of rotation of the
tibia and femur on each other. As the leg is moved forwards from the
condition of acute flexion, the condyles of the femur roll and glide over the
surfaces on the upper end of the tibia until the surface of the external
3oo THE LOWER LIMB
condyle, and the corresponding part of the internal condyle, are exhausted.
This movement of the femoral condyles has been compared to that of " a
wheel partially restrained by a drag " (Goodsir). Any additional movement
beyond this point must necessarily take place in connection with the anterior
oblique third of the internal condyle. This produces a rotation or screw-
like motion of the femur inwards. The internal condyle travels backwards
round the spine of the tibia, and the anterior part of the intercondyloid
notch comes into contact with the anterior crucial ligament and the internal
tubercle of the tibial spine (Bruce Young). The joint is now "screwed
home " or locked. In the initial stage of flexion the reverse movement
must be accomplished. The unlocking of the joint can only be brought
about by a rotation inwards of the tibia, or a rotation outwards of the
femur.
When fully extended, as we have seen, the joint is locked, and the
posterior, lateral, and anterior crucial ligaments are tense. The limb is
converted into a rigid column, and the upright posture is thereby main-
tained with the smallest possible degree of muscular exertion.
The muscles which operate upon the bones of the leg so as to produce
flexion and extension of the limb at the knee-joint are : — (i) extensors, the
four parts of the quadriceps extensor ; (2) flexors, the biceps, popliteus,
sartorius, gracilis, semitendinosus, and semimembranosus. Of these, only
one is inserted on the outer side of the limb, viz. , the biceps. The other
five are inserted into the tibia on the inner side of the leg.
Dissection. — In order to obtain a proper view of the attachments of the
crucial ligaments the following dissection should be made : — The femur
must be sawn across about two inches above its lower articular surface.
When this is done the saw should be applied to the cut surface of the lower
part of the bone, and a vertical cut made through it so as to divide it into
a right and a left lateral portion. The saw-cut should be planned to end
inferiorly in the intercondyloid fossa between the condyles and between
the upper attachments of the two crucial ligaments. By this procedure
the crucial ligaments can be studied singly, or together, and their relation
to the lateral ligaments of the joint can be examined. It will be seen that
the external lateral ligament and the anterior crucial ligament constitute a
pair of ligaments appropriated by the external condyle, to either side of
which they are fixed ; while the internal lateral and the posterior crucial
ligaments belong to the internal condyle of the femur, and are attached on
either side of it. When this relationship is observed, the internal lateral
ligament may be divided. This will, in a measure, set free the internal
condyle, and give greater space for the study of the crucial ligaments.
Crucial Ligaments (ligamenta cruciata genu). — These are
well named, because they cross each other like the limbs of
the letter X in the interval between the two condyles ol
the femur. This crucial arrangement is seen whether they are
viewed from the side, by the removal of the lower part of one
condyle, or from the front or the back of the joint. The
anterior crucial ligament is attached to the external condyle,
whilst the posterior is fixed to the internal condyle of the
femur. They are consequently sometimes termed external
and internal.
The anterior crucial ligament springs from the intermediate
ARTICULATIONS
301
rough area on the upper surface of the tibia, immediately in
front of the inner tubercle which surmounts the tibial spine.
From this it proceeds upwards, backwards, and outwards, to
gain attachment to the posterior part of the inner surface of
the external condyle of the femur (Fig. 95, p. 262).
The posterior crucial ligament springs from the posterior
Tendon of insertion
of adductor magnus
muscle (cut)
Popliteal surface of femur
\nterior crucial ligament
Tendon of poplites
muscle (cut)
Accessory attach-
ment of external
imilunar cartilage
nternal semilunar
cartilage
Posterior crucial
ligament
Tendon of
semimem-
•anosus muscle (cut)
Internal lateral
ligament
Popliteal surface
of tibia
xternal semilunar
cartilage
Groove on tibia for ten
don of popliteus muscl«
Capsule of superior
tibio-fibular articulatio;
External lateral
ligament
Posterior superior tibic
fibular ligament
Head of fibula
Fig. hi. — The Knee-joint opened from behind by the removal of the
Posterior Ligament.
sloping part of the intermediate rough area on the upper
surface of the tibia, behind the tibial spine, and behind also
the attachments of the posterior horns of both semilunar
cartilages. It proceeds upwards, forwards, and somewhat
inwards, and, crossing the anterior crucial ligament, is attached
in the fore part of the intercondyloid fossa to the outer surface
of the anterior oblique portion of the internal condyle. It
3o2 THE LOWER LIMB
receives one, or sometimes two, strong slips from the posterior
horn of the external semilunar cartilage (Fig. 95, p. 262).
The anterior crucial ligament is tight in extension, and the
posterior crucial ligament is tight in flexion of the knee-joint.
Semilunar Cartilages. — These are two crescent! c plates of
fibro-cartilage which are placed on the condylar surfaces of the
tibia. They deepen the surfaces upon which the condyles of
the femur roll, and, being movable, they fill up the gaps which
would otherwise arise during the movements of the joint.
Each cartilage presents two fibrous extremities, or horns,
which are attached to the rough intermediate surface on the
upper end of the tibia. They are thick towards the circum-
ference of the joint, but thin away to a fine free concave
edge in the opposite direction. Both surfaces are smooth
and covered with synovial membrane. They do not cover
the entire extent of the condylar surfaces of the tibia. The
central parts of the latter, as well as the sloping surfaces of
the tubercles of the tibial spine, are free. On raising the
cartilages from the surface upon which they rest, distinct
impressions similar in shape and extent are seen on the sub-
jacent encrusting cartilage of the tibia.
Dissection. — Carefully define the attachments of the fibrous horns of the
semilunar cartilages.
The external semilunar cartilage (meniscus lateralis) is
usually somewhat thicker around its circumference than the
internal cartilage. It forms the segment of a smaller circle,
and its horns being fixed to the tibia close together, a very
nearly complete circle is formed. The anterior fibrous horn
is attached, immediately in front of the tibial spine, to the
outer side of and partly under cover of the attachment of the
anterior crucial ligament. The posterior horn is fixed to the
summit of the tibial spine in the interval between the two
tubercles. It likewise gives a strong slip to the posterior
crucial ligament. The external lateral ligament is not in
contact with the external semilunar cartilage. It is separated
from it by the tendon of the popliteus, and the impress of the
tendon is left on the cartilage in the form of a faint smooth
groove on its outer and posterior border. Behind, its circum-
ference is attached to the posterior ligament.
The i?itemal semilunar cartilage (meniscus medialis) is semi-
circular in form, and forms the segment of a much larger
ARTICULATIONS
3°3
circle than the external cartilage. Its anterior fibrous horn is
fixed to the fore part of the intermediate rough area of the
tibia in front of the attachment of the anterior crucial liga-
ment ; its posterior horn is attached to the back part of the
intermediate rough area of the tibia, behind the tibial spine,
and in front of the attachment of the posterior crucial
ligament. The circumference of this cartilage is closely con-
nected with the deep surface of the internal lateral ligament.
Transverse Ligament (ligamentum transversum genu). —
This is a fibrous band which stretches across from the fore-
part of one semilunar cartilage to the corresponding part of
the other, constituting thereby a bond of union between them.
Fig. 112. — Parts attached to the upper end of the Right Tibia.
Transverse ligament.
Anterior cornu of internal semilunar
cartilage.
Anterior crucial ligament.
Internal tubercle of spine of tibia.
Internal semilunar cartilage.
Posterior cornu of internal semilunar
cartilage.
Posterior crucial ligament.
Fasciculus from external semilunar
cartilage to posterior crucial ligament.
Posterior cornu of external semilunar
cartilage.
External tubercle of spine of tibia.
External semilunar cartilage.
Anterior cornu of external semilunar
cartilage.
Dissection. — The condyles of the femur should now be detached by
dividing the external lateral ligament and the crucial ligaments close to
their femoral attachments.
Attachment of Parts to Upper Surface of the Tibia. —
The ligamentous structures are attached to the intermediate
area on the upper surface of the tibia in the following order
from before backwards: — (i) The anterior horn of the
internal semilunar cartilage on the inner side of the extreme
anterior part of the area. (2) The anterior crucial ligament
3°4
THE LOWER LI Ml]
and the anterior horn of the external semilunar cartilage :
these are placed side by side, but the attachment of the
former, which lies to the inner side, overlaps that of the
external semilunar cartilage. (3) The posterior horn of the
external semilunar cartilage on the summit of the tibial spine
between its two tubercles. (4) The posterior horn of the
internal semilunar cartilage immediately behind the tibial
spine. (5) The posterior crucial ligament at the hinder part
of the area.
Ankle-Joint.
The ankle-joint (articulatio talocruralis) is
articulation of the ginglymus or hinge variety.
a diarthrodial
The articula-
Anterior fasciculus of ex-
ternal lateral ligament
Fibular facet
Anterior inferior tibio-
fibular ligament
External malleolus
Middle fasciculus of
external latera
ligament
Posterior inferior tibio-
fibular ligament
Posterior fasciculus of
external lateral ligament
Internal lateral or
deltoid ligament
Internal malleolus
Transverse inferior
tibio-fibular ligament
Synovial pad
of fat
Fig. 113.
-Articular Surfaces of Tibia and Fibula which articulate
with the Astragalus.
tion takes place between the bones of the leg and the astragalus,
and the weight of the body is transferred through it to the
foot. It is a joint of great strength ; its stability being en-
sured not only by the powerful ligaments which surround it,
but also by the close interlocking of the articulating surfaces.
The bones which enter into the formation of the ankle-
joint are the lower ends of the tibia and fibula and the
superior surface of the astragalus. The lower ends of the leg
bones are very firmly united together by an interosseous and
other ligaments which give the joint a certain amount of
elasticity or spring. They form a deep hollow resembling a
mortice. The upper surface of the astragalus is received into
this cavity.
ARTICULATIONS
3°5
The ligaments of the ankle-joint are :-
I. The anterior.
3. The external lateral.
2. The posterior.
4. The internal lateral.
Dissection. — The remains of the annular ligaments, together with the
tendons which are in relation to the joint, should be removed and the
ligaments defined. The anterior and posterior ligaments should be first
dissected. They may then be removed in order to bring the powerful
Lower end of shaft of tibia 7
Groove on interna
malleolus f^r tendon of-
tibialis posticus
Trochlear surface of
astragalus
Internal lateral j
ligament I
Fibrous sheath for tendon of
flexor longus hallucis
Sustentaculum tali
■koi longus hallucis tendon (cut)
Posterior calcaneo-astragaloid
ligament
Tibio-fibular interosseous
membrane
Lower end of shaft of fibula
Posterior inferior tibio-fibular
ligament
Transverse inferior tibio-fibular
ligament
Facet on astragalus for trans-
verse inferior tibio-fibular
igament
Posterior fasciculus of external
lateral ligament
Middle fasciculus of external
lateral ligament
Tuberosity of os calcis
FlG. 114. — Ankle-joint dissected from behind with part of the Capsular
Ligament removed.
external and internal lateral ligaments more fully into relief, and at the
same time display the articulating surfaces, and thus permit the play of
these surfaces to be seen when the joint is flexed and extended.
Anterior and Posterior Ligaments. — These arc feeble bands
which are placed in front of and behind the joint. They
are attached to the margins of the articulating surfaces,
except in front and below, where the anterior ligament is
vol. 1 — 20
;o6
THE LOWER LIMB
fixed to the neck of the astragalus. The fibres of these
ligaments have for the most part a transverse direction.
External Lateral Ligament.— This is a composite ligament
and consists of three distinct bands — an anterior, a middle,
and a posterior. The anterior fasciculus (ligamentum talo-
fibular anterius) is a flattened band which passes from the
anterior border of the lower end of the fibula to the outer and
back part of the neck of the astragalus. The middle fasciculus
Fibula
Posterior inferior tibio-
fibular ligament
Articular surface of
astragalus
Posterior fasciculus of
external lateral ligament
of ankle
Middle fasciculus of
external latera
ligament of ankle
Posterior c;
astragaloid 1
Os calcis
Tibia
Anterior inferior tibio-fibular ligament
Articular surface of astragalus
Anterior fasciculus of external lateral
ligament of ankle
/ " Dorsal astragalo-navicular ligament
Astragalo-navicular joint
External calcaneonavicular liganv
Dorsal scapho-cuneifom
", andscapho-cuboid ligam
V* ^*8fe^ Middle cuneiform
lH Ex
ternal cuneiform
Cuboid
] torsal calcaneo-cuboid ligament
Calcaneo-cuboid joint
Tendon of peroneus longus
Interosseous calcaneo-astragaloid ligament
Calcaneo-astragaloid joint
External calcaneo-astragaloid ligament
Fig. 115. — Ligaments on the Outer Aspect of the Ankle-joint and on
the Dorsum of the Tarsus.
(ligamentum calcaneo-fibulare), round and cord-like, passes
from a point a little in front of the tip of the external malleolus to
the external surface of the calcaneum. The posterior fasciculus
(ligamentum talofibulare posterius), the strongest of the three,
is a powerful band of fibres which proceeds almost horizon-
tally inwards from the deep pit behind the lower articular
surface of the fibula to a prominent tubercle on the back of
the astragalus.
This tubercle is sometimes detached, and forms a supernumerary tarsal
bone which may represent the os trigoniun found in some mammals. In
such cases it has been mistaken for a fracture.
ARTICULATIONS
3°7
Internal Lateral Ligament (ligamentum deltoideum). — This
presents a triangular form. Its apex is directed upwards and
is attached to a shallow pit on the under border of the inner
malleolus. Its fibres diverge as they descend, and are attached
in a continuous layer from before backwards to the scaphoid,
Fig. 116. — Ankle- and Tarsal-joints from the Tibial Aspect.
i. First tarsometatarsal joint (opened)
2. Tendon of tibialis amicus muscle (cut)
j. Internal scapho-cuneiform joint (opened)
4. Dorsal scapho-cuneiform ligament
5. Head of astragalus
6. Dorsal astragalo-scaphoid ligament
7. Trochlear surface of astragalus
8. Internal malleolus
9. Internal lateral or deltoid ligament of
the ankle
10. Trochlear surface of astragalus
11. Groove for tendon of tibialis posticus
muscle on inferior calcaneo-scaphoid
ligament
u. ( »roove and tunnel for the tendon of
flexor longus hallucis muscle
13. Os calcis
14. Sustentaculum tali
15. Tendon of tibialis posticus muscle (cut)
16. Long plantar ligament
astragalus, sustentaculum tali, and behind this to the astragalus
again.
Synovial Membrane. — The synovial membrane lines the
ligaments above described, and sends a small process up-
wards between the tibia and fibula. It is thrown into a
.-I
08 THE LOWER LIMB
transverse fold in front, when the joint is flexed, and into a
similar fold behind when the joint is extended.
Movements. — The movements which take place at the ankle-joint are
— (1) flexion (dorsal-flexion); (2) extension (plantar-flexion); and (3) a
very limited degree of lateral movement (abduction and adduction) when
the foot is fully extended. The two principal movements (flexion and
extension) take place around a horizontal axis, which is not transverse, but
which is directed outwards and 1 ackwards, so that it is inclined to the
median plane of the body at an angle of about 6o° (Krause). This
horizontal axis passes through or near the interosseous canal between the
os calcis and astragalus (Ilenle). As the articular cavity formed by the
tibia and fibula, and also the part of the astragalus which plays in it, are-
broader in front than behind, it follows that the more completely the
ankle-joint is flexed, the more tightly will the astragalus be grasped
between the two malleoli. In the erect position the astragalus is held
firmly in the bony socket, and portions of its articular surface project both
in front of and behind the tibia. The centre of gravity is placed in front
of the ankle-joint, and in this way the bones are kept firmly locked.
When, on the other hand, the ankle-joint is fully extended (as when we
rise on tip-toe) the narrower posterior part of the astragalus is brought into
the socket, and thus a limited amount of lateral movement is allowed. In
flexion the middle and posterior fasciculi of the external lateral ligament,
the greater part of the internal lateral ligament, and the posterior ligament
are put on the stretch. In extension the anterior fasciculus of the external
lateral ligament, the anterior fibres of the internal lateral ligament, and
the anterior ligament are rendered tense.
The Muscles principally concerned in producing dorsi-flexion of the
foot at the ankle-joint are the tibialis anticus and the peroneus tertius ;
those which operate as plantar-flexors are the superficial muscles of the
calf, the tibialis posticus, and the peroneus longus and brevis.
TlBIO-FIBULAR JOINTS.
The fibula articulates with the tibia by both its upper and
lower extremity. Each of these joints is provided with a
synovial membrane and possesses its own appropriate liga-
ments. The interosseous membrane which occupies the
interval between the shafts of the bones may be regarded as
a ligament common to both joints.
Dissection. — Preparatory to the examination of the tibio-fibular joints the
foot must be removed by dividing the internal lateral ligament and the
three parts of the external lateral ligament of the ankle-joint. The muscles
must also be detached from both aspects of the interosseous membrane
and the bones of the leg. The ligaments may now be defined.
Interosseous Membrane (membrana interossea cruris). —
This is a strong membrane which stretches across the interval
between the two bones of the leg, and greatly extends the
surface for the origin of muscles. It is attached on the one
hand to the external border of the tibia, and on the other
ARTICULATIONS 309
to the interosseous ridge which descends on the internal
surface of the fibula. It is composed of strong oblique fibres,
which take a direction downwards and outwards from the tibia
to the fibula. An oval opening in its upper part, immediately
under the external tuberosity of the tibia, is present for the
passage of the anterior tibial vessels, whilst a small aperture a
short distance above the ankle-joint, marks the {joint where
the membrane is pierced by the anterior peroneal artery.
Superior Tibio-fibular Joint (articulatio tibiofibularis). — At
this joint the bones are held in apposition by an anterior
and a. posterior ligament, which pass from the outer tuberosity
of the tibia downwards and outwards to be attached to the
head of the fibula. The posterior ligament is the weaker
of the two, and upon its upper part the tendon of the popliteus
with its synovial investment rests. This investment is a
prolongation from the synovial membrane of the knee joint,
and in some cases it will be found to be directly continuous
with the synovial membrane which lines the superior tibio-
fibular joint.
The relation of the tendon of the biceps to this joint
must not be lost sight of. Attached for the most part to the
head of the fibula, its fibres stretch over the front of the joint.
Some of its tendinous fibres also obtain insertion into the
outer tuberosity of the tibia. Firm support is in this way
contributed to the superior tibio-fibular joint.
Inferior Tibio-fibular Joint (syndesmosis tibiofibularis;
(Figs. 1 13 and 114). — This articulation is constructed upon a
stronger plan, because upon its security the strength of the
ankle-joint very largely depends. Only a very narrow strip
of the lower part of each of the opposing surfaces of the bones
is articular and coated with cartilage. Above this, the surfaces
are rough, and are held together by an exceedingly strong
interosseous ligament, composed of short fibres which pass
directly between the bones.
In addition to this interosseous ligament there are- :
i. An anterior ligament.
2. A posterior ligament
3. An inferior transverse ligami
The anterior and posterior ligaments arc flat strong bands
which pass from the tibia to the fibula, in an oblique direc-
tion, outwards and downwards.
The transverse ligame?it lies under cover of the lower part
3io
THE LOWER LIMB
of the posterior ligament, and to see it properly the latter
should be divided. It is a strong narrow band of yellowish
fibres, which takes a transverse course on the back of the
joint and is firmly attached to both tibia and fibula, filling up
the interval between them. It forms a part of the tibio-fibular
socket for the astragalus at the ankle-joint (Figs. 113 and 114);
and on the upper aspect of the articular surface of the astra-
galus, the area over which it plays is usually easily distinguished.
M—
Fig. 117. — Vertical section through the Foot, along a line
stretching from the centre of the heel behind to the
centre of the great toe in front. ( From Luschka. )
1. Tibia.
2. Astragalus.
3. Os calcis.
4. Scaphoid.
5. Internal cuneiform.
6. First metatarsal.
7 & 8. Phalanges of hallux.
9. Sesamoid bone.
10. Tendo Achillis.
11. Bursa between tendo Achillis and
os calcis.
12. Tendon of extensor longus hallucis.
13. Tendon of flexor longus hallucis.
14. Plantar fascia (central part).
15. Thick superficial fascia of heel.
Dissection. — To see the interosseous ligament of the inferior tibio-fibular
joint the bones of the leg may be sawn through about two inches above
the lower end of the tibia, and then divided with the saw from above
downwards in a vertical-transverse, or coronal direction. This cut should
be planned so as to pass through the inferior tibio-fibular joint. The short
strong fibres of the interosseous ligament will then be seen, and also the
short narrow articular interval between the lower portions of the opposing
surfaces of the bones. The synovial membrane which lines this is a
continuation upwards of the synovial membrane of the ankle-joint.
ARTICULATIONS 311
Articulations of the Foot.
The articulations of the foot are very numerous. They
consist of:
1. The tarsal, tarsometatarsal, and the inter-metatarsal joints.
2. The metatarsophalangeal joints.
3. The interphalangeal joints.
The bones which enter into these articulations are the
seven tarsal bones, the metatarsal bones, and the phalanges.
The tarsal and metatarsal bones are bound together by inter-
osseous, plantar, and dorsal ligaments, and are disposed in the
form of two arches, viz., a longitudinal and a transverse. The
integrity of these arches is maintained partly by the tension
of the ligaments and partly by the direction of the articulating
surfaces of the bones.
The longitudinal arch presents a greater height and a wider
span along the inner than along the outer side of the foot.
The astragalus is placed on the summit of this arch and forms
its keystone. The posterior pillar of the longitudinal plantar
arch is short and solid, being formed by the os calcis alone ;
the anterior pillar, much longer, is composed of several bones,
viz., the scaphoid, the cuboid, the three cuneiforms, and the
metatarsus. Further, the anterior pillar may be considered
as being formed of an inner column composed of the scaphoid,
the three cuneiform, and the three inner metatarsal bones,
and an outer column composed of the cuboid and the two
outer metatarsal bones. The weight of the body is trans-
mitted to the summit of the arch through the astragalus,
and the most important ligaments concerned in the preven-
tion of excessive flattening of the arch are the inferior
calcaneo- scaphoid, the two plantar calcaneo -cuboid ligaments,
and the various slips of the tendon of the tibialis posticus
as they pass to find attachment to the different tarsal and
metatarsal bones. The plantar fascia also acts powerfully
in this way : connecting as it does the extremities of the
two pillars of the plantar arch, it operates, as Sir George
Humphry has pointed out, in the same manner as the
" tie-beam " of a roof. The transverse arch of the foot is
seen to best advantage across the line of the tarso-metatarsal
articulations.
312
THE LOWER LIMB
Dissection. — The muscles and tendons which have hitherto been only
partially detached from the bones of the foot should now be completely
removed and the ligaments defined.
Astragaloid Articulations. — The astragalus articulates by
means of the large posterior facet on the under surface of its
body with the corresponding posterior facet on the upper
surface of the os cal-
cis. Its head, on the
other hand, is re-
ceived into a large
socket which is
formed for it by the
sustentaculum tali of
the os calcis, the
scaphoid, and two
ligaments which pass
between the os calcis
and the scaphoid bone — viz., one
below, the inferior calcaneo-scaphoid,
and another on the outer side, the
external calcaneo-scaphoid ligament.
These two astragaloid articulations are
quite distinct, and each is provided
with a separate synovial membrane.
The ligaments which hold the
astragalus in its place are four in
number. Three are attached to
the os calcis and one to the scaphoid bone. They are :
Posterior surface of scaphoid
Inferior calcaneonavicular
ligament
External calcaneo-
navicular ligament
Facet on os calcis for
head of astragalus
Interosseous calcaneo-
astragaloid ligament
Facet on os calcis for
body of astragalus
Fig. ii8. — Astragalus re-
moved so as to show the
socket for its head.
i. An interosseous astragalo calcanean.
2. An external lateral astragalo-calcanean.
3. A posterior astragalo-calcanean.
4. A dorsal astragalo-navicular.
The interosseous ligament is by far the most powerful. It
occupies the tarsal canal, and consists of strong fibres
attached below to the groove between the articular facets on
the upper surface of the os calcis, and above to the correspond-
ing groove on the under surface of the astragalus.
The external ligament is a short band of fibres which pro-
ceeds from the outer surface of the astragalus to the outer
surface of the os calcis. It is parallel with the middle
fasciculus of the external lateral ligament of the ankle-joint,
»
ARTICULATIONS
j1 o
but it is placed on a deeper plane, and lies somewhat in
front of it.
The posterior ligament passes from the posterior border of
the astragalus to the os calcis. It closes the posterior
calcaneo-astragaloid articulation behind.
The dorsal astragalo -navicular ligament extends on the
dorsum of the foot from the head of the astragalus to the
scaphoid bone. It is thin and membranous.
The two lateral ligaments of the ankle-joint help to keep
the astragalus in its place.
Dissection. — The astragalus should now be removed by dividing the
various ligaments which hold it in place. By this proceeding the different
parts which form the socket for the head of the astragalus will be brought
into view ; and the posterior astragalo-calcanean articulation will be seen
to be completely cut oft from the anterior articulation by the interosseous
astragalo-calcanean ligament. The great strength of this ligament can
now be appreciated, and the facets on the head of the astragalus studied.
These are : — ( I ) a convex surface which looks forwards and articulates
with the scaphoid ; (2) an elongated facet on its under aspect (sometimes
divided into two), which rests upon the sustentaculum tali ; and (3)
between these, a triangular facet which corresponds with the upper surface
of the inferior calcaneo-scaphoid ligament. In the recent state (and indeed
usually also in the macerated condition of the bone) these three facets are
very distinctly mapped off from each other by intervening ridges.
Calcaneo- navicular Ligaments. — Although the os calcis
does not directly articulate with the scaphoid bone, it is
connected with it by two powerful and important ligaments,
viz., an inferior and an external.
The inferior calcaneo-scaphoid ligament is brought into view
by the removal of the astragalus. It fills up the angular gap
between the sustentaculum tali and the scaphoid bone,
and enters into the formation of the socket for the head
of the astragalus (Fig. 118). Its upper surface therefore is
smooth and covered with synovial membrane ; its lower
surface is supported by the tendon of the tibialis posticus.
This ligament has an important part to play in maintaining
the integrity of the longitudinal arch of the foot. Posteriorly
it is attached to the fore border of the sustentaculum tali,
whilst in front it is fixed to the under surface of the scaphoid
bone.
The external calcaneo-scaphoid ligament also forms a small
part of the socket for the head of the astragalus. It is placed
deeply in the anterior part of the depression between the os
calcis and the head of the astragalus. It is composed of
3J4
THE LOWER LIMB
short fibres which are attached in front to the outer side of
the scaphoid bone, and behind to the upper aspect of the
fore part of the os calcis, immediately to the outer side of
the facet on the sustentaculum tali (Fig. 118). An elon-
gated narrow facet may sometimes be noticed in corre-
Plantar inter-meta-
tarsal ligaments
Ridge on cuboid bone
Plantar cubo-cunei-
form ligament
Short plantar ligament
Tendon of peroneus
longus muscle
Long plantar ligament
Tendon of insertion of
peroneus longus muscle
Base of metatarsal bone
of hallux
Tendon of insertion
of tibialis anticus
muscle
Internal cuneiform bone
Plantar scapho-cunei-
form ligament
Tendon of tibialis
posticus muscle
Groove for tendon of
tibialis posticus muscle
\ Inferior calcaneo-
scaphoid ligament
Internal lateral or deltoid
ligament of ankle
Internal malleolus
Groove for tendon of flexor
longus hallucis muscle
Os calcis
Fig. 119. — Plantar Aspect of Tarsal and T^trso-metatarsal Joints.
spondence with this ligament, along the posterior and outer
margin of the articular surface of the head of the astragalus.
In such cases four facets mark the head of the astragalus —
one for each factor which enters into the formation of the
socket in which it lies.
Calcaneo-cuboid Articulation. — In this joint the concavo-
ARTICULATIONS 3 1 5
convex surface on the fore aspect of the os calcis articulates
with the corresponding surface on the posterior aspect of the
cuboid. It is a distinct joint, and is provided with a
separate synovial membrane. The ligaments which bind the
two bones together are : —
1. The inferior or plantar calcaneo-cuboid (long and short).
2. The dorsal calcaneo-cuboid.
3. The internal calcaneo-cuboid.
In the maintenance of the longitudinal arch of the foot
the plantar ligament has an importance which is surpassed
only by the inferior calcaneo-scaphoid ligament. It is dis-
posed in two layers which are respectively termed the long
and the short plantar ligaments, and which are separated
from each other by some fatty areolar tissue.
The superficial or long plantar ligament springs from the
under surface of the os calcis, in front of the internal and
external tuberosities, and extends forwards to the inferior
surface of the cuboid. Here it broadens out, and is for the
most part attached to the prominent ridge on the under
surface of that bone. Numerous strong fibres, however, are
prolonged forwards over the tendon of the peroneus longus
to find attachment to the bases of the three middle meta-
tarsal bones. The long plantar ligament therefore extends
over the greater part of the outer portion of the tarsus, and it
constitutes the longest of the tarsal ligaments. Further, it
forms the greater part of the sheath of the tendon of the
peroneus longus muscle.
The short plantar ligament is placed under cover of the long
plantar ligament. Slip the knife in between them, and carry
the cutting edge backwards so as to detach the long liga-
ment from the under surface of the os calcis. On throwing
the detached band forwards, the short plantar ligament comes
into view, and little dissection is required to make its connec-
tions apparent. It is composed of short but strong fibres,
not more than an inch in length. These spring from the
anterior tubercle on the under surface of the os calcis, and
are attached in front to the inferior aspect of the cuboid
behind its ridge. This ligament is broader than the long
plantar ligament, and is apparent along its inner border even
before the latter is reflected.
The dorsal and internal ligaments connect the os calcis and
Attached behind to the
316 THE LOWER LIMB
cuboid bones upon the superior and inner aspects of the
joint. The internal ligament, sometimes called interosseous, is
to be sought for in the deep pit between the head of the
astragalus and the fore part of the os calcis.
The joint between the astragalus and scaphoid bone, and that between
the os calcis and the cuboid bone, are sometimes referred to as the " trans-
verse tarsal joint." It is here that the movements of eversion and inversion
of the foot chiefly take place, and it should be noted that all the ligaments
which connect these two segments of the tarsus together, with the exception
of one, are attached posteriorly to the os calcis. They are-
Inferior calcaneo-scaphoid,
External calcaneo-scaphoid,
Long plantar,
Short plantar, os calcis.
Dorsal calcaneo-cuboid,
Internal calcaneo-cuboid, J
„ , . ... f Attached behind to the
Dorsal astragalo-scaphoid, ( astragalus.
Inter - cuneiform Articulations. — The three cuneiform
bones are held together so firmly that very little individual
movement is permitted. The chief uniting structures are
two strong i?iterosseous ligaments which pass between the non-
articular portions of their opposed surfaces. These can only
be seen when the bones are separated from each other.
Dorsal inter-cuneiform liga??ients are also present. These are
short flat transversely-placed bands.
Scapho - cuneiform Articulation. — The three cuneiform
bones articulate with the anterior surface of the scaphoid.
They are held in position by dorsal ligaments, which pass from
the dorsal surface of the scaphoid to the dorsal surface of each
of the cuneiform bones, and by plantar ligaments, which are
similarly disposed. The strength of the plantar ligaments is
greater than that of the dorsal ligaments, and they are very
largely formed by slips from the tendon of the tibialis posticus.
The dissector may now divide freely all the dorsal, and the innermost of
the plantar scapho-cuneiform ligaments. The scaphoid bone can then be
drawn backwards so as to expose the interior of the joint. The knife may
also be carried round the outer side of the external calcaneo-scaphoid
ligament. A much better view of this ligament is thus obtained, although
this dissection entails the division of the dorsal scapho-cuboid ligament.
The convex anterior articular surface of the scaphoid fits
into a transversely concave socket, which is formed for it by
the posterior surfaces of the three cuneiform bones, and often
by a small facet on the inner surface of the cuboid bone as
ARTICULATIONS 3 1 7
well. The articular surface of the scaphoid is divided by
prominent ridges into areas or facets corresponding with the
different parts of the socket in which it lies. The synovial
membrane which lines this joint is prolonged forwards into the
intercuneiform joints.
Scapho-cuboid and Cubo-cuneiform Articulations. — It has
been noted that the anterior pillar of the longitudinal arch of
the foot consists of an outer and an inner column. The
tarsal portions of these are connected together by the scapho-
cuboid and the cubo-cuneiform articulations.
It is only occasionally that the scaphoid bone touches and
articulates directly with the inner surface of the cuboid bone.
When it does so, the facet on the cuboid bone lies in series
with the articular surfaces on the hinder ends of the cunei-
form bones, and forms with them the socket for the anterior
surface of the scaphoid. The ligaments which bind the
scaphoid to the cuboid bone are disposed transversely, and
consist of — (1) a series of short strong interosseous fibres
which bind the opposed surfaces together : (2) a dorsal band ;
and (3) a plantar band.
The dorsal band has previously been divided in exposing
the interior of the scapho-cuneiform joint and in defining the
external calcaneo-scaphoid ligament, but the interosseous and
plantar ligaments may be readily displayed.
The cuboid, by an oval facet on its inner surface,
articulates with the external cuneiform bone, forming thereby
the cubo-cuneiform joint. The two bones are bound together
by interosseous, dorsal, and plantar ligaments. By dividing
the dorsal ligament and insinuating the knife between the
two bones the interosseous ligament may be detected. It is
the strongest of the three ligaments.
The synovial membrane which lines the scapho-cuneiform
articulation is prolonged into the cubo-cuneiform joint and
also into the scapho-cuboid joint when this exists.
Tarso-metatarsal Articulations. — The bases of the five
metatarsal bones articulate with the three cuneiform bones
and the cuboid bone, and are very firmly attached to them
by dorsal, plantar, and interosseous ligaments.
The dorsal ligaments are flat distinct bands which can
readily be defined. One such ligament passes to the base of
the first metatarsal from the internal cuneiform : three, one
from each of the cuneiform bones, proceed to the base of the
3i8 THE LOWER LIMB
second metatarsal ; one extends from the external cuneiform
to the base of the third metatarsal ; tivo, of which one pro-
ceeds from the external cuneiform, and the other from the
cuboid, go to the base of the fourth metatarsal ; and one
passes from the cuboid to the base of the fifth metatarsal.
The plantar ligaments are not so regularly disposed. Those
in connection with the first and second metatarsal bones are
very strong. Some of the bands have an oblique direction,
and those which go to the bases of the three middle meta-
tarsal bones are more or less connected with the sheath of
the tendon of the peroneus longus, and therefore with the
long plantar ligament.
To bring the interosseous ligaments into view, divide freely
the dorsal ligaments, and then forcibly bend the metatarsus
downwards upon the tarsus. The interosseous ligaments
will resist this proceeding, and on looking into the joints they
will be seen stretched and tense. If the force be continued
they will rupture. The interosseous ligaments are three in
number, viz., an internal, a middle, and an external.
The internal interosseous ligament is an exceedingly strong
band, which passes forwards and outwards from the anterior
part of the outer surface of the internal cuneiform bone to the
adjacent surface of the base of the second metatarsal bone.
The ?niddle interosseous ligament is small, and passes forwards
between the anterior part of the inner surface of the external
cuneiform and the adjacent surface of the base of the second
metatarsal. The external interosseous ligament passes from the
outer surface of the external cuneiform bone to the outer side
of the base of the third metatarsal. One interosseous liga-
ment therefore passes from the internal cuneiform bone and
two from the external cuneiform ; and of these, two are
attached to the base of the second, and the third to the base
of the third metatarsal bone.
Tars o- metatarsal Articular Surfaces. — The manner in
which the metatarsus is implanted upon the tarsus should
now be examined. The first metatarsal rests upon the
internal cuneiform, and this joint possesses a separate
synovial membrane. The second metatarsal rests upon the
middle cuneiform, but its base is grasped by the projecting
anterior ends of the internal and external cuneiform bones,
with both of which it articulates, and with both of which it
is connected by interosseous ligaments. No wonder then
ARTICULATIONS 3 1 9
that this metatarsal should possess so little power of inde-
pendent movement, and present a difficulty to the surgeon
when he is called upon to amputate the fore -part of the foot
through the tarso-metatarsal articulation. The third ?neta-
tarsal rests upon the external cuneiform. The synovial
membrane which lines the joints between the tarsus and
the second and third metatarsal bones is continuous
with that which is present between the internal and
middle cuneiform bones, and through this with the scapho-
cuneiform synovial membrane. The bases of the fourth and
fifth metatarsal bones are supported by the cuboid, but that
of the fourth, by its inner margin, articulates also with the
external cuneiform. A separate synovial membrane is present
in the articulation between the two outer metatarsal bones
and the tarsus.
Intermetatarsal Joints. — The bases of the metatarsal
bones, with the exception of the first, articulate with each
other, and are very firmly bound together.
The ligaments which connect the bases of the four outer
metatarsal bones are dorsal, plantar, and interosseous. To
bring the interosseous ligaments into view it is necessary to
divide the dorsal ligaments, and then forcibly separate the
bases of the bones from each other. They are strong bands
which pass between the non-articular portions of the basal
parts of the bones. They constitute the chief bonds of
union.
In addition to these basal ligaments, the strong transverse
metatarsal ligament unites the distal extremities of the meta-
tarsal bones. This ligament has been previously described
(p. 288).
Synovial Cavities of the Foot. — There are six separate
synovial cavities in connection with the tarsal, tarso-meta-
tarsal, and intermetatarsal articulations, viz. — (1) in the joint
between the posterior facets of the astragalus and os calcis ;
(2) in the calcaneo-cuboid joint; (3) in the joint formed by
the head of the astragalus, the scaphoid, the sustentaculum
tali, and the two calcaneo-scaphoid ligaments; (4) a com-
plicated synovial membrane which lines the scapho-cuneiform
articulations, and is prolonged forwards between the cunei-
forms, and also between the cuboid and external cuneiform
bones. This synovial membrane, however, is not confined
to the tarsus, but reaches forwards into the articulation
32o THE LOWER LIMB
between the second and third metatarsal bones and the
tarsus, as well as into the joints between the bases of the
second, third, and fourth metatarsal bones:1 (5) a separate
synovial lining for the joint between the first metatarsal and
the internal cuneiform: (6) a distinct synovial membrane for
the articulations between the cuboid and the two outer meta-
tarsal bones. This is prolonged forwards into the joint
between the bases of these two metatarsals.
Metatarso-phalangeal and Interphalangeal Joints. — These
joints are constructed upon a plan almost identical with that
of the corresponding joints of the upper extremity. For the
detailed description the student is therefore referred to p.
288. In the metatarso-phalangeal joint of the great toe the
thick inferior ligament ox fibrous plate holds two large sesamoid
bones, which slide upon grooved surfaces on the head of the
metatarsal bone.
Movements. — The movements which take place in the tarsometatarsal,
intermetatarsal, and in the majority of the tarsal joints, are of a gliding
character. In the joints between the astragalus and scaphoid, and also
between the os calcis and the cuboid, movements of a wider range are
possible. It is here that the movements of inversion and eversion of the
foot chiefly take place.
The first and the fifth metatarsal bones enjoy a considerable degree of
mobility. The second metatarsal is so tightly grasped by the internal and
external cuneiform bones, and so firmly bound to the tarsus by its basal
ligaments, that only a slight degree of movement is possible.
At the metatarso-phalangeal joints, flexion, extension, abduction, and
adduction are allowed : whilst the inter-phalangeal joints only permit of
flexion and extension.
In the erect posture the parts of the foot which are chiefly concerned in
transmitting the weight of the body to the ground are the heel, the head of
the first metatarsal bone, and the shaft of the fifth metatarsal bone. Rather
more than the middle third of the inner border of the foot is raised above
the ground. The outer border of the foot is more or less in contact with
the ground in its entire extent, whilst the tips of the toes rest lightly on the
ground. In walking — (it the heel is brought down ; (2) the sole and toes
follow ; (31 the heel is raised, and the weight of the body is transferred to
the heads of the metatarsal bones and the toes. In the second and third
parts of this operation the arches of the foot are flattened to a certain extent,
but more especially in the third part of the process is the transverse arch
spread out. Great elasticity is thus given to the step.
The muscles which are chiefly concerned in producing eversion of the
foot are the three peroneal muscles ; those which operate as invertors of the
foot are the tibialis anticus and the tibialis posticus.
1 The external interosseous tarso-metatarsal ligament, which passes from
the external cuneiform bone (frequently from the cuboid bone) to the base of
the third metatarsal bone, separates the articulations of the fourth and fifth
metatarsal bones from the general tarsal articular cavity.
ARTICULATIONS 321
The extensors of the toes are the extensor longus hallucis, the extensor
brevis digitorum, and the extensor longus digitorum. The lumbrical
muscles, and the interosseous muscles, through their insertions into the
extensor tendons of the four outer toes, operate as extensors of the second
and third phalanges.
The flexors of the proximal phalanges are the lumbricales, interossei,
flexor brevis hallucis, and flexor brevis minimi digiti. The flexor of the
second phalanges is the flexor brevis digitorum : whilst the flexors of the
distal phalanges are the flexor longus digitorum, the musculus accessorius,
and the flexor longus hallucis.
Abduction and adduction of the toes at the metatarsophalangeal joints
are produced by the interosseous muscles, the abductor hallucis, the
adductor obliquus hallucis, the adductor transversus hallucis, and the
abductor minimi digiti. The movements of abduction and adduction take
place with reference to a line drawn through the second toe.
VOL. I 21
322 ABDOMEN
ABDOMEN.
When the body is brought into the dissecting-room, it is first
placed in the lithotomy position (Fig. 121). The body is
retained for two days in this posture, and during this time
the dissector of the abdomen is expected to dissect the
perineum.
MALE PERINEUM.
Boundaries of the Perineum. — The perineal space may be
said to correspond to the inferior aperture or outlet of the
pelvis. It is necessary, then, that the student should renew
his acquaintance with this part of the skeleton before he
begins the dissection. Let him obtain a pelvis with the liga-
ments in situ. He will observe that he has to deal with
a diamond-shaped space, and that it has the following
boundaries : in front, the symphysis pubis and the sub-
pubic ligament ; behifid, the coccyx ; and on each side from
before backwards, the rami of the pubis and ischium, the
tuberosity of the ischium, and the great sacro-sciatic ligament.
If he now turn his attention to the subject before him he
can readily identify these limits. The great sacro-sciatic liga-
ment, however, is somewhat obscured, from its being covered
by the gluteus maximus muscle, but it can be felt by pressing
deeply in a line between the ischial tuberosity and the coccyx.
In the undissected body the superficial area of the perineum
is very limited ; indeed, when the limbs are extended and
approximated (as is the case when one stands erect), it merely
consists of a narrow groove running forwards between the
thighs from the coccyx towards the pubis. In this groove
are placed the anus or orifice of the rectum and the roots ot
the scrotum and penis, whilst in the middle line a cutaneous
ridge — the median raphe — may be observed. This raphe can
be traced from the anus forwards over the scrotum and along
the under surface of the penis.
Subdivision of the Space. — The perineal space has, there-
fore, a diamond-shaped form, and it is customary to subdivide
MALE PERINEUM
323
it arbitrarily into two portions by drawing an imaginary
transverse line between the anterior parts of the ischial
tuberosities immediately in front of the anus. Two triangles
are thus mapped out. The anterior of these may be appro-
priately called the urogenital triangle, because the most im-
portant objects which it contains are the urethra and the root
of the penis ; the posterior may be distinguished as the rectal
triangle, from its containing the lower end of the rectum.
FlG. i 20. — Outlet of Male Pelvis.
Preparation of Part for Dissection. — To prepare the part for dissection,
a staff should first be introduced into the bladder. The dissector must
stand upon the left side of the subject. Having smeared the instrument
with oil, hold it lightly in the right hand and guide it gently along the
upper and right wall of the urethra. When the point of the instrument
reaches the triangular ligament, — a strong aponeurotic structure which is
stretched tightly across the pubic arch — depress the handle, but use no
force. Should any difficulty be experienced, introduce the forefinger of the
left hand into the rectum to guide the point of the instrument along the
membranous and prostatic portions of the urethra. The most dependent
part of the scrotum should now be stitched to the prepuce of the penis, and
dragging both penis and scrotum forwards upon the staff, they should be
fixed by means of the twine to its handle. Lastly, fasten the handle of the
staff to the cord which passes behind the flexed knee-joints of the subject.
The rectum should then be moderately distended with tow, and the
orifice of the anus stitched up.
Reflection of Skin. — Two incisions are required : — (Fig. 121) (1) a
transverse incision along the line which separates the rectal from the
urogenital triangle — i.e. , in front of the tuberosities of the ischium ; (2) an
324
ABDOMEN
incision at right angles to this in the line of the median raphe. This
incision should begin well forwards on the scrotum and be continued back
a little beyond the point of the coccyx. At the anus the knife should be
carried round it so as to encircle it.
The four triangular flaps which are marked out should now be reflected
close to the anal orifice. Some difficulty will be experienced in raising the
skin. This is due to the presence of a number of fasciculi of involuntary
muscle which radiate outwards from the opening. The term corrugator
cutis ani is applied to this muscle. The superficial fascia and the external
sphincter mtiscle are now exposed.
Fig. 121.
Superficial Fascia. — The student should examine the
superficial fascia as it is spread over the entire extent of the
perineal space. It shows great differences in character and
texture in different positions. At the side of the anus it is
remarkable for the large quantity of fat it holds in its meshes.
This fat is soft and lobulated, and passes upwards upon each
side of the rectum in the form of a pliable and elastic pad.
Over the tuberosities of the ischium the superficial fascia
undergoes a striking alteration. Here it becomes tough and
stringy ; dense fibrous septa separate the lobules of fat from
each other and connect the skin with the subjacent bone.
MALE PERINEUM 325
Make a deep incision into it with the knife, and a bursa
will be displayed intervening between the fascia and bone.
This bursal sac is frequently intersected by strong fibrous
bands or cords. In this locality the superficial fascia acts
as a cushion on which the tuber ischii rests when the body
is in the sitting posture.
But, again, if the superficial fascia be now followed forwards
over the urogenital triangle, another change in its character
becomes manifest. The farther forwards we proceed, the
scarcer becomes the fat which it contains in its meshes, and in
the scrotum the fat entirely disappears and gives place to a
thin layer of involuntary muscular fibres. These constitute
the dartos muscle, and are recognised by their ruddy colour.
The rugosity of the scrotal integument is caused by the
contraction of these fibres.
Over the urogenital triangle the superficial fascia can be
shown to consist of two very definite layers. The superficial
layer is fatty and is not confined to this region. In fact, it is
simply a portion of the general fatty covering of the body.
Behind, it is continuous with the plugs of fat which fill up
the ischio- rectal fossa; on either side, it leaves the perineum
and becomes continuous with the fatty tissue on the inner
aspects of the thighs. The deep layer is of an altogether
different nature. It is a dense membranaceous stratum, devoid
of fat, which is spread over the urogenital triangle. It is
called the fascia of Colles. This sheet of fascia forms very
definite attachments around the limits of the urogenital triangle.
Thus, on either side it is fixed to the anterior lips of the
rami of the pubis and ischium, whilst inferiorly it is tucked
round the two transverse perineal muscles and blends with
the base of the triangular ligament. A pouch is thus formed,
which is bounded in front by the fascia of Colles, behind by
the triangular ligament, laterally by the attachment of these
to the sides of the pubic arch, whilst below, it is closed by
the union of the fascia of Colles with the base of the triangular
ligament (Fig. 123, p. 330). Within this pouch certain im-
portant parts are placed — viz., the superficial perineal muscles,
vessels, and nerves, the long pudendal nerves, the bulb and
crura of the penis, and the termination of the pudic artery.
It is partially divided into two lateral parts by a median
septum, which dips backwards from the superficial fascia.
This septum is very perfect posteriorly, but becomes incomplete
326 ABDOMEN
towards the scrotum. Traced forwards, the fascia of Colles
passes over the scrotum, penis, and spermatic cords, to the
front of the abdomen, where it becomes continuous with the
fascia of Scarpa.
How to verify these facts. — The student can verify these facts in two
ways, viz. — (i) by inflating the pouch with air, and (2) by dissection.
Make a longitudinal incision, large enough to admit the nozzle of the
bellows (or better still an injection pipe fitted to a bicycle-pump), into the
superficial fascia towards the back part of the pouch and a little to one side
of the middle line. This cut must be carried through the fascia until the
fibres of the superficial perineal muscles are exposed. In using the pump
the margins of the opening into the pouch must be held tightly around the
nozzle of the pipe. The air which is introduced passes forwards, and is
first confined to one side of the pouch. Reaching the scrotum, however,
where the septum is incomplete, it forces its way across the middle line,
and inflates the opposite side of the pouch. The pouch is now rendered
prominent, and the attachments of the fascia become very evident. The
air cannot pass into the rectal triangle owing to the union of the fascia of
Colles to the base of the triangular ligament ; it cannot pass down the inner
aspect of the thighs from the attachment of the fascia to the sides of the
pubic arch ; it can only force its way forwards under the superficial fascia
and dartos muscle of the scrotum, and from this on to the penis and along
the spermatic cords to the anterior aspect of the abdomen. By this means
the dissector obtains a very striking view of the course which would be
taken by urine escaping from a rupture in the urethra in front of the
triangular ligament.
The attachments of the fascia of Colles are so important that the student
should also test them by dissection. To do this it is necessary to make
two incisions through the superficial fascia. Enter the knife in the middle
line at the root of the scrotum, and carry it backwards and outwards to the
tuber ischii on each side of the body. A central /\-snaPed flap and two
lateral flaps of fascia are thus marked out. By raising and turning back-
wards the central portion, the septum of the pouch is brought into view,
and the attachment of the fascia to the base of the triangular ligament is
demonstrated, and by throwing each lateral flap outwards it will be seen
to be firmly fixed to the side of the pubic arch. In effecting this dissection
the utmost care is demanded on the part of the student. In the areolar
tissue immediately subjacent to the superficial fascia are the superficial
perineal vessels and nerves, which are certain to be injured, or perhaps even
reflected with the fascia, unless the greatest caution be exercised.
Rectal Triangle.
The dissection of this portion of the perineal space will
disclose the following parts : —
1. The external sphincter ani muscle.
2. The lower part of the rectum covered by the levator ani muscle and
the anal fascia.
3. The parietal or obturator layer of pelvic fascia.
4. The lower border of the gluteus maximus muscle and the great
sacro-sciatic ligament.
5. The coccygeus muscle.
1
MALE PERINEUM
327
6. The inferior hemorrhoidal vessels and nerve.
7. The perineal branch of the fourth sacral nerve.
8. The commencement of the two superficial perineal nerves.
9. The perforating cutaneous branch of the fourth sacral nerve.
Sphincter Ani Externus. — When this muscle is cleaned it
will be seen to consist of a thick ring of muscular fibres
surrounding the orifice of the rectum. Behind, it is attached
by a pointed tendon to the tip and posterior surface of the
terminal part of the coccyx ; in front, it blends with other
perineal muscles in the
central point of the peri-
neum. The fibres, in
passing between these
two points of attachment,
encircle the anal orifice
and constitute a true
sphincter muscle. Some
of the superficial fibres,
both in front and behind
the anal opening, are
directly attached to the
skin. It draws its nervous
supply from two sources,
viz., the fourth sacral
?ierve and the inferior
hemorrhoidal ?ierve.
Ischio-rectal Fossa. —
Although the rectum is
the largest and most
important object which
is contained within the
posterior portion of the
perineum, it does not fill up the entire extent of the rectal
triangle. An interval or recess is left upon each side of the
rectum — between it and the ischium, — and to this recess
is given the name of the ischio-rectal fossa.
In shape the ischio-rectal fossa is pyramidal, the apex of
the pyramid being directed upwards towards the pelvic cavity,
and the base downwards towards the integuments. The
inner wall of the space is sloping, whilst the outer wall is steep
and perpendicular.
Boundaries. — Whilst the term "ischio-rectal" is applied to
1—21 a
Fascia iliaca
Peritoneum
>L Bladder
Obturator
internus
Vesicula
seminalis
Levator ani
Pudic vessels
and nerve
Rectum
Fig. 122. — Diagram. The arrow is directed
upwards into the ischio-rectal fossa. The
parietal pelvic fascia is seen upon the
inner surface of the obturator internus.
Observe also the anal fascia clothing the
outer surface of the levator ani and the
rectal fascia upon its inner surface.
328 ABDOMEN*
this fossa, it must be borne in mind that neither the ischium
nor the rectum enters directly into the formation of its walls.
Both are separated from the space by fascial and muscular
layers. Upon the inner aspect of the ischium is the obturator
internus muscle, and this again is covered by the parietal or
obturator layer of the pelvic fascia as it is continued down
to be attached to the tuberosity of the ischium and the great
sacro -sciatic ligament. On the other hand, the rectum is
clothed from without inwards by — (i) the anal fascia, a thin
aponeurotic membrane which invests the outer surface of the
levator ani; (2) by the levator ani muscle; and (3) by the
rectal portion of the visceral layer of the pelvic fascia — a thin
layer of fascia which covers that part of the inner surface of
the levator ani which is applied to the rectum (Fig. 122).
Strictly speaking, therefore, the perpendicular outer or ischial
wall of the fossa is formed by the parietal layer of the pelvic
fascia, and the sloping inner or rectal wall by the anal fascia.
In front, the space is limited by the triangular ligament —
whilst behind, it is bounded by the posterior or lower margin
of the gluteus maximus and the great sacro-sciatic ligament.
Contents. — The ischio-rectal fossa is completely rilled up
by a mass of fat which is prolonged upwards into it from the
superficial fascia. The soft, pliable nature of this fat readily
allows of the distension of the rectum. Embedded in its midst
are certain blood-vessels and nerves. Crossing the fossa from
its outer to its inner wall are the inferior hemorrhoidal vessels
and nerve ; entering the fossa at its posterior part is the
perineal branch of the fourth sacral nerve ; turning round the
lower border of the gluteus maximus, not far from the coccyx,
is the perforating cutaneous bra?ich of the fourth sacral nerve ;
whilst in the anterior part of the space will be found the
commencement of the two superficial perineal fierves (Fig. 123).
Dissection. — Begin by exposing the posterior margin of the gluteus
maximus muscle. Take a point a short distance to the outside of the tuber
ischii and another in the middle line about an inch above the tip of the
coccyx, and cut boldly down through the superficial fascia, in a line
between these points, until the fleshy fibres become visible. Winding
round the lower margin of the muscle so as to gain its superficial aspect,
there are a few small arteries and nerves. The arteries are derived from
the inferior /hemorrhoidal vessels, or from the sciatic artery, whilst the
nerves are the perforating cutaneous branch from the fourth sacral nerve
and some offsets from the small sciatic nerve. Both are destined for the
supply of the skin on the lower part of the gluteal region. The perforating
cutaneous nerve turns round the margin of the gluteus maximus close to
MALE PERINEUM 329
the coccyx, whilst the cutaneous branches from the small sciatic nerve
appear on the outer side of the tuber ischii. Having secured these vessels
and nerves, clean the lower margin of the gluteus maximus, and then
proceed to dissect the ischio- rectal fossa. If the subject is obese, a
considerable quantity of fat may be removed at once without endangering
the inferior hemorrhoidal vessels and nerve. Take the surface of the
gluteus maximus and the margin of the external sphincter as guides, and
transfix the fat with the knife in this plane. The adipose tissue superficial
to this plane may be removed en masse with safety. The hcemorrhoidal
vessels and nerve may be found by dissecting cautiously in the fat and
carrying the knife in a transverse direction from the outer to the inner wall
of the space. The branch from the fourth sacral nerve appears by the side
of the coccyx.
Roof of the Space. — When the contents of the space are
secured, continue to remove the fat from the fossa until its
walls are fully displayed. On passing the finger upwards, its
passage into the pelvis is prevented by the junction of the
anal fascia with the parietal or obturator layer of the pelvic
fascia (Fig. 122, p. 327). Further, if the anal fascia be
removed, its entrance into the pelvis is still resisted by the
visceral layer of the pelvic fascia, which at this level passes
inwards from the parietal pelvic fascia, and also by the levator
ani muscle, which lies on the lower surface of the visceral
pelvic fascia.
Internal Pudic Vessels and Nerve. — The dissector should
now pass his finger upwards and downwards over the surface
of the parietal or obturator layer of the pelvic fascia, which
covers the obturator internus muscle and forms the outer
wall of the ischio-rectal fossa. About an inch and a half
above the lower border of the ischial tuberosity he will feel
very distinctly the pudic vessels and nerve as they pass for-
wards to gain the urethral triangle. In this position they
are enclosed in a tube or sheath formed by the parietal pelvic
fascia. This fascial tunnel is called Alcock's canal. The
student must for the present be satisfied with this partial view
of these structures. To expose them would necessitate the
division of the parietal pelvic fascia, and this should be kept
entire until the pelvic fascia can be studied as a whole.
Inferior Hsemorrhoidal Vessels (arteria haemorrhoidalis
inferior). — The inferior hemorrhoidal arteries are branches of
the internal pudic. They are usually two or three in number,
and, piercing the inner wall of Alcock's canal, they pass
inwards through the fat of the ischio-rectal fossa to supply the
lower end of the rectum and the muscles in connection with
it, as well as the skin around the anus. They anastomose
33°
ABDOMEN
with the corresponding arteries of the opposite side and
with branches from the middle and superior hemorrhoidal
Inferior hemorrhoidal nerve
Inferior hemorrhoidal artery
Fig. 123.— Dissection of the Perineum. The Scrotum and the Penis
have been cut transversely across and removed.
arteries. They likewise send a few twigs round the lower
border of the gluteus maximus, in company with the perforat-
ing cutaneous nerve to supply the skin in the lower part of
the buttock.
MALE PERINEUM 331
Inferior Hemorrhoidal Nerve. — This nerve accompanies
the vessels of the same name. It may proceed directly from
the sacral plexus, but more frequently it is a branch of the
internal pudic nerve. Perforating the inner wall of Alcock's
canal, it enters the ischio-rectal fossa, and then it breaks up
into muscular, cutaneous, and communicating branches. The
muscular twigs supply the external sphincter : the cutaneous
offsets are given to the skin which surrounds the anus, while
the communicating filaments pass forwards to join the long
pudendal nerve and the superficial perineal nerves.
Perineal Branch of Fourth Sacral Nerve. — This small
nerve enters the ischio-rectal fossa by piercing the coccygeus
muscle at the side of the coccyx. It is distributed to
the skin between the anus and coccyx, and to the external
sphincter muscle.
Ano-coccygeal Body.— An indefinite mass of muscular and
fibrous tissue which lies between the tip of the coccyx and
the anus receives the name of ano-coccygeal body. It is best
seen in sections through the pelvis, and it requires notice on
account of the support which it gives to the rectum in front
of the coccyx. The muscular tissue which enters into its
constitution belongs to the levator ani and the external and
internal sphincter muscles (Symington).
Urogenital Triangle.
The superficial fascia in this locality has already been
studied. The following is a list of the structures which still
require to be examined : —
1. The superficial perineal vessels and nerves.
2. The long pudendal nerve.
3. The root of the penis \ The bulb and the crura.
( a. Transversus perinei.
4. The superficial perineal muscles. •! b. Ejaculator urince.
\ ■:. Erector penis.
5. The triangular ligament.
6. The internal pudic vessels and nerve and their branches.
7. The compressor urethra? muscle.
8. Cowpers glands.
9. The membranous portion of the urethra.
10. The deep layer of the triangular ligament (i.e., the parietal pelvic
fascia opposite the pubic arch).
Superficial Perineal Vessels and Nerves. — The superficial
332 ABDOMEN
perineal vessels and nerves must now be followed out.
There are two arteries and three nerves to be looked for : —
. . / I. Superficial perineal artery.
[2. Transverse perineal artery.
( I. Posterior or external superficial perineal nerve.
Nerves. -| 2. Anterior. or internal superficial perineal nerve.
^ 3. The long pudendal nerve or the nerve of Soemm erring.
The superficial perineal artery, a branch of the pudic, first
pierces the inner wall of Alcock's canal, and then the base
of the triangular ligament, so as to gain the interior of the
perineal pouch of fascia. It now crosses the transversus
perinei muscle, and is continued forwards in the interval
between the ejaculator urinse and erector penis to the
scrotum, to the dartos muscle and integuments of which it is
distributed in the form of numerous long, slender branches.
Before it reaches the scrotum, it supplies twigs to the super-
ficial perineal muscles. It is accompanied by the superficial
perineal nerves.
The transverse perineal artery is a small vessel which usually
springs from the pudic by a common root of origin with the
preceding. It pierces the base of the triangular ligament,
and, gaining the surface of the transversus perinei muscle,
proceeds transversely inwards to the interval between the
rectum and the bulb, where it ends by supplying the parts
in this locality, and by anastomosing with the corresponding
vessel of the opposite side.
The posterior superficial perineal nerve, a branch of the
perineal division of the pudic nerve, has already been seen in
the anterior part of the ischio-rectal fossa, where it effects
a communication with the inferior hemorrhoidal nerve. It
leaves the fossa by piercing the base of the triangular liga-
ment, and is continued forwards with the superficial perineal
artery to the scrotum.
The anterior superficial perineal nerve, also derived from the
perineal part of the pudic nerve, supplies a few twigs to the
levator ani, and, piercing the base of the triangular ligament,
is prolonged forward with the posterior nerve to the scrotum.
In some instances this nerve passes under cover of the trans-
versus perinei muscle.
Dissection. — Instead of searching for the long pudendal nerve at the
point where it becomes superficial, and then following it towards its
distribution, it is much easier to find it after it has entered the perineal
MALE PERINEUM
333
pouch of fascia. Here it will be discovered lying in close relation to the
two preceding nerves, but to their outer side. Trace it forwards and
backwards. The long pudendal communicates with the inferior hemor-
rhoidal nerve, and also with the posterior superficial perineal nerve.
The long pudendal ?ierve is derived from an altogether
different source. It is a branch of the small sciatic nerve,
and pierces the deep fascia of the thigh a short distance in
front of the tuber ischii, and about an inch and a half to the
outer side of the margin of the pubic arch. As it proceeds
forwards it inclines inwards, and, piercing the attachment of
the superficial fascia to the margin of the pubic arch, it
accompanies the other vessels and nerves to the scrotum, the
outer and front part of which it supplies.
Dissection. — Divide the superficial perineal vessels and nerves, and
throw them aside.
Root of the Penis. —
tion the student should con-
sider the position of the
triangular ligament, and the
relation which it bears to
the root of the penis. The
triangular ligament is a
strong aponeurotic mem-
brane which stretches across
the pubic arch, and sub-
divides the urogenital por-
tion of the perineum into a
superficial and a deep area.
The root of the penis is placed
altogether in front of it, in
At this
stage
of the dissec-
Dorsal
artery
J-
Dorsal
vein
/ Dorsal nerve
Corpus
spongiosum
Urethra
Fig. 124. — Transverse section through
the body of the Penis.
the superficial area of this
region. With the handle of the knife clear away for a short
distance the loose tissue which surrounds the body of the
penis. The body of the penis is then seen to consist of three
cylindrical masses which are chiefly composed of erectile tissue,
and are placed in close apposition with each other. . These
are the two corpora cavernosa and the corpus spongiosum.
The corpora cavernosa constitute the chief bulk of the
organ. They are placed side by side and form the dorsum
and sides of the penis. They are partially blended with each
other along the middle line, — indeed, the only surface indica-
tion of the double nature of this portion of the penis are two
334
ABDOMEN
median longitudinal grooves which run one along its upper
and the other along its lower aspect. The corpus spongiosum
is slender in comparison with the corpora cavernosa, and is
lodged in the groove which extends along the lower aspect
of these bodies. On account of this, the body of the penis
has a somewhat prismatic form. The corpus spongiosum is
traversed throughout its whole length by the urethra.
If these three constituents of the body of the penis be
traced backwards, the student will observe that opposite the
Corpus cavernosum
Corpus spongiosum
Triangular
ligament
Transversus
perinei
Ischial
tuberosity
Fig. 125. — The Root of the Penis and the Triangular Ligament
(formalin specimen).
lower part of the symphysis pubis they separate from each
other and become attached to parts in the superficial area of
the urogenital triangle. The corpora cavernosa diverge widely
from each other, and now they receive the name of the crura
of the penis. Each crus is fixed firmly to the corresponding
side of the pubic arch by an attachment which extends from
the sub-pubic ligament backwards to a point a short distance
in front of the tuberosity of the ischium. Close to the point
where it becomes continuous with the corresponding corpus
cavernosum it shows a slight dilatation or bulging ; from this
MALE PERINEUM
335
to its posterior extremity it gradually tapers away. The corpus
spongiosum is continued backwards in the middle line of the
body to within a short distance of the anus, and it expands
so as to form a bulbous posterior extremity. The corpus
spongiosum, as it lies in the interval between the diverging
crura, is therefore termed the bulb of the penis. The bulb
rests upon the superficial aspect of the triangular ligament,
Corpus cavernosum
Crus penis : surface at-
tached to the pubic arch
Urethra (divided)
Erectile tissue
of bulb
Bulb of corpus spongiosum
Fascia covering bulb divided where
it is continuous with the triangular
ligament
Fig. 126. — Dorsal or attached aspect of the Penis. The specimen was
hardened by formalin injection and removed from the pubic arch and the
triangular ligament.
and it is firmly bound down to this by an aponeurotic
investment, which is prolonged over it from the ligament.
The posterior extremity of the bulb is frequently notched
in the middle line — an indication of its originally double
constitution.
The bulb and the two crura together constitute the root of
the penis, and each is provided with a special muscle, which
at present hides it from view. Clothing the bulb the student
will recognise a bipenniform muscle called the ejaculator
urince, whilst moulded upon the surface of each crus is the
336 ABDOMEN
erector penis muscle. These muscles should now be cleaned
and their connections examined.
Superficial Perineal Muscles. — Under this heading are
included not only the ejaculator urinse and erector penis
muscles, but also the transversus perinei. The superficial
perineal muscles have been seen to lie within the pouch
formed by the superficial fascia and the triangular ligament.
When the superficial fascia is removed each will be found to
be invested by its own delicate aponeurotic layer.
Transversus Perinei (musculus transversus perinei super-
ficialis). — This muscle is a narrow slip of muscular fibres
which arises from the inner aspect of the ascending ramus of
the ischium close to the tuberosity. It passes inwards and
unites with the corresponding muscle of the opposite side in
the central point of the perineum.
The central point of the perinemn is a tendinous septum
situated in the middle line of the body close to the posterior
end of the bulb and a short distance in front of the anus.
Towards this point, a number of the perineal muscles converge
to obtain attachment. On each side, it gives attachment to
the transverse perineal muscles ; behind, to the sphincter ani ;
in front, to the posterior fibres of the ejaculator urinae ; whilst
from above, the anterior fibres of the levator ani descend to
reach its upper aspect.
Ejaculator Urinae (musculus bulbo-cavernosus). — This
muscle is spread over the bulb and posterior part of the
corpus spongiosum. It is composed of two symmetrical
halves, and its fibres take origin from the central point of
the perineum and from a fibrous median raphe which is
prolonged forwards between the two halves of the muscle.
The insertion differs according to the point at which the
muscle is examined. The posterior fibres are simply attached
to the superficial aspect of the triangular ligament ; the
?niddle fibres, constituting the greater part of the muscle,
sweep around the corpus spongiosum so as to invest it com-
pletely, and are inserted into a common aponeurosis upon the
upper surface of this portion of the penis ; lastly, the anterior
fibres form two long narrow muscular bands which diverge
from each other like the limbs of the letter V? and, passing
forwards over the sides of the corpora cavernosa, are inserted
into an aponeurosis on the dorsum of the penis. Thus the
posterior fibres partially embrace the bulb ; the middle fibres
MALE PERINEUM 337
embrace the corpus spongiosum ; whilst the anterior fibres
embrace the body of the penis. The ejaculator urinae sup-
ports the urethra during micturition, and by its contraction
it ejects the last drops of urine or semen from the passage.
Erector Penis (musculus ischio-cavernosus). — The erector
penis lies upon the cms penis. It arises by fleshy fibres from
the inner aspect of the tuber ischii, and is inserted by an
aponeurotic expansion into the lower and outer surface of the
anterior portion of the crus.
Perineal Nerve. — -This is one of the two terminal branches
of the pudic nerve. It supplies twigs to the skin, to the
muscles of the perineum, and to the bulb of the penis. The
cutaneous branches have already been followed out. They
are the posterior and anterior superficial perineal nerves.
Muscular twigs, occupying a deeper plane, may be traced to
each of the three superficial perineal muscles and to the
levator ani, whilst a few minute offsets pierce the triangular
ligament to supply the compressor urethrae muscle. The
nerve to the bulb is a small branch which breaks up into fila-
ments which enter the hinder part of the corpus spongiosum.
Perineal Triangle. — If the superficial perineal muscles be
now examined in regard to the relations which they hold to
each other, the student will observe that they constitute the
boundaries of a small triangular space upon each side of
the middle line. The base of the triangle is formed by the
transversus perinei ; externally it is limited by the erector
penis, and internally by the ejaculator urinae. Let the
student now place the point of his finger within this space
and press upwards and backwards. He will perceive that it
rests upon a strong resisting membrane. This is the tri-
angular ligament, which therefore forms the floor of the space.
Dissection. — To bring the triangular ligament of the urethra fully into
view, it is necessary in the first place to remove the superficial perineal
muscles. When this is done the three divisions of the root of the penis are
exposed to view, and their manner of attachment (which has already been
described, p. 334) can be studied. Detach in the next place the crura
penis from the sides of the pubic arch, and turn them aside. This must
be effected with care, so as not to destroy the attachment of the ligament
to the sides of the pubic arch, or to injure the pudic artery and dorsal nerve
of the penis, which pierce the ligament in its upper part.
Triangular Ligament. — This is now seen to be a strong
aponeurotic membrane which stretches across the pubic arch.
It must be regarded as lying in the same morphological plane
vol. 1 — 22
33*
ABDOMEN
as the bony and ligamentous wall of the pelvis, and as
completing the pelvic wall in front in the same manner as
the thyroid membrane fills up the gap formed by the thyroid
foramen.
Upon each side the triangular ligament is attached to the
margins of the rami of the pubis and ischium. Its base is
somewhat indefinite, and has already been seen to blend
along the lower border of the transversus perinei muscle
Dorsal vein of penis
Dorsal artery and nerve of
the penis
Artery to corpus cavernosum
Transverse ligament of
perineum
Internal pudic artery
Urethra
Cowper's gland
Compressor
urethra;
Artery to bulb
Fig. 127. — Deep dissection of the Perineum. The penis has been removed,
the urethra cut across, and the superficial layer of the triangular ligament
removed on the left side.
with the fascia of Colies. In addition to this attachment,
however, a careful dissection in a good subject will show that
the central part of the base projects backwards and downwards
in the form of a short process or peak, which joins the
central point of the perineum. Near the symphysis pubis
some transverse fibres, in association with the triangular
ligament, pass from one side of the pubic arch to the other,
and form a more or less distinct band, called the transverse
perineal liga??ient. Between the upper border of this band
and the sub-pubic ligament an oval gap is left for the passage
of the dorsal vein of the penis.
.1
MALE PERINEUM 339
In the erect posture of the body the superficial surface of
the triangular ligament looks downwards and forwards, whilst
its deep surface looks upwards and backwards towards the
cavity of the pelvis. In close contact with its superficial
surface are the parts which constitute the root of the penis,
viz., the bulb and the two crura and the muscles which are
associated with them, also the transversus perinei muscle on
each side. The structures which are in relation to its deep
surface will be studied when it is reflected.
The triangular ligament is not an unbroken continuous
layer of fascia. It is pierced — (1) by the urethra ; (2) by the
internal pudic arteries \ (3) by the dorsal nerves of the penis ;
(4) by the arteries to the bulb ; (5) and lastly, at its base, where
it blends with the superficial fascia, by the superficial perineal
vessels and nerves. The aperture for the urethra is situated in
the middle line, one inch below the symphysis pubis. It is
not a clean-cut hole with sharp edges. The margins of the
opening, which are separated by a considerable interval from
the circumference of the urethra (Fig. 127), are prolonged
over the bulb of the penis so as to form for it an aponeurotic
capsule. As soon as the urethra gains the superficial aspect
of the ligament, it sinks into the bulb, and is carried forwards
through the entire length of the corpus spongiosum to its
external opening on the glans penis. On either side of the
urethral aperture there is a small opening in the ligament
which gives passage to the corresponding artery to the bulb.
Half an inch farther forwards the dorsal fierve of the penis
and the internal pudic artery pierce the ligament on either
side, close to the margin of the pubic arch, and under cover
of the corresponding crus penis.
The term " inferior or superficial layer " of the triangular
ligament is frequently applied to this membrane, which implies
that there is a deeper or superior layer to be studied in con-
nection with it ; and so there is. But whilst these layers are
very intimately connected, they must be looked upon as being
distinct structures. The superficial or inferior layer or the
triangular ligament proper is in the same morphological plane
as the bony wall of the pelvis and the thyroid membrane, and,
in fact, completes the pelvic wall in front. The superior or
deep layer is simply the parietal layer of the pelvic fascia
carried round to the front of the pelvis. Consequently the
connections of this layer can be examined very much better in
1—22"
34o ABDOMEN
conjunction with the pelvic fascia. Suffice it for the present
to say that inferiorly it is blended with the base of the
triangular ligament, but that it recedes from the surface as it
passes upwards, so that a narrow space or interval is left
between the two aponeurotic strata. Contained within this
interval are the following structures : —
1. The membranous portion of the urethra.
2. The dorsal vein of the penis.
3. The compressor urethra muscles.
4. Cowper's glands.
5. The internal pudic vessels, the dorsal nerves of the penis, and
the artery to the bulb.
Dissection. — To expose these parts, the superficial layer of the triangular
ligament must be raised upon one side of the body. It should be carefully
preserved upon the opposite side, for in the subsequent dissection of the
pelvis it is required as a landmark. On the side selected detach the
ligament from the margin of the pubic arch, and, cautiously raising it from
the subjacent structures, throw it inwards towards the bulb.
Membranous Portion of the Urethra. — The canal of the
urethra is subdivided for descriptive purposes into three parts,
according to the structures which are in relation to its walls
as it passes from the bladder to its termination on the glans
penis. These are — (1) the prostatic portion ; (2) the mem-
branous or muscular portion ; and (3) the spongy portion.
Each of these subdivisions has a very definite relation to
the triangular ligament ; the prostatic part is placed behind
both layers of this ligament ; the membranous part is situated
between the two layers of the ligament ; whilst the spongy
portion lies in front of the ligament.
Now that the superficial layer of the triangular ligament is
removed upon one side, the student can readily feel with the
point of the finger the staff as it lies within the membranous
portion of the urethra. He should examine the surroundings
of this canal. It is the shortest subdivision of the urethra,
and is distant about one inch from the symphysis pubis.
Throughout its entire extent it is enveloped by the fibres of
the compressor urethrae muscle, and on this account it is some-
times called the muscular part of the urethra. On each side,
and at a lower level, is Cowper's gland, whilst between it and
the symphysis pubis is the dorsal vein of the penis as it
extends backwards between the two layers of the triangular
ligament.
Compressor Urethrae (musculus transversus perinei pro-
MALE PERINEUM 341
fundus). — This is a fan -shaped muscle. It has a narrow
tendinous origin from the pubic arch close to the junction of
the pubic and ischial rami. Expanding as it passes inwards
towards the urethra, its fibres arrange themselves into two
layers, which enclose between them the entire extent of the
membranous portion of the urethra. The muscles of opposite
sides meet therefore in the middle line, and the muscular fibres
which compose the two layers are inserted into a median
raphe, both upon the upper and lower aspects of the urethra.
This muscle is supplied by one or two delicate twigs from
the perineal division of the pudic nerve.
Cowper's Glands (glandulse bulbo-urethrales). — As a
general rule, these glands can readily be detected by raising
the lower fibres of the compressor urethras. They are small
lobulated bodies of a deep yellow colour, and resemble peas
both in size and shape. They are placed one on each side
of the middle line, immediately below the membranous part
of the urethra, and are overlapped by the posterior part of
the bulb — separated from it, however, by the superficial
layer of the triangular ligament. From each a minute duct
proceeds, but this duct does not open into the membranous
portion of the urethra. It passes forwards between the wall
of the urethra and the substance of the bulb for the distance
of one inch, and opens on the floor of the spongy part of the
urethra.
Internal Pudic Artery (arteria pudenda interna). — The
pudic artery is a branch of the internal iliac. It is met with
in three different regions of the body — viz. (1) within the
cavity of the pelvis; (2) in the gluteal region, where it lies
upon the spine of the ischium ; and (3) in the perineal space.
It is consequently described as consisting of a pelvic, a gluteal,
and a perineal part. The perineal or third part of the pudic
artery enters the perineum by passing through the small sacro-
sciatic foramen. At first it is placed deeply ; but, as it is
traced forwards, it is found to become more superficial, and,
at the same time, to incline inwards, so that, at its termination,
it lies close to the middle line of the body.
In the rectal triangle the pudic artery is contained within
a sheath, termed Alcock's canal, which is formed by the
splitting of that part of the parietal pelvic fascia which forms
the outer wall of the ischio-rectal fossa. It lies fully an inch
and a half above the level of the lowest part of the ischial
1—22 b
34^
ABDOMEN
tuberosity, and is accompanied by two veins and the two
divisions of the pudic nerve. Of the latter the dorsal nerve
of the penis lies above it and the perineal nerve below it.
Reaching the base of the urethral triangle, the pudic artery
insinuates itself between the two layers of the triangular
ligament, and, gradually emerging from under cover of the
bone, proceeds forwards along the edge of the pubic arch to
a point about half an inch below the symphysis, where it
Bladder
Pelvic fascia
Obturator
interims
Prostate
Prostatic
urethra
Levator ant
Pubic arch -
Constrictor urethrae \r^iii
Triangular ligament \ Sgjt
(superficial layer) ^\^f
Cms peni~ -«— •
Erector penis
Superficial perineal
vessels and nerves
Fascia of Colles
Vi>ceral pelvic
' fascia
- Pelvic fascia
. Sheath of
prostate
" Anal fast ia
.Parietal pelvic
fascia
• Obturator
membrane
Triangular liga-
ment (deep layer)
--Pudic vessels and
nerve
Crus penis covered by
erector penis
Ejaculator urinae covering
the bulb of penis
FlG. 128. — Vertical section | schematic) through the pubic arch to show the
two perineal compartments.
pierces the superficial layer of the triangular ligament, and
immediately ends by dividing into two branches under cover
of the crus penis — viz., (1) the artery to the corpus caver-
nosum, and (2) the dorsal artery of the penis (Fig. 127,
P- 33*)-
Branches of the Pudic Artery. — The pudic has already
been seen to give off the inferior hamor-rhoidal, the superficial
perineal, and the transverse perineal arteries, and to divide into
its two terminal branches — the dorsal artery of the penis and
the artery to the corpus cavernosa m. Between the layers of the
triangular ligament it gives origin to the artery to the bulb.
MALE PERINEUM 343
The artery to the bulb is a short wide vessel which springs
from the pudic about a quarter of an inch above the level of
the base of the triangular ligament. It passes transversely
inwards between the two layers of this ligament, and, giving
a small twig to Cowper's gland, it enters the substance of the
bulb. It supplies the bulb and corpus spongiosum with
blood.
The artery to the corpus caver?wsu?n pierces the inner aspect
of the crus penis, and is carried forward in the substance of
the corpus cavernosum, which it supplies with blood.
The dorsal artery of the pern's runs forward in the interval
between the crura penis, and, passing between the two layers
of the suspensory ligament, gains the dorsum of the penis,
where it will be afterwards traced.
Pudic Nerve (nervus pudendus). — The pudic nerve is a
branch of the sacral plexus. Following the internal pudic
artery, it enters Alcock's canal, and after giving off the inferior
hcemorrhoidal nerve, it ! divides into two terminal divisions —
viz., (1) the perineal nerve, and (2) the dorsal nerve of the
penis.
The perineal nerve has been seen to break up into the
following branches : —
r, , f I. The posterior superficial perineal.
Cutaneous. { -, r . r • •< ■ i
[ 2. 1 he anterior superficial perineal.
( 1. The ejaculator urinre.
. , , 2. The erector penis.
Muscular. -{ t,, r
3. 1 he transversus pennei.
\ 4. The compressor urethral.
It also supplies one or two branches to the bulb and the
corpus spongiosum penis.
The dorsal nerve of the pe?iis follows the pudic artery
between the two layers of the triangular ligament, where it lies
more completely under shelter of the side of the pubic arch
than the artery. Finally, piercing the superficial layer of the
triangular ligament, about half an inch below the symphysis
pubis, it accompanies the dorsal artery of the penis. At the
root of the penis it supplies one or two twigs to the corpus
cavernosum.
The dissection of the perineum is now completed, but whilst the body is
in the lithotomy position, and the various parts of the perineum exposed,
the student should consider what structures still cover the perineal aspect
of the prostate gland. Three layers would still require to be removed to
bring the prostate into view — viz., (1) the compressor urethra: muscle ; (2)
1—22 c
344
ABDOMEN
the parietal pelvic fascia or the deep layer of the triangular ligament ; (3)
the anterior fibres of the levator ani muscle. Such being the case, it will
be apparent that within the limits of the urogenital triangle, and dissecting
from the surface towards the prostate gland, we meet with an alternation
of muscular and fascial strata, viz. : —
Artery of corpus cavernosum
Dorsal artery of penis —
Artery of bulb
Internal pudic artery
Cowper's gland
Fig. 129. — Deep dissection, in which the lower portion of the
levatores ani muscles have been removed, and the external
sphincter detached from the central point of the perineum, and
the rectum turned back. — (From Gray's Anatomy.)
I.
The fascia of Colles.
Superficial perineal m uscles.
Triangular ligament.
Compressor urethra muscle.
Parietal pelvic fascia or deep layer of triangular ligament.
Levator ani muscle.
7. Sheath of prostate.
Further, the fasciae of the urogenital triangle are so arranged that they
form a superficial and a deep compartment, and within one or other of
these all the structures of this division of the perineum are contained
(Fig. 128).
MALE PERINEUM 345
The superficial compartment is bounded in front by the fascia of Colles,
behind by the triangular ligament, laterally by the attachment of these to
the margins of the pubic arch, and inferiorly by the blending of the fascia
of Colles with the base of the triangular ligament. For the contents of
this compartment see p. 325.
The deep compartment is the interval between the triangular ligament
and the parietal pelvic fascia, and the structures which it contains are
enumerated at p. 340 (Fig. 127).
A pad of tow, soaked in a mixture of spirit and carbolic
acid, should be placed in the perineum, and the flaps of skin
carefully stitched over it. On the third day after the body
has been brought into the dissecting-room, it is placed upon
its face, and the dissectors of the abdomen stop work until
the subject is turned, which is done four days later.
FEMALE PERINEUM.
The boundaries of the female perineum are identical with
those in the male. The region, however, is wider and' of
greater extent. For purposes of description, it is subdivided
by an imaginary transverse line drawn in front of the anus
and the tuberosities of the ischium into a posterior rectal
triangle and an anterior urogenital triangle.
External Anatomy. — The rectal triangle presents the same
points for consideration as in the male. The external anatomy
of the urogenital triangle demands the careful study of the
student, because here we find the external organs of genera-
tion. They are —
1. The mons Veneris.
2. The labia majora.
3. The labia minora.
4. The clitoris.
5. The urethral opening.
6. The vaginal orifice.
All these parts are included under the common term of
Vulva.
Mons Veneris. — This is a marked cushion-like eminence
situated in front of the pubes. This projection is due to
a collection of adipose tissue under the integument. It is
covered by hair.
Labia Majora. — These correspond to the scrotum in the
male, cleft along the middle line. They are two rounded folds,
which commence in front at the mons Veneris and extend
downwards and backwards towards the anus. They diminish
346
ABDOMEN
in thickness as they proceed backwards, and anteriorly they
unite to constitute the afiterior commissure. Externally, they
are covered by skin studded with scattered hairs, whilst inter-
nally they are coated with smooth humid integument, the
free surface of which is lubricated by a semi-solid secretion,
derived from numerous sebaceous glands which open upon it.
During parturition, the labia majora are unfolded, and thus
give the vagina a greater capability of dilatation.
The labia majora enclose an elliptical fissure, which is
termed the pudendal deft, or the urogenital fissure, on account
of its containing the apertures of the urethra and vagina.
Within this fissure a
slightly marked cres-
centic fold of integu-
ment stretching be-
tween the hinder parts
of the labia majora will
be observed. This fold
receives the name of
the " fourchette " or
• \ frenulum pude?idi. ' '
It is usually ruptured
in first labours.
Between the four-
chette and the entrance
to the vagina there is
a depression which is known as the fossa navicularis.
It may be well for the student to bear in mind that the
term " perineum " in the language of the obstetric surgeon is
used in a very restricted sense. It is given to the narrow
interval which exists between the anus and the fourchette.
Labia Minora or Nymphae. — These represent the male
prepuce. They are two pendulous folds of integument which
lie within the labia majora. To display them fully the labia
majora must be pulled apart. They are placed one on each
side of the vaginal orifice. As they proceed forwards they
become more prominent, and at the same time converge so
as to approximate to each other more closely. Reaching the
clitoris, each terminates by splitting into two divisions or folds.
The smaller and lower fold is attached to the under surface
of the clitoris, and receives the name of frenulum clitoridis.
The upper fold arches over the clitoris like a hood, and unites
FlG. 130. — Outlet of Female Pelvis.
FEMALE PERINEUM
347
with the corresponding fold of the opposite side to form the
prceputium clitoridis.
Praeputium_
clitoridis
Vestibulum
vagina; (an-
terior part)
Orincium_
vagina;
I OSS .
navicularis
_Glans clitoridis
-Frenulum clitoridi:
-Labium majus
.Labium minus
JJrificium urethra;
externum
Commissura
"posterior
FlG. 131. — Female External Genital Org
The fourchette is seen stretching across behind the fossa navicularis and in
front of the posterior commissure. The ducts of Bartholin's glands open
in the intervals between the vaginal orifice an^ the inner edges of the
labia minora. (Dixon. 1
Clitoris. — The clitoris is the homologue of the penis, and,
notwithstanding its diminutive proportions, it presents a
348 ABDOMEN
close resemblance to the male organ both in appearance and
structure. It is a minute elongated projection placed below
the anterior commissure, and surmounted by a sensitive
rounded tubercle called the glans, but it is not traversed by
the urethra. The manner in which its prepuce and frenum
are formed has already been described. To obtain a proper
view of the clitoris the student must lay hold of the glans
with the forceps and draw it out from the prepuce.
Vestibule. — The dissector should next take note of a
smooth triangular interval which exists between the clitoris
and the entrance to the vagina. The term vestibule is given
to this area. It is bounded laterally by the nymphae, and
towards its lower part or base is seen the orifice of the
urethra.
The triangular outline of the vestibule is only seen when
the labia are forcibly drawn apart from each other. In the
natural condition of parts the labia are in close apposition, and
the vestibule is then a deep recess which represents the bottom
of the pudendal cleft, between the clitoris and the vagina.
Urethral Orifice. — This lies close to the opening of the
vagina, about one inch below the clitoris. It usually presents
the appearance of a vertical slit, and the mucous membrane
around it is prominent, pouting and slightly puckered, so that
when the tip of the finger is passed over the vestibular area
the opening can readily be distinguished by touch.
Vaginal Orifice. — The vaginal opening in the virgin is
partially closed by the hymen — a semilunar fold of mucous
membrane attached to the posterior aspect and sides of the
entrance to the vagina, and presenting a free concave margin
towards the pubes. The form of the hymen, however, is very
variable. Sometimes it is present in the shape of a septum
attached around the entire circumference of the vaginal
entrance, but pierced in the centre by a circular opening or
a vertical slit ; again, it may be cribriform or fringed along its
free margin. Lastly, it may constitute a complete septum
across the opening of the vaginal canal. In this case awkward
results ensue from the retention of the menstrual fluid. After
it has been ruptured its position is marked by certain rounded
elevations which have received the name of caruncula
??iyrtiformes.
Close to each side of the vaginal orifice, in the groove
between it and the posterior part of the labium minus, is the
FEMALE PERINEUM 349
opening of the duct of Bartoliris gland, an orifice just visible
to the naked eye.
Passage of Catheter and Examination of Os Uteri. — The
dissector should now practise the passing of the female
catheter, and afterwards introduce a speculum into the vagina,
so as to obtain a view of the os uteri.
In passing the catheter the forefinger of the left hand
should be placed in the orifice of the vagina, with its palmar
surface directed upwards towards the pubes. If the instrument
be now passed along this finger, and the point raised slightly
when it reaches the entrance to the vagina, a little manipula-
tion will cause it to enter the urethra.
When the speculum is introduced into the vagina, the points
to be noted in connection with the os uteri are: — (1) the
small size of the opening; (2) the two rounded and thick lips
which bound this aperture. In the virgin the opening is
circular, but in women who have borne children it is somewhat
transverse and often scarred. Note further that the anterior
lip is the thicker and shorter of the two, whilst the posterior
lip is the longer.
Reflection of Skin. — The rectum should be moderately filled with tow,
and the vulva and anal orifice stitched up. — Incisions — (1) A transverse in-
cision should, in the first place, be carried from one ischial tuberosity to the
other, in front of the anus. (2) The urogenital fissure and the orifice of the
anus should next be closely encircled by incisions, and these joined by a
cut along the middle line. (3) Lastly, carry an incision forwards from the
second or third piece of the coccyx along the middle line to the cut which
surrounds the anus.
Four flaps are thus marked out ; the two anterior may be thrown for-
wards and outwards, and the two posterior backwards and outwards.
Superficial Fascia. — The superficial fascia of the perineum
is now laid bare. In the rectal triangle it agrees in every
particular with the same portion of fascia in the male. In the
anterior or urogenital triangle, however, owing to the difference
in the external organs of generation, there is a slight modifica-
tion. It presents the same two layers. In the superficial fatty
layer, where it covers the labia majora, there are dartos fibres
similar to those in the scrotum of the male. The deeper
layer has the same attachments as in the male, viz., to the
anterior lips of the pubic arch, and to the base of the triangular
ligament ; but it is not so membranaceous, and consequently
does not form so distinct a stratum. The two fascial pouches
are also present in the female, and are sometimes spoken of as
35°
ABDOMEN
the vnlvo-scrotal sacs. Their separation along the middle line
is not due to the interposition of a median septum, as in the
male, but to the presence of the urogenital fissure.
Rectal Triangle.
Nothing need be added to what has already been written
regarding this portion of the perineal space in the male. In
both sexes the steps of the dissection and the parts found are
precisely the same {vide p. 326).
Urogenital Triangle.
Superficial Perineal Vessels and Nerves. — Under this
heading we include two arteries and three nerves, viz. : —
. .,,.-,. f The superficial perineal artery.
. ; Dies. Jy rp^e transverse perineal artery.
( The posterior superficial perineal nerve.
Nerves. \ The anterior superficial perineal nerve.
(_ The long pudendal nerve.
They have precisely the same disposition as the corre-
sponding vessels and nerves in the male, with this exception,
that they are somewhat smaller, and are distributed to the
labium majus, instead of to the scrotum. For a detailed
description of these structures, the student may refer to p. 331.
Dissection. — The superficial perineal vessels and nerves should now be
divided and thrown backwards, and the superficial perineal muscles cleaned.
These are three in number, viz. , the transversus perinei, the erector
clitoridis, and the sphincter vagince. The two first have a similar position
to the corresponding muscles in the male ; the sphincter vaginae lies upon
the side of the vagina close to its orifice. To obtain a good view of these
muscles the superficial fascia and the labia should be dissected away.
In cleaning the muscles the dissector should look for the small nerve
twigs which are given to each by the perineal division of the internal pudic
nerve.
Superficial Perineal Muscles. — The transversus perinei has
the same disposition- as in the male, but it is rare to find it
so well marked in the female. In most subjects its fibres are
pale, and it is generally very difficult to define. It is a
slender fasciculus which takes origin from the inner surface
of the ramus of the ischium close to the tuberosity, and
passes obliquely forwards and inwards to its insertion into the
central point of the perineum.
FEMALE PERINEUM
35i
In the female the central point of the perineum is placed
behind the vaginal orifice.
The erector clitoridis corresponds with the erector penis in
the male. It is a small muscle which arises from the inner
aspect of the ischial tuberosity, and is inserted by a tendinous
expansion on the surface of the crus clitoridis.
The sphincter vagina is the representative of the ejaculator
urinse of the male. It is a true sphincter muscle, and
Erector clitoridis
Sphincter vaginae
Erector clitoridis
Transversus perinei
■• ani
Gluteus maximus
Sphincter ani extemus
Fig. 132. — Muscles of the Female Perineum (Peter Thompson).
consists of two halves, which are placed one on each side of
the vaginal orifice and vestibule, and are closely adapted to
the surfaces of the two halves of the vaginal bulb. Posteriorly
the fibres of opposite sides unite behind the vaginal opening,
and are attached to the central point of the perineum, some
of the fibres intermixing with those of the sphincter ani.
Anteriorly the two portions of the muscle become narrower.
and, converging towards the middle line, are attached to the
sides of the clitoris. In some cases a small fasciculus on each
side may be observed to reach the dorsum of the clitoris, and
there gain insertion into a tendinous expansion which lies
352 ABDOMEN
superficial to the dorsal vein. This fasciculus is comparable
with the anterior fibres of the ejaculator urinal in the male,
which embrace the circumference of the body of the penis.
Perineal Triangle. — The dissector should now observe that
the three perineal muscles form the sides of a small triangle,
the floor of which is constituted by the superficial layer of
the triangular ligament.
Perineal Body. — It has been already stated that the term
" perineum " is confined by the obstetrician to the narrow
interval between the fourchette and the anus. Now that this
part has been dissected, it will be seen to consist of an
indefinite mass of fibrous and muscular tissue, which occupies
the interval between the rectum and the vagina. This is
known as the perineal body. Muscular tissue belonging to the
sphincter ani, levatores ani, and sphincter vaginae, together with
the central point of the perineum, enter into its constitution.
Dissection. — The sphincter vaginae should now be carefully raised from
the surface of the bulb, and the erector muscle from the surface of the crus
clitoridis. The transversus perinei muscle may be removed at the same
time.
Bulb of the Vestibule. — The bulb of the vestibule is now
displayed. It consists of two oblong bodies, composed of
erectile tissue, placed one on each side of the vestibule and
entrance to the vagina. Somewhat narrow in front, they
expand as they pass backwards, and each is invested by a
fibrous capsule derived from the triangular ligament, upon
the anterior surface of which they rest. Externally they present
a rounded convex surface which is coated with the sphincter
vaginae muscle, whilst internally, each erectile mass rests upon
the deep surface of the mucous membrane of the vagina.
In front of the urethra, between it and the clitoris, the two
halves of the bulb are brought into direct communication with
each other by a venous plexus called the pars intermedia,
which in turn is continuous with the erectile tissue of the
glans clitoridis. To obtain a proper idea of these connections,
it is necessary to study specimens which have been specially
injected and prepared.
The arrangement of erectile tissue in the female corre-
sponds more or less closely with the condition present in the
male. The apparent dissimilarity is due to the presence of
the urogenital fissure and orifice of the . vagina. Let us
suppose for a moment that the latter is obliterated, and
FEMALE PERINEUM 353
that the vestibule is closed in the form of a canal which
carries the urethra forwards to the extremity of the clitoris.
The two halves of the bulb would then be in contact with
each other, and its entire surface would be covered by a
muscular stratum, after the manner of the bulb and ejacu-
lator urinae in the male. Further, the urethra would be
surrounded by erectile tissue, and the pars inier?7iedia would
be seen to correspond to some extent to that portion of the
corpus spongiosum which in the male lies in front of the
bulb, and becomes continuous with the glans.
Dissection. — If the stitches uniting the lips of the pudendal cleft have
not been already removed they should now be taken away. The crura
clitoridis have been exposed by the removal of the erector muscles. To
obtain a good view of the entire organ, strip the mucous membrane from
the body of the clitoris, and clear away the loose tissue which surrounds it.
In doing this, however, remember that on its dorsal aspect certain vessels
and nerves run forwards to reach the glans, and that suspending it to. the
front of the pubes there is the suspensory ligament.
Clitoris. — The body of the clitoris is composed of two
cylindrical erectile bodies called the corpora cavernosa, which
correspond with the structures that bear the same name in
the male. Along the middle line they are united by their
inner surfaces, and the erectile tissue of the one is separated
from that of the other by an imperfect pectiniform septum.
The body of the clitoris is about an inch and a half long,
and is bent in a downward direction on itself at the lower
border of the symphysis pubis. Anteriorly it terminates in
a small rounded tubercle, which bears the name of the glans
clitoridis. The glans, however, is not structurally continuous
with the corpora cavernosa. It is a little mass of erectile
tissue continuous with the pars intermedia, and fitting into a
slight concavity which is formed for its reception on the
extremities of the corpora cavernosa. Posteriorly, opposite
the lower part of the symphysis pubis, the corpora cavernosa
separate, and diverging widely from each other, form the
crura clitoridis. Each crus is attached by its deep surface to
the rami of the pubis and ischium, and is covered by its
own erector muscle.
The clitoris, then, consists of three parts: — (1) a glans
continuous with the pars intermedia ; (2) a body composed of
two corpora cavernosa lying side by side and united along
the middle line ; and (3) tzvo crura attached to the sides of
the pubic arch. We have seen that the pars intermedia
" vol. 1 — 28
354
ABDOMEN
corresponds with the corpus spongiosum in the male. This
apparatus in the female, therefore, closely resembles the
penis in the male, the chief differences being the diminutive
size of the clitoris, and the fact that the glans clitoridis is not
perforated by the urethra.
Dissection. — Detach the crura clitoridis from the sides of the pubic arch
and throw them aside. This dissection requires care, because the pudic
arteries, the' dorsal nerves of the clitoris, and the small arteries which enter
CATUS URINARIUS.
. -TRIANGULAR
Bartholin's gland
Vagina
Central point of perineum
Fig. 133. — Dissection of Female Perineum to show the Clitoris and the
Bulb of the Vestibule.
the crura, are very apt to be injured. The pudic vessels and the dorsal
nerve will be seen piercing the triangular ligament about half an inch
below the symphysis pubis, and a little way external to the middle line.
Triangular Ligament. — A good view is now obtained of the
triangular ligament. Owing to the greater width of the pubic
arch, it is a more extensive membrane than in the male. It
does not possess the same strength, however, and is not so
perfect, seeing that it is pierced by the vaginal canal.
In the middle line it is pierced fully an inch below the
symphysis pubis by the urethra, and immediately below the
urethral opening by the wide vaginal canal. Its base is
perforated by the superficial perineal vessels and nerves,
btiNLALiL r&KLNhjUM. 355
whilst the internal pudic artery and the dorsal nerve of the
clitoris pierce it about half an inch below the symphysis.
The dorsal vein of the clitoris passes backwards through
an oval opening between the transverse perineal ligament
and the subpubic ligament.
The so-called deep layer of the triangular ligament is really
a part of the parietal layer of the pelvic fascia. Opposite
the pubic arch the deep layer of the triangular ligament by
its lower border fuses with the base of the triangular ligament.
As it is traced upwards, however, it recedes from the triangular
ligament, and consequently a space or interval is left between
them.
Dissection. — -The triangular ligament should be reflected upon one side.
Detach it from the margin of the pubic arch and throw it inwards. The
pudic vessels and the dorsal nerve of the clitoris, together with the
compressor urethrre muscle, may now be examined.
Urethra. — The female urethra is a short canal, which
extends from the neck of the bladder to its orifice on the
vestibule. It measures about one and a half inches in length,
and has an oblique and slightly curved course from above
downwards and forwards. The concavity of the curve is
directed forwards. So close is its relation to the anterior
wall of the vagina, that it may almost be said to be embedded
in it.
At the present stage of the dissection, the urethral canal is
seen to be covered by the fibres of the compressor urethrae
muscle.
A leading peculiarity of the female urethra is its great dilatability.
Cases are on record in which vesical calculi weighing from two to four
ounces have traversed it, and thus escaped from the bladder. It thus
happens that in the extraction of foreign substances from the female
bladder, it is rarely necessary to have recourse to the knife.
Compressor Urethrae. — This muscle differs somewhat from
the corresponding muscle in the male. It has the same
origin (viz. from the inner aspect of the pubic arch at the
junction of the pubic and ischial rami), and it also divides
into two bundles ; but these have not the same intimate
relation to the urethra. The upper or anterior bundle
spreads out upon the upper or anterior surface of the
urethra, whilst the lower or posterior bundle spreads out
upon the wall of the vagina.
The Vagina will be described in connection with the
pelvic viscera.
i—23 a
356 ABDOMEN
Bartholin's Glands. — These glands are the representatives
in the female of Cowper's glands in the male. They are two
round or oblong bodies about the size of a horse-bean, placed
one upon each side of the entrance to the vagina immediately
behind the rounded end of the bulb, and under cover of the
sphincter vaginas. A long duct proceeds from each gland,
and opens in the angle between the nympha and the hymen
or carunculse myrtiformes (Fig. 131, p. 347).
Internal Pudic Vessels and Nerve. — The internal pudic
vessels and nerve have a similar disposition to the corre-
sponding vessels and nerve in the male (p. 341). If anything,
they are somewhat smaller.
The student must therefore look for the artery to the bulb,
a branch of the internal pudic, which in this case is given to
the bulb of the vagina, and the two terminal branches of
the internal pudic artery, viz., the dorsal artery of the clitoris,
and the artery to the corpus cavemosum.
The internal pudic nerve ends by dividing into the
perineal nerve and the dorsal nerve of the clitoris.
The perineal nerve gives off — (i)the anterior and posterior
superficial perineal branches to the skin covering the labium
majus ; (2) muscular twigs to all the perineal muscles; and
(3) a branch to the bulb of the vagina.
The dorsal nerve of the clitoris gives a twig to the corpus
cavernosum, and runs forwards with the artery of the same
name between the crura to reach the dorsum of the clitoris.
Dorsal Vessels and Nerves of the Clitoris. — On the
dorsum of the clitoris a little dissection will display the dorsal
vein occupying the groove in the middle line, with a dorsal
artery and nerve lying upon each side of it.
The arteries and nerves should be traced forwards to
their distribution in the glans.
The dorsal vein takes origin in the glans. As it proceeds
backwards it receives certain superficial veins and also
tributaries from the corpora cavernosa. At the root of the
clitoris it dips downwards between the crura, and, passing
between the triangular and the subpubic ligaments, is con-
tinued backwards into the pelvis to join the plexus of veins
around the neck of the bladder.
ABDOMINAL WW I I 357
ABDOMINAL WALL.
On the fifth day, after the dissection of the perineum is
completed, the body is placed upon its back, with blocks
under the chest and pelvis, and the dissectors of the abdomen
begin the dissection of the abdominal wall (Fig. 134).
External Anatomy. — It is well, however, before proceeding
to the actual dissection of the part, that some attention should
be paid to the general configuration and bony prominences
of the region. If the subject is obese the abdomen presents
a smooth, rounded, and protuberant appearance ; if, on the
other hand, it is spare, the abdominal wall is depressed, and
the lower margin of the thorax above, and the pubes, crest of
the ilium, and Poupart's ligament below, stand out in marked
relief. In .the middle line, the student will notice a linear
depression extending downwards towards the symphysis.
This corresponds with the linea alba or the interval between
the two recti muscles. It is an important line to the
surgeon, because here the wall of the abdomen is thin and
devoid of blood-vessels. In this line the trocar is intro-
duced into the abdomen in the operation of paracentesis
abdominis or tapping.
In this linear depression, rather nearer the pubes than
the ensiform cartilage, is the umbilicus or navel. This is a
depressed and puckered cicatrix, the floor of which is raised
in the form of a little button-like knob. It results from the
closure of an opening in the abdominal wall of the fcetus,
through which passed the constituents of the umbilical cord
— viz., the umbilical vein, the two allantoic or hypogastric
arteries, and the urachus.
In powerful well -developed subjects the rectus muscle
stands out on each side of the middle line, and its outer
margin gives rise to a curved line, the concavity of which is
directed inwards. This line corresponds to the linea semi-
lunaris— i.e., the line along which the aponeurotic tendon of
the internal oblique muscle splits to enclose the rectus. The
linea semilunaris may, on certain occasions, be selected by the
surgeon as the site for incisions through the abdominal wall.
The student should now place his finger upon the upper
part of the symphysis pubis and carry it outwards, over the
I — 23 ft
358 ABDOMEN
pubic crest, to the pubic spine ; from this he should follow
the line of Poupart's ligament to the anterior superior spine
of the ilium, and, having identified these parts, let him next
endeavour to determine the position of the external abdominal
ring. This is easily done in a male subject. Immediately
external to the spine of the os pubis the spermatic cord can
be felt as it passes over Poupart's ligament to reach the
scrotum. Taking this as a guide, push the loose skin of the
scrotum upwards before the finger. The tip of the finger
enters the opening, the sharp margins of which can now be
felt.
The spermatic cord, as it passes downwards into the
scrotum, should be taken between the finger and thumb.
On pressure being applied the vas deferens can be easily dis-
tinguished at the back of the cord, by the hard whipcord-like
feel that it conveys to the fingers.
The crest of the ilium, as it proceeds upwards and back-
wards from^the anterior superior spine, can be easily felt.
Indeed, in most cases it is visible to the eye for a distance
of about two and a half inches. At the point where it dis-
appears from view a prominent tubercle is developed on its
outer lip, and it is here that the lateral outline of the trunk
joins' the ilium. It is the highest point of the iliac crest, there-
fore, that can be seen from the front. As we shall see later
on, use is made of this fact in subdividing the abdominal
cavity into regions.
In females who have borne children the skin over the
lower part of the abdomen is wrinkled and scarred.
Parts to be dissected. — A dissection of the abdominal wall
will display the following parts : —
1. Superficial fascia.
2. Cutaneous vessels and nerves.
3. The external oblique muscle.
4. The internal oblique muscle.
5. The lower six intercostal nerves and accompanying vessels ; the
ilio-inguinal and ilio-hypogastric nerves.
6. The transversalis muscle.
7. The rectus and pyramidalis muscles and the sheath of the rectus.
8. The transversalis fascia.
9. The deep epigastric and deep circumflex iliac arteries.
10. The superior epigastric and musculo-phrenic arteries.
11. The spermatic cord.
12. The inguinal canal.
13. The extra-peritoneal fat.
14. The parietal peritoneum.
ABDOMINAL WALL
359
Reflection of Skin. — Incisions — (i) Along the middle line of the body
from the ensiform cartilage to the symphysis pubis. At the navel the
knife should be carried round so as to surround it with a circular incision.
(2) From the ensiform cartilage transversely outwards around the chest,
as far back as the knife can be carried. (3) From the symphysis pubis
outwards along the line of Poupart's ligament to the anterior superior spine
of the ilium, and then backwards along the crest of the ilium (Fig. 134).
The large flap of skin thus mapped out should be carefully raised from
the subjacent superficial fascia and turned outwards. If the abdominal
wall is flaccid, the dissection may be facilitated by inflating the abdomen.
Make an incision through the umbilicus large enough to admit the nozzle
of the bellows or an injection-pipe fixed to a bicycle-pump, and when the
walls are quite tense secure the opening with twine, which has previously
been sewn round the lips of the incision.
Superficial Fascia. — The superficial fascia which is now-
laid bare is seen to present the same appearance, and possess
Fig. 134.
the same characters, as in other localities. Above, it is thin
and weak, and is directly continuous with the corresponding
fascia over the chest; below, it becomes more strongly marked,
and acquires a greater density. Towards the lower part of
the abdomen it consists of two layers — a fatty superficial
stratum called Camper's fascia, and a deep membranaceous
stratum termed Scarpa's fascia.
There is another point, however, in which the superficial
fascia differs somewhat from the same fascia in other parts of
the body. It is more elastic, and this elasticity is due to the
presence of elastic fibres in its deeper membranaceous part.
Over the lower part of the linea alba the elastic tissue is
generally seen collected in the form of a distinct band which
in the region of the symphysis pubis becomes connected with
the penis and its suspensory ligament. A reference to com-
360 ABDOMEN
parative anatomy gives interest to this fact. In the human
subject this elastic band is the rudimentary representative of
a continuous and distinct layer of yellow elastic tissue {the
abdominal tunic), which is present in the horse and other
quadrupeds in which the weight of the viscera is chiefly
sustained by the abdominal wall.
But what becomes of the two layers of the superficial fascia
if we follow them downwards from the front of the abdomen ?
The fatty layer of Camper is carried over Poupart's ligament,
and becomes directly continuous with the fatty superficial
fascia on the front of the thigh. The relations of the fascia
of Scarpa are very different. In the region of the pubes it is
carried continuously downwards over the spermatic cords, the
penis and scrotum, into the perineum, where it becomes con-
tinuous with the fascia of Colles. On the outer side of the
spermatic cord, in the region of the groin, it proceeds down-
wards, and ends immediately below Poupart's ligament by
blending with the fascia lata of the thigh.
These connections of the fascia of Scarpa are so important that it is
necessary to undertake a special dissection, in order that they may be
demonstrated. As this encroaches somewhat upon the region of the thigh,
it must be done in conjunction with the dissector of the lower limb. A
transverse incision should be made through the entire thickness of the
superficial fascia on the front of the abdomen from the anterior superior
spine of the ilium to the middle line of the abdomen. On raising the lower
edge of the divided fascia the two layers can be easily distinguished.
Insinuate the fingers between the fascia of Scarpa and the subjacent pearly-
looking tendon of the external oblique muscle. Little resistance will be
met, as the fascia of Scarpa is only bound down by some lax areolar tissue.
As the superficial fascia is thus raised from the aponeurosis of the external
oblique, the hypogastric branch of the ilio-hypogastric nerve will be seen
piercing the aponeurosis a little way above the external abdominal ring,
and then sinking into the deep surface of the superficial fascia. The fingers
can be readily carried downwards behind the fascia of Scarpa as far as
Potipart's ligament. Here it will be found that they can force their way
no farther. The passage of the hand into the thigh is barred by the
blending of the fascia of Scarpa with the fascia lata of the thigh. At this
level it ceases to exist ; it loses its identity by becoming fused with the deep
fascia of the thigh along the line of, and immediately below, Poupart's
ligament.
Towards the pubes the finger can be pushed downwards behind the
fascia of Scarpa and along the spermatic cord into the perineum. No
barrier opposes the passage of the finger in this direction. The continuity
of the fascia of Scarpa and the fascia of Colles is thus demonstrated.
If the dissector now recall the fact that in the urethral
triangle of the perineum the fascia of Colles is attached
laterally to the margins of the pubic arch, and posteriorly to
ABDOMINAL WALL 361
the base of the triangular ligament, whilst above the level of
the pubic crests it is spread over the front of the abdominal wall,
he will have little difficulty in understanding the course which
urine takes when extravasated from a rupture of the urethra
in front of the triangular ligament. The effused fluid is
directed upwards over the scrotum and penis, and along the
spermatic cords to the front of the abdomen. From the
abdomen it cannot pass downwards to the front of the thighs,
owing to the attachment of Scarpa's fascia to the fascia lata.
Unless vent be given to it by early and free incisions, it
will continue to ascend over the abdomen.
Cutaneous Nerves. — A dissection must now be made of
the cutaneous nerves of the abdomen. These are arranged
on the same plan as the cutaneous nerves of the chest. \\ e
have therefore to look for an anterior and a lateral series.
( 1. Anterior cutaneous nerves.
Anterior series. -J 2. Hypogastric branch of the ilio-hypogastric nerve.
( 3. The ilio-inguinal nerve.
[ 1. Lateral cutaneous nerves.
Lateral series. -J 2. Lateral or iliac branch of last dorsal nerve.
[ 3. Iliac branch of ilio-hypogastric nerve.
The anterior cutaneous nerves are the small terminal twigs of
the lower four or five intercostal nerves, and also ol the last
dorsal nerve. They pierce the aponeurotic sheath of the
rectus muscle at variable points, some close to the middle
line, and others a little distance from it. Entering the super-
ficial fascia, they run for a short distance outwards.
To find these nerves, the best plan to adopt is to divide the superficial
fascia along the middle line, and reflect it cautiously outwards. The small
arteries which accompany the nerves serve as guides.
The hypogastric nerve is the terminal twig of the ilio-
hypogastric, and it lies in series with the preceding. In the
dissection of the superficial fascia it has been seen piercing
the aponeurosis of the external oblique immediately above
the external abdominal ring.
The ilio-inguinal nerve comes out through the external
abdominal ring, and is distributed to the integument of the
scrotum and the inner aspect of the thigh.
The lateral cutaneous nerves are branches of the five lower
intercostal nerves. They become superficial between the
digitations of the external oblique muscle, and then each
divides into an anterior and posterior division. The posterior
362
ABDOMEN
divisions are small, and are directed backwards over the latis-
simus dorsi. The anterior divisions run forward, and a careful
External
oblique
thrown
forwards
Internal
oblique
Hypogastric
iranch of ilio-
hypogastric
poneurosis of
rnal oblique,
reflected
Cremaster
Conjoined
tendon
Pectoralis
major
/ Serratus
magnus
Obliquus
externus
Sheath of
rectus
Anterior
cutaneous
nerve
Aponeurosis of
external oblique
muscle
Intercolumnar
fibres
External
abdominal
ring
Triangular fascia
Spermatic cord
pIG T35. — Dissection pf Anterior Wall of the Abdomen. The obliquus
externus has been reflected on the right side.
dissector may trace them as far as the outer margin of the
rectus.
The iliac branch of the last dorsal corresponds with the
lateral cutaneous branches of the intercostal nerves. It differs
from the other members of the series in not dividing into an
ABDOMINAL WALL 363
anterior and a posterior branch, and in being destined for
the supply of the integument over the gluteal region. It
pierces the external oblique muscle in a line with the other
lateral nerves, and is then directed downwards over the
crest of the ilium. It crosses the iliac crest from one to
two inches behind the anterior superior spine.
The iliac branch of the ilio-hypogastric nerve is also distributed
to the skin of the gluteal region. It pierces the external
oblique immediately above the iliac crest, which it usually
crosses opposite the tubercle which projects from the outer
lip of the crest, about two and a half inches behind the
anterior superior spine of the ilium.
Cutaneous Vessels. — Cutaneous arteries are found accom-
panying the cutaneous nerves. Those which are associated
with the lateral cutaneous nerves are branches of the aortic
intercostal arteries, whilst those in relation to the anterior
cutaneous nerves are derived from the deep and superior
epigastric arteries, and also from the aortic intercostal arteries.
In addition to these, three small branches of the femoral
artery ramify in the superficial fascia of the groin.
These are —
1. The superficial pudic.
2. The superficial epigastric.
3. The superficial circumflex iliac.
They take origin in the thigh, a short distance below
Poupart's ligament, and, piercing the fascia lata, diverge
from each other in the superficial fascia.
The superficial pudic is directed inwards over the spermatic
cord, and gives branches to the skin of the scrotum and
under surface of the penis.
The superficial circumflex iliac proceeds outwards and
upwards along the line of Poupart's ligament, and ends in
the skin in the neighbourhood of the anterior superior spine
of the ilium.
The superficial epigastric takes a vertical course upwards,
and, crossing Poupart's ligament, ramifies in the superficial
fascia over the lower part of the abdomen. Its branches
extend as high as the level of the umbilicus.
The small veins which accompany these arteries open into
the internal saphenous vein.
Muscles of the Abdominal Wall. — The abdominal wall is
formed anteriorly and laterally by five pairs of muscles, and by
364 ABDOMEN
the aponeuroses which constitute their tendons. In front
are the two recti muscles and the two pyrami dales muscles.
The recti are placed parallel to the middle line, and extend
in a vertical direction from the pubic bones to the lower
margin of the thorax. On eich side three fleshy and aponeurotic
strata are met with as we dissect from the surface towards the
abdominal cavity. These strata are — (i) the external oblique
muscle; (2) the internal oblique muscle; (3) the transversalis
muscle. The direction taken by the muscular fibres which
compose each of these layers is different. The external
oblique corresponds in this respect with the external inter-
costal muscles ; the fibres proceed obliquely downwards and
forwards. Again, the internal oblique resembles the internal
intercostal muscles in the direction of its fibres ; they are
directed upwards and forwards, and thus the fibres of the
two oblique muscles cross each other like the limbs of the
letter X. Lastly, the fibres composing the transversalis
muscle pursue a horizontal or transverse course.
This difference of direction in the fibres which compose
these three strata is a source of strength to the fleshy part of
the abdominal wall, and offers an insurmountable barrier to
the protrusion of any of the abdominal contents. The two
oblique muscles and the transversalis are prolonged forwards
to the middle line in the form of aponeuroses. The union
of these with the corresponding aponeuroses of the opposite
side forms the lifiea alba — a strong band which extends in
the median line from the symphysis pubis to the ensiform
cartilage.
Dissection. — Remove the superficial fascia from the front of the abdomen.
This will expose the aponeurosis of the external oblique muscle. Towards
the thorax this aponeurosis is very thin, and is liable to injury, unless the
dissection be performed with care. Proceed cautiously also at the lower
part of the abdomen, above the inner end of Poupart's ligament. Here
the aponeurosis is pierced in the male by the spermatic cord. The lips of
the opening thus formed are prolonged downwards upon the cord in the
form of a thin membrane called the external spermatic fascia. In defining
this the blade of the knife must not be used. Work entirely with the
handle. The thin layer of deep fascia which is spread over the muscular
part of the external oblique muscle must also be removed. In doing this
it is not necessary to carry the knife in the direction of the fleshy fasciculi.
Indeed, the muscle can best be cleaned by carrying the knife at right angles
to the general direction of the fibres. In front, the deep fascia will be seen
to blend with the aponeurosis of the muscle, along the line of junction
between the tendinous and fleshy fibres. The slips of origin of the external
oblique muscle from the eight lower ribs must each be carefully defined.
ABDOMINAL Y\ALL
365
Obliquus Abdominis Externus. — The external oblique
muscle arises by eight pointed processes or digitations
from the outer surfaces and lower borders of the eight
lower ribs (Fig. 135). Of these, the upper five interdigitate
with the digitations of the serratus magnus, and the
lower three with those of the latissimus
dorsi. From this origin the fibres pro-
ceed downwards and forwards with varying
degrees of obliquity. The posterior fibres
have a nearly vertical direction, and are
inserted into the anterior half of the outer
lip of the crest of the ilium. The superior
fibres are almost horizontal, and the in-
termediate fibres are directed obliquely down-
wards and forwards, and both end in a strong
aponeurosis called the aponeurosis of the ex-
ternal oblique.
Superiorly, the aponeurosis of the external
oblique is very thin, and is carried forwards
to be attached to the ensiform cartilage. 0
It is from this part of it that the pectoralis
major derives fibres of origin. Inferiorly
it is attached to Poupart's ligament, which,
indeed, is simply the thickened lower border
of the aponeurosis folded back upon itself.
Between these attachments it proceeds for-
wards over the rectus, and is inserted
into the linea alba and into the front of
the os pubis.
In connection with this aponeurosis note
that it is broadest and strongest inferiorly, Fig. 136.— Crest of
that it is narrowest about the level of the
umbilicus, but that it widens somewhat again
towards the ribs. Superiorly it is so thin
that the fibres of the rectus muscle shine
through it.
External Abdominal Ring (annulus inguinalis subcutaneus)
(Figs. 137 and 138). — In the male, the aponeurosis of the
external oblique is pierced immediately above the pubes by
the spermatic cord ; in the female it is pierced, at the same
point and in the same manner, by the round ligament of the
uterus. The aperture which is thus formed receives the name
the Ilium as seen
from above I semi-
diagrammatic 1, with
Attachments of
Muscles mapped
out.
66
ABDOMEN
of the external abdominal ring. At the present stage of the
dissection this opening is not visible, because a thin fascial
covering is carried downwards from its lips upon the spermatic
cord or round ligament of the uterus. This is called the
external spermatic or the intercolumnar fascia. If the cord be
raised and rendered tense, this covering will be observed to
invest it completely, and to be somewhat funnel-shaped —
wide above, but closing upon the cord as it is traced down-
wards.
Elastic tissue passing down to
suspensory ligament of the penis
External abdominal ring
Aponeurosis of
the external
oblique
Poupart's
ligament
Intercolumnar
fibres
Cord covered
by cremasteric
fascia'
— Fascia of Scarpa
External
spermatic fascia
Internal
saphenous vein
Fig. 137. — Dissection of the External Abdominal Ring and
the parts in its vicinity.
With the point of the knife divide the external spermatic
fascia round the cord, and then, with the handle, define
the margins of the external abdominal ring. When this is
done, the dissector will observe that the term "ring," as applied
to this opening, is calculated to convey to the mind an errone-
ous impression. It is not circular, but triangular, in shape.
The direction of the opening is very oblique, the base of the
triangle being formed by the crest of the pubes, whilst the
apex is directed outwards and slightly upwards.
The external abdominal ring, therefore, is merely a small
gap or interval left between that portion of the aponeurosis
ABDOMINAL WALL
367
of the external oblique muscle which is inserted into Poupart's
ligament, and that portion which is inserted into the front of
the pubic bone. The margins of the aperture are termed
the pillars or crura of the ring. The internal or superior pillar
(crus superius) is flat and broad, and is attached to the
symphysis pubis. Some of its fibres cross the middle line,
decussate with the corresponding fibres of the other side, and
Sheath of rectus
Aponeurosis of external oblique
Intercolumnar
fibres
Poupart's
ligament
External abdominal
ring
Triangular fascia
Gimbernat's ligament
Fig. 138. — Dissection to show the connections of the lower part of
the Aponeurosis of the External Oblique Muscle.
are inserted into the front of the opposite pubic bone. The
external or inferior pillar (crus inferius) is simply the inner
end of Poupart's ligament. It is, therefore, thick and strong,
and is fixed to the pubic spine. The spermatic cord, as it
issues from the external abdominal ring, rests upon the
external pillar.
The size of the external abdominal ring is very variable.
In the male the average length may be said to be one inch,
and the breadth about half an inch. In the female it is
368 ABDOMEN
much smaller. In the female the round ligament of the uterus
will be found to end in the superficial fascia of the groin.
On a close inspection of the lower part of the external
abdominal aponeurosis, the student will observe a number of
cross fibres arching over its surface. These are called the
intercolumnar fibres (nbrae intercrurales), and in some cases
they are very strongly marked. They begin at Poupart's
ligament close to the iliac spine, and curve upwards and
inwards upon the aponeurosis above the external abdominal
ring. The function of these fibres is very evident, and the
term "intercolumnar" is derived from the part which they
play. They bind together the two pillars of the ring, and
prevent their further separation or divarication. There is a
direct continuity between the intercolumnar fibres and the
external spermatic fascia which clothes the cord, and conse-
quently, as we have already seen, the term " intercolumnar "
is frequently applied to the latter.
Reflection of the Obliquus Externus. — The external oblique muscle
should now be reflected. Begin by detaching each digitation from the rib
to which it is fixed. Between the last rib and the crest of the ilium the
posterior border of the muscle will be found free ; sometimes it is slightly
overlapped by the latissimus dorsi, but in other cases a small portion of the
internal oblique muscle can be observed in a triangular interval between
them (trigonum Petiti). These points can only be seen by tilting the body
slightly over on its opposite side. Raise the posterior border of the muscle
from the subjacent internal oblique, and divide the fleshy fibres which are
inserted into the crest of the ilium close to the bone. Next divide the
aponeurosis horizontally in a line leading from the anterior superior spine
of the ilium to the outer border of the rectus. The entire muscular portion,
and the greater part of the aponeurotic portion of the external oblique can
now be thrown forward. On approaching the outer border of the rectus,
the dissector must proceed with care, because a little beyond this the
anterior lamella of the aponeurosis of the internal oblique fuses with the
deep surface of the aponeurosis of the external oblique. Define the line of
union, and notice that it does not extend beyond the lower margin of the
thorax. Above this the rectus is simply covered by the aponeurosis of the
external oblique ; the outer margin of the muscle in this locality is bare,
and the hand can be freely passed between it and the costal cartilages.
On the left side of the body, the parts below the horizontal line drawn
from the anterior superior iliac spine to the outer border of the rectus, and
along which the aponeurosis of the external oblique muscle has been
divided, should be preserved intact for the special study of those parts which
are related to inguinal hernia. On the right side of the body divide the
lower part of the aponeurosis along the outer border of the rectus to the
pubes. This incision should pass to the inner side of the internal pillar of
the external abdominal ring, so that this opening may be preserved. The
triangular flap of aponeurosis may now be thrown downwards and out-
wards. By this proceeding we can study more successfully Poupart's
ligament, the entire extent of the internal oblique muscle, and the
cremaster muscle.
ABDOMINAL WALL 369
Poupart's Ligament (ligamentum inguinale). — Poupart's
ligament is merely the thickened lower border of the
aponeurosis of the external oblique folded backwards upon
itself. It thus presents a rounded surface towards the thigh
and a grooved surface towards the abdominal cavity. The
manner in which it is attached by its outer and inner
extremities deserves the close study of the dissector. Ex-
ternally it is fixed to the anterior superior spine of the ilium ;
internally it has a double attachment — viz. (1) to the pubic
spine, which may be considered as its attachment proper;
(2) through the medium of Gimbernat's ligament to the ilio-
pectineal line.
Poupart's ligament does not pursue a straight course
between its iliac and pubic attachments. It describes a
curve, the convexity of which is directed downwards and
outwards towards the thigh. By its lower border it gives
attachment to the fascia lata. When this is divided, Poupart's
ligament at once loses its curved direction.
Gimbernat's Ligament (ligamentum lacunare) (Fig. 138). —
This is a triangular process of aponeurotic fascia. Raise the
spermatic cord, and place the finger behind the inner end of
Poupart's ligament, and press downwards. The structure
upon which the finger rests is the ligament in question, and
the student should note that at this point it offers a barrier to
the passage of the finger into the thigh. With the handle of
the knife its shape and connections can be easily defined.
Its apex is fixed to the pubic spine ; by one margin it is
attached to the inner part of Poupart's ligament ; by its
other margin it is inserted for the distance of an inch into the
ilio-pectineal line. Its base is sharp, crescentic, and free,
and is directed outwards towards the femoral sheath. The
dissector should thoroughly realise that Gimbernat's ligament
is not an independent structure. It is merely the inner part
of the folded- back margin of Poupart's ligament which,
in the vicinity of the pubic spine, obtains an attachment
to bone.
Gimbernat's ligament occupies an oblique plane, its lower
femoral surface looking downwards and slightly forwards and
outwards, whilst its upper abdominal surface looks upwards
and slightly backwards and inwards. It is of importance that
the student should note the precise relation which this liga-
ment bears to the spermatic cord. Taken in conjunction
vol. 1 — 24
37o ABDOMEN
with Poupart's ligament and the aponeurosis of the external
oblique, it forms a gutter or groove in which the cord lies.
Triangular Fascia (Fig. 138). — The triangular fascia is a
small triangular piece of fascia which springs from the crest
of the pubic bone and the inner end of the ilio-pectineal line.
It passes upwards and inwards under cover of the internal
pillar of the external abdominal ring, and passes into the
linea alba. If the fibres which compose it are followed through
the linea alba, they will be found to be continuous with the
fibres of the aponeurosis of the external oblique muscle of
the opposite side. It must, therefore, be considered as an
additional insertion of this muscle. It is frequently so
poorly developed, that its true relations and connections are
demonstrated with difficulty, if indeed they are capable of
demonstration at all.
Dissection. — The internal oblique muscle should now be cleaned.
Towards its lower part it will be seen to be pierced by certain nerves, and
these must be preserved. Close to the iliac crest the iliac branches of the
ilio-hypogastric and last dorsal nerves will be noticed emerging from the
midst of its fleshy fibres, whilst in front it is pierced by the hypogastric
branch of the ilio-hypogastric and by the ilio-inguinal nerve. The former
of these appears near the anterior superior iliac spine, and then proceeds
forwards under cover of the external oblique aponeurosis, which it soon
pierces. The ilio-inguinal nerve will be found perforating the internal
oblique a little way in front of the hypogastric nerve and at a lower level.
It becomes superficial by passing through the external abdominal ring.
Care must be taken in defining the lower margin of the muscle to
preserve its relations to the spermatic cord, and not to injure the muscular
fasciculi which it gives to the cremaster muscle.
Obliquus Abdominis Internus (Fig. 135). — The internal
oblique muscle arises — (1) from the abdominal grooved surface
of Poupart's ligament in its outer half; (2) from the middle
lip of the anterior two-thirds of the iliac crest ; (3) from the
lumbar aponeurosis. From this origin the muscular fibres
radiate, but the general direction is from below upwards and
forwards. The posterior fibres ascend, and are inserted into
the lower borders of the cartilages of the lower four ribs. These
fibres occupy the same plane as the internal intercostal
muscles — indeed, they will be observed to be directly continuous
with the fibres of the internal intercostal muscles of the two
lower spaces. The lower fibres, or those springing from Poupart's
ligament, arch downwards and inwards, and join with the lower
fibres of the transversalis in a flat tendon, called the conjoined
tendon, which is inserted into the pubic crest, and into the ilio-
ABDOMINAL WALL
37i
pectineal line, behind Gimbernat's ligament and the triangular
fascia, for fully half an inch of its extent (Figs. 139 and 144).
The i?itermediate fibres proceed upwards and forwards, and end
in a strong aponeurosis, which extends from the lower margin
of the chest to the pubis. By this aponeurosis they gain in-
sertion into the lower borders of the seventh and eighth ribs
and the ensiform cartilage, and into the linea alba throughout
its entire length. The manner, however, in which the apo-
neurosis reaches the middle line requires special description.
Aponeurosis of internal oblique Internal oblique
Triangular fascia /
Poupart i
ligament
Conjoined
tendon
Cord covered by
cremaster
External
abdominal ring
Suspensory
ligament of
penis
Cord covered by
external sper-
matic fascia
Fascia of Scarpa
Fig. 139. — Dissection of the Inguinal Region. The aponeurosis
of the external oblique is turned down.
At the outer margin of the rectus muscle the aponeurosis
of the internal oblique splits into two layers — a superficial
and a deep. The superficial aponeurotic layer passes in front
of the rectus, and has already been seen to fuse with the
aponeurosis of the external oblique muscle. The deep layer is
carried inwards behind the rectus, and becomes incorporated
with the subjacent aponeurosis of the transversalis muscle.
But this arrangement does not hold good lower down than a
point about midway between the umbilicus and the pubes.
Below this point the tendon does not split, but passes entirely
in front of the rectus, to join the aponeurosis of the external
oblique.
It is important to mark exactly the relation which the
1—24 a
372
ABDOMEN
' Fascia
- transversalis
Poupart's
ligament
Spermatic
cord
lower part of the muscle bears to the spermatic cord. At
first the cord lies under cover of the fleshy fibres, but it soon
emerges, clothed by the cremaster muscle, and as it is con-
tinued downwards and inwards to the external abdominal
ring, it lies in front of the conjoined tendon. Especially
note the position of the conjoined tendon in relation to the
external abdominal ring. It lies immediately behind it, and gives
strength to this otherwise weak point in the abdominal parietes.
Cremaster Muscle. — This muscle supports the testicle and
spermatic cord, and is consequently peculiar to the male. It
arises from the inner
part of Poupart's liga-
ment, and also derives
fibres from the lower
border of the internal
oblique (rarely from the
lower border of the
transversalis muscle).
The fleshy fibres de-
scend upon the outer
and anterior aspects of
the cord in the form of
loops, the concavities
of which are directed
The depth
to which these loops
descend varies. Some
reach the tunica vagin-
alis of the testicle, and
the scrotum should now
be opened up on the right side, in order that they may be
traced downwards to this point ; the majority of the fibres,
however, do not reach so far down, some going no farther
than the external abdominal ring. Upon the posterior aspect
of the cord the loops are directed upwards, and some reaching
the os pubis, obtain a tendinous insertion into its spine and
crest.
It will be noticed that the cremasteric fleshy loops do not
form a complete investment for the cord and testicle. The
intervals between the fasciculi are occupied by areolar tissue,
and this combination of muscular and areolar tissue is some-
times termed the cremasteric fascia.
Fig. 140. — Diagram to illustrate the relation
of the lower border of the internal oblique
muscle to the cord, the conjoined tendon, and upwards.
the inguinal canal.
O.I. Internal oblique muscle.
C.T. Conjoined tendon.
The position of the external abdominal ring is
indicated by a dotted outline.
ABDOMINAL WALL 373
Reflection of Internal Oblique. — On the right side of the body the
entire muscle may be reflected, but on the left side preserve the lower
portion of it {i.e., that part which is still covered by the aponeurosis of
the external oblique) in situ. Begin below by dividing the muscular fibres
along the crest of the ilium. The depth to which the knife should be
carried is indicated by the dense areolar tissue which lies between it and
the subjacent transversalis muscle. An ascending branch from the deep
circumflex iliac artery will also serve as a guide. This vessel emerges
from the fibres of the transversalis close to the fore-part of the iliac crest,
and is then directed upwards upon its surface. Although this vessel has
not attained the dignity of a name, it is a very constant branch. On the
right side the fibres springing from Poupart's ligament should also be
severed, but on the left side carry the knife horizontally inwards, from the
anterior superior spine of the ilium to the outer margin of the rectus. Now
turn to the upper part of the muscle, and make an incision through it
along the lower margin of the thorax, from the outer border of the rectus
to the last rib. Lastly, carry the knife downwards, from the tip of the last
rib to the crest of the ilium.
The muscle freed in this manner can be thrown forwards towards the
outer border of the rectus. In doing this the dissector must proceed with
caution, because he has reached the plane of the main trunks of the nerves
of the abdominal wall and the arteries which accompany them. These
pass forwards between the internal oblique and transversalis, and, in raising
the former muscle, they are apt to adhere to its deep surface and be cut.
In all probability the student will experience considerable difficulty in
separating the lower part of the internal oblique from the corresponding
portion of the transversalis. At this level these two muscles are always
closely connected, and in some cases they may be even found to be partially
blended.
The cremaster muscle should also be reflected from the spermatic cord.
This can best be done by making a longitudinal incision along it. Entering
the deep surface of the cremaster is a small branch of the deep epigastric
artery and the genital branch of the genito-crural nerve. These constitute
its vascular and nervous supply, and must, if possible, be secured. Now
clean the transversalis muscle, and dissect out the vessels and nerves which
lie upon it.
Nerves of the Abdominal Wall. — Running forwards upon
the transversalis muscle, the dissector will find the following
nerves : —
1. The anterior portions of the lower I The anterior primary divisions
six intercostal nerves. of the lower seven dorsal
2. The last dorsal nerve. nerves.
3. The ilio-hypogastric nerve. \ From the anterior primary divi-
4. The ilioinguinal nerve. J sion of the first lumbar nerve.
The six lower intercostal nerves issue from the anterior ends
of the six lower intercostal spaces, and then proceed forwards,
between the internal oblique and transversalis muscles, to the
outer border of the rectus. Here they disappear by piercing
and passing within the sheath of this muscle. In a future
dissection they will be observed sinking into the substance of
1—24 h
374 ABDOMEN
the rectus, supplying it with twigs, and then turning forwards
to pierce the sheath a second time. They end on the front
of the abdomen as the anterior cutaneous nerves. Midway
between the spine and the linea alba they give off the late?-al
cutaneous nerves. They likewise supply offsets to the trans-
versalis and two oblique muscles. Minute arteries accom-
pany these nerves.
The last dorsal nerve has the same relation in the abdo-
minal wall as the preceding nerves. It gives off the same
branches, but in addition supplies a branch to the pyramidalis
muscle. Its lateral cutaneous or iliac branch, however, goes to
the skin of the buttock.
The ilio-hypogastric and ilio-inguinal are the two lowest
nerves of the series. They are directed forwards between
the internal oblique and the transversalis close to the crest of
the ilium.
The ilio-hypogastric is the higher of the two, and gives
off an iliac or lateral branch, which pierces the two oblique
muscles and then crosses the crest of the ilium to reach the
skin of the gluteal region. The hypogastric portioii of the
nerve perforates the internal oblique a short distance in front
of the anterior superior spine of the ilium, and then runs for-
wards towards the linea alba. It does not enter the sheath
of the rectus, and it becomes superficial by piercing the
aponeurosis of the external oblique immediately above the
external abdominal ring.
The ilio-inguinal nerve gives off no lateral branch. It
pierces the internal oblique, to which it gives branches, a
short distance above Poupart's ligament, and it becomes
superficial by passing through the external abdominal ring.
Transversalis Muscle (musculus transversus abdominis). —
This is the deepest of the three muscular strata which enter
into the formation of the wall of the abdomen. It has a
threefold origin — viz., from the pelvis, from the vertebral
column, and from the costal cartilages. By its pelvic origin
it is attached to the outer third of Poupart's ligament and to
the anterior two-thirds of the inner lip of the crest of the
ilium; by its costal origin it arises from the inner surfaces of
the costal cartilages of the lower six ribs by a series of slips
or digitations which interdigitate with the slips of origin of
the diaphragm ; by its ve?'tebral origin it is attached through
the medium of the lumbar fascia to the spinous processes,
ABDOMINAL WALL
375
transverse processes, and bodies of the lumbar vertebrae. In
point of fact, the lumbar fascia constitutes the posterior
aponeurosis of this muscle. But the manner in which this
fascia is attached to the vertebras requires further explanation.
As it approaches the spine it splits into three layers or
lamellae ; of these the posterior lamella is attached to the tips
of the spinous processes, the anterior lamella to the bodies of
the vertebrae at the roots of the transverse processes, and the
intermediate lamella to the tips and adjacent sides of the
transverse processes. Two aponeurotic compartments are
Fascia
transversali:
External
oblique
Internal
oblique
Transversal
Psoas
Quadratus
lumborum
Erector spinae
'
Serratus
post. inf.
ig. 141. — The dotted line represents the Peritoneum.
thus formed, the posterior of which is occupied by the erector
spinae, whilst in the anterior is placed the quadratus lum-
borum. These are points which cannot be demonstrated in
this dissection, but a reference to Fig. 141 will help the student
to understand the arrangement.
Anteriorly the fibres of the transversalis muscle end in
a strong aponeurosis, which is inserted into the linea alba, the
pubic crest, and the ilio-pectineal line. Towards this apo-
neurosis the fleshy fibres for the most part run in a transverse
direction. The lower fibres, however, take a curved course,
downwards and inwards, so that the muscle presents an arched
lower margin.
376
ABDOMEN
The dissector has already seen that the lower portions of
the aponeuroses of the internal oblique and the transversalis
Hypogastric
nerve
Cremaster.
Triangular
fascia
Superior
epigastric
Intercostal
nerve entering
sheath of
rectus
Sheath of rectus
External oblique
Internal
oblique
itercostal nerve
ransversalis
eep epigastric
unar fold of
glas
Fascia trans-
versalis
Internal
oblique
Rectus (cut)
Conjoined
tendon
Spermatic cord
Fig. 142. — Deep dissection of the Anterior Wall of the Abdomen. On the
left side the external oblique and the internal oblique have for the most
part been removed, the sheath of the rectus opened, and the greater
part of the contained muscle removed. On the right side the external
oblique, the upper part of the internal oblique, and the upper part of
the anterior wall of the sheath of the rectus have been removed.
muscles blend to form the conjoined tendon. It is through the
medium of this tendon that the transversalis gains its insertion
ABDOMINAL WALL 377
into the pubic crest and into the ilio-pectineal line. The
aponeurosis of the transversalis constitutes the greater portion
of the conjoined tendon — indeed, whereas the internal oblique
aponeurosis has an attachment to the ilio-pectineal line of
little more than half an inch, the aponeurosis of the trans-
versalis is fixed to fully an inch of this line.
Above the level of the conjoined tendon the aponeurosis
of the transversalis is inserted into the linea alba, but in
passing inwards to this insertion it presents two different
relations to the rectus muscle. Down to a point midway
between the umbilicus and pubes it passes behind the rectus,
and blends with the posterior lamella of the aponeurosis of
the internal oblique. Below this point it passes in front of
the rectus, and blends with the aponeuroses of the internal
oblique and external oblique.
Dissection. — The sheath of the rectus should now be opened on both
sides of the body by a vertical incision along the middle line of the muscle.
The divided anterior lamella should then be carefully raised from the
surface of the muscle and turned outwards and inwards. At the lines
transversa this can only be done with difficulty, so close is the connection
between the sheath and the tendinous intersections of the muscle.
Contents of the Sheath of the Rectus. — Within the rectal
sheath we find the following structures : —
1. The rectus muscle.
2. The pyramidalis muscle.
3. The terminal portions of the six lower intercostal nerves, and the
last dorsal nerve.
4. The deep epigastric artery.
5. The superior epigastric artery.
In cleaning the rectus keep in mind the intercostal nerves
and the last dorsal nerve. These will now be seen to enter
the sheath and sink into the rectus. After supplying it with
twigs, they come forward from its substance as the anterior
cutaneous nerves of the abdomen.
Rectus Muscle (musculus rectus abdominis). — This is
a broad band of muscular fibres whjch stretches between
the chest and the pubes, on each side of the linea alba.
Inferiorly it arises by two heads ; of these, the external and
larger is attached to the pubic crest, whilst the internal and
smaller is fixed to the ligaments in front of the symphysis
pubis (Fig. 61, p. 163). Towards the chest the muscle widens
and becomes thinner, and its insertion is effected by three large
378 ABDOMEN
slips into the anterior aspect of the costal cartilages of the
fifth, sixth, and seventh ribs.
The rectus muscle is broken up into portions by irregular
tendinous intersections — the inscriptiones tendinece or linea, trans-
versa. These are usually three in number, and are placed,
one at the level of the umbilicus, another opposite the ensiform
cartilage, and a third midway between. A fourth intersection
is sometimes found below the umbilicus. We have seen that
these tendinous intersections are closely adherent to the sheath
of the rectus in front. Raise the muscle, and it will be
apparent that they have no attachment to the sheath behind.
Pyramidalis Muscle. — This is a small triangular muscle —
not always present — which springs from the front of the pubes
and the ligaments of the symphysis, and is inserted into the
linea alba. It lies upon the lower part of the rectus, and
is supposed to act as a tensor of the linea alba.
The nerve of supply to the pyramidalis comes from the last dorsal nerve.
To bring it into view the muscle must be carefully detached from the linea
alba and turned downwards towards the pubes. The nerve will be exposed
entering its deep surface.
Sheath of the Rectus (vagina recti abdominis). — The
dissector is now in a position to study the manner in which
the rectal sheath is formed. An examination of the relations
which the aponeuroses of the three fiat muscles of the abdomen
bear to the rectus, will show that the sheath is incomplete, in
so far as the rectus is concerned. It is deficient posteriorly,
both above and below.
From the lower margin of the thorax to a point midway
between the umbilicus and pubes, it encloses the rectus upon
all sides. Here the anterior wall or lamella is formed by the
aponeurosis of the external oblique fused with the anterior
layer of the aponeurosis of the internal oblique, whilst the
posterior wall or la?nella is formed by the fusion of the posterior
layer of the aponeurosis of the internal oblique with the
aponeurosis of the transversalis (Fig. 141).
Superiorly, the rectus muscle rests directly upon the costa-
cartilages, and the sheath is merely represented by the apofr*
neurosis of the external oblique, which covers the muscle
anteriorly. Inferiorly, the posterior wall of the sheath is also
absent, and the rectus rests on the transversalis fascia. Here, '
however, the anterior wall is formed by a blending of all three
aponeuroses (Fig. 143).
ABDOMINAL WALL 379
The lower free margin of the posterior lamella of the
sheath can be easily defined by raising the rectus and working
with the handle of the knife. It usually presents a sharp
lunated edge, the concavity of which is directed downwards
.to the pubes. It is called the semilunar fold of Douglas (linea
semicircularis). The deep epigastric artery will be observed
to enter the sheath by passing upwards in front of this free
border (Fig. 142).
The semilunar fold of Douglas is often rendered indistinct
by the presence of scattered tendinous bundles crossing behind
the lower part of the rectus.
Linea Alba. — The linea alba can now be studied to the
best advantage. It is a dense fibrous cord or band which
extends perpendicularly between the ensiform cartilage and
the symphysis pubis. It is formed by the union and decussa-
tion of the fibres composing the aponeuroses of the two oblique
External oblique
Internal oblique
Transversalis
Fascia transveisalis
Fig. 143. — Transverse section through Abdominal Wall a short
distance above Pubis.
and the transversales muscles of opposite sides. Above the
umbilicus it is broad and band-like ; whilst below this point
it becomes narrow and linear. A close examination will show
that it is pierced by several small round openings for the
transmission of blood-vessels, and from some of these the
dissector may even observe minute fatty masses protruding.
A little below its middle is the umbilicus, but the foramen,
of which this is the remains, is now completely closed ;
indeed, in the adult the linea alba is stronger at this point
than elsewhere.
Fascia Transversalis. — This is a thin layer of fascia which
is spread out upon the deep surface of the transversalis muscle.
The fascia of one side is directly continuous with the fascia
of the opposite side, and it forms a part of an extensive fascial
stratum which lines the entire abdominal wall, and is placed
between the abdominal muscles and their aponeuroses on the
one hand, and the extra-peritoneal fatty tissue on the other.
Traced upwards, the fascia transversalis becomes thin, and
380 ABDOMEN
at the margin of the thorax it is directly continuous with the
fascia which lines the lower surface of the diaphragm. Towards
the inguinal region it plays an important part as a constituent
of the abdominal wall.
In the present state of the dissection (on the right side of
the body), a small gap or interval is seen to exist between
ANT1? SUPR SPINE OF
SPINE OF
PUBIS
CHMEIIT \ v,>«^
OF _ \
AT TAG
O
POUPART5 LIGT
Fig. 144. — Deep dissection of the Inguinal Region. The internal oblique has
been reflected to show the whole length of' the inguinal canal, and the
cord enclosed within the infundibuliform fascia is seen cut across.
the lower arched border of the transversalis muscle and
Poupart's ligament.' The membrane which fills up this
interval is the transversalis fascia. At no part of the
abdominal wall is the fascia stronger than here, and this
accession of strength is obviously for the purpose of com-
pensating for the deficiency in the internal oblique and trans-
versalis muscles, which, at this point, do not descend so low
as Poupart's ligament. In this interval the transversalis fascia
ABDOMINAL WALL 381
has an important relation to the spermatic cord. Here the
fascia is pierced by the cord, but as yet no opening is visible.
Take hold of the cord and draw it downwards and inwards.
The margins of the aperture through which it passes will be
observed to be prolonged downwards upon the cord in a
funnel-shaped manner, so as to invest it upon all sides with a
tube of fascia. This investment, which is thus seen to come
directly from the fascia transversalis, is called the infundibuli-
form or internal spermatic fascia.
Dissection. — It must now become the object of the dissector to
demonstrate the more important attachments of this fascia. For this
purpose divide the fibres of the transversalis muscle along the outer part
of Poupart's ligament and along the crest of the ilium, and, raising the
muscle from the subjacent fascia, throw it upwards. It is not necessary to
reflect the entire muscle.
Attachments of the Fascia Transversalis. — When the fascia
is cleaned with the handle of the scalpel, it will be seen to be
attached laterally to the inner lip of the iliac crest. Along
the line of this attachment, which is by no means firm, it
becomes continuous with the fascia iliaca — that portion of the
same fascial stratum which covers the iliacus and psoas
muscles in the iliac fossa. Close to the crest of the ilium the
fascia transversalis is pierced first by the ascending branch and
then by the terminal branches of the deep circumflex iliac
artery. In front, in the inguinal region, its connections are
more complicated, and must be studied at three different
points — (1) between the anterior superior iliac spine and the
femoral artery, where it will be seen to be attached to Poupart's
ligament ; along this line also it becomes continuous with the
fascia iliaca; (2) opposite the femoral vessels, where it is
carried downwards into the thigh behind Poupart's ligament,
to form the anterior part of the femoral or crural sheath {vide
p. 203) ; (3) internal to the femoral vessels, where it is attached
to the ilio-pectineal line and the pubic bone, behind the con-
joined tendon, with which it is partially blended.
Internal Abdominal Ring (annulus inguinalis abdominalis).
— We have seen that the transversalis fascia is pierced by the
spermatic cord. The opening through which it passes is called
the internal abdominal ring. This opening can only be defined
from the front by an artificial dissection — viz., by dividing the
infundibuliform fascia around the cord, and pushing it upwards
with the handle of the knife. The ring thus defined will be
382 ABDOMEN
observed to lie about half an inch above Poupart's ligament, at
a point midway between the symphysis pubis and the anterior
superior spine of the ilium. Through the opening the dissector
can see the extra-peritoneal fat upon which the transversalis
fascia rests, and immediately internal to the opening he will
notice the deep epigastric artery, pursuing its oblique course
upwards and inwards, and shining through the fascia. If the
handle of the knife be now introduced into the ring and carried
outwards between the fascia and extra-peritoneal fat, the
attachments of the fascia to Poupart's ligament and to the
iliac crest can be very clearly shown.
Canalis inguinalis. — The dissector has observed that the
spermatic cord in the male and the round ligament in the
female pierces the abdominal wall above Poupart's ligament.
The passage which is formed for their transmission receives
the name of the inguinal canal. Now, as this canal is a source
of weakness to the abdominal wall, and as it is in connection
with it that inguinal hernia occurs, the student will understand
how necessary it is that he should examine it carefully from
all points of view.
The inguinal canal is a narrow channel of about one inch
and a half in length. It begins at the internal abdominal
ring, which may be spoken of as its inlet, and ends at the
external abdominal ring, which constitutes its outlet. It is,
consequently, very oblique, having a direction almost directly
inwards, with a slight inclination downwards and forwards.
So much for its length and direction ; we have still to make
out in connection with it (i) a floor; (2) an anterior wall;
and (3) a posterior wall.
The floor is formed in the first part of the canal by the
upper grooved surface of Poupart's ligament. Towards the
outlet, however, the floor becomes broader and more definite ;
here it is formed not only by Poupart's ligament, but also by
Gimbernat's ligament. At this point, as the student has
already observed, the cord rests directly upon the abdominal
surface of the latter ligament. The parts which enter into
the formation of the anterior wall axe — (1) the aponeurosis of
the external oblique throughout the entire extent of the canal ;
and (2) the lower border of the internal oblique in the outer
third of the canal. These facts can be readily verified by
restoring the structures to their original positions. The parts
which compose the posterior wall are still in situ. Naming
ABDOMINAL WALL 383
them in order, from the inlet to the outlet, they are — (1) the
fascia transversalis ; (2) the conjoined tendon; and (3) the
triangular fascia, when it is strongly developed.
But it may be asked, Does the transversalis muscle take no
part in the formation of the inguinal canal ? The student
can readily satisfy himself as to this point. He will notice
that the arched lower border of this muscle does not descend
so low as that of the internal oblique, that, in fact, it stops
short immediately above the internal abdominal ring. The
canal is closed superiorly by the approximation of the anterior
and posterior walls above the cord and by the intervention
between these walls of the lower border of the transversalis.
There is still another point to be noted, viz., the relation
which the deep epigastric artery bears to the posterior wall of
the canal. This vessel can be felt (and, indeed, in most
cases seen) extending obliquely upwards and inwards, behind
the transversalis fascia, to the outer border of the rectus. A
triangular space is thus mapped out by the artery, Poupart's
ligament, and the outer border of the rectus. This receives
the name of the triangle of Hesselbach. The floor of the space
is formed by the posterior wall of the inguinal canal, and
chiefly by that part of it which is composed of the conjoined
tendon.
In the female the inguinal canal is much smaller than in
the male. It has the same boundaries, and it is traversed
by the round ligament of the uterus.
Arteries of the Abdominal Wall. — In the abdominal wall
we find the following arteries : —
1. The intercostal and lumbar arteries.
2. The deep epigastric.
3. The deep circumflex iliac.
4. The superior epigastric.
5. The musculo-phrenic.
The intercostal arteries of the three lower spaces are pro-
longed forwards between the internal oblique and the trans-
versalis. They have already been noted accompanying the
corresponding nerves. In front they anastomose with the
epigastric arteries, whilst inferiorly they effect communications
with the lumbar arteries.
The abdominal branches of the lumbar arteries ramify between
the same two muscles as the preceding vessels, but at a lower
level in the abdominal wall. Anteriorly they anastomose with
384 ABDOMEN
the deep epigastric artery ; above with the intercostal arteries ;
and below with the deep circumflex iliac and the ilio-lumbar.
Deep Epigastric Artery (arteria epigastrica inferior). — This,
a branch of the external iliac, is a vessel of some size, and takes
origin about a quarter of an inch above Poupart's ligament.
At present it is seen shining through the fascia transversalis
and forming the outer boundary of Hesselbach's triangle.
Divide the fascia transversalis along its course and it will be
observed to be accompanied by two veins. Study the course
and relations of this vessel. At first it runs inwards for a
short distance between Poupart's ligament and the internal
abdominal ring, and then changing its direction it is carried
upwards and inwards on the inner side of the ring. Reaching
the deep surface of the rectus it enters the rectal sheath, and
proceeding vertically upwards, ends near the lower margin of
the thorax in branches which sink into the substance of the
muscle and anastomose with the superior epigastric and the
intercostal arteries.
In the first part of its course, the deep epigastric lies in the
extra -peritoneal fat between the peritoneum and the fascia
transversalis. It soon, however, pierces the fascia, and, passing
in front of the fold of Douglas, ascends between the rectus
muscle and the posterior lamella of its sheath. These are
its immediate relations, but there are others of equal importance,
viz., (i)as it runs upwards it lies close to the inner side of the
internal abdominal ring; (2) as the spermatic cord traverses
the inguinal canal it lies in front of the artery, only separated
from it by transversalis fascia; (3) as the vas deferens passes
from the inguinal canal into the abdominal cavity it hooks
round the outer side of the artery.
The branches which spring from the deep epigastric are —
1. Cremasteric.
2. Pubic.
3. Cutaneous.
4. Muscular.
The cremasteric is a small twig which supplies the cremaster
muscle and anastomoses with the spermatic artery. The pubic,
also insignificant in size, goes to the back of the pubes,
where it anastomoses with a small branch from the obturator.
The importance of this branch arises from the fact that the
anastomosis which it establishes sometimes becomes so large
as to take the place of the obturator artery. The muscular
ABDOMINAL WALL 385
branches are given to the substance of the rectus, and the
cutaneous offsets pierce the abdominal muscles and anastomose
with the superficial epigastric artery.
Deep Circumflex Iliac (arteria circumflexa ilii profunda). —
This vessel springs from the outer side of the external iliac
artery, about the same level as the deep epigastric, and runs
outwards behind Poupart's ligament to the anterior superior
spine of the ilium. From this point onwards it takes the
crest of the ilium as its guide, and ends by anastomosing
with the ilio-lumbar artery. At first it is placed in the extra-
peritoneal fat, and consequently it lies between the fascia
transversalis and the peritoneum. Its course behind Poupart's
ligament is indicated by a whitish line, which marks the union
of the fascia transversalis and fascia iliaca ; and if the former
fascia be now divided along this line, the deep circumflex iliac
will be exposed. At the crest of the ilium the vessel pierces
the fascia transversalis, and lies between this and the trans-
versalis muscle \ and lastly, about the middle point of the
iliac crest it pierces the transversalis muscle, and its terminal
twigs ramify between it and the internal oblique. In this
manner, then, the artery gradually approaches the surface as
we trace it from its origin to its termination, and its relations
may be expressed thus : —
1. Between fascia transversalis and peritoneum.
2. Between fascia transversalis and transversalis muscle.
3. Between transversalis muscle and internal oblique muscle.
The dissector has already seen the ascending branch which
it sends upwards between the internal oblique and transversalis
muscles.
Superior Epigastric and Musculo-phrenic Arteries. — These
are the two terminal branches of the internal mammary.
The superior epigastric (arteria epigastrica superior) will be
found behind the rectus muscle and within the upper part of
its sheath. It gives twigs to the rectus, and anastomoses
with the deep epigastric.
The musculo-phrenic (arteria musculophrenica) can only be
seen by reflecting the transversalis from the ribs. It will be
found at the level of the eighth rib. From this it proceeds
downwards and backwards, along the attachment of the
diaphragm, to the last intercostal space. It gives branches
to the diaphragm and others (the anterior intercostals), which
enter the lower intercostal spaces.
vol. 1 — 25
386 ABDOMEN
Dissection. — When the transversalis fascia is reflected the only layers
which intervene between the dissector and the abdominal cavity are the
extra-peritoneal fatty tissue and the parietal peritoneum.
If the subject be a male, now is the best time for the student to examine
the constitution of the scrotum, spermatic cord, and testicle. This can
only be done at present on the right side, as the parts on the opposite side
must be kept in situ for the study of hernia. After this, however, the
dissection can be repeated on the left side.
The dissector works at a great disadvantage when he attempts to unfold
the coverings of the cord and unravel its constituent parts while they are
attached to the body. The cord and testicle of the right side should be
removed by dividing the former with its coverings at the level of the
external abdominal ring. The specimen should then be placed in a cork-
lined tray and dissected under water. Having fastened the cord and
testicle with pins to the bottom of the tray, little difficulty will be
experienced in displaying and recognising the different layers, and a
splendid demonstration will be afforded of the constituent parts of the cord.
Scrotum. — This is a pendulous purse-like arrangement of
the skin and superficial fascia for the lodgment of the testicles.
The skin composing it is of a dark colour and rugose, and is
traversed along the middle line by a median raphe or ridge,
an indication of its bilateral character.
When the skin is removed the superficial fascia is observed
to possess certain characters peculiar to itself. It has a
ruddy colour, and is totally devoid of fat. The ruddy tint is
due to the presence of involuntary muscular fibres, which
take the place of the fat, and constitute what is called the
dartos muscle. The rugosity of the scrotal skin is maintained
by these muscular fibres. But further, the superficial fascia
forms in the interior of the scrotum an imperfect septum or
partition, which divides it into two chambers — one for each
testicle. These points in connection with the construction
of the scrotum have all, to a certain degree, been noted in
the dissection of the perineum.
But these two scrotal tunics are not the only coverings of
the testicle. Each constituent of the abdominal wall has
been seen to contribute an investment to the spermatic cord,
and these in turn are continued down so as to clothe the
testicle. Presuming, then, that the skin and superficial fascia
are reflected, the testicle and cord within the scrotum will
still be found to be invested by —
1. The external spermatic or intercolumnar fascia from the
aponeurosis of the external oblique.
2. The cremasteric fascia — the muscular element of which is partly
derived from the internal oblique.
T,. The infundibuliform fascia from the fascia transversalis.
SPERMATIC CORD 387
The dissector will find it difficult to demonstrate in every case these
different investments of the testicle. In cases of large hernia? of old
standing, however, they become thickened, and are more readily
recognisable.
From the above description the student will understand
that there is only one tunic common to both testicles — viz.,
the integument ; that the superficial fascia and dartos, and
the investments derived from the abdominal wall, constitute
special tunics for each testicle.
Spermatic Cord. — The spermatic cord is formed by the
association together of certain blood-vessels, nerves, and
lymphatics, along with the vas deferens, all of which are
proceeding to or coming from the testicle. These structures
come together at the internal abdominal ring, and this may
be taken as the point at which the cord begins. It has
already been traced in its course through the inguinal canal,
and has been observed to issue from it through the external
abdominal ring. It is now seen as it lies within the scrotum
suspending the testicle.
Before dissecting out the constituent parts of the cord,
examine the extra-peritoneal fatty tissue which lies behind
the internal abdominal ring. Note that a process of this
tissue is prolonged downwards with the cord. Now with
the handle of the knife gently separate the extra-peritoneal
fat from the subjacent peritoneum. Behind the internal
abdominal ring the peritoneum shows a slight bulging
forwards, and a slender fibrous band may be detected
passing into the cord from the most prominent part of this
bulging. This fibrous cord is the remains of the tube of
peritoneum, which in the foetus connected the serous invest-
ment of the testicle (the tunica vaginalis) with the general
peritoneal lining of the abdomen. In some cases it may be
traced as far as the testicle, but more commonly it only
extends down the cord for a short distance ; indeed it is
frequently absent.
To obtain a proper conception of this fibrous thread, it is necessary that
the student should understand that the testicle is not developed within the
scrotum. Up to a comparatively late period of intra-uterine life the testicle
is situated within the cavity of the abdomen. It lies upon the psoas
muscle, immediately below the kidney, and is not only invested by
peritoneum, but is connected to the posterior wall of the abdomen by a
short fold of that membrane, which receives the name of the mesorchium.
As development proceeds, the testicle gradually descends on the posterior
wall of the abdomen. It retains its peritoneal investment, and in the
388
ABDOMEN
seventh month it reaches the internal abdominal ring. Prior to its entrance
into the inguinal canal, a test-tube-like process of peritoneum, termed the
processus vaginalis, is carried into the passage (Fig. 145, A.). The testicle
with its peritoneal covering enters this tubular recess, and during the eighth
month it traverses the inguinal canal. Finally, towards the end of the
ninth month, it reaches the bottom of the scrotum (Fig. 145, B. ). Through-
out the whole journey it is preceded by the processus vaginalis, which, as
it were, prepares the way for it.
The testicle, therefore, in. its descent has a double relation to the
A.
T.V:
T.V.
Fig. 145. — Diagrams illustrating the descent of the
testicle and the derivation of the tunica vaginalis from the
peritoneal lining of the abdominal cavity. The inguinal
canal is represented by a ring.
P. Peritoneum. P.V. Processus vaginalis.
T. Testicle. T.V. Tunica vaginalis.
S. Scrotum F.C. Fibrous cord or thread.
peritoneum — viz., (1) it carries with it into the scrotum its own proper
investment ; (2) it is preceded in its passage into the inguinal canal and
the scrotum by a tubular prolongation of the parietal peritoneum, which
forms a diverticulum of the general peritoneal sac within the scrotum. In
those quadrupeds in which the testicle reaches the scrotum, this diverticulum
or processus vaginalis remains open, and freely communicates with the
abdominal cavity. In man, the lower part of the diverticulum which holds
the testicle is alone retained ; the upper part is obliterated, and no trace is
left, beyond, perhaps, the fibrous cord mentioned above. In this manner,
then, the tunica vaginalis of the testicle is formed, the original peritoneal
investment remaining as the visceral or testicular part, and the lower part
of the processus vaginalis being retained as the parietal or scrotal part (see
description of tunica vaginalis, p. 391).
The orifice by which the abdominal peritoneal cavity communicates
SPERMATIC CORD 3S9
with the scrotal peritonea! diverticulum is usually closed before birth
(Fig. 145, C. ), and the upper part of the processus vaginalis, from the
internal abdominal ring to the upper end of the testicle, is generally
obliterated in the first month of extra-uterine life (Fig. 145, D. ).
The gubemaculum testis is the active agent in bringing about the
descent of the testicle. This is a band of involuntary muscular fibres
which traverses the inguinal canal, and establishes important connections
both within and without the abdominal cavity. Below, three main
attachments of the gubemaculum may be recognised — viz., {a) to the
abdominal wall ; (b) to the pubis ; (c) to the bottom of the scrotum.
Above, the gubernacular fibres are chiefly connected with the testicle ; but
many of them are also attached to the peritoneum on the posterior wall of
the abdomen. By the traction which the gubemaculum exerts on the
testicle the descent of that organ is brought about. By the portion attached
to the abdominal wall the testicle is pulled down to the internal abdominal
ring, the pubic portion drags it through the inguinal canal, whilst the
scrotal part finally leads it into the scrotum.
The formation of the processus vaginalis is accounted for in the same
way. Some of those gubernacular fibres which are inserted into the
peritoneum drag down the peritoneal diverticulum which lines the inguinal
canal and scrotum, and prepares the way for the testicle.
It is but right to state that the active part we have ascribed to the
gubemaculum in the process of testicular descent is not admitted by all
anatomists. There are many who deny that it exerts any active traction
upon the testicle. They consider that through the gubemaculum failing to
keep pace with the general growth of surrounding parts, it anchors the
testicle to a particular level, and by this means finally lands it in the
scrotum.
Dissection. — The coverings of the spermatic cord should now be
removed, and the parts which enter into its formation isolated from each
other.
Constituent Parts of the Spermatic Cord. — The following
are the structures which form the spermatic cord : —
1. The vas deferens.
I (The spermatic.
2. Blood-vessels. \ Arteries- j ™e ^masteric.
^ I he artery to the vas deferens.
I Veins. The spermatic plexus of veins.
3. Lymphatics.
Nerves /Genital branch of the genito-crural.
(Sympathetic twigs.
These are all held together by loose areolar tissue which
intervenes between them, and also by the investments which
are given to the cord by the abdominal wall.
The cremasteric artery is a branch of the deep epigastric,
and has already been seen entering the cremaster muscle.
The getiital branch of the genito-crural nerve has a similar
destination. It has also been displayed in a previous stage
of the dissection.
1— 25 «
39°
ABDOMEN
JLL|iJ— Artery to vas
Spermatic artery
Vas
Pampiniform
plexus
The spermatic artery arises within the abdomen from the
front of the aorta, and entering the cord at the internal
abdominal ring, proceeds to the testicle, into the posterior
border of which it sinks, after dividing into several smaller
twigs. The spermatic veins issue from the testicle at its
posterior border, and as they pass upwards they form in the
cord a bulky plexus, which is termed the sper?natic or pampini-
form plexus. A single vessel
issues from this, which enters
the abdomen through the
internal abdominal ring. On
the right side it pours its
blood into the inferior vena
cava ; on the left side it joins
the left renal vein.
The vas deferens (ductus
deferens), the duct of the
testicle, can always be dis-
tinguished by the hard, firm,
cord-like sensation which it
gives when the spermatic
cord isheldbetweenthefinger
and thumb. It ascends along
the posterior part of the cord.
At the internal abdominal
ring, however, it separates
from the spermatic vessels,
and lies to their inner side,
and as it enters the abdomen
it hooks round the deep
epigastric artery.
The artery to the vas de-
ferens is a small branch from the superior vesical. It follows
the duct to the testicle.
The sy?npathetic filaments extend downwards upon the
spermatic artery. They come from the renal and aortic
plexuses.
The spermatic lymphatics enter the abdomen through the
internal abdominal ring, and join the lumbar glands.
Testicle (testis). — The testicle should next be examined.
First note its position in the scrotum. It lies somewhat
obliquely, with its upper end directed forwards and outwards,
Globus major
Digital fossa
Body of epi-
didymis
Testis
Globus minor
Fig. 146. — Dissection of the Left Sper-
matic Cord to show its constituent
parts. (From Waldeyer, modified.)
TESTICLE
391
and its lower end backwards and inwards. The left testicle
hangs at a lower level than the right.
Each testicle is enveloped by the tunica vaginalis testis.
The tunica vaginalis is a serous sac, and consequently pre-
sents a parietal or scrotal portion, and a visceral or testicular
portion. Its extent can be demonstrated in a striking
manner by making a small aperture in the parietal part, and
Skin
Dartos
Ext. spermatic fasci
Cremasteric fascia--—
Infundibuliform
fascia
Parietal tunic:.
vaginalis
Visceral tunica
vaginalis / l/M"?
Tunica albuginea -['"pa
A lobule of the '
testicle
A septum
Mediastinum
Digital fossa
Spermatic vein
Epididymis
Vas deferens...
Artery to vas
Spermatic artery
Internal muscular
tunic of Kolliker
Fig. 147. — Transverse section through the left side of the
Scrotum and the Left Testicle. The sac of the tunica vaginalis
represented in a distended condition.
then introducing a blow-pipe into the serous cavity and inflat-
ing it with air. It will be seen to be considerably larger than
the gland which it envelops. It ascends for some distance
upon the spermatic cord, and it even descends beyond the
testicle. When flaccid, the parietal part is simply wrapped
loosely over the visceral portion which adheres to the surface
of the testicle.
Dissection. — Open into the sac of the tunica vaginalis by running a pair
of scissors along the anterior aspect of the parietal part. On folding back
the parietal portion of the tunica vaginalis the form of the testicle may be
studied, and also the manner in which it is clothed by the visceral layer.
1—2.". b
392
ABDOMEN
Body and Epididymis of the Testicle. — The testicle is an
oval body, with flattened sides. The posterior border is also
somewhat flattened, and here we see the epididymis. This is an
elongated and arched structure, which is adapted to the upper
end and outer side of the posterior border of the testicle. The
upper end of the epididymis is enlarged, and is termed the
(;v.
Fig. 148.
The Right Testis and Epididymis
within the tunica vaginalis. (A. F.
Dixon. )
s.c. Spermatic cord.
g.m. Globus major.
c. Body of epididymis.
t. Testis.
//. Hydatids of Morgagni.
t.v. Tunica vaginalis.
B. The Right Testis and Epi-
didymis seen from behind,
after removal of the parietal
part of the tunica vaginalis.
(A. F. Dixon.)
t.v'. Cut edge of tunica vaginalis
along the line where the
parietal part becomes con-
tinuous with the visceral
part.
v.d. Vas deferens.
g.m' . Globus minor.
globus major (caput epididymis) ; its lower end is called the
globus minor (cauda epididymis); while the intervening portion,
which is narrow, receives the name of the body of the epididymis
(corpus epididymis). The globus major is attached to the
upper end of the testicle, which it surmounts like a helmet,
not only by the visceral tunica vaginalis which is continued
over it, but also by the vasa efferentia, which pass from the
TESTICLE 393
one into the other. The globus minor is merely fixed to the
back of the testicle by the visceral tunica vaginalis and some
intervening areolar tissue, whilst the body of the epididymis is
free, and is separated from the body of the testicle by an
involution of the serous covering which forms the digital fossa.
If the upper end of the body of the testis be carefully
examined, two minute structures will be observed attached
to it close to the globus major. These are the "hydatids of
Morgagni" remnants of an embryonic canal called Miillers
duct. One of the hydatids is usually pear-shaped and
stalked ; the other is smaller and generally sessile.
The vas deferens emerges from the lower end of the globus
minor, and then passes upwards upon the posterior border of
the testicle on the inner side of the epididymis. By this
relation, the side to which a given testicle belongs can be
readily detected. The vessels have already been seen enter-
ing and emerging from the posterior border of the testicle.
Visceral Layer of the Tunica Vaginalis Testis. — Having
learned the foregoing points concerning the testicle, the
student is in a position to trace the visceral layer of the tunica
vaginalis upon its surface. Observe that it envelops it closely
on every side, with the exception of the posterior border,
where the vessels enter and emerge. The posterior aspect of
the epididymis is also, to a certain extent, left bare. On the
outer surface of the organ it forms a little cul-de-sac between
the body of the epididymis and the body of the testicle.
This is called the digital fossa. Xote particularly that it is
along the posterior border of the testicle that the parietal
part of the tunica vaginalis becomes continuous with the
visceral part.
Dissection. — Some of the main facts relating to the structure of the
testicle may be learned by a careful naked-eye examination of its different
parts. For this purpose place it in a cork-lined tray and dissect it under
water. Having fixed it with pins to the bottom of the tray, begin by
tracing the vessels into the gland. In doing this a quantity of involuntary
muscular tissue spread over the posterior border of the testicle and the
epididymis becomes apparent. This is the inner muscular tunic of
Kolliker. The intimate manner in which the visceral tunica vaginalis
clings to the surface of the testis should next be ascertained by endeavouring
to raise it as a distinct layer. Remove now the parietal tunica vaginalis
and free the globus minor and body of the epididymis from the back of the
gland. This can be easily done by cutting the serous covering as it pa-
from one to the other, and breaking through the fibrous tissue which
intervenes between the globus minor and the lower part of the body of the
testis. Do not interfere with the globus major. Turning the epididymis
394 ABDOMEN
aside, the body of the gland may be divided transversely with a sharp knife
about its middle into an upper and a lower portion.
Structure of the Testicle. — The cut surface of the lower
part of the body of the testis may now be studied. The
dense, tough fibrous coat which envelops it under cover of
the visceral tunica vaginalis first attracts attention. It is
called the tunica albuginea. At the posterior border of the
gland it will be seen to be projected into the interior in the
form of a thick fibrous elevation. This extends along the
whole length of the posterior border, and receives the name
of the mediastinum testis (corpus Highmori). It is traversed
by the vessels that pass into and out from the gland, and
it is also tunnelled by a plexus of seminal canals, called the
rete testis.
From the front and sides of the mediastinum testis radiat-
ing fibrous lines will be seen passing into the substance of
the testis. These are the cut margins of incomplete fibrous
lamellae or septa which extend towards the deep surface of
the tunica albuginea and become connected with it (Fig. 147).
By means of these partitions and the mediastinum testis, the
space enclosed by the tunica albuginea becomes broken up
into a large number of loculi or compartments, the walls of
which are imperfect. Such is the fibrous framework of the
body of the testicle.
The blood-vessels have a very definite arrangement with
reference to this framework. Passing in through the media-
stinum they spread out on the deep surface of the tunica
albuginea, and upon both surfaces of the fibrous lamellae
which bound the testicular compartments. The vascular
mesh-work thus formed is sometimes called the tunica
vasculosa.
The proper glandular substance of the testis is lodged
within the compartments described above. It consists of an
enormous number of fine hair-like tubes, termed the seminiferous
tubules. Two or more occupy each compartment, and con-
stitute what is called a testicular lobule (lobulus testis). In
this they are closely packed and are coiled and convoluted
to an extraordinary degree. The dissector should now
endeavour to unravel some of these tubuli seminiferi under
water. It wrill be impossible to open them out in their whole
length, but a sufficiently good demonstration may be obtained
to make their general arrangement apparent. The length
TESTICLE
395
of these tubes is remarkable. Thev average two feet in
length.
Approaching the mediastinum testis the tubuli seminiferi
join each other at acute angles and form a smaller number of
tubes, which finally become straight and considerably reduced
in diameter. These are called the tubuli recti. They enter
the mediastinum and join the rete testis.
Dissection. — The tubuli seminiferi should now be removed from the lower
part of the gland. This can be done with the forceps under a stream of
water. A good view is then obtained
of the fibrous framework of the testicle.
The strength of the tunica albuginea
becomes evident, whilst the media-
stinum testis and the lamellce which
proceed from it are seen to great
advantage.
The dissector must next endeavour
to ascertain the manner in which the
secretion of the testicle passes from
the rete testis into the epididymis.
For this purpose the upper part of the
testicle with the attached epididymis
must be examined. Gently raise the
globus major from the surface of the
body of the testis by dividing the
visceral part of the tunica vaginalis
which binds them together, and care-
fully break down the intervening Fig. 149.-
-Diasrram illustrating the
connective tissue. Under favourable
circumstances the rasa efferentia may
be seen.
Structure of the Testicle.
Dixon. )
(A. F.
v.d. Vas deferens.
fr.nf. Globus minor.
c. Globus major.
c.v. Coni vasculosi.
v.e. Yasa efferentia.
V.r. Tubuli recti.
r.v. Rete testis.
s.t. Seminiferous tubule.
j. Septula testis
Structure of the Epididymis.
— The vasa efferentia (ductuli
efferentes testis) are fifteen to
twenty delicate ducts which
leave the upper part of the rete
testis, pierce the tunica al-
buginea, and pass into the
globus major. In this body the vasa efferentia become
coiled and form a series of small conical masses, called
the ami vasculosi. Ultimately these ducts open into a single
convoluted canal, termed the canal of the epididymis (ductus
epididymis). The globus major is thus composed of the
coni vasculosi and the coiled canal of the epididymis. The
body and globus minor of the epididymis are formed of
the continuation of the same canal coiled and convoluted
upon itself to a remarkable degree.
396 ABDOMEN
The intricacy of its flexuosities will be better understood by
simply stating that if it were completely opened out it would
be found to measure twenty feet or more. At the lower end
of the globus minor the canal of the epididymis becomes con-
tinuous with the vas deferens.
Dissection. — The dissector should endeavour to unravel a part of the
canal of the epididymis. The coils are held together by areolar tissue and
the dissection is very tedious.
Surgical Anatomy. — To the surgeon the anatomy of the abdominal
wall presents a very special interest from the bearing which it has upon
Hernia or Rupture.
Hernia abdominis may be defined as being the protrusion of any viscus
or portion of a viscus, or the protrusion of any portion of a peritoneal fold
{e.g., great omentum) through the wall of the abdomen. There are three
localities in which, from natural weakness of the parietes, this protrusion
is specially liable to occur — ( I ) through the external abdominal ring, which
gives passage to the spermatic cord in the male, and the round ligament of
the uterus in the female ; (2) through the crural canal or innermost
compartment of the femoral sheath, within which certain lymphatic vessels
ascend from the thigh into the abdominal cavity ; (3) through the umbilicus
or the foramen in the linea alba of the fcetus, which transmits the con-
stituents of the umbilical cord. These different forms of hernia are
distinguished by the terms — inguinal, femoral, and umbilical.
There are other situations at which hernial protrusions occur, but so
rarely that it would be out of place to take notice of them here.
Inguinal Hernia. — The inguinal canal is not so great a source of
weakness to the abdominal wall as might, at first sight, be expected, and
this chiefly on account of its obliquity of direction. The inlet or internal
abdominal ring is situated a long way (fully an inch and a half) to the outer
side of the outlet or external abdominal ring. The canal is therefore
distinctly valvular ; the greater the force with which the viscera are pressed
directly against the inguinal part of the abdominal parietes, the more firmly
will the posterior wall of the canal be pressed against the spermatic cord
and the anterior wall.
On the left side of the body the parts related to inguinal hernia have
been retained in position. The student should, therefore, make a dissection
of the inguinal region, with special reference to hernia. Begin by reflecting
the aponeurosis of the external oblique. Make a vertical incision through
it parallel to the outer border of the rectus, and carry it downwards on
the inner side of the internal pillar of the external abdominal ring. The
aponeurosis can thus be thrown downwards and outwards, and the external
ring, at the same time, preserved. The internal oblique, cremaster, and
conjoined tendon should now be cleaned, and their precise relations to the
spermatic cord studied. Notice that the fleshy lower border of the internal
oblique overlaps the upper part of the cord, whilst, towards the outlet of
the inguinal canal, the conjoined tendon lies behind the cord. Next replace
the aponeurosis of the external oblique, and, introducing the point of the
forefinger into the external abdominal ring, press directly backwards.
Observe that it rests upon the conjoined tendon ; that, in fact, this tendon
and the fascia transversalis alone intervene between the finger and the
extra-peritoneal fatty tissue and the peritoneum. The lower part of the
internal oblique muscle should now be separated from the transversalis by
insinuating the handle of the knife between them. When this is done,
EPIDIDYMIS 397
divide the internal oblique close to Poupart's ligament, and throw it
forwards. At the same time, make a longitudinal incision through the
cremaster muscle, and turn it aside from the surface of the cord.
All further dissection must be effected from the inside. Divide the
abdominal wall horizontally, from side to side, at the level of the umbilicus.
When the lower part of the abdominal wall is raised, the student will
observe on its posterior aspect three peritoneal ridges or falciform folds
radiating from the umbilicus as from a centre, and proceeding downwards
towards the brim of the pelvis. These are caused by the presence of three
fibrous cords, — the urachus and the two obliterated hypogastric arteries, —
in the extra-peritoneal fatty tissue. The urachus occupies the middle line,
and extends downwards to the apex of the bladder. The obliterated
hypogastric artery proceeds downwards and outwards on each side so as to
gain the side of the bladder when this is distended, or the lateral wall of
the pelvis when it is empty. On the posterior aspect of the anterior wall of
the abdomen it lies a short distance to the inner side of the internal
abdominal ring.
There is still another peritoneal ridge or fold on this aspect of the
abdominal wall. It is formed by the deep epigastric artery as it passes
upwards and inwards to reach the deep surface of the rectus abdominis
muscle. It is placed a short distance to the outer side of the fold which
corresponds to the obliterated hypogastric artery, and runs more or less
parallel to it.
By these three peritoneal folds three fossae, which vary greatly in depth
in different subjects, are formed on either side of the middle line close to
Pouparts ligament. They are termed the external, middle, and internal
inguinal pouches, and are very generally regarded as determining, to a
certain extent, hernial protrusions in this region. The internal inguinal
fossa lies between the folds formed by the urachus and the obliterated
hypogastric arteries, and the external abdominal ring or the outlet of the
inguinal canal corresponds to its outer and deepest part. The middle
inguinal fossa, very narrow but frequently very deep, is situated between
the peritoneal folds which enclose the obliterated hypogastric artery and the
deep epigastric arteries. The bottom of this fossa corresponds to the outer
part of the posterior wall of the inguinal canal, or, in other words, to that
part of the posterior wall which is formed by the fascia transversalis. The
external inguinal fossa is placed to the outer side of the deep epigastric
artery, and its lower, inner, and deepest part corresponds to the internal
abdominal ring.
The student has already seen, in the dissection of the abdominal wall,
that the deep epigastric artery, together with Poupart's ligament and the
outer border of the rectus, bound a triangular space termed Hesselbach's
triangle. Recalling this fact, he will understand that the obliterated
hypogastric artery, which lies to the inner side of the deep epigastric, must
ascend in relation to the posterior aspect of the floor of the triangle and cut
the space into two.
Having determined these points, the dissector can proceed as follows : —
Divide the lower part of the abdominal wall in a vertical direction along the
linea alba, from the umbilicus to the pubes. Make this incision a little on
one side of the urachus, and, on nearing the pubic symphysis, be careful not
to injure the bladder, which may project upwards beyond it. On throwing
the left flap downwards and outwards, it may be possible to detect the
position of the internal abdominal ring from the fact that in some cases the
peritoneum is slightly dimpled into it. This dimple or depression is termed
the digital fossa. Now strip the peritoneum from the flap as far down as
Poupart's ligament. This can be easily done with the fingers, as its
398 ABDOMEN
connection with the extra-peritoneal fatty tissue is very slight. Next
separate the extra -peritoneal fatty tissue from the fascia transversalis
with the handle of the knife, proceeding with great care as Poupart's
ligament is approached. The internal abdominal ring, or the inlet of the
inguinal canal, is now seen from within. From this point of view the
opening is more like a vertical slit in the fascia transversalis than a ring.
Its lower and external margin will be seen to be specially strong and thick.
Note the deep epigastric artery passing upwards and inwards close to its
inner margin. Further, observe the vas deferens and the spermatic vessels
entering it, the former, as it disappears into the canal, hooking round the
deep epigastric artery. Introduce the tip of the little finger into the
opening and push it gently downwards in the direction of the inguinal
canal. On raising the flap of the abdominal wall and looking at its front
aspect, a very striking demonstration of the infundibuliform fascia can thus
be obtained.
There are two forms of Inguinal Hernia,- — viz., oblique and direct.
Oblique inguinal hernia follows the course of the spermatic cord. The
protrusion traverses the entire length of the inguinal canal, entering at the
inlet or internal abdominal ring, and emerging (when the hernia is com-
plete) at the outlet or external abdominal ring. Direct inguinal hernia
only traverses the lower part of the inguinal canal. It pushes before it or
bursts through that part of the posterior wall of the canal which forms the
floor of Hesselbach's triangle, and, having thus gained the interior of the
canal by a short cut, it emerges like the oblique variety at the external
abdominal ring.
The deep epigastric artery bears a different relation to each of these
forms of hernia. This vessel lies close to the inner margin of the internal
abdominal ring, and it forms the outer boundary of Hesselbach's triangle ;
consequently, in oblique inguinal hernia, the protrusion, as it enters the
inguinal canal, lies external to the vessel, whilst, in direct inguinal hernia,
it lies internal to it. So important are these relations, that the terms
external and internal are frequently employed to denote the two forms of
inguinal hernia instead of oblique and direct.
It is also essential that the student should determine the relation which
these forms of hernia hold to the inguinal pouches of peritoneum. In
oblique inguinal hernia the protrusion invariably leaves the abdominal
cavity at the lower and inner part of the external inguinal pouch. It is
here that the internal abdominal ring is situated.
In the case of direct inguinal hernia the protrusion may leave the
abdominal cavity either from the middle or from the internal inguinal pouch,
both of which are in relation to the floor of Hesselbach's triangle.
In almost every case a hernial protrusion in passing to the surface
carries before it a portion of the parietal peritoneum, which constitutes its
immediate covering, and is termed by surgeons the sac of the hernia (Fig.
150, left side). In oblique inguinal hernia the other coverings which the
protrusion acquires are identical with those of the spermatic cord. Entering
the internal abdominal ring, it receives an investment from the infundibuli-
form fascia ; emerging from the lower border of the internal oblique, it
acquires a cremasteric covering ; and, coming out through the external
abdominal ring, it obtains the external spermatic or intercolumnar fascia.
From the surface, then, to the peritoneal sac, the following are the cover-
ings of an oblique inguinal hernia : —
1. Skin and superficial fascia.
2. Intercolumnar or external spermatic fascia.
;. Cremasteric fascia.
EPIDIDYMIS
399
4. Infundibuliform fascia.
5. Extra-peritoneal fatty tissue.
6. Parietal peritoneum, constituting the hernial sac.
In direct inguinal hernia the coverings of the protrusion differ according
to the part of Hesselbach's triangle through which it projects. If the
student examine the floor of this triangular area, he will observe that the
conjoined tendon does not stretch over its entire extent ; that, towards the
outer part of the space, the transversalis fascia alone forms the floor.
When a direct hernia leaves the abdomen from the middle inguinal pouch,
Sac of Tunica
hernia vaginalis
Integument Dartos tunic
Coverings of
cord and testis
Sac of hernia
(in this case the
tunica vaginalis)
Hernia (piece
of intestine)
Testis
Fig. 150. — Diagram to show the different peritoneal
relations in an ordinary inguinal hernia (left side) and a
congenital inguinal hernia (right side).
it is through this outer part of Hesselbach's triangle that it protrudes, and,
in this case, the coverings are almost identical with those of oblique hernia.
1. Skin and superficial fascia.
2. Intercolumnar or external spermatic fascia.
3. Cremasteric fascia (as a general rule).
4. Transversalis fascia.
5. Extra-peritoneal fatty tissue.
6. Parietal peritoneum or sac.
This form of direct hernia is comparatively rare. The more common
form of direct hernia leaves the abdomen from the internal inguinal pouch,
and pushes its way through the inner part of Hesselbach's triangle. It
therefore acquires a covering from the conjoined tendon. The following
are its investments : —
1. Skin and superficial fascia.
2. Intercolumnar or external spermatic fascia.
3. Conjoined tendon.
4. Transversalis fascia.
5. Extra-peritoneal fatty tissue.
6. Parietal peritoneum or hernial sac.
When the conjoined tendon is feeble, or when a direct hernia takes
400
ABDOMEN
place suddenly, the protrusion may burst through it, in which case it does
not obtain a covering from this source.
There are two special varieties of oblique inguinal hernia which it is
necessary to mention — viz., congenital hernia and infantile hernia.
Congenital Hernia. — We have seen that the passage of the testicle from
the abdomen into the scrotum is accompanied by a protrusion of parietal
peritoneum, which lines the inguinal canal and the scrotal sac. This
diverticulum is called the processus vaginalis. Under ordinary circum-
stances the lower part persists as the tunica vaginalis, whilst the upper
part becomes obliterated so as to completely shut off the communication
T.V.
T.V.
Fig.
;i. — Diagram to illustrate the four different varieties
of infantile hernia. (After Lockwood. )
A. Processus vaginalis closed above.
B. Processus vaginalis closed above and
below, but open in intermediate
part.
P.V. Processus vaginalis.
T.V. Tunica vaginalis.
C. Processus vaginalis open throughout its
entire extent.
D. Processus vaginalis closed below, but
open above.
T. Testicle.
S. Hernial sac.
between the general peritoneal cavity and the cavity of the tunica vaginalis.
In certain cases this closure fails to take place, and an open pathway from
the peritoneal cavity into the processus vaginalis is the result (Fig. 145, B. ).
Such a condition is favourable to the occurrence of a hernial protrusion
into the open processus vaginalis, and a hernia of this nature is distinguished
by the term congenital (Fig. 150, right side).
Infantile Hernia. — The conditions favourable to the occurrence of an
infantile hernia are also due to faults in the developmental process by
which the testicle acquires its serous investment. They may be said to
owe their origin to an excess of zeal on the part of the gubernaculum.
The processus vaginalis remains patent, or is only partially closed. The
gubernacular tissue in relation to the parietal peritoneum draws down into
HERNIA 401
the inguinal canal a second test-tube-like diverticulum of the membrane
behind the true processus vaginalis (Fig. 151, S.). This is altogether an
abnormal peritoneal recess which is thus produced, and it gives rise to a
dangerous condition, because at any time an abdominal content may be
forced into it. When this takes place an infantile hernia is the result.
Four varieties are recognised according to the state of the true processus
vaginalis. These are indicated in the diagram (Fig. 151).
Femoral Hernia. — This consists in the protrusion of an abdominal
content from the abdominal cavity into the region of the thigh. In its
descent it passes behind Poupart's ligament along the crural canal or inner-
most compartment of the femoral sheath. It is consequently mainly the
duty of the student who is engaged in the dissection of the lower limb, and
within whose domain the femoral sheath lies, to investigate the anatomical
connections of this variety of hernia (p. 206). Still it is essential that the
dissector of the abdomen should examine, from its abdominal aspect, the
crural ring or aperture of communication between the crural canal and
the abdominal cavity, and give the dissector of the lower limb an oppor-
tunity of doing so likewise.
The crural ring is placed immediately behind Poupart's ligament,
in the interval between the external iliac vein and the base of Gimber-
nat's ligament. If the peritoneum is still in position at this point it
may exhibit a slight digital depression as it passes over the ring. Strip
the peritoneum from the greater part of the iliac fossa. The extra-
peritoneal fatty tissue, which stretches over the crural ring, will be
observed to be denser, stronger, and more fibrous than elsewhere. A
special name is applied to this small portion of the extra-peritoneal
fatty tissue. Seeing that it is applied to the ring in such a manner as
to close the crural canal at its abdominal end, it is called the septum
crttrale. The extra-peritoneal fatty tissue should now be dissected back
with the handle of the knife, to the same extent as the peritoneum. The
fascia iliaca clothing the iliacus and psoas muscles is thus exposed, and
the dissector should note that the external iliac vessels lie upon and not
behind this fascia.
The student is now in a position to study the manner in which the
crural ring is formed. Let him follow the fascia iliaca and the fascia
transversalis towards Poupart's ligament. If the dissection has been
carefully performed, he will observe that to the outer side of the external
iliac vessels these two fascice become directly continuous with each other,
and, further, that along the line of union they are both firmly attached
to Poupart's ligament. It is evident, then, that no hernial protrusion
could leave the abdominal cavity behind Poupart's ligament and external
to the iliac vessels.
In the region of the iliac vessels the arrangement of the fascia will
be found to be different. Here the fascia iliaca is carried downwards
behind the vessels, whilst the fascia transversalis is prolonged downwards
in front of the vessels and behind Poupart's ligament. In the region of
the thigh they together constitute a funnel-shaped sheath*' for the femoral
artery and vein, and for some lymphatics ascending to the abdomen.
This sheath is divided into three compartments by two vertical partitions.
The femoral artery occupies the outermost compartment, and the vein the
middle compartment, whilst the innermost compartment, called the crural
canal, is occupied by the lymphatics, and sometimes by a small lymphatic
gland.
An essential difference between these compartments is this — that
whilst the two outer are completely filled up by the artery and vein, the
crural canal is much wider than is necessary for the passage of its contents.
VOL. I — 26
4o2 ABDOMEN
Gauge the width of the crural ring by introducing the point of the little
finger. It is readily admitted within the opening. Here, then, is a source
of weakness to the abdominal wall, and one which is greater in the female
than in the male, seeing that the distance between the iliac and pubic
spines is proportionally greater, and, in consequence, the crural ring wider.
When the finger is within the ring, mark the structures which surround
it — in front, Poupart's ligament, with the spermatic cord or round
ligament of the uterus ; behind, the ramus of the pubis, giving origin to
the pectineus muscle, which is covered by the pubic portion of the fascia
lata ; internally, the sharp crescentic free border of Gimbernat's ligament ;
and externally, the external iliac vein.
It is still more necessary to note the relations of the blood-vessels
to the crural ring. The external iliac vein has been seen to lie to its
outer side. The deep epigastric artery, as it ascends on the posterior
aspect of the abdominal wall, is close to its upper and outer margin,
and sends its pubic branch inwards in front of it. More important than
any of these is the relation of the obturator artery, when it takes origin
from the deep epigastric. This anomalous vessel may adopt one of
three courses: — (i) It may follow the course of the pubic artery, an
enlarged form of which it in reality is, and pass inwards in front of the
ring, and then descend along its inner margin. In this case, the ring
is surrounded on all sides, except posteriorly, by important vessels.
(2) It may pass downwards and backwards across the crural ring.
(3) It may run downwards between the ring and the external iliac vein
(vide p. 207).
Internal to the crural sheath the passage of a hernial protrusion behind
Poupart's ligament is effectually prevented by Gimbernat's ligament.
Femoral hernia is more common in females, and inguinal hernia in
males ; and for the very evident reason, that in the female the crural
canal is relatively larger, whilst in the male the passage of the spermatic
cord weakens the inguinal region more than the passage of the small
round ligament of the uterus.
Umbilical Hernia. — This form of hernia consists in the protrusion
of an abdominal content through the umbilical ring in the linea alba.
When it occurs in the foetus the hernia passes into the umbilical cord,
and the three vessels are separated by it. More than one case has
occurred in which the bowel has been cut in dividing the cord at the birth
of the child. In the adult the fibrous cords in connection with the
umbilicus are related to the lower border of the ring, and the hernia
escapes through its upper part (Treves).
Penis. — The penis has already, to a certain extent, been
studied in the dissection of the perineum (p. 333). It has
been seen to be composed of the two corpora cavernosa and
the corpus spongiosum. Posteriorly, the corpora cavernosa
separate from each other, become tapered and are attached
to the sides of the pubic arch under the name of the crura
penis ; anteriorly, they together form a blunt rounded
extremity, which is covered by the glans penis. The corpus
spongiosum, when traced backwards into the perineum,
expands into the bulb of the penis, which is attached, in
the mesial plane, to the anterior aspect of the triangular
PENIS
403
ligament ; traced forwards to the extremity of the penis, it is
again found to expand into the glans penis, which fits like a
cap upon the rounded ends of the corpora cavernosa. The
glans penis is somewhat conical in shape, and the projecting
margin of its base is termed the corona glandis. The urethra
opens at the extremity of the glans by a vertical fissure, called
the meatus urinaria s.
The integument of the penis is remarkable for its great
delicacy and elasticity, and the absence of hairs. It has a
brownish tint, and is freely movable over the organ. At the
glans the skin leaves the body of the penis, and, passing for
a variable distance over the glans, is folded back upon itself
so as to form the
prepuce. The deep Glans
layer of the prepuce
reaches the penis
again behind the
corona glandis, and
is then reflected for-
wards over the glans
to become continu-
ous with the mucous
membrane of the
urethra at the meatus
urinarius. A slight
fold will be observed on the under surface of the glans,
extending from the lower angle of the urinary orifice to
the prepuce ; this is the frenum preputii.
Dissection. — Reflect the integument from the surface of the penis by
making a longitudinal incision along the middle line of the dorsum.
The superficial fascia will then be seen to be composed of a quantity of
loose areolar tissue. We never find fat in the meshes of this tissue.
The suspensory ligament and the dorsal vessels and nerves of the penis
should now be dissected.
Corpus
,• cavernosum
»g_ Septum
37 pectiniforme
Urethra surrounded by the
corpus spongiosum
Fig. 152. — Median section through the terminal
part of the Penis.
Suspensory Ligament. — The suspensory ligament is a
strong fibro - elastic band of a triangular shape. , By its
posterior border it is attached to the symphysis pubis.
Towards the penis it separates into two lamellae, which join
the body of the organ, and between which are placed the
dorsal vessels and nerves.
Dorsal Vessels and Nerves. — On the dorsum of the penis, in
the groove which extends along the middle line between the
1— 26 a
4o4 ABDOMEN
two corpora cavernosa, is the dorsal vein : on each side of this
is the dorsal artery, and superficial and external to the artery
is the dorsal nerve. On the dorsum of the penis, therefore,
we find one vein, two arteries, and two nerves.
The dorsal vein of the penis begins by several twigs from
the glans and prepuce. It extends backwards in the middle
line, and disappears between the two layers of the suspensory
ligament. It gains the pelvis by passing under the sub -pubic
ligament, and ends by joining the prostatic plexus of veins.
The dorsal arteries are the terminal twigs of the internal
pudic vessels. Piercing the triangular ligament, they pass
forward between the two layers of the suspensory ligament,
and, continuing their course on the dorsum of the penis,
they terminate in branches from the glans penis.
The dorsal nerves are branches of the internal pudic.
They have a similar course to the arteries,, and end in fine
twigs to the papillae of the glans.
ABDOMINAL CAVITY.
The abdominal cavity may now be opened completely by
carrying an incision from the umbilicus upwards to the ensi-
form cartilage. On throwing the two flaps thus formed
upwards and outwards over the lower margin of the thorax,
a strong fibrous cord, the obliterated umbilical vein, will be
observed extending from the umbilicus to the under surface
of the liver. The obliterated umbilical vein also receives the
name of the round ligament, or ligamentum teres, of the liver.
As it ascends towards that organ, it gradually recedes from
the posterior surface of the anterior abdominal wall, taking
with it a fold of peritoneum, termed the falciform ligament of
the liver.
Shape and Boundaries of the Abdominal Cavity. — The
abdominal cavity is ovoid in shape, its vertical diameter
being the longest. Superiorly, it is roofed by the dome-
shaped diaphragm, which presents a deep concavity towards
the abdomen. Inferiorly, it is floored by the pelvic
diaphragm, which is also concave towards the abdominal
cavity. It is formed by the levatores ani and the coccygei
muscles. Neither the roof nor the floor is complete and
ABDOMINAL CAVITY
405
SUBCOSTAL
PLANE
unbroken. The diaphragm is perforated by certain structures
which pass between the thorax and the abdomen. The con-
tinuity of the pelvic diaphragm is broken by the passage of
certain structures between the pelvic division of the abdominal
cavity and the perineum. The upper part of the abdominal
cavity extends upwards for a considerable distance under the
shelter of the lower ribs and their costal cartilages. The
protection which is thus afforded to the viscera in this portion
of the cavity is most
complete laterally and
behind. In front, as
the costal cartilages
ascend towards the ster-
num, a wide A-shaped
gap is left between those
of opposite sides. The
level to which the costal
arches descend on either
side varies greatly in
different subjects, but
in the great majority of
cases a narrow belt of
abdominal wall, from
one to two inches wide,
is left between the lower
border of the chest wall
and the highest point
of the iliac crest, which
receives no skeletal sup-
port beyond that which
is afforded by the verte-
bral column.
Inferiorly, the ex-
panded iliac bones give support to the abdominal walls
posteriorly and laterally, whilst, in its lowest part, the pubic,
ischial, sacral, and coccygeal bones form very complete bony
boundaries for the cavity.
Whilst the abdominal cavity, therefore, is very fully pro-
tected, posteriorly and laterally, by skeletal parts, the front
wall is almost entirely formed by the muscles and apo-
neuroses which have been dissected in this region.
From this it will be seen that the roof, floor, and the
1— 26 b
INTERTU3ERCULAR
PLANE
LINE
OF
PELVIC BRI
FlG. 153. — Outline of the Abdominal Cavity
as seen in mesial section. The planes
of subdivision
lines.
are indicated bv dotted
406
ABDOMEN
greater part of the abdominal wall are composed of muscular
structures, the contraction of which would diminish the
Fig. 154. — Planes of subdivision of the Abdominal Cavity.
R.H. Right bypochondrium.
R.L. Right lumbar region.
R.I. Right iliac region.
E. Epigastric region.
U. Umbilical region.
H. Hypogastric region.
L. H. Left hypochondrium.
L.L. Left lumbar region.
L.I. Left iliac region.
capacity of the cavity, and subject the contained viscera to
compression.
ABDOMINAL CAVITY 407
Subdivision of the Abdominal Cavity. — In dealing with
so large a cavity, and one which contains such a diversity of
contents, it is absolutely necessary for anatomists to sub-
divide it into regions, in order that the precise position of
each viscus may be accurately defined. In making the first
subdivision, we take advantage of the brim of the true pelvis.
That part of the cavity which is situated above this is termed
the abdomen proper ; whilst that part which lies below it is
called the pelvic cavity. These two portions of the general
abdominal cavity do not lie the one directly over the other.
The long axis of the abdomen proper is very nearly vertical ;
that of the pelvic cavity is very oblique, and directed back-
wards and downwards. Indeed, the pelvic cavity presents the
appearance of a recess leading backwards and downwards from
the lowrer and back part of the abdominal cavity (Fig. 153).
The abdomen proper is still further subdivided by means of
four arbitrary planes of section. Two of these are supposed
to pass through the body in a horizontal direction, and two in
a vertical direction. The former are termed the subcostal and
the intertubercular planes of subdivision, and the position of
each is determined as follows : — A horizontal' line is drawn
around the body at a level corresponding to the most
dependent parts of the tenth costal arches. This gives the
position of the subcostal plane. A second line is drawn
horizontally around the trunk so as to pass through the
highest point on the iliac crest on each side that is seen
from the front. This point is always easily determined, as
a prominent tubercle juts out from the outer lip of the iliac
crest at that spot. It is situated rather more than two inches
behind the anterior superior iliac spine, and it marks the point
where the outline of the body meets the iliac crest. The
line which encircles the body at this level indicates on the
surface the position of the intertubercular plane of subdivision.
The two horizontal planes, thus placed, map out the
abdomen into three districts or zones, which are termed
from above downwards — (1) the costal, (2) the umbilical, and
(3) the hypogastric zone.
The two vertical planes of subdivision are called the right
and left mid-Poupart planes, seeing that they correspond on
the surface to two perpendicular lines reared from the mid-
points of Poupart's ligament.
By these mid-Poupart planes, each of the three zones
1—26 c
4o8 ABDOMEN
determined by the horizontal planes of section is sub-
divided into three.
The costal zone is mapped off into a central epigastric
region and a right and left hypochondriac region ; the umbilical
zone into a central umbilical region and a right and left
lumbar region ; and the hypogastric zone into a central
hypogastric region and a right and left iliac region.
Contents of Abdomen Proper. —Within the abdominal
cavity we find the following structures : —
i. Abdominal part of the o ,,c • ' ,•
.. v . - Small intestine,
alimentary canal. T • . ,■
J \ Large intestine.
2. Glands situated outside^
the walls of the ali- T • .., ., ,, , , , ,
, , I Liver with its trail- bladder or reservoir,
mentary canal and ? ^ &
. -\, . Pancreas,
pouring their secre-
tions into it. J
3. The spleen.
4. The two kidneys, the ureters, and the two suprarenal bodies.
5. Lymphatic glands, lymphatic vessels, the receptaculum chyli, and
the commencement of the thoracic duct.
6. The abdominal aorta, with its various visceral and parietal
branches.
7. The inferior vena cava and its tributaries, and the commence-
ments of the venee azygos major and minor.
S. The vena porta; and its tributaries.
9. The lumbar plexuses of nerves.
10. The abdominal portion of the sympathetic nervous system.
11. The peritoneal membrane which lines the cavity and invests the
viscera.
A mere glance is sufficient to distinguish between the three
primary parts of the alimentary canal within the abdominal
cavity. The stomach is the dilated portion which lies in the
left part of the costal zone. The small intestine succeeds the
stomach, and presents a striking contrast to the large intestine.
The following are the leading points of difference: — -(i) The
calibre of the small intestine is as a rule smaller than that of
the large intestine. Sometimes, however, the large intestine
is very much contracted. It is not unusual to see the part,
termed the descending colon with a diameter not greater than
that of the middle finger. (2) The walls of the small intestine
are smooth and uniform, whereas the walls of the great intestine
are puckered and sacculated. (3) The longitudinal muscular
fibres in the wall of the great intestine are not disposed
uniformly around the tube as in the small intestine, but are
collected into three bands {teenies, coli), which are separated
ABDOMINAL CAVITY 409
from each other by intervals, and are distinctly visible to the
naked eye. These bands are shorter than the tube itself, and
this is the reason of its walls being puckered in the intervals
between them. (4) Attached to the great intestine are
appendices epiploiccc. These are small peritoneal pouches, which
hang from the gut and contain fat.
On opening the abdominal cavity, a very partial view of
the contained viscera is obtained, so long as they are left
undisturbed. ' On the right side of the costal zone the sharp
margin of the liver may be observed projecting slightly below
the ribs, whilst opposite the ninth costal cartilage the fundus
of the gall-bladder is seen peeping out from under cover of
this organ, and projecting slightly beyond its anterior border.
In the same zone to the left of the liver, a portion of the
stomach is visible, whilst extending downwards from the greater
curvature or anterior border of this viscus is a broad apron-
like fold of peritoneal membrane, called the great omentum.
This usually contains a quantity of fat in its meshes, and
is spread out like an apron, so as to hide from view the
viscera which occupy the two lower zones. Sometimes, how-
ever, the great omentum is narrow and short ; or it may
be turned more or less completely upwards or to the side.
In either case some of the coils of the small intestine will
be seen, and also, in all probability, those parts of the great
intestine which occupy the right and left iliac fossae. That
part lying in the right iliac fossa is called the ccecum, whilst
the part situated in the left iliac fossa is the iliac colon. It
may also chance that the bladder is full, in which case its
apex will be observed projecting above the pubes. Lastly,
in pregnant females the gravid uterus will be visible, reachi
a height in correspondence with the period of gestation.
Raise the great omentum and turn it upwards over the
lower margin of the thorax. By this proceeding the coils of
the small intestine are exposed, and a part of the great intestine
which extends across the cavity of the abdomen will be seen
shining through the posterior layer of the great omentum.
This is the transverse colon.
The position and connections of the various viscera should
now be studied.
Liver (hepar). — The liver is the largest gland in the body.
It is a solid pliant organ, the chief bulk of which lies in the
epigastrium. It also occupies the right hypochondrium, and
4io
ABDOMEN
extends for a variable distance into the left hypochondrium.
Further, the lower right margin crosses the subcostal plane,
and enters for a short distance into the upper part of the
right lumbar region.
The liver has the shape of a right-angled triangular prism
Liver-
Stomach
Root of
tery
meso-colon
Cajcum^tft
Pelvic colo
Bladder
Fig. 155.— The Abdominal Viscera as seen from the tront after removal of
jejunum and ileum with their mesentery. The dark lines indicate the
subdivision of the abdominal cavity. (Birmingham. )
(Symington), but its substance is so pliant that its natural
configuration can only be preserved when special measures are
adopted for this purpose. It presents five surfaces, viz., an
inferior, a superior, an anterior, a posterior, and a right lateral
surface. The inferior surface is oblique, looks downwards
and to the left, and is in relation to other viscera within the
ABDOMINAL CAVITY 411
abdomen ; it may therefore be specially distinguished by the
name of visceral surface. The other four surfaces are applied
to the diaphragm and abdominal parietes, and they pass
insensibly into each other by means of rounded borders.
They may thus be grouped together under the one term of
parietal. A sharp attenuated margin separates the inferior
or visceral surface from the right lateral, from the anterior, and,
at the left extremity of the organ, from the superior surface.
This margin constitutes a prominent feature of the liver.
At the present moment, with the organ in situ, the con-
nections of the liver are such that the posterior surface cannot
be studied at all, and the inferior or visceral surface only
partially. The other three surfaces and the sharp margin
can be fully examined. The right lateral surface forms an
area of some extent, which passes vertically downwards in
relation to the lateral portions of the seventh, eighth, ninth,
tenth, and eleventh costal arches. It is separated from
these, however, by the diaphragm and the thin basal margin
of the right lung. It is convex from before backwards, and
is adapted to the curvature of the ribs, under the shelter of
which it lies. This surface passes insensibly by means of
rounded borders into the superior, anterior, and posterior
surfaces. Inferiorly, however, the sharp margin of the liver
marks it off in the most distinct manner from the inferior
or visceral surface. This portion of the sharp margin con-
stitutes the most dependent part of the liver, and extends for a
variable distance below the subcostal plane into the right
lumbar region.
The superior surface is adapted accurately to the under
surface of the diaphragm. Its right portion rises in the
form of a high convexity, which occupies the right cupola
of the diaphragm. Immediately to the left of this is a
depressed slightly concave area (impressio cardiaca), which
corresponds to the heart and pericardium on the upper surface
of the diaphragm ; whilst, still farther to the left, the superior
surface of the liver again shows a convexity, but not so
pronounced as that on the right side, which fits into the left
cupola of the diaphragm. Full rounded borders separate
this surface from the right lateral, from the anterior^ and from
the posterior surfaces of the liver. At the left extremity of
the organ, the superior surface is separated frorrLAhe inferior
or visceral surface by the left portion of the shar Jfljpgin.
4i2 ABDOMEN
The anterior surface of the liver, which looks directly
forwards, presents a triangular outline. The base of the
triangle is formed by the rounded border which separates this
surface from the right lateral surface ; the upper limit is
formed by the rounded border which intervenes between the
superior and anterior surfaces ; and the lower limit by the
anterior sharp margin of the liver. The apex of this triangular
area points to the left, and corresponds with the left extremity
of the organ. The greater part of the anterior surface lies
Coronary ligament
:-2j|r ^Ligamentum teres
ja^faf"^ ——-.Gall-bladder
Fig. 156. — Anterior Surface of the Liver.
against the diaphragm, and under cover of the lower ribs
and costal cartilages of the right side. Its left part lies under
shelter of the costal arches of the left side ; whilst in the
A-shaped interval between the costal cartilages of opposite
sides it lies behind the ensiform cartilage, and, for a variable
distance below this, in direct relation to the posterior surface
of the anterior abdominal wall.
Attached to the anterior and superior surfaces of the liver
will be seen the broad peritoneal falciform ligament (liga-
mentum falciforme hepatis), which maps out the organ into a
right and a left lobe. The smooth glossy appearance of the
ABDOMINAL CAVITY 4T3
three surfaces we have examined is due to the peritoneal
investment of the organ. If the hand be passed backwards
over the upper surface of the liver, it is prevented from
reaching the posterior surface by the reflection of the peri-
toneum from the upper surface of the organ on to the under
surface of the diaphragm. This reflection forms the upper
layer of the coro?iary ligament.
The posterior and inferior surfaces of the liver can only be
satisfactorily studied after the removal of the organ. Still,
there are several important points in connection with the
inferior or visceral surface which can be best ascertained
under the present conditions. This surface is very oblique ;
it slopes from the right inferior sharp margin upwards to the
left extremity of the organ, so that it looks very nearly as
much to the left as downwards. It follows from this that the
vertical depth of the liver diminishes rapidly as it extends to
the left. In relation to this sloping inferior surface there are
a number of viscera, all of which leave their imprint upon
the liver in the shape of fossae of greater or less depth. Thus
the left lobe is moulded over the stomach, whilst in contact
with the inferior surface of the right lobe are: — (1) the gall-
bladder, which is bound down to it by peritoneum; (2)
the pyloric end of the stomach and the duodenum or com-
mencement of the small intestine; (3) the hepatic flexure of
the colon ; and (4) the right kidney. The precise relations
of these organs to the liver will be studied more fully at a
later stage.
The sharp margin of the liver forms a continuous attenuated
border, although it is convenient to speak of it as consisting
of a right inferior part intervening between the right lateral
surface and the inferior surface ; an anterior part, which
separates the anterior surface from the inferior surface ; and
a left portion, which turns round the left lobe and forms its
left fine edge or extremity. The anterior part of the sharp
margin presents a slight' deficiency where it is adapted to the
fundus of the gall-bladder, and a notch {incisure/, umbilical is) of
varying depth where the falciform ligament meets 'the liga-
mentum teres or obliterated umbilical vein.
To map out the liver on the anterior surface of the body take three
points : (a) half an inch below the right nipple ; (d) one inch below the
left nipple ; (r) on the right side one inch below the extremity of the
tenth rib. Join b and c ; this will give fairly accurately the lower limit of
4t4 ABDOMEN
the organ. Next draw a curved line, convex to the right, between a and
c ; this marks out the right limit. A line extending from a to b will
indicate the upper limit. But this upper line must be drawn with some
care. At each extremity it must be curved upwards, whilst the intermediate
portion must cross the sternum at the level of the junction of the sixth
costal cartilages and be somewhat depressed in correspondence with the
depressed area on the upper surface of the liver which lies under the
pericardium (Birmingham).
Even in health the position and shape of the liver is subject to con-
siderable variation. From its intimate connection with the diaphragm
it is easy to understand how it must rise and fall with every respiratory
act. Further, the full or empty condition of the neighbouring hollow
viscera affects not only its form, but also its position. Displacement
of the liver from artificial causes, such as tight-lacing in females, is by
no means uncommon. A gravid uterus, also, as it gradually ascends in
the abdominal cavity, exercises a marked influence upon the shape of the
liver.
Gall-Bladder (vesica fellea). ■ — The gall-bladder should be
examined in connection with the liver. This small pyriform
sac lies in the epigastric region close to the right mid-Poupart
plane. Its fundus, covered by peritoneum, peeps out from
under cover of the anterior margin of the liver, but in the
rest of its extent it is bound down by a partial peritoneal
investment to the under surface of the right lobe of that organ.
Spleen (lien). — The spleen is a solid organ, which lies deeply
in the left part of the costal zone, and is altogether out of
sight in the undisturbed condition of the viscera. By drawing
the stomach to the right, and thrusting the hand into the
left hypochondrium, it can readily be discovered and pulled
forwards for inspection. It lies very obliquely in the abdominal
cavity, its upper end being much nearer the mesial plane
than its lower end. Its long axis is directed from above
downwards and outwards, and also to some extent forwards.
For the most part it lies in the left hypochondrium, but its
upper end extends inwards beyond the left mid-Poupart
plane, so that fully a third of the organ is situated in the
epigastric region.
The spleen when properly hardened in situ has the shape
of an irregular tetrahedron. The upper extremity (extremitas
superior) is curved, to some extent forwards on itself, and
approaches close to the left suprarenal capsule.
Of the four surfaces the most extensive is the diaphragmatic
(superficies diaphragmatica), which is convex and looks back-
wards and outwards. It rests upon the back part of the
diaphragm, to the curvature of which it is adapted. By
the diaphragm it is separated from the ninth, tenth, and
ABDOMINAL CAVITY
4i5
eleventh ribs. It is necessary also to remember that the
pleura descends between this portion of the chest wall and
the diaphragm and comes to lie superficially to the greater
part of the diaphragmatic surface of the spleen. The thin
basal margin of the lung which occupies the upper part of
the pleural recess likewise intervenes between the upper part
of the spleen and the surface of the body.
The remaining three surfaces are turned towards the cavity
of the abdomen, and are closely applied to the viscera which
support the organ in its place. These three surfaces, which
Anterior
angle
Intermediate angle
Fig. 157. — The Spleen (visceral as;
may be grouped together under the one term " visceral," are
separated from each other by three ridges which radiate from
a blunt and often inconspicuous prominence which may be
termed the intermediate angle, and represents the apex of the
tetrahedron. One of these ridges, a salient and prominent
border (margo intermedius), ascends to the upper end of the
spleen and separates an extensive anterior gastric area from
a narrower posterior renal area : a second short ridge or
border passes backwards to the posterior angle and intervenes
between the renal and the colic surfaces ; whilst the third
ridge, less distinctly marked, proceeds forwards to the
anterior angle and separates the gastric and the colic surfaces
4i 6 ABDOMEN
from each other. The term colic surface is applied to a
triangular area which is bounded by the two last-named
ridges, together with the lower border of the organ.
The gastric surface (superficies gastrica) is the most extensive
of the three visceral districts. It is deeply concave and
moulded upon the fundus of the stomach. Within its area
and about an inch or so* in front of the margo intermedius
is situated a longitudinal slit, frequently broken up into two
or more pieces, and termed the hilum. This gives passage
to the vessels and nerves which enter and leave the organ.
Behind the hilum and immediately in front of the inter-
mediate angle there is a pancreatic depression of variable extent
and depth into which the tail of the pancreas is received.
The renal surface (superficies renalis) is flat and even, and
varies somewhat in its extent. It is applied to the anterior
surface of the upper part of the kidney close to its outer
border.
The peritoneal relations of the spleen are such that the renal surface
cannot be studied unless the posterior border of the organ is pulled
forwards, so that we can see behind it.
The colic surface (superficies basalis) is smaller than the
other two visceral areas. It is triangular in form, and looks
downwards and inwards. It is in contact with the splenic
flexure of the colon and the costo-colic ligament.
Of the several borders which separate the different surfaces
of the spleen from each other, the anterior, the inferior,
and the posterior are the most prominent and conspicuous.
The a?iterior border (margo crenatus) is notched or crenated,
and intervenes between the diaphragmatic surface and the
gastric surface. The inferior border separates the diaphrag-
matic surface from the colic surface ; whilst the. posterior boj-der
(margo obtusus) intervenes between the renal and diaphrag-
matic surfaces. The other margins which separate the visceral
areas from each other radiate out from the intermediate angle,
and have been already noticed.
A characteristic feature of the typically formed spleen is
the great prominence of the anterior angle. It forms the
most anteriorly placed part of the spleen.
The form of the spleen varies very greatly with the varying degrees of
distension of the hollow viscera which are related to its visceral aspect.
There is good reason to believe that the tetrahedral form which is described
ABDOMINAL CAVITY
4i7
above is associated with an empty or slightly distended stomach and a
well-distended intestine. When, however, the stomach is distended and
the gut more or less empty, the basal
surface partially or even entirely dis-
appears, and then the spleen assumes a
form similar to that of the segment of an
orange (Shepherd).
Hyoid bone
Thyroid car-
tilage
Cricoid cartilage
Trachea
(Esophagus
Aortic arcli
Descending aorta
Oesophagus
Peritoneal Connections of the
Spleen. — Passing from the fundus
of the stomach to the gastric sur-
face of the spleen along the line
of the hilum is a fold of peri-
toneum known as the gastro-splenic
omentum ; whilst tying the visceral
aspect of spleen down to the
surface of the kidney is another
short fold called the lieno-renal
ligament. It is between the two
layers of the lieno-renal ligament
that the splenic vessels reach the
hilum of the organ.
Stomach (ventriculus). — The
stomach is the most dilated part
of the alimentary
canal, and it con-
stitutes the receptacle
for the food after it
has been masticated
and swallowed. The gullet or
oesophagus opens into the
stomach above and to the left,
whilst below and to the right
the stomach becomes continuous
with the duodenum or first part
of the small intestine. The form
and the position of the organ
within the abdomen are greatly
influenced not only by the
amount of food it contains but
also by the empty or distended
condition of the other hollow
viscera in its vicinity. It is convenient to describe it
as it appears when moderately distended. It then assumes
vol. 1 — 27
Thoracic duct
1 2th dorsal vertebra
Abdominal aorta
Fig. 158. — The (Esophagus,
Stomach, and Duodenum.
4i8
ABDOMEN
a pyriform shape and is strongly curved upon itself. It
is customary to recognise in connection with the stomach :
(i) a blunt left extremity or fundus; (2) a narrow right
extremity or pylorus ; (3) two orifices, a cardiac and a
pyloric ; (4) two surfaces, a superior and an inferior ; and
(5) two borders or curvatures, a greater and a lesser.
The fundus, or left cardiac end, is full and rounded and
forms a marked bulging directed upwards and backwards. It
occupies the back part of the left cupola of the diaphragm,
from which it is in part separated by the spleen and the
(Esophagus
Fundus
Duodeno-pyloric
constriction
Duodenum
Pyloric \^fe«.
vestibule IK
^1
Attachment of
great omentum to
greater curvature
Fig. 159. — Stomach of a Child, two years of age, hardened in situ
by formalin injection.
liver. To the right of the fundus and about two inches
below its summit is the oesophageal or ca?-diac orifice. This
is placed on the upper part or commencement of the lesser
curvature, but in certain conditions of the stomach it appears
to be partly on the upper surface. At this point the
organ is joined by the gullet. The pylorus or narrow right
extremity of the stomach, which as a rule is directed back-
wards, becomes continuous with the duodenum or com-
mencement of the small intestine, and the junction is marked
on the surface by a slight but distinct constriction, termed
the duodeno-pyloric constriction.
ABDOMINAL CAVITY
419
The two surfaces of the stomach, as a general rule, look
for the most part upwards and downwards. The upper surface
is fuller and more convex than the lower surface. To some
extent it is directed forwards as well as upwards, and it is
largely covered by the left lobe of the liver. Below and to
the left of the sharp margin of the liver, however, a consider-
able portion of this surface of the stomach is in apposition
with the diaphragm, and also with the posterior aspect of
the anterior abdominal wall.
The inferior surface of the stomach is flatter than the
Left crus of
diaphragm
Suprarenal
capsule
Fig. 160. — The Stomach has been removed from its bed so as to display
the recess in which it lies.
superior surface, and is supported by a slightly curved and
sloping shelf, which projects forwards from the posterior wall
of the abdomen. This has been appropriately called by
Birmingham the stomach-bed, and it is formed by the following
structures, all of which are related to the lower surface of
the organ : (1) the gastric surface of the spleen ; (2) the left
suprarenal capsule and a varying amount of the upper part of
the left kidney; (3) the upper surface of the pancreas; (4)
the transverse meso-colon ; and (5) the transverse colon.
The lesser sac of the peritoneum alone separates the stomach
from the spleen, suprarenal capsule, kidney, pancreas, and
i—27"
420
ABDOMEN
colon, whilst the transverse meso-colon intervenes between it
and the coils of the small intestine.
The right or posterior border of the stomach is termed its
lesser curvature. It extends from the cardiac orifice to the
pylorus, and curves round the base of the tuber omentale, an
eminence on the under surface of the liver, and also to a
smaller extent round the corresponding prominence of the
pancreas. It is therefore concave, and from it proceeds a
fold of peritoneum, called the gastro-hepatic omentum, which
Duodenum
(ist part)
Duodeno-pyloric^
constriction
Pyloric canal
(Esophagus
Pyloric
vestibule
Fig. i 6 i.— Outline of the upper aspect of the Stomach of a Child which has
been hardened in situ by formalin injection. It is the same stomach
as is figured on p. 418. The arrow directed towards the lesser curva-
ture points to the incisura angularis ; the arrow directed towards the
greater curvature points to the sulcus intermedins.
connects the stomach to the liver and the diaphragm. The left
or anterior border of the stomach, called the greater curvature,
on account of its great length, is convex and is directed to
the left and forwards. From this border an extensive
peritoneal fold, termed the great omentum, hangs down-
wards.
The stomach is not only curved from one end to the other but it is also
bent upon itself more or less acutely so that a notch or angular depression,
the incisura angularis, is produced in the lesser curvature (Fig. 161).
Advantage is taken of this notch to divide the organ for descriptive
purposes into a large cardiac part which lies to the left and a much smaller
pyloric part which lies to the right of the incisura.
ABDOMINAL CAVITY 421
The cardiac part of the stomach is generally considered to consist of a
fundus and a body. An imaginary line drawn around the organ from the
cardiac orifice to a point on the greater curvature directly opposite is taken
as separating these portions of the stomach from each other.
The short pyloric part of the stomach is composed of a pyloric canal and
a pyloric vestibule. The pyloric canal is a short, narrow, usually cylindrical
part, about one inch or one inch and a quarter long, which immediately
adjoins the duodeno-pyloric constriction. It thus constitutes the right
extremity of the stomach, and its thick muscular walls and its cylindrical
form give it a special character of its own. The pyloric canal is as a rule
directed backwards, and it is marked off from the pyloric vestibule by a
slight notch in the greater curvature termed the sulcus intermedins. The
pyloric vestibule lies to the left of the pyloric canal and the sulcus inter-
medius. It is wider than the pyloric canal and its walls are not so thick.
But there is also a physiological subdivision of the stomach. During
the process of active digestion the right half of the body of the stomach and
the whole of the pyloric portion, by the firm contraction of their walls,
assume a tubular form. In this tube a thorough mixture and trituration
of the food is effected by means of constriction waves which pass over it in
regular procession from left to right. The fundus and left half of the body
of the stomach maintain a saccular form, and constitute a passive reservoir
from which food is squeezed into the more active tubular part to take the
place of the material which intermittently escapes from the stomach into
the small intestine.
When the stomach is empty it is questionable if it ever assumes during
life the flaccid, relaxed, and flattened form which is so frequently seen in the
dissecting room, in subjects which have not been specially hardened. In
life, the healthy stomach, by contraction of its muscular coat, adapts itself
to its contents whether these be liquid, gaseous, or solid, and when emptv
and contracted its walls become thick and firm.
Position of the Stomach. — When empty and contracted the
stomach lies more or less horizontally within the abdominal
cavity. It is placed within the left hypochondrium and the
left portion of the epigastrium. The organ is bent on itself
like a sickle and the fundus sinks downwards so that it comes
to look directly backwards ; the surfaces are directed upwards
and downwards and the curvatures forwards and backwards
— the greater curvature being at a slightly higher level than
the lesser curvature : lastly, there is a gradual but decided down-
ward slope of the upper surface from the fundus to the pylorus.
The pyloric extremity of the empty stomach either occupies
the mesial plane or lies at a point about half an inch or so to
the right of this plane. Addison's method of indicating the
position of the pylorus (in this condition of the organ) on
the surface of the abdomen is probably the best. Draw a
line from the top of the manubrium sterni to the symphysis
pubis ; bisect by a horizontal line drawn across the front of
the abdomen. A point on this latter line, half an inch to the
right of the mesial plane, lies over the pylorus.
42
ABDOMEN
The conditions which give rise to the position and form of the empty
stomach as described above are sufficiently obvious when the nature of the
chamber within the abdomen which is occupied by the organ is considered.
The roof of this chamber formed by the liver and diaphragm is more
resistant, more unyielding, than the floor, which is chiefly formed by the
transverse meso-colon buoyed up by the movable coils of small intestine.
As the stomach becomes empty and contracted, the intestines, acted on by
the abdominal wall, rise up and press it against the sloping visceral
surface of the liver, and the slope or gradual descent to the right which is
so characteristic a feature of the upper surface of the empty stomach is the
result.
Pyloric canal of stomach
Inferior vena cava
Duodeno-pyloric constriction
Suprarenal capsule \
Duodenum (ist part)
Kidney (right) \
\
Oesophagus
Stomach
/
Spleen (colic
surface)
Duodenum (2nd part)
Head of pancreas
Superior mesenteric vessels
Tail of pancreas
Kidney (left)
Suprarenal capsule
Ureter
Duodenum (3rd part)
Fig. 162. — Horizontal position of the Stomach in a Child two years
old ; viscera hardened bv formalin injection.
When the stomach becomes ///// it may either retain the
horizontal position which is characteristic of the organ when
it is empty or it may assume a more or less oblique position.
In both cases it occupies more space within the abdomen by
the displacement of neighbouring viscera and the pylorus
moves to the right, but not as a rule more than an inch and
a half, or at most two inches, from the mesial plane. The
pylorus does not alter in a vertical direction ; it main-
tains the same level within the abdomen. The position of
the cardiac opening is only slightly affected by the emptying
ABDOMINAL CAVITY 423
or the distension of the stomach. It is placed opposite the
body of the tenth dorsal vertebra, and on the surface of the
body its situation may be indicated by placing the finger on
the seventh costal cartilage of the left side about one inch
from its junction with the sternum.
As the stomach fills it becomes more rounded in general
outline, and should it assume the oblique position when full
the fundus is directed upwards whilst the surfaces look
forwards and backwards ; further, the part of the greater
curvature opposite the incisura angularis takes a mesial
position and occupies a lower level than any other part of
the stomach. It follows from this that the pyloric part
of the organ courses upwards and to the right to reach its
termination.
In considering the various conditions which determine the position and
form of the full stomach it is necessary to take into account the state of the
movable, and as a rule yielding, floor of the stomach chamber. It is
possible that the easiest and most natural way for the stomach to expand,
under ordinary circumstances, is in a downward direction by intestinal
displacement, and when this occurs the oblique portion of the organ is the
result. But when the intestines are distended the stomach cannot acquire
the necessary space in this manner, and the liver, which forms so large a
part of the roof of the stomach chamber, has to give way before it. The
obvious result of such a change in the position and form of the pliant liver
is that the full stomach retains the horizontal position.
(Esophagus. — The portion of the gullet which is placed
within the abdomen is very short, and occupies a groove on
the back aspect of the left lobe of the liver. The oesophagus
joins the stomach, when the parts are in their natural position,
so as to form a very decided angle with its upper surface.
By pulling the left lobe of the liver aside the junction between
the gullet and the stomach will be seen.
Relations between Thoracic and Abdominal Organs. — At
this stage it is useful to consider the relations which exist
between the abdominal and thoracic organs which lie upon
the different aspects of the diaphragm. We have seen that
the right lobe of the liver occupies the right vault of the
diaphragm, whilst the left lobe of the liver, the fundus of the
stomach, and the spleen occupy the left vault. The base of
the right lung is in relation to the right lobe of the liver.
The pericardium, in by far the greater part of its extent, lies
above the left lobe of the liver, which therefore intervene-
between it and the stomach ; only a limited portion of the
apex of the heart extends over the region of the stomach.
424 ABDOMEN
The base of the left lung lies over the left lobe of the liver,
the fundus of the stomach, and the spleen.
Small Intestine (intestinum tenue). — The small intestine
is that part of the alimentary canal which succeeds the stomach.
It begins in the epigastric region at the pylorus, and ends in
the lower part of the right lumbar region by joining the great
intestine. Its average length is somewhere about twenty-
three feet, and as it is traced towards its termination it will be
seen to diminish slightly in calibre. It is divided into three
portions, viz. : —
i. The duodenum.
2. The jejunum.
3. The ileum.
The duodenum is the name which is given to the first
part of the small intestine. It is about ten inches long, and
extends from the pylorus to the left side of the body of the
second lumbar vertebra. As it lies deeply in the greater part
of its extent, and as dissection is necessary to bring out its
relations, it is better to defer its description for the present.
The jejunum and ileum constitute the coils of the small
intestine, and are more or less completely covered by the
great omentum. The jejunum begins where the duodenum
ends, viz., on the left side of the body of the second lumbar
vertebra ; and the ileum ends in the lower part of the right
lumbar region by joining the caecum or the commencement of
the great intestine. The subdivision of the small intestine is
of the most arbitrary kind. After mapping off the duodenum
it is customary for anatomists to look upon the upper two-
fifths of the remainder as being jejunum, and the lower three-
fifths as being ileum. There is no hard-and-fast line of
demarcation between the lower two divisions — the one passes
insensibly into the other ; and as the chief distinction is to be
found by an examination of the interior of the tube, the student
will not in the meantime see much difference between them.
To expose the commencement of the jejunum, the great
omentum with the enclosed transverse colon should be thrown
upwards over the lower margin of the thoracic wall. The
coils of the small intestine should then be drawn over to the
right. The junction between the duodenum and the jejunum
will now be seen on the left side of the vertebral column, at
the level of the second lumbar vertebra. The termination of
the duodenum is fixed, and the commencement of the jejunum
ABDOMINAL CAVITY 425
bends suddenly forwards and downwards upon it, forming the
duodenojejunal flexure. To bring the termination of the ileum
into view, the coils of the intestine should be turned over to
the left. The terminal part of the ileum, which almost
invariably lies in the pelvis, has no great latitude of move-
ment. It passes upwards across the iliac vessels and upon
the psoas muscle, to join the caecum at the level of the inter-
tubercular plane, and close to the right Poupart plane.
The coils formed by the jejunum and ileum are suspended
from the posterior wall of the abdomen by a wide fold of
peritoneum, called the mesentery. They are thus freely
movable within the cavity. Owing to the manner in which
the mesentery is attached to the posterior wall of the abdomen
(Fig. 155, p. 410), they tend to lie more in the left than in
the right portion of the cavity, and they occupy the umbilical,
hypogastric, lumbar, and iliac regions, filling up the greater
part of the abdominal cavity below the transverse colon and
its mesentery. A variable number of coils extend downwards
into the pelvis, and not uncommonly some coils of the
jejunum may be found in the left hypochondrium.
Meckel's Diverticulum. — In about 2 per cent of subjects dissected, a
blind, hollow protrusion termed Meckel's diverticulum juts out at a right
angle from the wall of the ileum at a point rather less than three feet
from the junction of the small intestine with the caecum. It represents
a persistent portion of the vitelline duct of the embryo, and under certain
circumstances it may lead to conditions which require surgical interference.
Large Intestine (intestinum crassum). — The large intestine,
although, in its distended condition, possessing a much wider
calibre than the small intestine, is not nearly so long. It
extends from the right iliac fossa to the anus, and it rarely
measures more than five or six feet in length. Like the
small intestine, it is widest at its commencement, and gradually
diminishes in diameter as it advances towards its termination.
It is subdivided more or less arbitrarily into the following
parts : —
The caecum and vermiform appendix.
-Ascending colon.
Hepatic flexure.
Transverse colon.
The colon.- Splenic flexure.
Descending colon.
Iliac colon.
^Pelvic colon.
The rectum.
The anal canal.
426 ABDOMEN
Caecum (caput caecum coli). — The caecum is the blind com-
mencement of the great intestine. It lies in the right iliac fossa,
on the ilio-psoas muscle, and immediately above the outer half
of Poupart's ligament. Except in a few exceptional cases
(6 to 7 per cent) it is completely enveloped by the peritoneum,
and is thus allowed some latitude of movement. When dis-
tended it is in contact with the anterior abdominal wall, but
when it is empty and collapsed it is usual to find some coils
of the small intestine intervening. The terminal part of the
ileum, which passes upwards on the inner side of the caecum,
opens into it upon its inner and hinder aspect about two and
a half inches above its blind end, and marks the point where
it becomes continuous with the ascending colon.
On the surface of the anterior abdominal wall the position of the
ileo-csecal orifice may be determined by the fact that it lies subjacent to
the point at which the Poupart and the intertubercular lines intersect.
Vermiform Appendix (processus vermiformis). — In con-
nection with the caecum the dissector will find the vermiform
appendix. This is a narrow caecal tube, which has a diameter
slightly greater than that of a goose quill, and a length which
varies from three to five or six inches, or even more. It
opens into the caecum upon its inner and back aspect below
the termination of the ileum, and is provided with a small
peritoneal fold, which constitutes its mesentery. It cannot
be said that the appendix has any fixed position. It may
occupy any situation consistent with its length and the
latitude of movement allowed by its mesentery. Probably
the most usual position which it assumes is one behind the
caecum. In many cases, however, it lies behind the terminal
part of the ileum and its mesentery, whilst in others it curves
over the psoas and dips into the pelvis. The taeniae, coli or
three longitudinal muscular bands on the wall of the caecum
meet at the base of the appendix and give it a continuous
and uniform coating of fibres. The anterior taenia coli on
the caecum, if followed downwards, affords a sure guide to the
appendix.
The orifice of the appendix may be determined on the surface by
placing the finger upon the right Poupart line one inch below the inter-
tubercular plane.
Ascending Colon (colon ascendens). — The ascending colon,
about 8 inches long, extends upwards through the right
ABDOMINAL CAVITY 427
lumbar region, until it reaches the under surface of the right
lobe of the liver. It is continuous below with the caecum,
whilst above it becomes the hepatic flexure. It is usually
clothed anteriorly and laterally by peritoneum, whilst pos-
teriorly it is bare ; and this bare surface rests upon the fascia
covering the upper part of the iliacus muscle, the quadratus
lumborum muscle, and upon the lower part of the anterior
surface of the right kidney, with each of which it is connected
by a little loose areolar tissue. In certain cases the peri-
toneum may surround the tube, and form behind it a short
meso-colon.
The hepatic flexure (flexura coli dextra) is the bend which
connects the ascending colon with the transverse colon.
When the colon reaches the inferior surface of the right lobe
of the liver, it bends forwards and then turns suddenly to
the left, and this curvature constitutes the flexure. The
summit of the curve lies in the right hypochondrium. It
occupies a marked depression on the under surface of the
liver to the right of the gall-bladder, and is placed in front of
the lower part of the kidney. Like the ascending colon, it
is only partially covered by peritoneum. Its posterior surface
is more or less bare, and in direct contact with the kidney.
Transverse Colon (colon transversum). — The transverse
colon is continuous on the one hand with the hepatic flexure,
and on the other with the splenic flexure. It is the longest
part of the great intestine (eighteen to twenty inches), and it
stretches across the entire width of the abdominal cavity. At
first it descends into the umbilical region, and then ascends
into the left hypochondrium. It takes an arched course, the
summit of the arch bein^ nearer the anterior wall of the
abdomen, and at the same time at a lower level in the body.
than its extremities. The transverse colon possesses greater
freedom of movement than any other part of the great
intestine. It is attached to the posterior abdominal wall by
a wide peritoneal fold, called the transverse meso-colo?i. Its
right extremity lies in front of the duodenum, whilst its left
extremity is in close relation to the lower surface of the
pancreas and the base of the spleen.
The splenic flexure (flexura coli sinistra) is the term applied
to the bend which the colon takes in the left hypochondrium,
before proceeding downwards as the descending colon. It
is placed at a higher level and gains a deeper plane in the
428
ABDOMEN
abdominal cavity than the hepatic flexure, and it receives its
name from the fact that it lies in more or less intimate
relation with the colic surface of the spleen. A fold of
peritoneum, with a free, crescentic border, binds it to the
diaphragm opposite the tenth or eleventh rib. This fold is
called the phrenico-colic ligament or the sustentaculum lienis.
When the stomach is empty and the colon distended with gas, the
transverse colon, where it adjoins the splenic flexure, may rise so as to
occupy a position against the vault of the diaphragm, beside or in front
of the fundus of the stomach. In such a case it intervenes between the
stomach and the thoracic wall, and would yield a tympanitic note upon
percussion.
Ureter
D.C. Descending colon.
Q.L. Quadratus lumborum.
P. Psoas.
E.S. Erector spinae.
I,. IV. Fourth lumbar vertebra
Fig. 163. — From a tracing of a transverse section through the
abdomen, at the level of the fourth lumbar vertebra.
p.\ and/. 2 indicate the points at which the peritoneum is reflected
from the descending colon on to the posterior wall of the abdomen.
Descending Colon (colon descendens). — The descending
colon, 5 or 6 inches long, takes a vertical course downwards
through 'the left lumbar region, and, on gaining the crest of
the ilium, becomes continuous with the iliac colon. Its calibre
is less than that of the ascending colon, and very frequently
it is found in a firmly contracted condition. As it pro-
ceeds downwards it first curves round the outer margin of
the left kidney and then descends more or less vertically in
the angle between the psoas and the quadratus lumborum
muscles.
Its anterior surface and its sides are covered by peritoneum,
ABDOMINAL CAVITY 429
but in the great majority of cases its posterior surface is bare,
and connected to the lower part of the diaphragm and the
cjuadratus lumborum, on both of which it rests, by loose
areolar tissue.
Iliac Colon (colon iliacum). — The iliac colon is a short
portion of the great intestine, not more than five or six inches
in length, which takes a slightly curved course downwards
and inwards in the left iliac fossa. Above, it begins at the
iliac crest, where it is continuous with the descending colon ;
below, it turns over the inner margin of the psoas muscle,
enters the pelvis and becomes the pelvic colon. As a rule
the peritoneum is related to it in very much the same manner
as in the case of the descending colon ; it clothes it anteriorly
and laterally, but leaves its posterior surface bare. This surface
is connected to the ilio-psoas muscle, on which it lies, by
areolar tissue. In a certain number of cases (10 per cent
according to Jonnesco) it receives a complete investment of
peritoneum and is provided with a mesentery.
Pelvic Colon (colon pelvicum). — Next to the transverse
colon this is, as a rule, the longest section of the great intestine,
and indeed it not infrequently exceeds the transverse colon in
length ; on the other hand, it should be remembered that it is
sometimes greatly reduced in length. It forms a long loop,
freely movable owing to its being provided with an extensive
mesentery, termed the pelvic meso-co/ou, but its two extremities
are fixed and are placed in close proximity to each other.
The upper end, which is continuous with the iliac colon, is
placed on the inner margin of the left psoas ; the opposite
extremity is fixed by the shortening and disappearance of the
mesentery to the front of the third piece of the sacrum, and
here it becomes continuous with the rectum.
The pelvic colon is thus completely invested with peri-
toneum, and as a rule it is stowed within the cavity of the
pelvis in intimate relation to the rectum and bladder and
also to the uterus in the female. It is subject to much
variation, however, both in length and in position, and in
certain cases, either through its own distension or through
the distension of the bladder and rectum, or through both
causes acting together, it comes to occupy a place in the
abdominal cavity.
The rectum and the anal canal will be described with the
pelvic viscera.
43o ABDOMEN
Adaptation of the Abdominal Walls to the Viscera,
and of the Viscera to each other. — The abdomen is an air-
tight cavity, and the atmospheric pressure acts upon its
mobile walls so as to keep them constantly in accurate
apposition with the viscera, and also the viscera in accurate
contact with each other. During life, and in the undissected
subject, no space of any kind is left vacant. The external
configuration of the solid organs within the abdomen is
determined by this close adaptation of walls to contents, and
of viscus to viscus. The liver is the best example of this —
every structure with which it is in contact by its visceral
surface leaves its mark upon it in the form of a depression,
whilst its parietal surface presents an exact mould of the under
surface of the diaphragm and other parts of the abdominal
parietes with which it is in apposition. During life the hollow
viscera are constantly undergoing changes of form, and they
react upon the pliable solid organs and model them in such
a manner that they also undergo striking alterations in form.
Peritoneum. — The peritoneum is the serous membrane
which lines the walls of the abdominal cavity, and gives more
or less complete coverings to all the viscera within it. In
the male it is a closed sac like other serous membranes. In
the female, however, there is a small opening at the extremity
of the Fallopian tube, by means of which the lumen of this tube
communicates with the interior of the sac. It differs from
other serous sacs in its great size, and also in its many com-
plications. Take, for example, the pleura or the serous peri-
cardium, or the tunica vaginalis ; in these cases the serous
membrane lines a cavity which holds a single viscus, and the
reflection of the membrane from the walls of the cavity on
to the viscus, and from the viscus again on to the walls, can
be followed with the greatest ease. The peritoneal sac, on
the other hand, belongs to a cavity which contains numerous
viscera, the majority of which have undergone striking changes
in form and in position during development ; this is the
reason why its arrangement is so complicated.
In opening the cavity of the abdomen, the peritoneal sac
has been laid open, and the inner surface of the membrane
is observed to present the usual smooth, polished, and
glistening appearance. The part which lines the walls of
the abdomen is termed the parietal peritoneum ; that which
is reflected on to viscera is called the visceral peritoneum.
ABDOMINAL CAVITY
43i
Before tracing the peritoneum through its many foldings,
it is well that some terms which are applied to certain of its
folds should be explained. The term omentum is employed
to denote a fold of peritoneum which connects the stomach
with neighbouring viscera. Thus we have the great or gastro-
Lesser omentum
Great omentum
Small intestine
— Liver
Small sac
Foramen of
Winslow
Pancreas
Duodenum
Transverse colon
Mesentery proper
_Rectum
Pouch of Douglas
Fig. 164. — Diagram to illustrate the continuity of the Peritoneum in the
vertical direction in the Female. (Birmingham.)
colic omentum connecting it with the transverse colon ; the small
or gastro-hepatic omentum connecting it with the liver ; and the
gastro-splenic omentum connecting it with the spleen. The
term mesentery is applied to any fold of peritoneum which
attaches a part of the intestinal tube to the posterior wall
of the abdomen, and conveys to it its blood-vessels, as, for
example, the mesentery proper in connection with the small
432 ABDOMEN
intestine, the transverse meso- colon, the pelvic meso -colon, the
mesentery of the vermiform appendix, and the mesenteries
occasionally found in connection with the ascending and
descending portions of the colon. The term ligament is
given to folds which connect viscera which are not parts
of the intestinal canal to the walls of the abdomen, or
which bind viscera of any kind to the diaphragm. Examples
of these are to be found in the peritoneal ligaments of the
liver, bladder, and uterus, and also in the lieno-renal, the
phrenico-colic, and the gastro-plu'enic ligaments.
Let us now endeavour to follow the peritoneal membrane
in the vertical direction (Fig. 164). The best point to start
from is the great omentum, or large apron -like fold which
hangs down from the stomach, and is spread out over the
coils of the small intestine. This omentum is composed of
four layers — two anterior layers and two posterior layers, and
these are continuous with each other at the lower free margin
of the fold. Trace the two anterior layers upwards. They
lead to the greater curvature of the stomach, and here they
separate from each other so as to enclose this viscus between
them — one passing in front and the other passing behind it.
The smooth glistening appearance presented by the surface of
the stomach is due to the peritoneal coating which it thus
acquires. At the lesser curvature of the stomach the two
layers come together, and are prolonged upwards to the liver
as a distinct fold, which receives the name of the gastro-hepatic
or lesser omentum. Reaching the transverse fissure of the
liver the two layers again separate, this time to enclose the
liver. The one layer is directed forwards over the under
surface of the organ, round its anterior border, and then
onwards over its anterior and superior surfaces. On reaching
the point where the liver and diaphragm are in immediate
contact and held together by intervening areolar tissue, it
is reflected on to the diaphragm, and proceeds forwards upon
its under surface to reach the anterior wall of the abdomen.
The other layer turns backwards, and, clothing the lobus
Spigelii on the posterior surface of the liver, is reflected on to
the back part of the diaphragm, and turns downwards on the
posterior wall of the abdomen. We shall now leave these
layers for a little and trace the two posterior layers of the
omentum. For this purpose it is necessary to turn up the
great omentum over the ribs. Its two posterior layers in pro-
ABDOMINAL CAVITY 433
ceeding upwards come to the transverse colon. This they
enclose, the one passing in front and the other behind,
and coming in contact with each other again on the
other side of the gut, they are prolonged backwards to the
posterior wall of the abdomen, as the transverse meso-colon.
They reach the back wall of the abdomen along the anterior
border of the pancreas, and here they separate. The one
layer is carried backwards and upwards over the upper
surface of the pancreas to become continuous with the layer
which we left upon the posterior wall of the abdomen.
The other turns downwards over the third part of the
duodenum, and is almost immediately led away from the
posterior wall of the abdomen by the superior mesenteric
vessels, which, spreading out in a fan-like manner, conduct it
to the small intestine. Turning round the gut so as to invest
it, the peritoneum proceeds upwards upon the posterior aspect
of the superior mesenteric vessels to the spine. In this
manner the ?nesentery proper is formed. The peritoneum is
now carried downwards over the posterior abdominal wall into
the pelvis, where it may be traced over the pelvic colon,
rectum, and bladder,1 to which it gives coverings, and then
on to the anterior abdominal wall, where it becomes continu-
ous with the layer which we left there.
The tzuo anterior layers of the great omentum, therefore,
proceed upwards to the under surface of the diaphragm, and
there separate, the one passing forwards over the anterior
portion of its under surface to reach the anterior wall of the
abdomen, whilst the other is directed backwards over the
posterior part of its under surface to reach the posterior wall
of the abdomen. On their way up to the diaphragm these
layers enclose the stomach, form the gastro-hepatic omentum,
and partially enclose the liver. On the other hand, the two
posterior layers are directed backwards to the spine, and there
separate. In passing back, they enclose the transverse colon,
form the transverse meso-colon, and partially enclose the
pancreas. The one layer then ascends to become continuous
with the layer on the posterior abdominal wall. The other
layer passes downwards, doubles upon itself to enclose the
1 In the female it also gives a covering to the uterus, but the disposition
of the peritoneum in the pelvis, both male and female, will be fully described
in connection with the pelvic viscera.
VOL. I — 28
434
ABDOMEN
small intestine and form the mesentery proper, enters the
pelvis, and then reaches the anterior abdominal wall.
A reference to Fig. 164 will show that the peritoneal cavity
is arranged in two sacs, — a large sac in front and a smaller sac
situated behind it. The large pouch is the one into which we
have opened in opening the cavity of the abdomen. Now it
must be clearly understood that these are simply compart-
,
Fig. 165. — Section through the Peritoneal Cavity at the
level of the Foramen of Winslovv.
Stomach.
Aorta.
Parietal peritoneum.
Spleen.
Twelfth D.V.
Right kidney.
Vena cava.
8. Foramen of Winslow.
9. Portal vein.
10. Common bile duct.
11. Hepatic artery.
12. Ligamentum teres,
13. Gastro-hepatic omentum.
ments of one serous sac, and that they communicate with
each other through a narrow channel called the Foramen of
Winslow (foramen epiploicum). The best way to find the
foramen of Winslow is to lay hold of the fundus of the gall-
bladder with the left hand, and then pass the forefinger of
the right hand backwards along it towards its neck. The
finger will slip behind the gastro-hepatic omentum into the
foramen.
The foramen of Winslow has the following boundaries : —
ABDOMINAL CAVITY
435
in front, the right free margin of the gastro-hepatic omentum,
between the two layers of which are the hepatic artery, the
portal vein, the common bile duct, and some nerves ; behind,
the vena cava inferior, and the right crus of the diaphragm,
covered by peritoneum ; below, the duodenum and hepatic
artery ; and above, the lobus caudatus of the liver.
The lesser bag of the peritoneum extends downwards into
Fig. 106. — Section at the level of the Umbilicus through
the Intervertebral Disc between the third and fourth
lumbar vertebrae.
.1. Small intestine.
2. Aorta.
;. Ureter.
4. Descending colon.
5. Spinous process of third L.V
6. Ascending colon.
7. Vena cava.
S. Mesentery.
the omentum, upwards in relation to the posterior surface of
the Spigelian lobe of the liver and back part of the diaphragm,
and to the left as far as the spleen. It is closed in the
following manner : — in front, by the two anterior layers of
the great omentum, by the stomach, by the gastro-hepatic
omentum, and the lobus Spigelii of the liver ; behind, by the
two posterior layers of the great omentum, by the transverse
colon, by the transverse meso- colon, and by the layer which
ascends on the posterior wall of the abdomen over the
1— 28 a
436 ABDOMEN
pancreas, left kidney, left suprarenal capsule, and diaphragm :
on the left side, by the spleen and gastro-splenic omentum.
In a favourable subject these points can be made out by dividing the
two anterior layers of the great omentum along the greater curvature of
the stomach, and introducing the hand into the lesser sac. The entire
extent of the pouch can thus be explored, and its continuity with the
greater bag demonstrated, by turning the forefinger to the right and
bringing it out through the foramen of Winslow, or by passing the fore-
finger of the other hand into the foramen of Winslow, and making, the
two fingers meet behind the gastro-hepatic omentum.
The peritoneal lining of the abdomen must also be traced
in the transverse direction at different levels. Fig. 165 gives a
diagrammatic view of the manner in which it is arranged at
the level of the foramen of Winslow or the twelfth dorsal
vertebra. Taking the gastro-hepatic omentum as the starting-
point, follow the two layers of wrhich this is composed to the
right. They become continuous around the hepatic artery
and common bile duct and the portal vein forming the right
free border of this omentum and the anterior boundary of the
foramen of Winslow7. Following them to the left, they separate
to enclose the stomach, and then, coming in contact again,
they are prolonged to the spleen in the form of the gastro-
splenic omentum. Here they separate, and the posterior of
the two layers is reflected backwards to the anterior surface
of the left kidney, so as to form the right layer of a fold
called the lieno-renal ligament. Upon the kidney it turns to
the right, and is continued over the posterior wall of the
abdomen until it reaches the foramen of Winslow, of which it
forms the posterior boundary. Here it covers the vena cava
inferior, and is then carried onwards over the right kidney
on to the lateral and the anterior wall of the abdomen. The
anterior layer of the gastro-splenic omentum, which we left at
the spleen, turns round this organ so as to give it its serous
covering, and, reaching again its inner or visceral aspect, it is
reflected backwards to the left kidney, forming the left layer of
the lieno-renal ligament. Upon the anterior surface of the kidney
it turns to the left, and, reaching the wall of the abdomen, is
continued round this to become continuous with the layer
which we left there. Observe that at this level the peritoneum
is borne off the anterior wall of the abdomen by the obliterated
umbilical vein, so as to form a distinct fold, called the falciform
ligament of the liver.
In the diagram which is given to illustrate the continuity
ABDOMINAL CAVITY 437
of the peritoneum at this level (Fig. 165), the continuity of
the lesser and greater bags of the peritoneum through the
foramen of Winslow is seen. The gastro-splenic and the
lieno-renal folds which connect the spleen to the stomach
and to the left kidney are also exhibited.
Opposite the umbilicus, at the level of the intervertebral
disc, between the third and fourth lumbar vertebrae, the
peritoneum may be followed in the transverse direction
with the greatest ease (Fig. 166). Turn the great omentum
with the enclosed transverse colon upwards over the ribs,
and, taking the mesentery proper as the starting-point, trace
its two layers towards the small intestine. They will be
observed to be continuous around it. Now follow them
backwards to the spine, and here they will be observed to
separate — the one turning to the right, and the other to
the left over the posterior wall of the abdomen. In the
lumbar regions they meet the ascending and descending
portions of the colon. These they clothe anteriorly and
laterally, as we have already seen, and then they are carried
on to the anterior wall of the abdomen, where they become
continuous.
As we have previously observed, the ascending and
descending portions of the colon may be completely en-
veloped by peritoneum, and even connected by mesenteries
to the posterior wall of the abdomen. Symington states, with
good reason, that the frequency of these mesenteries has
been much exaggerated.
Peritoneal Ligaments. — In the abdomen proper, the
student must specially examine — (1) the gastro-phrenic
ligament; (2) the lieno-renal ligament; (3) the phrenico-
colic ligament ; and (4) the hepatic ligaments.
The gastrophrenic ligament is an insignificant fold which
connects the fundus of the stomach with the under surface
of the diaphragm. It is placed close to the oesophageal
opening, on its left side, and is formed by that layer which
ascends over the anterior surface of the fundus of the
stomach to reach the diaphragm. It is simply a reduplication
of this layer.
It is interesting to note that the stomach is not completely covered by
peritoneum. There is a small triangular area situated on its posterior
surface immediately below the oesophagus, which is bare, and rests directly
upon the left crus of the diaphragm.
1—28?)
438 ABDOMEN
The lieno-renal ligament, formed of two layers of peritoneum,
passes from the visceral face of the spleen to the front surface
of the left kidney. It is a short fold, and between its two
layers the branches of the splenic artery reach the hilum of
the spleen (Fig. 165).
The phrenico- colic liga?nent has been already noticed (p. 428).
The ligaments of tlie liver are five in number — viz., (1)
the ligamentum teres; (2) the falciform ligament; (3) the
coronary ligament; (4) the right lateral; and (5) the left lateral
ligaments.
The ligamentum teres is not a peritoneal ligament, but it is
convenient to describe it at the present stage. It is a fibrous
cord, in fact the obliterated umbilical vein of the foetus, which
extends from the umbilicus upwards and backwards to the
anterior part of the longitudinal fissure on the under surface of
the liver. It ends by joining the wall of the left terminal
branch of the portal vein.
The falciform ligament (ligamentum falciforme hepatis) is
a double layer of peritoneum of a triangular shape. By its
anterior border it is attached to the anterior wall of the
abdomen, and to the under surface of the diaphragm, whilst
by its posterior border it is fixed to the upper and anterior
surfaces of the liver, so as to mark it off into a right and
left lobe. Its lower border or base is free, and contains between
its two peritoneal layers the ligamentum teres. Along the
line of its attachment to the liver the two layers of peri-
toneum which compose it separate — the one spreading over
the left lobe and the other over the right lobe. When followed
backwards these leave the liver and pass on to the diaphragm
as upper layers of the coronary and lateral ligaments
(Fig- i56> P- 412).
The ligamentum teres instead of following the long and circuitous route
represented by the attachment of the falciform ligament to the parietes and
the liver takes a short cut from the umbilicus to the under surface of the
liver and drags away, as it were, from the front wall of the abdomen and
the diaphragm the two peritoneal layers which form the falciform ligament.
To understand the coronary ligament (ligamentum coron-
arium hepatis) aright, it must be borne in mind that an irregular
area on the posterior surface of the right lobe of the liver is
devoid of peritoneum, and that this area is in direct apposition
with the diaphragm, to which it is connected by some loose
areolar tissue. The peritoneum covering the upper surface
ABDOMINAL CAVITY 439
of the liver is reflected at the upper limit of this bare area
directly on to the diaphragm ; this reflection constitutes the
upper layer of the coronary ligament. The lower layer of the
ligament is formed at the lower limit of the bare area by the
reflection of the peritoneum from the under surface of the liver
on to the upper part of the right kidney and the vena cava
inferior. The two layers, therefore, of the coronary ligament
are not in contact with each other, but are separated by a
distance equal to the breadth of the bare surface of the liver
(Figs. 156 and 182, pp. 412 and 480).
The right lateral ligament (ligamentum triangulare dextrum)
will be brought into view by dragging the right lobe of the
liver to the left and looking into the interval between the back
part of its right surface and the diaphragm. It is a very small
free fold, formed by the apposition of the two layers of the
coronary ligament at the right extremity of the bare area of
the liver (Fig. 182, p. 480).
The left lateral ligament (ligamentum triangulare sinistrum)
is a much more extensive fold, which passes from the under
surface of the diaphragm to the posterior part of the upper
surface of the left lobe of the liver. It is triangular in form, and
its basal margin is crescentic and free and directed to the left.
When the ligament is traced to the right its upper layer is seen
to become continuous with the left layer of the falciform liga-
ment, whilst the lower layer becomes continuous with the front
layer of the gastro-hepatic omentum (Fig. 182, p. 480).
Peritoneal Omenta. — These are three in number — viz., the
great omentum, the small omentum, and the gastro -splenic
omentum.
The great omentum (omentum majus) is as a rule by far the
largest free fold of peritoneum in the abdomen. It is formed
by the two layers which invest the stomach and first part of
the duodenum passing downwards for a variable distance and
then being folded backwards upon themselves to gain the
transverse colon. In the adult, especially towards its lower
free margin, the four layers have become blended, so that it
is impossible to separate them. The cavity of the lesser
peritoneal bag is carried downwards into it. In obese people
the whole structure becomes loaded with fat.
The small or gastro - hepatic omentum (omentum minus),
formed of two layers, leaves the lesser curvature of the
stomach and the first part of the duodenum, and proceeds
44° ABDOMEN
upwards as a free fold towards the liver. x\bove it is attached
along the transverse fissure of the liver, the posterior part of
the longitudinal fissure of the liver [i.e., that part which
contains the obliterated ductus venosus) (Fig. 182), and also
to the diaphragm in the immediate vicinity of the oesophagus.
It presents a right free margin, which extends from the trans-
verse fissure of the liver to the duodenum, and forms the
anterior boundary of the foramen of Winslow. Over the
greater part of its extent it is very thin ; the two layers are
fused, and often it is fenestrated. The two layers, however,
become evident along its lines of attachment, and also in the
portion adjoining its right free edge.
The gastro- splenic omentum, composed of two peritoneal
layers continuous with the two anterior layers of the great
omentum, forms a short fold, which connects the fundus
of the stomach with the gastric surface of the spleen immedi-
ately in front of its hilum. Between its two layers the vasa
brevia of the splenic artery gain access to the stomach.
Mesenteries of the Great Intestine. — Under ordinary cir-
cumstances these are three in number — viz., the meso-
appendix, the transverse meso-colon, the pelvic meso-colon.
The transverse meso-colon (mesocolon transversum) stretches
from the transverse colon to the posterior wall of the abdomen,
to which it is attached along the anterior border of the pancreas
(Fig. 160, p. 419). It is an extensive fold, formed by the two
posterior layers of the great omentum after they have enclosed
the colon, and containing between them the blood-vessels
which go to this portion of the gut. It is longest in the mesial
plane of the body, and shortens as it is traced to the right and
to the left, until finally at the two flexures which mark the
limits of the transverse colon it ceases to exist as a free fold.
The pelvic meso-colon varies considerably in different
subjects not only in its length and extent, but also in the
manner in which its root is attached to the pelvic wall.
It is composed of two layers, between which the sigmoid
arteries run towards the portion of the colon which they
enclose. The root of the pelvic meso-colon is as a rule fixed
to the pelvic wall along a line which is bent sharply on
itself. This attachment begins on the inner aspect of the
left psoas muscle and runs upwards and inwards in the
direction of the pelvic brim and along the inner aspect of the
external iliac vessels. Having gained a point on the inner
ABDOMINAL CAVITY
441
side of the left common iliac artery, it turns abruptly down-
wards over the promontory of the sacrum and along the
middle of the anterior surface of that bone as far as the third
sacral vertebra. Here the mesentery ends by its two layers
separating from each other in such a way as to leave the
posterior surface of the rectum bare. The superior hsemor-
DuoDENO-.
JEJUNAL FLEX:
Fig. 167. — The Mesentery in a subject which was hardened by formalin
injection. The jejunum and ileum have been removed, and the foldings
of the mesentery are displayed.
rhoidal artery runs downwards in the vertical part of the root
of the pelvic meso-colon, while the lower sigmoid arteries
enter the mesentery through the upper oblique part of the root.
The pelvic meso-colon includes both the sigmoid meso-colon and the
meso-rectum of the older descriptions. It should be noted that when the
pelvic colon with its mesentery is drawn out from the pelvis and extended
to its full length, it presents a somewhat pedunculated appearance, and
442 ABDOMEN
cases of intestinal obstruction through twisting of this loop of colon around
its own root or base are not unknown.
Mesentery of the Small Intestine. — The mesentery proper
is an extensive fold of peritoneum by which the jejunum and
ileum are suspended from the posterior wall of the abdomen.
To obtain a proper viewr of this fold it is necessary to throw
up the great omentum and the transverse colon over the
lower margin of the chest. The mesentery proper is attached
along an oblique line, which extends from the left side of the
body of the second lumbar vertebra downwards, and to the
right into the right iliac fossa (Fig. 168). The portion of
the mesentery immediately adjoining this attachment is very
thick and is called the " root " of the mesentery. As this is
traced downwards it will be seen to cross obliquely the third
part of the duodenum, the aorta, the vena cava, and the right
psoas muscle. The " root " of the mesentery is thus, com-
paratively speaking, short (about six inches), but, as the fold
approaches the coils of the small intestine, it widens out
enormously, so that when it reaches the gut its width equals
the length of the jejunum and ileum. This great wTidth is
not at first apparent, because the mesentery is thrown into
folds like a goffered frill (Fig. 167). The coiled condition of
the gut is due to this arrangement. The mesentery is thus
markedly fan-shaped, and its length from its root to the
intestine at its longest part is about six inches.
The twro layers of the mesentery are not in apposition
with each other. They are separated by a variable amount
of fat, and also certain important structures which lie between
them. These are (1) the superior mesenteric vessels and their
branches to the jejunum and ileum ; (2) the superior mes-
enteric nerves ; (3) great numbers of lymphatic glands and
lacteal vessels ; (4) the gut itself.
Subdivision of the Peritoneal Cavity.— The peritoneum may be
regarded as forming a huge lymph sac behind which the various
abdominal viscera are situated. It possesses absorptive properties in a
high degree partly through the activities of its living endothelial cells and
partly by means of lymphatic vessels which in certain localities open
directly on its surface by minute orifices termed stomata.
From the surgical point of view it is important to note that the peritoneal
cavity is subdivided into certain definite compartments. The transverse
colon with its mesentery forms a horizontal partition which stretches
across the abdomen at the level of the second lumbar vertebra and
forms the floor of an upper compartment and the roof of a lower
compartment.
ABDOMINAL CAVITY
443
The upper compartment of the peritoneal cavity is bounded above by the
peritoneum clothing the diaphragm, and the peritoneum which forms its
walls is related to the spleen, stomach, liver, gall-bladder and bile ducts,
portion of the duodenum, the pancreas, upper portions of the kidneys
and the suprarenal capsules. The chief artery in relation to this sub-
division is the coeliac axis which supplies the liver, stomach, spleen,
pancreas and portion of the duodenum.
Transverse
, colon
Fpper Com-.
l'ARTMENT
Hepatic
flexure
of colon
Lower
COMPART-
MENT (right
subdivision)
Ascending
colon' fflf
Ca-cum
Vermiform /£\
appendix
(cut across)
Splenic flexure
of colon
Lower Com-
partment (lef
subdivision)
Descending
:olon
Ileum'
Fig. 168
Iliac colon
Mesentery
proper (cut acr(
at the root)
Pelvic colon
-Diagram to show compartments of the Peritoneal Cavity
of abdomen.
The lower compartment of the peritoneal cavity is subdivided into a
right and a left portion by the mesentery of the small intestine. The
right subdivision is narrow below in the region of the caecum but expands
as it is followed upwards. Its bounding peritoneum is in relation to the
oecum and vermiform appendix, ascending colon, lower part of the right
kidney and its ureter, lower part of the duodenum, and a variable number of
the coils of the small intestine. The larger left subdivision of the lower
compartment is narrow above and widens out below where it becomes
continuous with the cavity of the pelvis. It contains the duodeno-jejunal
flexure, the greater proportion of the coils of the small intestine, the
descending colon, the iliac colon, and the lower part of the left kidney
with its ureter.
444 ABDOMEN
The artery specially associated with the lower peritoneal compartment is
the superior mesenteric, the branches of which supply the greater part of
the intestinal canal.
Occasional Peritoneal Fossse. — It is necessary to take notice at this
stage of certain peritoneal pockets or blind recesses which are occasionally
present in different positions on the posterior wall of the abdomen. There
are three localities in which these fossae may be found : (i) in the neighbour-
hood of the caecum ; (2) in relation to the duodeno-jejunal flexure ; and (3)
in the root of the pelvic meso-colon.
There are several forms of fossae in the region of the caecum. By raising
up the caecum a fossa may sometimes be seen to ascend either behind the
inner or outer part of the lower portion of the ascending colon. Peritoneal
pouches of this kind are termed retrocolic fossa, and within such recesses
when they exist the vermiform appendix frequently lies. Another form of
fossa in this neighbourhood is where a small peritoneal recess is found on
the inner side of the great intestine immediately above or immediately
below the ileo-caecal junction. The term ileo-colic is applied to the former,
and ileo-ccecal to the latter.
The region immediately to the left of the duodeno-jejunal flexure must
also be explored for occasional peritoneal fossae. One in relation to the
summit of the flexure, which looks downwards and is termed the superior
duodenal fossa, was present in 50 per cent of thesubjects examined by Jonnesco;
another, a little lower down and with its mouth directed upwards, may lie
on the left side of the terminal part of the duodenum ; this is called the
inferior duodenal fossa. It is found in 75 per cent of subjects dissected
(Jonnesco).
A third peritoneal pouch in this neighbourhood, termed the para-duodenal
fossa, is sometimes formed by a small fold of peritoneum being raised from
the back wall of the abdomen by the inferior mesenteric vein. It lies a
little to the left of the terminal part of the duodenum.
Other varieties of peritoneal fossae in this region are described.
The fossa intersig/noidea is not often seen in the adult. When present it
will be found by raising the pelvic loop of the great intestine. Its mouth lies
about the middle of the under surface of the root of the pelvic meso-colon.
Dissection. — The structures which are included between the two layers
of the mesentery proper and between the two layers of the transverse
meso-colon must now be dissected. The great omentum being thrown
well up over the lower margin of the chest, remove the entire anterior
layer of the mesentery from its root down to where it is attached to the gut.
Begin at the upper end of the jejunum at the left side of the second lumbar
vertebra, and gradually travel downwards to the lower end of the ileum,
stripping off the peritoneum and cleaning the structures exposed. To
display all the branches of the superior mesenteric artery it is necessary
to remove also the inferior layer of the transverse meso-colon and the
peritoneum which proceeds on the posterior wall of the abdomen towards
the caecum and ascending colon. Follow the main trunk of the superior
mesenteric artery upwards to its origin from the aorta, by raising the
lower border of the pancreas.
Superior Mesenteric Artery (arteria mesenterica superior).
— The superior mesenteric artery springs from the front of
the abdominal aorta about a quarter of an inch below the
cceliac axis. At its origin it is covered by the neck of the
ABDOMINAL CAVITY
445
pancreas, and crossed by the splenic vein. Emerging from
under cover of the pancreatic neck it proceeds downwards
in front of a portion of the head of the pancreas, crosses the
third part of the duodenum, close to the duodeno -jejunal
Fig. 169. — Dissection of the Superior Mesenteric Artery.
flexure, and then enters the mesentery proper. Between the
two layers of the mesentery the artery is placed at a short
distance from the mesenteric root, and pursues a slightly
curved course towards the right iliac fossa, where it ends by
anastomosing with one of its own branches. The convexity of
446 ABDOMEN
the curve which it describes is directed to the left, and the
concavity to the right. It is accompanied by the superior
mesenteric vein, which lies upon its right side, and by the
superior mesenteric plexus of nerves which surrounds it closely.
The following branches proceed from the superior mes-
enteric artery : —
i. Inferior pancreaticoduodenal.
2. Branches to the jejunum 1 -p, . ,. . ,
, ., J J J- Rami intestini tenuis.
and ileum. J
3. Branches to the great/ ggj^
destine. { Mi*ddle colk
The inferior pancreatico - duodenal (arteria pancreatico-
duodenalis inferior) takes origin from the upper part of the
superior mesenteric artery and passes upwards and to the
right behind the head of the pancreas. It gives branches
both to the duodenum and the pancreas and anastomoses
with the superior pancreatico-duodenal artery.
The rami intestini tenuis (arterise intestinales) spring from
the convexity or left side of the superior mesenteric, and
proceed obliquely downwards and to the left, between the
layers of the mesentery, to supply the jejunum and ileum.
They are very numerous, from twelve to fifteen, or even more,
in number, and, by their mutual inosculations, they form a
very remarkable succession of arches before they finally reach
the bowel. At first they run parallel to one another, but
soon they divide into two branches, each of which joins its
neighbour, and in this way a series of arterial arcades is
formed. From these smaller vessels proceed, which divide
and unite in a similar manner to form a second series of
arches, and so on, until three, four, or perhaps even five tiers
of arterial arcades are produced. From the lowest arches a
multitude of small branches pass directly to the wall of the
intestine. Here, along the line of mesenteric attachment,
they divide, and the minute twigs thus derived pass trans-
versely round the gut so as to encircle it. At first they lie
subjacent to the peritoneal coat, but soon they seek a deeper
plane in the wall of the intestine, and ultimately reach the
submucous coat.
The colic branches (arterise colicae) spring from the concavity
or right side of the superior mesenteric artery.
The ileo-colic artery (arteria ileo-colica), the lowest of the
ABDOMINAL CAVITY 447
three branches which go to the great intestine, proceeds down-
wards and outwards towards the right iliac fossa. It is placed
behind the parietal peritoneum, and divides into an ascending
and a descending or ileo-caecal branch. The ascending branch
turns upwards, inosculates with a branch of the right colic,
and from the arterial arch thus formed branches are given to
the ascending colon. The descending branch, sometimes called
the ileo-ccecal artery, proceeds to the upper part of the ileo-
caecal junction and sends branches in different directions.
Two, termed the a?iterior and posterior caical arteries, pass
respectively to the front and back of the caecum ; one, a
long slender vessel, the artery to the appendix, runs downwards
behind the terminal part of the ileum and enters the meso-
appendix for the supply of the vermiform appendix ; whilst
a fourth, the ileal artery, turns to the left along the ileum,
and forms a loop with the termination of the superior mes-
enteric trunk.
The right colic artery (arteria colica dextra) frequently arises
in common with the ileo-colic. Escaping from the root of
the mesentery it takes a horizontal course to the right, behind
the parietal peritoneum on the back wall of the abdomen,
and divides into two branches, a superior and an inferior.
The superior branch ascends between the two layers of the
transverse meso-colon to inosculate with the middle colic ;
whilst the inferior branch joins the ascending part of the
ileo-colic. From the convexity of these arches twigs proceed
to the colon.
The middle colic artery (arteria colica media) is the highest
of the three branches which spring from the concavity of
the superior mesenteric. It passes between the two layers
of the transverse meso-colon, and divides into a right and a
left branch. The right branch joins the superior part of the
right colic, whilst the left branch inosculates with the ascending
part of the left colic artery, which is derived from the inferior
mesenteric. Arterial arcades are thus formed in the transverse
meso-colon, from which branches proceed for the supply of
the transverse colon.
Superior Mesenteric Vein (vena mesenterica superior).—
This large vein lies to the right of the superior mesenteric
artery, and receives tributaries, which come from those parts of
the intestinal canal which are supplied by branches from the
superior mesenteric artery, and also the right gastro-epiploic
448 ABDOMEN
vein from the great curvature of the stomach. Leaving the
mesentery, it passes upwards in front of the duodenum, and
then disappears under cover of the neck of the pancreas.
Here it unites with the splenic vein to form the vena porta. •
Superior Mesenteric Nervous Plexus (plexus mesentericus
superior). — This is a dense plexus of sympathetic twigs, which
surrounds the superior mesenteric artery like a sheath. From
it filaments are prolonged to the gut along the various
branches of the artery. As the nerves approach the bowel,
some of the twigs leave the vessels and effect a series of com-
munications with each other in the intervals between the
arteries.
The superior mesenteric plexus is an offshoot from the
solar plexus, and it distributes twigs to the jejunum, ileum,
and to the right half of the great intestine.
Mesenteric Lymphatic Glands (lymphoglandulae mesen-
tericae). — These are very numerous, indeed considerably over
a hundred in number. In health they rarely attain a size
greater than that of a small bean or a pea, and they are scattered
between the two layers of the mesentery. The larger glands
lie along the superior mesenteric artery, whilst the others are
placed in the intervals between its branches. It should be
noted that they are most numerous opposite the jejunum, and
that the mesentery in the immediate vicinity of the gut is free
from them.
A few lymphatic glands will also be noticed in connection
with the great intestine.
The lacteal vessels enter the mesentery from the walls of
the intestine in enormous numbers. As they proceed up-
wards they pass through the succession of glands which they
meet, and greatly reduced in number, although considerably
enlarged in calibre, they usually terminate near the origin of
the superior mesenteric artery in one or perhaps more trunks
which pour their contents into the receptaculum chyli of the
thoracic duct.
Dissection. — The coils of the small intestine must now be pulled over to
the right side of the body, and the peritoneum carefully removed by the
fingers from the lower part of the aorta and the left side of the spine and
psoas muscle. The inferior mesenteric artery is thus exposed, and its
branches can be followed to their distribution. The ureter and the
inferior mesenteric vein will be seen lying upon the psoas muscle.
Inferior Mesenteric Artery (arteria mesenterica inferior).
ABDOMINAL CAVITY
449
— The inferior mesenteric artery, considerably smaller than
the superior mesenteric, springs from the left side of the
abdominal aorta, about an inch and a half above its terminal
bifurcation, and descends with a slight inclination to the left.
APPENDIXt-t
Fig. 170. — Dissection of the Inferior Mesenteric Artery.
towards the left iliac fossa. At first it is applied to the left
side of the aorta, to which it is bound by peritoneum ; it then
crosses the left common iliac artery and enters the pe'
where it receives the name of superior hamotrhoidal. Before
leaving the abdomen proper it gives off the left colic and the
sigmoid branches.
vol. 1
45o ABDOMEN
The left colic artery (arteria colica sinistra) proceeds to
the left, over the left kidney, and divides into two branches,
of which one ascends in the transverse meso-colon to in-
osculate with the middle colic, whilst the other descends
behind the peritoneum lining the posterior wall of the abdomen
to unite with the superior sigmoid artery. From the arches
thus formed twigs are supplied to the transverse and the
descending colon.
The sigmoid arteries (arteriae sigmoideae), two or three in
number, are distributed to the lower part of the descending
colon, the iliac colon and the pelvic colon. The highest
branch enters the left iliac fossa behind the parietal peri-
toneum and sends a branch upwards to form an arch with
the descending branch of the left colic, and another down-
wards, which ultimately enters the pelvic meso-colon and
joins the other sigmoid branches. The lower sigmoid
arteries pass into the pelvic meso-colon, and there form a
series of arcades (varying in number according to the length
of this mesentery), from which the twigs for the supply of the
pelvic colon are given off.
The superior hemorrhoidal artery will be followed out in
the dissection of the pelvis.
Inferior Mesenteric Vein (vena mesenterica inferior). —
This vein receives tributaries corresponding with the branches
of the inferior mesenteric artery. It passes upwards upon
the psoas muscle under cover of the peritoneum, to the left
of, and at some distance from, the artery, and, disappearing
behind the pancreas, it ends in the splenic vein.
Inferior Mesenteric Plexus of Nerves (plexus mesentericus
inferior). — This is an offshoot from the left side of the aortic
plexus. It closely surrounds the artery, and sends twigs
along the branches of the vessel to supply the left half of
the great intestine.
Dissection. — If the peritoneum has been carefully stripped off the lower
part of the aorta, there will be little difficulty in recognising and following
out the delicate nerves which form the aortic plexus. Raise the third part
of the duodenum from the surface of the aorta, and trace these nerve
twigs upwards.
Aortic Plexus of Nerves (plexus aorticus abdominalis). —
The aortic plexus is placed upon the aorta between the origins
of the two mesenteric arteries. It is more strongly marked
upon the sides of the artery than in front of it. Superiorly it
ABDOMINAL CAVITY 451
will be found to be continuous with the solar and renal
plexuses, whilst inferiorly it sends several large branches
downwards in front of the common iliac arteries to join the
hypogastric plexus — a plexus which is situated in front of the
fifth lumbar vertebra, and which will be afterwards dissected.
Upon each side, the aortic plexus will be observed to be
reinforced by several small twigs from the gangliated cord of
the sympathetic. The inferior mesenteric plexus accompanying
the artery of that name, and the spermatic (or ovarian) plexus
of nerves which accompanies the spermatic (or ovarian)
artery, are offsets from it.
Removal of the Intestines. — The jejunum, ileum, caecum, and colon
may now be removed from the abdominal cavity. Apply two ligatures
around the upper end of the jejunum, about an inch or so below the
duodenojejunal flexure, and divide the gut between them ; then place two
ligatures around the middle of the pelvic colon, and divide it in like
manner. The entire intestinal canal, with the exception of the duodenum,
the lower part of the pelvic colon, and the rectum, can now be taken away
by carefully severing the blood-vessels and peritoneal folds which hold it in
position. In cutting through the two layers of the great omentum, which
extend from the transverse colon to the stomach, keep the knife close to
the gut so as to avoid injury to the vessels in relation to the greater
curvature of the stomach.
As soon as the intestines are detached they should be taken to the sink
and the ligatures removed. The small intestine should be separated from
the great intestine by dividing the ileum about six inches from the point
where it enters the caecum, and, the remains of the mesentery having been
taken away from the small intestine by means of the scissors, both should
be thoroughly cleaned out by allowing the water from the tap to run freely
through them.
The coats of the small intestine should be dissected under water. Take
a few inches of the intestine from the upper end of the jejunum, and, having
opened it up with the scissors along the mesenteric line of attachment, pin
it out, with its mucous surface downwards, upon the bottom of a corkdined
tray, which has been previously filled with clean water. The jejunum is
chosen because its wall is thicker than the ileum, and consequently more
easily dissected. Carefully remove the thin serous coat in order that the
subjacent layer of longitudinal muscular fibres may be studied. Then turn
the specimen round and pin it down with its mucous surface uppermost.
Now remove the mucous membrane with the subjacent fiocculent submucous
coat with the scissors in one layer. The circular muscular fasciculi will
come into view.
Coats of the Small Intestine. — The small intestine has five
coats or strata entering into the formation of its walls, viz. : —
1. Serous. 4. Submucous.
2. Subserous. 5. Mucous.
3. Muscular.
The serous coating of the jejunum and ileum is complete,
except along the line of the mesenteric attachment. It is
exceedingly thin — much thinner than the layers of the
1—29 a
452 ABDOMEN
mesentery, with which it is continuous. Unless great care
be taken in stripping it off, some of the subjacent muscular
fibres will be taken away with it. The subserous coat is a
scarcely appreciable amount of areolar tissue which inter-
venes between the peritoneum and the muscular coat. It
need not be taken into account in this dissection. The
muscular coat is composed of involuntary, non- striated
muscular fibres. These are disposed in two layers, viz., an
external stratwn of longitudinal fibres, and an internal stratum
of circular fibres. Of these the circular layer is the thicker
and more distinct of the two. The external longitudinal
fibres are spread out in the form of a thin continuous layer all
round the circumference of the gut. In that part of the wall
opposite the mesenteric attachment the fibres are more
thickly disposed than elsewhere. The submucous coat is com-
posed of loose areolar tissue which binds the muscular to the
mucous coat. It is more firmly connected with the latter.
The mucous coat must be examined throughout the whole
length of the jejunum and ileum.
Dissection. — The student has noticed that externally no distinction can
be drawn between the jejunum and ileum, with this one exception, viz.,
that as the tube descends it diminishes slightly in its calibre and in the
thickness of its walls. It is necessary, therefore, that he should open it up
along its whole length, with the view of determining what differences exist
internally. Before doing this, about twelve inches of the upper part of the
jejunum should be removed and inflated with air. It should then be hung
up to dry in order that the folds of mucous membrane, called valvule
conniventes, may be studied in their continuity. The best way to open the
remainder of the intestine is to tie a ligature around the lower cut end of
the ileum, and fill the gut as full as possible with water. The scissors can
now be easily carried along the line of the mesenteric attachment, and the
intestine slit open in its entire length. The intestine can be laid open with
much greater ease if a piece of costal cartilage be impaled upon that blade
of the scissors which is introduced into the gut.
Mucous Membrane of the Small Intestine. — The valvules
conniventes (plicae circulares) are the most conspicuous objects
on the inner wall of the small intestine. These are folds of
the mucous membrane placed more or less transversely to
the long axis of the gut. Note particularly that they are
per ma?ient folds, and that no amount of stretching or distension
of the walls will cause their obliteration. On careful study
of the dried specimen three main varieties of valvulae con-
niventes may be recognised. The great majority are in the
form of crescentic folds, which extend for a variable distance
round the wall of the gut ; others form complete rings around
ABDOMINAL CAVITY 453
the interior of the intestine ; whilst the third variety, and
usually the least numerous, are arranged in a spiral manner,
and take from one to three spiral turns around the wall of the
gut (Brooks and Kazzander). Each fold consists of two layers
of mucous membrane, with a little intervening areolar tissue
derived from the submucous coat. The other coats of the
intestine take no part in the formation of the valvulse con-
niventes. In the upper part of the jejunum the valvulse con-
niventes are strongly developed, and placed so closely together
that the intervals between them are hardly greater than the
thickness of one of the folds. As we follow them down,
however, they gradually diminish in numbers, become more
widely separated, more oblique in their direction, and not
nearly so prominent. Approaching the middle of the ileum,
they become exceedingly sparse and far between, and a little
beyond this they usually disappear altogether.
The chief function of the valvule conniventes is to increase the absorbing
and secreting surface of the small intestine.
Another peculiarity characteristic of the mucous lining of
the small intestine is the presence of villi (villi intestinales).
These are minute projections of the mucous membrane,
varying in length from about the ^th to ^th of an inch.
They occur in enormous numbers over the entire extent of
the inner surface of the gut, not only upon the valvulse con-
niventes, but also in the intervals between them, and they
give to the mucous membrane a velvety or fleecy appearance.
To obtain a proper view of these minute villous processes
it is necessary to float out a portion of the small intestine in
water, after it has been carefully cleansed from adhering mucus,
and examine it with an ordinary pocket-lens. If a portion
of the upper end of the jejunum be placed side by side with
a portion of the lower part of the ileum, and inspected in this
manner, the student will readily detect that the villi are, if
anything, larger, and that they are decidedly more numerous,
in the jejunum than in the ileum. They diminish gradually
in number and in size as we pass down the small intestine.
Peyer's patches and solitary glands must also be looked for.
Frequently they are difficult to find, but by holding the bowel
up to the light they can generally be detected. In our
examination of the Peyer's patches it is better to begin at the
lower end of the ileum and pass upwards.
454
ABDOMEN
Intermediate form
Solitary gland
A PeyeSs patch (noduli lymphatici aggregati) consists of
a large number of lymphoid follicles grouped together so as to
present to the eye a patch of an elongated, oblong figure.
The patches are placed upon that aspect of the gut which is
opposite to the line of the mesenteric attachment, and the
long axis of each corresponds in its direction with that of the
gut itself.
In the lower part of the
ileum the patches may present
a length of one, two, or even
four inches, and a breadth of
about half an inch, but, as we
follow them up the tube into the
jejunum, they become much
smaller and not nearly so num-
erous. The total number varies
much, but the average number
maybe stated to be about thirty.
They are more numerous in
the young, and not so abundant
nor so distinctly marked out in
later periods of life. Indeed,
in very old individuals they may
disappear almost entirely.
The solitary glands (noduli
lymphatici solitarii) are isolated
lymphoid follicles, scattered
everywhere over the mucous
membrane of the small intes-
tine. They are minute,
rounded or ovoid, opaque
Peyer's patch
Solitary glands
Fig. i7i.— Peyer's Patch and Soli- wnite bodies, about the size
tary Glands from the intestine of c .„ . , , ..
a child of two years old. (Bir- °f a millet Seed> and they
mingham.) usually cause a slight bulg-
ing of the mucous membrane
at the points where ■ they occur.
The valvular conniventes, the villi, and Peyer's patches are
the only special peculiarities of the mucous membrane of the
jejunum and ileum which are visible to the naked eye, and
from what has been said regarding them the dissector will
understand that although they are not arranged in such a
way as mark off by a clear line of demarcation the jejunum
ABDOMINAL CAVITY 455
from the ileum, they are sufficient to enable him to distinguish
between characteristic portions of each — i.e., between portions
taken at some distance from the arbitrary line of division. The
following are the essential points of difference which would
guide him in deciding which is ileum and which jejunum : —
Jejunum. Ileum.
Valvule Connivenles.
Numerous and well marked.
Numerous and large.
Few in number, small in size,
and, as a rule, nearly circular
in outline.
Few in number and poorly de-
veloped, and, in its lower part,
absent altogether.
Villi.
Not so numerous and not so
large.
Beyer's Patches.
More numerous, of large size, and
oblong in form.
Dissection. — -Ligature the great intestine about four inches above the
entrance of the ileum, and divide the gut above this point. The nozzle of
the bellows should now be introduced into the attached portion of ileum,
and the caecum inflated until its walls are tense. This portion of the
intestine should then be hung up to dry. Next slit open the colon in the
same manner as the small intestine, and examine its inner surface.
Great Intestine. — Transverse and oblique ridges or folds,
corresponding to the constrictions which separate the sacculi,
are everywhere apparent on the inner surface of the large
intestine. If the longitudinal bands of muscular fibres be
removed or divided at short intervals, and the gut stretched,
both sacculi and constrictions disappear, and the wall of the
bowel becomes uniform. The mucous membrane of the sreat
intestine is absolutely destitute of villi, but solitary glands are
present in considerable numbers. If the mucous surface be
examined with a lens, its surface will be seen to be studded
over with the round mouths of tubular glands, which are
embedded in the mucous membrane (crypts of Lieberkiihn).
The same glands are present in the mucous membrane of
the small intestine, but they are not so large.
Dissection. — The coats of the large intestine must be dissected in the
same manner as in the case of the small intestine.
Coats of the Large Intestine. — In connection with the
serous coat, the student has already taken notice of the appen-
dices epiploicic. The external longitudinal muscular fibres have
1—29 6
456
ABDOMEN
also been observed to be disposed in three flat bands. These
begin on the caecum at the base of the vermiform process.
From this they diverge, so as to take up positions on different
aspects of the gut. They are placed as follows: — (i) One
in relation to the attached surface; (2) the second upon the
anterior aspect; (3) and the third along the inner aspect of
the gut, but, in the case of the transverse colon, this band is
in relation to the inferior aspect of the tube. The internal
circular muscular fibres are most distinct in the constrictions
between the sacculi, but constitute a thin uniform layer over
Frenulum of valve
Anterior taenia coli
Upper segment
of valve
Frenulum of valve
Orifice of ileum
Inferior segment
of valve
Ileum
Taeniae coli
Orifice of appendix
Fig. 172.— Ccecum which has been distended with air and dried, and then
opened to show Ileo-Caecal Opening and Valve. (Birmingham.)
the entire extent of the gut. The submucous coat is in no
respect different from the corresponding coat in the small
intestine.
Dissection. — "When the distended caecum is dry, the ileo-caecal valve
should be examined. This can best be done by removing the outer wall
of the caecum with a pair of scissors. A window is thus made into the gut,
through which the opening of the ileum into the caecum can be seen.
Ileo-csecal Valve (valvula coli). — The ileo-caecal aperture
is a narrow transverse slit placed on the inner aspect of the
gut. The aperture is narrow and pointed behind, but more
open and wider in front. It is guarded by a valve which
consists of two crescentic segments or folds. The upper and
ABDOMINAL CAVITY
457
smaller segment is placed horizontally, whilst the lower one
is perpendicular. At the extremities of the aperture these
folds unite, and are prolonged round the inner surface of the
wall of the great intestine in the form of two ridges, which
are termed the frenula or retinacula of the valve. The point of
intersection of the Poupart and intertubercular planes marks
on the surface of the abdomen the position of the ileo-csecal
opening. A short distance below the ileo-caecal opening will
be seen the mouth of the vermiform appendix.
The above description relates to the ileo-caecal opening as seen in a
distended and dried specimen. In subjects in which the viscera have been
Upper segment
Orifice
Frenulum
Lower segment
Orifice of appendix
Fig. 173. — Ileo-Caecal Opening and Valve from a subject hardened,
by formalin injection. (Birmingham.)
hardened in situ by formalin the ileum presents the appearance of being
telescoped into the caecum in such a manner as to produce the upper and
lower folds which bound the slit -like ileo-caecal opening and form the
valve-flaps. This is particularly noticeable in the caecum of the child.
The peritoneum and the longitudinal muscular bands are in no way
involved in the infoldings which form the valve-flaps ; but the other
constituents of the gut-wall (viz., the mucous membrane, the submucous
coat, and the circular muscular fibres) take part in their formation. Villi
are present on the ileal but not on the caecal aspect of each valve-flap.
The function of this valve is obvious. It is so arranged that the free
passage of materials from the ileum into the caecum is in no way impeded ;
but when the caecum becomes distended, and there is consequently a
tendency to regurgitation, the frenula of the valve are put upon the stretch,
and the free borders of the segments brought into firm contact. In this
way reflux of the contents of the caecum into the ileum is prevented, although
it is well to note that the obliquity of the entrance of the ileum into the
caecum also exercises a very important influence in the same direction.
Structure of the Vermiform Appendix. — The serous coal
is complete, and the subjacent external longitudinal layer of
45*
ABDOMEN
the muscular coat forms a continuous and uniform covering
which at the base of the appendix becomes divided into the
three bands or taenia coli of the caecum. The internal
circular fibres of the muscular coat are likewise spread
uniformly and continuously over this part of the gut. The
distinguishing and important structural feature of the appendix
is found in the submucous coat. This coat is loaded with
lymphoid tissue which is arranged in numerous nodular
COELIAC AXIS
Fig. 174. — The Cceliac Axis System of Vessels.
masses, like solitary glands, and placed so closely together
that adjacent nodules in many cases become confluent with
each other. When the appendix is cut across and examined
under a low power of the microscope, these lymphoid follicles,
arranged in this manner, present a strong resemblance to
what is seen in a cross section through a Peyer's patch.
Dissection. — The cceliac axis, the artery which supplies blood to the
stomach, liver, duodenum, spleen, and pancreas, should now be dissected.
Pull the stomach downwards, and tear through the two layers of peritoneum
which form the gastro-hepatic omentum. The artery will be found by
dividing the layer of peritoneum which forms the posterior wall of the lesser
sac along the upper border of the pancreas. This dissection will be
facilitated if the liver is first raised and then fixed in this position, by
stitching it to the lower margin of the thorax.
ABDOMINAL CAVITY 459
Cceliac Axis (arteria cceliaca). — The cceliac axis is a short,
wide vessel, which springs from the front of the aorta, between
the two crura of the diaphragm, opposite and in immediate
relation to the upper margin of the pancreas. It is directed
horizontally forwards, and after a course of little more than
half an inch divides into three large branches, viz.: — (i) the
coronary; (2) the hepatic ; and (3) the splenic, which radiate
from each other like the spokes of a wheel. The cceliac
axis is surrounded by a thick, matted plexus of nerves, called
the cceliac plexus, which sends numerous nerve twigs with
the three branches which spring from the axis. The cceliac
plexus must be left undisturbed, and in following the coronary,
hepatic, and splenic arteries the nerves which accompany them
must be preserved.
Coronary Artery (arteria gastrica sinistra). — This, the
smallest of the three branches of the cceliac axis, proceeds
upwards and to the left, behind the lesser sac of peritoneum,
to the oesophageal opening of the stomach. Here it changes its
direction, enters between the two layers of the gastro-hepatic
omentum, where this is attached to the diaphragm, and runs
from above downwards and to the right along the lesser
curvature of the stomach. Near the pylorus it ends by
anastomosing with the pyloric branch of the hepatic artery.
As the coronary artery ascends on the posterior wall of the abdomen it
raises the posterior layer of the lesser sac in the form of a more or less
distinct fold, which slightly constricts the sac in this situation.
The branches of the coronary artery are : —
1. (Esophageal.
2. Gastric.
The oesophageal arteries (rami cesophagei) spring from the
coronary at the point where it reaches the stomach. They
pass upwards upon the posterior aspect of the gullet, through
the oesophageal opening of the diaphragm, and anastomose
with the oesophageal branches of the thoracic aorta.
The gastric bra?iches take origin from the coronary as it
runs along the lesser curvature of the stomach, and are dis-
tributed to both surfaces of this viscus.
Coronary Vein (vena coronaria ventriculi). — This vein lies
by the side of the artery of the same name. It passes from
right to left along the lesser curvature of the stomach.
Reaching the oesophagus it turns to the right and joins the
portal vein.
460 ABDOMEN
Hepatic Artery (arteria hepatica). — The hepatic artery,
intermediate in size between the coronary and splenic, at first
takes a transverse course to the right along the upper border
of the pancreas. At the pyloric end of the stomach it changes
its direction, and, turning forwards below the foramen of
Winslow, ascends between the two layers of the gastro-hepatic
omentum. Near the transverse fissure of the liver it ends by
dividing into right and left hepatic arteries. The hepatic artery
is accompanied by numerous large nerve twigs derived from
the cceliac plexus, and, as it passes upwards to the liver, it is in
close relationship with the bile duct and the portal vein. The
duct lies upon the right side of the artery, and the vein lies
behind both. (Fig. 165, p. 434, and Fig. 181, p. 479.)
As the hepatic artery runs behind the lesser sac of the peritoneum and
then turns forwards to reach the gastro-hepatic omentum, it (like the
coronary artery) raises a fold of peritoneum which has the appearance of
constricting the lesser sac.
The following are the branches of the hepatic artery : —
1. Pyloric.
r, j j 1 f Superior pancreatico-duodenal.
2. Gastro-duodenal. < -r>.ri. K ■ ■, ■
\ Right gastro-epiploic.
3. Hepa«c{£f ■ \ ^tic.
The pyloric (arteria gastrica dextra) is a small artery which
springs from the hepatic at the pylorus, and then runs from
right to left along the lesser curvature of the stomach between
the two layers of the gastro-hepatic omentum. It ends by
inosculating with the coronary.
The gastro-duodenal (arteria gastro-duodenalis) arises close
to the pyloric artery, and is directed downwards behind the
first part of the duodenum in a groove on the anterior aspect
of the pancreas at the junction between the neck and the
head of that organ. At the lower border of the duodenum it
ends by dividing into the superior pancreatico-duodenal and
the right gastro-epiploic.
The superior pancreatico-duodenal (arteria pancreatico-
duodenalis superior) proceeds downwards on the head of the
pancreas to the interval between it and the duodenum. Here
it turns round the border of the pancreas and on the posterior
aspect of its head forms an arch with the inferior pancreatico-
duodenal branch of the superior mesenteric artery. The
superior pancreatico-duodenal artery dispenses branches to
both the duodenum and the pancreas.
ABDOMINAL CAVITY 461
The right gastro -epiploic (arteria gastro-epiploica dextra) is
directed from right to left, along the greater curvature of the
stomach, and between the two anterior layers of the great
omentum. It gives branches upwards to both surfaces of
the stomach, and downwards to the great omentum, and ends
by anastomosing with the left gastroepiploic, a branch of the
splenic.
The right and left hepatic arteries, the terminal branches
of the hepatic, diverge from each other, and sink into the
liver at the two extremities of the transverse fissure. From
the right hepatic a small branch called the cystic is given to
the gall-bladder. This divides into two twigs, one of which
ramifies in the areolar tissue between the liver and gall-
bladder and the other upon the opposite surface of the gall-
bladder immediately subjacent to its peritoneal covering.
The cystic vein joins the vena portae or its right branch.
Splenic Artery (arteria lienalis). — The splenic artery, the
largest branch of the cceliac axis, takes a wavy or tortuous
course behind the lesser sac of the peritoneum to the left
side, and ends in front of the left suprarenal capsule and
kidney by dividing into five or six branches, which enter the
hilum of the spleen.
To obtain a good view of the splenic artery, it is neces-
sary to throw the stomach upwards towards the ribs. The
vessel will then be seen to run along the upper border of
the pancreas, which somewhat overlaps it. It is accom-
panied by the splenic vein, which, however, lies at a lower
level, and therefore altogether behind the pancrc
The following are the branches of the splenic artery : —
1. Pancreatic.
„ r- » • I Vasa brevia.
2. Gastric. - T u . . , .
\ Left gastroepiploic.
3. Splenic.
The arteriie pancreatica are small twigs which come off
at various points for the supply of the pancreas.
The pancreatica magna which is commonly described as
accompanying the duct from left to right in the substance of the pancreas
is not as a rule present.
The vasa brevia (arterias gastricae breves) are five or
small arteries, of which some arise directly from the splenic,
whilst others take origin from its terminal branches. They
run towards the stomach between the two layers of the
462 ABDOMEN
gastro-splenic omentum, and are distributed to the cardiac
end of this viscus, anastomosing with the coronary and left
gastro-epiploic arteries.
The left gastro-epiploic (arteria gastro-epiploica sinistra) takes
origin from the splenic near the spleen, and is directed from
left to right, along the greater curvature of the stomach, between
the two anterior layers of the great omentum. It gives branches
which ascend to supply both aspects of the stomach, and others
which descend into the great omentum, and it ends by anas-
tomosing with the right gastro-epiploic artery.
The splenic or terminal branches of the splenic artery reach
the spleen by passing between the two layers of the lieno-renal
ligament. The vasa brevia and the left gastro-epiploic artery
take the same route to gain the interval between the two
layers of the gastro-splenic omentum.
From the above description of the branches of the cceliac axis it will be
seen that the stomach is remarkably rich in blood-vessels. Two proceed
from left to right — viz. . the coronary along the lesser curvature, and the
left gastro-epiploic along the greater curvature ; two, both branches of the
hepatic, are directed from right to left — viz., the pyloric, in relation to the
lesser curvature ; and the right gastro-epiploic, in relation to the greater
curvature. The arterial circle is completed on the left by the vasa brevia,
which connect the coronary artery with the left gastro-epiploic.
Splenic Vein (vena lienalis). — This large vein, formed by
the union of the veins which issue from the spleen, runs from
left to right behind the pancreas, and at a lower level than
the artery of the same name. After crossing the aorta and
the root of the superior mesenteric artery, it ends by joining
the superior mesenteric vein to form the vena portae. In its
course between the spleen and the vena portae it receives the
following tributaries: — (i) veins corresponding to the vasa
brevia ; (2) the left gastro-epiploic vein; (3) pancreatic veins :
(4) the inferior mesenteric vein.
Vena Portae. — This is a remarkable vessel. It arises after
the manner of a vein, by gathering, by means of its rootlets,
the blood from the capillaries of the entire abdominal por-
tion of the alimentary canal (with the exception of a part of
the blood from the anal canal), the spleen, pancreas, and gall-
bladder, whilst it ends in the liver after the manner of an
artery, by pouring its blood into the hepatic capillaries. The
blood which flows in the portal vein, therefore, has passed
through two series of capillaries before it is returned to. the
ABDOMINAL CAVITY 463
heart — viz. ( 1 ) the capillaries of the organs from which it
is derived; (2) the hepatic capillaries.
The portal vein is formed between the neck and the head
of the pancreas, by the union of the splenic and superior
mesenteric veins. From this it ascends, with an inclination
to the right, and ends near the right extremity of the trans-
verse fissure of the liver by dividing into a right and left
branch, one for each lobe of this organ. After emerging from
under cover of the neck of the pancreas, it lies first behind
the first part of the duodenum, and then between the two
layers of the gastro-hepatic omentum, close to its right free
margin. In the latter situation it is placed behind the
hepatic artery and the bile duct, and is accompanied by the
hepatic nerves and lymphatics. The vena portse receives the
coronary, pyloric, and cystic veins. The last-named vein,
however, may join its right branch.
The branches of the portal venous system are devoid of
valves. This is a predisposing cause in the production of
haemorrhoids.
Dissection. — The connections of the duodenum should ne
and in cases where the abdominal viscera have not been hardened
by formalin the dissector will find it advantageous in doing this to |
inflate with air both it and the stomach.
Duodenum. — The duodenum, or first part of the small
intestine, is wider and more fixed in its position than either
the jejunum or ileum. It is ten to twelve inches in len_
and extends from the pylorus of the stomach to the left side
of the body of the second lumbar vertebra. Here it bends
forwards on itself in the form of the duodeno-jejunal flexure
and becomes continuous with the jejunum (Fig. 175). The
duodenum describes upon the front of the vertebral column
a U-shaped curve, the concavity of which is directed upwards
and to the left, and within which is placed the head of the
pancreas. For convenience in description it is divided into
a first part, a second part, and a third part.
The first part of the duodenum (pars superior) is two inches
in length, and is contained in the epigastric region. For
about one inch from the pylorus it is enveloped by the same
two layers of peritoneum which invest the stomach, and
consequently enjoys a limited degree of movement ; in its
terminal part it is only covered on its anterior surface by the
peritoneum. Its position and relations are dependent upon
464
ABDOMEN
the desree of distension of the stomach. When that viscus
is empty, and the pylorus, in consequence, lies close to the
mesial plane, the first part of the duodenum passes backwards
and to the right, with a slight inclination downwards in
correspondence with the slope of the visceral surface of the
liver, until it reaches the neck of the gall-bladder. Here it ends
by bending suddenly downwards into the second part. Under
Foramen of Winslow
Hepatic artery
Portal vein
Common bile-duct
Transverse
meso-colon
(divided)
Fig. 175. — Duodenum, Pancreas, and Kidneys. (From the model by His. )
H.F. Hepatic flexure of the colon.
Splenic flexure of the colon.
Mesentery.
Superior mesenteric vessels.
Jejunum.
s.c.
Suprarenal capsule.
H.F
s.
Spleen.
S.F.
R.K.
Right kidney.
M.
L.K.
Left kidney.
S.M
P.
Pancreas.
J-
D.
Duodenum.
these circumstances the first part of the duodenum lies in close
apposition with the lobus quadratus of the liver. When the
stomach, on the other hand, is distended, the pylorus comes
into relation with the lobus quadratus, and the first part of
the duodenum is somewhat shortened, proceeds straight
backwards, and occupies a depression on the under surface
of the right lobe of the liver, behind and to the right of the
ABDOMINAL CAVITY 465
transverse fissure. The relations of the first part of the
duodenum are as follows : above and in front, the under
surface of the liver ; below, the pancreas ; behhid, the common
bile-duct, the gastro-duodenal artery, and the portal vein.
The second part of the duodenum (pars descendens) is
usually about from three to four inches in length, and takes
a downward course from the under surface of the liver.
Placed at its commencement in the epigastric region, it
descends into the umbilical region, lying close to the right
Poupart plane. Reaching the level of the third lumbar
vertebra, it turns across the spine and enters upon the third
stage of its course. The second stage of the duodenum is
immovably fixed in its position. It is covered by peritoneum
on its anterior surface only, and is crossed by the commence-
ment of the transverse colon, which, in this part of its course,
does not as a rule possess a mesentery (Fig. 175). Behind,
it rests upon the vena cava and presents a variable relation
to the renal vessels and the anterior surface of the right kidney
in the neighbourhood of the hilum. To the right, is the
hepatic flexure of the colon ; and to the left, is the head of the
pancreas, which is moulded upon the inner side of this part
of the duodenum.
The common bile-duct and the pancreatic duct open into
the inner and back aspect of the second part of the duodenum
a little below its middle.
The third part of the duodenum (pars ascendens) is some-
what longer than the second part, and may be regarded as
being composed of two portions, viz., an oblique and a
vertical. The oblique portion begins on the right side of the
third lumbar vertebra and extends across the spine from
right to left with a decided inclination upwards. It is
moulded upon the vena cava and aorta which lie behind it,
and it is crossed by the superior mesenteric vessels and the
root of the mesentery. The pancreas is adapted to its upper
aspect. The vertical portion commences on the left side of
the aorta ; here the duodenum changes its direction and
proceeds vertically upwards upon the psoas muscle and left
renal vessels for an inch or more. Having gained the left
side of the body of the second lumbar vertebra, the duodenum
suddenly bends forwards upon itself and forms the duodeno-
jejunal flexure.1 The lower surface of the body of the pancreas
is moulded on the summit of this flexure.
vol. 1 — 30
466 ABDOMEN
At its commencement the third portion of the duodenum
is placed in the umbilical region, but it gradually crosses the sub-
costal plane, and its terminal part is situated in the epigastric
region. The third part of the duodenum is fixed in its position.
It is covered by peritoneum on its anterior surface, and is
crossed obliquely by the root of the mesentery proper.
Suspensory Muscle of the Duodenum and Mesentery-
Proper. (Lockwood.) — The flexura duodeno-jejunalis and
the root of the mesentery are held in position and prevented
from slipping down on the posterior wall of the abdomen by
a band of involuntary muscular fibres, which fixes them to
the diaphragm. This band is called the suspensory muscle
of Treitz. It is attached above to the diaphragm, on the
right side of the oesophageal aperture. From this it proceeds
downwards on the left side of the coeliac axis artery to the
flexura duodeno-jejunalis, into which a large number of its
fibres are inserted. The remaining fibres enter the mesentery
and find attachment to the peritoneum. In the child the
suspensory muscle is well marked and easily isolated, but in
the adult it loses its distinctly muscular character and
becomes more or less blended with neighbouring tissues.
Pancreas. — The pancreas is an elongated gland which
stretches transversely across the posterior wall of the abdomen
behind the stomach. For the most part it is situated in the
epigastric region, a small portion only of its left extremity
being placed in the left hypochondriac region. As in the case
of the other solid organs contained within the abdominal
cavity, its form is greatly modified by the condition of the
hollow viscera in its immediate vicinity, and its true shape
can only be ascertained by preserving it in situ by repeated
injections of some hardening reagent. It may be described
as consisting of a head, a neck, a body, and a tail.
The head of the pancreas is a flattened portion of the
gland which lies in front of the spine and occupies the con-
cavity of the duodenum. It rests upon the inferior vena cava
and to some extent .also upon the aorta, whilst its anterior
surface is crossed by the transverse colon. As a rule its
margins tend to overflow the duodenal boundary : in other
words, its marginal lobules show a tendency to wander over
the anterior surface of the second and third parts of the
duodenum so as to overlap the gut in the vicinity of its con-
cavity. Certain other relations may be noticed in connec-
ABDOMINAL CAVITY 467
tion with the head of the pancreas, viz. : (1) the common
bile-duct passes down behind it in close relation to the
second part of the duodenum; (2) the vena portae is formed
in front of it; and (3) its lower part is prolonged to the left
along the upper border of the third part of the duodenum
(processus uncinatus), and in front of this the superior
mesenteric vessels are carried downwards.
The neck of the pancreas (Symington) is a narrow constricted
portion of gland- substance which springs from the anterior
aspect of the head, nearer its upper than its lower margin.
It constitutes the link of connection between the head and
the body of the pancreas, and as it proceeds to the left it lies
in front of the commencement of the vena portae and of the
termination of the superior mesenteric vein. These vessels
intervene between the neck and the front surface of the head
of the pancreas. The anterior surface of the neck is covered
by that layer of peritoneum which forms the posterior wall
of the lesser sac, and is usually somewhat depressed by the
pyloric end of the stomach, which rests upon it.
The body of the pancreas, where it becomes continuous
with the neck of the organ, lies in front of the superior
mesenteric artery and the aorta. From this it stretches back-
wards, and to the left over the lower part of the left suprarenal
capsule and the front of the left kidney (Fig. 187, p. 490).
It presents a posterior, a superior, and an inferior surface
separated from each other by a superior, an anterior, and a
posterior border. The posterior surface is moulded on the
structures upon which it rests, and the splenic vein runs
towards the portal vein under cover of it. The superior
surface looks upwards and forwards, and is covered by the
layer of peritoneum which forms the posterior wall of the lesser
sac. This surface of the pancreas in the greater part of its
extent supports the postero-inferior aspect of the stomach,
and is consequently hollowed out for its reception. Immedi-
ately adjoining the neck a smooth rounded prominence on
the anterior surface of the pancreas juts upwards and forwards,
above and to the left of the pyloric portion of the lesser curva-
ture of the stomach, and abuts against the gastro-hepatic
omentum. This is called the tuber omentale (His). Above
this prominence and partly under cover of it the cceliac
axis extends forwards from the aorta, and breaks up into its
three branches. The inferior surface of the body of the
1— 30 a
468
ABDOMEN
pancreas looks downwards and rests upon the flexura
duodeno-jejunalis, the coils of the small intestine, and the
transverse colon close to the splenic flexure. It is completely
covered by the peritoneum, which forms the posterior layer of
the transverse meso-colon, and varies greatly in extent : this
variation being due to the varying degrees of intestinal
pressure to which the pancreas is subjected from below.
The gastric pressure exerted on the pancreas from above, and the counter-
pressure which is exerted by the intestine on the inferior surface of the
organ from below, varying as they do in the same individual, according to
the condition of these hollow viscera, determine, in a great measure, the
shape of the body of the pancreas. The body of the pancreas has the
appearance of being wedged in between the two layers of the transverse
meso-colon at its root.
Duodenum
Accessory
pancreatic
duct
Pancreatic duct
Superio mesenteric artery
Superioi mesenteri; vein
Head of pancreas
Branch of
accessory duct
Fig. 176. — Dissection of Pancreas from behind to show its Ducts.
(Birmingham. )
The splenic artery pursues a wavy course along the superior
border of the pancreas, whilst the transverse meso-colon is
attached posteriorly to the pancreas along its anterior border.
The tail of tJie pancreas abuts against the visceral aspect of
the spleen, and usually rests upon a small depression on the
lower and inner part of the gastric concavity of that organ
(Fig. 187, p. 490).
Ducts of the Pancreas. — The ducts of the pancreas are, as
a rule, two in number — a main duct and an accessory duct.
Both run within the gland substance.
The main pancreatic duct or the canal of Wirsung begins at
the tail of the gland by the union of the small ducts issuing
from the lobules in this region, and it proceeds transversely
towards the right. It gains considerably in size as it traverses
ABDOMINAL CAVITY 469
the organ from its being joined by the small ducts which
come from the various groups of lobules. Reaching the neck
of the gland, it bends downwards in the substance of the head.
By dividing the gland horizontally, little difficulty will be
experienced in discovering the main duct. The extreme
whiteness of its walls is a help to the student in this dissection.
Close to the duodenum the pancreatic duct comes in contact
with the common bile-duct, and both pierce in company the
coats of the descending part of the duodenum upon its posterior
and inner aspect, and open into the gut by a common orifice.
The accessory duct is small, and arises in the lower part
of the head of the gland. It usually has an independent
opening into the duodenum, immediately above the opening
of the main duct.
Hepatic Ducts (Fig. 184). — Issuing from the bottom of
the transverse fissure of the liver, the student will notice two
ducts, called respectively the right and left hepatic ducts.
These unite within the transverse fissure to form the hepatic
duct, which in turn is shortly joined by the cystic duct
of the gall-bladder. The junction of the cystic and hepatic
ducts gives rise to the common bile-duct, or the ductus communis
choledochus, and this descends between the two layers of the
gastro-hepatic omentum to the right of the hepatic artery and
in front of the vena portse. Passing behind the duodenum
and the head of the pancreas, it ends by opening, as we have
already seen, into the second part of the duodenum.
Dissection. — The attention of the student should now be directed to the
ending of the vagi nerves within the abdominal cavity, and also to the
great epigastric or solar plexus of the sympathetic. For the proper display
of these it is necessary to divide the gastro-duodenal artery, the common
bile-duct, and the portal vein at the level of the upper border of the first
part of the duodenum, and then, having allowed the air to escape from the
stomach and duodenum, to throw both, along with the pancreas, over to
the left side of the body. The dissection of the solar plexus is a very
tedious one, because mingled with the nerves, which are soft and easily
broken, are several lymphatic glands and a quantity of tough areolar tissue.
Pneumogastric or Vagi Nerves. — These enter the abdomen
through the oesophageal opening of the diaphragm. The left
vagus will be found lying upon the anterior aspect of the
gullet. Trace it downwards and notice that it breaks up
into branches, the greater number of which spread out upon
the antero-superior wall of the stomach ; a few, however, run
to the right, along the lesser curvature, and establish communi-
470 ABDOMEN
cations with the coronary plexus, whilst others ascend between
the two layers of the gastro-hepatic omentum to reinforce
the hepatic plexus. The right vagus lies upon the posterior
aspect of the gullet, and at once breaks up into numerous
branches which ramify upon the postero-inferior wall of the
stomach ; it also sends twigs to the cceliac plexus, to the splenic
plexus, and to the left re?ial plexus.
Solar or Epigastric Plexus. — In connection with the
sympathetic system three large plexuses are formed in front
of the vertebral column — viz., the cardiac plexus in the thorax,
the solar plexus in the upper part of the abdomen proper,
and the hypogastric plexus in the lower part of the abdomen
proper. These receive the name of the prevertebral plexuses.
The solar plexus is by far the largest of the three. It is
situated behind the stomach, in front of the aorta and the
pillars of the diaphragm. Upon each side it extends as far
as the suprarenal capsule, whilst inferiorly it passes downwards
behind the pancreas. On each side of the body, where
it lies upon the crus of the diaphragm, a large ganglionic
mass, called the semilunar ganglion, is developed in its midst.
Distinctive terms are applied to different parts of the
plexus. The portion which connects the semilunar ganglia
and surrounds the cceliac axis is called the coeliac plexus.
To the outer side of each ganglion the plexus ends in
numerous branches for the suprarenal body and kidney, and
these are classified under the terms of suprarenal and renal
plexuses. Inferiorly, the plexus has already been seen to send
downwards large offshoots which accompany the aorta and
the superior mesenteric artery ; these are the aortic and
superior ??iesenteric plexuses. Lastly, a small offset from the
upper part of each semilunar ganglion is termed the
diaphragmatic plexus.
Semilunar Ganglia (ganglia coeliaca). — These are so large
that they are not infrequently mistaken by students for
lymphatic glands. The ganglion of the right side is placed
under cover of the vena cava inferior, and both lie in close
relation to the cceliac axis. When defined, they will be
observed to be of a very irregular shape, and to show little
of the outline from which their name is derived. The upper
extremity of each ganglion is joined by the great splanchnic
nerve, whilst into its lower part, which is often more or less
detached, may be traced the small or second splanchnic nerve.
ABDOMINAL CAVITY 471
Coeliac Plexus (plexus coeliacus). — This plexus of nerves
connects the two semilunar ganglia with each other, and
surrounds the cceliac axis so closely that it almost completely
hides its trunk from view. It is reinforced by twigs from the
right vagus. Three secondary plexuses — viz., the coronary, the
hepatic, and the splenic — take origin from the cceliac plexus.
The coronary plexus (plexus gastricus superior) accompanies
the artery of the same name along the lesser curvature of the
stomach, and distributes twigs to both aspects of the viscus.
The hepatic plexus (plexus hepaticus) follows the hepatic
artery, the vena portae, and the bile-duct to the transverse
fissure of the liver. It is joined by twigs from the left
pneumogastric, and it gives origin to the pyloric, right gastro-
epiploic, superior pancreaticoduodenal, and cystic plexuses, which
accompany the arteries of the same names.
The splenic plexus (plexus lienalis) is prolonged along the
splenic artery to the spleen. It is joined by twigs from the
right pneumogastric, and gives off branches to the pancreas
and to the fundus of the stomach, and also the left gastro-
epiploic plexus.
Renal Plexus (plexus renalis). — This consists of numerous
nerves which spring chiefly from the lower and outer part of
the semilunar ganglion. Some will be found, however, coming
from the cceliac, and others from the aortic plexus. The
smallest or third splanchnic nerve, when it is present, joins this
plexus. Thus constituted, the filaments of the renal plexus
run with the renal artery to the hilum of the kidney, and are
distributed within the gland substance. Several twigs are
likewise given to the spermatic plexus. A few scattered
ganglia are usually found in connection with the renal plexus.
Suprarenal Plexus (plexus suprarenalis). — The dissector
will be struck with the large number of nerves which supply
the suprarenal body. The nerves composing the plexus are
chiefly derived from the semilunar ganglion, but many come
from the cceliac plexus. Below, it is directly continuous with
the renal plexus, and above, it is connected with the dia-
phragmatic plexus. The smallest splanchnic nerve usually
contributes a branch to this plexus, and the point at which
it joins is marked by a small ganglion.
Diaphragmatic Plexus (plexus phrenicus). — The filaments
composing this plexus take origin from the upper part of the
semilunar ganglion, and are distributed with the phrenic artery
472 ABDOMEN
to the under surface of the diaphragm, but they do not follow
rigorously the branches of this vessel. At first they lie
subjacent to the peritoneum, but soon they penetrate between
the fleshy fasciculi and establish communications with the
phrenic nerve. On the right side a small ganglion is formed
on the under surface of the diaphragm at the point of
junction between this plexus and the phrenic. In addition
to its diaphragmatic branches, it contributes filaments to the
suprarenal plexus, and, on the right side, to the hepatic plexus.
Dissection. — Apply two ligatures to the oesophagus, where it enters the
stomach, and divide it between them. The stomach, duodenum, pancreas,
and spleen may now be removed by dividing the vessels, nerves, and
peritoneal folds which still hold them in position.
Spleen. — Several important points in connection with the
internal structure of this organ may be recognised in the
dissecting-room. It is enveloped by two coats — (i) serous;
(2) fibro-elastic. The perito?ieal investment adheres so closely
to the subjacent fibrous coat that it can only be removed
with difficulty. With regard to the fibro-elastic tunic (tunica
propria), it should be noted that processes proceed from
its deep surface and dip into the substance of the organ.
These are the trabecules, and they constitute the supporting
framework of the gland-puip. On account of this arrange-
ment, it will be found utterly impossible to strip off the
fibrous coat of the spleen without at the same time lacerating
its surface. Make a section through the organ, and carry a
portion of it to the tap. By squeezing it and allowing the
water to run freely over it, a view of the trabecular framework
may be obtained.
Dissection. — Detach the pancreas from the duodenum, but leave a
portion of the duct in connection with the gut. Next clean out the stomach
and duodenum by allowing water to run freely through them. The
duodenum may now be separated from the stomach by cutting through its
walls about an inch beyond the duodeno-pyloric constriction. If the
stomach is relaxed and flaccid the dissection of its walls may be facilitated
by inflating it with air.
Coats of the Stomach. — The coats of the stomach should
now be examined. They are five in number, viz. : —
1. Peritoneal, or serous.
2. Subserous.
3. Muscular.
4. Submucous.
5. Mucous.
The serous coat, derived from the peritoneal membrane,
ABDOMINAL CAVITY
473
can be best stripped off with the fingers. The subserous coat
is composed of a little areolar tissue which intervenes between
the muscular and serous strata. The branches of the two
pneumogastric nerves can now be followed, as they spread out
upon both surfaces of the stomach.
The muscular coat consists of involuntary or unstriped
muscular fibres, and these are disposed in three incomplete
layers — each layer being distinguished by the direction of its
fibres. The external layer (stratum longitudinale) is composed
of fibres which run for the
most part in the longitudinal
direction. The longitudinal
fibres of the oesophagus in
reaching the cardiac orifice
radiate over the stomach in
all directions, but more
particularly along the lesser
curvature, and they disappear
(with the exception, perhaps,
of some on the lesser curva-
ture) before they reach the
pyloric part of the organ.
On the body of the stomach
a new and independent set
of longitudinal fibres take
origin, and these gradually
form a continuous layer
which gains in strength and
thickness as it sweeps on-
wards towards the pylorus.
The middle layer (stratum
circulare) is composed of circular fibres, which are continuous
with the more superficial circular fibres at the lower end of
the oesophagus. They do not form a continuous coating for
the stomach (Birmingham). Beginning as a series of loops
immediately to the right of the oesophageal opening, they
gradually increase in length as the layer is followed towards
the pylorus, and soon they completely encircle the organ
and form a continuous stratum. No fibres of this layer
encircle the fundus. At the pyloric canal the circular fibres
undergo a marked increase in numbers, and at the duodeno-
pyloric constriction they are aggregated together into a thick
Fig. 177. — Dissection of the three layers
of Muscular Fibres in the Wall of the
Stomach.
474 ABDOMEN
circular ring, called the pyloric sphinderic ring. The internal
layer (fibrae obliquae) consists of oblique fibres, which give a
partial covering to the stomach. They are continuous with
the deeper circular fibres of the gullet, and are best seen
immediately to the left of the cardiac opening. From this
they spread out in a series of loops which embrace the
oesophageal opening and proceed obliquely to the right over
both surfaces of the viscus. As these muscular loops
are traced towards the fundus, they are found to gradually
assume the form of a complete coating of circular fibres for
this part of the organ (Birmingham).
The submucous coat is composed of lax areolar tissue.
It intervenes between the muscular and mucous tunics,
binding them loosely to each other and in such a manner
that the mucous membrane can glide freely upon the deep
surface of the muscular coat.
The mucous coat must be studied from the inside of the
stomach. Open up the viscus by running the scissors along
the lesser curvature as far as the pyloric canal. The gastric
mucous membrane will now be seen to be thick, soft, and
pulpy. In the dissecting-room the student cannot obtain a
proper idea of its natural colour. In infancy it is rosy red,
but as life advances it gradually becomes paler, and in old
age it presents a brownish hue from the presence of pigment.
When the mucous membrane is cleansed and examined with
a pocket-lens, its surface is observed to present a pitted
appearance. Innumerable polygonal depressions are brought
into view, and these are observed to be larger and better
marked near the pylorus than in the vicinity of the fundus.
At the bottom of these pits are the mouths of the minute
tubular glands of the gastric mucous membrane.
The mucous membrane has little elasticity, and con-
sequently when the stomach contracts and becomes empty
the membrane is thrown into projecting folds or rugae which
for the most part run in the longitudinal direction and
occupy the cavity of the organ. As the stomach expands
these folds open out and finally disappear when complete
distension is attained.
Pyloric Orifice and Pyloric Canal. — The extremity of the
pyloric canal protrudes into the commencement of the
duodenum so that, when viewed from the duodenal side, it
presents the appearance of a smooth rounded knob with a
ABDOMINAL CAVITY
475
Small puckered orifice, the pyloric opening, in its centre and
surrounded by a shallow furrow or fornix. The resemblance
which it presents to the os uteri externum is very striking.
When the stomach has been properly hardened in situ the
pyloric orifice is almost invariably found tightly closed. It
is only on rare occasions that the opening is patent. In
such cases it is circular, and surrounded by a ring-like ledge
which has been called the pyloric valve ; but it is doubtful if
this is a natural condition. During life the pyloric opening
may be regarded as being always rigidly closed, except during
digestion, when it opens intermittently and at irregular
intervals to allow material to be squirted from the stomach
into the duodenum.
The muscular coat of the pyloric canal is modified to suit
Orifice of pyloric canal of stomach
Termination of pyloric canal
protruding into duodenum
Duodenum
Pyloric part of stomach
-*<P-
Fig. 178. — Small portion of the Pyloric part of the Stomach with part
of Duodenum attached.
the requirements of this section of the stomach. It is provided
with a powerful sphincteric apparatus. Both the circular and
longitudinal muscular fibres are .present in greater mass than
in any other part of the organ. The circular fibres are
disposed in the form of a thick sphincteric muscular cylinder
which surrounds the entire length of the pyloric canal. At
the duodeno-pyloric constriction the margin of this cylinder
becomes increased in thickness, forming thereby the massive
muscular ring which encircles the pyloric orifice and con-
stitutes the pyloric sphincteric ring. The knob -like appear-
ance presented by the extremity of the pyloric canal when
viewed from the interior of the duodenum is produced by the
presence, beneath the mucous membrane, of this muscular
ring. The sphincteric cylinder which surrounds the pyloric
canal varies much in its thickness in accordance with different
•degrees of contraction of the canal.
476
ABDOMEN
The longitudinal muscle-fibres likewise form a thick layer
on the superficial aspect of the sphincteric cylinder and ring.
They are uniformly disposed around the pyloric canal, but
comparatively few of these fibres pass superficially over the
duodeno-pyloric constriction to become continuous with the
corresponding fibres of the muscular coat of the duodenum.
As they approach the duodenum the deeper longitudinal
fibres of the pyloric canal leave the surface and penetrate the
substance of the pyloric sphincteric ring. There can be little
doubt that by this arrangement an effective apparatus,
Incisura anguk
Sphincteric cylinder
Duodeno-pyloric constriction
Sphincteric ring
Orifice of pyloric canal
Interior of duodenum \,__
Sphincteric ring
Duodeno-pyloric constriction
Sphincteric cylinder
Pyloric vestibule
Fig. 179. — Pyloric Canal and Pyloric Vestibule of the Stomach opened up
by section in. the plane of the two curvatures.
antagonistic to the pyloric sphincteric ring, is provided by
means of which, when the sphincter relaxes, the pyloric
orifice may be dilated. There is thus a constrictor and a
dilator of the pylorus.
In suitable specimens this arrangement of the muscle
fibres may be seen by the naked eye when a longitudinal
section is made through the pyloric canal in the plane of the
two curvatures of the stomach.
Dissection. — The duodenum which has previously been detached from
the stomach may now be opened up by dividing its wall with the scissors
along the convexity of its curvature.
Coats of the Duodenum. — In connection with the duo-
ABDOMINAL CAVITY
477
denum, note that the valvulae conniventes begin about one
or two inches beyond the pylorus, about the commencement
of its second part ; that the mucous membrane is covered by
villi ; and that usually no Peyer's patches are to be seen.
Pass a probe along the bile-duct, and another along the pan-
creatic duct. These ducts will then be observed to pierce the
coats of the duodenum, side by side, very obliquely, and to
open by a common orifice, which is placed on the summit of a
papillary projection of mucous membrane, termed the bile
papilla (papilla duodeni). From the under surface of this
projection a ridge of mucous membrane (frenulum) passes
downwards, and gives a downward inclination to the biliary
opening on the sum-
mit of the papilla.
Hood-like val-
vula connivens
Bile-papilla
Common opening
of bile and pan-
creatic ducts
~ Frenulum
Fig. 180. — The Bile- Papilla in the interior
of the Duodenum. (Birmingham.)
The duodenum should
now be pinned down,
with its mucous surface
undermost, to the bottom
of a cork-lined tray filled
with water. Its coats
may then be dissected.
They are in all respects
similar to those already
examined in connection
with the jejunum (p. 45 1 ).
If the dissection is carried
on until the deep surface
of the submucous coat
is exposed by the removal
of the entire muscular
coat, a view of Brunner's
glands may be obtained.
They appear as whitish specks, about the size of hemp-seed, in the sub-
mucous tissue. They are most numerous close to the pylorus, and gradually
disappear about two inches beyond this.
Removal of the Liver. — The student has already examined the position
and connections of the liver (p. 409). It should now be removed from the
abdominal cavity, in order that its form and the manner in which the
vessels are distributed in its substance may be studied. Begin by dividing
the ligamentum teres and the falciform ligament. Then drawing it down-
wards, cut through the lateral ligament on each side and the upper layer
of the coronary ligament. Having done this, the bare area on its posterior
border can be separated from the diaphragm with the handle of the knife.
Observe that this portion of the liver is merely connected to the diaphragm
by areolar tissue. Soon the vena cava inferior will be exposed, emerging
from the posterior surface of the liver, and then piercing the central tendon
of the diaphragm. This must be severed. On dividing the lower layer of
the coronary ligament, the liver will be free from all the surrounding parts,
except the vena cava, at the point where it first comes in contact with the
478 ABDOMEN
organ. The vena cava must, therefore, be cut a second time, and thus a
portion of the vessel is taken away with the gland.
Liver (hepar). — In the adult male the weight of the liver
will be found to vary from 50 to 60 ounces, and in the
adult female from 40 to 50 ounces. It represents about
1/3 6th of the weight of the whole body. In infancy and
childhood it is relatively larger than in later life.
In form the liver has been seen to resemble, while in situ
and supported by surrounding viscera, a right-angled triangular
prism (Symington), and to present a basal or right lateral
surface, a superior surface, an anterior surface, a posterior
surface, and an inferior or visceral surface. Unless means
have been taken to harden it in position before the abdomen
has been opened, the liver, when placed on the table before
the dissector, in a great measure loses this shape. It becomes
flattened, the distinction between the anterior and superior
surfaces is lost, and the inferior and posterior surfaces also
tend to run into each other. It is necessary, therefore, to
correct the impressions which are received from such a dis-
figured organ by reference to a specimen which has been
specially prepared.
Longitudinal Fissure. — The inferior and posterior surfaces
of the liver alone remain to be studied. Upon these the
demarcation of the organ into a right and a left lobe is
effected by the longitudinal fissure. This furrow pursues a
course which corresponds with the line of attachment of the
falciform ligament on the superior and anterior surfaces. The
portion of the longitudinal fissure, which traverses the inferior
surface, extends from the anterior border, where it begins in
a notch, in a straight direction backwards to the left extremity
of the transverse fissure. It lodges the obliterated umbilical
vein or ligamentum teres, and is in consequence termed the
umbilical fissure. Sometimes it is more or less completely
bridged over by liver substance, so that a portion, or perhaps
the whole of it, is converted into a tunnel or canal. In these
cases, the overlying piece of liver substance constitutes a link
between the right and left lobes, and receives the name of
pons hepatis. The continuation of the longitudinal fissure on
the posterior surface begins at the left extremity of the trans-
verse fissure, and takes a vertical course upwards. It lodges
the slender fibrous cord which represents in the adult the
ductus venosus of the foetus. It is consequently called the
ABDOMINAL CAVITY
479
fissure of the ductus venosus. The fibrous cord, which lies
within it, is attached below to the left branch of the portal
vein, and above to the upper end of the inferior vena cava.
Inferior or Visceral Surface of the Liver. — Having recog-
nised the boundary line between the two main lobes of the
liver, the dissector should examine carefully the inferior and
posterior surfaces. The inferior visceral surface, when the
liver was in situ, has been seen to be very oblique, and to
look as much to the left as in a downward direction. It is
to some extent also slightly hollowed out, or concave, and it
ROUNDJlLIG?:
Impression for suprarenal capsule
Inferior vena cava
Common bile-duct
Gastro-hepatic omentum
Hepatic artery
Portal vein
Fig. 181. — The Inferior or Visceral Surface of the Liver.
bears upon itself the impress of the various organs with which
it is in contact. Thus the left lobe presents a concavity of
greater or less extent according to the degree of distension of
the stomach upon which it is moulded (impressio gastrica).
It also exhibits, in the neighbourhood of the longitudinal
fissure, a smooth rounded boss or eminence, termed by His
the tuber omentale. This prominence lies above and to the
right of the lesser curvature of the stomach, and is consequently
in contact with the anterior surface of the gastro-hepatic
omentum (Fig. 181).
The inferior surface of the right lobe of the liver is much
480
ABDOMEN
more extensive than that of the left lobe. Upon it we
recognise the transverse fissure and the fossa for the gall-
bladder (Fig. 181).
The transverse fissure (porta hepatis) is the deep depression
or hilum within which the portal vein and the hepatic artery
and nerves enter the liver, and the lymphatics and bile-ducts
leave the liver. It is sometimes spoken of as the "porta"
or " gate " of the gland. Beginning at the posterior extremity
of the umbilical fissure, it extends transversely to the right
for a distance of two inches, and then ends abruptly.
Right lateral ligament
Left latera
ligament
(Esophageal
groove
Gastro-hepatic
omentum
Tuher omentale
Caudate lobe
Impression for suprarenal capsule
Gall-bladder
Colic impression
FlG. 182. — Posterior Surface of the Liver.
The fossa for the gall-bladder (fossa vesicae felleae), parallel
to the umbilical fissure, extends upon the under surface of
the right lobe from the anterior sharp border to a point close
to the right extremity of the transverse fissure. In this the
gall-bladder is lodged, and it varies in depth and extent with
the condition of that sac.
By means of the transverse fissure and the fossa for the
gall-bladder, the inferior surface of the right lobe of the
liver is subdivided into three unequal portions. Thes'e are —
(1) the lobus quadratus ; (2) the lobus caudatus ; and (3) an
extensive area which lies to the right of these, and forms the
greater part of the under surface of the right lobe.
AliOOMIXAL CAVITY
481
The lobus quadratus is an oblong quadrilateral area, cut off
on all sides from the adjoining liver surface. It is bounded
behind by the transverse fissure, in front by the anterior sharp
margin of the organ, on the left by the umbilical fissure,
and on the right by the gall-bladder and its fossa. The surface
of the lobus quadratus is usually somewhat depressed, and
when the liver is in position and the stomach empty, it is in
contact with the first portion of the duodenum. When the
< Esophagus
Left lateral ligament of liver
Inferior vena cava
Coronary ligament
Tuber omentale of liver
Spigelian lobe
Tylorus Ureter
FlG. 183. — Liver. Right Kidney, Spleen, and Stomach, as seen from behind.
Drawing taken from a model prepared by the reconstruction method.
stomach is full the pylorus as well as the commencement of
the duodenum are in apposition with it.
The lobus caudatus is a narrow ridge of liver substance
which lies behind the transverse fissure and connects the under
part of the lobus Spigelii with the inferior surface of the right
lobe of the liver. It is placed immediately above the foramen
of Winslow, of which it forms the upper boundary, and inter-
venes between the portal vein, which lies in front of it, and
the inferior vena cava, which is placed behind it.
The greater extent of the inferior surface of the right lobe
of the liver lies to the right of the gall - bladder and the
lobus caudatus. It presents three concave impressions or
vol. 1 — 31
482 ABDOMEN
hollows, viz., an anterior, a posterior, and a small internal
impression. The anterior impression is called the impressio
co/ica, because it corresponds to the summit of the hepatic
flexure of the colon. It is shallow, and looks almost directly
downwards. The posterior impression, the impressio rena/is, is
moulded upon a variable extent of the anterior surface of
the right kidney. It is much deeper than the colic impression,
and it looks more backwards than downwards. When the
hollow viscera in the vicinity are empty, and the abdominal
wall is in consequence retracted, this hollow becomes so
deep that the kidney might almost be said to be sunk into
the liver substance. The small internal impression, the
impressio duodenalis, lies immediately to the inner side of the
renal fossa. It is produced by contact with the duodenum.
Posterior Surface of the Liver (Figs. 182 and 183). — This
is moulded upon the front of the vertebral column, from which
it is separated by the diaphragm and the lower part of the
descending thoracic aorta. It presents, therefore, a deep
hollow corresponding to the bodies of the vertebrae and the
structures in front of these. Immediately to the left of the
fissure of the ductus venosus there is a smooth notch or
groove (impressio oesophagea) which leads downwards into
the gastric fossa on the under surface of the left lobe. This
groove lodges the oesophagus. Beyond the oesophageal groove
the posterior surface of the left lobe merges with the sharp
margin of the organ.
It has been pointed out that the oesophagus is separated from the bottom
of the oesophageal groove in the liver by the prominent anterior margin of
the oesophageal opening of the diaphragm, which in the first instance then
must be regarded as being responsible for this depression (Birmingham).
On the posterior surface of the right lobe may be recog-
nised— (1) the lobus Spigelii ; (2) the fossa for the inferior
vena cava ; and (3) an extensive bare area uncovered by
peritoneum.
The lobus Spigelii is the portion of liver substance which
lies between the fissure of the ductus venosus and the
inferior vena cava. Its lower end appears on the under
surface of the liver immediately behind the transverse fissure,
and runs into the lobus caudatus (Fig. 181). The Spigelian
lobe forms the bottom of the vertebral hollow, and is
separated from the bodies of the tenth and eleventh dorsal
ABDOMINAL CAVITY
483
vertebrae by the diaphragm and the lower part of the descend-
ing thoracic aorta.
The fossa for the inferior vena cava (fossa venae cavae) is a
deep groove placed on the right side of the Spigelian lobe.
It ascends almost perpendicularly, and sometimes it is con-
verted into a tunnel by a bridge of liver substance which
passes over the vein from the one side to the other.
The bare area of the posterior surface of the liver is
triangular in form, and lies to the right of the vena cava.
It forms the greater part of the posterior surface of the right
lobe, and is bounded above and below by the lines of
reflection of the coronary ligament. For the most part it is
convex, and connected with the diaphragm by loose areolar
tissue, and some minute veins which unite the portal vessels
of the liver with the systemic vessels
of the diaphragm ; but close to the
lower end of the fissure for the vena
cava there is a well-marked de-
pression (impressio suprarenalis)
which lodges the right suprarenal
capsule.
Gail-Bladder and Bile-Ducts. —
The gall-bladder is a pyriform
membranous bag placed in a de-
pression on the under surface of the
right lobe of the liver. Its form and
position can be seen to best ad-
vantage by inflating it with air
through the bile-duct. It lies some-
what obliquely, its great end or fundus, free and covered
by peritoneum, being directed downwards, forwards, and to
the right, so as to project slightly beyond the anterior
border of the liver, whilst its narrow extremity or
ends near the right end of the transverse fissure, by
making a double bend like the letter S; and then becoming
continuous with the cystic duct. The upper surface is in
contact with the liver, to which it is connected by areolar
tissue. The under surface is clothed by peritoneum, and is
in relation in front to the transverse colon, and behind to the
first part of the duodenum.
The cystic duct (ductus cysticus) has already been observed
to proceed downwards and to the left to join the hepatic duct,
1—31 a
CYST. DUCT.
Fig. 184. — Diagram of the
Cystic and Hepatic Ducts.
(From Gegenbaur, modified. )
484 ABDOMEN
and thereby form the common bile-duct. The right and
left hepatic ducts issue from the extremities of the transverse
fissure, and unite to form the hepatic duct. To see these
points, it will be necessary to open up the transverse fissure of
the liver and remove a sheath of areolar tissue termed
Glisson's capsule, which surrounds the hepatic ducts and
vessels.
If the dissector now investigates the composition of the
wall of the gall-bladder, he will find that, in addition to its
partial serous covering, it has — (i) a strong coat composed
of muscular and white fibrous tissue, and (2) an internal
mucous coat. The first can be seen by stripping off the
peritoneum, and the second is best displayed by laying open
the gall-bladder with a pair of scissors. The mucous mem-
brane will then be seen to be elevated into ridges which join
with each other so as to form an alveolar arrangement — the
meshes or depressions having a polygonal form. The cystic
duct should also be laid open, when the mucous membrane
in this will be observed to be raised into oblique crescentic
folds, which, when viewed collectively, have a spiral ap-
pearance.
Dissection. — The umbilical fissure, the fissure for the ductus venosus,
and the transverse fissure of the liver should now be opened up, and the
structures contained within them dissected out.
Vessels of the Liver. — Blood enters the liver — (1) by the
hepatic artery, (2) by the large portal vein ; whilst it is led away
from the liver by the hepatic veins.
The hepatic artery is a branch of the cceliac axis, and
carries arterial blood for the nourishment of the liver sub-
stance. It divides into two branches which enter the liver
at the extremities of the transverse fissure.
The portal vein carries venous blood, which it has gathered
from the entire length of the abdominal portion of the ali-
mentary canal (with the exception of the lower end of the
rectum), from the spleen, pancreas, and gall-bladder. It
reaches the under surface of the liver at the right extremity
of the transverse fissure. Here it divides into its two terminal
branches. The right branch is a short wide vessel, which
immediately sinks into the liver ; the left branch, much longer
and considerably smaller, extends to the left along the bottom
of the transverse fissure, and at the left extremity of this
ABDOMINAL CAVITY 485
furrow it enters the liver substance. Near this point the coats
of the left branch of the portal vein are joined in front by the
obliterated umbilical vein, whilst behind it has also attached
to it the obliterated ductus venosus. The terminal part of
the portal vein, just before it divides, is slightly expanded,
forming the sinus of the portal vei?i.
Note the relative position of the vein, artery, and duct at
the transverse fissure. The duct is placed in front, the vein
behind, whilst the artery is intermediate in position. They
and their branches are all enveloped in a common fibrous
sheath called Glisson's capsule. Trace them into the liver
substance for a short distance. The portal vein branches like
an artery, and wherever it divides, there also will the hepatic
artery and hepatic duct be found to divide. The branches of
these three structures, therefore, traverse the liver substance
in company, and Glisson's capsule is prolonged into the liver
with them, and follows them in their ramifications. The
student is now in a position to understand the meaning of
the term " portal canal" It is employed to denote a channel
in the liver substance lined by a prolongation of Glisson's
capsule, and holding in its interior a branch of the portal
vein, a branch of the hepatic artery, and a branch of the
hepatic duct.
The hepatic veins which lead the blood out of the liver
have an arrangement altogether different from the vessels
which enter at the transverse fissure. They converge towards
the fossa for the vena cava on the posterior surface of the
organ, and cannot be said to have any course outside the
liver, as they open directly into the vena cava inferior. The
vena cava should be slit open, when the wide gaping mouths
of the terminal hepatic veins will be displayed. Trace these
veins for a short distance into the substance of the gland.
They are remarkable for the tenuity of their walls, and also
for the very small quantity of areolar tissue which separates
them from the hepatic substance ; indeed, this is so scarce
that it is hardly appreciable to the naked eye. In the case
of the smaller veins it is altogether absent, and the hepatic
lobules rest directly upon their walls.
A section should now be made through the liver substance
and the cut surface examined. The portal veins can be readily
distinguished from the hepatic veins. The following are the
points of difference : —
i-3l &
486 ABDOMEN
Portal Veins. , Hepatic Veins.
1. Are always accompanied by a
branch of duct and a branch of
hepatic artery.
2. Mouths usually collapsed.
3. Walls thicker.
4. Walls separated from the liver
substance by Glisson's cap-
sule.
1. Are solitary and not accom-
panied by any other vessel.
2. Mouths usually open and gaping.
3. Walls exceedingly thin.
4. Walls apparently in direct
apposition with the liver
substance.
Structure of the Liver. — Very little of the structure of
the liver can be learned in the dissecting-room. It is com-
pletely enveloped by a fibro-areolar coat. This is thick where
the peritoneum is absent ; but very thin where that membrane
is spread over the gland. The liver substance presents a
mottled appearance, and when torn or ruptured the surface
exhibits a granular aspect. The minute particles which give
rise to this appearance are the hepatic lobules. In the
human liver these are not completely separated from each
other. Each lobule may be regarded as a miniature liver ;
they are all built up of the same constituents, but these can
only be made out by the aid of the microscope.
Kidneys. — The kidneys are situated behind the peritoneum,
against the posterior wall of the abdomen — one on either side
of the vertebral column. They are enveloped by a capsule of
loose areolar tissue, the meshes of which are at certain points
loaded with soft pliable fat. Clear this away, and be careful
not to remove at the same time the suprarenal body, which lies
upon the upper end of each kidney.
The kidney is placed opposite the bodies of the last dorsal
and the upper three lumbar vertebrae. It extends from the
upper border of the last dorsal vertebra to the middle of the
body of the third lumbar vertebra, and it lies obliquely — its
upper end being somewhat nearer the mesial plane than its
lower end. The kidneys lie for the most part in the hypo-
chondriac and epigastric regions. As a rule the left kidney
is entirely confined to these districts ; but the right kidney,
which as a rule occupies a slightly lower level, crosses the sub-
costal plane so that a small portion of its inferior extremity
comes to lie in the right lumbar and the adjoining part of the
umbilical region. This difference on the two sides is probably
due to the great bulk of the right lobe of the liver. The
twelfth rib lies behind both kidneys. The right kidney does
not, as a rule, extend beyond the upper border of this rib ;
ABDOMINAL CAVITY 4S7
the left kidney may reach the lower border of the eleventh
rib. The lower end of each organ is separated by a short
interval, of varying extent, from the crest of the ilium.
The average length of the kidney is four inches ; its
breadth two and a half inches ; and its average weight four
and a half ounces in the male, but somewhat less in the
female. It is a solid organ, very pliable, and of a brownish-
red colour. The left kidney is, as a rule, slightly longer
and narrower than the right kidney.
Form of the Kidney. — This is so characteristic that the
term "reniform," or " kidney-shaped," has become common
in descriptive language. The anterior surface looks outwards
and forwards, and presents impressions corresponding to the
viscera in contact with it : whilst the posterior surface is directed
inwards and backwards, and is moulded accurately upon the
parts which support it. The extremities are round, but the
superior end is usually thicker and more massive than the
inferior. The external border, smooth and convex, is directed
backwards and outwards ; whilst the internal border is concave,
and looks inwards and forwards. The true form of the
kidneys can only be seen in cases where they have been
carefully hardened in situ.
The kidneys present many changes in form, according to
the amount and the kind of pressure which is exerted upon
them by contiguous viscera. In most cases, however, and
on both sides there is on the anterior surface of the organ
a point of maximum convexity — a place where the kidney
substance is raised in the form of a marked prominence or
bulging. Above and below this eminence the anterior surface
falls away towards each extremity, in the form of an inclined
or sloping plane of greater or less obliquity. These impressed
districts indicate pressure exercised on the anterior surface
of the kidney in two directions, and the intervening eminence
is the result of this pressure and counterpressure. This
characteristic is more constant and better marked in the case
of the left kidney.
Upon the upper inclined plane of the anterior surface of the left kidney
are placed the left suprarenal capsule, the stomach, the spleen, and the
pancreas. These exercise a downward and backward pressure, chiefly
through changes in the condition of the stomach. Upon the inferior
inclined plane of the left kidney the counterpressure is produced by the
intestinal canal, which, as a rule, presses upwards and backwards.
Resting upon the upper inclined plane of the right kidney is the liver,
1—31 c
488
ABDOMEN
whilst in contact with the lower inclined area is the colon. The colon
presses on the kidney in an upward and backward direction. To this
pressure the liver offers a passive resistance, except perhaps in the case
of the slight influence which it conveys in a downward direction from the
diaphragm, and in a backward direction from the anterior abdominal wall.
This pressure and counterpressure, which produce so marked a con-
formation of the anterior surface of the two kidneys, must also exercise
an important influence in maintaining the organ in its place, and securing
it in that part of the abdominal cavity in which it lies. Still it is doubtful
if these influences have so potent an effect on the right as on the left
side. The right kidney is embedded to a greater or less extent _ in the
substance of the liver, and this no doubt exerts an influence in fixing the
organ in position.
Ligaments fixing the kidney to the abdominal wall are described, and
Pancreas
Common bile-duct
Pancreatic duct
Aorta
Duodenum
Vena cava
Cauda equina
Right kidney
Fig. 18:
-Section through Abdomen at the level of the
second lumbar vertebra.
it is easy to demonstrate that the extra -peritoneal tissue in which it lies
becomes condensed in the regions above and below into obscure ligamentous
lamellae, but it is doubtful if these can have much effect in maintaining the
kidney in its place.
Hilum of the Kidney. — The internal border of the kidney
presents a longitudinal fissure called the hilum, for the
admission and egress of the vessels, nerves, lymphatics, and
duct (Fig. 185). This is bounded anteriorly and posteriorly
by a thick lip, and leads into a deep recess or cavity in the
kidney, which is termed the renal sinus. The ureter and the
renal vessels enter the kidney between the lips of the hilum.
They will be found to have the following general position
from before backwards: (1) branches of the renal vein;
(2) branches of the renal artery ; (3) ureter or renal duct.
ABDOMINAL CAVITY
489
Anterior Surface of the Right Kidney. — The anterior
surface of the right kidney may present three impressions,
viz., a hepatic, a colic, and a duodenal. The hepatic i?npression,
which indicates the area of contact with the under surface of
the right lobe of the liver, occupies almost the whole of the
upper two-thirds of the anterior surface, and corresponds to
the upper inclined plane. Over this district the kidney is
sometimes sunk deeply into the substance of the liver. The
suprarenal capsule, which rests, as a rule, on the upper
VENA CAVA
Superior mesenteric
vessels
Fig. 186. — Right Kidney and Duodenum.
extremity of the right kidney, extends downwards for a very
short distance on the anterior surface of the organ between
it and the liver. With the exception of this narrow strip
immediately adjoining the superior extremity, the hepatic
impression on the anterior surface of the kidney is covered
by peritoneum. The colic impression corresponds to the
inferior inclined plane, and sometimes it exhibits a marked
degree of obliquity. The hepatic flexure of the colon and
the commencement of the transverse colon are in contact
with this area. The posterior surface of these portions of
great gut is devoid of peritoneum, and bound to the kidney
by areolar tissue. The duodenal impression, or area of contact
49°
ABDOMEN
with the second part of the duodenum, is in the neighbourhood
of the hilum, and varies greatly both in position and extent
(Fig. 1 86).
Anterior Surface of the Left Kidney. — The suprarenal
capsule, the spleen, the stomach, and the pancreas are in contact
with the upper inclined plane on the anterior surface of the
left kidney. The suprarenal capsule, as a rule, occupies a
narrow district along the inner border from the level of the
hilum to the summit of the organ. The spleen is in contact
over an area immediately adjoining the outer convex border.
Splenic
flexure of
colon
FlG. 187. — Relations of the Left Kidney and the Pancreas.
The extent of this splenic field varies considerably in different
subjects. The pancreas stretches across the left kidney either
immediately above, or perhaps exactly over, the eminence
which intervenes between the two sloping surfaces on the
anterior aspect of the kidney. The stomach is in contact with
the left kidney over the triangular interval which is left be-
tween the suprarenal capsule, the spleen, and the pancreas,
and this surface is covered by peritoneum derived from the
lesser sac.
The inferior sloping surface on the anterior aspect of
the left kidney presents a varying relation to the intestinal
canal. Towards the outer border of the organ is the descend7-
ABDOMINAL CAVITY
491
ing colon, whilst the remainder of this surface is in relation to
the coils of the small intestine.
Posterior Surface of the Kidney. — This surface is mapped
out into an internal and an external district. The internal
district is the narrower of the two, and looks inwards and
backwards. It is in apposition with the psoas muscle and the
crus of the diaphragm, and a rounded ridge, which corresponds
to the angle between the planes of the psoas and quadratus
lumborum muscles, separates it from the external district.
The external district looks backwards. In its upper third it
rests on the diaphragm, and in its lower two-thirds upon the
Splenic artery
Colon
uprarenal
capsule
Crus of.
diaphragm
Duodenum
Colon
Spleen-'' \ ^
Left kidney
FlG. I
— Transverse section through Abdomen at the
level of the first lumbar vertebra.
1. Pancreas.
2. Splenic vein joining the portal
vein.
3. Aorta giving off the superioi
mesenteric artery.
4. Rod in bile-duct.
5. Inferior vena cava.
quadratus lumborum and the tendon of the transversalis
muscle. The upper end of the kidney curves slightly forwards
in correspondence with the diaphragm on which it lies, and it
should be borne in mind that between the diaphragm and the
last rib the pleural cavity descends behind the kidney for a
short distance (Fig. 189).
In spare individuals, when the kidneys have been hardened in situ,
dimples, corresponding to the tips of the transverse processes of the first,
second, and third lumbar vertebrae, and a shallow groove for the last rib,
may sometimes be detected on the posterior surface of the kidney. A
furrow corresponding to the ligamentum arcuatum externum is also not
infrequently to be seen on the posterior aspect of the kidney.
The student should never experience any difficulty in determining
492
ABDOMEN
the side to which a given kidney belongs. Even allowing that the
upper end cannot be distinguished from the lower end, or the anterior
surface from the posterior surface, by differences in their appearance
(which is frequently the case in a dissecting-room kidney), the ureter
alone is sufficient for the purpose. It shows the posterior surface from
its position at the hilum, and the lower end from its curving downwards
towards it.
Kidney Capsule and Kidney Substance. — The kidney is
invested by a strong fibrous coat, which can be easily stripped
Crus of diaphragm
Ligamentum
arcuatum externum /
Crus of diaphragm
Diaphragm
Spleen
Ligamentum
arcuatum
externum
Intestine In!
Fig. 189. — Dissection from behind to show the relation of the two Pleural
Sacs to the Kidneys. Outline of upper portions of kidneys indicated by
dotted lines.
from its surface. Divide this capsule along the outer margin
of the organ and peel it off towards the hilum. Here it
enters the renal sinus, lines its wall, and becomes continuous
with the sheaths of the vessels entering the gland, and also
with the external coat of the ureter.
Examine the manner in which the ureter or duct is con-
nected with the kidney. As it approaches the hilum it expands
into a wide funnel-shaped portion called the fle /vis (Fig. 190).
ABDOMINAL CAVITY
493
Calice
This enters the sinus and divides into two, or perhaps
three, large primary branches, and these again break up into a
large number of short stunted secondary divisions called calices
or infundibida, which are attached to the walls of the sinus.
The kidney should now be cut into two in the longitudinal direction.
Use a large knife, and,
entering it at the external
border, carry it steadily
through the gland sub-
stance to the hilum.
An examination
of the cut surface of
the kidney will show
that its substance is
arranged in two parts
— a medullary and a
cortical. The ?nedul-
lary portion is seen
to consist of dark-
coloured, faintly stri-
ated pyramidal
masses, the bases of
which are directed
towards the peri-
phery, whilst their
apices are free and
project into the sinus.
On the sinus wall each
of these appears in
the form of a pro-
minent mammillary
projection, called a
refial papilla, which
projects into one of
the calices of the
pelvis of the ureter
(Fig. 191). If the
Pelvis
Ureter
Fig. 190. — From a figure by Max Brodel to show
the form of the Pelvis of the Ureter and the
Calices, as well as the relation of the main
branches of the Renal Artery to these. The
ureter, pelvis, calices, and arteries were in-
jected with celloidin, and then the kidney
substance was removed by means of a digesting
fluid. It is thus a cast of the pelvis and calices
which is represented, and the cupped appearance
of each calyx shows the manner in which the
corresponding renal papilla projects into the
calyx.
kidney be squeezed
fluid will be seen to exude from these papillae, showing
that the tubuli uriniferi open upon their surface. The
number of pyramids and renal papillae vary from eight to
twenty. [ Usually there are more than twelve. A single calyx of
the ureter may surround one, two, 01 even three renal papillae,
494
ABDOMEN
R.P.
and receive the urine which issues from the papillary ducts
which open on their surface. The cortical substance con-
stitutes the peripheral part of the gland,
and also sends prolongations inwards
between the pyramids. These are
called the columns of Bertin (columnse
renales).
Ureter. — This is the duct which
carries the urine from the kidney to
the bladder. The relations of its ex-
panded upper end or pelvis at the hilum
of the kidney have already been noted.
Leaving the gland, it turns downwards
and becomes contracted, so that when
it reaches the level of the lower end of
the organ it has acquired the appear-
Fig. 191. — Diagram of ance of a cylindrical tube. The ureter
two Renal Papillae. extends downwards and inwards upon
the psoas muscle, and, crossing the
common or external iliac artery, it
enters the pelvis, where it will be after-
wards followed. In the abdomen
proper it is placed immediately behind the peritoneum, and
is crossed obliquely by the spermatic or ovarian vessels.
Before entering
the pelvis it passes
behind the ileum
on the right side,
and the pelvic
colon on the left
side.
Suprarenal
Capsules (gland-
ular suprarenales).
— These are two
small flattened
triangular bodies,
each of which is
placed upon the
upper end of the corresponding kidney. It surmounts
the kidney after the fashion of a helmet, and is prolonged
downwards for a short distance upon its anterior surface.
R.P. Renal papilla.
C. Cut edge of a calyx of
the pelvic portion of
the ureter.
Capsular vein
Surface in con
tact with live
Surface
covered by
inferior vena
cava
Surface
penton
Fig. 192. — Anterior Surface of Right Suprarenal
Capsule.
ABDOMINAL CAVITY
495
The suprarenal body lies in the epigastric region, and rests
upon the diaphragm.
The right suprarenal capsule is, as a rule, triangular in
form, and rests by its base upon the anterior and inner
aspect of the upper end of the right kidney. It is placed
between the posterior surface of the right lobe of the liver
and that portion of the diaphragm which covers the side of
the spine.
The anterior surface, which looks outwards as well as
forwards, presents two impressions — (i) The one is a narrow
flattened strip, adjoining the anterior border of the capsule,
which is overlapped by the inferior vena cava; (2) the second
impression comprises the re-
mainder of the anterior sur-
face, and is in contact with
the liver. Only a small and
variable part of the lower
portion of the anterior surface
of the right suprarenal capsule
is covered by peritoneum.
On the upper part of the
impression for the vena cava,
not far from the apex of the
capsule, a short fissure termed
the hilum may be observed.
From this issues a short wide
veinwhich immediatelyenters
the vena cava inferior. The posterior surface of the right
suprarenal capsule is divided by a salient curved ridge into
an upper flat part, which is applied to the diaphragm, and a
concave lower part, which is occupied with fat and rests
upon the kidney.
The left suprarenal capsule presents a semilunar form,
and as a rule is slightly larger than the right capsule. Its
position on the kidney is also somewhat different. It is
usually placed on its inner border immediately above the hilum.
The anterior surface presents, not far from its lower end, a
very obvious hilum with a large emerging vein. The greater
part of this surface is in relation to the postero -inferior
aspect of the stomach, and forms a portion of the bed in
which that organ lies. This gastric area of the suprarenal
capsule is clothed by peritoneum derived from the lesser sac.
Capsular vein
Fig. 193
Anterior Surface of Left
Suprarenal Capsule.
496 ABDOMEN
The lower portion of the anterior surface is covered by the
pancreas and crossed by the splenic vessels, and is not in
relation to the peritoneum. Sometimes the spleen extends
inwards so as to lie in relation to the upper part of the anterior
surface of the left suprarenal capsule, but this cannot be said
to be the rule. The posterior surface is subdivided into two
areas, as on the right side, by a curved ridge. The upper
area is flat, and applied to the left crus of the diaphragm ; the
lower area is hollowed out, and is in relation to the kidney, a
considerable amount of fat intervening.
The student has already observed the abundant nerve supply to the
suprarenal capsules from the solar plexus. Its blood supply is equally rich.
No fewer than three arteries enter its substance— viz. , the superior, middle,
and inferior capsular arteries.
When a section is made through the suprarenal capsule it is seen to
consist of an external firm portion termed the cortex, and of a soft pulpy
dark-coloured internal substance called the medullary part.
Dissection. — Having now disposed of all the viscera within the cavity
of the abdomen proper, the student should, in the next place, direct his
attention to the diaphragm — the great muscle which constitutes a movable
partition between the thoracic and abdominal cavities. Stripping the
peritoneum from its lower concave surface, clean the muscular fibres and
the central tendinous expansion towards which they ascend. In making
this dissection be careful to preserve the phrenic arteries which ramify upon
this aspect of the diaphragm and also the nerves which accompany them.
Diaphragm. — The diaphragm, after the heart, is the most
important muscle in the body. It forms the dome-shaped
roof of the abdomen, and the highly arched and convex
floor of the thorax. It is the chief muscle of respiration.
Each respiratory act is accompanied by its descent and ascent,
and in this way the capacity of the thoracic cavity is alternately
increased and decreased in the vertical direction. The vault
or cupola of the diaphragm is higher on the right side than
upon the left side of the body. In forced expiration it rises
on the right side as high as the upper margin of the fourth
rib, close to the sternum ; whereas, on the left side, it only
reaches the upper border of the fifth rib.
The ce?itral portion of the diaphragm is tendinous. From
this the fleshy fibres will be observed to radiate, and, at the
same time, to arch downwards, so as to obtain attachment to
the circumference of the lower aperture or outlet of the
thorax. In fro?it, it takes origin from the back of the lowest
segment of the sternum ; behind, it springs by two powerful
partly fleshy and partly tendinous processes, called the crura,
ABDOMINAL CAVITY
497
from the bodies of the upper three lumbar vertebrae, and upon
each side of these from two ligamentous arches, termed the
ligamenta arcuata ; laterally, it arises from the lower six costal
arches.
Anterior Attachment. — The sternal origin consists of two
slips which spring from the back of the xiphoid cartilage.
These are separated from each other by a narrow linear
interval filled by areolar tissue, and comparable with the wider
interval in the mesial plane behind, which separates the two
crura of the diaphragm.
Fig. 194. — Posterior Surface of the Anterior Wall of the
Thorax and Abdomen, to show the Costal and Sternal Origins
of the Diaphragm on the left side. (From LUSCHKA'S
Anatomy, modified.)
3. Ensiform cartilage.
5. Triangularis sterni.
6. Transversalis abdominis.
7. Sternal origin of diaphragm.
8. Costal origin of diaphragm.
10. Linea alba.
11. Musculo-phrenic artery.
Lateral Attach?nent. — The costal origin consists of six
pointed and fleshy slips which spring from the deep surfaces
of the lower six costal cartilages. These interdigitate with
the digitations of the transversalis abdominis. The sternal
and costal origins of the diaphragm are separated by a small
triangular interval, in which the pleural and peritoneal mem-
branes are merely separated from each other by some loose
areolar tissue. Through this gap the superior epigastric
branch of the internal mammary artery descends into the
abdominal wall.
vol. 1 — 32
498 ABDOMEN
Posterior Attachment. — The ligamentu??i arcuatum externum
is a fibrous band which stretches from the last rib to the
transverse process of the first lumbar vertebra. It arches in
front of the quadratus lumborum, and is merely the thickened
upper part of the fascia which covers this muscle, i.e., the
anterior lamella of the lumbar fascia. By pressing the rib
backwards the arch will be rendered more prominent. The
last dorsal nerve passes outwards and downwards under this
ligamentous arch. The liga??ientut?i arcuatum internum arches
over the psoas muscle, and, like the external ligament, is
simply a thickening of the fascia which covers that muscle.
It is the stronger of the two, and is attached by one extremity
to the tip of the transverse process of the first lumbar vertebra,
and by the other to the body of the second lumbar vertebra
and the tendinous part of the corresponding crus of the dia-
phragm. Fleshy fibres arise from both of these arcuate bands;
those from the internal ligament are more numerous and
better marked than those which take origin from the external
ligament, and they are continuous with the fleshy fibres of the
crus. Very frequently a gap or interval exists between the
fibres which spring from the ligamentum arcuatum externum
and those which arise directly from the last rib. The anterior,
lateral, and posterior attachments of the diaphragm are there-
fore marked off by intervals from each other.
The crura of the diaphragm are two thick fleshy processes
which descend upon the bodies of the upper lumbar vertebrae,
tapering as they proceed downwards, and finally ending in
pointed tendinous extremities. The right crus is the larger
and longer of the two. It takes origin from the bodies of the
upper three lumbar vertebrae, and the intervertebral discs
which intervene between them. The left crus springs from
the left side of the bodies of the first two lumbar vertebrae.
It is much smaller, and lies upon a plane posterior to the
right crus. Follow the crura upwards ; opposite the last
dorsal vertebra they will be observed to be connected across
the middle line by a strong fibrous band which arches over
the aorta. From the upper border of this fibrous arch fleshy
fibres arise which join both crura, and on this account we
give it the name of ligamentwn arcuatum medium.
It may be regarded as a law that wherever an artery pierces the origin
or insertion of a muscle, and comes to lie between bone and muscular
fibres, it is protected by a fibrous arch. Of this nature is the arch in
f
ABDOMINAL CAVITY 499
question, and also the fibrous arch thrown over the superior profunda artery
on the back of the humerus, and the fibrous arches in the adductor magnus
for the passage of the perforating arteries, and the femoral artery itself.
Above the level of the ligamentum arcuatum medium the
fleshy fibres of the crura diverge and ascend to join the
posterior border of the central tendon. The innermost
fibres of each crus, however, decussate so as to separate the
aortic from the oesophageal openings. The decussating
fasciculus of the right crus is always the larger of the two,
and moreover it usually passes in front of the decussating
fasciculus of the left crus.
Central Tendon. — The central tendon is exceedingly
strong. It is composed of strong tendinous bundles running
in different directions, and closely woven together so as to
give it a plaited appearance. This is well seen by an inspec-
tion of its abdominal surface. In shape the central tendon
resembles a trefoil leaf, of which the right lobe is the largest,
and the left lobe the smallest. Upon all sides it is sur-
rounded by muscular fibres. Those which spring from the
sternum are much the shortest.
Foramina of the Diaphragm. — The continuity of the
diaphragm is broken by three large openings, and by some
smaller apertures or fissures for the passage of the splanchnic
nerves, and the vena azygos minor. The three main open-
ings receive the names of the most important objects which
they transmit. They are —
1. The aortic.
2. The vena caval.
3. The oesophageal.
The aortic opening is in the mesial plane in front of the first
lumbar vertebra, and between the crura of the diaphragm.
It is bounded in front by the fibrous band which arches across
the middle line and connects the tendinous portions of the
two crura. The structures which pass through the aortic
opening are — (1) the aorta, (2) the thoracic duct, and (3) the
vena azygos major — in this order from left to right.
The vena caval opening is at a higher level, being situated
opposite the disc between the eighth and the ninth dorsal
vertebrae, in front and slightly to the right of the aortic open-
ing. It is placed in the back part of the central tendon at
the junction between its middle and right lobes. Its form is
somewhat quadrangular, and its margins are prolonged upon
5oo ABDOMEN
the walls of the vena cava as it passes through it. The con-
traction of the muscular fibres of the diaphragm will therefore
tend to increase the size of this opening and the calibre of
the vein which it holds.
In addition to the vena cava, one or two minute twigs
from the right phrenic nerve may be transmitted through the
vena caval opening.
The esophageal opening is an oval or elliptical foramen in
the muscular part of the diaphragm. It lies in front and
slightly to the left of the aortic aperture, and also at a higher
level, being placed opposite the tenth dorsal vertebra. In
some cases its upper or anterior border is tendinous, and
formed by the posterior margin of the central tendon.
Posteriorly it is separated from the aortic opening by the
decussation of the internal fibres of the crura.
The oesophageal opening transmits the gullet and the two
pneumogastric nerves.
The three large openings of the diaphragm, therefore, present very
different features. The aortic opening is a fibrous arch behind the
diaphragm, and it can in no way be affected by the contraction of the
muscular fibres. The vena caval opening \% in the central tendon, and its
margins are attached to the wall of the vessel which it transmits ; con-
traction of the diaphragm must therefore have a tendency to open this
aperture to its widest extent. The oesophageal opening is placed in the
muscular part, and consequently it is probable that the fibres which
surround it may be capable of exercising a constricting influence upon
the oesophagus, and in this way help to prevent regurgitation of food
during the descent of the diaphragm.
Little need be said regarding the smaller foramina. Each
crus is pierced by the three splanchnic nerves, and the left crus
is likewise perforated by the ve?ia azygos minor inferior. The
superior epigastric artery descends in the interval between the
sternal and costal attachments of the diaphragm, and the
niusculo-phrenic artery pierces the costal attachment opposite
the eighth or ninth rib.
Vessels on the Posterior Wall of the Abdomen.
Dissection. — The abdominal aorta and its branches and the vena cava
must now be cleaned. In doing this, care should be taken of the gangliated
cord of the sympathetic which extends downwards on the vertebral column
along the anterior border of the psoas. It is necessary to bear in mind
that the lumbar branches of the aorta, as they proceed outwards, pass
behind this. Separate the right crus of the diaphragm from the aorta, and
dissect in the interval between them. Here the receptaciilum chyli and the
ABDOMINAL CAVITY 501
vena azygos major will be found. A chain of lymphatic glands, termed
the lumbar glands, will be noticed in relation to the aorta. The only
branches of the aorta which are liable to injury are the spermatic arteries.
These are two slender arteries which spring from the front of the vessel a
short distance below the renal arteries. They are so small that they are
apt to be overlooked.
Abdominal Aorta (aorta abdominalis). — The abdominal
aorta is the direct continuation of the thoracic aorta, and
enters the abdomen through the aortic opening of the
diaphragm. It begins in the mesial plane in front of the
last dorsal vertebra, and it ends upon the left side of the
lower border of the body of the fourth lumbar vertebra by
dividing into the two common iliac arteries. It therefore
pursues an oblique course — inclining slightly to the left as it
proceeds downwards. A line drawn between the highest
points of the iliac crests would indicate the level of the
bifurcation of the abdominal aorta ; it takes place a little
below and to the left of the umbilicus.
Most of the structures which lie in front of the abdominal
aorta have been removed. In immediate relation to it from
above downwards are : — (1) The solar plexus and the layer of
peritoneum which forms the posterior wall of the lesser bag.
(2) The pancreas and splenic vein. (3) The third part of
the duodenum and the left renal vein. (4) The peritoneum
and the aortic plexus of nerves. Superficial to these it is
covered by the liver, the gastro- hepatic omentum and the
stomach, the transverse colon and its mesentery, and by the
great omentum and the coils of the small intestine. Behind,
the abdominal aorta rests upon the bodies of the lumbar
vertebrae and the intervertebral discs, separated from them.
however, by the anterior common ligament and the left
lumbar veins. On each side it is related in its upper part to
the crus of the diaphragm. On the right side the inferior
vena cava lies close to the aorta as high as the second
lumbar vertebra, but above this it is separated from it by the
fleshy part of the right crus. In the interval between the
right crus of the diaphragm and the vessel, the student has
already noted the receptaculum chyli and the vena azygos
major. On the left side, the left gangliated cord of the
sympathetic is in relation to the artery below the level of the
left crus.
Branches of the Abdominal Aorta. — The branches of the
abdominal aorta may be described under two heads, viz. —
502
ABDOMEN
(i) Those which come off in pairs. (2) Those which
arise si?igly.
Paired Branches.
1. Inferior phrenic arteries.
2. Middle capsular arteries.
3. Renal arteries.
Single Branches.
1. The cceliac axis.
2. The superior mesenteric.
3. The inferior mesenteric.
4. Spermatic or ovarian arteries. 4. The middle sacral.
5. Lumbar arteries.
With the exception of the ?niddle sacral, which arises from
the extremity of the aorta between the two common iliacs,
the single branches have already been described. The middle
sacral artery will be examined when the pelvis is dissected.
The paired branches may now be examined.
Inferior Phrenic Arteries (arterial phrenicae inferiores).
— These have already been noticed upon the under surface
of the diaphragm. They are two in number, and are the
first branches which spring from the abdominal aorta.
Diverging from each other, the artery of the right side passes
behind the inferior vena cava, whilst the artery of the left
side goes behind the oesophagus. Near the posterior border
of the central tendon of the diaphragm each divides into
an external and an internal branch. The external branch
proceeds outwards to anastomose with the intercostal arteries,
whilst the internal branch curves forwards in front of the
central tendon, and ends by anastomosing with its fellow,
and with the terminal branches of the internal mammary
artery. Each phrenic artery, in addition to the branches
which it supplies to the diaphragm, gives a twig, called the
superior capsular artery, to the suprarenal body. On the left
side it also sends a few minute branches to the oesophagus.
The phrenic veins open into the inferior vena cava.
Middle Capsular Arteries (arteriae suprarenales mediae). —
The middle capsular arteries are two small vessels which arise,
one from each side of the aorta, at the same level as the
superior mesenteric. They run outwards and upwards in
front of the crura of the diaphragm to the suprarenal bodies,
into the substance of which they sink. On the right side,
the middle capsular artery passes behind the inferior vena
cava. They anastomose freely with the superior and inferior
capsular arteries.
The right capsular vein opens into the inferior vena cava,
whilst the left vein ends in the renal or phrenic vein.
ABDOMINAL CAVITY 503
Renal Arteries (arteriae renales). — When compared with
the organs which they supply, the renal arteries are dispro-
portionately large. Only a small part of the blood which
they carry to the kidneys is used for the nourishment of the
gland substance. The kidneys are excretory organs, and it
is necessary that the blood should pass to them in large
quantity in order that certain materials may be removed
from it.
The renal arteries take origin about a quarter of an inch
below the superior mesenteric. Each artery proceeds out-
wards at right angles to the aorta, and, approaching the
kidney, breaks up into three branches, which enter the hilum,
and pass deeply into the renal sinus. It is overlapped by
the accompanying vein. Seeing that the aorta lies a little
to the left of the mesial plane, the right renal artery is the
longer of the two j the right artery is also placed at a
slightly lower level, and passes behind the vena cava. At
the hilum two of the terminal branches as a rule lie between
the renal vein and the pelvis of the ureter, whilst the third
enters the sinus behind the pelvis of the ureter. In the renal
sinus the three terminal branches break up into numerous
smaller branches, which penetrate the kidney substance in
the intervals between the renal papillae (Fig. 190, p. 493).
The renal artery gives a small branch — the inferior capsular
— to the suprarenal body, and also numerous fine twigs to
the connective tissue around the kidney.
The renal veins join the inferior vena cava. The vein of
the left side crosses in front of the aorta, and is the longer
of the two. Both receive tributaries from the suprarenal
bodies, and the left vein is also joined by the left spermatic
or ovarian vein.
Spermatic Arteries (arteriae spermaticae internae). — These
are two long slender vessels which spring from the front of
the abdominal aorta, a short way below the renal arteries.
Diverging from each other, each artery passes obliquely
downwards and outwards behind the peritoneum, to the
internal abdominal ring, where it joins the other factors of
the spermatic cord. As it descends, it rests upon the psoas,
and crosses the ureter and the external iliac artery. On the
right side, the spermatic artery passes in front of the vena
cava inferior and behind the terminal part of the ileum. On
the left side it proceeds downwards behind the iliac colon.
5o4 ABDOMEN
In the female, the corresponding arteries go to the ovaries,
and are consequently termed the ovarian arteries. Within
the abdomen proper they have the same relations as the
spermatic arteries. In the dissection of the female pelvis
they will be followed to their destination.
The right spermatic vein joins the vena cava directly, whilst
the left veifi terminates in the left renal vein. The ovarian
veins end in the same manner.
Lumbar Arteries (arteriae lumbales). — Four in number on
each side, they spring from the posterior aspect of the
abdominal aorta, in series with the intercostal arteries. At
present they are only seen in a very short part of their course.
They proceed outwards upon the bodies of the upper four
lumbar vertebrae, behind the gangliated cord of the sym-
pathetic, and then disappear under cover of the psoas
muscle and the series of fibrous arches from which the
muscle arises. The two upper arteries also pass behind the
crura of the diaphragm, and on the right side they are
crossed by the inferior vena cava.
The lu77ibar veins join the inferior vena cava, and those of
the left side pass behind the aorta.
Vena Cava Inferior. — This is the large vein which collects,
by means of its tributaries, the venous blood from the lower
limbs, the abdominal viscera, and a great part of the abdominal
parietes. It is formed on the right side of the body of the
fifth lumbar vertebra by the union of the two conunon iliac
veins. As it ascends, it lies in the first place upon the
vertebral column, close to the right side of the aorta : above
the level of the second lumbar vertebra it lies upon the
fleshy part of the right crus of the diaphragm, which inter-
venes between it and the aorta ; lastly, it is contained in a
deep groove, on the posterior surface of the liver, and leaves
the abdomen by passing through the vena caval opening of
the diaphragm, to open into the right auricle of the heart.
As it passes upwards it receives the following tributaries : —
1. The. common iliac veins.
2. The lumbar veins.
3. The right spermatic or ovarian vein.
4. The renal veins.
5. The right suprarenal vein.
6. The inferior phrenic veins.
7. The hepatic veins.
Common Iliac Arteries (arteriae iliacae communes). — The
ABDOMINAL CAVITY 505
two terminal branches of the aorta should next be examined.
They arise upon the left side of the body of the fourth lumbar
vertebra, and, diverging from each other, proceed downwards
and outwards upon the vertebral column. After a course of
about two inches, each vessel ends opposite the lumbo-sacral
articulation by dividing into the external and internal iliac
arteries ; of these the former is the larger of the two, and
appears to be the continuation of the parent trunk, whilst the
latter passes downwards into the pelvis.
The common iliac artery of each side is covered by
peritoneum, and overlapped by coils of the small intestine ;
furthermore, it is crossed by the large sympathetic twigs
which connect the aortic and hypogastric plexuses, and, close
to its termination, by the ureter. On the left side the superior
hemorrhoidal artery also passes down in front of the common
iliac artery.
No collateral branches of any consequence proceed from
the common iliac artery.
Common Iliac Veins (venas iliacas communes). — The
left common iliac vein is much longer than the right, and
stands in relation to both arteries of the same name. It
first lies along the inner or right side of its companion artery,
and then crosses behind the upper part of the right artery to
reach the vena cava inferior. The right common iliac vein at
first lies behind its companion artery, but, as it ascends, it
gradually comes to lie upon its right side, and here it joins
the vena cava. Each common iliac vein is formed by the
junction of the external and internal iliac veins.
The common iliac vein of each side is joined by the ilio-
lumbar vein. The left common iliac vein also receives the
?niddle sacral vein.
External Iliac Artery (arteria iliaca externa). — This vessel
is the first or abdominal portion of the great arterial trunk
which carries blood to the lower limb. It begins, as we have
seen, opposite the lumbo-sacral articulation, and extends
obliquely downwards and outwards along the brim of the true
pelvis to Poupart's ligament, behind which it passes into the
thigh, and becomes the fetnoral artery. Its course can be
indicated on the surface with tolerable accuracy by drawing a
line from a point a little below and to the left side of the
umbilicus to a point midway between the symphysis pubis and
the anterior superior spine of the ilium.
5o6 ABDOMEN
Like the common iliac artery, the external iliac is closely
covered by peritoneum. On the right side it passes behind
the terminal part of the ileum, whilst on the left side it
presents a similar relation to the pelvic colon. Towards
its termination it is crossed by the deep circumflex iliac
vein, and the genital branch of the genito-crural nerve.
In the male this part of the artery is also crossed by the vas
deferens, and in the female by the round ligament of the
uterus. At first the external iliac artery rests upon the inner
margin of the psoas muscle, but close to Poupart's ligament it
comes to lie directly in front of that muscle. The artery is
separated from the muscle, however, by the iliac fascia, to
which it is bound down by a condensed part of the extra-
peritoneal tissue, which passes over it. The genito-crural
nerve lies along the outer side of the artery, and the com-
panipn vein is placed on its inner side ; on the right side,
however, the vein, as it passes upwards, gradually comes to
lie behind the artery.
The external iliac gives off two large branches to the
abdominal wall, viz. — (i) the deep epigastric; (2) the deep
circumflex iliac. They arise close to Poupart's ligament, and
have both been examined (pp. 384, 385). The veins corre-
sponding to these arteries open into the external iliac vein.
External Iliac Vein (vena iliaca externa). — This, the con-
tinuation of the femoral vein, enters the pelvis on the inner
side of the corresponding artery by passing upwards behind
Poupart's ligament. It lies at first along the inner side of
the artery of the same name, but on a plane somewhat
posterior to it, and higher up on the right side it gets com-
pletely behind the artery. At the lumbo-sacral articulation
it ends by joining the internal iliac vein and forming the
common iliac vein. Immediately before its termination it
passes to the outer side of the internal iliac artery — between
it and the psoas muscle. Its tributaries are the veins corre-
sponding to the deep circumflex iliac artery and the deep
epigastric artery.
Deep Lymphatic Glands. — The dissector has, doubtless,
noticed a chain of lymphatic glands in connection with the
external iliac artery, the common iliac artery, and also extend-
ing upwards upon the vertebral column in relation to the
aorta and inferior vena cava. The external iliac glands are in
two groups — a lower and an upper. The former consists of
ABDOMINAL CAVITY 507
three glands placed one on each side and one in front of the
external iliac artery, and immediately above Poupart's liga-
ment. The inner gland receives the deep femoral lymphatic
vessels ; into the anterior gland is poured the lymph which
is drained from the district supplied by the deep epigastric
artery ; whilst the outer gland receives the lymph from the
district supplied by the deep circumflex iliac artery. The
efferent vessels from the lower group enter the higher group
of glands, and from these the lymph is passed on to the
common iliac and lumbar glands.
The glands in relation to either side of the aorta and
inferior vena cava are both numerous and large, and are
called the median lumbar glands. Their efferent vessels
terminate in two common lumbar lymphatic trunks, which
open into the receptaculum chyli.
Receptaculum Chyli (cisterna chyli). — This is the dilated
commencement of the thoracic duct. It is placed upon the
bodies of the first and second lumbar vertebrae, in the interval
between the right cms of the diaphragm and the aorta. To
bring it into view, it is necessary to separate the right crus
from the lumbar vertebrae and pull it aside. When fully dis-
played, the receptaculum chyli is seen to be a narrow elongated
sac about two inches in length, which receives by its lower
end the two common lumbar lymphatic trunks, whilst
superiorly, it contracts and becomes the thoracic duct.
About its middle it is joined anteriorly by the common in-
testinal trunk, whilst entering it near its upper end are two
lymphatic trunks which come from the lower intercostal
glands, and reach it by passing downwards through the
aortic opening. The vena azygos major lies along its right
side, but the receptaculum chyli is easily distinguished from
this by the whiteness of its walls. The thoracic duct enters
the thorax by passing through the aortic opening of the
diaphragm.
Azygos Veins. — The right azygos vein or vena azygos major
usually takes origin in the right ascending lumbar vein. It
will be found in the interval between the right crus of the
diaphragm and the aorta, upon the right side of the recep-
taculum chyli, and it will be noticed to enter the thorax by
passing through the aortic opening of the diaphragm.
The vena azygos mi?wr inferior is more difficult to discover.
It originates on the left side of the spine, in the left ascending
5o8 ABDOMEN
lumbar vein, and enters the thorax by piercing the left cms of
the diaphragm.
Fascia and Muscles on the Posterior Wall
of the Abdomen.
The muscles on the posterior wall of the abdomen are
three in number, viz. — (i) The psoas, an elongated fleshy
mass extending downwards on the side of the spine; (2)
The quadratics lumborum, a quadrate muscle external to the
psoas, and stretching between the crest of the ilium and the
last rib ; (3) The iliacus, situated in the iliac fossa. The
fascia which covers these muscles must, in the first place, be
studied.
Quadratus Lumborum Fascia. — Follow this inwards and
it will be found to be attached to the anterior aspect of the
roots of the transverse processes of the lumbar vertebrae.
Trace it outwards and it will be noticed to join the posterior
aponeurosis of the transversalis abdominis muscle. From
these connections the dissector will understand that this fascia
is simply the anterior lamella of the lumbar fascia. But what
are its superior and inferior attachments ? Above, it is fixed
to the last rib, and is thickened so as to form the ligamentum
arcuatum externum ; whilst inferiorly, it is attached to the ilio-
lumbar ligament. The quadratus lumborum muscle, therefore,
is enclosed in a sheath formed anteriorly by the anterior
lamella of the lumbar fascia, and posteriorly by the middle
lamella of the lumbar fascia (Fig. 141, p. 375).
Fascia covering the Psoas and Iliacus. — This is one con-
tinuous aponeurotic sheet. Above the level of the crest of the
ilium, where it is merely in relation to the psoas, it is thin and
narrow. Here it is attached externally to the fascia covering
the quadratus lumborum, whilst internally it is fixed to the
spine by a series of fibrous arches which bridge over the
lumbar arteries. Superiorly, it has been seen to form the
thickened band termed the ligame?itum arcuatum i?iternu?n.
Below, the fascia, expands so as to cover both the psoas
and the iliacus, and, at the same time, it becomes much
denser and thicker. Here it receives the name of the fascia
iliaca, and presents most important connections. The external
iliac vessels lie upon it, whilst the anterior crural nerve lies
behind it. The genito-crural nerve pierces it, and comes into
ABDOMINAL CAVITY 509
relation with the external iliac artery. Externally it is firmly
fixed to the crest of the ilium, whilst internally it sweeps over
the psoas, and is attached to the brim of the true pelvis.
These attachments can be easily demonstrated by dividing it
in the vertical direction, over the iliacus, a short way to the
outer side of the psoas. It is very loosely attached to the
subjacent muscles, so that the fingers can readily be passed
behind it, first in an outward and then in an inward direction.
Note that no perceptible fascial partition dips backwards from
it between the psoas and iliacus.
The inferior connections of this fascia have already been
studied (pp. 204 and 401). On the outer side of the iliac
vessels it has been seen to become continuous with the fascia
transversalis, and, at the same time, to be attached to Poupart's
ligament ; whilst behind these vessels it is carried downwards
into the thigh, to form the posterior wall of the femoral sheath.
Surgical Anatomy. — The attachments of the ilio-psoas fascia are of
high surgical importance. When an abscess forms in connection with the
lumbar vertebrce the pus readily passes downwards within the psoas sheath,
and in certain cases is conducted behind Poupart's ligament so as to point
in the thigh. It cannot enter the pelvis owing to the attachment of the
fascia iliaca to the ilio-pectineal line.
Dissection. — The muscles should now be cleaned and their attachments
defined ; but, in doing this, certain points must be attended to. The inner
portion of the fascia iliaca must be carefully preserved, in order that its
relation to the pelvic fascia may be afterwards made out. In the case of
the psoas muscle, care must be taken not to injure — (1) the sympathetic
cord, which lies along its anterior margin ; (2) the genito-crural nerve,
which runs downwards in front of it ; (3) the ilio-inguinal, and the external
cutaneous nerves, which appear at its outer border, and the anterior crural
nerve, which lies in the interval between it and the iliacus muscle. In the
case of the quadratus lumborum, bear in mind that the last dorsal nerve
runs outwards in front of this muscle, close to the lower border of the last
rib, and that the ilio-hypogastric and ilio-inguinal nerves cross it obliquely
at a lower level.
Quadratus Lumborum. — This muscle arises from the ilio-
lumbar ligament and from the crest of the ilium behind it.
It likewise receives two or three slips from the transverse
processes of a corresponding number of the lower lumbar
vertebrae. Narrowing slightly as it passes upwards, it is
inserted into the inner half of the last rib, behind the liga-
mentum arcuatum externum, and by four tendinous slips into
the tips of the transverse processes of the four upper lumbar
vertebrae.
Psoas Magnus. — This muscle has three distinct modes of
5i°
ABDOMEN
origin from the side of the vertebral column: — (i) by five
fleshy processes from the anterior surfaces and lower borders
of the transverse processes of the lumbar vertebrae close to
their roots; (2) by five slips, each of which arises from the
intervertebral disc and the contiguous margins of the bodies
of two vertebrae — the first slip springing from the last dorsal
and the first lumbar vertebrae and the intervening disc, and
the last slip from the two lower lumbar vertebrae and their
intervening disc ; (3) from the tendinous arches which bridge
over the lumbar arteries and protect these vessels from the
pressure of the contracting muscle.
The psoas tapers somewhat as it extends downwards along
the brim of the pelvis, and a tendon appears on its outer
border, which affords attachment to the fibres of the iliacus.
Passing behind Poupart's ligament, it is inserted into the
small trochanter of the femur.
Another muscle, called the psoas paiims, is occasionally present. This
springs from the bodies of the last dorsal and first lumbar vertebrae, and
the intervertebral disc between them, and, stretching downwards upon the
anterior and inner aspect of the psoas magnus, it ends in a tendon which is
inserted into the ilio-pectineal eminence and ilio-pectineal line.
Iliacus. — This muscle arises from the upper part of the
iliac fossa, the anterior ilio-sacral ligament, and the base of
the sacrum. It is inserted into the tendon of the psoas
magnus. Some of its fibres, however, have a separate insertion
into an impression below the small trochanter of the femur.
Nerves on the Posterior Wall of the Abdomen.
The nerves on the posterior wall of the abdomen are the
gangliated cord of the sympathetic and the anterior primary
divisions of the spinal nerves, with the branches which proceed
from them. These should now be dissected.
Gangliated Cord of the Sympathetic. — This enters the
abdomen behind the ligamentum arcuatum internum, and
extends downwards upon the bodies of the lumbar vertebrae
along the anterior border of the psoas muscle. Above, it is
continuous with the thoracic portion of the cord, whilst below,
it passes behind the common iliac artery and enters the pelvis.
In the thorax, it is placed upon the heads of the ribs ; here,
however, it lies nearer the middle line, being carried forwards
by the psoas muscle. On the right side, it is in great part
ABDOMINAL CAVITY 511
covered by the inferior vena cava, and on both sides the
lumbar vessels pass outwards behind it. As a general rule, a
small oval ganglion is formed upon the body of each lumbar
vertebra. Rami communicantes and peripheral branches of
distribution proceed from the ganglionic cord.
The rami communicantes connect the ganglia with the
anterior primary divisions of the lumbar spinal nerves. One
or more will be found accompanying each lumbar artery.
Trace them backwards by cutting through the fibrous arches
which bridge over these vessels and scraping away the fibres
of the psoas muscle. They join the lumbar nerves close to
the intervertebral foramina.
The rami communicantes consist of two sets, viz., white and grey.
The white rami communicantes are composed of medullated fibres which
pass from the spinal nerves to the gangliated cord. In the lumbar region
there are only two or at most three of these, and they proceed from the
upper two or three lumbar nerves. The grey rami communicantes are
much more numerous, and are formed of fibres which stream out in an
irregular manner from the sympathetic cord to all the anterior primary
divisions of the lumbar nerves.
The peripheral bra?iches of distribution consist of a large
number of small filaments which arise irregularly from the
lumbar gangliated cord and pass inwards to the aortic plexus.
Dissection. — To bring the anterior primary divisions of the lumbar
nerves into view, it is necessary to scrape away the psoas muscle. This
has already been partially done in following the connecting sympathetic
twigs backwards. An occasional branch, the accessory obturator, is liable
to injury unless it be secured at once. When present, it will be found
descending along the inner border of the psoas.
Lumbar Nerves. — The anterior primary divisions of the
lumbar nerves are five in number, and pass outwards in the
substance of the psoas muscle. They increase in size from
above downwards, and each nerve is joined by one or more
twigs from the sympathetic cord. Branches are given by
them to the psoas and quadratus lumborum muscles.
The first three lumbar nerves, with a part of the fourth,
unite in a loop-like manner to form the lumbar plexus, whilst
the remaining part of the fourth joins the fifth to form the
lumbosacral cord. The fourth lumbar nerve is frequently
called the nervus furcalis, seeing that it enters into the forma-
tion of both the lumbar and sacral plexuses.
Lumbar Plexus (plexus lumbalis). — This plexus is placed in
front of the transverse processes of the lumbar vertebrae in the
512 ABDOMEN
substance of the psoas. Above, it is usually connected with
the last dorsal nerve by a small twig, which descends in the
substance of the quadratus lumborum, to the first lumbar
nerve ; below, it is brought into communication with the sacral
plexus by the branch of the fourth nerve, which enters into
the formation of the lumbo-sacral cord.
The following are the branches which proceed from the
lumbar plexus : —
1. Iliohypogastric, \ t • i r . , *
T1. • Jr ■ , !- derived from ist lumbar nerve.
2. llio-ingmnal, J
3. Genito-crural, ,, 1st and 2nd lumbar nerves.
4. External cutaneous, ,, 2nd and 3rd lumbar nerves.
5. Obturator, ,, 2nd, 3rd, and 4th lumbar nerves.
6. Anterior crural, ,, 2nd, 3rd, and 4th lumbar nerves.
7. Muscular branches to the quadratus lumborum and psoas muscles
which arise somewhat irregularly.
The manner in which these nerves spring from the plexus
may now be studied. The first lumbar trunk breaks up into
four branches, viz., the ilio-hypogastric, the ilio-inguinal, the
upper root of the genito-crural, and a communicating branch
to the second lumbar nerve. The second, third, and fourth
lumbar trunks each divides into an anterior and a posterior
division. The three anterior divisions are smaller than the
others, and they unite to form the obturator nerve ; the three
large posterior divisions unite to form the anterior crural
nerve. But other branches come off from certain of these
divisions. Thus, the lower root of the genito-crural springs
from the anterior division of the second lumbar nerve, whilst
the two roots of the external cutaneous nerve take origin
from the posterior divisions of the second and third lumbar
trunks.
The ilio-hypogastric nerve emerges from the outer border of
the psoas, and crosses the quadratus lumborum obliquely.
Reaching the crest of the ilium, it leaves the abdomen by
piercing the transversalis muscle. Its further course has
already been studied (p. 374). It is distributed by an iliac
branch to the skin of the gluteal region, and by a hypogastric
branch to the skin over the lower part of the abdominal wall.
The ilio-inguinal nerve is smaller than the ilio-hypogastric,
and leaves the psoas almost at the same point. It runs
obliquely downwards and outwards over the quadratus lum-
borum and the upper part of the iliacus, and disappears from
view by piercing the transversalis muscle a little way in front
ABDOMINAL CAVITY
o1 5
of the ilio-hypogastric. It is distributed to the integument
of the scrotum and the inner aspect of the thigh (pp. 361
and 374).
The genito-crural Jierve (nervus genito-femoralis) is directed
forwards through the psoas, and, appearing upon its anterior
aspect, ends by dividing into a genital and a crural branch.
The genital branch proceeds downwards and inwards, and,
crossing the external iliac artery, reaches the internal ab-
o.xn
i_.ni
HYPOGASTRIC
INGUINAL
L.IV
L.V
extVcutaneous
ANT? CRURAL
LUMBO-SACRAL
CORD
OBTURATOR
Fig. 195. — Diagram of Lumbar Plexus.
dominal ring. Here it joins the other constituents of the
spermatic cord, and, leaving the abdomen, is distributed to
the cremaster muscle. In the female the genital branch is
very small, and ends in the round ligament of the uterus and
the labium pudendi. The crural branch runs downwards
along the outer side of the external iliac artery, and, crossing
the deep circumflex iliac artery, passes behind Poupart's liga-
ment. It supplies a limited portion of the integument in
front of the thigh.
vol. 1 — 33
5*4
ABDOMEN
The external cutaneous nerve (n. cutaneus femoris lateralis)
of the thigh emerges from the outer border of the psoas about
its middle, and descends obliquely across the iliacus muscle
behind the fascia iliaca to the anterior superior spine of the
ilium. At this point it leaves the abdomen by passing behind
Poupart's ligament. It supplies the skin upon the outer
aspect of the thigh.
The anterior crural nerve (nervus femoralis) is the largest
branch of the plexus. It runs downwards in the interval
between the psoas and iliacus, and passes from the abdomen
Iliohypogastric
Ilioinguinal
Genito-crural
Twelfth ri
Last dorsal nerv
Ilio-hypogastric
Ilio-inguinal
Genito-crural
Quadratus
lumborum -C-
External
cutaneous / /
Up
Iliacus
Anterior crural
Anterior crural
Obturator
Lumbo-sacral
cord
Lumbo-sacral cord
Fig. 196. — The Lumbar Plexus (semi-diagrammatic).
behind Poupart's ligament. It gives a branch to the iliacus
muscle.
The obturator nerve (n. obturatorius) emerges from the inner
border of the psoas, where this muscle reaches the brim of
the pelvis, and extends forwards upon the inner wall of the
pelvis a short way below the ilio -pectineal line of the in-
nominate bone. At the upper part of the thyroid foramen
it joins the artery of the same name, and, escaping from the
pelvis,' enters the thigh.
A small nerve, the accessory obturator, is occasionally to be
found. It may either spring directly from the obturator or
ABDOMINAL CAVITY 515
from the third and fourth lumbar nerves. It proceeds down-
wards along the inner side of the psoas, and it enters the
thigh by passing over the pubic bone under cover of the
pectineus. Here it gives branches to the hip joint, and
unites with the obturator nerve. It also occasionally supplies
a twig to the pectineus muscle.
Lumbo- sacral Cord (truncus lumbosacralis). — This large
nerve trunk is formed by the union of the anterior primary
division of the fifth lumbar nerve with the descending branch
of the fourth lumbar nerve. It passes downwards over the
base of the sacrum into the pelvis, and joins the sacral plexus.
Last Dorsal Nerve. — The anterior primary division of this
nerve will be found running outwards in front of the quadratus
lumborum, and under cover of the fascia spread over that
muscle, along the lower border of the last rib. Near the
spine it sends a small offset downwards to the first lumbar
nerve, and at the outer border of the quadratus lumborum it
pierces the aponeurosis of the transversalis abdominis, and
then passes forwards in the abdominal wall between this
muscle and the internal oblique. Its course and distribution
in the wall of the abdomen have already been described (pp.
36l> 374).
Lumbar Arteries (arteriae lumbales). — These have been
traced to the inner border of the psoas. They are now
observed to pass backwards behind this muscle to the
intervals between the transverse processes of the vertebrae.
Here each ends by dividing into a dorsal and an abdominal
branch.
The dorsal branch runs backwards between the transverse
processes, and, after giving a spi?ial branch, which enters the
spinal canal through the intervertebral foramen, ends in the
muscles and integument of the back.
The abdominal branches, with the exception of the last,
proceed outwards behind the quadratus lumborum, and are
then directed forwards between the abdominal muscles, where
they anastomose, above with the intercostal arteries, below
with the deep circumflex iliac and ilio-lumbar arteries, and in
front with the superior and deep epigastric arteries. The
last abdominal branch, as a rule, passes in front of the
quadratus lumborum.
Lumbar Veins (venae lumbales). — These vessels accompany
the corresponding arteries, and pour their blood into the inferior
1— 33 a
5i6 ABDOMEN
vena cava. The veins of the left side pass behind the aorta.
In front of the transverse processes of the vertebrae, cross
branches link together the different lumbar veins on each
side of the vertebral column, and form a continuous longi-
tudinal vessel, called the ascending lumbar vein. By its upper
end this venous trunk is connected with the corresponding
azygos vein.
Subcostal Artery. — At this stage of the dissection the
subcostal artery, the last parietal branch of the thoracic
aorta, will be seen crossing the upper part of the quadratus
lumborum in company with the last dorsal nerve. It lies in
series with the abdominal branches of the lumbar arteries.
Dissection. — The lower limbs having, by this time, been removed from
the trunk, the pelvis may also be detached. Place a ligature around the
aorta and vena cava at the level of the bifurcation of the former, and divide
them immediately above this point. Then carry the knife through the
intervertebral disc which intervenes between the third and fourth lumbar
vertebrae, and, having cut the nerves and soft parts, complete the separation
of the pelvis from the remainder of the trunk by means of the saw.
PELVIS.
The pelvis is the basin-shaped lower part of the abdominal
cavity. It has already been denned as being that portion
of the general cavity of the abdomen which lies below and
behind the ilio-pectineal lines of the innominate bones.
Its walls are, for the most part, rigid and composed of bone ;
behifid, it is bounded by the sacrum and coccyx ; whilst in
front and laterally, it is bounded by the two ossa innominata.
The bony wall, however, is deficient at certain points ; thus,
posteriorly, there is an interval on each side, between the
sacrum and the os innominatum, which is partially filled up
by the sacro-sciatic ligaments ; again, laterally, there is the
wide thyroid foramen, which is closed by the thyroid mem-
brane ; and, in fro?it, there is the gap left by the pubic arch,
which is occupied by the triangular ligament of the urethra.1
Upon the inner aspect of these boundaries of the pelvis
there are placed certain muscles. Posteriorly, upon the
anterior aspect of the sacrum, are the two pyriformes
1 Let it be clearly understood that it is the inferior or superficial layer of
the triangular ligament to which we refer, and not the ' ' deep layer. "
PELVIS 517
muscles ; laterally, upon the inner aspect of each innominate
bone, is the obturator inter mis 77iuscle ; whilst, in front, lying
against the deep surface of the triangular ligament, is the
compressor urethra muscle. But, in addition, there is a strong
aponeurotic membrane, called the parietal layer of the pelvic
fascia, which forms a complete lining for the pelvis, and is
placed upon the deep surface of these muscles.
The pelvic wall may therefore be regarded as consisting
of three strata, each composed of parts which lie in the
same morphological plane, viz. : —
1. A bony, ligamentous, and membranous stratum.
2. A muscular stratum.
3. An aponeurotic stratum.
The pelvic cavity is closed below, and separated from the
perineum by the visceral layer of the pelvic fascia, which passes
inwards to the viscera from the parietal layer of the same
aponeurosis, and also by the pelvic diaphragm, which is placed
upon the under surface of the fascia. This diaphragm con-
sists of the two levatores ani muscles and the two coccygei muscles.
The pelvic and abdominal cavities are directly continuous
above and in front through the pelvic inlet.
The contents of the pelvic cavity differ in the two sexes ;
in both, however, the bladder occupies the fore-part, and the
rectum and pelvic colon the back-part, of the space. The
difference is to be found in the generative organs. It is
necessary, therefore, to describe the male and female pelvis
separately.
Male Pelvis.
Within the male pelvis we find the following structures : —
1. The pelvic colon and rectum.
2. The bladder, with the lower portion of the
Viscera. ureters, the prostate, and the prostatic
portion of the urethra.
3. Vasa deferentia and the vesicuke seminales.
1. The internal iliac vessels and their branches.
2. The superior hemorrhoidal vessels.
Blood-Vessels. -I 3. The middle sacral vessels.
4. Certain venous plexuses in connection with the
viscera.
[ 1. The sacral plexuses and their branches.
Nerves. - 2. The obturator nerves.
{ 3. The pelvic part of the sympathetic.
The peritoneum dips into the pelvis, and completely
5i«
ABDOMEN
invests the pelvic colon, and at the same time gives a partial
covering to the rectum and the bladder.
General Position of the Viscera. — The pelvic colon and
the rectum occupy the back part of the pelvic cavity. The
rectum takes a curved course downwards upon the lower part
of the sacrum and upon the coccyx, to the concavity of both
of which it is adapted. The bladder is placed in the fore-
part of the cavity, and lies against the pubic bones. Between
Lateral wall
of pelvis
Paravesical fossa
Reflection of
peritoneum
Empty bladder
Symphysis pubis
Retro-pubic
pad of fat
Corpus
cavernosum~|
Corpus spongio- |
sum containing
urethra
Bulb of the
Ureter
Vas deferen
Middle peri
toneal fossa
Sacro-genit
fold
Vas deferer
Ejaculator urinae
Cowper's gl
Sphincter ani
in tern us
Sphincter ani
externus
Fig. 197. — Mesial section through the Pelvis. The bladder, which is empty,
does not present the usual form.
the bladder and the rectum are the vesiculce seminales and
the vasa deferentia, whilst placed below the bladder and
embracing its neck, or urethral orifice is the prostate. At the
present moment the pelvic colon, the rectum, and the bladder
are the only viscera visible.
Disposition of the Peritoneum. — The peritoneum is
continued from the posterior wall of the abdomen into the
pelvic cavity, and gives a lining to its walls as well as coverings
to certain of the contained viscera. It invests the pelvic
PELVIS 519
colon completely, and connects it by means of a fold, called
the pelvic meso-colon, to the anterior surface of the sacrum.
At the junction of the pelvic colon with the rectum, opposite
the third piece of the sacrum, the peritoneum leaves the
posterior surface of the gut ; still lower down it passes away
from its lateral surfaces ; and finally, at a point about one
inch above the base of the prostate, or about three inches
above the anal orifice, it leaves the anterior surface of the
rectum, and is reflected forwards on to the vasa deferentia
and the vesiculae seminales, as these lie in relation to the
base of the bladder. Below this reflection the rectum is
absolutely destitute of peritoneal covering.
When the bladder is empty the peritoneum is carried
upwards on the vasa deferentia and the seminal vesicles, and
then, leaving these viscera, it is folded on itself and forms a
short fold with a sharp free crescentic border. This fold is
termed the sacro-genital fold (Dixon), and takes a transverse
course in the interval between the bladder and the rectum.
If the fingers are passed down into the space between this
fold and the rectum, they enter the recto-vesical or recto-genital
pouch of peritoneum, the bottom of which represents the
reflection of the membrane from the gut, on to the seminal
vesicles and vasa deferentia.
The anterior layer of the sacro-genital fold is reflected
forwards on to the bladder, and gives a covering to its
superior surface. At the apex of the bladder the peritoneum
is conducted on to the posterior aspect of the anterior
abdominal wall by the urachus.
The level at which the peritoneum is reflected from the rectum, or, in
other words, the level of the bottom of the recto-genital pouch, is subject to
variation. In certain cases it is placed nearer to the base of the prostate
than is stated above.
Peritoneal Fossae. — When the bladder and rectum are
empty the portion of the pelvic cavity on either side of these
viscera is seen to present three depressions or peritoneal
fossae. Posteriorly, at the side of the empty rectum, is the
pararectal fossa ; anteriorly, at the side of the empty bladder,
is the paravesical fossa ; whilst occupying a place between
these, and on the outer side of the seminal vesicle, is the
much smaller middle fossa (Dixon and Birmingham).
These three fossae on each side are separated from each
other by two well-marked peritoneal folds or ridges, which
52o ABDOMEN
pass outwards from the viscera towards the wall of the pelvis.
8 10
FlG. 198. — The Peritoneum of the Pelvic Cavity.
The upper part of the posterior wall of the pelvis has been removed to show more clearly
the disposition of the peritoneum within its cavity. (Dixon and Birmingham.)
1. Vas.
2. Obliterated hypogastric artery.
3. Deep epigastric artery.
4. External iliac vessels.
5. Obturator nerve.
6. Obliterated hypogastric artery.
7. Ureter.
8. Third sacral vertebra.
9. Lower part of pelvic mesocolon.
10. Rectum.
11. Pararectal fossa.
12. Sacro-genital fold.
13. Lateral portion of middle fossa.
14. Obturator fossa.
15. Trigonum femorale.
16. Paravesical fossa.
17. Median portion of middle fossa.
18. Plica vesical is transversa.
19. Urachus.
20. Bladder.
The anterior fold or ridge contains the ureter, and stretches
from the lateral basal angle of the empty bladder outwards and
PELVIS 521
backwards to the lateral wall of the pelvis. The second fold
is the sacro-genital fold, which bounds the recto -vesical or
recto-genital pouch in front, and has already been seen in the
interval between the rectum and bladder. This fold curves
outwards and backwards on each side towards the sacrum,
and gradually fades away. It contains between its layers
the sacro-genital ligament, composed of some fibrous and
muscular tissue, which stretches from the seminal vesicles
to the sacrum at the side of the rectum.
The pararectal fossa is a very evident peritoneal depression
at the side of the empty rectum. It is occupied, as a rule,
by a portion of the pelvic colon ; but when the rectum
becomes distended, the expanding gut strips off the peritoneum
from the posterior wall of the pelvis, invades the fossa, and
greatly reduces the size of the depression. The pararectal
fossae of the two sides become continuous with each other
in front of the rectum, across the bottom of the recto-vesical
or recto-genital pouch. The paravesical fossa at the side of
the empty bladder is occupied by coils of small intestine, or
perhaps by the pelvic colon. It becomes to a great extent
obliterated, as the bladder distends and approaches on each
side the lateral wall of the pelvis. A transverse fold of
peritoneum is frequently seen stretching across the superior
surface of the bladder, and traversing to a greater or less
extent the paravesical fossa. This is the plica vesicalis trans-
versa. The middle or genital fossa is bounded in front by the
fold of the ureter, and behind by the sacro-genital fold. As
the bladder distends it invades this depression, and at the
same time opens out and obliterates, to a large extent, if not
entirely, the sacro-genital fold, which limits it posteriorly.
False Ligaments of the Bladder. — Wherever the peritoneum leaves
the bladder to reach the pelvic or abdominal wall, the reflection which
takes place is termed a false ligament. The peritoneum as it quits the
side of the bladder, and passes on to the lateral wall of the pelvis, forms
the lateral false ligament ; as it is conducted from the apex over the urachus
to the posterior aspect of the anterior abdominal wall it forms the anterior
or superior false ligament. The term posterior false ligament had better be
abandoned ; it was previously employed to indicate the sacro-genital fold
which, as we have seen, is not directly connected with the bladder.
Hypogastric Nerve Plexus (plexus hypogastrics). — This
is the lowest of the three great prevertebral plexuses, and is
the main source from which the pelvic viscera are supplied
with nerves. It is a dense flattened plexus, which lies in
522
ABDOMEN
Peritoneum
Pelvic fascia
Pelvic wall
Levator ani
Pelvis
front of the body of the last lumbar vertebra in the interval
between the two common iliac arteries. Superiorly, it is
joined by numerous large filaments, which proceed downwards
from the aortic plexus and the lumbar ganglia. Inferiorly,
it ends by dividing into two lateral parts which are con-
tinued downwards on the back wall of the pelvis, and
along the inner side of the internal iliac vessels to the pelvic
plexuses.
Pelvic Fascia. — Much of trie difficulty which is involved
in the study of the pelvic fascia will be removed if the student
will constantly keep before him two facts regarding it, viz. —
(i) That it constitutes a continuous lining for the inner
surface of the pelvic wall. (2) That it sends across the
pelvic cavity a layer which
acts as a partition between
the pelvis proper and the
perineum. The lining -
portion of the fascia may
be termed the parietal part,
and the partition -portion
the visceral part. If the
pelvis contained no viscera,
the arrangement would be
exceedingly simple, and
might be represented dia-
grammatically as in Fig.
199.
The visceral layer, how-
ever, comes into relation with the viscera, and the connections
which it forms with these give rise to the complexity of the
membrane.
In order to obtain a proper display of the pelvic fascia,
it is necessary to dissect it from three different aspects, viz.
— (1) from above; (2) from below; (3) from the side.
The arrows in the diagram indicate the directions in which
the dissection must be made. It will be found more con-
venient to make the dissection on the right side.
Dissection from above. — This dissection is undertaken with the view of
exposing the pelvic aspect of the fascia. Strip the peritoneum from the
right side of the pelvic wall by means of the fingers. It should also be
partially removed from the same side of the bladder. On carefully scraping
away the loose fatty extra-peritoneal tissue with the handle of the knife, or,
better still, with the finger-nails, the pelvic fascia will be brought into
Fig. 199.
Permeum
—Diagram of the Pelvic Wall
and Pelvic Floor.
PELVIS 523
view. To expose it in front, the bladder must be forcibly dragged back-
wards from the pubic bones, and the intervening areolar tissue taken away.
At this point the pelvic fascia will not be encountered until we have
descended to within half an inch or so from the lower end of the sympk;.
Here it is so thick that it is beyond injury so long as we work with the
fingers, or the handle of the knife, but laterally it is thin, and great care
must be taken. The extra-peritoneal tissue which surrounds the internal
iliac vessels must also be removed, and the relation of their parietal
branches to the fascia made out.
Gluteal
vessels and
superior
gluteal nerve
Pyriformis
Great sciatic
nerve
Pudic vessels and
nerve, and nerve to
obturator internus
Obturator internus
Small sciatic nerve
Sciatic artery
External
cutaneous
nerve
Iliacus
Poupart's
ligament
Anterior
crural nerve
Psoas
Femoral
vessels
Fig. 200. — The dotted lines indicate the directions in which the saw
must be carried through the bone. (Arthur Thomson. )
Dissection from below. — The object of this dissection is to expose the
perineal surface of the fascia. The pelvis must be placed so that the outlet
looks upwards. The fat having previously been removed from the ischio-
rectal fossa, divide the inferior hemorrhoidal vessels and nerves if they are
still present, and then raise the levator ani muscle from the side of the
rectum. To do this the muscle must be cut transversely about an inch
above the anus. At first the levator ani will be observed to rest upon the
side of the gut, separated from it, however, by a thin but distinct layer of
fascia (the rectal layer of pelvic fascia), but, as the dissector proceeds with
the dissection, the muscle will be found higher up to be in close contact
with the under surface of the visceral layer of the pelvic fascia. Lastly,
he will come to the line of origin of the muscle from the pelvic fascia, i.e. ,
524
ABDOMEN
the line along which the visceral layer leaves the parietal layer — and here
he must stop.
In the dissection of the ischio-rectal fossa (p. 328), the parietal pelvic
fascia was exposed and recognised as forming the outer wall of the space.
The entire inner surface of the parietal portion, both in its pelvic and
perineal parts, is, therefore, now displayed, and, if the levator ani be
drawn outwards and the pelvis held up to the light, the visceral pelvic
fascia will be seen passing inwards from the parietal part of the aponeurosis
to the viscera.
Gluteal vessels
and superior
gluteal nerve
Pyriformts
Great
sciatic
nerve
Spine of ischium
Pudic vessels and
nerve, and nerve to
obturator internus
Small sciatic nerve
Sciatic artery -
Great sacro-sciatic _
ligament
Fig.
Obturator
internus
drawn for-
wards
-The white line of the pelvic fascia is seen in shadow.
(Arthur Thomson. )
But it is also necessary to obtain a view of the outer aspect of the
parietal pelvic fascia, and, for this purpose, the following dissection may
be made.
Dissection from the side, — To reach the pelvic fascia from this aspect a
portion of the bony wall of the pelvis must be removed, and the obturator
internus muscle raised from its position. The outer aspect of the in-
nominate bone must first be thoroughly cleaned, by removing the remains
of the obturator externus muscle and all adhering portions of muscle from
the pubic and ischial bones ; carefully preserve, however, the obturator
nerve and artery as they emerge from the upper part of the thyroid
foramen. The membrane which closes the thyroid foramen may also be
taken away, with the exception of a small portion immediately adjoining
PELVIS 525
the canal under the pubic bone, through which the obturator vessels and
nerve emerge. This will expose a part of the outer surface of the obturator
internus muscle, and the parietal pelvic fascia will be observed arching
over the border of the muscle to join the thyroid membrane below the
obturator vessels. Next, define the great and small sacro-sciatic foramina
and the structures which emerge from and enter the pelvis through these
apertures.
The section of the bone may now be made. This simply consists in
taking away that portion of the innominate bone which bears the acetabulum.
The first step is to saw through the spine of the ischium, close to its base.
The bone must then be sawn through above and below the acetabulum —
( 1 ) the first cut should pass through the ischial tuberosity from the lower end
of the thyroid foramen to the lower end of the small sciatic notch ; (2) the
second cut should extend from the upper part of the thyroid foramen to the
upper part of the great sciatic notch. The direction in which the saw is to
be carried in making these sections is indicated by dotted lines in Fig. 200.
In the case of the second section, the direction will be somewhat influenced
by the depth of the acetabulum. In no case, however, is it wise to enter
the saw lower than the anterior inferior spine of the ilium. This is the
point at which the cut should be commenced. In all probability it will be
found necessary to complete this section in front by means of the bone
pliers, as there are many cases in which it is impossible to bring the saw
out at the two points indicated. Care must be taken not to break the
ascending ramus of the pubic bone. In carrying out the first or lower
section, the dissector will meet with no difficulty whatever.
The section of bone being successfully performed, the detached portion
should be raised from the subjacent obturator internus. The fibres of this
muscle take origin from the deep surface of the bone, and it will thus be
necessary to use the knife in effecting the separation. Lastly, clean the
obturator internus, and, grasping its tendon, draw it gently outwards and
upwards, as in Fig. 201. The outer aspect of the parietal pelvic fascia
comes into view. By this dissection the student is afforded a striking
illustration of the three morphological planes, the bony, muscular, and the
aponeurotic, referred to on p. 517 as entering into the composition of the
pelvic wall.
Description of the Pelvic Fascia. — The dissector has
already taken note of a continuous fascia lining the interior
of the abdomen proper, and placed between the muscles on
the one hand, and the extra -peritoneal fatty tissue and
peritoneum on the other. In relative position the pelvic
fascia is identical with the abdominal fascia, and the visceral
layer of the former, which passes inwards upon the upper
surface of the pelvic diaphragm, may be compared with the
thin cellular layer which clothes the under surface of the
abdomino - thoracic diaphragm ; the one completes the
aponeurotic wall of the great abdominal cavity below, whilst
the other completes it above. But, whilst this is the case, it
must be borne in mind that the abdominal and pelvic fasciae
are only directly continuous with each other over a very
limited part of the posterior portion of the ilio-pectineal line.
526 ABDOMEN
Parietal Pelvic Fascia. — The parietal or lining portion
of the pelvic fascia must be examined from three different
points of view, viz. — (i) posteriorly; (2) laterally; (3)
anteriorly. On the posterior wall of the pelvis, the parietal
pelvic fascia is of little importance. It is simply represented
by a thin membrane, covering the anterior aspect of the
pyriformes muscles, and the sacral plexus of nerves. It is
in consequence frequently described under the name of the
fascia of the pyriforniis.
Laterally, it is strong and dense, and in this situation it
covers the inner surface of the obturator internus muscle.
Superiorly, it is attached for a distance of about one inch
to the back part of the ilio-pectineal line, where it will be
observed to be directly continuous with the fascia iliaca, which
is inserted into the same line ; but the attachment of both
to the bone is weak ; so that by passing a probe down behind
the latter the continuity of the two membranes can be deter-
mined. In front of this, the line of attachment of the
parietal pelvic fascia leaves the ilio-pectineal line ; it descends
obliquely along the superior border of the obturator internus
muscle to the upper margin of the thyroid foramen, and,
opposite the groove on the under surface of the ascending
ramus of the pubic bone, there is a break in its bony
attachment. At this point it turns over the margin of
the obturator internus, and, joining the thyroid membrane
on the other side, forms a sharp falciform edge which
converts the groove into a canal. From this onwards the
line of attachment gradually sinks upon the posterior aspect
of the body of the pubis, and, in front, it is found as low
as the inferior border of the symphysis. There is thus a
considerable part of the inner surface of the pelvis below the
level of the ilio-pectineal line and the crest of the pubis
devoid of fascial lining. Here no continuity can be shown
to exist between the iliac and pelvic fasciae, except through
the medium of the periosteum.
From the line of attachment thus indicated the parietal
pelvic fascia descends upon the inner or deep surface of the
obturator internus muscle, and is attached inferiorly to the
tuberosity of the ischium through the medium of the falciform
edge of the great sciatic ligament, and also behind this to
that ligament itself. Traced forwards, it will be found to be
fixed to the rami of the pubis and ischium {i.e., the side of
PELVIS
527
the pubic arch) in front of the obturator interims. In this
manner, therefore, it may be said to have an attachment to
the pelvic outlet from the symphysis to the sacrum. When
followed backwards, the fascia will be noticed to pass over
5th lumbar vertebra Promontory of sacrum
Common iliac artery I J
Internal iliac artery v \
Obliterated hypogastric artery and
>uperior vesical arterv \
k
r superior spine of ilium "\ *^ fW&'-ZtXn
External iliac vessels -J^fcar .
Anterior division of \4^jj^k*m Ar*v-' ^aW'V ■'' * 9^^ -'^-
internal iliac artery ^Pif^^EF-' -'Jr '-^'?\§r '' B^"*--*!
Obturator artery .^rM^P^SfVyT -'A* <rWfi»,V^P''
and nerve JBj^^gglPjyp' x^r ^^ar jllllB o£?
Symphysis aw^\ J&R ~~>UsJ -''^A^ WfcSi
Ilio-lumbar artery
ternal iliac vein
Lateral sacral arteries
Parietal pelvic fascia
covering obturator internus
White line or arcus tendineus
Visceral pelvic fascia
Constrictor urethrae
Deep layer of triangular ligament
Superficial layer of triangular ligament
Am
^Coccygeus (covered by
parietal pelvic fascia)
Pyriformis (covered by parietal
pelvic fascia) .
Internal pudic artery (in Alcock's canal)
Tuberosity of ischium
Levator ani
Obturator fascia (parietal pelvic fascia)
Fig. 202. — Inner aspect ot the lateral and hinder walls of the Pelvis, showing
the Parietal Pelvic Fascia, the White Line or Arcus Tendineus, and the
Attachment of the Visceral Pelvic Fascia.
and close the great sacro-sciatic foramen, and then to turn
inwards at an angle to reach the structures on the anterior
aspect of the sacrum, or, in other words, to form the fascia of
the pyriformis muscle.
From the close relation which this lateral piece of the
parietal pelvic fascia presents to the obturator internus
528 ABDOMEN
muscle — covering it and having its extent very nearly
determined by the area occupied by the muscle — it is very
commonly called the obturator fascia.
We have previously seen that the parietal pelvic fascia
gives off from its inner surface a layer called the visceral layer,
which proceeds inwards towards the viscera, and acts as a
partition between the pelvis and the perineum. The line
along which this takes origin is generally known under the
name of the white line. If the bladder be pulled well over
from the inner wall of the pelvis, it will be noticed that the
fascia is specially thickened along this line by a band which
stretches in an arcuate manner from the back of the pubis to
the spine of the ischium. This band, which in certain cases
is not fully incorporated with the parietal pelvic fascia, is
termed the arcus tendineus.
Above the arcus tendineus the parietal pelvic fascia is
in relation to the pelvic cavity, and its inner surface is clothed
by peritoneum ; below the arcus, the parietal pelvic fascia
belongs to the perineum, and forms the outer wall of the
ischio-rectal fossa, where its inner surface is in relation to the
fat which fills up this space. About an inch and a half
above the tuberosity of the ischium, the internal pudic vessels
and nerves pass forwards in a tube formed by this fascia
(p. 329), which receives the name of Alcock's canal.
The student has now examined the parietal pelvic fascia
posteriorly and laterally. He must next consider its disposition
in front of the pelvis — i.e., opposite the pubic arch. He
must not suppose, because it has an attachment to the side of
the pubic arch, that it stops there. It is continued onwards
behind the compressor urethrae muscle, across the pubic arch,
and in this situation it is generally known as the superior or
deep layer of the triangular ligament (Fig. 202). The urethra,
on its way to the surface of the body, passes through this
layer, and here the fascia sweeps backwards between the
anterior margins of the two levatores ani muscles and joins
the visceral layer (Fig. 203), where the latter forms the sheath
of the prostate. Inferiorly, it is attached to the base of the
triangular ligament, which, as we have seen, is on the same
morphological plane as the bone; consequently this attachment
is quite in keeping with the attachment of the fascia farther back,
to the tuberosity of the ischium, and to the sciatic ligaments.
Visceral Layer of the Pelvic Fascia. — The visceral layer
PELVIS
529
of pelvic fascia is an aponeurotic sheet, which is placed upon
the upper aspect of the pelvic diaphragm and forms a fascial
partition between the pelvic cavity above and the perineum
below. For the most part it springs from the parietal pelvic
fascia. Laterally it arises from the white line or arcus
tendineus ; in front, however, it is fixed to bone and is
directly attached to the posterior aspect of the pubic bones
about three-quarters of an inch above the attachment of the
Bladder
Pelvic fascia
Obturator
internus
Prostate
Levator ani
Pubic arch -\r%
Constrictor urethra? "VfjMg
Triangular ligament \ 'Wy
(superficial layer) "^y7"
Crus penis
Erector penis
Superficial perineal \£-« ®
vessels and nerves
Fascia of Colles
Visceral pelvic
fascia
Pelvic fascia
Sheath of
prostate
Anal fascia
.Parietal pelvic
fascia
Obturator
membrane
Triangular liga-
ment (deep layer)
Pudic vessels and
nerve
Crus penis covered by
erector penis
Ejaculator urinae covering
the bulb of penis
Fig. 203. — Vertical section through the Bladder, Prostate, and Pubic Arch
to show the arrangement of the Pelvic Fascia : schematic. The pelvic
fascia is depicted in red.
parietal layer. From the surface of the pubic bone between
these layers of fascia the anterior fibres of the levator ani
muscle arise on each side of the symphysis.
From these attachments the visceral pelvic fascia stretches
across the pelvis, and its relations are rendered intricate by
the viscera which it encounters.
Traced inwards from the white line or arcus tendineus, it
reaches the viscera in the neighbourhood of the interval
between the bladder and the prostate (vesico- prostatic
junction) and the outer margin of the seminal vesicle. From
vol. 1 — 34
53o
ABDOMEN
this region it sends downwards a strong layer which gives a
dense insheathment to the prostate, whilst above that level it
contributes an investment to the seminal vesicle and terminal
part of the vas deferens, and then stretches across the
middle line in the interval between the base of the bladder
and the rectum as a thick layer termed the recto-vesical fascia.
When the bladder is empty the recto-vesical fascia, as it
Visceral pelvic fascia
Recto-vesical fascia
Seminal vesicle
Bladder >
■ Visceral pelvic fascia (pubo- \
prostatic ligament)
Bladder
Symphysis pubis
Corpu
cavernosum-
Rectal fascia
Prostatic sheath
Urethra
Bulb of penis
Triangular ligament (deep layer) Triangular ligament (superficial layer)
Fig. 204. — Diagram of the Pelvic Fascia as seen in a mesial section of the
Pelvis. Pelvic fascia represented in red.
extends between the seminal vesicles, presents a free edge
within the sacro-genital fold of peritoneum.
The bladder is thus clothed on its basal aspect by the
recto-vesical fascia containing in its midst the seminal vesicles
and the terminal portions of the vasa deferentia ; but a much
finer layer, termed the vesical layer, is carried upwards and
forwards over the bladder from the visceral pelvic fascia and
gives to this viscus a delicate sheath. As this investment is
traced over the bladder, it becomes so attenuated that it is
PELVIS 531
difficult or even impossible to differentiate it from the sub-
jacent coats. The term lateral true ligament of the bladder
is sometimes used to denote the vesical layer of the visceral
pelvic fascia as it turns upwards on each side from the base
of the prostate on to the bladder.
The sheath of the prostate is a thick-walled fascial compart-
ment within which the prostate is lodged. At the apex or
lower pointed part of this organ the urethra emerges and
immediately pierces the deep layer of the triangular ligament
(parietal pelvic fascia). The margins of the aperture in the
ligament through which it passes are reflected upwards and
become continuous with the prostatic sheath — thus establish-
ing at this point a direct continuity between the parietal and
visceral layers of the pelvic fascia.
The arrangement of the visceral pelvic fascia in the front
of the pelvis should next be studied. As already mentioned,
the visceral layer has a direct attachment to the posterior
aspect of the body of the pubic bone, three-quarters of an
inch above the lower border of the symphysis and above the
origin from bone of the anterior fibres of the levator ani and
the attachment of the parietal pelvic fascia. Draw the apex
of the bladder backwards and look down between this viscus
and the pubic bones. The visceral pelvic fascia will be seen
to pass backwards on either side of the mesial plane in the
form of a strong, rounded, and cord-like band which joins the
anterior wall of the prostatic sheath a short distance below
the vesico-prostatic junction. These bands are the anterior
true ligaments of the bladder, or, if they are looked at merely
in their relations to the pubis and the prostate, they are called
the pubo-prostatic ligaments. Between the bands there is a
very evident interval or recess in the mesial plane, so deep, in
some cases, that the tip of the little finger can be introduced
into it. The sheath of the prostate is not deficient at the
bottom of this recess. A layer of fascia is prolonged from one
side to the other, and hides from view the dorsal vein of the
penis and prostatic plexus of veins which are prolonged
upwards in its substance.
The part of the visceral pelvic fascia which lies behind the
bladder and prostate clothes the upper surface of the levator
ani muscle and becomes intimately related to the rectum.
As low down as the prostate the rectum lies above the visceral
layer of the pelvic fascia, but having reached that level it
532
ABDOMEN
bends backwards and pushes its way through this fascial
septum as it lies upon the levator ani in order that it may
reach the surface at the anus. This terminal part of the gut
is called the anal canal, and as it passes through the visceral
pelvic fascia it carries down on its walls a sheath or invest-
ment termed the rectal fascia. From this it will be seen that
whilst the urethra to reach the surface has to pierce both the
visceral and parietal layers of pelvic fascia, the rectum has
merely to pass through the visceral fascia.
From what has been said, it will be seen that the strong
Fascia iliaca
Peritoneum
Obturator internus---
Levator ani clothed
on inner side by rectal
fascia and on outer —
side by anal fascia
Alcock's canal, con- -
taining pudic vessels
and nerve
w
Bladder
Recto-vesical
fascia
Anal canal
Fig. 205. — Diagram of the Pelvic Fascia. The pelvis is divided in a coronal
plane and the pelvic fascia is represented in red.
and dense portions of the visceral pelvic fascia, viz., the recto-
vesical fascia, including in its substance the seminal vesicles
and the terminal parts of the vasa deferentia, and the sheath
of the prostate enclosing that organ (Fig. 204, p. 530) form
a partition which separates a front compartment for the bladder
from a posterior compartment for the rectum. Within these
pelvic compartments the bladder and the rectum, as they
become filled and emptied, can expand and contract with the
greatest degree of freedom. The prostate with the neck of
the bladder, and also to a less extent the seminal vesicles, are,
on the other hand, firmly fixed in position.
In a recent suggestive paper on the pelvic fascia Professor Paterson
describes the posterior compartment of the pelvic cavity and gives it the
name of the rectal channel.
PELVIS 533
Anal Fascia. — It is necessary, before leaving the pelvic
fascia, to take notice of a layer which has already been
studied in connection with the perineum — viz., the anal fascia.
This is a thin and delicate aponeurosis which covers the
perineal or lower surface of the levator ani, and which is con-
nected with the pelvic fascia along the white line (Fig. 205).
In consequence of this attachment, it is usually described as
a layer of the pelvic fascia. The levator ani is thus enclosed
between two aponeurotic lamellae — viz., the visceral pelvic
fascia and the rectal fascia above, and the anal fascia below.
Relation of Blood-Vessels and Nerves to the Pelvic Fascia.
— The blood-vessels of the pelvis are placed on the peritoneal
aspect of the fascia. It follows, therefore, that the parietal
branches of the internal iliac artery, in passing out from the
pelvis, pierce the membrane, and they always carry with them
a prolongation from it which blends with their sheaths.
There is an exception to this rule — viz., the obturator artery.
It has been observed to pass over the upper border of the
parietal pelvic fascia. The nerves, on the other hand, lie
outside or behind the fascia, and do not require to pierce it in
emerging from the pelvis. This difference in the relation of
the nerves and blood-vessels can be well studied by looking
at the fascia as it passes over the great sacro-sciatic foramen.
The arrangement of the pelvic blood-vessels with reference to the
lining fascia is a matter of some practical interest. The margins of
the apertures in the fascia through which the vessels 'pass are usually
strengthened by some encircling fibres. Sciatic hernia consists in the
escape of a portion of gut through the sciatic notch. It makes its way
through the parietal pelvic fascia by means of one of these apertures.
It may be placed above or below the pyriformis muscle. In the former
case, it escapes through the aperture of the gluteal artery ; in the latter
case, it forces its way through the aperture of the sciatic or internal pudic
artery.
A hernia may also occur through the thyroid foramen (obturator
hernia). In this case, the gut follows the obturator artery over the
upper border of the parietal pelvic fascia through the canal that is formed
between this and the under surface of the pubic bone.
Dissection. — The right innominate bone should now be removed,
in order that a side view of the pelvic viscera may be obtained. The
first step to take is to divide the visceral layer of the pelvic fascia from
behind forwards, about half an inch from the white line. Next, saw-
through the pubic bone, half an inch external to the symphysis, and
divide the great sacro-sciatic ligament close to the sacrum. The further
separation of the bone should be effected at the sacro-iliac articulation by
means of the saw.
In connection with the detached innominate bone, a good view may
be obtained of the fascial origin of the levator ani (Fig. 202, p. 527),
I— 34 a
534
ABDOMEN
and also of the origin of the obturator interims. It is better, however,
to defer the description of these muscles until the viscera are removed.
The dissector should, in the next place, turn his attention to that
portion of the visceral layer of the pelvic fascia which has been left
attached to the viscera. Follow it as far as possible in its reflections
upon them, but preserve intact the sheath of the prostate. "When its
connections have been recognised, remove what remains of the fascia
on the right side, and clean the viscera, taking care not to injure the
Appendix vermiformis
Superior haemorrhoidal vessels
Root of pelvic
mesocolon
Lower end of
pelvic colon
Spermatic vessel
Genito-crural
nerve
External iliac
vessels
Obturator nerve
Obliterated hyp<
gastric artery
Obturator vessel:
Ureter
Pelvic plexus of
nerves
Rectum
Obliterated
hypogastric
artery
Obt. vessels
and nerve
Ureter
Pelvic plexus of nerves
and haemorrhoidal veins
Levator am
Anal canal
External sphincter
Fig. 206. — Dissection of the Rectum from the front in a specimen hardened
by formalin injection. The front wall of the pelvis has been removed, and
the bladder, prostate, and seminal vesicles taken away.
blood-vessels and nerves which supply them. If the viscera have not been
previously hardened in situ by formalin the dissection may be facilitated
if the rectum be moderately stuffed with tow and the bladder partially
inflated with air. In the case of the rectum, first cleanse it thoroughly
by allowing water from the tap to run freely through it, and in the case
of the bladder, pass a staff into it through the urethra, and, having placed
a ligature around the penis, introduce the air through a blow-pipe thrust
into one of the ureters.
When the vesical layer of fascia is divided, a plexus of large veins
will be discovered upon the bladder. These veins ramify over the entire
organ, but are especially numerous in the angle between the bladder and
PELVIS 535
the base of the prostate. These veins constitute what is termed the
vesical plexus.
The vesiculse seminales must be carefully defined, and the obliterated
hypogastric artery and the vas deferens traced to the points where they end.
Pelvic Colon. — As already seen, the pelvic colon (p. 429)
forms a long loop of large intestine completely invested by
peritoneum and attached to the pelvic wall by an extensive
mesentery termed the pelvic meso-colon. It occupies as a rule
the back part of the pelvic cavity ; it rests upon the bladder
and rectum, and lies in the peritoneal fossae on either side of
these viscera.
Rectum (intestinum rectum). — The rectum proper is a
dilated portion of the great intestine, which extends from the
termination of the pelvic colon opposite the third sacral
vertebra to a point about one and a half inches beyond the
tip of the coccyx. Here, at the apex of the prostate, it bends
abruptly backwards, passes through the pelvic floor, and
becomes continuous with the anal canal. The rectum is
about five inches long.
For the greater part of its extent the rectum is adapted to
the anterior surface of the sacrum and coccyx, and con-
sequently presents a curve, the concavity of which is directed
forwards. Beyond the coccyx, the lower inch and a half of
the rectum rests upon the back part of the pelvic floor, formed
by the union of the twTo levatores ani muscles. This portion
of the rectum is also supported behind by the ano-coccygeal
body — a dense mass of tissue, partly muscular and partly
fibrous, which fills up the interval between the coccyx and
the anus.
The relations which the peritoneum presents to the rectum
are of considerable importance. The gut is clothed in its upper
third both in front and on the sides, but the posterior surface
is bare ; the peritoneum now passes away from the sides of the
gut, so that its middle third is merely covered in front ; and
finally about one inch above the base of the prostate it quits
the rectum altogether, and is reflected on to the vasa deferentia,
and the seminal vesicles as they lie in relation to the base of
the bladder. This reflection forms the bottom of the recto-
vesical or recto-genital pouch of peritoneum. The lower third
of the rectum is thus altogether devoid of peritoneal investment.
Below the recto-vesical or recto-genital reflection of
peritoneum, the anterior surface of the rectum is in relation
536
ABDOMEN
to the base of the bladder, and the posterior surface of the
prostate ; whilst interposed between the bladder and the gut
there are on each side the seminal vesicle and the vas
deferens. It must be borne in mind, however, that the strong
recto-vesical layer of the pelvic fascia extends across the pelvis
between the gut and these viscera.
Symphysis pubis
Opening of ureter
. . N
Ureter piercing
wall of bladdeT
ninal vesicle
Vas
deferen
Position of prostate v^^^Wf^ns.
, . x fV-.Vw .?'.■:.•■; KM£,
1_ rethral opening x^f^V. £ 1j— SS»£&>
1 rigone <s^r ^"^W~*~— -Sfc, _^ -ft' -
Bladder
Obturator foramen
/
Obturator vessi
and nerve
Ureter
Inferior vesit
middle hsemi
rhoidal arter
a ^ Pelvic
Branches of superior
hsemorrhoidal artery
Branches of superior
haemorrhoidal artery
Terminal portion
of pelvic colon
Fig. 207. — Oblique Section from above downwards and forwards through the
Pelvis. The peritoneum has been removed so as to expose the viscera
and the parietal pelvic fascia clothing the pelvic wall.
On either side of the upper part of the rectum is the para-
rectal fossa of peritoneum on the postero-lateral wall of the
pelvis, whilst lower down the gut receives support on its
lateral aspect from the levator ani muscle (Fig. 208).
Flexures of the Rectum. — The rectum does not take a
straight course along the back wall and floor of the pelvis.
PELVIS
537
It presents three abrupt lateral bends or flexures. As a rule
two of these are to the left and one to the right, and the
sharply marked infoldings of the wall of the gut on the
Rectum
Anus
3rd sacral
vertebra
4th sacral
vertebra (cut
Pyriformis
(cut)
Lateral
flexure of
rectum
Coccygeus
External
sphincter
Fig. 208. — Dissection of the Rectum from behind. The sacrum below the
4th sacral vertebra and also the coccyx have been removed. Portions
of the levatores ani, coccygei, and external sphincter have also been
taken away. (Birmingham.)
side opposite to the flexures are the cause of the rectal valves
in the interior of the rectum. The flexures are best marked
when the gut is distended, but even when it is empty they arc
as a rule quite apparent. The flexures of the rectum can
538 ABDOMEN
only be satisfactorily studied in a subject which has been
hardened by formalin.
Lying, as it does, between the bladder and prostate in front, and
the concavity of the sacrum and coccyx behind, the rectum when empty
and collapsed has its anterior wall pressed against its posterior wall. In
this condition, therefore, its lumen appears in transverse section in the
form of a transverse slit. Behind the apex of the prostate, at the point
where the gut bends so as to enter upon its third stage, the anterior wall
in the distended condition of the rectum sometimes shows a slight bulging
or cul-de-sac which gains a lower level than the prostate.
Anal Canal. — This is the narrow slit-like passage which
leads from the rectum to the anus. Except during the
passage of faeces it is always tightly closed by the application
of its lateral walls to each other. In coronal sections of the
pelvis, therefore, it appears in the form of a longitudinal slit
(Fig. 209). It is very different in its surroundings and func-
tions from the other parts of the rectum, and may appropriately
be distinguished by a special name (Symington).
The anal canal begins at the apex of the prostate and pro-
ceeds downwards and backwards to the anal orifice. In
length it measures from one to one and a half inches. It is
totally destitute of peritoneum, but it is supported and clothed
by a prolongation from the rectal layer of the pelvic fascia. It
is closely surrounded by strong muscles which keep constant
guard over it, and only allow its lateral walls to separate from
each other during defalcation. Thus, the internal sphincter
encircles it in very nearly its whole length ; the external
sphincter surrounds the anal orifice and lower part of the
wall ; whilst above this, at the commencement of the canal,
the thick margins of the levatores ani grasp the canal laterally
and pinch in its walls. The membranous portion of the
urethra and the bulb of the penis are placed in front of the
anal canal, but, owing to the backward inclination of the gut,
these are not in contact with it, but are separated from it
by an angular interval. Behind the anal canal is the ano-
coccygeal body (Symington).
The staff, which has, been introduced into the bladder, being held in
the middle line, the student should pass the forefinger of the right
hand into the rectum, and endeavour to distinguish by touch the parts
in relation to the anterior aspect of the gut. Passing beyond the bulb,
the staff, as it lies in the membranous part of the urethra, will be felt
very distinctly ; next, the prostate will be encountered ; and, imme-
diately behind this, the finger, provided it is carried upwards exactly in
the middle line, will rest upon the vasa deferentia and the extremely narrow
triangular surface of the base of the bladder, which is in contact with
PELVIS
539
the rectum — the rectovesical layer of pelvic fascia alone intervening. To
the outer side of the vas deferens the seminal vesicle can be distinguished
through the wall of the rectum.
Bladder (vesica urinaria). — This is a hollow viscus, with
strong muscular walls, which acts as a temporary reservoir
for the urine, before it is emitted from the body by the process
fe - : .
^Vr^^S.-V.
Anal canal (note the,
apposition of its lateral
walls)
Sphincter ani internus—
Sphincter ani externu
f
m v
I v\V
' k
Fig. 209. — Coronal section through the whole length of the
Anal Canal. (Symington.)
B. Bladder.
Y.D. Vas deferens.
S.V. Seminal vesicle.
R. Terminal portion of the rectum
(note the apposition of its an-
terior and posterior walls).
of micturition. As will be readily understood, its form, and
in a great measure its position and relations, are influenced
by the quantity of fluid which it contains.
The different forms which the bladder assumes under its constantly
changing conditions render its description a matter of serious difficulty.
As a rule it is found in the dissecting-room with contracted walls and
empty. For this reason, and also because our information regarding the
54°
ABDOMEN
empty bladder is more exact, we shall study in the first place the form
which it presents when in this condition, and then refer briefly to the
changes it undergoes as it becomes filled with urine. In what follows
the description which has been recently given of the empty bladder by
Professor Dixon is closely followed.
H@d§ ^ Ureter
Superior surface
Vas-V
Seminal
vesicle
rachus
Infero-lateral surface
Prostate
Membranous urethra
APEX
Fig. 210. — Bladder hardened in si hi viewed from the right side. It
contained a very small quantity of fluid. (A. F. Dixon. )
The empty bladder lies completely within the cavity of the
pelvis, and it presents a superior surface, an inferior surface,
a base, and an apex. Its long axis, which is directed from
before backwards, or, in other words, from apex to base, is
horizontal. The superior surface,
wmich looks upwards and sup-
ports some coils of small intes-
tine and, as a rule, a
portion of the pelvic colon,
is slightly convex and
triangular in outline. It
is completely covered by
peritoneum, and is
bounded by three
borders, viz., two
lateral and a pos-
terior. The lateral
borders converge
in front and meet
at the apex. From
the apex, which is placed in relation to the upper part
of the symphysis pubis, a strong fibrous cord, called the
urachus, proceeds upwards on the posterior aspect of the
anterior abdominal wall to the umbilicus. The urachus
URETER
URETER
Fig. 2ii. — Diagram of the Under Surface of the
Empty Bladder. (After A. F. Dixon.)
PELVIS 541
represents the obliterated intra-abdominal part of the allan-
toic sac of the developing embryo. Posteriorly the lateral
borders of the empty bladder meet the posterior border, and on
each side the point of junction is marked by a very distinct
angle termed the lateral angle. This angle is rendered all the
more conspicuous from the fact that it is here that the ureter
joins the bladder. The lateral border of the empty bladder
is in relation to the side-wall of the pelvis along a line con-
siderably below the level of the vas deferens and obliterated
hypogastric artery.
The basal surface of the empty bladder looks backwards
Ureter
Vas ^ ' T in
Seminal ^^\\ Urachus
vesicle jP JSft^SJjSS 1 rs-^^^Si^V
Prostate ; Infero-lateral surface
" I 'ifs Membranous urethra
Fig. 212. — Bladder hardened in situ viewed from the right side. It
contained a slightly larger amount of fluid than the specimen depicted in
Fig. 210. (A. F. Dixon.)
towards the rectum, but is separated from it by the inter-
vening vasa deferentia and seminal vesicles. The recto-vesical
layer of pelvic fascia also passes across between the base
of the bladder and the rectum.
The urethral orifice, by which the urine leaves the bladder,
is placed on the inferior aspect of the viscus and occupies the
most dependent position. It is surrounded by the base of
the prostate, which presents a structural continuity with the
bladder wall. The term neck is frequently applied to this
region of the bladder. The i?iferior surface of the bladder,
in front of the prostate, presents an obscure subdivision into
two lateral parts, which may be called the infero-lateral areas,
by a rounded border which runs forward from the urethral
orifice to the apex. These areas are separated from the
542 ABDOMEN
superior surface by the lateral borders of the organ and from
the basal surface by two borders which extend from the lateral
angles or points where the ureters join the bladder to the
urethral opening.
The empty bladder when hardened in situ therefore presents the form
of an inverted tetrahedron, the base of which is represented by the
superior surface of the organ, the apex by the urethral orifice and the three
surfaces by the basal surface and the two infero-lateral areas.
Each of the infero-lateral areas is supported in front by the
symphysis pubis and the body of the pubic bone ; behind
this, by the retro-pubic pad of fat ; and still farther back by
the fascia covering the obturator internus and the levator ani
muscles. The retro-pubic pad is a small wedge-shaped mass
of soft, pliable, fatty areolar tissue which occupies a space
bounded above by the bladder, behind by the anterior true
ligaments of the bladder, and below by the pubic bones. It
adapts itself to the changing conditions of the bladder.
Changes in the form of the Bladder as it becomes filled with Urine. —
The neck of the bladder or the urethral orifice is firmly fixed in position.
This is chiefly due to the manner in which it is grasped and held in place
by the base of the prostate and also to the connections which are established
between it and the visceral layer of the pelvic fascia. The prostate also
is securely anchored in its place by the strong sheath which it derives
from the pelvic fascia. As the bladder becomes filled the urethral
orifice therefore suffers very little change in position, and it is only in
cases of excessive distension that any marked alteration in its level becomes
manifest. Under such circumstances the urethral orifice sinks to a certain
extent in the pelvic cavity.
As the bladder fills by the entrance of urine into it through the ureters,
the superior wall is raised from the inferior and basal walls. All its
surfaces increase in area, and the borders which in the empty bladder
intervene between them become rounded off and finally obliterated. The
organ thus becomes ovoid in form, and the walls, which are thick and firm
in the contracted state, become comparatively thin. The apex appears
above the symphysis pubis, and as distension goes on the organ rises
higher and higher into the hypogastric region, until a considerable extent
of its wall becomes applied to the abdominal wall above the pubis.
The lateral surfaces of the distending bladder encroach upon the paravesical
fossae so as to gradually obliterate them, and thus come into contact on
each side with a greater extent of the lateral wall of the pelvis.
When the bladder is excessively distended it assumes a spherical form,
or perhaps an ovoid form with the enlarged end at the apex (Fig. 214).
In the latter case the long axis is no longer horizontal, but oblique, being
directed from above downwards and backwards.
When the urine is ejected from the bladder the superior wall descends
until it becomes approximated to the inferior wall and the basal wall.
The viscus, therefore, becomes flattened from above downwards, and
comes to lie entirely within the cavity of the true pelvis. When such a
bladder is examined in a mesial section of the pelvis, and in a subject
PELVIS
543
from whom the urine has been expelled shortly before death, the walls
of the bladder are thick and firm, and the lumen of the viscus may be
reduced to a mere slit. The part of the lumen which lies behind the
urethral opening, formed by the approximation of the superior wall with
the basal wall, is spoken of as the posterior limb, whilst that part formed
by the approximation of the superior and inferior walls of the viscus in
front of the urethral opening is called the anterior limb of the cavity.
The anterior limb of the cavity is long and nearly horizontal. The
Rectus
abdominis
yramidalis
etro-pubic
Corpus
avernosum ///
Vas
Prostate
Sphincter
ani externus
Sphincter
ani internus
Bulb
Sphincter
ani externus
Ejaculator urina;
Fig. 213. — Mesial section through the Pelvis of an Adult
Male. The bladder is nearly empty, and the urethra is
divided along its whole length.
R. Rectum.
S. Symphysis.
B. Bladder.
posterior limb is short, and sometimes barely recognisable ; further,
it is oblique or perhaps vertical, and joins the anterior limb at the
urethral opening at an angle. Viewed, therefore, in mesial section,
the lumen of the perfectly empty bladder usually forms a Y-shaped
figure with the lumen of the upper part of the urethra.
In other cases the empty bladder is firm and rounded, and when
divided in the mesial plane its cavity is seen to present only the one
limb or slit continuous with the lumen of the urethra.
Relation of the Peritoneum to the Bladder. — In the empty
bladder the peritoneum merely covers the superior surface.
544
ABDOMEN
The other surfaces of the bladder are uncovered, although it
should be remembered that the membrane passes downwards
to some extent behind the basal surface, but in this situation
it is separated from it by the seminal vesicles and the vasa
deferentia.
When the bladder fills and the organ rises into the hypo-
gastric region it is important to note that the peritoneal
Peritone
reflectior
Peritoneal \\ '
reflection
Retro-pubic
pad of fat
Urethra
Fig. 214. — Mesial section through a Male Pelvis, in which the
Bladder is greatly distended.
B. Bladder. S. Symphysis pubis.
R. Rectum. Sa. Sacrum.
reflection from the apex is raised along with the organ, so that
now there is a considerable area of the bladder wall, below
the urachus, applied directly to the anterior abdominal wall
without the intervention of peritoneum.
Laterally also the line of peritoneal reflection is raised
until it may appear to leave the lateral surface of the bladder
along the line of the vas deferens as this passes backwards
along the side wall of the pelvis or even as high as the level of
the obliterated hypogastric artery.
PELVIS
545
Posteriorly the sacro-genital fold appears to open out and
become more or less completely obliterated, so as to provide a
covering for the expanding basal portion of the bladder. It
would appear that the level of the reflection of peritoneum
which forms the bottom of the recto-vesical or recto-genital
pouch does not undergo change with the distension of the
bladder. When the rectum becomes distended the recto-
genital reflection assumes a higher level, but this is not due
to any change in the position of the peritoneum in reference
to the bladder, but to the entire bladder with the reflection
being pushed upwards and forwards by the loaded gut.
In the new-born infant the form and position of the bladder are very
different from what are found in the adult. It is more or less pyriform
in shape, the narrow end gradually passing into the urethra, and there
Reflection of peri-
toneum from
bladder to anterior
wall of abdomen _
Bladder
Recto-vesical
peritoneal
reflection
Bulb of the penis
Sphincter ani
externus
Sphincter ani
externus
Fig. 215. — Mesial section through Pelvis of a newly-born full-
time Male Infant.
R. Rectum.
Sa. Sacrum.
S. Symphysis pubis.
is little or no appearance of a basal portion (Fig. 215). Further, it is
placed very much higher. The urethral orifice is situated at the level
of the upper border of the symphysis pubis, and the anterior surface
of the organ, entirely uncovered by peritoneum, is in contact with the
lower two-thirds of that part of the posterior surface of the anterior ab-
dominal wall which lies between the symphysis pubis and the umbilicus
(Symington). As growth goes on, " the urethral orifice sinks rapidly
from the period of birth up to the beginning of the fourth year, and
more slowly from that period up to the beginning of the ninth year ; it
now remains stationary until the commencement of puberty, and then it
sinks slowly until it ultimately attains its normal adult position " (Disse).
One other point may be noted in connection with the infantile bladder,
viz., the recto-vesical reflection of peritoneum corresponds to the base of
the prostate.
Ureters. — Within the pelvis the ureter of each side pro-
ceeds under cover of the peritoneum towards the base of the
bladder. It first passes downwards and slightly forwards on
the lateral wall of the pelvis. In this part of its course it lies
vol. 1 — 35
546 ABDOMEN
in front of the internal iliac artery and crosses the obturator
vessels and nerve and also the obliterated hypogastric artery.
Then, curving inwards, it is crossed by the vas deferens and
reaches the bladder in front of the upper end of the seminal
vesicle. Here, at a point about two inches from its fellow of
the opposite side and about one and a half inches from the
base of the prostate, it pierces the bladder-wall. In its course
over the side wall of the pelvis, and more especially as it
curves inwards to the bladder (when that viscus is empty), it
raises the peritoneum, which covers it in the form of a ridge
or low fold.
Prostate (prostata). — This is a solid body, partly glandular
and partly muscular, which embraces the urethral orifice of the
bladder and surrounds the first part of the urethra.
In shape, it is conical, and somewhat resembles a Spanish
chestnut — its base being directed upwards, and its apex
downwards. In size, it is variable ; but its average dimensions
are commonly stated to be about one inch and a quarter from
base to apex, and one inch and a half from side to side at its
broadest part. The prostate rests upon the anterior aspect of
the lower part of the rectum. It is about one inch and a
half distant from the anus, whilst its anterior surface lies three-
quarters of an inch behind the lower part of the symphysis
pubis.
As already mentioned, the prostate is lodged within a dense
aponeurotic sheath derived from the visceral pelvic fascia.
This sheath is firmly anchored in place within the pelvis not
only by the pubo-prostatic ligaments but also at the apex of
the prostate by the continuity which is established, around the
emerging urethra, between the sheath and the deep layer of
the triangular ligament. These connections prevent the
prostate from altering its position in response to the continual
changes which occur in the state of distension of the bladder.
It is a matter of some practical importance to note that the
prostate lies somewhat loosely within its sheath.. Only in the
middle line in front and at the apex where the urethra
emerges from the substance of the organ is there any degree
of adhesion between the prostate and its fascial envelope
(Stoney).
On the anterior aspect of the prostate there is a network
of thin-walled veins, the prostatic plexus, into which the
dorsal vein of the penis pours its blood. At a higher level
PELVIS 547
this venous plexus becomes continuous with the large veins
which are lodged in the groove between the base of the
prostate and the bladder. The prostatic veins are embedded
in the deeper part of the fascial sheath — a matter of importance
in connection with the operation which is now so frequently
practised for the removal of the prostate.
The prostate has an immediate investment or envelope within the
sheath derived from the pelvic fascia. This is termed the capsule so as to
distinguish it from the sheath, and it is formed of layers of fibro-muscular
tissue continuous, and more or less incorporated with, the stroma of the
prostate. The capsule varies much in thickness, being in some cases
exceedingly thin whilst in others it is so thick that it forms a distinct cortex
around the gland.
The prostate presents for examination a base or superior
surface, an apex, a posterior, an anterior, and two lateral
surfaces. The base looks upwards, surrounds the urethral
orifice on the under surface of the bladder, and over the
greater part of its extent is structurally united to the bladder-
wall. Around the greater part of its circumference, however,
it is separated from the bladder superficially by a broad groove
which is filled with large thin-walled veins. The apex is the
dependent pointed part of the organ. It looks downwards
and abuts against the deep layer of the triangular ligament.
The posterior surface is a flat, somewhat triangular area, which
rests on the anterior aspect of the rectum. The anterior
surface takes the form of a prominent and rounded mesial
border which intervenes between the.two lateral surfaces, and
from the lower part of which, immediately above the apex, the
urethra emerges from the substance of the gland (Dixon).
This border occupies the interval between the two thick
anterior margins of the levatores ani muscles. The lateral
surfaces are full and rounded, and are supported on each side
by the corresponding levator ani muscle.
When the seminal vesicles and the vasa deferentia are
detached from the bladder and thrown backwards, it will be
seen that the slender common ejaculatory ducts pierce the
base of the prostate close to the upper part of its posterior
surface. Within the substance of the organ these delicate
ducts pass downwards with a slight inclination inwards, and
finally open into the prostatic part of the urethra. The
portion of prostatic substance between the ducts and the
bladder- wall is often called the middle lobe. The remainder of
the organ is generally spoken of as consisting of two lateral
i — 35 a
543
ABDOMEN
lobes, although there is no superficial or deep demarcation
between them.
Vesiculse Seminales. — These are two sacculated receptacles
for the semen, each about two inches in length, which inter-
vene between the base of the bladder and the rectum.
Conical or somewhat pyriform in shape, each seminal vesicle
presents a narrow inferior end in close proximity to the base
of the prostate, and an expanded or blunt superior end in
relation to the recto-vesical pouch of peritoneum and the
entrance of the ureter. Inferiorly, they are near to each
other and the mesial plane, but they diverge widely as they
'Ureter
Seminal
vesicle
Membranous urethra
Fig. 216. — Basal aspect of Bladder, Seminal Vesicles, and Prostate
hardened by formalin injection.
proceed upwards and outwards, so that posteriorly they] are
separated by a wide interval. The vas deferens lies along
the inner side of each, and both are enclosed within a dense
sheath derived from the recto-vesical layer of visceral pelvic
fascia.
Each vesicula seminalis is in reality a closed tube, five or
six inches long, coiled upon itself and held in its present form
by a dense areolar tissue. When unravelled, several diverti-
cula will be observed to proceed from the main tube. The
narrow anterior end of the vesicle joins the vas deferens at
an acute angle to form the common ejaculatory duct.
Vas Deferens (ductus deferens). — The vas deferens, or
duct of the testicle, has already been traced to the internal
PELVIS
549
abdominal ring, through which it enters the abdomen.
Separating itself from the other factors of the spermatic
cord, it hooks round the deep epigastric artery, and descends
upon the inner side of the external iliac vessels into the
pelvis. It now runs backwards upon the side wall of the
pelvis, immediately beneath the peritoneum, through which
it is clearly visible, and it crosses in turn the obliterated
hypogastric artery, the obturator nerve, and the ureter.
Immediately beyond the ureter it turns sharply inwards
towards the base of the bladder, comes into relation with the
upper blunt end of the seminal vesicle, and runs downwards
Ureter
Seminal vesicle
Rectun
33 Urethral orifice
— Trigone of bladder
]«J§Je> — Ureter
Vas
Fig. 217. — Horizontal section through the Bladder and Rectum at the
level at which the ureters enter the bladder.
and inwards in close apposition with its upper or inner side.
Finally, on the base of the bladder it approaches close to the
mesial plane, and its fellow of the opposite side, and, bending
on itself, proceeds almost vertically downwards to the base of
the prostate (Fig. 216). The lower part of the vas is much
dilated, tortuous, and sacculated, and is termed the ampulla.
At the base of the prostate the vas narrows greatly and is
joined by the duct of the seminal vesicle, thereby forming
the common ejaculatory duct.
Triangle on the Base of the Bladder. — It is usual to
describe a triangular space on the base of the bladder between
the two vasa deferentia and bounded above by the reflection
of the peritoneum at the bottom of the recto-vesical or recto-
1 — 35 1
55o ABDOMEN
genital pouch. When the pelvic viscera are hardened in situ
by formalin injection, it becomes evident that such a space
can hardly be said to exist owing to the close approximation
of the apullated terminal parts of the vasa deferentia (Fig. 216).
It occasionally happens that in retention of urine it is impossible to pass
a catheter into the bladder to relieve the distension. In these cases it
becomes necessary to puncture the bladder with a trocar and cannula. It
is customary to state that the operation may be performed at two points
without injury to the peritoneum or other important structures — viz., (1) in
the middle line immediately above the pubic symphysis, where, in the
distended condition of the viscus, there is a wide area of bladder-wall
uncovered by peritoneum ; (2) through the rectum and within the limits of
the small triangular space on the base of the bladder. As we have seen,
however, this space can hardly be said to exist, and it is extremely doubtful
if this operation could be performed without wounding the vasa deferentia.
Dissection. — The blood-vessels of the pelvis should now be followed out.
For this purpose it is necessary to remove the stuffing from the rectum and
allow the air to escape from the bladder. The peritoneum upon the left
side and the loose tissue around the vessels must be dissected away.
Accompanying the arteries the dissector should notice numbers of fine
nerve twigs from the pelvic plexus, and from the third and fourth sacral
nerves. Preserve these as far as it is possible to do so. Upon the right
side the blood-vessels are more or less injured, and some of them severed,
by the removal of the innominate bone ; on the left side, however, they
are intact.
Pelvic Blood -Vessels. — The pelvic arteries are the
following : —
1. The internal iliac and its branches (upon each side).
2. The middle sacral 1 .. ., ■ T » >
r~, , , .j , V (in the mesial plane).
3. I he superior hsemorrhoidal J r
Internal Iliac Artery (arteria hypogastrica). — This is a
short, wide vessel, which commences opposite the lumbo-
sacral articulation, at the bifurcation of the common iliac.
It proceeds downwards and backwards into the pelvis, and
ends near the upper part of the great sciatic notch by divid-
ing into an a?iterior and posterior division. In length it
measures about one inch and a half, and its calibre in the
adult is considerably smaller than that of the external iliac.
The impervious hypogastric artery extends forwards from its
extremity.
The internal iliac artery presents the following relations.
As it descends it is separated from the inner aspect of the
psoas by the external iliac vein. It lies between the ureter,
which is in front, and the internal iliac vein, which is behind;
whilst it is covered on its inner or pelvic aspect by the
peritoneum. On the left side the internal iliac artery is
PELVIS
551
intimately related to the pelvic colon ; and on the right side it
presents similar relations to the terminal part of the ileum.
Condition in the Foetus. — Very different is the condition of the internal
iliac artery in the foetus. It is termed the hypogastric artery, and is twice
as large as the external iliac. Instead of terminating at the sciatic notch,
it extends forwards and ascends upon the posterior aspect of the anterior
wall of the abdomen to the umbilical orifice, through which it passes in
company with its fellow of the opposite side and the umbilical vein. Out-
side the abdominal cavity the hypogastric arteries enter the umbilical cord,
and, twining spirally around the umbilical vein, they reach the placenta,
where the impure blood which they carry is brought into relation with the
maternal blood.
After birth, when the umbilical cord is divided and a ligature placed
around it, the hypogastric arteries become filled with clot, which is
gradually absorbed. At the same time the vessels shrivel, and after a few
years they are merely represented by the fibrous cords which we have
examined in the adult. A small portion of this cord, close to the internal
iliac artery, usually remains patent, and from this the superior vesical artery
takes origin.
Obliterated Hypogastric Artery. — Close to its junction
with the internal iliac artery this fibrous cord remains patent,
and from this pervious portion the superior vesical artery
arises. The obliterated vessel proceeds forwards on the side
wall of the pelvis towards the apex of the bladder, and on
the posterior aspect of the anterior abdominal wall it can be
traced beneath the peritoneum to the umbilicus.
Branches of the Internal Iliac. — The branches of this
artery spring from the two divisions into which it divides, and
may be tabulated thus : —
Anterior Division.
Posterior Division.
Parietal.
\ "isceral.
Parietal.
Visceral.
1 . Obturator.
2. Internal
pudic.
3. Sciatic.
c
1. Superior
vesical.
2. Inferior
vesical.
3. Middle
hemor-
rhoidal.
1. Ilio-lumbar.
2. Gluteal.
3. Lateral
sacral.
I
Superior Vesical (arteriae vesicales superiores). — Under this
name are included two or three small twigs which spring
from the pervious part of the obliterated hypogastric artery,
and proceed forwards to the coats of the bladder. They
552 ABDOMEN
supply the apex and the greater part of the body of the
bladder, and from one of them a minute twig, the artery to
the vas deferens (arteria deferentialis), is given to the seminal
duct. Although exceedingly slender, this branch can be
followed along the vas as far as the testicle.
Inferior Vesical (arteria vesicalis inferior). — This artery
runs inwards upon the pelvic aspect of the levator ani. It
ramifies upon the base of the bladder, and sends twigs to the
seminal vesicle, the vas deferens, the terminal part of the
ureter, and the prostate.
The middle hemorrhoidal (arteria haemorrhoidalis media)
very frequently proceeds from the inferior vesical. It is given
to the coats of the rectum, and anastomoses above with the
superior haemorrhoidal branch of the inferior mesenteric, and
below with the inferior haemorrhoidal twigs from the internal
pudic. It likewise supplies twigs to the prostate and the
seminal vesicle.
The obturator artery (arteria obturatoria) proceeds forwards
upon the inner aspect of the pelvic wall to the upper part of
the thyroid foramen. Here it comes into relation with the
nerve of the same name, and both leave the cavity by passing
above the pelvic fascia and below the groove upon the under
surface of the ascending ramus of the pubic bone. Within
the pelvis it lies in the extra-peritoneal fatty tissue, between
the peritoneum and the parietal pelvic fascia ; the obturator
nerve is placed at a higher level, whilst the vein lies below it.
In this part of its course the obturator artery furnishes a
small iliac branch to the parts in the iliac fossa, and a minute
pubic branch, which ramifies upon the back of the pubic
bone and anastomoses with a similar branch from the deep
epigastric artery.
The pudic artery (arteria pudenda interna) is now seen in
the pelvic part of its course. It proceeds downwards upon
the pyriformis muscle and sacral nerves, and, reaching the
lower part of the great sacro-sciatic foramen, it leaves the
pelvis by passing through it. In the gluteal region it appears
between the pyriformis and the superior gemellus.
The sciatic artery (arteria glutaea inferior) can be recognised
from its being the largest of the branches which spring from
the anterior division of the internal iliac, and also from its
generally lying a little behind the pudic. It proceeds down-
wards upon the pyriformis muscle and sacral nerves, and quits
PELVIS 553
the pelvis for the gluteal region through the lower part of the
great sacro-sciatic foramen.
The ilio- lumbar artery (arteria ilio-lumbalis) is directed
upwards, outwards, and backwards behind the obturator nerve,
the external iliac vessels, and the psoas muscle, to the iliac
fossa, where it divides into a lumbar and an iliac branch.
The lumbar branch (ramus lumbalis) runs upwards and ramifies
in the substance of the psoas and quadratus lumborum
muscles, where it anastomoses with the lower lumbar arteries.
It gives off a small spinal branch (ramus spinalis), which enters
the spinal canal through the intervertebral foramen between
the last lumbar vertebra and the sacrum. The iliac branch
(ramus iliacus) breaks up into twigs, which run outwards, some
in the substance of the iliacus muscle, and others between
it and the bone ; of the latter set, one will he observed to
enter the nutrient foramen in the iliac fossa. Reaching the
crest of the ilium, the terminal branches of this vessel
anastomose with the deep circumflex iliac and lumbar
arteries.
The gluteal artery (arteria glutaea superior) is the largest of
the branches of the internal iliac, and may be regarded as the
continuation of its posterior division. It has a very short
course within the pelvis. Passing backwards between the
lumbo-sacral cord and the first sacral nerve, it leaves the pelvis
through the upper part of the great sacro-sciatic foramen,
and appears in the gluteal region in the interval between the
pyriformis and gluteus minimus muscles.
The lateral sacral (arteria sacralis lateralis) is usually
represented by two arteries, which extend downwards upon
the pyriformis muscle and sacral nerves, external to the
anterior sacral foramina and the sympathetic cord. They
furnish twigs to the parts upon which they lie, and branches
which enter the sacral foramina (rami spinales). The latter,
after supplying the membranes and nerve -roots within the
sacral canal, emerge behind, through the posterior sacral
foramina, and there anastomose with branches of the gluteal
artery. The lower of the two lateral sacral arteries inosculates
inferiorly with the middle sacral.
Superior Hemorrhoidal Artery (arteria haemorrhoidalis
superior). — This is the direct continuation into the pelvis of
the inferior mesenteric artery. After crossing the common
iliac artery it enters the root of the pelvic meso-colon and
554 ABDOMEN
descends between its two layers as far as the third piece of
the sacrum. Here it divides into two branches which proceed
downwards on either side of the rectum. These vessels soon
break up into several smaller branches, which range themselves
around the gut and pierce its muscular coat half-way down the
rectum. Within the submucous coat they continue their
course to the anal canal, where it is usual to find one within
each column of Morgagni. Above the anus they anastomose
freely with each other, with the inferior hsemorrhoidal branches
of the internal pudic arteries, and higher up with the middle
haemorrhoidal branches of the internal iliac arteries.
Middle Sacral Artery (arteria sacralis media). — The
middle sacral has already been observed springing from the
posterior aspect of the termination of the abdominal aorta,
between the two common iliac arteries. It descends upon
the bodies of the lower two lumbar vertebrae and under cover
of the left common iliac vein. Reaching the sacrum, it con-
tinues its downward course in the mesial plane till it arrives
at the coccyx. Here it ends by anastomosing with the lateral
sacral arteries, and by sending minute branches to the
coccygeal body. From each side it gives off small twigs,
which ramify upon the anterior aspect of the sacrum and
inosculate with branches of the lateral sacral arteries.
Veins of the Pelvis. — The arrangement of the veins in
the pelvis corresponds in a great measure with that of the
arteries ; still, there are some important points of difference,
viz. : —
t. The dorsal vein of the penis, instead of joining the pudic
vein, proceeds backwards, divides into two, and enters the
prostatic plexus of veins.
2. The ilio- lumbar and the middle sacral veins, as a
general rule, pour their blood into the common iliac veins.
3. The veins around the prostate, bladder, and rectum
are exceedingly large and numerous, and constitute dense
plexuses, which freely communicate with each other. The
prostatic and vesical plexuses have already been noticed. They
are directly continuous, and the blood is drained from them
by the vesical veins. The hemorrhoidal plexus consists of two
parts, viz., one in the submucous coat and the other on the
outer surface of the gut. It is the latter which is seen at
present. From this the blood is drained away by three different
veins — viz., the inferior haemorrhoidal, which carries it to the
PELVIS 555
pudic vein \ the middle hemorrhoidal, which leads it to the
internal iliac vein ; and the superior hemorrhoidal vein, which
is one of the rootlets of the portal vein. The hemorrhoidal
plexus may therefore be regarded as being the link between the
systemic and portal systems of veins. This has an important
bearing upon the production of hemorrhoids, which consist in
a varicose condition of the hemorrhoidal veins. As we have
seen, the portal vein and its tributaries are devoid of valves ;
consequently, anything retarding the flow of blood through the
portal system will react upon the hemorrhoidal plexus, cause
its distension, and predispose to hemorrhoids.
The internal iliac vein (vena hypogastrica) proceeds upwards
behind the artery of the same name, and joins the common
iliac vein. With the exception of the ilio- lumbar vein, it
receives tributaries corresponding to the branches of the
artery.
Lymphatics of the Rectum. — Four or five rectal glands
are disposed in relation to the superior hemorrhoidal vein
and its two main tributaries. Most of the rectal lymphatic
vessels join these and then proceed to the sacral glands on
the front of the sacrum. It should not be forgotten that the
cutaneous lymphatics from around the anus pass to the
inguinal glands.
Dissection. — The diaphragm of the pelvis should next be examined. It
is composed of two muscles upon each side — viz., the levator ani and the
coccygeus. Draw the viscera as far as possible to the right, and remove
what remains of the visceral layer of the pelvic fascia upon the left side.
This will expose the upper surface of the levator ani, the connections of
which can now be studied. In cleaning the coccygeus, be careful not to
injure the fifth sacral nerve and the coccygeal nerve, both of which pierce
it near its insertion.
Levator Ani. — The levator ani is a strong sheet of
muscular fibres, which forms the anterior and greater part
of the pelvic diaphragm. It has a triple origin. The
anterior fibres spring from the back of the body of the pubic
bone between the attachments of the visceral and parietal
layers of pelvic fascia; the posterior fibres arise from the pelvic
surface of the ischial spine ; whilst the intermediate fibres,
constituting the greater part of the muscle, take origin
from the inner surface of the parietal pelvic fascia along a
line which varies in level in different individuals.
The insertion of the levator ani must also be looked at
from three points of view. The anterior fibres proceed down-
556
ABDOMEX
wards upon the lateral aspect of the prostate ; and from the
support which they give to it, they are sometimes spoken of
under the name of levator prostata. Behind the prostate a
certain number of these fibres meet in the mesial plane, with
the corresponding fibres of the opposite side, and are inserted
into the central point of the perineum, but the majority enter
the muscular wall of the anal canal. The inter ?7iediate and
Symphysis pubis
Spine of pubis
Pelvic fascia
/
Central point of/
perineum
T~~ Sphincter ani externus
Fig. 218. — Dissection of the two Levatores Ani. The pelvis is tilted forwards
and the pubic arch has been removed. Both layers of the triangular
ligament, the parts in relation to them, and the pubic origins of the
levatores ani have also been taken away. The portion of bone removed
is indicated by the dotted lines.
largest portion of the muscle slopes downwards, backwards,
and inwards, and gives support to the rectum and bladder.
At the junction of the rectum and the anal canal the muscle
forms a thick collar around the gut, pinches it in and is then
continued down on the side of the anal canal in the interval
between the two sphincter muscles (Fig. 206, p. 534). The
posterior fibres pass backwards and inwards and are inserted
into the median ano-coccygeal raphe behind the rectum, and
also into the side of the lower end of the coccyx. They
PELVIS 557
support the portion of the rectum which extends from the
tip of the coccyx to the anal canal.
The levator ani draws its nerve supply from the fourth
sacral nerve and the inferior hcemorrhoidal nerve.
Coccygeus. — This is a small triangular muscle which lies
behind and upon the same plane as the levator ani —
indeed, their margins are contiguous. It arises by its narrow
end from the pelvic surface of the ischial spine, and from the
parietal pelvic fascia above the spine. Expanding as it passes
inwards, it is inserted into the margin of the lower piece of
the sacrum and the margin and anterior aspect of the coccyx.
It is supplied by twigs from the fourth and fifth sacral nerves.
Pelvic Spinal Nerves. — The anterior primary divisions of
the spinal nerves in the pelvis are six in number, viz., five
sacral and one coccygeal. These should be dissected, and the
various branches which they give off followed to their distribu-
tion, or the point where they quit the pelvis. It is well to
begin by cleaning the lumbo-sacral cord and securing the
upper root of the superior gluteal nerve which springs from its
posterior aspect. The upper four sacral nerves appear through
the anterior sacral foramina ; the fifth sacral nerve comes
forward in the interval between the sacrum and coccyx ;
and the coccygeal a little lower down at the side of the
coccyx. The two latter are very minute, but they can be
easily found by following downwards a twig from the fourth
to the fifth sacral nerve, and another twig which connects
the fifth nerve with the coccygeal.
The first and second sacral nerves are very large, and
almost equal in size; the third sacral nerve is much
smaller than these, and the fourth still smaller than the
third. Each spinal nerve is joined by grey ra?ni communicantes
from the sympathetic ; whilst from the third and also from the
fourth sacral nerve white ra?ni commimicantes pass out to join
the pelvic plexuses from the sympathetic cord.
The first three sacral nerves unite to form the sacral plexus.
This is joined above by the lumbo-sacral cord, and below by a
branch from the fourth sacral nerve.
The fifth sacral nerve and the coccygeal nerve, with the
descending branch of the fourth sacral nerve, unite to form
the sacro-coccy geal plexus.
Sacral Plexus (plexus sacralis). — When the nerves which
enter the sacral plexus are dissected they will be seen to
558
ABDOMEN
-FROM L. IV
SU/TEAL
resolve themselves into two flattened bands — viz., an upper
sciatic and a lower pudendal. The sciatic band is very large,
and is formed by the union of the lumbo-sacral cord with
the first sacral nerve and the greater portion of both the
second and the third sacral nerves. It proceeds downwards
and outwards to the lower part
of the great sacro-sciatic foramen,
and, here much reduced in width
and increased in thickness, it
enters the gluteal region below
the level of the pyriformis muscle
as the great sciatic nerve. This
nerve indeed may be regarded
as the direct continuation of the
sciatic band of the plexus into
the thigh. The
pudendal band is
small, and lies
at a lower level
than the sciatic
band. It takes
origin by roots
which spring
from the second, third,
and fourth sacral nerves,
and unite in a plexiform
>-^ manner to form the band.
It leaves the pelvis through the
lower part of the great sacro-
sciatic foramen, below the pyri-
formis, and is continued directly
into the internal pudic nerve.
The sacral plexus rests upon
the pyriformis muscle ; whilst,
anteriorly, it is clothed by parietal pelvic fascia, which separates
it from the branches- of the internal iliac artery.
The great sciatic nerve divides in the back of the thigh into its internal
and external popliteal branches, and it is not uncommon for these branches
to arise separately from the sacral plexus. Further, even in those cases
where the division does not take place until the nerve has reached the thigh,
it is possible by removal of its sheath to resolve it into its two component
parts and trace these up to their origin from the various nerves which enter
the sciatic band. All the nerves which enter the sciatic band, with the
z >
Fig. 219. — The Sacral and Sacro
coccygeal Plexuses,
from behind.
as seen
PELVIS 559
exception of the upper part of the third sacral nerve, are composed of
anterior and posterior trunks. The posterior trunks of the two nerves which
enter the lumbo-sacral cord, of the first and of the second sacral nerves,
unite to form the external popliteal or peroneal nerfe ; whilst the anterior
trunks of the same nerves, with the upper part of the third sacral nerve,
form by their union the internal popliteal or tibial nerve. Of the subsidiary
branches which spring from the sciatic band within the pelvis, some proceed
from the anterior trunks and others from the posterior trunks (see diagram).
In addition to the two terminal branches of the sacra)
plexus (great sciatic and internal pudic) which have been
seen to be continuations of the two bands into which the
plexus resolves itself, there are various other twigs given off
from it — viz. : —
1. Superior gluteal.
2. Inferior gluteal.
3. Small sciatic.
4. Nerve to the obturator internus and superior gemellus.
5. Nerve to the quadratus femoris and inferior gemellus.
6. Perforating cutaneous nerve.
7. Branches to the pyriformis muscle.
8. Branches to the pelvic viscera.
The superior gluteal nerve (nervus glutaeus superior) arises
on the posterior aspect of the plexus by three roots from
the posterior trunks of the lumbo-sacral cord and of the first
sacral nerve. It leaves the pelvis with the gluteal vessels
through the upper part of the great sacro-sciatic foramen,
and in the gluteal region is distributed to the gluteus
medius, gluteus minimus, and tensor fasciae femoris muscles.
The i?iferior gluteal nerve (nervus glutaeus inferior) is the
special branch of supply to the gluteus maximus. It arises
upon the posterior aspect of the plexus, from the lumbo-
sacral cord and from the first and second sacral nerves, and
gains the gluteal region through the lower part of the great
sciatic foramen below the level of the. pyriformis muscle.
The small sciatic nerve (nervus cutaneus femoris posterior)
is often closely associated at its origin with the preceding
branch. It arises on the posterior aspect of the plexus by
two or more roots from the first, second, and third sacral
nerves, and leaves the pelvis through the lower part of the
great sacro-sciatic foramen.
The nerve to the obturator internus springs from the anterior
aspect of the sacral plexus. It accompanies the pudic nerve
through the great sacro-sciatic foramen into the gluteal region,
where it gives a twig to the superior gemellus. It reaches
the obturator internus by passing through the small sacro-
560 ABDOMEN
sciatic foramen, and ends by sinking into the inner aspect of
this muscle.
The nerve to the quadrates femoris arises from the upper
part of the anterior aspect of the plexus, and enters the gluteal
region by passing through the lower part of the great sacro-
sciatic foramen. It also supplies the gemellus inferior and a
branch to the hip-joint.
The perforating cutaneous fierve arises from the posterior
aspect of the second and third sacral nerves. It pierces the
great sacro-sciatic ligament, and then winds round the lower
border of the gluteus maximus to gain the skin over the
lower and inner part of that muscle.
The twigs to the pyriformis usually spring from the second
and third sacral nerves.
The visceral branches (white rami communicantes) come
from the third and fourth sacral nerves.
Sacro-Coccygeal Plexus. — The fourth sacral ?ierve, as we
have seen, sends upwards a branch to join the sacral plexus ;
it also sends a twig downwards to unite with the fifth sacral
nerve. But in addition to these connecting branches, it gives
off ?nuscular and visceral branches.
The muscular branches are distributed to three muscles —
viz., the levator ani, the coccygeus, and the sphincter ani
externus. The last of these has already been dissected in
the perineum, under the name of the " perineal branch of
the fourth sacral nerve.''
The visceral branches (white rami communicantes) are
numerous, and are directed inwards towards the viscera.
Here they join with the pelvic plexus of nerves. Some,
however, may be found entering the viscera directly. The
third sacral nerve also gives off visceral branches.
The fifth sacral nerve pierces the coccygeus. After being
joined by the branch from the fourth sacral nerve, it turns
downwards and unites with the coccygeal nerve. It supplies
one or two minute filaments to the coccvsreus muscle.
The coccygeal ?ierve is a very delicate filament. It emerges
from the lower end'of the sacral canal, and makes its appear-
ance by piercing the sacro-sciatic ligaments and the coccygeus
muscle. It is now joined by the fifth sacral nerve and runs
downwards. Near the tip of the coccyx it is directed back-
wards through the coccygeus muscle, and ends in the skin
in this neighbourhood.
PELVIS 561
Dissection. — The dissector should, in the next place, make out the
distribution of the sympathetic nerves within the pelvis. These have, no
doubt, been considerably injured in previous dissections, but those which
remain must be carefully traced.
Pelvic Plexuses of the Sympathetic. — The hypogastric
plexus has been observed to end inferiorly by dividing into
two lateral portions, which are prolonged downwards, one
upon each side of the rectum. These are termed the pelvic
plexuses, and each consists of a dense meshwork of sym-
pathetic nerves. In addition to the branches from the
hypogastric plexus, they receive numerous twigs from the
third and fourth sacral spinal nerves, and the points at which
these unite with the sympathetic filaments are marked by
minute ganglia. The pelvic plexuses also acquire branches
from the sacral portion of the sympathetic cord.
Prolongations from the pelvic plexus upon each side are
sent along the various branches of the internal iliac artery.
There are thus formed various secondary plexuses — viz., the
vesical plexus, to the coats of the bladder, to the seminal
vesicle and the vas deferens ; the hcemorrhoidal plexus, to the
rectum ; and the prostatic plexus, to the prostate.
The prostatic plexus proceeds forwards between the prostate
and the levator ani, and sends twigs to the erectile tissue of the
penis. These latter are termed the cavernous ?ierves.
Gangliated Cord of Sympathetic. — The sympathetic cord
as it enters the pelvis is considerably reduced in size. It
proceeds downwards in front of the sacrum, along the inner
side of the anterior sacral foramina. Above, it is continuous
with the lumbar portion of the sympathetic cord, whilst
below, it ends in the mesial plane in front of the coccyx
in a minute ganglion, termed the ganglion i?npar, which acts
as a bond of union between the cords of the two sides.
The ganglia are very variable in number, but as a general
rule there are four. Each of these is brought into connection
with the spinal nerves by short grey rami communicantes.
The branches of these ganglia are chiefly distributed upon
the anterior surface of the sacrum and around the middle
sacral artery. A few filaments from the upper part of the
gangliated cord are given to the pelvic plexuses, and some
minute twigs proceed from the ganglion impar to the parts
about the coccyx and to the coccygeal body.
Coccygeal Body. — This is a minute lobulated body about
vol. 1 — 36
562 ABDOMEN
the size of a small pea, and situated in front of the tip of
the coccyx. It is composed of masses of polyhedral cells,
separated from each other by strands of connective tissue.
Numerous sympathetic twigs, and also minute branches of
the middle sacral artery, enter it.
Removal of the Viscera. — The viscera must now be removed from the
pelvic cavity. Begin by dividing the vessels and nerves which enter
them, the levator ani, and the pubo-prostatic ligaments. Then sever
the parts which hold the membranous portion of the urethra and the
bulb of the penis to the pubic arch. Great care must be taken at this stage
not to injure the delicate walls of the urethra, or to lose sight of Cowper's
glands. Lastly, separate the rectum from its connections with the coccyx.
Laying aside the viscera for a little, the dissector should study the muscles
in relation to the pelvic wall — viz., the obturator interims and the
pyriformis.
Obturator Internus. — This muscle clothes the lateral wall
of the pelvis upon its inner aspect. Remove the parietal
layer of the pelvic fascia, and it will come into view. It is
a fan-shaped muscle, and has an extensive origin, viz. — (i)
from the circumference of the thyroid foramen, except above,
where the obturator vessels and nerve quit the pelvis ; (2)
from the deep surface of the membrane which extends across
the foramen; and (3) from the surface of bone behind the
thyroid foramen as far back as the great sciatic notch. A
few fibres are also derived from the parietal pelvic fascia
which covers it. From this origin the fibres converge towards
the small sciatic notch, and end in a tendon which issues
from the pelvis through the lesser sacro-sciatic foramen.
Entering the gluteal region, it is inserted in conjunction with
the gemelli muscles into the upper part of the great trochanter
of the femur. The small sciatic notch, over which the
tendon glides, is coated with smooth cartilage, and this
is raised into three or four parallel ridges, which fit into
fissures upon the deep surface of the tendon. A synovial
bursa intervenes between them.
The obturator internus is supplied by a special branch
from the upper part of the sacral plexus.
Pyriformis. — The pyriformis is placed against the anterior
aspect of the posterior wall of the pelvis. It arises by three
processes, from the anterior surface of the second, third, and
fourth sacral vertebrae between the sacral foramina ; it also
takes origin from the innominate bone, where it forms the
upper part of the great sciatic notch, and from the great
PELVIS 563
sacro-sciatic ligament. The muscle leaves the pelvis through
the great sacro-sciatic foramen, and is inserted by a rounded
tendon into the top of the great trochanter of the femur. It
is supplied by branches from the sacral plexus.
Structure of the Wall of the Rectum. — Turning now to
the pelvic viscera, separate the rectum and anal canal from
the bladder and prostate, and, having stuffed the rectum
moderately with tow, proceed to dissect its walls. The
rectum presents several coats, viz. : —
1. Serous.
2. Aponeurotic.
5. Mucous.
3. Muscular.
4. Submucous.
The serous and aponeurotic coats have already been
examined. The serous coat is altogether absent from the
lower third of the rectum, whilst it only gives a partial
covering to its upper two-thirds. It clothes its upper portion
anteriorly and laterally, whilst lower down, before it leaves
the gut, it is only found on its anterior aspect. The
aponeurotic sheath is only present in the lower part of the
rectum. It is derived from the visceral pelvic fascia in
the manner already described.
The muscular coat is thick and strong, and is composed
of two layers of involuntary non-striated muscle-fibres — viz.,
an external longitudinal and an internal circular layer. The
longitudinal fibres are continuous above with the three
longitudinal bands of the colon. As these bands approach
the rectum, the fibres which compose them spread out, so as
to form a continuous layer round the rectum. This layer,
however, is not uniformly thick on all aspects of the gut.
On the front and on the back the fibres are massed together
into broad anterior and posterior bands, which are so disposed
that they maintain the flexures of the rectum, and prevent it
from elongating as it becomes loaded with contents. The
circular muscular fibres extend transversely around the gut, and
form a continuous and more or less uniform layer, subjacent
to the longitudinal fibres.
The submucous coat is composed of lax areolar tissue, which
allows the mucous membrane to move freely upon the muscular
coat.
Interior of the Rectum. — The rectum and the anal canal
may now be opened by dividing the anterior wall in the
mesial plane with the scissors. The mucous membrane of
5 64 ABDOMEN
the rectum is thicker than that of the colon, and is more
freely movable upon the muscular tunic. In consequence of
this mobility, it is thrown into irregular folds or rugae when
the gut is empty. It presents a punctated appearance, from
the presence of numerous minute tubular pits, around the
bottom of which lymphoid tissue is accumulated (Birmingham).
The rectal valves or valves of Houston should now be
visible, although they show best when the rectum is distended.
They are three horizontally disposed crescentic infoldings
of the wall of the rectum, which help to support the contents
of this portion of the gut when it is loaded. They corre-
spond to the inflections of the wall of the gut which are
produced by its lateral flexures. Consequently they are
usually three in number — two on the left side and one on
the right side, — and each is formed by an infolding of the
mucous, submucous coats, and to some extent also of the
muscular coat. The position of these valves is variable ; but,
speaking generally, the right valve is placed at the level of
the bottom of the recto-vesical pouch, whilst the two left
valves are respectively situated about an inch and a half
above and about the same distance below the intermediate
right valve (Birmingham).
Anal Canal. — The anal canal has a very thick and
powerful muscular wall. The internal circular layer of
muscular fibres is prolonged downwards from the rectum,
and becomes greatly thickened in the wall of the anal canal.
The muscular cylinder thus formed constitutes the internal
sphi?icter, which embraces the whole length of the canal, with
the exception of its lower half -inch. The longitudinal
muscular fibres of the rectal wall are also prolonged downwards
in association with the fibres of the levator ani on the outer
aspect of the internal sphincter. The external sphincter
surrounds the lower part of the canal on the outside of the
levator ani.
It is sometimes stated that the thick anterior portions of the levator ani
clasp between them the upper part of the anal canal by passing back on
either side of it. It is a difficult matter to state definitely the precise
relations of the levator ani to the anal canal and rectum. Unquestionably
there is a thick collar of muscular fibres surrounding the gut in this situation,
but it is more than doubtful if it is formed by the anterior fibres of the
muscle alone.
The mucous lining of the anal canal presents certain
characteristic features. In the upper part of the canal it is
PELVIS
565
thrown into a series of longitudinal folds termed the columnar
rectce or the columns of Morgagni. A short distance above the
orifice of the anus the lower ends of these are connected with
each other by a number of faintly marked, irregularly dis-
posed, semilunar folds which are arranged circularly around
the gut. These are the anal valves, and when strongly
developed they form a number of little pocket-like recesses
between the vertical columns (sinus Morgagni). It is here
that the scaly epithelium of the integument merges into the
columnar epithelium of the gut. These semilunar folds are
of importance in connection with the condition known as
" fissured anus " (Ball).
Anal canal
Region of
the columns
of Morgagni
and anal
valves
Sphincter ani
externus
Fig. 220. — The lower part of the Rectum and the Anal Canal opened up.
(Charles B. Ball. )
Dissection. — The bladder must be fully distended with air before the
dissection of its walls is commenced.
Coats of the Bladder. — The bladder presents the follow
ing coats : —
1. Serous.
2. Subserous.
Mucous.
3. Muscular.
4. Submucous.
The serous covering is partial and confined to its superior
part. The subserous coat consists of a thin stratum of
areolar tissue which binds the peritoneum to the muscular
coat. The vesical layer of pelvic fascia may be considered to
thin away into this coat.
566
ABDOMEN
The muscular tunic presents three layers of non-striated
muscular fibres, viz. : —
1. External longitudinal fibres.
2. Circular fibres.
3. Internal longitudinal fibres.
The external longitudinal fibres, frequently termed the
detrusor urince, are most apparent upon its inferior and superior
surfaces. They may be considered to spring from the back
of the pubic bones, the pubo- prostatic ligaments, and the
base of the prostate. From these attachments they mount
upwards and spread out upon the inferior surface of the
Folds in mucous
membrane
Urethral orifice
Trigone
Ridge connecting orifices of ureters
Fig. 221. — Interior of Bladder in region of Urethral Orifice.
(A. F. Dixon.)
bladder. At the apex, a few pass on to the urachus, but
the majority are carried backwards over the superior aspect
and base of the bladder to the prostate, to which they are
attached. On the sides of the bladder this layer is not so
complete and the fibres take a more oblique direction.
The circular fibres are arranged in coarse bundles, many of
which run obliquely as well as circularly around the organ
and constitute the chief bulk of the muscular coat. At the
urethral orifice the bundles become much finer and are massed
together to form a sphincter — the fibres of which are more
or less continuous with those of the prostate.
The i?iternal longitudinal fibres constitute an incomplete
layer which only exists on the inferior wall, and to some
PELVIS 567
extent on the superior wall of the bladder. It is not present
in the basal part of the bladder.
The submucous coat is the loose areolar bed in which the
blood-vessels and nerves ramify before they enter the mucous
membrane. It connects the mucous and muscular coats, and
has a considerable amount of elastic tissue entering into its
composition.
Dissection. — The mucous membrane which lines the bladder should now
be examined, and, for this purpose, it is necessary to open up the viscus by
an incision along its inferior aspect from the apex to the neck. It is better
to lay open the first portion of the urethra at the same time by carrying the
incision along the mesial plane through the anterior part of the prostate.
Mucous Membrane of the Bladder. — When the mucous
membrane is washed, it will be observed to be highly rugose,
except over a triangular area immediately above and behind
the urethral orifice. This rugosity is due to the loose manner
in which the membrane is bound by the submucous layer to
the muscular coat. When the bladder is distended, the folds
are effaced, and the mucous lining becomes smooth.
Orifices of the Bladder. — The orifice of the urethra
(orificium urethras internum), or the canal which conducts the
urine to the surface, is situated on the back portion of the
inferior wall of the bladder. Immediately behind this, the
mucous membrane is frequently observed, especially in aged
people, to be elevated so as to form a slight prominence,
which bulges forwards over the aperture. This elevation is
termed the uvula vesica, and it results from an enlargement
of the so-called middle lobe of the prostate, which lies
behind it.
When the bladder is hardened in situ and the interior examined by the
removal of the superior wall of the viscus, the urethral orifice is seen to be
tightly closed and the mucous membrane arranged in minute radial folds
around it. The outline of the base of the prostate is also, as a rule, visible
in the form of a faint circular elevation with the urethral orifice in the
centre (Fig. 222).
Probes should now be passed along the ureters into
the interior of the bladder. By this means the dissector
will be able to see how very obliquely these ducts pierce
the walls of the bladder. Indeed, they traverse the wall
for more than three-quarters of an inch before they reach
the internal orifices. This arrangement, whilst it permits the
passage of urine from the ureter into the bladder, exercises
a valvular action in distension of the viscus, and prevents
1—36"
568
ABDOMEN
any backward flow of the urine into the ureters. The open-
ings of the ureters (orificia ureterium) are two slit-like apertures,
which are placed, in the full bladder, about an inch and a
half apart from each other, and about the same distance from
the urethral orifice. When the viscus is empty and con-
Symphysis pubis
Position of prostate
Urethral opening
Opening
Ureter pierci
vail of bladder
Seminal
vesicle
V
defere
urator foramen
Obturator vessels
and nerve
Ureter
Inferior vesica
middle hsemor
rhoidal arterie
Pelvic pi
•bturator
internus \^
Parietal ,
pelvic fascia
Pyriformis'
iciatic and inter
al pudic arterie:
Pelvic plex
Sacral pi
Sacro
wast*/
/ Parietal pe!\
fascia
( iluteal artery
piercing parieta
pelvic fascia
ciatic and intern
pudic arteries
mbo-sacral cord z
acral nerve
Pranches of superior
haemorrhoidal artery
Terminal portion
of pelvic colon
Fig. 222. — Oblique section from above downwards and forwards through
the Pelvis. The peritoneum has been removed so as to expose the
viscera and the parietal pelvic fascia clothing the pelvic wall.
tracted, however, the three orifices are brought closer to each
other and the intervals between them are reduced to about
one inch in each case.
Trigone of the Bladder. — The three orifices of the bladder
constitute the angles of an equilateral triangle, which is
termed the trigone, the boundaries of which are formed by
lines drawn between the openings of the ureters and from
PELVIS 569
each of these forwards to the urethral orifice. As a rule,
the base of the trigone is distinctly indicated by a smooth
curved ridge which extends between the apertures of the
ureters with its convexity directed downwards towards the
urethral orifice or apex of the triangle. This ridge is called
the torus itretericus, and it is produced by a transverse bundle
of muscle-fibres under the mucous membrane.
The mucous membrane over the trigone of the bladder
presents a marked contrast to the same membrane in other
parts of the bladder. Here it is always smooth, in whatever
condition the viscus may be, and this is due to its being
tightly bound down to the subjacent muscular coat. It is
also said to be more sensitive than in other parts of the
bladder.
Dissection. — The bladder should now be pinned out on the bottom of a
cork-lined tray filled with water. When this is done the mucous membrane
over the trigone may be carefully raised. The band of muscular fibres
which produces the torus uretericus at the base of the trigone will be
observed running between the two ureters. In certain cases another band
may be traced from the ureter along each side of the trigone towards the
urethral orifice.
Urethra (urethra virilis). — The urethra is the canal through
which the urine, the semen, and the secretions of the
vesiculae seminales, the prostate, and Cowper's glands are
emitted from the body. It commences at the neck of the
bladder and ends on the glans penis, and its average length
is somewhere about eight or nine inches. It is customary
to divide the urethra into three parts, from the different
character of the structures which it traverses. The first
or prostatic portion (pars prostatica) is contained within the
substance of the prostatic gland ; the second or membranous
portion (pars membranacea) extends from the prostate to the
bulb of the corpus spongiosum penis, and is surrounded by
the fibres of the compressor urethra? muscle ; whilst the third
or spongy part (pars cavernosa) traverses the entire length of
the corpus spongiosum.
Dissection. -The urethral canal must now be laid open throughout its
whole length, in order that its various parts may be studied. Lay the
bladder and penis upon a block, and extend the incision which has already
been made through the prostate, along the upper wall of the membranous
portion of the urethra, and along the dorsum of the penis between the tv><'
corpora cavernosa and through the glans. This cut must be made as far
as possible in the mesial plane.
57o
ABDOMEN
Prostatic Portion of the Urethra. — This part of the
urethra is about one inch and a quarter in length. It traverses
the prostate in front of its so-called middle lobe, and takes
a very nearly vertical course through its substance. It is the
widest and at the same time the most dilatable part of the
canal; and further, it is fusiform, being wider in the middle
than at either its commencement or termination.
Ureter
Vas deferens --
Vesicula
seminalis
Middle lobe
of prostate
Sinus pocu-
laris and
ejaculatory
duct
Cowper's
gland
Bull
Urachus
Bladder
Glans penis
Fig. 223. — Diagram of the Bladder, Urethra, and Penis. (Del^pine. )
In connection with the posterior wall or floor of the
prostatic portion of the urethra, there are certain important
features to be noted. The mucous membrane along the
mesial plane is raised into a prominent ridge called the
verumontanum.1 This commences a short distance below the
orifice of the urethra in the bladder, and extends downwards
for about three-quarters of an inch. Above, it rises to a
considerable height, but below, it gradually fades away. On
1 Other terms are applied to this mesial ridge on the floor of the
urethra — viz., crest of the urethra, colliculus seminalis, and caput
eallinasinis
PELVIS 571
each side of the verumontanum, the floor of the urethra is
hollowed out into a longitudinal depression, termed the
prostatic sinus, into which numerous prostatic ducts open. This
may be rendered evident by squeezing the prostate, when
fluid will be observed to exude into the two sinuses. These
ducts proceed from the glandular substance of the prostate.
A close inspection of the floor of the urethra above the veru-
montanum will reveal the apertures of the ducts of the so-
called middle lobe of the prostate.
Immediately below the highest part of the verumontanum,
the mucous membrane dips backwards and upwards behind
the middle lobe of the prostate, so as to form a small recess
or cul-de-sac. This is the sinus pocularis or the utriculus.
Gauge its extent by means of a probe. It will be observed
to be from a quarter to half an inch long, and to be narrow
at its orifice, but to widen out considerably towards its
blind extremity. It is of interest, both from a develop-
mental and a surgical point of view. It is the representa-
tive, in the male, of the uterus and vagina in the female.
Practically, it is important, because in some cases it is
large enough to entangle the point of a small catheter or
bougie.
The dissector should now pass bristles along the common
ejaculatory ducts. They run downwards between the so-called
middle and lateral lobes of the prostate. Finally, entering
the wall of the sinus pocularis, they open by slit-like apertures,
just within the margin of its orifice.
Owing to the presence of the verumontanum on the floor
of the canal, and the prostatic sinus upon each side of it, a
transverse section of the prostatic portion of the urethra
presents a crescentic figure — the convexity of the crescent
being directed forwards and the concavity backwards.
As old age approaches, the prostate is very liable to become enlarged,
and the most important result of this is the effect which it exerts upon the
urethra. When the enlargement is uniform, the prostatic portion of the
canal is simply elongated ; when, however, the enlargement is confined to
one part of the gland, it impinges upon the urethra, and produces an
alteration in its direction, and a consequent difficulty in micturition.
When the middle lobe alone is increased in size, it may project forwards into
the bladder so as to close the commencement of the canal. It is only in
pathological conditions of the prostate that the so-called middle lobe
becomes a distinct and more or less independent part of the organ. In
health it is merely marked off from the rest of the prostate by the presence
of the ejaculatory ducts and the sinus pocularis in the substance of the
organ.
572 ABDOMEN
Membranous Portion of the Urethra. — This is the narrowest
and the shortest division of the urethra. It extends from the
prostate to the bulb of the penis, and describes a gentle
curve from above, downwards and forwards, behind the lower
border of the symphysis pubis, from which it is distant about
one inch. Its length is barely three-quarters of an inch, and
its concavity is directed forwards and upwards, and its
convexity backwards and downwards. Throughout its entire
extent it is enveloped by the fibres of the compressor urethra?
muscle, whilst towards its termination Cowper's glands are
placed behind it — one on each side.
The relation of the membranous part of the urethra to
the triangular ligament and the parietal pelvic fascia is
important. As it emerges from the prostate, it pierces the
parietal pelvic fascia {i.e., the deep layer of the triangular
ligament), and the margins of the aperture through which it
passes are carried backwards to become continuous with the
sheath of the prostate. At its termination it pierces the
triangular ligament proper about an inch below the symphysis
pubis. It may therefore be looked upon as lying in the
interval between these membranes.
Immediately subjacent to the mucous membrane the membranous part
of the urethra is surrounded by a thin coating of erectile tissue, outside
which there is a muscular tunic composed of involuntary fibres arranged
circularly.
Spongy Portion of the Urethra. — This is the longest division
of the urethra. It is embedded throughout in the substance
of the corpus spongiosum penis, and shows considerable
differences in its calibre as it is followed forwards to the glans.
At each expansion of the corpus spongiosum there is a
corresponding dilatation of the urethra. Thus the canal
presents two dilatations — (i) in the bulb, and (2) in the
glans ; between these it is of uniform diameter, and slightly
wider than the membranous part. The dilatation of the
urethra in the glans is termed' the fossa naviadaris. At its
orifice, which is termed the meatus urinarius, the canal is
much contracted, and is even narrower than any part of the
membranous portion. This aperture is a vertical slit, the
lower end of which is connected with the prepuce by a
fold of mucous membrane, termed the frenum preputii.
In the bulb and in the glans penis the erectile tissue of
the corpus spongiosum is disposed very unequally around the
PELVIS
urethra. In the former it is chiefly massed below or behind
the tube, whilst in the glans it is chiefly placed in front and
upon each side, a very thin layer covering it posteriorly.
The ducts of Cowper's glands open into the spongy portion
of the urethra by piercing its floor about an inch in front
of the triangular ligament. These orifices are extremely
minute, and difficult to find.
By making a small hole in the wall of the duct as it emerges from the
gland, and passing a fine bristle along it, the dissector may be able to
detect the opening in the urethral floor. The ducts proceed in the first
place through the erectile tissue of the bulb, but towards their termination
they lie immediately subjacent to the mucous membrane.
Fibrous capsule of the Prepuce
corpus cavernosuni
Glans penis
navicularis
penis
acuna magna
Corpus spongiosum
Fig. 224. — Mesial section through terminal part of the Peni; :
Prepuce extremely short.
The walls of the urethra are always in apposition except
when urine is flowing through it. A transverse section
through the spongy portion, except at its anterior part, would
give the appearance of a transverse slit. In the fossa
navicularis, however, the slit becomes vertical, showing that
here the side walls are in contact.
Mucous Membrane of the Urethra. — The mucous lining of
the urethra is continuous posteriorly with that of the bladder,
and anteriorly with the integument covering the glans penis.
It is likewise continuous with the mucous membrane which
lines the various ducts which open into the urethra. It is
everywhere studded with the mouths of minute recesses, called
lacuna uretkrales. These are particularly plentiful on the floor
574 ABDOMEN
of the spongy part, and, as a general rule, they are directed
forwards towards the meatus urinarius.
Direction of the Urethral Canal. — The prostatic portion
is directed downwards and very slightly forwards ; the
membranous part describes a slight curve behind the sym-
physis, the concavity of which looks forwards ; whilst the
spongy part at first ascends, and then curves downwards.
The urethra, therefore, in the flaccid condition of the
penis, takes a course in which there are two curves, like
the letter co reversed. When the penis is raised towards the
front of the abdomen the curve in the spongy part of the canal
is obliterated, and there is now only one curve, the concavity
of which is directed upwards.
Structure of the Prostate. — In the course of an ordinary
dissection it is not to be expected that the dissector
will be able to make out the structure of the prostate in
all its details. It is mainly composed of involuntary
muscular tissue. This tissue forms a layer on the outside
of the organ, and also gives a coating to the urethra
as it traverses the prostate. The outside and inside fibres
are continuous in front — indeed, the greater part of the
anterior portion of the prostate is muscular. The fibres sur-
rounding the urethra are also to some extent continuous above
with the circular fibres of the bladder, and below with the
circular fibres of the membranous part of the urethra ; further
they radiate out into the substance of each lateral part of the
gland. The glandular tissue is interspersed amidst the muscular
bundles, but, as a rule, none is to be seen in front of the
urethra.
Structure of the Penis. — In the dissection of the urethra
the corpora cavernosa penis have been separated from each
other. Each will be seen to be enveloped in an exceedingly
strong fibro-elastic sheath. In the mesial plane the sheaths
become continuous with a strong septum, which intervenes
between the two cylindrical masses. This septum receives
the name of septum pectiniforme, because in front it is very
imperfect, being broken up by vertical slits into a series of
processes like the teeth of a comb. The two fibrous cases
thus constructed are filled with erectile tissue. Fibrous
lamellae and bands proceed from the deep surface of each
sheath and join with each other to form a spongy framework.
The interstices of this framework freely communicate with
PELVIS
575
each other, and are filled with venous blood. By squeezing
the corpora cavernosa under the tap and washing out the
blood some idea of the trabecular may be obtained.
The corpus spongiosum has a similar structure. The
enclosing sheath, however, is very delicate, and the trabecular
are much finer.
Vesiculse Seminales. — If the dissector has not already
unravelled the vesicular seminales, he should now do so,
and, at the same time, endeavour to make out the composition
of their walls. This can best be done under water. In
addition to the sheath derived from the recto-vesical fascia,
Dorsal vein of penis Dorsal artery
Fibrous capsule of
corpus cavernosum
Corpus cavernosum <£_
Artery to corpus /
cavernosum 1 ~|p
*^v Dorsal nerve
<3 e^\ Fibrous capsule of
_ corpus cavernosum
„ v
-r^fPl '-^F^j^^l. \ \ Septum
~~~. pectiniforme
Erectile tissue
of corpus
cavernosum
Corpus spongiosum
FlG. 225. — Transverse section through the anterior part of the body
of the Penis.
each vesicle has a strong dense fibrous tunic and a certain
proportion of transverse and longitudinal non-striated muscular
fibres entering into the formation of its wall. Open them
up and expose the ?nucous lining. This is remarkable for its
honeycomb or reticular appearance. In this respect, therefore,
it is not unlike the mucous membrane of the gall-bladder,
only the meshes are finer and the pits smaller.
Pelvic Articulations.
The pelvis is attached to the last lumbar vertebra, and its
several parts are held together by the following articulations :
— (1) Lumbo-sacral; (2) Sacro -coccygeal ; (3) Coccygeal,
(4) Sacro-iliac ; (5) Pubic.
576 ABDOMEN
Dissection. — The nerves and blood-vessels of the pelvis must now be
removed, and all adhering portions of muscle detached from the left in-
nominate bone and the front and back of the sacrum. When this is done,
the pelvis should be soaked for some time in warm water. By this pro-
ceeding the dissection of the ligaments will be rendered much easier.
Lumbo-sacral Articulations. — The last lumbar vertebra
is joined to the sacrum by one amphiarthrodial joint, which
connects the body of the vertebra to the base of the sacrum,
and by two diarthrodial joi?its, between the twTo pairs of
articular processes.
Capsular ligaments (capsular articulares) surround the
articulations formed by the apposition of the articular pro-
cesses, and each is lined by a synovial membrane.
The anterior' co??imo?i liga?nent (ligamentum longitudinale
anterius) of the vertebral column is continued downwards
over the anterior aspect of the body of the last lumbar
vertebra to the anterior aspect of the first segment of the
sacrum. In a similar manner the posterior comnion ligament
(ligamentum longitudinale posterius) is prolonged downwards
within the spinal canal, over the posterior aspect of the body
of the last lumbar vertebra, to the upper part of that portion
of the sacrum which forms the anterior wall of the sacral
canal.
Liga?nenta subflava (ligamenta flava) are also present.
These are twro short bands of yellow elastic tissue placed one
on each side of the mesial plane. Superiorly they are attached
to the anterior aspect of the lower borders of the laminae of
the last lumbar vertebra ; whilst inferiorly they are fixed to
the posterior aspect of the upper margins of the laminae of
the first sacral segment.
An interspinoas ligament (ligamentum interspinal) connects
the lower border of the spinous process of the last lumbar
vertebra writh the upper border of the spinous process of
the first sacral vertebra. A supraspinous ligament (ligamentum
supraspinal) bridges across between the extremities of the
same spinous processes.
So far, then, the ligaments of the lumbo-sacral articulations
are identical with those which, above the level of the sacrum,
bind the several segments of the spinal column together. Two
additional ligaments — viz., the lumbo-sacral and the ilio-lumbar,
must now be examined.
The lumbosacral ligament is the representative of the superior
costo-transverse ligaments. It is a strong triangular fibrous
PELVIS
577
band attached by its apex to the tip and lower border of the
transverse process of the last lumbar vertebra. Expanding
as it proceeds downwards, it is fixed below to the posterior
part of the base of the sacrum, where some of its fibres
intermingle with those of the sacro-iliac ligaments.
The Mo-lumbar ligament (ligamentum iliolumbale) may be
Reflected
head of
Iliolumbar
ligament
Posterior
sacro-iliac
ligament
Long or
oblique
posterior
sacro-iliac
ligament
Great
sacro-sciatic
foramen
Small
sacro-sciatic
ligament
Small
sacro-sciatic
foramen
Great
sacro-sciatic
ligament
Obturator
membrane
Fig. 226. — Posterior View of the Pelvic Ligaments and of the Hip-joint.
considered to be a thickened and specially developed part
of the anterior lamella of the lumbar fascia. It lies in the
same plane and is directly continuous with it. It is triangular
in shape, and is fixed by its apex to the tip of the transverse
process of the last lumbar vertebra. Proceeding horizontally
outwards, it is inserted into the inner lip of the iliac crest at
the posterior part of the iliac fossa.
The amphiarthrodial joint, between the body of the last
vol. 1 — 37
578 ABDOMEN
lumbar vertebra and the base of the sacrum, corresponds in
every respect with the similar articulations above, between the
bodies of the vertebrae. The opposed bony surfaces are each
coated by a thin layer of hyaline cartilage, and are firmly
united by an intervening disc of fibro-cartilage, which is dense
and laminated externally, soft and pulpy towards the centre.
The dissector should observe that this disc is the thickest of
the series, and further, that it is wedge-shaped, being thicker
in front than behind.
Sacro-coccygeal Articulation. — This is an amphiarthrodial
joint. The articulating surfaces are each covered by a thin
cartilaginous plate, and these are united by a disc of fibro-
cartilage. The joint is strengthened in front by an anterior
ligament, which extends downwards from the front of the
sacrum to the anterior aspect of the coccyx, and by a posterior
ligament which, attached above to the posterior border of the
lower aperture of the sacral canal, proceeds downwards upon
the posterior aspect of the coccyx. The latter ligament is
much the stronger of the two. In addition, fibrous bands
will also be found passing between the cornua of the sacrum
and the coccyx, and also between the lateral angles of the
sacrum and the transverse processes of the first piece of the
coccyx.
As regards the coccygeal joints (when such exist), the union
of the different segments of the bone is brought about by
intervening cartilaginous discs and anterior and posterior
ligaments.
Dissection. — The student should now saw through the sacrum and coccyx
in the mesial plane. By this proceeding he will obtain a view of the
structure of the intervertebral discs, and at the same time be enabled to
make out to better advantage the attachments of the posterior common
vertebral ligament and of the ligamenta subflava.
Sacro-iliac Articulation. — The sacrum is wedged in between
the two innominate bones, and is held fast in this position by
the sinuous form of the opposed articular surfaces and the
strong ligaments which pass between the bones. These
ligaments are —
i. The anterior sacro-iliac.
2. The posterior sacro-iliac.
3. The oblique sacro-iliac.
4. Great sacro-sciatic.
5. Small sacro-sciatic.
PELVIS
579
The anterior sacro-iliac ligament (ligamentum sacroiliacum
anterius) is by no means strong. It is composed of a series of
short fibres stretching across in front of the joint, and con-
necting the bones anteriorly.
The posterior sacro-iliac ligament (ligamentum sacroiliacum
interrosseum) is exceedingly strong. It consists of fibrous
bands, which connect the rough surface on the posterior part
of the lateral aspect of the sacrum with a corresponding rough
surface on the ilium, behind the auricular surface. Upon
the posterior sacro-iliac ligaments the strength of the articu-
Posterior sacro-iliac
-iliac joint
( irtr-ut sacro
sciatic foramen
*£ \ L>reat sacro
>m;
ciatic ligament
Small sacro-
sciatic ligament
sacro-sciatic
foramen
Acetabulum
Great sacro-sciatic
ligament
ic fibre-cartilage
Fig. 227. — Coronal section through the Pelvis.
lation chiefly depends. As the sacrum narrows towards its
dorsal surface it cannot be regarded in any sense as forming
the keystone of an arch. It may be regarded as being in a great
measure suspended from the iliac bones by these ligaments.
The oblique liga?netit is simply a specially thickened part of
the posterior sacro-iliac ligament. Above, it is fixed to the
posterior superior spine of the ilium ; whilst, inferiorly, it is
inserted into the lateral tubercle of the third piece of the
sacrum.
The great sacro-sciatic ligament (ligamentum sacrotuberosum)
has a wide attachment to the posterior inferior iliac spine and
to the side of the sacrum and coccyx. Narrowing consider-
58o ABDOMEN
ably as it proceeds downwards and forwards, it again expands,
and is inserted into the inner border of the tuberosity of the
ischium. From this it sends upwards a sharp falciform edge,
which extends forwards for. a short distance upon the ascend-
ing ramus of the ischium, and gives attachment to the parietal
pelvic fascia. It should be noticed that at its ischial attach-
ment, some of its fibres pass continuously into the tendon of
the biceps muscle.
The small sacro-sciatic ligament (ligamentum sacrospinosum)
is triangular in form. By its base it is fixed to the side of
the sacrum and coccyx in front of the great sacro-sciatic
ligament, the fibres of both mingling together ; by its apex
it is attached to the spine of the ischium. The pelvic surface
of this ligament presents an extremely intimate connection
with the coccygeus muscle ; indeed, it is generally believed
that the ligament is derived from the superficial part of the
muscle by the fibrous degeneration of its fasciculi.
The two sacro-sciatic ligaments convert the sciatic notches
of the innominate bone into foramina. Through the great
sacro-sciatic foramen pass the gluteal vessels and superior
gluteal nerve, the pyriformis muscle, the sciatic vessels and
nerves, the inferior gluteal nerve, the internal pudic vessels
and nerve, the nerve to the obturator internus, and the nerve
to the quadratus femoris.
The small sacro-sciatic foramen transmits the obturator
internus muscle, the pudic vessels and nerve, and the nerve
to the obturator internus.
A synovial cavity is present in the sacro-iliac joint. The
ligaments of the joint should now be divided, and the two
bones forcibly wrenched asunder. By this proceeding each
articular surface will be seen to be covered with a plate of
cartilage, between which a small synovial space may be
observed, which partially separates them.
The sacro-iliac joint is not immovable, as is sometimes
stated. A slight amount of movement can take place — the
sacrum moving round an imaginary line drawn transversely
through its second piece from one side to the other. In
the erect posture the promontory of the sacrum is withdrawn
to the full extent from the symphysis ; in bending the body
forwards, it approaches, in a small degree, the symphysis, and,
in consequence, the tension of the sacro-sciatic ligaments is
increased.
PELVIS 5S1
Symphysis Pubis. — This is an example of an amphi-
arthrodial joint. In addition to the intervening disc of
fibro-cartilage which connects the cartilage-covered opposing
surfaces of the two pubic bones, four ligaments are present,
viz. : —
1. Anterior pubic.
2. Posterior pubic.
3. Supra-pubic.
4. Infra- or sub-pubic.
The anterior pubic ligament is strongly marked, and consists
of two layers of fibres — a superficial and a deep. The
superficial fibres are oblique, and cross each other like the
limbs of the letter X, mingling with the decussating fibres
of the internal pillars of the external abdominal ring. The
deep fibres are transverse, and extend across from one bone
to the other.
The posterior pubic ligament consists of a very few fibres
on the posterior aspect of the joint.
The supra-pubic ligament, like the preceding, is weak.
It is placed upon the upper aspect of the symphysis, and
stretches between the crests of the two pubic bones.
The infra- or sub-pubic ligament, which is situated on the
lower aspect of the joint, rounds off the apex of the pubic
arch. It is a strong band, somewhat triangular in shape,
which is attached on each side to the descending ramus
of the pubic bone, and above, to the fibro- cartilaginous
disc. Between the crescentic lower margin of this ligament
and the upper border of the transverse perineal band of
the triangular ligament of the urethra, there is an oval
aperture through which the dorsal vein of the penis passes
backwards.
Dissection. — The saw should now be used, and a portion sliced off from
the front of the joint. The intervening plate of fibro-cartilage can in this
way be studied. It will be seen to be thicker and denser in front than
behind. As a general rule, a small synovial cavity will be found towards
its back part, and nearer its upper than its lower end.
Obturator or Thyroid Membrane. — This is the membrane
which stretches across the thyroid foramen. It is attached
to the circumference of the foramen, except at its upper part,
where it bridges across the groove on the under surface of
the horizontal ramus of the pubic bone, and converts it into
a foramen for the escape of the obturator vessels and nerves.
At this point it is continuous over the upper border of the
obturator intern us muscle with the parietal pelvic fascia.
582
ABDOMEN
Female Pelvis.
The contents of the female pelvis are the following
Viscera.
1. The pelvic colon and rectum.
2. The bladder and urethra.
3. The uterus and vagina.
„, . ( Fallopian tubes.
4. The uterine \ r\ • *
^ , -J Ovaries, etc.
' PP I Round ligament.
Utero-sacral fold or torus uterini
I Posterior vaginal fornix
/ / Anterior vaginal fornix
bic
pad of fat
Fig. 228. — Mesial section through Female Pelvis.
Blood-vessels
Nerves.
I
1. Internal iliac vessels and their branches.
2. The superior haemorrhoidal vessels.
3. The middle sacral vessels.
4. The ovarian vessels.
5. Certain venous plexuses in connection with the
viscera.
1. The sacral and sacro-coccygeal plexuses and
their branches.
2. The obturator nerves.
3. The pelvic part of the sympathetic.
The peritoneum is continued into the pelvis, and clothes
some of the viscera completely and others partially.
General Position of the Viscera. — The pelvic colon lies in
the hinder and upper part of the cavity, and its loops tend to
overlap the viscera which lie in front. The rectum, as in th
PELVIS
583
male, occupies the lower and posterior part of the pelvic
cavity, and is adapted to the concavity of the sacrum and
coccyx. The bladder and urethra are situated in front, the
former lying against the posterior aspect of the pubic bones.
The uterus and vagina are intermediate in position ; whilst
the uterine appendages are placed laterally. Three tubes or
canals are thus directed down-
wards to open on the surface
within the limits of the per-
ineum, viz. (a) the urethra ;
(b) the vagina ; (c) the rectum.
(Figs. 228 and 229.)
Peritoneum. — The peri -
toneum, as it proceeds down-
wards from the posterior ab-
dominal wall into the pelvis,
comes into relation with the
pelvic colon, gives it a com-
plete covering, and connects
it to the anterior surface of
the sacrum by a pelvic meso-
colon. As in the male, the
peritoneum likewise gives a
partial investment to the
rectum, first clothing its
lateral and anterior surfaces,
then its anterior surface alone,
and finally quitting the gut Fig. 229.— Horizontal section through
altogether at a point about
three inches above the anus.
The peritoneum is now re-
flected on to the upper part
of the posterior wall of the
vagina, upon which it ascends to the posterior surface of the
uterus, which it covers completely. Reaching the fundus of
the uterus, it turns over this and descends upon the anterior
aspect of the organ. This surface of the uterus it only
invests in its upper three-fourths, and is then reflected on to
the posterior aspect of the bladder. Whilst the vagina, there-
fore, receives a partial investment from the peritoneum pos-
teriorly, it is altogether destitute of it anteriorly ; and, again,
whilst the entire posterior surface of the uterus is covered, the
theUrethra, Vagina, and Anal Canal,
a short distance above their termina-
tions. (Henle.)
Ua. Urethra. L. Levator ani.
Va. Vagina. R. Rectum.
;84
ABDOMEN
lower fourth of its anterior surface is bare, in so far as the
peritoneum is concerned. From each lateral border of the
uterus the peritoneum stretches outwards in the form of a
wide wing-like fold, called the broad ligament. This connects
the organ to the lateral wall of the pelvis and the iliac fossa.
Upon the bladder the peritoneum is carried forwards, and
at its apex is conducted to the posterior aspect of the anterior
abdominal wall by the urachus. On each side of the viscus
it extends outwards, and is continued on to the side wall of
the pelvis. An important point to notice is, that the peritoneal
membrane is much more adherent to the wall of the uterus
than it is to the wall of the bladder.
Ostium abdominale Fimbria ovarica
Ovarium
Ligamentum
Fundus Lig. ovario-
ovarii Isthmus Ampulla pelvicum
Round ligament
of the uterus
tio vaein
Vaginal wall
Fig. 230. — -The Uterus, with the Broad Ligament stretching
out from either side of it. (From Gegenbaur. )
Broad Ligament of the Uterus (ligamentum latum uteri). —
This is a wide fold composed of two layers of peritoneum
which stretches from each lateral border of the uterus to the
opposite part of the pelvic wall and iliac fossa. The superior
border of the ligament is occupied by the Fallopian tube, the
fimbriated free outer extremity of which opens into the
peritoneal cavity. Here, therefore, a continuity is established
between the mucous lining of the tube and the peritoneal
membrane. At a lower level than the Fallopian tube two
secondary folds will be observed in connection with the broad
ligament. Of these one projects backwards, and contains
between its layers the ovary and its ligament, whilst the other is
directed forwards, and contains the round ligament of the uterus.
The portion of the broad ligament which lies between the
PELVIS
5^5
Fallopian tube and the ovary is termed the mesosalpinx, whilst
the two layers which proceed from its posterior aspect to the
ovary form a very short mesentery, which receives the name
of the mesovarium.
In addition to the Fallopian tube, the ovary and its
Ureter
Obturator fossa • Ovary
Ovarian vessels
Obturator fossa .
Folds produced by nerve-cords
Pararectal fossa
Paravesical fossa
Round ligament
Obliterated
hypogastric artery
Deep epigastric artery j
Pouch of Douglas
Utero-sacral fold
FlG. 231. — Mesial section through the Female Pelvis to show the disposition
of the Peritoneum in relation to the Viscera and the Lateral Wall of
the Cavity. (Dixon and Birmingham. )
ligament, and the round ligament of the uterus, the two layers
of the broad ligament include between them other structures,
viz. — (1) the parovarium ; (2) the uteritie and ovarian vessels,
nerves, and lymphatics.
The part of the broad ligament which extends from the
upper end of the ovary to the iliac fossa in the neighbour-
hood of the external iliac vessels receives the special name
586 ABDOMEN
of the ovario-pelvic ligament, or the suspensory ligament of the
ovary. It contains between its two layers the ovarian vessels
and nerves.
Peritoneal Fossae. — The paravesical and the pararectal
fossae present in the male (p. 519) when the bladder and
rectum are empty can also be distinguished in the female.
A middle or intermediate fossa between the uterus and the
side wall of the pelvis is likewise apparent.
Recto-vaginal Pouch, or the Pouch of Douglas. — This
corresponds to the recto-vesical or recto-genital pouch in the
male. In front it is bounded by the peritoneum clothing the
upper part of the posterior wall of the vagina and the back
of the cervix uteri ; behind by the peritoneum investing the
rectum ; whilst on each side it is limited by a semilunar fold
of peritoneum, similar to the sacro-genital fold in the male,
which curves forwards and inwards from the wall of the pelvis
at the side of the rectum to the uterus. This is called the
utero-sacral fold, and it becomes continuous with its fellow of
the opposite side across the back of the uterus, at the level
of its isthmus. As it crosses the middle line on the back of
the uterus it receives the name of the torus uterini, and here
it forms the upper part of the anterior wall of the pouch of
Douglas. Between the two layers of the utero-sacral fold is
some involuntary muscular tissue. In front, this is connected
with the wall of the uterus, whilst behind, it is attached to
the sacrum and rectum.
Utero- vesical Pouch. — This is the shallow peritoneal
depression which exists between the uterus and the base of
the bladder. It is limited laterally by two slight folds of
peritoneum termed the utero-vesical folds.
False Ligaments of the Bladder.- — These are the same as in
the male bladder — viz., an anterior or superior, and two lateral.
Hypogastric Nerve Plexus. — In no respect does it differ
from that of the male {vide p. 521).
Pelvic Fascia. — For a description of the pelvic fascia and
the manner in which it should be dissected the student is
referred to p. 522. The parietal portion is identical with
that of the male, except in so far that in front where it
forms the deep layer of the triangular ligament it is traversed
by both the urethra and the vagina. The visceral portion gives
a sheath to the vagina as this pushes its way through it to
reach the surface.
PELVIS 587
Dissection. — The right innominate bone should now be removed, in
accordance with the directions given at p. 523, and the visceral layer of
the pelvic fascia followed out in its various reflections upon the viscera.
When thoroughly satisfied upon this point, remove the remains of the
fascia and clean the viscera, taking care not to injure the blood-vessels and
nerves which supply them. This dissection will be rendered easier if the
rectum and vagina be cleansed and moderately stuffed with tow. It is
better also to partially inflate the bladder, but it is a difficult matter to
retain the air when introduced ; still, it can be accomplished by sewing a
fine thread round the urethral orifice, and tightening it like a purse-string
as the blow-pipe is withdrawn.
Rectum (intestinum rectum). — A detailed account of the
rectum, as it is found in the male, is given at p. 535. It is
only necessary, therefore, to mention here the points of
difference in the female.
The rectum is separated, for a short distance, by the recto-
vaginal cul-de-sac of peritoneum from the uterus and vagina.
Below this, it is in apposition with the posterior wall of the
vagina — a layer of pelvic fascia (the recto-vaginal) alone inter-
vening. The connection between the rectal and vaginal
walls is at first very loose, but afterwards much more intimate.
This has an important bearing upon the manner in which
prolapsus uteri takes place. It should be noted that whilst
the greater part of the rectum is supported behind by the
sacrum and coccyx, there is fully an inch and a half of its
lower portion which rests upon the levatores ani and receives
support from the ano-coccygeal body (Fig. 228).
Anal Canal. — The anal canal bends downwards and
backwards about one inch and a half in front of the coccyx,
so that an angular interval is left between the gut and the
vagina — an interval to which the term perineum is restricted
by the obstetrician, and which is occupied by a pyramidal
mass of firm fibro-muscular tissue, called the pe?inea/ body
(Fig. 232).
Bladder (vesica urinaria). — The female bladder has
normally a smaller capacity than the corresponding viscus in
the male. The base, which is directed backwards, is in
relation to the neck of the uterus and the vagina. In the
female, there is no prostate surrounding its urethral orifice ;
and there are no vasa deferentia, and no vesicular seminales
in relation to its base. The relations which it presents to
the peritoneum, and the walls of the pelvis, are so similar to
those present in the male (vide p. 539) that a second descrip-
tion is unnecessary. The intimate relation, however, which the
;88
ABDOMEN
uterus presents to the superior surface of the bladder should
be noticed. The uterus rests upon it, and the two organs are
merely separated by the peritoneum which clothes both.
The position of the bladder is not quite the same as in the male. It is
placed at a lower level in the pelvis. A line carried from the inferior
margin of the symphysis pubis backwards through the urethral orifice of
the bladder strikes the posterior pelvic wall in the male at the level of the
lower part of the second sacral vertebra. In the female, such a line would
probably strike the lower border of the fifth sacral vertebra (Disse). Of
course, in making this observation we must not lose sight of the fact that
the symphysis pubis is relatively shorter in the female than in the male.
Ureters. — The pelvic portions of the ureters are slightly
Peritoneum
Retro-pubic
fatty pad
Sphincter ani
extern us
Sphincter ani
externus.
Fig. 232. — Mesial section through a Female Pelvis.
R. Rectum. B. Empty Bladder.
U. Uterus. S. Symphysis.
The uterus is antifle.xed, and, as it inclines to the right side,
the section in the upper part does not cut it into two equal and
symmetrical portions.
Note the rectal cul-de-sac above the anal canal. This is
common in multiparse.
longer in the female than in the male. They pass downwards
and forwards on the side wall of the pelvis in front of the
internal iliac artery, and then, near their termination, extend
forwards, one upon each side of the neck of the uterus. As
the ureter approaches the base of the bladder, it lies for a
very short part of its course in relation to the upper part of
the side wall of the vagina. As in the male, it pierces the
bladder wall very obliquely.
Urethra (urethra muliebris). — The urethra is the canal
along which the urine escapes from the bladder. Its walls
are always in close apposition, except when the passage is
PELVIS 589
opened by the flow of urine through it. In length, it
measures about one inch and a half, and it takes a slightly
curved course from the neck of the bladder downwards and
forwards to the vestibule, where it opens on the surface by
an aperture, called the meatus urinarius. This has been
examined in the dissection of the perineum (p. 348). On
its way to the surface the urethra passes through the two
layers of the triangular ligament, and in the interval between
these it is surrounded by the fibres of the compressor urethrse
muscle. The relation of the female urethra to the anterior
wall of the vagina is very intimate.
Uterus. — The uterus is the organ into which the ovum is
received, and in which it is retained until the foetus is fully
developed. It is placed in the interval between the rectum
and the bladder, below the general mass of the small
intestine, and above the vagina. In shape, it is pyriform or
flask-shaped, and flattened from before backwards. In length,
it is about three inches ; in breadth, at the broadest point, two
inches ; and in thickness, nearly one inch. The broader upper
end of the uterus is directed upwards and forwards, whilst its
narrow lower end looks downwards and backwards, and forms,
with the vagina, an obtuse angle, which is open towards the
pubic symphysis.
It is customary to describe the uterus as being composed
of three parts, viz. — a fundus, a body, and a neck or cervix
(Fig- 23 7>
The fundus (fundus uteri) is the rounded upper end.
The Fallopian tube enters the uterus on each side at its
upper angle, and a line drawn transversely across the organ
at this level is arbitrarily fixed upon as the limit between the
fundus and the body of the uterus. The fundus is completely
covered by peritoneum.
The body (corpus uteri) diminishes in breadth as it proceeds
downwards towards the neck. In front and behind, it is
smooth and convex, the convexity of the posterior surface,
however, being much more marked, especially in its upper
part, than that of the anterior surface. Upon each side it is
joined immediately below the entrance of the Fallopian tube,
in front, by the round ligament, and behind, by the ligament
of the ovary. Inferiorly, the body of the uterus is marked
off from the cervix by a slight constriction, which is very
apparent in the infant, but which becomes less distinct as
59Q ABDOMEN
puberty approaches, and usually disappears altogether after
parturition. This constriction is called the isthmus.
The neck or cervix (cervix uterina), about an inch in length,
is narrower than the body, and more cylindrical in form. It
projects into the upper end of the vagina, the walls of which
are attached to the uterus around it. To obtain a satisfactory
view of the cervix uteri, it is necessary to slit up the vagina
along its lateral aspect. The posterior wall of the vagina will
then be seen to ascend to a higher level upon the cervix than
the anterior wall ; or, in other words, the anterior wall of the
vagina will be observed to be shorter than the posterior
wall (Fig. 228). On the lower extremity of the cervix, which
is full, rounded, and knob-like, there is an aperture called the
os uteri externiwi (orificium externum uteri). In the virgin
this opening is small and circular, but in females who have
borne children it is usually transverse and somewhat irregular
in outline. It is bounded by two thick rounded lips. Com-
paring these, it will be noticed that the anterior lip is the
thicker of the two, whilst the posterior is the longer. Although
the anterior lip is the shorter, it should be noted that, on
account of the oblique position of the uterus, it is placed at a
lower level in the vagina. The greater length of the posterior
lip is due to the fact that the wall of the vagina passes higher
up on that aspect of the uterus. The part of the cervix
which projects into the vagina is called the portio vaginalis ;
the part above is termed the portio supravaginal.
As the mucous membrane which lines the vagina passes
from its anterior wall on to the anterior lip of the os uteri, it
forms a shallow angular recess between the two, called the
anterior fornix. The same is seen behind in connection with
the posterior lip of the os uteri, but, owing to the higher
attachment of the posterior vaginal wall, the posterior fornix is
very deep. A most important relation should be made out
at this stage, viz., that when the finger is placed in the
posterior fornix it is merely separated from the peritoneum
lining the pelvic cavity by the posterior vaginal wall (Fig. 228).
This is due to the fact that the recto-vaginal cul-de-sac of
peritoneum descends so as to cover the upper part of the
posterior vaginal wall.
The relations of the uterus should next be studied.
Posteriorly, it is invested completely by peritoneum, and is
separated from the rectum by the recto -vaginal cul-de-sac.
PELVIS 591
Within this peritoneal pouch there are always more or less of
the pelvic colon and a few coils of small intestine. Anteriorly.
it is covered in its upper three-fourths by peritoneum, and is
in apposition with the bladder. Below the utero-vesical
reflection of peritoneum the anterior surface of the uterus is
directly connected with the base of the bladder by some loose
areolar tissue. Laterally, the uterus is connected with the
broad ligament. Further, on either side of the neck of the
uterus and the upper part of the vagina, there is a mass
of loose fatty tissue containing large vessels. This is termed
the parametrium, and it is prolonged upwards on the side of
the uterus for some distance between the layers of the broad
ligament.
Position of the Uterus. — In women who have borne no
children (nulliparae) and in whom the bladder and the
rectum are both empty, the uterus is normally strongly ante-
flexed and anteverted. When we say that the uterus is ante-
flexed, we mean that it is bent forwards upon itself at the
isthmus, so that the body and the cervix meet at an angle
which is open to the front. This forward flexion of the uterus
depends upon two circumstances, viz. — (1) upon the greater
pliability of the body as compared with the firmer consistence
and greater rigidity of the cervix; and (2) upon the fact that
the cervix is more or less held in position by its attachments
to the anterior vaginal wall and the base of the bladder in
front, and to the posterior vaginal wall behind. By the term
" anteversion," we mean that the whole uterus — both body
and cervix — is inclined forwards so as to form an angle of
greater or less magnitude with the vertical axis of the trunk.
In this position of the uterus the coils of the small intestine
and a loop of the pelvic colon rest upon its posterior surface,
whilst its anterior surface is supported by the bladder. It is
very rare indeed that a coil of small intestine is found between
the uterus and the bladder in the utero-vesical pouch of
peritoneum. In multiparas (women who have borne children)
the anteflexion of the uterus is not so marked as it is in
nulliparae.
But the uterus possesses a great degree of mobility, and
consequently we find that its position is constantly liable to
change. Intra-abdominal pressure, and distension of the
bladder or rectum, are the chief agencies at work in produc-
ing these effects. Every breath that is taken, ever}' move-
592
ABDOMEN
ment of the body, is followed by a slight alteration in the
position of the uterus. When the bladder fills, the uterus
is raised with it ; the anteflexion and the anteversion become
less marked, and, in cases of hyper-distension of the bladder,
the uterus may assume an erect position or even come to lie
in the same line as the vagina. With this change of position
Fundus of the uterus
Isthmus of the Fallopian tube
Fallopian tube
Ampulla of
Fallopian tube
Fimbriated
end of Fal-
lopian tube
B. Body of the uterus.
C. Cervical canal.
'V. Vagina.
H. Hymen.
U. Urethral opening.
V. Vestibule.
X. Xympha.
L.M. Labium maj us.
P". Parovarium.
Pudendal cleft
Fig. 233. — Diagram of the Vulva, Vagina, and the Uterus, with
its Appendages. (Symington.)
the relation of the uterus to the rectum becomes more
intimate, through the forcing of the small intestine out of the
pouch of Douglas. When the rectum becomes distended the
uterus is pushed forwards and usually to the right side.
Under no circumstances is it usual to find the uterus
occupying an accurately median position. It would appear that
it is more frequently inclined to the right than to the left side.
Vagina. — The vagina is the passage which leads from the
uterus to the vulva. In length it is about three inches, and in
PELVIS
593
the empty condition of the bladder and rectum it pursues a very
nearly straight course from above downwards and forwards.
In the erect posture of the body its long axis may be said to
be nearly parallel to the plane of the pelvic brim. Superiorly,
its walls are firmly attached to the substance of the uterus
around its neck, upon which it ascends to a higher level
behind than in front ; on account of this, the cervix uteri has
the appearance of piercing its anterior wall. The vagina is
wider in the middle than at either end, and the anterior and
posterior walls are closely applied to each other, so that in
no respect can the vagina be regarded as an open tube or
canal. In section, therefore, it appears simply as a transverse
Ostium abdominale Fimbria ovarica
Ovarium
Ligamentum
ovario-
a pelvicum
Round ligament
of the uterus
Portio vaginalis
Vaginal wall
Fig. 234. — The Uterus, with the Broad Ligament stretching
out from either side of it. (From Gegenbaur. )
or longitudinal slit, according to the direction in which it is
divided (Figs. 228 and 229).
Posteriorly, the upper end of the vagina is in relation to
the bottom of the recto-vaginal pouch of peritoneum. Below
this it is in apposition with the rectum. Still lower down, it
is separated from the anal canal by an angular interval, which
is occupied by the perineal body. Anteriorly, the vagina is
related to the base of the bladder and to the urethra — indeed,
the latter almost appears to be embedded in its wall. Upo?i
each side of the vagina, the levator ani muscle descends and
gives it support, whilst its lower end is clasped between the
two vestibular bulbs and is embraced by the sphincter vaginae.
Close to the neck of the uterus the ureter is related to the
vagina on each side for a very limited part of its course,
vol, I — 38
594
ABDOMEN
Ovaries. — The ovaries are two small solid bodies contained
within the posterior secondary folds of the broad ligaments.
Each ovary is oval or oblong in figure, slightly compressed
from side to side, and having a size somewhat similar to that
of a pigeon's egg.
The ovary presents two flattened surfaces, two extremities
or poles, and two borders. Its natural or typical position
can only be studied in young women who have borne no
children. When pregnancy occurs the ovaries become dis-
placed, and it is questionable if they ever regain their original
place within the pelvis. In the young virgin and in the erect
posture of the body the ovary lies with its long axis vertical.
It occupies a peritoneal fossa on the posterior part of the
side wall of the pelvis, immediately below the external iliac
vessels (Fig. 235). This recess is termed the fossa ovaiica.
From the upper pole of the ovary the ovario-pelvic fold of
peritoneum passes outwards to the wall of the pelvis. To the
same extremity the mouth of the Fallopian tube is attached
by one of its fimbriae ; from the latter connection the term
tubal pole (extremitas tubaria) is frequently applied to the
upper end of the ovary. The lower extremity is connected
with the uterus by a round cord-like structure, the ligament of
the ovary, which is included between the two layers of the
broad ligament. This end of the ovary is consequently some-
times called the uterine pole (extremitas uterina). The two
surfaces of the ovary look outwards and inwards, and the two
borders are directed forwards and backwards. The anterior
border is thinner and straighter than the posterior border, and
is very commonly called the attached border or the hilum. The
term " attached " is applied to it because it is along this
margin that the two layers of the broad ligament which
enclose the ovary leave it. Everywhere else it presents a free
surface. The name of "hilum," on the other hand, is given
to this margin because the vessels, nerves, and lymphatics
enter and leave the organ along its whole length. The
posterior border of the ovary is free, and looks slightly inwards
towards the rectum as well as backwards. The Fallopian
tube in the natural position of the pelvic organs encircles the
greater part of the circumference of the ovary.
The ovary is completely surrounded by peritoneum, except
along its hilum, where the vessels enter and to which the mes-
ovarium is attached. The membrane, however, does not present
PELVIS
595
so highly polished an appearance as in other parts of the
abdominal cavity. This is due to a change in the form of the
surface epithelium, which is placed over the ovary. Before
puberty the surface of the ovary is smooth and uniform.
After this period, however, it becomes scarred and puckered
from the breaches which are made by the escape of the ova
from the Graafian follicles.
Parovarium, or the Organ of Rosenmuller (Epoophoron).
External iliac vessels
Ligament of ovary
Round ligament
of uterus
Fig. 235. — Left Side Wall of Female Pelvis to show position of the Ovary.
The ovary is much scarred through the shedding of ova.
— This structure is of interest because it is the representative
of the epididymis in the male. It is somewhat triangular
in form, and will be discovered by an attentive examination
of the mesosalpinx or that portion of the broad ligament of
the uterus which stretches between the ovary and the Fallopian
tube. Its apex is directed towards the former, and its base
towards the latter ; but it lies free between the two layers of
the ligament, and is not connected with either. In structure
it consists of a number of tubules which radiate from the apex
of the organ and join a longitudinal tube (the homologue of
596
ABDOMEN
the duct of Gartner in the cow, etc.), which extends along
its base.
A few isolated tubules can also be seen in the mesosalpinx of the child
at a point somewhat nearer the uterus. These constitute the paroophoron
or a rudimentary structure which represents the paradidymis in the male.
Fallopian Tubes or Oviducts (tubae uterinae). — These are
two tubes which have as their function the conveyance of
the ova or eggs from the ovary to the uterus. Each duct is
about four inches long, and is contained within the superior
free border of the broad ligament of the uterus. Its inner
extremity pierces the uterus at its superior angle, whilst its
Parovarium
Fallopian .
tube-
Ligament of.
the ovary
Ostium
abdominale
r Fimbria ovarica
FlG. 236. — The Ampulla and Fimbriated End ol the
Fallopian Tube ; the Ovary ; and the Parovarium,
i From Gegenbaur, modified. 1
outer end, when the broad ligament is put on the stretch,
is situated about an inch beyond the ovary and opens into
the peritoneal cavity by a constricted orifice {pstiu?n ab-
dominafe), surrounded by numbers of fringe-like processes,
called fimbrice. By one of these fimbriae, termed the ovarian
fimbria (fimbria ovarica), it is attached to the tubal pole of the
ovary. The calibre of the Fallopian tube is by no means
uniform. As it is traced outwards from the uterus it is at first
extremely narrow. This portion is called the isthnius (isthmus
tubae uterinae). In the neighbourhood of the ovary it dilates
considerably, and receives the name of the a??ipulla (ampulla
tubae uterinae). The ovarian fimbria is longer than the others :
it is attached along its whole length to the broad ligament,
PELVIS 597
and shows on its surface a gutter-like groove leading from
the constricted mouth of the tube to the ovary (Fig. 236).
In the undisturbed position of parts the Fallopian tube
proceeds horizontally outwards on the pelvic floor. It then
turns vertically upwards along the hilum or attached border
of the ovary, and, gaining the tubal pole, it bends upon
itself and turns downwards upon the posterior free border
and the inner surface of the ovary, both of which it in great
part covers. It may, therefore, be considered to consist of
three parts : — (1) the first in relation to the floor of the pelvis ;
(2) the second in relation to the anterior border of the ovary;
(3) the third in relation to the posterior border and the inner
surface of the ovary.
Round Ligament of the Uterus (ligamentum teres uteri). —
The round ligaments are two cord-like bands largely composed
of involuntary muscular fibres, which are attached to the body
of the uterus immediately in front of and a little below the
entrance of the Fallopian tube — one on each side. From
this, each ligament is directed outwards and forwards between
the layers of the broad ligament and in front of the oviduct,
to the internal abdominal ring. It has already been examined
within the inguinal canal. In the child the peritoneum may,
in rare cases, be prolonged along with it into this canal in
the form of a tubular process termed the " Canal of Nuck."
Later on this becomes obliterated.
The ligament of the ovary which attaches the lower end of the ovary to
the uterus represents the upper part of the foetal gubernaculum in the
male ; whilst the round ligament represents the lower part of the same
structure.
Pelvic Blood Vessels.
The manner in which the blood vessels of the pelvis
should be dissected is described at p. 550. In the female
three additional arteries will be found, viz. —
2. The vaginal', }branches of the internal iliac.
3. The ovarian, from the abdominal aorta.
Uterine Artery (arteria uterina). — The uterine artery
springs from the anterior division of the internal iliac artery,
and proceeds downwards and inwards to the neck of the uterus.
At this point it gives several small branches to the vagina and
bladder, and, changing its direction, extends upwards in a
598 ABDOMEN
tortuous manner along the lateral border of the uterus and
between the two layers of the broad ligament. Reaching
the fundus, it sends several twigs outwards into the broad
ligament ; of these, one accompanies the round ligament,
another goes with the Fallopian tube, and several proceed to
the ovary, and anastomose with twigs from the ovarian artery.
Whilst in contact with the lateral border of the uterus, the
uterine artery gives numerous branches to this organ.
Vaginal Artery (arteria vaginalis). — The vaginal artery
also springs from the anterior division of the internal iliac,
but it is not unusual for it to arise in common with the uterine
artery, or the middle hemorrhoidal artery. It is distributed
to the vagina, and sends twigs to the rectum and bladder.
Ovarian Artery (arteria ovarica). — The course which
this vessel takes within the abdomen proper is described at
p. 504. When it arrives at the pelvis, it crosses the upper
parts of the external iliac vessels and insinuates itself between
the two layers of the broad ligament of the uterus, where
this forms the ovario-pelvic fold. It is highly tortuous, and
runs along the anterior border of the ovary, and from thence
onwards to the fundus of the uterus, where its terminal
branches anastomose with the uterine artery. In addition to
the branches which enter the hilum of the ovary it gives
others to the Fallopian tube and to the round ligament of
the uterus.
The other arteries of the female pelvis correspond with
those of the male, and therefore it is needless to repeat the
description which will be found at p. 551.
Veins of the Pelvis. — Very few facts require to be added to
those which are given regarding the veins of the male pelvis
(p. 554). Of course there is no prostatic plexus of veins
in the female, and therefore the dorsal vein of the clitoris
joins the vesical plexus.
A bulky uteri?ie venous plexus is formed on each side of the
uterus between the two layers of the broad ligament. This
enters into the formation of the parametrium, and from its
lower part the blood is drained away by a uterine vei?i which
opens into the internal iliac vein.
A vagi?ial plexus of veins is likewise formed on each side
of the vagina, and from its upper part the vaginal vein
proceeds which carries the blood to the internal iliac vein.
The veins which issue from the hilum of the ovary form a
PELVIS 599
pampiniform plexus between the layers of the broad ligament.
From this, two ovarian veins issue which accompany the
ovarian artery. These ultimately unite, and the vein thus
formed ends in a manner similar to the spermatic veins in
the male.
Pelvic Diaphragm.
This is described at p. 555. The dissector should note,
however, that the fibres of the levator ani muscle pass down-
wards upon the lateral aspect of the vagina and give it
support (Fig. 229).
Nerves of the Pelvis.
Very little requires to be added to what has already been
said regarding the nerves of the male pelvis (p. 557). There
is no prostatic plexus \ but a vaginal plexus, an ovarian plexus,
and a titerine plexus are present in addition to those men-
tioned in the male.
The uterine plexus proceeds from the pelvic plexus. It
ascends between the two layers of the lateral ligament along
with the uterine artery, and is distributed upon both aspects
of the organ.
The vaginal plexus is an offset from the pelvic plexus, and
the nerves which compose it are mainly derived from the
visceral branches which enter the pelvic plexus from the
sacral nerves.
The ovarian plexus is derived from the aortic and renal
plexuses, and, accompanying the artery of the same name, is
distributed to the ovary.
Coccygeal Body. — Vide p. 561.
Removal of Viscera. — The viscera should now be removed from the
pelvic cavity. Begin by cutting the various nerves and vessels which enter
them, the levator ani and the anterior true ligaments of the bladder. Then
carefully divide the parts which hold the urethra and vagina to the arch
of the pubis. Lastly, separate the rectum from its connections with the
sacrum and coccyx.
The obturator intemus and pyriformis muscles should now be studied.
They are described at p. 562.
The viscera should next be separated from each other ; but the vagina
must be left attached to the uterus, and the urethra to the bladder.
Coats of the Rectum and Anal Canal. — The coats of these
portions of the intestinal canal are identical in both sexes.
600 ABDOMEN
The student may, therefore, refer to p. 563, where the wall
of the male rectum and anal canal is described.
Bladder. — Particulars regarding the coats of the bladder
may be obtained by turning back to p. 565. In slitting open
this viscus the urethra should be laid open along its upper
surface at the same time.
Urethra. — The external meatus is the narrowest part of
this tube. As the urethra is traced upwards, it will be seen
to expand before joining the neck of the bladder, and close
to the meatus its floor will be noticed to be somewhat
depressed so as to form a slight hollow.
Dissection. — The uterus with its appendages should now be laid upon
its posterior surface on a block. The round ligaments and the ligaments
of the ovaries should be isolated and their attachments defined, and then
the uterus may be opened by a longitudinal mesial incision through the
anterior wall, extending from the fundus to the os uteri externum. A
transverse cut should also be made outwards from the upper end of this
incision towards the entrance of each Fallopian tube. The cut edges may
now be pared so as to extend the view of the interior of the uterus.
Wall of the Uterus. — The rou?id ligament will now be seen
to be attached to the body of the uterus immediately in front
of and a little below the entrance of the Fallopian tube.
The ligament of the ovary, a much more slender band, is a
fibrous cord containing some muscular tissue derived from the
wall of the uterus. It extends from the lower uterine pole of
the ovary to the body of the uterus, which it joins immedi-
ately behind and a little below the entrance of the Fallopian
tube. In all its length, it is enclosed between the two layers
of the broad ligament.
The wall of the uterus is very thick, and presents three
well-marked coats, viz., a serous or peritoneal, a muscular,
and a mucous. The serous coverifig has already been fully
studied. The muscular part of the wall constitutes its chief
bulk. It is composed of involuntary muscular tissue, with a
considerable admixture of areolar tissue. It is not equally
thick throughout. Thus it becomes distinctly thinner towards
the angles or points where the Fallopian tubes open. The
mucous lining will be studied after the interior of the organ
has been examined.
Interior of the Uterus (cavum uteri). — The cavity of the
uterus is much smaller than would be expected from an
inspection of the exterior of the organ. It is subdivided
PELVIS
601
Opening of
Fallopian tube
Cavity of body
of uteris
arbitrarily into an upper part, which occupies the body, and
a lower or cervical part, which occupies the cervix.
The upper portion is the larger of the two, and is triangular
in form. The anterior and posterior walls are in contact
with each other, and the sides of the triangle are incurved,
the base being directed upwards. At the two angles of
the base are the constricted openings of the Fallopian tubes.
The lower cervical portion is fusiform or spindle-shaped in
form, being also slightly compressed from before backwards.
Above, it is somewhat constricted, and at the junction of
the body with the cervix of the uterus it becomes continuous
with the upper triangular part of the cavity. This narrow
opening is termed the os
uteri internum (orificium
internum uteri). Below,
the cavity of the uterus
opens, into the vagina
by the os uteri externum.
Mucous Membrane of
the Uterus. — The dis-
sector will not fail to
note a striking difference
between the mucous lin-
ing of the uterus in the
triangular cavity of the
body and in the fusiform
cavity of the cervix. In
the former it is smooth
and even, and tightly bound down to the subjacent muscular
tissue. In the cervix it presents a remarkable disposition,
which, from its appearance, has been termed the arbor vita.
This consists of a series of prominent folds or rugae arranged
in a definite manner. Thus, there is an anterior and posterior
median fold or raphe, and from this secondary folds branch
off and pass obliquely upwards and outwards. The arbor
vitae is more marked upon the anterior than upon the
posterior wall.
The student should look between the folds of the arbor
vitae for ovula Nabothi. These are minute vesicles filled with
a yellowish liquid. They result from the distension of
certain of the tubular glands in the mucous membrane,
through obstruction of their mouths.
Isthmus of the uterus
Cervical canal
Os uteri externum
Fig. 237. — Interior of the Uterus. (Luschka. )
602 ABDOMEN
Fallopian Tubes. — The Fallopian tube has an external
serous, an intermediate muscular, and an internal mucous
coat. The aperture by which it opens into the uterus is
exceedingly small, and will barely admit a bristle. The
expanded ampulla, however, may be opened up. In this
part of the tube the mucous membrane will be seen to be
arranged in longitudinal folds. To obtain a proper idea of
the fimbriae which surround the ostium abdo7?ii?iale, the tube
should be immersed in water, when the fringes will float out
and separate from each other.
Coats of the Vagina. — Outside the mucous lining there
is a thin layer of erectile tissue, and spread over this the
proper muscular coat of the vagina. The mucous lining will
be observed to present special peculiarities. Two well-marked
median and longitudinal folds extend upwards, one upon the
anterior and the other upon the posterior wall. These are
termed the columncz rugarum, and from each side they send
off numerous transverse rugae, which are arranged so that
those on the anterior wall fit in between those on the posterior
wall. These folds are best marked near the vaginal orifice,
and are absent at the upper end of the canal.
Pelvic Articulations.
These are described at p. 575. In the later months of
pregnancy the ligamentous tissues of the various pelvic joints
become softened, thickened, and infiltrated. The pelvic
bones are thus partially separated from each other, and the
width of the pelvic circle is increased.
INDEX
603
INDEX
Abdomen, 322
Abdominal cavity, 404
boundaries, 404
contents, 408
peritoneum, 430
relations between thoracic and
abdominal organs, 423
subdivisions, 407
Abdominal ring, external, 365, 396
internal, 381, 396, 397, 398
tunic, 360
wall, 357
adaptation to viscera, 430
arteries, 383, 500
cutaneous nerves, 361
vessels, 363
fascia, 359, 381, 50S
muscles, 363, 508
nerves, 373, 510
posterior, 500, 508, 510
surface anatomy, 357
surgical anatomy, 396
Alcock's canal, 329, 341, 528
Ampulla of Fallopian tube, 596, 602
of vas deferens, 549
Ampullae lactiferi, 21
Anal canal, 425, 538, 564, 587, 599
valves, 565
Ano-coccygeal body, 331, 535, 538,
587
Antecubital fossa, 74
Aorta, abdominal, 501
Aortic opening of diaphragm, 499.
500
plexus, 450, 470
Aponeurosis, brachial, 63
of external oblique, 365, 396
of internal oblique, 371
of transversalis, 375
Appendices epiploicae, 409, 456
Arbor vitae, 601
Arch, anterior carpal, 92
coraco-acromial, 50, 82
crural, 203
deep, 203
palmar, deep, 122. 123
superficial, 109, 123
plantar, 285, 286
Arcus tendineus, 528, 529
Arches of foot, 311, 320
Areola mammae, 19
Arm, 55
antecubital fossa, 74
back of, 76
cutaneous nerves. 58
fascia, 63
front of, 55
osteo- fascial compartments. 65,
76.
superficial veins, 62
surface anatomy. 55
Arterial anastomosis of ankle, 271
of back of thigh, 189
crucial, of thigh, 172
of elbow, 132
of knee, 290
of scapula, 54
Artery or Arteries, acromial, 30, ^^
anastomotic, of brachial, 70, 76,
81, 132
of femoral, 177, 215. 216. 220.
290
of appendix. 447
articular, of knee, 178, 1S3. 1S4.
220, 259, 290. 291. 204,
295. 297
of hip, 229
axillary, 24. 2S, 31
brachial, 65, 66, 74
of breast, 20
605
6o6
INDEX
Artery or Arteries, of bulb of penis,
339, 340, 343, 356
caecal, 447
calcaneal, 265, 267, 272
capsular, 496, 502, 503
carpal, radial, 92, 134
ulnar, 98, 99
cervical, superficial, 11
circumflex, external, 173, 189,
209, 220, 227, 229
anterior, 25, 28, 35, 48
iliac, deep, 385, 506
superficial, 193, 208, 229,
363
internal, 167, 171, 189
of thigh, 209, 227, 229
posterior, 24, 28, 35, 47
clavicular, 30, 33
coccygeal, 168
coeliac axis, 458, 459, 502
colic, left, 447, 450
middle, 447
right, 447
comes nervi ischiadici, 168
communicating, anterior, 102, 103
tibial, 265, 267
coronary, of stomach, 459
of corpus cavernosum, 342, 356
cremasteric, 373, 384, 389
cystic, 460, 461
digital, of foot, 286
of hand, 107, 109, ill, 122
dorsalis clitoridis, 356
indicis, 134, 135 *
pedis, 248, 251, 252
penis, 342, 343, 404
pollicis, 134, 135
scapulae, 35, 46, 53
epigastric, deep, 363, 382, 383,
384, 397, 398, 402, 506
superficial, 192, 208, 229, 363
superior, 363, 385, 497, 500
femoral, 206, 208, 210, 214, 215,
229, 505
fibular, superior, 265
gastric, 459
short, 461, 462
gastro-duodenal, 460
gastro-epiploic, 461
gluteal, 167, 173, 553
hemorrhoidal, 329, 449, 551,
552, 553
hepatic, 459, 460, 461
humeral, 33
hypogastric, 551
infrascapular, 54
Artery or Arteries, infraspiuous, 53
ileo-coecal, 447
ileo- colic, 446
iliac, 553
common, 504
external, 505
_ internal, 505, 550
ilio-lumbar, 553
interosseous, of foot, 254
of hand, 102, 122, 134
anterior, 99, 133
common, 98, 99
posterior, 99, 128, 130
intestinal, 446
lumbar, 6, 383, 500, 502, 504.
515, 553
magna hallucis, 286
malleolar, 251, 252, 272
mammary, external, 34
median, 100, 102
mesenteric, inferior, 448, 502
superior, 444, 502
metatarsal, 253, 254
musculo-phrenic, 385, 500
nutrient, of bones, 69, 102, 228,
266, 270
obturator, 207, 234, 402, 533,
55i, 552
oesophageal, 459
ovarian, 502, 504, 598
pancreatic, 461
pancreatico-duodenal, 446, 460
pectoral, 29, 30, 33
perforating, of foot, 286
of hand, 122, 135
of internal mammary, 18
of profunda femoris, 165, 188,
227, 228, 229
perineal, superficial, 326, 331,
332, 342, 350
transverse, 332, 342, 350
peroneal, 248, 254, 267, 270, 271,
272
phrenic, inferior, 502
plantar, external, 276, 277, 278
internal, 275, 277
popliteal, 176, 181, 264
princeps pollicis, 123
profunda brachii, inferior, 68, 81,
132
superior, 68, 75, 78, 79, 81,
132
femoris, 208, 225, 226
of ulnar, in
pubic, of deep epigastric, 402
of obturator, 552
INDEX
607
Artery or Arteries, pudic, deep ex-
ternal, 208, 212, 229
internal, 167, 169, 329, 339.
340, 341, 356, 551. 552
superficial external, 192, 208,
229, 363
pyloric, 459, 460
to quadratus femoris, 168
radial, 91, 122, 134
radialis indicis, 122, 123
recurrent, of deep palmar arch, 122
interosseous, 131
radial, 76, 92, 132
tibial, 251, 265, 290. 291
ulnar, 76, 98, 132
renal, 488, 502, 503
sacral, lateral, 551, 553
middle, 502, 554
scapular, posterior, 12, 54
sciatic, 164, 167, 168, 189, 551,
552
sigmoid, 450
spermatic, 389, 390. 501, 502, 503
splenic, 459, 461
subcostal, 516
subscapular, 13, 25, 28, 34, 53, 54
superficial volar, 92
suprascapular, 11, 53, 54
supraspinal, 13
supraspinous, 53
sural, 185
tarsal, 253, 254, 272
thoracic axis, 24, 30, 33
thoracic, alar, 33, 34
long, 24, 33, 34
superior, 25, 31, 33
tibial, anterior, 248, 250, 256, 264,
265, 272
posterior, 264, 265, 272
transversalis colli, n
ulnar, 97, 109
uterine, 597
vaginal, 597, 598
of vas deferens, 390, 552
vesical, 551, 552
Articulations. See Joints
Axilla, 13, 23
boundaries, 23
contents, 24
fascia, 25, 26
folds, 15, 22, 23, 24
lymphatic glands, 25. 26
nerves, 24
structures passing from neck, 36
surface anatomy, 15
surgical anatomy, 25
Axilla, vessels, 24. 27. 31
Axillary sheath, 31. 32
Back, 2
cutaneous vessels and nerves, 4
fascia, 3
intermuscular spaces, 9
muscles to upper limb, 6
structures beneath trapezius, 10
surface anatomy. 1
Band, ilio-tibial, 199, 219, 235, 294
pudendal, of sacral plexus, 558
sciatic, of sacral plexus, 558
Bartholin's gland, 349, 356
Bertin, columns of, 494
Bile-ducts, 469, 477, 483
Bile-papilla, 477
Bladder, 518, 539, 583
coats, 565, 600
distended, 542
empty, 540, 542
female, 587
in new-born, 545
orifices, 541, 545, 567
peritoneal relations, 543
triangle at base, 549
trigone,- 568
Brachial aponeurosis, 63
plexus, 36
Breast, 18
Brunners glands, 477
Bulb of penis, 335, 402
of vestibule, 352
Bursa intertubercularis, 87
over ischial tuberosity, 325
patellar, 201
subacromial, 47
subscapular, 53, 55, 84, 8j
under gastrocnemius, 263, 295
gluteus maximus, 165
minimus, 174
ilio-psoas, 235, 237
ligamentum patellce, 297
sartorius, 188, 233, 259
semimembranosus, 177
Buttock. See Gluteal region
Crecum, 409, 426, 444
Calices of kidney, 493
Canal of Alcock, 329, 341. 528
anal, 425, 538, 564, 587, 599
crural, 206, 396, 401. 402
of epididymis, 395
of Hunter, 213
inguinal. 3S2. 396
of Nuck, 597
6o8
INDEX
Canal, portal, 485
pyloric, 421
of Wirsung, 468
Capsule, of Glisson, 484, 485
suprarenal, 486, 490, 494
Caput gallinaginis, 570
Cardiac orifice, 418, 422
Carpal arch, anterior, 92
Cartilages, semilunar, 298, 302
Carunculas myrtiformes, 348
Caudate lobe of liver, 480, 481
Central point of perineum, 336, 350,
351
tendon of diaphragm, 496, 499
Cervix uteri, 590
interior, 601
portio supravaginalis, 590
vaginalis, 590
Cleft, natal, 158
pudendal, 346
Clitoris, 345, 347, 353
Coccygeal body, 561, 599
Coeliac plexus, 459, 470, 471
Colliculus seminalis, 570
Colon, ascending, 425, 426
descending, 425, 428
iliac, 409, 425, 429
pelvic, 425, 429, 518, 535, 582
transverse, 409, 425, 427
Columnar recti, 565
rugarum vaginas, 602
Columns of Bertin, 494
of Morgagni, 565
Commissure, anterior, of vulva, 346
Congenital hernia, 400
Coni vasculosi, 395
Conjoined tendon, 370, 372, 376,
396, 399
Cooper, ligaments of, 20
Coraco-acromial arch, 50, 82
Cord, gangliated, of sympathetic,
500, 509, 510, 561
lumbo-sacral, 500, 511, 557
spermatic, 358, 369, 372, 381,
382, 387, 389, 396
Corona glandis, 403
Coronary plexus, 470, 471
Corpora cavernosa, 333,. 353, 402,
574
Corpus spongiosum, 334, 335, 402,
575
Cortex of kidney, 494
of suprarenal body, 496
Costal zone, 407
Costo-coracoid membrane, 29
Cowper's gland, 340, 341, 573
Crest of urethra, 570
Crucial anastomosis of thigh, 179
Crura clitoridis, 353
of diaphragm, 496, 498
of external abdominal ring, 367
penis, 334, 402
Crural arch, 203
deep, 203
canal, 206, 396, 401, 402
ring, 206, 207, 401
septum, 206, 401
Crypts of Lieberkiihn, 455
Cystic duct, 469, 483
plexus, 471
Diaphragm, 404, 496
central tendon, 499
foramina, 499
pelvic, 517, 555, 599
Diaphragmatic plexus, 470, 471
Digital fossa of peritoneum, 397
of tunica vaginalis, 393
Diverticulum Meckelii, 425
Dorsal expansion of extensor tend-
ons, 137, 250
Douglas, fold of, 379
pouch of, 586
Duct, biliary, 469, 477, 483
cystic, 469, 483
ejaculatory, 548, 549, 557, 571
hepatic, 469, 484
pancreatic, 468, 477
prostatic, 571
thoracic, 499, 507
Ductus venosus, 478
Duodenal fossae, 444
Duodenojejunal flexure, 425
Duodenum, 424, 463
coats, 476
suspensory muscle, 466
Ejaculatory ducts, 537, 548, 549,
571
Elbow, 55
antecubital fossa, 74
arterial anastomoses, 132
joint, 139
superficial veins, 62
surface anatomy, 55
surgical anatomy, 62
Epididymis, 392, 395
Epigastric plexus, 470
region, 408
Epoophoron, 595
Extensor tendons, of fingers, 136
of toes, 249
INDEX
609
Fallopian tube, 584, 596, 602
Fascia of abdomen, 359
anal, 328, 533
of arm, 63
axillary, 25
of back, 3
bicipital, 63, 64, 72
of Camper, 192, 359
of Colles, 325, 326, 344, 360
cremasteric, 372, 386, 398
cribriform, 194, 195, 200
of foot, 245, 272
of forearm, 90, 91, 124
of hand, 105, 107
iliaca, 200, 204, 381, 401, 508, 526
infundibuliform, 381, 386, 398, 399
intercolumnar, 366, 386, 398, 399
lata of thigh, 185, 194, 198, 219
of leg, 245, 261, 264
lumbar, 374
obturator, 528
palmar, 107, 108, 123
pectoral, 16, 20, 25
pelvic, 328, 517, 522, 524, 525.
572, 586
of perineum, 324, ^^7, 349
plantar, 274, 311
popliteal, 176
of popliteus, 26S
of psoas and iliacus, 508
pyriformis, 526, 527
of quadratus lumborum, 508
rectal, 532
of Scarpa, 192, 359
semilunar, 64, 72, 74
of shoulder, 43
of sole, 272
spermatic, 364, 366, 381, 386,
398, 399
of thigh and buttock, 159, 162,
185, 191, 194, 198, 219
transversalis, 204, 379, 381, 398,
399, 401, 509
triangular, 370
Femoral hernia, 206, 401
sheath, 203, 211, 401, 509
Fibro-cartilage, triangular, of wrist.
143, 146, 147
Fibro- cartilages, semilunar, 297.
298, 302
Fimbria, ovarian, 596
Fimbria; of Fallopian tube, 596, 602
Fingers, extensor tendons, 136
flexor sheaths and tendons. 114,
116, 123
movements, 154
VOL. I 39
Fingers, surgical anatomy, 123
Fissure of ductus venosus, 479
longitudinal, of liver, 478
transverse, of liver, 480
umbilical, 478
urogenital, 346
Flexor tendons of foot, 281, 282
of hand, 115, 117
sheaths of, 114, 116, 123, 281
Flexure, duodeno-jejunal, 425, 463
hepatic, 425, 427
splenic, 425, 427
Fold, axillary, 15, 22
of Douglas, 379
of nates, 158
ovario-pelvic, 594
sacro-genital, 519, 521
utero-sacral, 586
Foot, arches, 311, 320
cutaneous nerves, 243, 272. 280
dorsum, 243
fascia, 245, 272
intermuscular septa, 274
joints,
;n
sole, 272. See also Sole
surface anatomy, 241
synovial cavities, 319
Foramen of Winslow, 434, 436, 481
Forearm, 88
back and outer border, 124
cutaneous nerves, 58, 61, 88
deep anterior structures, 101
deep posterior structures, 128
fascia, 90, 91, 124
front and inner border, 90
muscles, anterior superficial, 93
posterior superficial, 125
superficial veins, 62, 88
surface anatomy, 57
Fornix of vagina, 590
Fossa, antecubital, 74
digital, of peritoneum, 397
of tunica vaginalis, 393
duodenal, 444
for gall-bladder, 480
genital, 521
ileo-caecal, 444
ileo-colic, 444
infraclavicular, 14
infrasternal, 15
intersigmoidea, 444
ischio-rectal, 327
navicularis, 346, 572
ovarica, 594
paraduodenal, 444
pararectal, 519, 521, 586
6io
INDEX
Fossa, paravesical, 519, 586
retro-colic, m
for vena cava inferior, 483
Fossae, peritoneal, 397, 444, 519,
586
Fourchette, 346
Frenula of ileo-caecal valve, 457
Frenulum clitoridis, 346
pudendi, 346
Frenum preputii, 403, 572
Fundus of stomach. 418
uteri, 589
Furrow, iliac, 158
Gall-bladder, 409, 414, 483
fossa for, 480
Gangliated cord of sympathetic. 500,
509, 510, 561
Ganglion impar, 561
semilunar, 470 ♦
Gastro-colic omentum, 431
Gastro-epiploic plexus, 471
Gastro-hepatic omentum, 420, 431,
432> 436> 439
Gastro-splenic omentum, 417, 431,
436, 440
Genital fossa, 521
Glans clitoridis, 348, 353
penis, 403
Glisson's capsule, 484, 485
Globus major, 392, 395
minor, 392, 393, 395
Gluteal region, 157
cutaneous nerves, 159
fascia, 159, 162
parts beneath gluteus maximus.
165
parts beneath gluteus medius,
172
parts beneath gluteus minimus,
174
surface anatomy, 158
sulcus, 158
Gubernaculum testis, 389
Hemorrhoidal plexus. 561
venous, 554
Ham, 175
Hand, 88, 103, 133
cutaneous nerves. 88. 89. 100. 107
dorsum, 88, 133
extensor tendons, 136
fascia, 105, 107
flexor tendons, 94, 97, 114
joints, 149
Hand, palm, 103. See also Palm
Hand, superficial veins, 88
surface anatomy, 103
surgical anatomy, 123
Hepatic ducts, 469, 484
flexure, 425, 427
plexus, 470, 471
Hernia, 396
femoral, 206, 401
inguinal, 396
congenital, 400
direct, 398, 399
infantile, 400
oblique, 398
obturator, 533
sciatic, 533
umbilical, 402
Hesselbach's triangle, 383, 397, 399
Hilum of kidney, 488
of ovary, 594
of spleen, 416
of suprarenal body, 495
Houston, valves of, 564
Hunter's canal, 213
Hydatids of Morgagni, 393
Hymen, 348
Hypochondriac region, 408
Hypogastric plexus, 470, 521, 586
region, 408
zone, 407
Hypothenar eminence. 103
Ileo-caecal fossa, 444
orifice, 426, 457
valve, 457
Ileo-colic fossa, 444
Ileum, 424, 455
Iliac colon, 425, 429
furrow, 158
region, 408
Ilio-tibial band, 199, 219, 235, 294
Impressio cardiaca, 411
colica, 482, 489
duodenalis, 482, 489
gastrica, 479
hepatica, 489
cesophagea, 482
renalis, 482
suprarenalis, 483
Incisura augularis, 420
Incisura umbilicalis, 413
Infantile hernia, 400
Infraclavicular fossa, 14
Infrapatellar pad, 296
Infrasternal fossa, 15
Infundibula of kidney, 493
Inguinal canal, 382, 396
INDEX
611
Inguinal canal, fossce, 397
hernia, 396, 398
Inscriptiones tendineae, 37S
Intercolumnar fibres. 368
Intermuscular septa of arm, 64
of leg, 246, 262, 268
of sole, 274
of thigh, 200, 220
spaces of back, 9
of shoulder, 45
Interosseous membrane of forearm.
146, 14S
of leg, 24S, 30S
Intersigmoid fossa, 444
Inter tubercular plane, 407
Intestine, large. 40S, 425. 455
small, 40S, 424, 451
Ischio-rectal fossa. 327
Isthmus of Fallopian tube, 596
uteri, 590
Jejunum, 424. 455
Joint or Joints, acromioclavicular. 49
ankle, 304
astragaloid, 312, 319. 320
calcaneocuboid, 314, 319, 320
carpal, 149, 151. 153
carpo-metacarpal, 152, 153
coccygeal, 578
cubo-cuneiform, 317
elbow, 139
of foot, 311
hip, 235
intercuneiform, 316
intermetacarpal, 152
intermetatarsal, 319
interphalangeal, of foot, 320
of hand, 155
knee, 292
lumbo-sacral, 576
metacarpo-phalangeal, 154
metatarso-phalangeal, 320
of pelvis, 575
pisiform, 150, 153
radio-carpal, 143
radio-ulnar, 145
sacrococcygeal. : J -
sacro-iliac, 5~N
scapho-cuboid, 317
scapho-cuneiform, 316, 319
shoulder
tarso-metatarsal. 317. 319. 320
tibio-fibular, 308
transverse carpal, 15 1
tarsal, 316
wrist, 143
Kidney, 486
calices, 493
capsule, 492
columns. 494
cortex, 494
form, 4 8 "
hilum, 488
medulla, 493
papillae, 493
pelvis, 492
sinus, 4
structure, 492
surfaces, 4S9
ureter, 488, 492. 494. :_:
5&
Knee, arterial anastomosis, 290
articular nerves. 291
joint, 292
surface anatomy, 190
Kolliker, muscular tunic of. 393
Labia majora, 345
minor:.. 345, 546
Lacteal vessels. j._x
Lacunae urethrales. 573
Leg. 241
anterior compartment, 246, 247
tibio-fibular region, 2_:
cutaneous nerves. 243. 260
fascia, 245, 261, 264. 271
intermuscular septa, 246, : _
268
interosseous membrane, 24S, 30S
peroneal region, 243. 256
posterior osteo - fascial compart-
ment, 261
posterior tibio-fibular region, 2_ ; .
259
superficial veins, 243, 258, 25
surface anatomy, 241
tibial region, 243, :;v
Lieberkuhn, crypts of. 4 : 5
Ligamenta brevia. 117
longa, 11-
subflava, 57
nent or Ligame: nio-
clavicular, 49, 50
alar. : ~
of ankle-joint, 305
annular, of ank. - 157
261. 27 :
of wrist. 94. 113. 124. 135
anterior common, of spine. -_
arcuate, 497. 49S. 50S
astragalo-calcaneal. ;::
6l 2
INDEX
Ligament or Ligaments, astragalo-
scaphoid, 312, 313, 316
bicornuate, 30
of bladder, false, 521, 586
true, 531
broad, of uterus, 584
calcaneo-cuboid, 311, 315, 316
calcaneo-scaphoid, 311, 312, 313,
316
of carpal joints, 151
cervical, of hip-joint, 240
conoid, 49, 50
of Cooper, 20
coraco-acromial, 50
coraco-clavicular, 49, 50
coraco-humeral, 85
coronary, 413, 438
costo-coracoid, 30
cotyloid, 235, 238
crucial, 297, 298, 300, 303, 304
cubo-cuneiform, 317
cutaneous, of phalanges, 109
of elbow-joint, 140
falciform, of liver, 404, 412, 436,
438
of foot, 311
gastro-phrenic, 432, 437
of Gimbernat, 201, 206, 369, 402
gleno-humeral, 85
glenoid, 86
of Hey, 195
of hip-joint, 174, 235
ilio-femoral, 237, 238
ilio-lumbar, 577
intercuneiform, 316
intermetacarpal, 152
intermetatarsal, 319
interosseous, of ankle, 309
interphalangeal, 155, 320
interspinous, 576
ischio-capsular, 237
of kidney, 488
of knee-joint, 292
lieno-renal, 417, 432, 436, 437,
438
of liver, 438
lumbo-sacral, 576
metacarpophalangeal^ 154
metatarso-phalangeal, 320
mucous, of knee, 297
oblique, 146, 148
sacro-iliac, 579
orbicular, 146
ovario-pelvic, 586
of ovary, 589, 594, 597, 600
of patella, 224, 294
Ligament or Ligaments, of peri-
toneum, 432, 437
phrenico-colic, 428, 432, 437, 438
plantar, 281, 315
posterior common, of spine, 576
of Poupart, 201, 206, 208, 358,
365, 369, 402
pubic, 581
pubo-femoral, 237
pubo-prostatic, 531
radio-ulnar, 147
round, of liver, 404, 413, 438, 478
of hip-joint, 235
of uterus, 584, 589, 597, 600
sacro-coccygeal, 578
sacro-genital, 521
sacro-iliac, 579
sacro-sciatic, great, 579
small, 580
scapho-cuboid, 317
scapho-cuneiform, 316
of shoulder, 83
spino-glenoid, 55
sub-pubic, 581
supra-pubic, 581
suprascapular, 55
supraspinous, 576
suspensory, of ovary, 586
of penis, 403
tarso-metatarsal, 317
tibio-fibular, 309
transverse, of ankle, 309
of hip, 235, 239
of knee, 303
metacarpal, 137, 152
metatarsal, 288, 319
of palm, 107
perineal, 338
superficial, of toes, 274
trapezoid, 49, 50
triangular, 333, 337, 344, 354,
. 5J6, 528, 572
vaginal, 116
of wrist-joint, 143
zonular, of hip, 237
Ligamentum mucosum, 297
patellce, 294
posticum Winslowii, 295
teres, of hip, 235, 239
teres of liver, 413, 438, 478
of uterus, 584, 589, 597, 600
Limb, lower, 157
back of thigh, 185
foot, 243, 272, 311
front of thigh, 190
gluteal region, 157
INDEX
613
Limb, inner side of thigh, 224
joints, 235, 292
leg, 241
popliteal space, 174
surface anatomy, 158, 175, 190, 241
Limb, upper, 1
axilla, 13
dorsal structures, 2. See also Back
forearm, 88
hand, 88
joints, 82, 139
pectoral structures, 13. See also
Pectoral region
scapular region, 42. See also
Shoulder
surface anatomy, 1, 14, 55, 103
wrist, 103, 133
Line of Nelaton, 159
Linea alba, 357, 364, 379
semilunaris, 357
Linear transversa, 37S
Liver, 409, 477, 478
connections, 409
ducts, 469, 483
fissures, 478, 480
ligaments, 412, 413
lobes, 479, 480, 481, 482
structure, 486
surfaces, 410, 478, 479, 482
vessels, 484
Lobus caudatus of liver, 480, 481
quadratus of liver, 480, 481
spigelii of liver, 482
Lumbar glands, 501, 507
plexus, 511
region, 40S
Lumbo-sacral cord, 511, 515, 557
Lymphatic glands, of arm, 63
axillary, 20, 26
external iliac, 506
femoral, 194
infraclavicular, 22
inguinal, 194
lumbar, 501, 507
mesenteric, 448
pectoral, 27
of popliteal space, 177
sternal, 20
subscapular, 27
Mammary gland, 18
Meatus urinarius, 403, 572, 589, 600
Meckel's diverticulum, 425
Mediastinum testis, 394, 395
Medulla of kidney, 493
of suprarenal gland, 496
Membrana sacciformis, 147
Membrane, costo-coracoid, 29
interosseous, of forearm, 146, 148
of leg, 248, 30S
obturator, 516, 581
thyroid, 516, 581
Mesenteric glands, 44S
plexus, inferior, 450
superior, 448, 470
Mesentery, 431
of large intestine, 440
proper, 425, 431, 433, 437, 442
suspensory muscle of, 466
Meso-appendix, 440
Meso-colon, pelvic, 429, 432, 440,
519, 535
transverse, 427, 432, 433, 440
Mesorchium, 387
Mesosalpinx, 585
Mesovarium, 585
Mid-Poupart plane, 407
Mons Veneris, 345
Morgagni, columns of, 565
hydatids of, 393
sinus of, 565
Muscle or Muscles, abductor hal-
lucis, 275, 277
abductor indicis, 13S
minimi digiti of foot, 275, 277
of hand, 121
pollicis, 119
accessorius, 281, 282
adductor brevis, 210, 225, 230
longus, 208, 210, 225
magnus, 166, 177, 189, 225,
obliquus hallucis, 2S3, 285
pollicis, 119
transversus hallucis, 284, 285
pollicis, 119, 120
anconeus, 125, 127
of ankle-movements, 308
biceps brachii, 65, 71, 74, S6
femoris, 177, 185, 186, 294,
309
brachialis anticus, 65, 72, 75
coccygeus, 404, 517, 555, 557
compressor urethra, 340, 343,
355, 5i7
coraco-brachialis. 65, 71
corrugator cutis ani, 324
cremaster, 372. 373. 396
crureus, 222, 224
dartos, 325, 349, 386
deltoid, 45, 47
detrusor urina1, 566
614
INDEX
Muscle or Muscles, dorso-epitroch-
learis, 49
ejaculator urinae, 335, 336
of elbow movements, 142
erector clitoridis, 350, 351
penis, 336, 337
extensor brevis digitorum, 248,
254
brevis pollicis, 128, 129
carpi radialis brevis, 125, 126
longus, 65, 125
carpi ulnaris, 125, 127
communis digitorum, 125, 126,
136
indicis, 128, 130, 137
longus digitorum, 247, 249, 256
hallucis, 247, 250, 256
pollicis, 128, 130
minimi digiti, 125, 127, 137
ossis metacarpi pollicis, 125,
128
primi internodii pollicis, 125,
128, 129
secundi internodii pollicis, 128,
129
external rotators of thigh, 170
of finger movements, 155, 156
flexor brevis digitorum, 275, 276,
282
hallucis, 283, 285
minimi digiti, of foot, 284, 285
of hand, 121
pollicis, 119, 139
carpi radialis, 93, 95, 139
ulnaris, 93, 95
longus digitorum, 264, 268, 269,
271, 281, 282
hallucis, 264, 268, 269, 271,
281, 282
pollicis, 94, 102, 115, 118
profundus digitorum, 94, 101,
sublimis digitorum, 93, 94, 97,
of foot movements, 320
gastrocnemius, 177, 262
gemelli, 165, 170
gluteus maximus, 162,. 164, 328
gluteus medius, 165, 172
gluteus minimus, 174, 235
gracilis, 177, 225, 233, 258
hamstring, 185
of hand movements, 145
of hip movements, 238
iliacus, 210, 234, 508, 510
infraspinatus, 52
Muscle or Muscles, inserted into
clavicle and scapula, 43
interosseous, of foot, 288
of hand, 137, 138
primi volaris, 119
of knee movements, 300
latissimus dorsi, 8, 13, 49
levator angulae scapulae, 12, 43
ani, 328, 344, 404, 517, 523,
533, 555> 599
prostata, 556
lumbricales, of foot, 281, 283
of hand, 107, 118, 137
obliquus externus abdominis, 364,
365, 368, 396
internus abdominis, 364, 370,
373, 396
obturator externus, 166, 171, 234
internus, 165, 170, 328, 517,
525, 502
omo-hyoid, 1 1, 43
opponens minimi digiti, 121
pollicis, 119
palmaris brevis, 107
longus, 93, 95
pectineus, 210, 225, 228
pectoralis major, 21, 22, 29, 31,
49
minor, 31, 36, 43
peroneus brevis, 257
longus, 257, 289
quinti digiti, 257
tertius, 247, 250, 256
plantaris, 177, 263, 262
platysma, 16
popliteus, 267, 269
pronator quadratus, 94, 102
radii teres, 74, 94
psoas magnus, 210, 234, 508, 509
parvus, 510
pyramidalis, 364, 378
pyriformis, 165, 170, 516, 562
quadratus femoris, 166, 171
lumborum, 508, 509
quadriceps extensor femoris, 222,
224, 294
of radio-ulnar movements, 149
rectus abdominis, 364, 377, 378
femoris, 174, 222, 235
rhomboideus major, 1 1, 43
minor, II, 43
sartorius, 177, 208, 212, 258
semimembranosus, 177, 185, 188,
189, 295
semitendinosus, 177, 185, 187,
258
INDEX
6i5
Muscle or Muscles, serratus magnus,
41, 43
short, of little ringer, 120
of thumb, 119
soleus, 262, 263
sphincter ani externus, 327, 538,
564
internus, 538, 564
vaginae, 350, 351
vesicae, 566
subanconeus, 78, 81
subclavius, 36
subcrureus, 224
subscapularis, 52
supinator brevis, 75, 12S, 139
longus, 65, 74, 125
supraspinatus, 51, 52
suspensory, of duodenum and
mesentery, 466
tensor fasciee femoris, 172, 173,
220
teres major, 49
minor, 52
of thumb movements, 156
tibialis anticus, 247, 248, 256
posticus, 264, 268, 269, 271,
288, 311
transversalis abdominis, 364, 374
transversus pedis, 284
perinei, 336, 350
trapezius, 6, 10, 43
triceps brachii, 76
vastus externus, 221, 223
internus, 223
Natal cleft, 158
fold, 158
Navel, 357
Nelaton's line, 159
Nerve or Nerves, acromial, 17, 43
to anconeus, 80
anterior crural, 209, 210, 217,
509, 512, 514
cutaneous, 17, 361, 374
articular, of ankle, 255, 267
of elbow, 99, 100
of foot, 256
of hip, 219, 229, 232, 240, 515
of knee, 179, 180, 184, 219,
221, 224, 233, 258, 259,
291
of shoulder, 48, 53
of Bell, 25, 28, 39
brachial, 24, 31, 36
to bulb of penis, 337
calcanean, 260, 261, 267
Nerve or Nerves, cavernous, 561
cervical, 10, 16
circumflex, 28, 45, 48
clavicular, 17
coccygeal, 557, 560
to coccygeus, 560
communicans fibularis, 177, 180,
261
tibialis, 177, 179, 261
to coraco-brachialis, 28, 71
crural, 196, 194, 203, 206, 209,
513
to crureus, 219
cutaneous, of abdomen, 361
of arm, 58
of back, 4
of chest, 17, 26
of foot, 243, 272, 280
of forearm, 58, 61, 88
of leg, 243, 260
lumbar, 5, 160
sacral, 160, 161, 164
of thigh, 185, 196
descending cutaneous, of cervica
plexus, 16
digital, of foot, 274, 279, 281
of hand, 107, 109, 112
dorsal, of clitoris, 356
of penis, 339, 340, 343, 404
external cutaneous, of thigh 161,
185, 196, 197, 209, 509, 512,
5H
cutaneous, ofmusculo-spiral, 59,
80
respiratory, of Bell, 25, 28, 39
furcalis, 511
geniculate, of obturator, 177
genital, 373, 389, 513
genito-crural, 196, 203, 206, 209,
5°9> 513
gluteal, inferior, 164, 167, 559
superior, 167, 173, 557, 559
hoemorrhoidal, inferior, 328, 331,
343
hypogastric, 361, 370, 374, 512
iliac, 161, 362, 363, 370, 374, 512
1I10- hypogastric, 161, 373, 374,
509, 512
lho-inguinal, 196, 361, 370, 373,
374, 509, 512
infraclavicular, 38
intercostal, 16, 18, 26, 373
intercosto-humeral, 25, 26, 59
internal cutaneous, of arm, 28, 59,
61, 68, 70, 74, 80
of thigh, 177, 185, 197,218,260
6i6
INDEX
Nerve or Nerves, interosseous,
anterior, 101, 103
posterior, 92, 128, 132, 137
last dorsal, 161, 374, 515
lateral cutaneous, 16, 18, 25, 26,
361, 374
to levator ani, 560
lumbar, 5, 511
median, 28, 68, 70, 74, 89, 100,
109, no, in, 119
middle cutaneous, of thigh, 196,
197, 212, 218
musculocutaneous, of arm, 28, 59,
7h 74
of leg, 244, 258
musculo- spiral, 28, 66, 68, 74,
75,78
obturator, 177, 184, 185, 218,
225, 231, 512, 514
accessory, 228, 511, 514
to obturator internus, 169
perforating cutaneous, 161, 164,
328, 559, 560
perineal, 337, 343, 356
of fourth sacral, 328, 331
superficial, 326, 328, 331, 332,
337, 343, 305, 356
phrenic, 500
plantar, external, 276, 279, 287
internal, 275, 278
pneumogastric, 469, 500
popliteal, external, 177, 180, 244,
257, 559
internal, 176, 179, 183, 559
to popliteus, 180
pudendal, long, 168, 169, 198,
333, 35°
pudic, internal, 167, 169, 329, 343,
356, 558
to pyriformis, 560
to quadratus femoris, 167, 169,
171, 560
radial, 88, 89, 93
to rectus femoris, 219
to rhomboids, II, 12
sacral, 557, 560
saphenous, external, 244, 260,
261
internal, 177, 196, 197, 212,
214, 217, 218, 244, 258, 260
to sartorius, 218
sciatic, great, 167, 169, 188, 558
small, 161, 167, 168, 176, 179,
185, 198, 261, 320, 559
to sphincter ani externus, 560
spinal accessory, 10
Nerve or Nerves, splanchnic, great,
470, 500
small, 470, 500
smallest, 471, 500
sternal, 17
subscapular, long, 13, 25, 28, 39
lower, 25, 28, 39
short, 25, 39
suprascapular, n, 53
to teres minor, 46, 48
thoracic anterior, 25, 29, 30, 31,
36, 39
posterior, 25, 28, 31, 39
tibial, anterior, 243, 245, 248,
251, 254, 256, 258
posterior, 267, 271
ulnar, 28, 68, 70, 81, 88, 89, 99,
109, 112, 119, 121
collateral, 80, 81
vagus, 469, 500
to vasti, 219
of Wrisberg, 28, 59, 70
Nipple, 16, 19
Nuck, canal of, 597
Nymphas, 346
Obturator hernia, 533
membrane, 581
Oesophageal opening of diaphragm,
499, 5oo
OZsophagus, 423
Omentum, 431
gastro-colic, 431
gastro - hepatic, 420, 431, 432,
436, 439
gastro - splenic, 417, 431, 436,
440
great, 409, 420, 431, 432, 439
small, 431, 432, 439
Opening in adductor magnus, 214
Orifice, cardiac, 418, 422
ileo-caecal, 426, 457
pyloric, 418
ureteral, of bladder, 567, 568
urethral, of bladder, 541, 545, 567
Organ of Rosenmiiller, 595
Ostium abdominale of Fallopian
tube, 596, 602
Os uteri externum, 349, 590
internum, 601
Ovarian fimbria, 596
plexus, 451, 599
Ovarico-pelvic fold, 594
Ovary, 584, 594
Oviducts, 596
Ovula Nabothi, 601
INDEX
617
Pacinian bodies, 112
Palm, 103
cutaneous nerves, 88, 99, 100, 107
fascia, 107, 108, 123
flexor tendons and sheaths, 114
short muscles, 119, 120
surface anatomy, 103
surgical anatomy, 123
Palmar arch, deep, 122, 123
superficial, 109, 123
Pampiniform plexus, 390, 599
Pancreas, 466, 468
Pancreatic duct, 468, 477
Pancreatico-duodenal plexus, 471
Papilla, bile, 477
Papillae of kidney, 493
Paraduodenal fossa, 444
Parametrium, 591
Pararectal fossa, 519, 521, 586
Paravesical fossa, 521, 586
Paroophoron, 596
Parovarium, 586, 595
Patellar plexus, 198
Pectiniform septum, 353
Pectoral region, 13
axilla, 23. See also Axilla
cutaneous nerves and arteries,
16, 26
fascia, 16, 20, 25
mammary gland, 18
muscles, 22, 31, 36, 41
surface anatomy, 14
Pelvic colon, 425, 429, 51S, 535, 582
fascia, 522, 586
parietal, 522, 523, 526, 572, 586
rectal layer, 531
recto-vaginal layer, 587
recto-vesical layer, 530
relation of vessels and nerves,
533
vesical layer, 530
visceral, 522, 528, 533, 586
white line, 528, 533
Pelvis, 516
articulations, 575, 602
blood vessels, 550, 597
diaphragm, 404, 555, 599
fascia, 522, 586
female, 582
of kidney, 492
male, 517
peritoneum, 518, 543, 583, 586
spinal nerves, 557, 599
sympathetic nerves, 561, 599
viscera, 518, 535, 563, 582, 5N7,
600
Penis, 333, 402, 574
Perineal body, 352, 587
triangle, 337, 352
Perineum, 322
boundaries, 322
central point, 336, 350
fascia, 324, 337, 349, 354
female, 345
ischio-rectal fossa, 327
male, 322
rectal triangle, 323, 326, 345, 350
superficial muscles, 336, 350
surface anatomy, 322, 345
urogenital triangle, 323, 331, 345,
35o
Peritoneum, 430
fossae, 397, 444, 519, 586
large sac, 434
ligaments, 432, 437
mesenteries, 431
omenta, 431
parietal, 430
pelvic, 518, 543, 583, 586
small sac, 434, 435
visceral, 430
Peroneal septa, 246, 262
Peyer's patches, 453, 455
Phrenico-colic ligament, 428
Pillars of external abdominal ring,
367
Plane, intertubercular, 407
mid-Poupart, 407
subcostal, 407
Plantar arch, 285, 286
Plexus or Plexuses, aortic, 450, 470
brachial, 36
cceliac, 459, 470, 471
coronary, 470, 471
cystic, 471
diaphragmatic, 470, 471
epigastric, 470
gastro-epiploic, 471
hemorrhoidal, 561
venous, 554
hepatic, 470, 471
hypogastric, 470, 521, 586
inferior mesenteric, 450, 451
lumbar, 511
ovarian, 451, 599
pampiniform, 390, 599
pancreatico-duodenal, 471
patellar, 198
pelvic, 561
prevertebral, 470
prostatic, 561
venous, 546, 554
6i8
INDEX
Plexus or Plexuses, pyloric, 471
renal, 470, 471
sacral, 557
sacro-coccygeal, 557, 560
sartorial, 212, 218, 225, 232
solar, 469, 470
spermatic, 451
venous, 390
splenic, 470, 471
subtrapezial, 10
superior mesenteric, 448, 470
suprarenal, 470, 471
uterine, 599
venous, 59S
vaginal, 599
venous, 598
vesical, 561
venous, 535, 554
Plica vesicalis transversa, 521
Pons hepatis, 478
Popliteal space, 174
boundaries, 177
contents, 176
fascia, 176
floor, 178
in section, 178
surface anatomy, 175
Portal canal, 485
Pouch of Douglas, 586
recto-genital, 519, 545
recto-vaginal, 586, 593
recto-vesical, 519, 545
utero-vesical, 586
Prreputium clitoridis, 347
Prepuce, 403
Prevertebral plexuses, 470
Processus vaginalis, 388, 400
Prostate, 518, 538, 546, 570,
574
Prostatic ducts, 571
plexus, 561
venous, 546, 554
sinus, 571
Pudendal band of sacral plexus,
558
cleft, 346
Pyloric canal, 421, 474
orifice, 418, 474
plexus, 471
sphincter, 474, 475
valve, 475
vestibule, 421
Pylorus, 418, 420, 473
Quadrate lobe of liver, 480, 481
Quadrilateral space of shoulder, 45
Rami communicantes, 511
grey, 511, 557
white, 511, 557, 560
Receptaculum chyli, 500, 507
Rectal channel, 532
Rectal triangle, 323, 326, 345, 350
Recto-genital pouch, 519, 545
Recto-vaginal pouch, 586, 593
Recto-vesical pouch, 519, 545
Rectum, 425, 517, 535, 587
columns, 565
flexures, 536, 564
interior, 563
lymphatics, 555
structure, 563, 599
valves, 537, 564
Region, epigastric, 408
hypochondriac, 408
hypogastric, 408
iliac, 408
lumbar, 408
umbilical, 408
Renal plexus, 470, 471
Rete testis, 394, 395
Retinacula of hip-joint, 240
of ileo-caecal valve, 457
Retro-colic fossse, 444
Retro-pubic pad, 542
Ring, abdominal, external, 366, 396
internal, 381, 396, 398
Ring, crural, 206, 207, 401
Rosenmuller, organ of, 595
Sac, vulvo-scrotal, 350
Sacral plexus, 557
Sacro-coccygeal plexus, 557, 560
Sacro-genital fold, 519, 521
Sacro-sciatic foramen, great, 580
small, 580
Saphenous opening, 195, 199
Sartorial plexus, 212, 218, 225, 232
Scapula, arterial anastomosis around,
54
Scapular region. See Shoulder
Scarpa's triangle, 208
Sciatic band of sacral plexus, 558
hernia, 533
Scrotum, 386
Semilunar cartilages, 298, 302
fold of Douglas, 379
ganglion, 470
Seminiferous tubules, 394
Septa, intermuscular, of arm, 64
of leg, 246, 262, 268
of sole, 274
of thigh, 200, 220
INDEX
619
Septa, peroneal, 246, 262
Septum crurale, 206, 401
pectiniforme, 353, 574
Sheath, axillary. 31, 32
femoral, 203, 21 1, 401, 509
of flexor tendons, of foot, 2S1
of hand, 114, 116, 123
of prostate, 531, 546
of rectus abdominis, 377, 37S
Shoulder, 42
cutaneous nerves, 43
fascia, 43
intermuscular spaces, 45
joints and ligaments, 49, 55, 82
muscles, 45, 49, 52
parts beneath deltoid, 47
surface anatomy, 2, 14
Sinus of kidney, 488
lactiferi, 20
of Morgagni, 565
pocularis, 571
of portal vein, 485
prostatic, 571
Solar plexus, 470
Sole of foot, 272
cutaneous nerves, 272, 279
fascia, 272
first layer of muscles, 275
fourth layer of muscles, 275, 288
Sole of foot, intermuscular septa, 274
second layer of muscles, 275, 281
third layer of muscles, 275, 283
Solitary glands, 453, 454, 455
Spermatic cord, 358, 369, 372, 381,
382, 387, 389, 396
plexus, 451
venous, 390
Spigelian lobe of liver, 482
Spleen, 414, 417, 423, 472
Splenic flexure, 425, 427
plexus, 470, 471
Stomach, 408, 417
blood vessels, 462
cardiac part, 420
position, 421
pyloric part, 420
structure, 472
Stomach-bed, 419
Subacromial bursa, 47
Subcostal plane, 407
Subscapular bursa, 53, 55, S4, S7
Sulcus, gluteal, 158
Sulcus intermedins, 421
Suprarenal body, 486, 490, 494
plexus, 470, 471
Sustentaculum lienis, 428
Sympathetic, ganglia, 470, 510, 561
gangliated cord, 500, 509, 510,
561
plexuses, 470, 561
rami communicantes, 511, 557,
560
Symphysis pubis, 5S1
Taeniae coli, 40S, 426, 456
Tendo Achillis, 264
Tendon, conjoined, 370, 372, 376,
396, 399
Testicle, 390
body, 392
descent, 387
epididymis, 392, 395
structure, 394
Thenar eminence, 103
Thigh, 185
adductor muscles, 225
anterior aspect, 190
cutaneous nerves, 185. 196
external rotator muscles, 170
fascia, 185, 191, 194, 198, 219
hamstring muscles, 1S5
inner aspect, 224
intermuscular septa, 200, 220
osteo-fascial compartments, 201
posterior aspect, 1S5
Scarpa's triangle, 20S
superficial veins, 176, 196
surface anatomy, 190
Thoracic duct, 499, 507
Thyroid membrane, 516, 5S1
Torus uterini, 586
Triangle of base of bladder, 549
of Hesselbach, 383, 397, 399
perineal, 337, 352
rectal, 323, 326, 345, 350
of Scarpa, 20S
urogenital. 323. 331. 345. 350
Triangular ribro-cartilage of wrist,
143, 146
space at elbow, 74
space of shoulder. 45
Trigone of bladder, 56S
Trigonum Petiti, 10, 36S
Tube, Fallopian, 584, 594. 596.
602
Tuber omentale. 467, 479
Tubules, seminiferous, 394
Tubuli recti testis, 395
Tunic, abdominal, 360
Tunica albuginea, 394
vaginalis. 3S7. 391, 393
vasculosa testis, 394
620
INDEX
Umbilical fissure, 478
hernia, 402
region, 408
zone, 407
Umbilicus, 357, 396
Urachus, 397, 540
Ureter, 448, 492, 494, 545. 588, 593
Ureteral orifices of bladder, 567, 568
Urethra, 569
aperture in triangular ligament,
339
direction of canal, 574
external orifice, 345, 348
female, 355, 583, 588, 600
membranous, 340, 569, 572
mucous membrane, 573
prostatic, 340, 569
spongy portion, 340, 569, 572
Urethral orifice of bladder, 541, 545,
567
Urogenital fissure, 346
triangle, 323, 331, 345, 35°
Uterine plexus, 599
venous, 598
Utero-sacral fold, 586
Utero- vesical pouch, 586
Uterus, 582, 583, 589
broad ligaments, 584
cervix, 590, 601
external os, 349, 601
interior, 600
position, 591
round ligament, 584, 589, 597, 600
wall, 600
Utriculus, 571
Uvula vesicae, 567
Vagina, 582, 583, 592, 602
Vaginal orifice, 345, 348
plexus, 599
Valve, ileo-caecal, 457
pyloric, 475
Valves, anal, 565
of Houston, 564
rectal, 537, 564
Valvule conniventes, 452, 455, 477
Vas deferens, 390, 393, 398, 518,
548
\ asa efferentia, 392, 395
Vein or Veins, axillary, 28, 30, 35
azygos major, 499, 507
minor, 500, 507
basilic, 62
capsular, 502
cephalic, 22, 30, 63
circumflex iliac, deep, 506
Vein or Veins, coronary, 459
cystic, 461
dorsal, of clitoris, 356, 598
of penis, 340, 404, 554
epigastric, deep, 506
femoral, 206, 212, 216
hemorrhoidal, 554, 555
hepatic, 484, 485, 504
iliac, common, 504, 505
external, 402, 506
internal, 555
ilio-lumbar, 505, 554
lumbar, 504, 515
ascending, 516
median, 62
median-basilic, 62, 74
median-cephalic, 62, 63, 74
mesenteric, inferior, 448, 450
superior, 447
ovarian, 504, 599
of pelvis, 554
phrenic, 502, 504
popliteal, 176, 182, 184
portal, 462, 484, 486
profunda, 62
radial, 62, 88
renal, 488, 503, 504
sacral, middle, 505, 554
saphenous, external, 176, 243, 260
internal, 177, 192, 196, 243,
258, 259
spermatic, 389, 390, 504
splenic, 462
superficial, of arm, 62
of elbow, 62
of foot, 243
of forearm, 62, 88
of leg, 243, 258, 259
of lower limb, 176, 243
suprarenal, 504
thoracic axis, 30
ulnar, 62, 88
umbilical, 404, 413, 438, 478, 485
uterine, 598
vein, vaginal, 598
Vena cava inferior, 477, 500. 504
fossa for, 483
Vena-caval opening of diaphragm,
499, 500
\ ermiform appendix, 426, 458
Verumontanum, 570
Vesical plexus, 561
venous, 535, 554
Vesicule seminales, 518, 548, 575
Vestibule, bulb of, 352
of vulva, 34S
INDEX
62 1
Villi intestinales, 453, 455
Vincula accessoria, 117
Vulva, 345
Yulvo-scrotal sac, 350
White line of pelvis, 528, 533
Whitlow, 123
Winslow, foramen of, 434,
481
Wirsung, canal of, 468
436>
Wrist, 103, 133
annular ligaments, 90, 94, 113,
124, 135
anterior aspect, 103
dorsum, 133
joint, 143
Zone, costal, 407
hypogastric, 407
umbilical, 407
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